bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Tillage Depth Based on Physical Properties of Soil for Rice Production in Korea
Authors: Kim Lee Yul , Cho Hyun Jun , Chung Sun Ok , Park Won Yeop , Lee Kyou Seung
Published: March 2009

Compaction is becoming a great concern in crop production and the environment. Recently,
three has been a need of field management based on site-specific conditions to improve sustainability
of agriculture and reduce environmental damage. In the study, soil management or tillage depth was
recommended nondestructively based on cone index profiles for typical Korean rice paddy fields.
Field variables related to tillage, soil strength, rice growth, and other soil physical properties showed
considerable spatial and vertical variations as well as significant (α<0.1) correlations among them.
Cone index profiles observed also varied by field sites, and maximum cone index and depth to the
maximum cone index showed significant (α<0.1) correlation with tilled depth as well as rice growth
and other field variables. When soil management was recommended based on CI measurements, 13.4,
16.8, and 95.3% of the total surveyed areas, and 10.6, 18.9, and 51.6% of the total soil volume were
chosen for management depth of 10, 20, 40 cm, respectively, indicating that soils of many field sites
would not restrict rice growth. It was concluded that the concept of site-specific soil management
based on soil conditions could save labor, time, machine use, and energy.
Fast and Accurate Color Space Conversion Matrix
Authors: Seo Jong Wan , Shin Myung Chul
Published: March 2009

A color space used to create color on a computer monitor or a television screen is RGB
color space. However, RGB color space is strongly related to each other, therefore RGB color space is
inadequate for adjustment of brightness or contrast. Moreover RGB color space is not suitable for
pattern recognition. For this reason, it is needed that color space conversion from RGB to YIQ, YUV
or YCrCb. The color space conversion matrix consists of 3 by 3 matrix element that is represented by
floating point numbers. However RGB or YUV color space is in integer domain. Therefore these
transform lead to lose the least significant bit (LSB) of color space. We propose the simple and fast
reversible transform matrix. No lose the least significant bit (LSB) and not required multiplication but
shift and addition that provides for real time conversion of huge image.
Evaluation of Recovery Process of Pure Magnesium at Room Temperature By Acoustic Emission
Authors: Li Yun Ping , Enoki Manabu
Published: March 2009

Present study was conducted in order to expand the applications of acoustic emission
(AE) as a tool in evaluation of the recovery behavior of pure magnesium after deformation at room
temperature. From our previous research, we confirmed that AE from magnesium and its alloys
during recovery process at room temperature is a unique characteristic and AE measurement should
also be a promising approach in investigating such characteristic phenomenon. In present research,
magnesium with purity of 99.95% was selected as the main research objective, and the cylinder
specimen was compressed with strain rate of 1.67×10-4/s and unloaded with extremely high strain
rate of 0.56/s for the forthcoming AE evaluation in anelastic recovery process. The AE behavior
during anelastic recovery process and parameters such as anelastic recovery strain and twin
densities etc. were analyzed in detail. Pseudoelastic behavior of pure magnesium was considered to
be related to the detwinning and dislocation motions by the driving force of internal stress.
Evaluation of Grouting Performance Using Electrical Resistivity Tomography
Authors: Thanh Nguyen Duc , Cho Gye Chun , Sim Young Jong , Lee Seok Won
Published: March 2009

This study proposes a tomography-based method for evaluating grouting performance after
injection. Tomography is a convenient approach for solving the boundary measurement inverse
problem of capturing discrete pixels and synthesizing these pixels into a unified image. Four arrays of
eight electrodes are installed into large triaxial cell specimens to simulate in-situ crosshole resistivity
testing. Sand is used as a base material and a wet cement mixture is grouted into the specimens.
Electromagnetic waves are used as a means of accumulating the physical properties of the specimens.
Each measured electrical resistivity is considered as a discrete signal. The electrical resistivity
distribution is calculated and optimized through an iterative modified least-squares inversion based
on a forward solution of Coulomb and Gauss’s law equations. Results show that the electrical
properties of an injected grout material and its location and size can be effectively estimated from a
series of resistance measurements.
Rock Mass Classification Using Electrical Resistivity - an Analytical Study
Authors: Choi Jun Su , Ryu Hee Hwan , Lee In Mo , Cho Gye Chun
Published: March 2009

Geophysical prospecting using electrical resistivity is one of the principal methods for
subsurface exploration. However, the majority of such application methods are restricted to coarse
descriptions of underground conditions. The Q-system is commonly used as a representative rock
mass classification system in modern rock engineering. In this paper, electrical resistivity is related to
the Q-system through theoretical analyses. The analyses are based on Coulomb's law and Gauss' law
considering electrical characteristics of constituent parameters for rock mass classification such as
joint thickness, joint condition, joint spacing, intact rock strength, and RQD. The results show that
there is a strong correlation between electrical resistivity and rock mass classification.
Characterization of Clay Sedimentation Using Piezoelectric Bender Elements
Authors: Chang Il Han , Cho Gye Chun , Lee Joo Gong , Kim Lee Hyung
Published: March 2009

Sedimentation is one of the most basic processes in the formation of a soil structure in
nature. Many studies have been performed to describe the characteristics of clay sedimentation, based
on settlement and water content measurement. In addition, there have been some attempts in
numerical modeling to describe soil structure formation as a whole. However, these effects still fall
short in explaining the overall process of soil structure formation because some relevant properties are
measured after a self-weight consolidation is completed. Furthermore some measurement techniques
significantly alter soil structure. Thus, a non-destructive evaluation is necessary for the effective
description of soil characteristics during the sedimentation process. In this study, a testing device is
designed that continuously monitors the self-weight consolidation process of sedimentation with
shear waves. Piezoelectric bender elements are installed into a testing cell to generate and receive
shear waves in a small strain regime. Slurries are prepared with kaolinite-type clay and placed in the
cell. Shear wave velocities are continuously measured as a function of time during the whole process
of the self weight consolidation. The experimental results suggest that as clay sediment is subjected to
a certain loading, the shear wave velocity increases as time increases, showing an abrupt change in log
time. This abrupt change is relevant to the formation of a stable soil skeleton. It is concluded that the
time-dependent variations in shear wave velocity reflect sedimentation and self weight consolidation
behavior and the evolution of the effective stress increment.
Spectrum Analysis of an Ultrasonic Signal According to a Surface Status by Using a Robust Laser-Based Ultrasonic System
Authors: Park Seung Kyu , Baik Sung Hoon , Lim Chang Hwan , Kim Cheol Jung , Kang Young June
Published: March 2009

A laser-based ultrasonic inspection system is a non-contact scanning device with a high
spatial resolution and a wide spectrum bandwidth. In this paper, we developed a laser-based
ultrasonic inspection system by fabricating a pulse laser and a Confocal Fabry-Perot Interferometer
(CFPI) with a dynamic stabilizer. The dynamic stabilizer generates ultrasound by adaptively
obtaining the time of the maximum gain of the CFPI whose gain is varied with the time. Then, a
computer adaptively corrects the measurement error by using the gain of the CFPI at the measuring
time. In this paper, we describe the hardware configurations and the control algorithms to build the
stable laser-based ultrasonic inspection system. We have investigated an ultrasonic signal in the time
and frequency domain to detect micro cracks through experiments. We experimentally confirmed that
the proposed error correction method is effective for improving the performance of the system and the
configured ultrasonic inspection system is stable
Evaluation of Effect of Process Conditions on Microstructures in Plasma Sprayed Coating by In Situ Laser AE
Authors: Taniguchi Koichi , Nishinoiri Satoshi , Enoki Manabu , Tomita Koichi
Published: March 2009

In recent years, a thermal barrier coating technology becomes more important because it is
required to develop materials which avoid high-temperature oxidation and corrosion. In order to
ensure reliability of coating, it is necessary to understand microfracture criterion in terms of stress
distribution and fracture morphology. The objective of this study is to clarify the damage generation
process by comparing Acoustic Emission AE) generation behavior and thermal stress simulation
result based on heat history measurement. Al2O3 as the top coat (TC) and NiCrAlY as the bond coat
(BC) were sprayed to SUS304 disc or plate as a base material. AE in cooling process were detected by
laser heterodyne interferometer after spraying finished. Two-dimensional axisymmetric mesh for
samples was made and transient heat conductivity was analyzed for various boundary conditions.
Then, using the obtained heat history, transient heat stress was analyzed and the distribution of stress
elements was calculated. The fracture process of ceramic coating was evaluated from these
experiments and analyses.
Detection and Image Processing of Interfacial Micro-Delamination in the Thin-Layered Structure by Using Nonlinear Ultrasonic Effect
Authors: Ha Job , Jhang Kyung Young
Published: March 2009

The detection of interfacial micro-delamination in the thin-layered structure such as the
electronic package becomes very important as the electronic device becomes smaller and thinner. The
conventional method used to detect the delamination in an electronic package is to use a scanning
acoustic microscope (SAM). However, despite its high performance qualities, SAM is often faced
with a tricky decision when a delaminated gap is too small. In this paper, a novel method based on
ultrasonic nonlinearity is proposed to overcome this limit. The proposed method is integrated into the
conventional SAM equipment, and its effectiveness is verified by experiments for the Newton Ring
and the real semiconductor package that have micro-delaminations. The results showed that the
nonlinear parameter had good correlation with the gap size of delamination. A method of imaging the
nonlinear parameter is also proposed to assure the feasibility of the proposed method in the field
application.
The Tribological Behaviors of the Surfaces Lubricated by Polyaklylene Glycol and Polyolester Oils in Carbon Dioxide Environment
Authors: Oh Se Doo , Ahn Tae Shik , Cho Sung Oug , Lee Young Ze
Published: March 2009

The carbon dioxide (CO2) is investigated as an alternative refrigerant to replace HFC
(hydro fluorocarbon) refrigerants in refrigerators and air conditioning systems due to the
environmental concerns. Because new compressors with the carbon dioxide are going to be
operated under the high pressure, the tribology of sliding surfaces in the compressor becomes very
important. To develop new compressors, especially rotary type, the friction and wear characteristics
of sliding surfaces between a vane and a roller in the rotary compressor were evaluated in this
paper. Several hard coatings, such as TiN, CrN, and WC/C, were applied on vane surfaces in order
to improve the tribological characteristics, and their performances were evaluated experimentally.
The vane-on-disk type sliding tests were carried out under the various sliding speeds, normal loads,
and carbon dioxide pressures with an exclusive high pressure wear tester. From the tests wear
volume of vane surfaces applied various coatings were compared. During the tests coefficients of
friction and surface temperatures were monitored. Test results showed that WC/C coatings showed
good tribological properties. TiN and CrN coated vanes showed good wear resistance properties but
produced high friction.
Measurement of Low-Frequency Wave Propagation in a Railway Contact Wire with Dispersive Characteristics Using Wavelet Transform
Authors: Park Sung Yong , Jeon Byung Uk , Lee Jang Moo , Cho Yong Hyeon
Published: March 2009

The railway contact wire, which supplies electric railways with electric power, plays an important role in determining the maximum railway velocity. In general, the maximum allowable velocity of an electric railway is less than seventy percent of the wave propagation velocity of the contact wire. Because the contact wire is more a beam model with dispersive wave characteristics than a string model, the wave propagation velocity depends on the frequency. For this reason, there have been only few studies on the wave propagation of the contact wire. In this paper, we proposed two useful methods for estimating the wave propagation velocity of the railway contact wire by using the Gabor wavelet transform on the experimental signals. In the first method, the ridges of wavelet transform, which contain the essential information about dispersive characteristics, are used. Specifically, the wave propagation velocity of the contact wire can be extracted from the time difference of the wavelet ridges of the measured signals. In the second method, the cross-correlation analysis of each wavelet transform is used to extract the wave propagation. The selection of the optimal Gabor shaping factor for the best time-frequency localization by using the Shannon entropy cost function is also discussed.
Experimental Study of Evaluating Bio-Mechanical Characteristics of Cushioning System Using Nano-Shock Absorption Pocket
Authors: Moon Byung Young , Lee Chun Tae , Son Kwon , Chung S.W.
Published: March 2009

This study developed and evaluated a shoe cushioning system to reduce impact force
patterns during running. The shoe cushioning system is composed with a polyurethane pocket, which
contains water and porous grains to absorb the force against the weight inside the pocket.
Load-displacement curves for the shoe cushioning system were obtained from an instrumented testing
machine and the results were compared with various pockets that have air, water or grains.
Mechanical testing showed that the pocket with 5 g particles was the best for the shoe cushioning
system. This founding will be helpful to designing the shoe.
The Study on Mechanical Properties in Narrow-Gap Welds for SA312 TP347
Authors: Woo Seung Wan , Lee Choon Yeol , Kwon Jae Do , Choi Young Hwan , Shin Ho Sang
Published: March 2009

Conventionally, shielded-metal arc welding (SMAW) process has been applied to join
pipes of reactor coolant loop, which caused defects and lot of loss in time and cost due to excessive
heat input in joining section. Recently, narrow-gap welding (NGW) process was introduced to
overcome the disadvantages of SMAW. However, the application of NGW to nuclear power plant is
not yet commonly used, because safety of NGW process is not fully proven. In the present paper,
welded coupons are made of stainless steel. They are manufactured under different processes; general
welding (GW), and repair welding after GW. Performed are various mechanical tests to investigate
microstructure, tensile strength and so on. It is verified that the mechanical properties of stainless steel
are slightly changed after repair welding process. It is also found from stress corrosion cracking tests
that the failure time of repair welding is shorter than that of general welding.
The Weldability of Primer-Coated Steel for Shipbuilding by CO2 Laser
Authors: Kim Jong Do , Oh Jin Seok , Park Hyun Joon
Published: March 2009

The application of laser welding technology has been considered to shipbuilding structure. However, when this technology is applied to primer-coated steel, good quality weld beads are not easily obtained. Because the primer-coated layer caused the spatter, humping bead and porosity which are main part of the welding defect attributed to the powerful vaporizing pressure of zinc. So we performed experiment with objectives of understanding spatter and porosity formation mechanism and producing sound weld beads in 6 t primer coated steels by a CO2 CW laser. The effects of welding parameters; defocused distance, welding speed, coated thickness and coated position; were investigated in the bead shape and penetration depth on bead and lap welding. Alternative idea was suggested to suspend the welding defect by giving a reasonable gap clearance for primer coated thickness. The zinc of primer has a boiling point that is lower than melting point of steel. Zinc vapor builds up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Significant effects of primer coated position were lap side rather than surface. Therefore introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, formation and suspension mechanism of the welding defects was suggested by controlling the factors.
Comparison between Conventional and Performance Demonstration UT Method by Round Robin Test
Authors: Kim Yong Sik , Yang Seung Han , Yoon Byung Sik , Lee Hee Jong
Published: March 2009

The results of ultrasonic testing performed during in-service inspection period for main
components of nuclear power plant are affected by the performance of each inspector. To enhance
the inspection reliability, the more restrictive qualification is required. KEPRI established Korean
performance demonstration (KPD) system for the ultrasonic testing personnel, equipment and
procedure which applied to the piping examination of nuclear power plant. A round robin test was
conducted to evaluate the reliability of examination result by comparing conventional (DAC) UT
and performance demonstration (PD) UT method. Participants took detection/length sizing test and
depth sizing test using DAC method and PD method. The results showed that the PD method was
preciser and more accurate than the conventional DAC method in length and depth sizing regardless
of field experience and PD qualification status.
Making Sense of Non-Destructive Evaluation Data with an Artificial Intelligence Approach
Authors: Nguyen Minh , Wang Xiao Ming , Foliente Greg
Published: March 2009

This paper presents the feasibility of an artificial intelligence technique for processing
and interpretation of non-destructive evaluation (NDE) data from assessments of engineering
structures. The technique used is a learning and reasoning approach with belief network. With this
technique, causal factors and consequent indicators in the data structure in relation with
structure/material condition can be modelled, and their causal relationship can be established using
the NDE data as the learning resource. Fundamentals of the technique are briefly presented, and
then the potential applications of the technique to NDE data are demonstrated in two case studies.
Non-Contact SWP Stability Estimation Using Laser-Ultrasonic Wave
Authors: Song Kyung Seok , Kim Jae Yeol , Kim You Hong
Published: March 2009

Contact type detection, one of UT for the detection of defects in welding area, has several weak-points. Proximity type ultrasonic inspection using laser is being studied these days to make up for the weak points of contact type ultrasonic inspection. In this paper, automatic inspection system of the welding area of spiral welding pipe has been developed, of which mechanical characteristic is better than that of circular directional pipes, and executed the proximity ultrasonic inspections using laser. The usefulness of proximity ultrasonic inspection using laser will be verified in this paper through the analysis of the inspection results.
Comparison of Absolute and Differential ECT Signal Characteristics Obtained at Tubesheet and Tube Expansion Area
Authors: Shin Young Kil , Song Sung Chul , Jung Hee Sung , Im Chang Jae , Song Myung Ho
Published: March 2009

Steam generator tubes are expanded inside tubesheet holes and the crevice gap between
tubesheet and the tube should be minimized. To examine tube expansion area, eddy current testing is
usually used. In this paper, absolute and differential signals are computed by a numerical method for
several different locations of transition region and signal variations due to tubesheet, tube expansion
and operating frequencies are observed. Results show that low frequency is good for identifying the
location of tubesheet, and high frequency is good for the measurement of expanded tube diameter and
the recognition of transition region. In general, absolute signal is good for measuring tube diameter
and the differential signal has advantages of locating tubesheet and both ends of the transition region.
A Study on Material Degradation in Carbon Steel for Pressure Vessel at 179°C
Authors: Baek Un Bong , Park Jong Seo , Nahm Seung Hoon , Lee Hyuck Mo
Published: March 2009

In spite of frequent defect in industrial boilers, life assessment or diagnostic method for
them has not been studied. In this research, SB410 carbon steel used in industrial boilers is simulated
with artificial aging heat treatment. To do qualitative life assessment, differences in micro-structures
and hardness of SB410 by the degradation time are studied. In addition, variation in material
properties by aging was observed with the tensile test at room temperature and 179 °C and changes in
ductile to brittle transition temperature was observed with the charpy impact test performed at several
test temperature.
Development of Biaxial Servo Controlled Fatigue Testing System
Authors: Shimamoto Akira , Hwang Do Yeon , Nemoto Tetsuya
Published: March 2009

Destructive accident sometimes takes place though the equivalent stress is rather low in the
viewpoint of strength of materials. The propagation of fatigue cracks under multi-axial stress state
and cycling load gives the reason. Fatigue fracture has been considered as one of the most commonly
encountered industrial problems that lead to the damage of components in engineering products. In
general, the machine structure is always under stress concentration or stress cycles. Moreover, the
structure material is usually under two axes or multi-axial stresses instead of uniaxial stress state. It is
important, therefore, to clarify the propagation behavior and the fatigue failure problem of the crack
under the multi-axial stresses and cycling load from the safety reliability and accident prevention
measure. In this study, a biaxial fatigue experimental device was developed which can carry out a
wide range of fatigue tests under biaxial stresses. The developed experimental device was identified
with a biaxial fatigue experiments including static uniaxial and biaxial tensile test by using the
aluminum alloy flat plate as specimens. The propagation behavior of fatigue crack for center notched
cruciform specimen in the equal biaxial fatigue test was verified.
Inverse Models and Implications for NDE
Authors: Balasubramaniam Krishnan
Published: March 2009

Any NDE process may be considered to involve three systems, each having a unique set of parameters that define its characteristics viz. (a) The Input to the material, (b) The material itself, and (c) The output response measured by the NDE system. Traditionally, the input and the material parameters are assumed known and numerous Forward Models have been developed that predict or estimate the output response function. Over the years, forward models are very well established and serve the key purpose, for improved interpretation of the, as well as to optimize the input parameters to obtain the desired, output response. The other two scenarios i.e. if the output response function in the form of measured data is available, to obtain one of system parameters, i.e. either the input function or the material properties, while the other one is assumed to be known are classified as Inverse Problems. Due to the availability of computational resources, the inverse problem solutions are becoming increasingly feasible. Typical applications include measurement of material properties such as modulus, viscosity, temperature, hardness and stress profiles, etc. This paper will discuss the different techniques and the kinds of problems that have been successfully addressed in the area of NDE and their implications on the expanding horizons in NDE.
Evaluation of High Temperature Characteristics in Gas Turbine Blades
Authors: Kim Hyung Ick , Park Hong Sun , Bae Bong Kook , Lee Young Min , Seok Chang Sung , Kim Moon Young
Published: March 2009

The Ni-based superalloy GTD-111DS has been widely used as the material of the first stage
blade of gas turbine. But there are little data available on the microstructure and mechanical property.
The strength and ductility of GTD-111DS decrease more rapidly due to the acceleration of its
microstructure degradation under high temperature. The results of study showed that the shape of γ'
did not change with increased aging time but the amount and volume fraction of the deposition of
secondary γ' increased and secondary γ' grew among primary γ'. Also there was difference of yield
strength and tensile strength in room temperature according to heat treatment and collecting region.
The Contact Fatigue Life Evaluation According to Contact Surface Removal
Authors: Seo Jung Won , Kwon Seok Jin , Hur Hyun Mu , Choi Jae Boong , Kim Young Jin
Published: March 2009

Railway wheels and axles have been one of the most critical components in a railway
vehicle. The service conditions of railway vehicles have became more severe in recent years due to the
increase of the speed. It is very important to evaluate the reliability of wheels with regard to safety,
because wheel failure can cause derailment with loss of life and property. One of the major reasons of
the railway wheel damage is the contact zone failure by wheel/rail contact. One of the methods for
preventing the failure and increasing the fatigue life is to grind periodically the contact surface before
reaching the failure. The increase or decrease of the contact fatigue life by the surface removal of the
contact surface were shown by many researchers. However, the reason why fatigue life increases or
decrease has not been investigated obviously. In this study, the effect of the surface removal depth on
the contact fatigue life for a railway wheel is evaluated through the employment of rolling contact
fatigue tests and the finite element analysis. It is found that the contact fatigue life increased with the
removal depth. But in the case that the removal depth is greater than the optimal depth, the contact
fatigue life decreased. It seems to be obvious that the residual strain is the main factor determining the
fatigue life according to the removal depth
A Study on the Improvement of Durability of Gear Steel by Shot Peening
Authors: Lee Dong Sun , Kim Tae Hyung , Lee Jae Heon , Lee Tae Kun , Cheong Seong Kyun
Published: March 2009

In this paper the fatigue life of spur gear was investigated by changing the shot peening condition. From bending fatigue test depending on various shot peening intensity, fatigue characteristics were investigated. The causes of reduction in fatigue life were analyzed by observing the surface of gear with Scanning Electron Microscope(SEM), and impact of residual stress to fatigue characteristics was identified by measuring compressive residual stress depending peening intensity by depth. The results show that the optimum shot ball velocity is 65 m/s and optimum peening time is 8 minutes. From SEM image, the micro-crack was observed at the surface in case of over peening. This seems to be the factor which reduces fatigue life by decreasing compressive residual stress of surface.
Measurement of Thermal Expansion Coefficients of Thin Film of Different Organic Coatings by Shearography
Authors: Habib Khaled
Published: March 2009

In the present work, thermal expansion coefficients of a number of organic coatings were
studied by a non-destructive technique (NDT) known as shearography. An organic coating, i.e.,
epoxy, on a metallic alloy, i.e., carbon steels, was investigated at a temperature range simulating the
severe weather temperatures in Kuwait especially between the daylight and the night time
temperatures, 20-60 0C. The investigation focused on determining the in-plane displacement of the
coating, which amounts to the thermal deformation (strain ) with respect to the applied temperature
range. Along with the experimental data, a mathematical relationship was derived describing the
thermal deformation of a coated film as a function of temperature. Furthermore, results of
shearography indicate that the technique is very useful NDT method not only for determining the
thermal expansion coefficients of different coatings, but also the technique can be used as a 2Dmicroscope
for monitoring the deformation of the coatings in real-time at a submicroscopic scale.
The Evaluation of Fretting Fatigue Life for Inconel 600 and 690 Alloy
Authors: Park Dae Kyu , Bae Yong Tak , Choi Sung Jong , Chai Young Suck , Kwon Jae Do
Published: March 2009

The initial crack under fretting condition occurs at lower stress amplitude and at lower
cycles of cyclic loading than that under plain fatigue condition. INCONEL alloy 600 and 690 are
high–chromium nickel alloy having excellent resistance to many corrosive aqueous media and
high-temperature atmospheres. In this paper, the effect of fretting damage on fatigue behavior for
INCONEL alloy 600 and 690 were studied. Also, various kinds of mechanical tests such as hardness,
tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with flat-flat
contact configuration using a bridge type contact pad and plate type specimen. Through these
experiments, it is found that the fretting fatigue strength decreased about 40~70% compared to the
plain fatigue strength in two materials. In fretting fatigue, the wear debris is observed on the contact
surface, and the oblique micro-cracks at an earlier stage are initiated. These results can be used as
basic data in a structural integrity evaluation of heat and corrosion resisting alloy considering fretting
damages.
Application of Laser-Generated Ultrasound for Evaluation of Thickness Reduction in Carbon Steel Pipes
Authors: Park Jong Ho , Lee Joon Hyun , Seo Gyeong Chul , Choi Sang Woo
Published: March 2009

In carbon steel pipes of nuclear power plants, local wall thinning may result from
erosion-corrosion or flow-accelerated corrosion(FAC) damage. Local wall thinning is one of the
major causes for the structural fracture of these pipes. Therefore, assessment of local wall thinning
due to corrosion is an important issue in nondestructive evaluation for the integrity of nuclear power
plants. In this study, laser-generated ultrasound technique was employed to evaluate local wall
thinning due to corrosion. Guided waves were generated in the thermoelastic regime using a
Q-switched pulsed Nd:YAG laser with a linear slit array. . In this paper, time-frequency analysis of
ultrasonic waveforms using wavelet transform allowed the identification of generated guided wave
modes by comparison with the theoretical dispersion curves. Modes conversion and group velocity
were employed to detect thickness reduction.
Infrared Thermographic Technique to Measure Corrosion in Reinforcing Bar
Authors: Chung Lan , Paik In Kwan , Cho S.H. , Roh Young Sook
Published: March 2009

The corrosion reinforcing steel in concrete structures is detrimental to its service life. In
order to increase lifespan and maintain serviceability, a qualitative measurement technique that can
measure the extent of corrosion of reinforcing steel needs to be developed. While considerable researches
have been carried out focusing only on detecting corrosion and restraining the progress of
corrosion, a qualitative measurement technique that can measure the amount of corrosion in rebar
need to be developed. The purpose of this research is to develop a new technique to measure the
corrosion level of rebar using accumulated thermal data. Accumulated thermal data were gathered
using infrared camera and digitized to distinguish the difference between various corrosion levels of
rebar. The test results showed that the higher level of corrosion displays the higher level of temperature.
Temperature of reinforcing steel is not severely affected by ambient temperature, however,
concrete surface temperature increased as ambient temperature increased.
High Resolution One-Dimensional Dose Measurement Using a Movable Miniature Fiber-Optic Radiation Sensor
Authors: Lee Bong Soo , Cho Dong Hyun , Chung Soon Cheol , Yi Jeong Han , Chang Kyung Won , Kim Sin , Cho Hyo Sung , Kim Si Yong
Published: March 2009

The aim of this study is to develop a new method to measure one-dimensional dose distribution of high-energy electron using a miniature fiber-optic radiation sensor. The measurements are made by a thin plastic optical fiber with an organic scintillating sensor tip. The scintillating light in the visible wavelength range is guided to a silicon photodiode by plastic optical fiber in order to convert light output to electrical signal. The one-dimensional spatial dependence of elctron beam is measured by moving the sensor tip with uniform speed. It is shown that this fiber-optic radiation sensor has better spatial resolution than conventional ion chamber and it needs much less time to measure one-dimensional dose distribution in the high radiation fields.
A Finite-Width Crack Model for Rotor Dynamic Analysis by Transfer Matrix Method
Authors: Wang Ke Ming , Xiang Song
Published: March 2009

Understanding dynamic behavior of a rotor system with a transverse crack is of great
significance for operation reliability of rotating machinery. The transfer matrix method is widely
used for rotor dynamic analysis, but it encounters difficulties modeling a crack. This study proposes
a finite-width crack model that simulates the local stiffness reduction effect of a gaping crack in
transfer matrix method. This model is obtained by comparing finite element analysis results of a
shaft with a zero-width crack and its counterpart transfer matrix calculation results with a trial
equivalent finite-width slot. Different shaft geometry and loading modes are considered to improve
the generality of the model. An application example is given that uses the proposed model to
calculate critical speeds of a multi-disk rotor system with a transverse crack at different positions.
Behavior and Fracture Mechanism of Brittle Rock with Pre-Existing Parallel Cracks
Authors: Zhang M.X. , Lee X.L. , Javadi A.A.
Published: March 2009

There is a macro-crack and micro-crack system in rock, which affects almost all the
mechanical properties of rock, especially for the fracture mechanism. The propagation of
pre-existing cracks in rock samples under load is fundamental to understanding of rock fracture
mechanisms. It is evident that assumption of Griffith theory was not in accord with the fact that
numerous cracks exist in rock. So, it is difficult to explain how the propagation of a micro-crack
developed into macro-failure by conventional theories. In order to investigate the cause and results
of fracture within the rock, the stress concentration around the micro-cracks was analyzed, which
resulted in propagation of wing cracks and connecting adjacent original cracks, eventually leading
to macro-failure. The experiments on gypseous samples with pre-existing parallel cracks (flat
rectangular in shape) under compression were carried out. The fracture mechanism and the stress
equilibrium condition at brittle rock were discussed. Based on the fracture mechanism of brittle
rock, a strength criterion of rock was proposed.
Damage Mechanics Implementation of Material Design Simulator for Layered Ceramic Composites
Authors: Lee Jae Myung , Seo Jung Kwan , Han Dae Suk , Kim Myung Hyun , Park Hong Chae
Published: March 2009

The objective of this study is to establish a numerical technique applicable for the assessment of damage characteristics of laminate ceramic. A numerical simulator, which can be used for the optimal material design, was developed based on the damage mechanics approach. To evaluate the internal damage evolution behavior within composite material, generalized damage evolution equation was developed and implemented in way of finite element method. By virtue of an automatic data interface between the commercial FEA results and damage calculation, a simple and cost-effective damage evaluation system is constructed. It was found that the developed system can be used for the evaluation of the material performance of composite.
Transformation Cyclic Damage of Near-Equiatomic Ni-Ti
Authors: Liu Yinong , Zheng Yu Feng , Mahmud Abdus , Laeng Jamaluddin
Published: March 2009

Near-equiatomic Ni-Ti alloys are known to exhibit shape memory effect associated with a
B2↔B19’ martensitic transformation. These alloys are often used in various cyclic modes in
application, typically as actuators and sensors. The B2↔B19’ martensitic transformation in Ni-Ti is
accompanied with a large lattice distortion. Cycling through this transformation, induced thermally,
mechanically or by the combination of the two, is found to cause structural damage to the alloys,
hence changes their functional properties. This study investigates the effect of transformation cycling
and heat treatment on the property stability of near-equiatomic Ti-Ni. It was found that in the case of
thermally induced transformation cycling, incomplete transformation cycles caused less structural
damage to the matrix than full transformation cycles whereas in the case of mechanically induced
transformation cycling via pseudoelasticity in tension, partial or full transformation cycling caused
similar property changes. The indifference of the case of pseudoelastic cycling is attributed to the
localisation of the deformation, commonly known as the Lüders-type deformation.
A Study on the Development of Reflective Photoelastic Experimental Hybrid Method on the Static Plane Problems of Orthotropic Material
Authors: Hawong Jai Sug , Shin Dong Chul , Han Song Ling
Published: March 2009

The reflective photoelastic experimental hybrid method for the fracture mechanics of
orthotropic material was developed in this research. it was verified that the reflective photoelastic
experimental hybrid method was more useful for the static plane problems of fracture mechanics,
for the determination of stress intensity factors and for the separation of stress components at the
vicinity of the crack-tip than the transparent photoelastic experimental hybrid method in orthotropic
materials.
Analysis of Interface Crack in Polymer Liner Subjected to Hygrothermal Stress
Authors: Lee Sang Soon
Published: March 2009

Polymeric materials such as epoxy are widely used as coating layers for the containment building of the nuclear power plant. These layers may be damaged through a hygrothermal process and residual stresses can reach significant levels near the free edges, possibly leading to interface debonding or delamination. Interfacial stress singularities induced in a laminate model consisting of the epoxy coating layer and the concrete substrate is investigated using the time-domain boundary element method. The epoxy layer is assumed to be a linear viscoelastic material and moisture effects are assumed to be analogous to thermal effects. The overall stress intensity factor for the case of a small interfacial edge crack of length a has been computed.
Microstructural Evaluation of Isothermally Aged 12Cr Steel by Magnetic Property Measurement
Authors: Kim C.S. , Kang J.H. , Byeon Jai Won , Kwun S.I.
Published: March 2009

The magnetic coercivity of ferritic 12Cr steel was experimentally studied in order to characterize its microstructures and mechanical properties during isothermal aging. As the aging time increased, the M23C6 carbide coarsened and additional precipitation of Fe2W phase was induced. The width of martensite lath increased to about 0.4μm after 4000 hrs of aging. The coercivity decreased as the number of precipitate decreased and the width of martensite lath increased. The hardness was proportional to the magnetic coercivity. These empirical linear relations suggested that the change in the microstructures and strength of ferritic 12Cr steel during thermal aging could be evaluated by monitoring the magnetic coercivity.
A Study on Load Analysis and Durability Test Condition of Automobile Brake Pedal
Authors: Noh Byeong Wook , Choi Young Woo , Bae Sung In
Published: March 2009

Automobile pedal which is loaded by driver’s input is transmitting load to throttle cable,
braking device and clutch device and controlling automobile. Measuring working condition and
applying equivalent damage are needed for reliability of developing pedal. The measuring working
condition is requiring more investigation with various respects because of widely ranged drivers, road
condition and environmental condition. Additionally, when equivalent damage is applied, there are
not suitable for test condition if equivalent damage is too high level to apply or unused region. In this
study, load history is measured with 95percentile customer. Measured load history is converted to
stress history about critical area of pedal by FEM. There are drawn up histogram of pedal cycles and
load from stress history with rain flow cycle counting method, calculated relative damage of extended
stress history with Palmgren-Miner rule. From the results, calculated total relative damage is applied
to calculation method of test time and load. Calculation method for test condition is carried out with
three methods which are enforcing with total stress by rain flow cycle counting, representative load
and blocked load. Accelerated durability test condition of pedal using with relative damage and
acceleration factors are proposed.
Seismic Capacity Requirements for Low-Rise Reinforced Concrete Buildings Comprised of Members Failing in Shear and in Flexure
Authors: Lee K.S. , Choi Chang Sik
Published: March 2009

This paper presents a method for determining required shear and flexural strengths
associated with structural damage states for various levels of earthquake demand of low-rise RC
buildings having a dual lateral-load resisting system. The interaction curves of the required
strengths are derived for various ductility ratios based on nonlinear dynamic analyses of the singledegree-
of-freedom system. Damage states of buildings controlled by both shear and flexure are
evaluated by the procedure outlined by the Japanese Standard. The proposed method predicts
reasonably well damage sustained by actual buildings during an earthquake. The proposed method
can be used to develop performance-based seismic evaluation and rehabilitation procedures of lowrise
RC buildings having a dual lateral-load resisting system.
Synthesis and Characterization of the ZnO-TiO2 Nanoparticles by a Hydrothermal Processing
Authors: Kim J.W. , Kim S.W. , Park K.S. , Lee J.K , Kim Byung Ik , Bae Dong Sik
Published: March 2009

Zinc titanate nanoparticles were prepared under high temperature and pressure conditions
by precipitation from metal precursors with aqueous ammonium hydroxide. Zinc titanates powders
were obtained in the temperature range of 180-230 for 4 h. The phase of synthesized particle
with calcined at 800 for 2h. ZnTiO3, Zn2TiO4, Zn2Ti3O8, TiO2, ZnO. The average particle size
and distribution of the synthesized zinc titanate nanoparticles were below 100 nm and narrow,
respectively.
Testing System for Mechanical Behaviors Analysis and Cracking Resistance of Concrete at Early Age
Authors: Ma Xin Wei , Hooton Doug , Ou Jin Ping
Published: March 2009

A uniaxial experimental set-up was developed to evaluate the self-induced stresses,
visco-elastic strains and cracking potential of concrete from the time of its placement. The totally
restrained condition is achieved by keeping the length change within a threshold of 3μm. The
temperature rise of the specimens can be controlled within 1.5, by which the deformation because
of temperature change due to cement hydration could be prevented. The tensile force required to
compensate the shrinkage could be monitored and elastic strain and tensile creep can be calibrated
without an obvious interference of temperature deformation. The preliminary results testified the
workability of the system.
Measuring of Damage Parameters in Adhesive Bonding
Authors: Hilmy I. , Abdel Wahab M.M. , Ashcroft Ian A. , Crocombe A.D.
Published: March 2009

In this paper, the characterisation of damage in an epoxy adhesive has been investigated. Bulk
adhesive samples were used in this study for two reasons; firstly the stress distribution in the bulk
adhesive sample is simpler than that in a joint, secondly, the specimen’s dimensions meet fatigue test
specimen standards. Low cycle fatigue (LCF) tests with a load ratio of 0.1 and a frequency of 5 Hz
were performed on bulk adhesive dumbbell specimens. Damage curves, relating damage in the
specimen to number of cycles to failure, were plotted using an isotropic damage equation in which
damage is a function of stress, which decreases as damage progresses. The damage curves were then
fitted using a LCF damage evolution law. This equation was derived from a dissipation potential
function using Continuum Damage Mechanics (CDM) theory. Curve fitting was performed using a
Robust Least Square technique rather than ordinary linear least square because the damage curve has
extreme points (usually at the breaking point). Two damage parameters α and β were found from the
curve fitting process. This process resulted in different values of α and β for different stress levels.
The logarithmic α and β points were then plotted respect against stress level and linear regression
was used to determine α and β as a function of stress. With this function, damage parameters for
other stress level can be predicted.
Fracture Morphology and Residual Stresses of TiAl-Based Alloys Sheet Fabricated by EB-PVD
Authors: Zhang De Ming , Chen Gui Qing , Zhang Chun Mei , Han Jie Cai
Published: March 2009

The TiAl-based alloys sheet with 150 mm × 100 mm × 0.4 mm was fabricated successfully
by using EB-PVD method. The fracture morphology and residual stresses of the sheet were analyzed
by SEM, numerical calculation and X-ray stress analyzer. The results indicate that before stripping,
the depositional layers have a higher compressive stress, and the substrate has a very lower tensile
stress. For the isolated TiAl-based alloys sheet, the microstructure of as-deposited sheet is columnar
crystal, and the residual stresses distribution on the free surface has a trend that its magnitude
decreased gradually from center to edges. After vacuum annealing at 1273 K for 16 h, the columnar
crystal transforms into the equiaxed, the residual stresses on the free surface are eliminated ultimately,
and the fracture of the material is diverted from the manner of intergranular fracture to the mixed
manner of intergranular fracture with cleavage fracture.
Numerical Simulation on Failure Process of Internally Pressured Cylindrical Shell Subjected to Wedge Impact
Authors: Chen Gang , Zhang Qing Ping , Chen Zhong Fu , Li Si Zhong , Chen Yu Ze
Published: March 2009

Cylindrical shell is a kind of common used structure in engineering. Interest in the
response of cylindrical shells to local impact loading has increased over the last few years. A
structure always endures working load more or less. For a cylindrical shell, the working load
commonly is internally pressure. In this paper, a numeral simulation of wedge block impact
internally Pressured cylindrical shell was carried out. The dynamic failure process of the structure
was obtained. The consistency between experimental observation and numerical simulation is
satisfactory.