bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Electronic Conductive Silicon Nitride Ceramics by Convenient Powder Metallurgical Process
Authors: Kim Yoon Ho , Sekino Tohru , Kawaoka Hirokazu , Sung Rak Joo , Kusunose Takafumi , Nakayama Tadachika , Niihara Koichi
Published: March 2009

Si3N4 ceramics with V2O5 based glasses as sintering additives were successfully
fabricated by a powder mixing process and rapid sintering by the PECS method. The fabricated
materials by Pulsed Electric Current Sintering (PECS) exhibited very fine microstructure with α
and β grains. Electric conductivity for the Si3N4/(V2O5-B2O3) and the Si3N4/(V2O5-B2O3-Al2O3) at
room temperature were four and six orders of magnitude higher at room temperature, and two and
three orders of magnitude higher at 1000 oC than the conventional Si3N4, respectively
Electrically Conductive Aluminum Nitride Ceramics Containing In-Situ Synthesized Boron Carbonitride
Authors: Yoshikawa Jun , Katsuda Yuji , Yamada Naohito , Sakai Hiroaki
Published: March 2009

Electrically conductive AlN ceramics were fabricated by the addition of a small amount of
B4C and sintering aid, and hot-press sintering in a nitrogen atmosphere. The electrical resistivity of
AlN ceramics decreased remarkably from 1014 cm to the range of 100 to 102 cm by a minimum of
2.3 wt% of B4C addition. This resistivity decrease was caused by forming three-dimensional networks
composed of boron carbonitride (B-C-N) platelets synthesized during sintering. To produce the
networks of B-C-N platelets, two-step sintering with a heat-treatment step at 1600°C before the
densification step at 2000°C was needed.
Effect of Different Salt on Fabrication of Sr0.5Ba0.5Nb2O6 by Molten-Salt Synthesis
Authors: Chen Weiwu , Kume Shoichi , Duran Cihangir , Watari Koji
Published: March 2009

In the present work, effects of different salts (NaCl, 0.5NaCl-0.5KCl and KCl) on
molten-salt-synthesized Sr0.5Ba0.5Nb2O6 (SBN50) powder were explored. A variety of particle
morphology, compositions and lattice parameters of SBN50 were investigated. The results
showed that SBN50 particles synthesized in NaCl salt have the finest diameter (0.1-0.2μm) and the
highest aspect ratio (around 10), while the particles from 0.5NaCl-0.5KCl salt show the coarsest
diameter (0.2-0.3μm) and the lowest aspect ratio (around 5). If only using KCl salt, trace Sr2Nb2O7
normally co-exists with SBN50 phase. In addition, Na+ and K+ cations from salts are easily
incorporated with SBN structure and reach a very high content.
In-Situ Formation and Coating of Cordierite Whiskers on Cordierite Based Honeycomb Support
Authors: Jayaseelan Daniel Doni , Ueno Shunkichi , Kita Hideki , Kondo Naoki , Ohji Tatsuki
Published: March 2009

In this work, cordierite whiskers were successfully coated on cordierite honeycomb support by in-situ method. Whisker coating was performed on walls of the pore channels of cordierite support from aqueous slurry. Sintering was carried out at 1300 °C for 4 hours. XRD measurements revealed a complete formation of cordierite phase, no traces of other phases were identified. A well adherence of coating on the support was identified from the microstructure. SEM analysis also revealed the formation of three-dimensional network of cordierite whiskers with open pores between them on the cordierite support.
Fabrication of Porous Ni-ZrO2 for SOFC Using NiO-ZrO2 Composite Powders
Authors: Sato K. , Honda Sawao , Nishikawa T. , Awaji Hideo
Published: March 2009

Porous NiZrO2 has been widely used as anode in SOFC. However, it has been reported
that there was reduction in cell performance at high temperature since Ni grains in the porous Ni
ZrO2 sintered during cell operation. In this study, NiOZrO2 composite powders in which NiO
powder were covered with ZrO2 particles were prepared with controlled microstructure of porous
NiZrO2 which can prevent sintering of Ni grains during cell operation. NiOZrO2 composite
powders (HNZ) were prepared using NiO powder of high specific surface area and ZrO2 sol of
average particle size of 50 nm by ball milling (sol-coating method). SEM and EPMA analysis of
prepared NiOZrO2 composite powders showed that NiO particles were covered with ZrO2
particles. The crystallite phases, crystallite sizes, BET specific surface area of NiOZrO2
composite powders and porosities of fabricated porous NiZrO2 were characterized. SEM and
EPMA analysis showed that ZrO2 was distributed around Ni of a few μm range in the porous Ni
ZrO2 (HNZ) fabricated by the sol-coating method. Mechanical properties of porous NiZrO2
(HNZ) are required to be improved.
Transmission Electron Microscopic Study on Thermal Decomposition Process of Calcium-Deficient Hydroxyapatite
Authors: Tamai Masato , Nishio Koji , Isshiki Toshiyuki , Nakahira Atsushi
Published: March 2009

In our previous study, we reported that a metastable phase with high Ca/P molar ratio appeared in the temperature range from 700 οC to 800οC The purpose of this study is to investigate the crystallographic relationship between the metastable phase and HAp matrix. Ca-def HAp was annealed at 500-1000' ο C in air. High-resolution transmission electron microscopic (HRTEM) observations were performed along the [010], [110] and [001] zone axes in order to investigate the structure of the metastable phase. From HRTEM images and results of the analysis of selected area electron diffraction patterns along [010], [110] and [001] zone axes, the lattice constants of the metastable phase were analyzed into a=2.86nm, b=0.94nm, and c=0.69nm of an orthorhombic crystals system.
Pressure Sensing Using Electrostatic Capacitance
Authors: Bamba Noriko , Endo N. , Takagi T. , Fukami Tatsuo
Published: March 2009

Piezoelectric ceramic pressure sensors have been attracted great interest due to their
simple and miniature structure compared with conventional sensors such as strain gauge sensor. A
new type of static pressure sensor by using a change of permittivity upon applied mechanical
pressure has been studied in this work. BaTiO3 ceramics with/without a small amount of Mn were
used as sensing materials and the effect of poling treatment on their sensor performance was
investigated. An anti-ferroelectric material, NaNbO3, was also examined. All materials could
detect the change of pressure through the frequency shift of CR oscillator. Change of permittivity
of non-doped BaTiO3 and Mn doped BaTiO3 without poling treatment were larger than that of PZT
used as a reference, that is, BaTiO3 ceramics had higher-pressure sensitivity. BaTiO3 and relative
materials, however, needed transit time to reach the steady state, while NaNbO3 was independent to
the time. Conclusively, it seems that BaTiO3 and relative materials without poling treatment and
the anti-ferroelectric material, NaNbO3, become possible candidates as a pressure sensor using
permittivity change.
Microstructural and Electrical Characterisation of LaxBa1-xTi1-xYxO3 (0≦ x≦ 0.50) Ceramics
Authors: Feteira A. , Sinclair Derek C. , Lanagan M.
Published: March 2009

LaxBa1-xTi1-xYxO3 (0≤x≤0.5) powders were synthesised in air at 1400°C by the
conventional solid state method. According to the X-ray results, the tetragonal distortion in undoped
(x=0) BaTiO3 (space group P4mm) decreases with x and samples with x ≥0.05 show cubic
symmetry (space group Pm3m). For x≥0.05, the lattice parameter increases linearly with x, until
orthorhombic LaYO3 appears as a secondary phase for x>0.45. Dielectric properties of dense
(>95% of the theoretical X-ray density) ceramics were studied at both radio and microwave
frequencies. The permittivity maximum is shifted towards lower temperatures with increasing x and
a broad permittivity peak is observed for samples with 0.05<x<0.30. These samples exhibit a
dielectric response typical of “relaxor”-type materials. In contrast, ceramics with x=0.40 exhibit
almost temperature independent dielectric properties (τf=+12 ppm/K) and although they resonate at
microwave frequencies they have low quality factors (Q.f≤ 755 at ~5 GHz). Finally, conventional
transmission electron microscopy combined with electron diffraction studies were carried out to
provide a better understanding of structure-property relationships in LaxBa1-xTi1-xYxO3 ceramics.
Preparation and Properties of a Novel Anode of Interpenetrating Phase Composite Structure
Authors: Park Jun Young , Lee Jong Ho , Kim Joo Sun , Lee Hae Won
Published: March 2009

A novel Ni-YSZ anode with interpenetrating phase composite (IPC) structure was
developed using NiO-YSZ core-shell composite powder and evaluated in terms of microstructure,
electrical conductivity, thermal expansion and flexural strength. In comparison to conventional anode,
the anodic performance of IPC anode appeared to be more desirable for improving structural
reliability of SOFC unit cells and stacks. This study reveals that the anodic performance of IPC anode
can be readily tailored by controlling core-shell composite powder particles.
Low-Frequency High-Temperature Internal Friction in Ti-13Nb-13Zr Alloy
Authors: Niemeyer Terlize Cristina , Grandini Carlos Roberto , Schneider Sandra G.
Published: March 2009

Recent studies have been done to achieve biomedical alloys containing non-toxic elements
and presenting low elastic moduli. It has been reported that Ti-Nb-Zr alloys rich in beta phase,
especially Ti-13Nb-13Zr, have potential characteristics for substituting conventional materials such
as Ti-6Al-4V, stainless steel and Co alloys. The aim of this work is to study the internal friction (IF) of
Ti-13Nb-13Zr (TNZ) alloy due to the importance of the absorption impacts in orthopedic
applications. The internal friction of this alloy produced by arc melting was measured using an
inverted torsion pendulum with the free decay method. The measurements were performed from 77 to
700 K with heating rate of 1 K/min, in a vacuum better than 10-5 mBar. The results show a relaxation
structure at high temperature strongly dependent on microstructure of the material. Qualitative
discussions are presented for the experimental results, and the possibility of using the TNZ as a high
damping material is briefly mentioned.
Ultrasonic Attenuation Properties of Porous and Cellular Al Alloy with Spherical Pore
Authors: Tang Xiao Dong , Zhu Jin Song , He De Ping
Published: March 2009

Ultrasonic attenuation properties of two kinds of pored Al alloy were studied between
1MHz and 10MHz.. The results show that the ultrasonic attenuation properties are determined by
the pore structures of Al alloy. Ultrasonic attenuation coefficient α in porous Al alloy increases
with decreasing of pore diameter d, decreasing of porosity Ps , and increasing of specific surface
area Sv. However the α in cellular Al alloy increases with decreasing pore diameter d, increasing
porosity Ps and increasing specific surface area Sv. Ultrasonic attenuation property of cellular Al
alloy is better than that of porous Al alloy when they have the similar pore diameter d and
porosity Ps. The origin for different attenuation properties is discussed in these materials.
Electrode Properties of Dye Sensitized Solar Cell Using Ruthenium Complex/Titania Nano Crystal
Authors: Horikawa Hajime , Ogihara Takashi , Ogata Nobuo , Asahara Masahiro , Wu Xing Zheng
Published: March 2009

Titania nanocrystals were prepared by hydrolysis of titanium alkoxide in ethanol solution. The preparation of titania / alumina thin film was performed on ITO coated glass substrate by dip coating method using ethanol of titania nanocrystal and boemite sol. The crystal structures, microstructure and thickness of titania / alumina thin film were examined by XRD and SEM. The adsorption of dye was influenced by the surface structure of thin film. The adsorption of dye on the films was improved by the immersion into acid as HNO3. Ruthenium polypyridyl complex and triarylmethylium salt were used as dye. Electrode using titania / alumina thin film for dye-sensitized solar cell was constructed.
Oxygen Reduction Electrode Properties of Perovskite-Related Oxides Sr(Fe,Co,Ru)O3-δ at Low Temperatures
Authors: Chuma Takeshi , Toda Haruhiko , Saito Morihiro , Kuwano Jun , Shiroishi Hidenobu
Published: March 2009

The O2-gas electrode (OGE) properties of the perovskite-related oxides SrFe1-x-yCoyRuxO3 (SFCR) were examined with the solid-state cells of the type (SFCR | Ba0.975Ce0.8Gd0.2O3 | SFCR) below 300°C. The SrFe0.7Co0.2Ru0.1O3 electrode showed the best OGE properties of the other SrFe1-x-yCoyRuxO3 (x0.2) electrodes prepared here. An oxide-ion current of 200 μA/cm2 was allowed to flow through the cell with the SFCR electrode at 225°C. The SFCR electrodes including some other compositions can be used instead of conventional Pt electrodes in solid-state cells at temperatures below 300°C.
Electrochemical Behavior of LiFePO4 in Aqueous Lithium Hydroxide Electrolyte
Authors: Manickam Minakshi , Singh Pritam , Issa Touma B. , Thurgate Stephen , Prince Kathryn
Published: March 2009

The electrochemistry of olivine-type iron phosphate (FePO4) as a battery cathode material, in
aqueous lithium hydroxide (LiOH), has been investigated. The material forms intercalated LiFePO4
reversibly on electroreduction/oxidation. The formation of Fe3O4 phase, in addition to the
regeneration of FePO4 during reverse oxidation of LiFePO4, also occurs. In this regard, the
mechanism of FePO4 discharge/charge in aqueous LiOH differs from that in non-aqueous solvents.
Ferroelectricity of BiFeO3 Thin Films by Pulsed Laser Deposition and Effect of Atmosphere
Authors: Go Hyun Young , Wakiya Naoki , Satoh Keisuke , Kondo Masao , Cross Jeffrey S. , Maruyama Kenji , Mizutani Nobuyasu , Shinozaki Kazuo
Published: March 2009

In this study, BiFeO3 (BFO) epitaxial film was deposited on SrRuO3 (100)/SrTiO3 (100) substrates
using pulsed laser deposition (PLD). Phase pure BFO thin film was obtained. Introducing a mask
between the target and substrate in PLD improved the surface roughness from 47.8 nm (RMS,
without mask) to 7.7 nm (RMS, with mask). The composition and electrical properties of BFO thin
film were assessed after annealing for 1 h in Ar, N2, or O2 atmosphere at 600°C. The P-E hysteresis
properties improved only in the O2 atmosphere. After annealing under O2 atmosphere, the leakage
current decreased from 6.1 × 10-2 A/cm to 2.9 × 10-2 A/cm at 200 kV/cm, as in the other annealing
atmospheres, but 2Pr increased from 35 BC/cm2 to 50 BC/cm2.
Design of Femoral IM Nail by Analysis of Lateral Curve Angle
Authors: Kim Sung Min , Park Sung Yun , Lee Man Pyo , Choi Byong Cheol
Published: March 2009

In this study, the femoral cancellous bone angle is estimated in order to design the femoral
IM (Intra-Medullary) nail. Generally, it is various in size and curvature of femoral cancellous bone
depending on patient’s body dimension and surgeon has difficulty in fitting this femoral IM nail to the
patient in surgical procedure. In our study, Femoral lateral curve angle was estimated with more
precise method based on CT image of the femur and utilize this information is utilized for the design
of femoral IM nail for patients. Through this investigation, it may be possible to calculate each
patient’s femoral cancellous bowing angle more precisely. If the bowing angle of the lateral images of
each patient can be figured immediately through CT image, it will be easier to choose appropriate nail
that is most suitable for each individual. More investigations need to be achieved by collecting more
patient’s image data for femoral curvature.
The Effects of High-Heeled Posture on COP Kinematics and Muscle Fatigue during the Balance Control of Human Body
Authors: Choi Hyeon Ki , Cho Won Hak
Published: March 2009

This study addressed the effect of balance control problems on the high-heeled women. The specific purposes of this study are to quantify the displacements and velocities of center-of-pressure (COP) of a body during waist pulling perturbation and to compare the differences between the bare-feet and the high-heeled. Another purpose of the study is to identify the effects of a high-heeled posture on electromyography (EMG) activities and muscle fatigue. We used a waist pulling system which has three different magnitudes to sway the subjects. The COP displacement of a high-heeled posture was about twice as much as that of bare-feet posture. Also the COP velocity of a high-heeled posture became about twice as much as that of bare-feet posture. Muscle fatigue could be identified by the shift of the median frequency (MF) of the EMG power spectrum toward lower frequencies. Median frequency of the EMG power spectrum from tibialis anterior was reduced more rapidly during high-heeled situation than during bare-feet situation. COP kinematics and muscle fatigue analysis in postural balance researches are considered to provide useful information in understanding the balance control mechanism of women’s high-heeled posture.
Development of Spike Wavelet Analysis and Its Application to Damage Analysis on Gearbox
Authors: Lee Sang Kwon , Sim Jang Sun
Published: March 2009

Impulsive sound and vibration signals in gear system are often associated with their faults.
Thus these impulsive sound and vibration signals can be used as indicators in condition monitoring of
gear system. The traditional continuous wavelet transform has been used for detection of impulsive
signals. However, it is often difficult for the continuous wavelet transform to identify spikes at high
frequency and meshing frequencies at low frequency simultaneously since the continuous wavelet
transform is to apply the linear scaling (a-dilation) to the mother wavelet. In this paper, the spike
wavelet transform is developed to extract these impulsive sound and vibration signals. Since the spike
wavelet transform is to apply the non-linear scaling, it has better time resolution at high frequency and
frequency resolution at low frequency than that of the continuous wavelet transform respectively. The
spike wavelet transform can be, therefore, used to detect fault position clearly without the loss of
information for the damage of a gear system. The spike wavelet transform is successfully is applied to
detection of the gear fault with tip breakage.
Multi-Reference Scan-Based Nearfield Acoustical Holography
Authors: Kwon Hyuck Sang
Published: March 2009

Multi-reference, scan-based Nearfield Acoustical Holography (NAH) is a useful
measurement tool that can be applied when an insufficient number of microphones are available to
make measurements on a complete hologram surface simultaneously. The scan-based procedure can
be used to construct a complete hologram by joining together sub-holograms captured using a
relatively small, roving scan array and a fixed reference array. For the procedure to be successful, the
source levels must remain stationary for the time taken to record the complete hologram: that is
unlikely to be the case in practice, however. Usually, the reference signal levels measured during each
scan differ from each other with the result that spatial noise is added to the hologram. A
non-stationarity compensation procedure that is based on the acoustical transfer functions between
the sources and both the reference and scanning, field microphones are invariable is introduced.
Numerical and experimental results show well the availability of the introduced procedures to
suppress the spatially distributed noise and to get better sound fields partially separated.
A Correction of Geometric Error of Nano-Indenter Using Atomic Force Microscope and Finite Element Method
Authors: Baek Seung , Cho Sung Kuen , Seok Chang Sung
Published: March 2009

In this study, we investigated indentation behavior by varying the tip radius in a finite element model. We measured the tip radius and shape of the nano-indenter by SPM (scanning probe microscope) and compared them with the simulation results. The tip radius of cube corner indenter was measured to be 39nm, in agreement with the common tip radius of such indenters, which range from 20~50nm.
FE Analysis of Thermoelectric Cooler Using Bi-Te-Sb Compound Alloy
Authors: Han Seung Woo , Lee Myung Hee , Lee Hyun Woo , Yu Ji Hun , Ha Gook Hyun , Lee Kong Hoon
Published: March 2009

Bi-Te-Sb compound material was developed by spark plasma sintering process. The electrical, thermal, thermoelectric and mechanical properties also obtained by the experiments. This paper discusses performance and strength of the thermoelectric cooler made of Bi-Te-Sb compound alloy. The effect of the current has been investigated. The coefficient of performance (COP) is the primary factor to evaluate the performance of the coolers. Using the FEMLAB software package finite element (FE) analysis was carried out with properties of Bi-Te-Sb compound alloy from experiments. The temperature distributions, the stress distributions and the COP in the thermoelectric cooler were obtained.
Measurement of TiAlN Coating Effects on Machining Characteristics of High Hardened Steel
Authors: Won Si Tae , Jang Dong Young
Published: March 2009

Effects of TiAlN coating conditions on the cutting characteristics during machining high
hardened tool steel using coated ball end mill were studied in this research. KP4 steel and STD 11
steel were used as workpieces. Minimum quantity lubrication (MQL) was utilized in the cutting.
Scanning electron microscope, optical tool, and a tool dynamometer were used to measure coating
thickness and progress of tool wear. Results showed that the cutting distance using TiAlN coated
ball end mills was longer than that using WC-Co ball end mill by 2.3~5.7 times for KP4 steels and
about 2.5~4.3 times for STD11 heat treated steels. The multi layer TiAlN coated ball end mill
showed better performance of machining of hard steels than single layered coated tools.
The Influence of Microstructure and Chemical Composition on the Strength of Cast Iron Used for Railway Vehicles
Authors: Lee Young Min , Huh Yong , Park Jae Sil , Seok Chang Sung
Published: March 2009

Generally, the shape of graphite and the contents of elements strongly affect the tensile
strength of cast iron. In this study, hardness tests and tensile tests for the two types of gray cast iron
were carried out. The test results showed the similarity in the hardness but considerable difference in
the tensile strength between two materials. Microstructure analysis and chemical analysis were
conducted to determine the cause for the difference in the tensile strength between the two types of
cast iron. The experimental results showed differences in the microstructure and chemical
composition between the two materials. B-type brake disk material(B-type) that had higher tensile
strength includes flake, vermicular and spheroidal graphite, whereas A-type brake disk material
(A-type) included only flake graphite in the structure. Nodularity of graphite in the B-type was higher
than that in the A-type. Also, the B-type had the higher Si content and lower Mn content. In addition,
the B-type had Cu, while the A-type did not. Therefore, we concluded that the difference in the
strength between the two types of cast iron was due to the difference in the shape of the graphite and
the contents of Cu in the cast irons.
Durability Evaluations of the Car Body for Rubber-Tired Light Rail Vehicles
Authors: Kim Yeon Su , Jeong Rag Gyo , Lim Tae Kon , Hwang Won Ju
Published: March 2009

This study was aimed at evaluating the durability of the car body for rubber-tired light rail
vehicles according to Korean-standardized specifications for light rail vehicles (size, strength,
structure, weight, etc.). The strengths of the car body were analyzed under two weight conditions (tare
weight and maximum passenger weight) by using the finite element method. Based on the results of
the analysis, dynamic stresses were measured by using strain gauges, including rosette gauges, while
the train was running on the test track. Various experimental results have verified the durability and
safety of the car body.
Analysis of Vibration Caused by Ball Bearing in a HDD Spindle System at Elevated Temperature
Authors: Kim D.K. , Jang G.H.
Published: March 2009

This research investigates the vibration caused by ball bearing in a HDD spindle system,
specifically non-repeatable runout (NRRO), at elevated temperature by analyzing the characteristics
of ball bearing and the natural vibration characteristics of the spindle system due to the effect of
elevated temperature. It shows that the elevated temperature results in the decrease of bearing
deformation in the spindle system, which reduces the bearing stiffness and the natural frequencies of
the spindle system consequently. It has a significant effect on the amplitude and the frequency
distribution of NRRO at elevated temperature.
Evaluation of Shockproofness of Small Form Factor Mobile TFT-LCD
Authors: Kim Byung Sun , Lee Dock Jin , Koo Ja Choon , Choi Jae Boong , Kim Young Jin , Lee Jong Nam , Chu Young Bee
Published: March 2009

As the TFT-LCDs are getting more attention for the next generation display device,
specifications of the mechanical functionalities of the device is to be more tighter as well as the
electrical user specifications. Due to its brittle characteristics of TFT-LCD panels, maintaining
mechanical integrity under an impact loading situation is the one of the key design concerns.
Furthermore, as the TFT-LCDs are popularly adopted for various mobile equipments such as cellular
phones and digital cameras, shock failure of the display should be prohibitive for the design engineers.
A major incident being monitored during the shock loading is of course the local material failure of
the TFT-LCD panel that might happen at its maximum deformation. The present work delivers a
systematic approach for the shockproof design of mobile TFT-LCD. A specially designed shock test
setup evaluated by a set of rigorous FEM analyses is shown and comments for the shockproof method
is to be also delineated.
Velocity Feedback with a Non-Collocated Pair of Sensor and Actuator for Tip Vibration Suppression of a Beam
Authors: Lee Young Sup , Shin Ki Hong
Published: March 2009

This paper presents a theoretical and experimental study of a non-collocated pair of
piezopolymer PVDF sensor and piezoceramic PZT actuator, which are bonded on a cantilever beam,
in order to suppress unwanted vibration at the tip of the beam. The PZT actuator patch was bonded
near the clamped part and the PVDF sensor, which was triangularly shaped, was bonded on the other
part of the beam. This is because the triangular PVDF sensor is known that it can detect the tip
velocity of a cantilever beam. Because the arrangement of the sensor and actuator pair is not
collocated and overlapped each other, the pair can avoid so called "in-plane coupling", which can be
found at a matched piezoelectric sensor and actuator pair and restricts the stability and performance of
direct velocity feedback control. The test beam is made of aluminum with the dimension of 200 × 20
× 2 mm. Before control, the sensor-actuator frequency response function is confirmed to have a nice
phase response without accumulation in a reasonable frequency range of up to 5000 Hz. The feedback
control attenuates the magnitude of the first two resonances in the error spectrum of about 6 -7 dB.
Application of Fiber Optic BOTDA Sensor for Fire Detection in a Building
Authors: Kwon Il Bum , Kim Chi Yeop , Seo Dae Cheol
Published: March 2009

Smart structures are to be possessed many functions to sense the external effects, such as
seismic loads, temperature, and impact by some explosion, influenced on the safety of structures.
This work was focused on the development of a sensing function of smart structures to get the
temperature distribution on structures to detect fire occurrences. A fiber optic BOTDA (Brillouin
Optical Time Domain Analysis) sensor system was developed to detect the fire occurrence by
measuring the temperature distribution of a building’s exterior surfaces. This fiber optic sensor
system was constructed with a laser diode and two electro-optic modulators, which made this
system faster than systems using only one electro-optic modulator. The temperature distributed on
an optical fiber can be measured by this fiber optic BOTDA sensor. An optical fiber, 1400 m in
length, was installed on the surface of a building. Using real-time processing of the sensor system,
we were able to monitor temperature distribution on the building’s surfaces, and changes in
temperature distribution were also measured accurately with this fiber optic sensor.
Simultaneous Monitoring of Acoustic Emission and Corrosion Potential Fluctuation for Mechanistic Study of Chloride Stress Corrosion Cracking
Authors: Yonezu Akio , Cho Hideo , Ogawa Takeshi , Takemoto Mikio
Published: March 2009

Both the acoustic emission (AE) and corrosion potential fluctuation were monitored for
chloride stress corrosion cracking (SCC) of sensitized Type-304 stainless steel plate under bi-axial
stress states. Branched SCCs were produced from rectangular-shaped corrosion pits initiated by
falling-off of surface grains and filled with chromium oxide in 30mass% MgCl2 solution (363K).
Both the AE and potential fluctuation were simultaneously detected during pit formation and SCC
growth. Two types of AE (Type-I and Type-II) were monitored. Type-I AEs with higher frequency
components were detected during the pit growth and supposed to be produced by falling-off of surface
grains due to intergranular attack, while a number of Type-II AEs (approximately 12,500 counts) with
low frequency components were detected during SCC propagation and supposed to be produced by
cracking of the chromium oxy-hydroxides. Though the AEs detected during SCC test are not always
the primary AEs from the SCC itself, secondary AEs can be usefully utilized to monitor the SCC
initiation and propagation as well as the corrosion potential fluctuation.
Nondestructive Curing Monitoring of Early-Age Concrete Using Rayleigh Wave Velocity
Authors: Shin Sung Woo , Yun Chung Bang
Published: March 2009

A modified one-sided Rayleigh wave (R-wave) velocity measurement technique is applied
to monitor the strength gain of early-age concrete. A series of experiments were performed on
early-age concrete specimens with various curing conditions. The results show that the R-wave
velocity and strength gain has a strong relationship and that the R-wave velocity can be effectively
used to monitor the strength development of the early-age concrete.
Geomechanical Characterization of Faulted Rock Materials in Korea
Authors: Seo Yong Seok , Kim Chang Yong , Kim Kwang Yeom , Lee Kyoung Mi
Published: March 2009

A faulted rock usually shows the swelling behavior because of clay minerals which consist of the fault gouges. It makes rock mass unstable and threatens the safety of structures built in rock mass. This study was aimed at clarifying characteristics of physical and mechanical properties of faulted rock materials. At first, microstructures and mineralogical composition associated with faulting in the fault gouge zones were analyzed by using X-ray diffractometry (XRD) and SEM microphotographs. Physical properties of the faulted rock materials from fields were measured in the laboratory. It is well known that the mechanical properties are sensitive to the mineralogical assemblage and are affected by the shapes, distribution and preferred crystallographic orientation of the components. Material and direct shear tests were also conducted on faulted rock materials under saturated and unsaturated conditions. The mechanical results were analyzed together with the analyzed result of XRD and SEM.
Damage Assessment of Reinforced Concrete Beams by Complex Ratios of Transfer Functions
Authors: Yu Chih Peng , Cheng Chia Chi , Chiang Chih Hung
Published: March 2009

In this paper, a newly developed approach for the determination of characteristics
associated with local defects of a beam is briefly introduced. From the numerical studies carried out in
this study, the complex ratio between two transfer functions associated with an imaginary intact beam
and a damaged beam can provide such information. Based on the numerical studies, the rules in
determining degree of damages and locations of defects were first briefly outlined. These idealized
rules were then verified by experimental data obtained from dynamic tests of realistic specimens of
simply-supported reinforced concrete beams. The preliminary results indicate that the defined ratio of
transfer functions can potentially serve as an exaggerated indication for the degree of changes in
certain modal responses. Thus, the proposed ratio of transfer functions can be used to assist system
identification, while the nature of high sensitivity also restricts its direct application to certain
complicated data associated with field tests. A variety of test setup for both receivers and impact
sources were studied and the test results appear to agree with designated conditions of the specimens.
Crack Detection by Static Measurement in Steel Beams
Authors: Park Philip , Huh Yong Hak , Kim Dong Jin , Son Byung Jik
Published: March 2009

Effects of crack on static behavior in steel box girder were investigated to identify the
possibility of crack detection and location using conventionally measured static data including
deflection and inclination. Finite element analysis with finely meshed 3-D models and experiments
were performed for steel box girder with crack. To eliminate the variation according to load
magnitude, compliance technique was applied to analysis of the result. Through this study, the
quantitative relationship between crack size and structural responses of deflection and inclination
were obtained as a form of relation-curve. This relation-curve can be utilized to evaluate crack size in
the steel box girder bridge. The results also demonstrated that the location of crack can be estimated
by static measurement.
Development of On-Line Health Monitoring System for Pipes in Nuclear Power Plants
Authors: Eom Heung Seop , Lim Sa Hoe , Kim Jae Hee , Kim Young H. , Kim Hak Joon , Song Sung Jin
Published: March 2009

This study was aimed at developing an effective method and a system for on-line health
monitoring of pipes in nuclear power plants by using ultrasonic guided waves. For this purpose we
developed a multi-channel ultrasonic guided wave system for a long-range inspection of pipes and a
few techniques which can effectively find defects in pipes. To validate the developed system we
performed a series of experiments and analyzed the results.
Integrated Approach for On-Line Condition Monitoring of Piping
Authors: Kim Jung Taek , Seong Seung Hwan , Park J.H. , Cheon S.W. , Lee C.K. , Lee Na Young , Hwang Il Soon , Lee Sang J.
Published: March 2009

There are several efforts for an advanced on-line health monitoring of a piping system by
using a chemical condition monitoring, a X-ray radiography and a ultrasonic techniques. In order to
increase the confidence of the understanding on the health condition of the underlying piping system,
an integrated and multi-disciplinary approach has been adopted in this paper. Flow-Accelerated
Corrosion (FAC) under an undesirable combination of the water chemistry, flow velocity and material
composition has usually caused a pipe wall thinning. The condition monitoring tests on a piping
elbow of a piping system have been conducted by using several advanced sensors such as an
accelerometer, ultrasonic device, and chemical sensors.
Fault Detection Using Acoustic Methods for the Sodium-Water Reaction Monitoring in a Liquid Metal Reactor
Authors: Hur Seop , Seong Seung Hwan , Kim Seong O , Lee Sang J.
Published: March 2009

This study was aimed at developing a new method for detecting the sodium-water
reaction as a result of a water leakage into the liquid sodium boundary for the liquid metal reactor.
In the case of a passive acoustic method, to develop the leak detection algorithm, several signal
processing methods have been evaluated. When the acoustic emission signal has a relatively high
signal-to-noise ratio for the acoustic noises the spectral estimation method could be used to detect
the sodium water reaction. In the case of a low signal-to-noise ratio within -5 dB to -15 dB, the
system modeling and the identification methods using an autoregressive and an adaptive algorithm
could be used to detect the sodium-water reaction. Regarding the active acoustic method, the basic
attenuation factors of the ultrasonic beam were evaluated in the case of normal and abnormal plant
conditions.
Evaluation of Fracture Toughness for Power Plant Materials Using Continuous Indentation Technique
Authors: Lee Jung Suk , Jang Jae Il , Yoo Keun Bong , Kwon Dong Il
Published: March 2009

An indentation fracture toughness model is applied to estimate non-destructively the
fracture toughness of power plant materials such as ASTM A53 and ASME SA335 P91. Fracture
toughness evaluated using the model showed good agreement with current standard fracture
toughness test results.
Fatigue Life Prediction of Heat-Aging Vulcanized Natural Rubber
Authors: Woo Chang Su , Kim Wan Doo
Published: March 2009

Heat-aging effects on the material properties and fatigue life prediction of natural rubber
were experimentally investigated. The rubber specimens were heat-aged in an oven at the temperature
ranging from 50oC to 100oC for a period ranging from 1 day to 90days. Fatigue life prediction
methodology of vulcanized natural rubber was proposed by incorporating the finite element analysis
and fatigue damage parameter determined from fatigue test. Fatigue life prediction equation
effectively represented by a single function using the Green-Lagrange strain. Predicted lives are in a
good agreement with the experimental lives within a factor of two
Fracture Toughness with Thermal Aging in CF8M/SA508 Welds
Authors: Woo Seung Wan , Kwon Jae Do , Choi Young Hwan
Published: March 2009

In a primary reactor cooling system, a dissimilar weld zone exists between cast stainless steel (CF8M) in a pipe and low-alloy steel (SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and 330, while no effect is observed in SA508 cl.3. The aged specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at 430, respectively. The specimens for elastic-plastic fracture toughness tests are prepared two types, which notch is created in the center of deposited zone and the heat affected zone of CF8M. From the experiments, the plastic-elastic fracture toughness values (JIC) with the increase of aging time decrease as the notch is created in the HAZ of CF8M, while that is different slightly as the notch is created in the deposited zone. Also, JIC values in the deposited zones are smaller than the HAZ of CF8M at all aged specimens.
Influence of Inclusion on Deformation of Crack Tip in Rotating Disc by Photoelasticity and Method of Caustics
Authors: Ezumie Tsutomu , Nishimura Kentaro
Published: March 2009

Fatigue and fractures such as blades and discs, which originate in the centrifugal force caused in the rotor, become factors that often cause serious accidents. The enlargement of machine and structure improves the possibility that do the latency of minute cracks and inclusion in materials in manufacturing processes. Severe working conditions also promote the propagation of the crack while operating. Thus, it is very important for the improvement in the safety of materials to analyze the interference problem of inclusion and crack. In this study, an inclusion in the rotating disc and the interference problem of the crack were examined. The influence of the mechanical property of the inclusion and the distance to the crack tip was examined. The stress intensity factor was determined by using photoelasticity and method of caustics. As a result, the stress intensity factor was decreased when Young’s modulus of inclusion increased. Moreover, the stress intensity factor decreased as the distance from the crack tip to the inclusion boundary became longer. The stress intensity factor of the crack on the rotation center side increased more than the cracks on the circumference side of the inclusion.
Study on Stress Intensity Factor under Torsion Load of Double Column for Two Dissimilar Materials
Authors: Sasaki Syuutei , Ezumie Tsutomu
Published: March 2009

The stress analysis of the double column made of the dissimilar material is not enough reported the problems about the interface of the crack on the surface. These products are guaranteed for the high performance, and are composed of the dissimilar material or composted to the new material or composed to the new materials again by the compound of the material and the advancement of joint technology. The Stress Intensity Factor K, Kand K usually act in single or mixed modes. The separation of K, Khas already been achieved. In this paper, an experimental technique for determining the stress intensity factor Khas been presented by using the method of reflected caustics in combination with the stress freezing method. The experimental model is a cylindrical bar with w radial crack along the direction of the axis under the load of pure torsion. In order to obtain a caustic pattern, a slice cut from the frozen model is annealed, and evaluated it for the stress intensity factor in a double column of the different kind material by the experiment analysis.
A Computational Tool for Defect Analysis in Rail with Ultrasonic Guided Waves
Authors: Lee Chong Myoung , Rose Joseph L. , Luo Wei , Cho Youn Ho
Published: March 2009

Rail represents one of the most important means of transportation. Many nondestructive
testing methods have been used to find defects in rail. The guided wave technique is the most
efficient because of its long propagation characteristic along the rail. Potential for detecting
transverse cracks exists whereas standard bulk wave technique could miss the cracks. The wave
structure of the rail cross-section for a particular loading condition of modes and frequencies is an
important feature. In this paper, the propagation and scattering patterns of guided waves in a rail are
studied using finite element methods. The wave structures are also examined. Various multiple
defect situations and rail boundary conditions can also be studied.
The Collapse Characteristics of CFRP Hat-Shaped Section Members under Axial Compression
Authors: Lee Kil Sung , Yang In Young
Published: March 2009

The front-end side members of automobiles, such as the hat-shaped section member,
absorb the most of the energy during the front-end collision. The side members absorb more energy in
collision if they have higher strength and stiffness, and stable folding capacity (local buckling). Using
the above characteristics on energy absorption, vehicle should be designed light-weight to improve
fuel combustion ratio and reduce exhaust gas. Because of their specific strength and stiffness, CFRP
are currently being considered for many structural (aerospace vehicle, automobiles, trains and ships)
applications due to their potential for reducing structural weight. Although CFRP members exhibit
collapse modes that are significantly different from the collapse modes of metallic materials,
numerous studies have shown that CFRP members can be efficient energy absorbing materials. In this
study, the CFRP hat-shaped section members were manufactured using a uni-directional prepreg
sheet of carbon/Epoxy and axial collapse tests were performed for the section members. The collapse
mode and the energy absorption capability of the section members were analyzed under the static
load.
Analysis of Dominant Frequencies of Glass Fiber/Aluminum Laminates during Acoustic Emission Measurement
Authors: Woo Sung Choong , Choi Nak Sam
Published: March 2009

Dominant frequency characteristics of acoustic emission (AE) from single-edge-notched
(SEN) glass fiber aluminum laminates (GFAL) under tensile loads were analyzed in relation to
fracture mechanisms. The first and second peak frequencies expressed the characteristic changes of
fracture processes in SEN-GFAL specimens such as macro-crack propagation and/or delamination
between aluminum and fiber layers. On the basis of the above frequency analysis and of the fracture
observation with ultrasonic through-scan and various microscopes, characteristic models for crack
propagation of SEN-GFAL was proposed according to various orientations of fiber layer.
Widespread Fatigue Damage – An Issue for Aging and New Aircraft
Authors: Horst Peter
Published: March 2009

Widespread Fatigue Damage (WFD) is a technical expression used in the certification of
aircraft. The paper presents a set of issues which may influence the probability that a structural item
exhibits WFD. The paper mainly follows the line of a stochastic approach to these subjects, and
includes the influence of realistic parameters - like manufacturing - and tries to assess what may be
the impact of new technologies.
Studies of Fuel-Air Mixture Explosion Characteristics and Structure Fracture and Damage in Large-Scale Metal Oil Storage Tank
Authors: Du Yang , Gao Jian Feng , Jiang Xin Sheng
Published: March 2009

The fuel-air mixture explosion incidents in the large-scale metal oil storage tank are frequent
occurrence and rapidly extend because of the tank structure being fractured and damaged by the fuel-air
mixture explosion. In this paper, the simulation experiment and numerical simulation has been carried out for
the fuel-air mixture explosion in the large-scale metal storage tank. The shock waves characteristic of the
explosive pressure has been studied and discussed. The fracture and damage effects caused by the shock
waves characteristic to the tank structure has been analyzed and discussed too.
Experimental Investigation on Mode II Fracture Toughness KIIC of Concrete and Fracture Behavior
Authors: Xu Shi Lang , Gao Hong Bo , Zhang Xiu Fang
Published: March 2009

Using the double-edge notched geometry proposed by Xu and Reinhardt recently, the
dimension of 200 mm×200 mm×100mm concrete cube specimens, of which the crack length are 10
mm, 20 mm, 30mm, 40mm, 50mm respectively, are designed to experimentally measure mode II
fracture toughness KIIC of concrete. For almost all specimens, typical shear fracture features i.e.
approximately 0º initial cracking angle as well the following crack forwards propagation along the
direction of ligament is phenomenally observed. This fact strongly confirms that this double-edge
notched geometry is validly and capable of being utilized as a mode II fracture geometry to evaluate
mode II fracture behavior. Then, from the discontinuity point of the measured load-displacement plot,
the critical shear fracture load Pc is determined and the corresponding mode II fracture toughness KIIC
is also calculated using the formula developed by Xu and Reinhardt. The computed results show that
KIIC has no dependency on initial crack length, about 3.36MPa·m1/2 for the tested specimens.
Study on Generalized Fatigue Damage under Random Loading
Authors: Chen Zhi Wei , Wu Jian Gang
Published: March 2009

Generalized fatigue damage is derived based on S-N curve under constant amplitude loads with S characterizes the load cycle by the combination of load peak and load amplitude. For random fatigue loads, a natural choice is to use half cycle (Range) counting method. Rain Flow counting is popular due to its useful nature to pick-out full cycles among random loads. It is found in the present research through analysis and verified by experimental results that Rain Flow counting seriously overestimate the damage for the actual true random loads owing to its inherent nature and the Range counting method is more reliable. As the filtering threshold increases gradually, the overestimation effect by Rain Flow counting method becomes less, and the calculated damages by Rain Flow and Range counting begin to converge. The filtering threshold damage corresponding to the “fatigue limits” for the concerned case was calculated. According to equal damage principle, the filtering threshold amplitudes were derived and found to vary with the load peaks. In practice, an acceptable solution is to use quasi-variable filtering thresholds.