bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Liquid Phase Sintered SiC Ceramics with Oxide Additive Materials
Authors: Lee Sang Ll , Shin Yun Seok , Lee Jin Kyung , Lee Joon Hyun , Park Jun Young
Published: March 2009

This paper dealt with the fabricating process of liquid phase sintered (LPS) SiC ceramics
containing the oxide additives of Al2O3 and Y2O3, in conjunction with the evaluation of their
mechanical properties. LPS-SiC ceramics was sintered at the temperature of 1820 oC under an
applied pressure of 20 MPa and a pressure holding time of 2 hour. A commercial SiC powder with
an average size of about 0.3 μm was used as a starting powder. LPS-SiC ceramics with additive
composition ratios of 1.5 and 2.3 (Al2O3/Y2O3) represented an excellent density of about 3.2 Mg/m3.
LPS-SiC ceramics had a flexural strength of about 800 MPa and a fracture toughness of about 8.0
MPa⋅m0.5 at an additive composition ratio (Al2O3/Y2O3) of 1.5.
Accelerated Life Testing Method of Transmission
Authors: Kim Hyoung Eui , Kim Doh Sik , Lee Yoon Pyo , Yoo Yung Chul
Published: March 2009

In this study, we proposed a process of an accelerated life testing method of 5-speed
manual transmissions used in vehicles, which loads are consisted of multiple alternating loads. The
entire process of an 5-speed manual transmission’s accelerated life testing method where no failures
are allowed, is a process that requires an abundance of assumptions, and other factors that are
estimates such as the shape parameter, beta() and the fatigue damage exponent (x). And the
process is consisted of 7-step process. From the 1-setp, which is the deriving the service(use) torque
and speed(rpm) profile of the transmission, to the 7-step, we could determine the accelerated life
time, the accelerated torque and the accelerated speed(rpm), which are the equivalent cumulative
fatigue damage. Also, we have performed accelerated life test on 5-speed manual transmission by
using the following 7-step process.
Inverse Method to Determine Mechanical Properties of Thin Film by Nanoindentation and Finite Element Analysis
Authors: Baek Dong Cheon , Lee Soon Bok
Published: March 2009

As a reliable tool to measure the Young’s modulus, nanoindention technique has been
used widely recently. In this paper, nanoindetation technique was overviewed with its advantage
and limitation and a new method was proposed to determine material properties of film, i.e. both
Young’s modulus E and Poisson’s ratio ν from load-displacement curve of shallow-depth
indentation using ‘inverse method’.
Correlation between Microstructure and Nanohardness in Advanced Heat-Resistant Steel
Authors: Jang Jae Il , Shim Sang Hoon , Komazaki Shinichi , Sugimoto Takayuki
Published: March 2009

As advanced ferritic/martensitic heat-resistant steels generally have a complex structure
consisting of several microstructural units (lath, block, packet, and prior austenite grain), it is very
hard to separate the contribution of each microstructural unit (or its each boundary) to the
strengthening mechanism in such steels. Here we explore the role of each microstructural unit in
strengthening of advanced high Cr steel through nanoindentation experiments performed at
different load levels. Nanoindentation results are analyzed by comparing with microstructural
observations and discussed in terms of prevailing descriptions of strengthening mechanism.
Holding Capacity of a Dielectrophoretic Barrier for Microparticles
Authors: Chen Da Feng , Du He Jun , Li Wei Hua , Gong Hai Qing
Published: March 2009

A dielectrophoretic barrier is generated with two layers of microelectrode structures so
called paired electrode array (PEA) constructing face to face on the top and bottom sides of a
microchannel. The barrier is designed to control the movement of particles in combination with a
fluid flow. Depending on the relative strength of the DEP force and hydrodynamic force,
microparticles or cells carrying by a laminar flow can either penetrate the barrier or be deflected
from there. The threshold velocity at which the barrier firstly fails to hold back the particles is a
significant parameter to validate the performance of the device. This paper presents an experimental
study on the performance of the microfabricated paired electrode array. The electrodes were
fabricated with conventional microfabrication techniques. Micron-sized latex beads were used in
the investigation. The holding capacity was defined by measuring the threshold velocity of the
system. The results provide crucial information for the design of the dielectrophoretic barrier for
microparticle manipulation and separation.
Study on the Lateral Piezoelectric Actuator with Actuation Range Amplifying Structure
Authors: Lee Taik Min , Seo Young Ho , Whang Kyung Hyun , Choi Doo Sun
Published: March 2009

A novel piezoelectric micro-actuator with actuating range amplification structure has
been proposed. This actuator is unique in that the leverage type amplification structure enables large
actuating movement with low voltage. In case of general piezoelectric thin film actuator, applied
voltage is low and almost zero power is consumed. Its switching time is very fast in comparison
with electrostatic actuators and thermal actuators. However, the most drawback of piezoelectric
actuator is short actuating range. A 100μm length PZT actuator can only make movement of 100.
In this research, we suggest an actuator which can provide geometric amplification of the PZT
strain displacement in lateral direction. The lateral piezoelectric MEMS actuator was fabricated and
its actuating range was measured. The actuator shows maximum lateral displacement of 1.1μm, and
break-down-voltage of the thin film PZT actuator is above 16V.
The Influence of the Temperature Increase on the Tribological Behavior of DLC Films by RF-PECVD
Authors: Cho Yong Kyung , Jeon Hong Gyu , Cho Dae Hyun , Lee Young Ze
Published: March 2009

DLC (Diamond Like Carbon) films show very desirable surface interactions with high
hardness, low friction coefficient, and good wear-resistance properties. The friction behavior of
hydrogenated DLC film is dependent on tribological environment, especially surrounding
temperature. In this work, the tribological behaviors of DLC (Diamond-like carbon) films, prepared
by the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, were
studied in elevated temperatures. The ball-on-disk tests with DLC films on steel specimens were
conducted at a sliding speed of 60 rpm, a load of 10 N, and surrounding various temperatures of 25,
40, 55 and 75. The results show considerable dependency of DLC tribological parameters on
temperature. The friction coefficient decreased as the surrounding temperature increased. After tests
the wear tracks of hydrogenated DLC film were analyzed by optical microscope, scanning electron
spectroscopy (SEM) and Raman spectroscopy. The surface roughness and 3-D images of wear track
were also obtained by an atomic force microscope (AFM).
A Study on Automation Program for the Characteristics Improvement of Optical Element Alignment System
Authors: Jeong Sang Hwa , Kim Gwang Ho , Cha Kyoung Rae
Published: March 2009

With the increasing demand for VBNS and VDSL, the development of the kernel parts of
optical communication such as PLC(Planar Light Circuit), Coupler, and WDM elements has
increased. The optical transmitter and the receiver module need precise and mechanical alignment
within a few micrometers to couple the semiconductor device, optical fiber and waveguide. The
alignment and the attachment technology are very important in the fabrication of an optical element.
Presently, the alignment of the optical element is time consuming, and an effective alignment
algorithm has not yet to be developed. In this paper, the optical element alignment of the multi-axis
ultra precision stage is studied. Two alignment algorithms applied to the ultra precision multi-axis
stage are used, the field search algorithm and the peak search algorithm. The automation program to
improve the characteristics of the optical element alignment system is developed by Labview
programming and is composed of three tabs, the field search tab, plotting tab and peak search tab.
The developed program is applied to an actual system to determine the improvement in alignment
performance.
Equal Channel Angular Pressing of Carbon Nanotube Reinforced Metal Matrix Nanocomposites
Authors: Pham Quang , Jeong Young Gi , Hong Soon Hyung , Kim Hyoung Seop
Published: March 2009

In this study, powder processing and severe plastic deformation (SPD) approaches were
combined in order to achieve both full density and good particle-matrix bonding in CNT and Cu
powder mixtures without grain growth, which was considered as a bottle neck of the bottom-up
method in the conventional powder metallurgy of compaction and sintering. Equal channel angular
pressing (ECAP), one of the most promising methods in SPD, was used for the powder
consolidation. The powder ECAP processing with 1, 2, 4 and 8 passes was conducted at room
temperature. It was found by microhardness tests and microstructure characterization that relatively
high mechanical strength could be effectively achieved as a result of the well bonded powder
contact surface during powder ECAP. The SPD processing of powders is a viable method to
achieve both fully density and good particle bonding in CNT-metal matrix nanocomposites.
Tensile Test of Individual Multi Walled Carbon Nanotube Using Nano-Manipulator inside Scanning Electron Microscope
Authors: Jang Hoon Sik , Kwon Sung Hwan , Kim Am Kee , Nahm Seung Hoon
Published: March 2009

We have attempted to observe straining responses of an individual multi-walled carbon
nanotube (MWNT) by performing an in-situ tensile testing inside scanning electron microscope
(SEM). The both ends of an individual MWNT was attached on the rigid support and the tip of the
force sensor using electron beam and was elongated by a nano-manipulator. The nano-manipulator
was automatically controlled by personal computer. Linear deformation and fracture behaviors of
MWNT were successfully observed and its force-displacement curve was also measured from the
bending stiffness and displacement of the force sensor and manipulator. The tensile properties of
individual MWNT were evaluated from the tensile test results.
A New Six-Step Phase Shifting Technique Using Mixed-Polariscope in Digital Photoelasticity
Authors: Ramji Manoharan , Ramesh K.
Published: March 2009

Photoelasticity is one of the most widely used techniques for experimental stress and
strain analysis. With the availability of low cost digital image processing systems, a separate branch
of photoelasticity known as digital photoelasticity came into existence providing whole-field values
of the isoclinics (θ) and isochromatics (N) in a true sense. Among the several methods available for
data acquisition, phase shifting / polarization stepping techniques are most widely used for their
simplicity and accuracy. In this paper a new digital photoelastic method based on phase shifting
using monochromatic light source is presented. It provides full field values of θ and N. The
arrangement is carefully chosen with the intention of reducing the influence of quarter wave
mismatch error in the evaluation of θ and N. The methodology is validated for the benchmark
problem of a disk under diametral compression.
Scanning Tunneling Microscopy Studies of Porous and Oxidized Zn
Authors: Chang Sung Sik , Sakai Akira
Published: March 2009

This paper reports the scanning tunneling microscopy (STM) and scanning tunneling
spectroscopy (STS) studies of porous Zn (p- Zn) prepared by electrochemical etching. Further, the
post annealing of the p- Zn is carried out and STM/STS investigations are also performed. STM
studies of these samples reveal the porous structure and display small, pseudo-spherical shaped
crystals in the range of 2 and 100 nm, 2 and 50 nm, and similar average corrugation of 9 nm for p-
Zn and oxidized p-Zn. STS analysis of freshly prepared p- Zn shows a band gap of 2.4 eV along
with metallic conductance behavior. However, oxidized p- Zn reveals a distinct wide band gap (3
eV) and shows shallow donor states near the conduction band.
Force Measurement by AFM Cantilever with Different Coating Layers
Authors: Yeh Meng Kao , Chen Bo Yi , Tai Nyan Hwa , Chiu Chien Chao
Published: March 2009

Atomic force microscopy (AFM) is widely used in many fields, because of its
outstanding force measurement ability in nano scale. Some coating layers are used to enhance the
signal intensity, but these coating layers affect the spring constant of AFM cantilever and the
accuracy of force measurement. In this paper, the spring constants of rectangular cantilever with
different coating thickness were quantitatively measured and discussed. The finite element method
was used to analyze the nonlinear force-displacement behavior from which the cantilever’s normal
and torsional spring constants could be determined. The experimental data and the numerical results
were also compared with the results from other methods. By considering the influence of coating
layers and real cantilever geometries, the more accurate force measurements by AFM cantilever can
be obtained.
Electro-Chemical Mechanical Deposition for Planarization of Cu Interconnect
Authors: Jeong Suk Hoon , Seo Heon Deok , Park Boum Young , Park Jae Hong , Park Sung Min , Kim Sang Chul , Kim Kee Ho , Jeong Hae Do
Published: March 2009

As copper technology moves from pilot to volume manufacturing, semiconductor
fabrication is focused on methods to improve device yield. In especially semiconductor
manufacturing, electrochemically deposited copper is the material of choice for advanced
interconnect applications. Electrochemical deposition (ECD) employs copper plating electrolytes
with organic additives to achieve bottom-up filling of small vias and trench with high aspect-ratios.
However, for features with small aspect-ratios, the ECD process yields conformal layers because
the additives and the bottom-up fill mechanism are not operative in such large features. So, ECD
process does not achieve within-die and within-wafer planarity of the deposited copper layer. For
planarization of large features and obtaining globally and locally flat films, an electro-chemical
mechanical deposition (ECMD) method has been employed. ECMD process is a novel technique
that has ability to deposit planar conductive films on non-planar substrate surfaces. Technique
involves simultaneous ECD roles and mechanical sweeping of the substrate surface. Copper layer
deposited by the ECMD process grows preferentially in cavities on the wafer surface yielding flat
profiles and much reduced overburden thickness. Preferential deposition into the cavities on the
substrates surface may be achieved through two different mechanisms. The first mechanism is more
mechanical in nature and it involves material removal from the top surface. The second mechanism
is more chemical in nature and it involves enhancing deposition into the cavities where mechanical
sweeping does not reach, and reducing deposition onto surfaces that are swept. Planar layers
obtained by the ECMD technique are suitable for low stress material removal processes. Planar
layers also yield improved parametric results in device structures after the material removal step. In
this study, we demonstrate mechanical role of pad gives effects in ECMD process. So we evaluate
gap-filling and planarization between ECMD and ECD.
The Electrospinning Process and Mechanical Properties of Nanofiber Mats under Vacuum Conditions
Authors: Hur Shin , Kim Wan Doo
Published: March 2009

The structure and morphology of the electrospun nanofiber depend on the parameters
such as the physical properties of polymer, the applied voltages, tip to collector distance and
ambient condition. Until now, most of studies have been focused on the effects of the above
mentioned parameters for electrospinning process. But the study on vacuum conditions in
electrospinning process almost not exists. The goal of this study is to investigate the effects of
vacuum conditions in electrospinning process. The setup of electrospinning device is installed
within homemade vacuum chamber. The polymer jets are ejected from a multi-spinneret connected
with a microsyringe pump towards the collector located at fixed distance from the needle tip under a
vacuum condition. The nanofiber mats are fabricated using a rotating collector. The visualization
and imaging system of electrospinning process are consisted of a green laser devices, microscope,
CCD camera and image recording device. During the electrospinning process, the behaviors of
nanofiber are visualized and analyzed by this system. The morphologies and dimensions of
electrospun fiber mat are measured with SEM. As a final result, the vacuum conditions of
electrospinning process influence the behaviors of nanofiber.
Microstructural Characterization of Al-Zr Alloy with Nano-Sized Grains
Authors: Kim Il Ho , Kim C.S. , Kim K.T. , Kim Yong Hwan
Published: March 2009

The mechanical alloying processes was employed to fabricate Al-4at.%Zr alloy with
nano-sized grains and very fine Al3Zr compounds. The phase transformations and the stability of
the phases formed during mechanical alloying and heat treatment processes were investigated. The
grain sizes of the alloys immediately after milling and following the subsequent heat treatment at
550°C were 54.2nm and 106.4nm, respectively. Some of Zr atoms were dissolved into the Al
matrix and most of them reacted with hydrogen produced by decomposition of PCA(process control
agent) to form ZrH2 during mechanical alloying process. These ZrH2 hydrides decomposed
gradually after the heat treatment. Stable Al3Zr with a DO23 structure was formed by heat treatment
at temperature of more than 4500C. The hardness of the Al-4at.%Zr alloy was more than two times
higher than those of other Al-based alloys.
Investigation of Effect of Grains on Deformation of Wood under Shearing Loads Using Electronic Speckle Pattern Interferometry
Authors: Umezaki Eisaku
Published: March 2009

The two-dimensional deformation of wood with different grains under shearing loads
was measured using an electronic speckle pattern interferometry (ESPI) technique. The radical,
tangential and end sections of Douglas firs (Pseudotsuga menziesii) were used as specimens.
Results revealed that the deformation values significantly vary for every part of the specimens, and
the ring directions of earlywood and latewood, which compose the annual rings, have an effect on
the two-dimensional deformation of wood.
Site Experiment for Predicting Hazardous Geological Formations ahead of Tunnel Face
Authors: Lin C.N. , Jiao Yu Yong , Liu Q.S.
Published: March 2009

In the construction of railways in western part of China, more and more long tunnels have
been excavated these years, and several ones are under construction at the moment. Because of the
complex geologies like faults, fractured zones, karst cavities as well as water bearing formations, the
stability and safety of tunnels have been challenging topics in the construction process. In this regard,
the advance knowledge of the location, size, and spatial information of the uncertainties ahead of the
face is very important to the contractors. In this paper, by using the Tunneling Seismic Prediction
(TSP) technique, site experiments are performed to predict hazardous formations ahead of face in a
railway tunnel. Through interpretation of the testing data, the wave velocities and the mechanical
parameters of the surrounding rock are obtained, and the faults/fractures are recognized. The study
shows that compared to time-consuming core drilling method, the wave reflection based TSP method
can predict major uncertain formations in long range ahead of the face in short time. The downtime, as
we know, is one of the key factors in speeding the tunnel construction. For the prediction accuracy, the
TSP technique is able to provide enough information due to its multiple proof-test procedure.
An Indentation Method Based on FEA for Equi-Biaxial Residual Stress Evaluation
Authors: Lee Jin Haeng , Lee Hyung Yil
Published: March 2009

An indentation method to determine equi-biaxial residual stress is proposed by examining
the data from the incremental plasticity theory based FE analyses. We found that hardness is strongly
dependent of the magnitude and sign of residual stress and material properties. We then selected some
normalized parameters minimally affected by material properties and tip radius. With numerical
regressions of the data obtained, we proposed new formulae for residual stress evaluation. The new
approach provides a substantial enhancement in accuracy compared with the prior methods.
Using Data Mining Techniques for the Management of Seismic Vulnerability
Authors: Leon Florin , Atanasiu Gabriela Maria , Gâlea Dan
Published: March 2009

Natural hazards, and especially earthquakes, are often recurring phenomena. Therefore,
there is a permanent need for solutions to reduce earthquake losses by developing technologies,
procedures, knowledge, and tools for seismic design and rehabilitation of buildings and
infrastructure. A key point to an effective decision making process that aims at mitigating their
effects is building a model of the underlying facts. A Geographical Information System (GIS) is a
framework able to assemble, keep, process and display specific information, identified by
geographical location, which can combine layers of information to give the user a better
understanding about that location. By using a Geographical Information System containing
geospatial data, one can develop useful scenarios to reduce natural disaster risk and vulnerability of
structures. In this paper, we describe a way of applying data mining techniques from the artificial
intelligence field to earthquake analysis in order to make a better investigation of the available data.
These methods are capable of finding “hidden” correlations among different subsets of data, which
cannot be revealed by means of simple statistics.
A Novel Prediction Technique for Interfacial Crack Growth of Electronic Interconnect
Authors: Lee Chang Chun , Ku Hsiao Tung , Chiu Chien Chia , Chiang Kuo Ning
Published: March 2009

The predicted fatigue life of packaging structures using conventional procedures of finite
element analysis (FEA) would be higher than an actual condition as a result of the perfect bonding
interface assumed in the modeling. Actually, the crack extension of the solder joints along with the
bi-material interface during the thermal cycling test had been observed. And, the crack models with
an assumed crack length had widely adopted which only responded to the stress distribution at that
moment instead of considering the effect of the whole stress history on the crack advancement. For
this reason, a node tie-release crack prediction technique integrated with a nonlinear FEA was
established in this research to further estimation for the thermo-mechanical reliability of solder
joints. To proof our proposed technique, a double-layer wafer level chip-scaling package (DLWLCSP)
was implemented as a testing vehicle to demonstrate the difference between the solder
joint reliability, which was compared to the application of conventional FEA. Combined with the
fracture criterion, the predicted result of using the present technique shown a lower fatigue life of
solder joints than another, which using conventional one when the phenomenon of crack growth in
dummy solder joints were considered. Finally, the actual experimental test showed the similar
results as presented tie-release crack prediction analysis.
Coupled THM Processes Modeling and Stochastic Simulation Considering Spatial Variability of Hydraulic Conductivity in Underground Storage Caverns
Authors: Zhang Cheng Yuan , Liu Xiao Yan , Liu Quan Sheng
Published: March 2009

Stochastic simulation method considering the heterogeneity of hydraulic conductivity is
suggested in this paper. Hydraulic field is simulated by using our FEM code for THM coupling
processes. The results show that hydraulic gradient at different location around the cavern is
differently dependent on water-curtain pressure in deterministic model. A probability range of
hydraulic gradient at each point with 10m space between each was examined by means of stochastic
realization of spacial variability of hydraulic conductivity. These analyses are contributed to
determine the values interval of water-pressure and groundwater flux into the cavern with a given
security for LPG containment design and evaluation considering the spacial variability of hydraulic
conductivity.
Application of Integrated Design System Based on Multi-Agent to Assess Cumulative Fatigue Damage of Large Scaled Welded Structure
Authors: Han Seung Ho , Bang Je Sung , Lee Jai Kyung , Song See Yeob
Published: March 2009

For the fatigue design of a large scaled welded structure, the readily accessibility of
various engineering tools is required for the static, fatigue, dynamic analysis and parametric study.
In this paper, a multi-agent system is suggested for the development of distributed, open and
intelligent design system. The developed design system is applied to assess cumulative fatigue
damage on the welded bogie frame of railway vehicles. The engineering tools for fatigue durability
analysis are chosen as I-DEAS, ANSYS and BFAP, in which iterative analysis is performed
automatically caused by geometrical changes of transom support bracket attached in the bogie
frame. The prototype of design system is implemented successfully for the assessment of
cumulative fatigue damages of the welded bogie frame.
Experimental Study on Frictional Force and Wear Life of Oilless Sintered-Metal Bearings for the Reliability of the Geared Motor
Authors: Oh Se Doo , Shin Yun Ha , Lee Young Ze
Published: March 2009

Oilless bearings, which are made with metal powders and then impregnated by oils, are
widely used in rotating components. The friction coefficients and the oil loss rates of two types of
oil-impregnated sintered-metal bearings (porous bearings, oilless bearings, or oilless metals) with
varying loads were measured. One is the Cu-based bearing and the other is Fe-based bearing. The
frictional forces of the bearings were measured using the journal bearing tester. By measuring the
change of weight before and after sliding tests, the oil losses of oilless bearings were surveyed. Also,
PV curves, which could be used to predict the life of the oilless bearing, were plotted. By observing
the roundness, the cylindericity and the images of scanning electron microscopy of bearings before
and after sliding tests, the tribological characteristics of the bearings were evaluated. It was found that
Fe-based bearing show lower friction, more oil flow, less wear and longer life than Cu-based bearing.
A Study on the Surface Treatments of the Barrel of Small Arms under the Firing Condition
Authors: Chae Je Wook , Lee Sung Bae , Lee Chan , Kim Hyun Jun , Lee Young Shin
Published: March 2009

This paper includes a study on the surface treatments of the barrel of small arms with an
aim at improving resistance of corrosion and wear. The inner surface of the barrel is Cr plated or
nitrided to improve the performance under the firing. The endurance test was conducted to compare
the wear resistance of standard barrel (the non surface treatment barrel), the Cr plating barrel and
the nitriding barrel. The wear resistance is evaluated by inner diameter of the barrel, muzzle
velocity and dispersion during the firing. And the salt water immersion test was conducted to
estimate the corrosion resistance. As the results of the tests, the Cr plating barrel is superior to the
NST barrel and the nitriding barrel in a view of corrosion and wear.
Characterization of Creep Resistance for Local Structure of Power Plant Weldment Using SP-Creep Technique
Authors: Baek Seung Se , Kwon Il Hyun , Lee Dong Whan , Yang Sung Mo , Yu Hyo Sun
Published: March 2009

Power plant weldments are composed of various microstructures. Due to welding and
PWHT processes, the microstructure of the base metal adjacent to fusion line is transformed into
entirely different microstructures, collectively known as heat affected zone (HAZ). Creep, on the
other hand, is considered as the most important deterioration mechanism of heat resistant
components found in power plants. Therefore it is essential to evaluate creep properties of HAZ,
which is considered to be very hazardous in weldment. Recently, most of the creep tests for HAZ
are conducted using cross weld type specimen. However there are some problems with this type of
creep test due to the results being largely varied according to the volume fraction of HAZ. In this
paper, SP-Creep test, which has confirmed the availability for creep properties evaluation, has been
conducted on each of the weldment microstructures. The results showed that each microstructure
has a different creep behavior. The overall creep properties of HAZ are worse than those of the
weld metal. Among the HAZ structures, fine grained HAZ has the worst creep properties.
Characterization of the Fracture Process of a Plate-Type Piezoelectric Composite Actuator under a Bending Load by Acoustic Emission Monitoring
Authors: Woo Sung Choong , Goo Nam Seo
Published: March 2009

Characteristics during the fracture process of a plate-type piezoelectric composite
actuator (PCA) using acoustic emission (AE) monitoring were investigated under a bending load.
The fracturing of a monolithic PZT ceramic shows typically brittle behavior; furthermore, the AE
signal at the maximum load, which corresponds to the final fracture, has a high amplitude and long
duration. Analysis of dominant frequency bands by a fast Fourier transform (FFT) in conjunction
with AE parametric analysis expressed the characteristic changes of the fracture process in the PCA.
For the PCA, a brittle fracture in a PZT ceramic layer induces the local delamination between the
PZT ceramic and adjacent fiber composite layers. Based on the AE analysis and damage
observations through optical microscopy, the features of AE associated with fracture process can be
elucidated for the PCA.
Nondestructive Evaluation of CVD Diamond Coating Layers Using the Leaky Rayleigh Surface Wave
Authors: Wang Wen Wu , Song Sung Jin , Kim Hak Joon , Yang Dong Ju , Kwon Sung Duk
Published: March 2009

Chemical vapor deposit (CVD) diamond coating layer is expected to extend the lifetime of
mechanical parts that are used severely abrasive conditions. However, one of the most severe
problems is that the delamination between the CVD diamond coating layer and the silicon substrate
occurs frequently due to large difference in the material properties. Therefore, the nondestructive
evaluation of adhesive property of CVD diamond coating layer is needed. To address such a need,
back-scattered Rayleigh surface wave is currently applied. However, the interpretation of the acquired
signal is not easy at all. To take care of such a difficulty, we proposed the time trace angular scan
(TTAS) plot and the frequency spectrum angular scan (FSAS) plot that can make possible of the
systematic interpretation of the back-scattered signals from the diamond coating layer. In this paper,
the concept of the TTAS and FSAS plots and the experimental results presented to demonstrate the
effectiveness of the proposed approach.
Novel Silk Scaffolds for Ligament Tissue Engineering Applications
Authors: Toh S.L. , Teh T.K.H. , Vallaya S. , Goh J.C.H.
Published: March 2009

Scaffold technology is integral in advancing tissue engineering and one of the tissues of
interest here is the tendon/ligament. Advancement in the tissue engineering of tendon/ligament has
become very much a materials engineering problem than ever, with the selection of appropriate
biomaterial and scaffold architecture. Such is the key to successful tendon/ligament tissue
regeneration construct. Popular materials used in recent years include various poly (l-lactic)
biomaterials and collagen. However, shortcomings of these materials, in terms of poor mechanical
strength or short degradation period, are yet overcome. Bombyx mori silk, though used in
biomedical sutures for decades due to its excellent mechanical properties, has been overlooked for
applications in ligament tissue engineering, only until recently. This is largely due to previous
misconceptions in its biocompatibility and biodegradability characteristics. This paper describes the
use of a silk-based scaffold with knitted architecture and investigates its strengths as compared to
previous PLGA-based knitted scaffolds. An electrospun nanofiber surface on knitted microfiber
architecture is adopted and it is found to have better composite-material integrity, in vitro
degradation resistance, and encourages cell adhesion and proliferation.
Analysis of Body Pressure Distributions of the Air-Cell Mattress for Preventing Decubitus Ulcer
Authors: Cho Hyeon Seok , Ryu Jei Chung , Kim Gyoo Suk , Mun Mu Sung , Kim Kyung Hoon , Lee In Hyuk
Published: March 2009

A finite element simulation model was developed for the performance optimization of a
closed type air-cell mattress used for the ulcer prevention. An H-model with material properties of
human flesh and kinematic joints were used for the calculation of the body contact pressure. The
material property of rubber air-cell was evaluated by tensile test of standard specimen. We
evaluated the body contact pressure distribution after laying human model on the inflated air-cell
mattress. It was found that the body contact pressure was dependent on cell height, but hardly
affected by the cell thickness.
Characterization of the Biomechanical Properties of the Lower Esophagus for Surgical Simulation
Authors: Choi Chang Mok , Han Hyon Yung , Kim Jung , Cheong Joo No
Published: March 2009

In this work a method to characterize soft tissue properties for mechanical modeling is
presented. Attention is especially focused on developing a model of the lower esophagus to be used
in a surgical simulation, which shows a promise as a training method for medical personnel. The
viscoelastic properties of the lower esophageal junction are characterized using data from animal
experiments and an inverse FE parameter estimation algorithm. Utilizing the assumptions of quasilinear-
viscoelastic theory, the viscoelastic and hyperelastic material parameters are estimated to
provide a physically based simulation of tissue deformations in real time. To calibrate the
parameters to the experimental results, a three dimensional FE model that simulates the forces at the
indenter and an optimization program that updates new parameters and runs the simulation
iteratively are developed. It was possible to reduce the time and computation resources by
decoupling the viscoelastic part and elastic part in a tissue model. The comparison of the simulation
and the experimental behavior of pig esophagus are presented to provide validity to the tissue model
using the proposed approach.
Electric Signal Detection of a Microfilter-Based Biochip for Immunoassay Using Microbead, Nanogold Particle, and Silver Enhancement
Authors: Ko Yong Jun , Cho Chul Ho , Maeng Joon Ho , Lee Byung Chul , Ahn Yoo Min , Cho Nahm Gyoo , Lee Seoung Hwan , Hwang Seung Yong
Published: March 2009

This paper presents a microbiochip which can detect an antigen-antibody reaction
through an electrical signal in real time with high sensitivity and low sample volume by using
nanogold particle and silver enhancement. A filtration method using the microbead is adopted for
sample immobilization. The chip is composed of an inexpensive and biocompatible
Polydimethylsiloxane (PDMS) layer and Pyrex glass substrate. Platinum microelectrodes for
electric signal detection were fabricated on the substrate and microchannel and pillar-type
microfilters were formed in the PDMS layer. Successively introducing polystyrene microbeads
precoated with protein A, anti-protein A (which was the first antibody) and the second antibody
conjugated with nanogold particles into the microchannel, the resulting antigen-antibody complex
was fixed on the bead surface. The injection of silver enhancer increased the size of nanogold
particles tagged with the second antibody. As a result, microbeads were connected to each other and
formed an electrical bridge between microelectrodes. Resistance measured through the electrodes
showed a difference of two orders of magnitude between specific and nonspecific immunoreactions.
The developed immunoassay chip reduced the time necessary for an antigen-antibody
reaction to 10 min, thus shortening the overall analysis time from 3 hours to 50 min. The
immunoassay chip reduces analysis time for clinical diagnoses, is simple, and has high sensitivity.
Plastic Ankle Foot Orthosis for Hemiplegics and Structural Analysis
Authors: Lee Young Shin , Choi Kyung Joo , Cho Kang Hee , Choi Young Jin , Lim Hyun Kyoon , Kim Bong Ok
Published: March 2009

AFO is a device, which is usually recommended for hemiplegics to help their pathologic
gait. To date, no good engineering guidance is available. We analyze mechanical characteristics of
AFO and evaluate structural stability effect of thickness of ankle foot orthosis (AFO). The study is
to provide a guidance to make a functional AFO. Basic material characteristics such as Young’s
modulus and Possion’s ratio were measured through material tests. Finite element models were
made and analyzed based on various shapes and gait analysis. Young’s modulus of polypropylene is
1.15 GPa and Possion’s ratio is 0.35. Rigidity of AFO is more affected by the ankle width than the
thickness of ankle area. The strain calculated by finite element analysis (FEA) in the neck area is
twice as much as experimental results but the both of their trend show similar pattern. AFO was
studied through its structural and functional analysis. Experimental structural analysis and FEA
were made and compared.
Characterization of Multipoint Diffraction Strain Sensor (MISS)
Authors: Iqbal S. , Asundi Anand Krishna
Published: March 2009

A Multipoint Diffraction Strain Sensor (MISS) with the novel feature of simultaneous
strain measurement at multiple points is characterized. Unlike conventional interferometry based
systems, this patented sensor uses principles of diffraction to directly measure strain at large
number of points. In this sensor, a high-frequency diffraction grating is illuminated by two
symmetric laser beams and the diffracted beams are sampled on a CCD camera via a micro-lens
array into an array of dots. The shift of the individual dots is sensed and strains or rigid body tilt are
calculated directly. This novel technique is expected to be very valuable in numerous industrial
applications.
The Effects of Muscle Forces on Ankle Joint Kinetics during Postural Balance Control
Authors: Choi Hyeon Ki , Seo Min Jwa , Koo Ja Choon , Choi Hyeon Chang , Cho Won Hak
Published: March 2009

We assessed the effects of muscle forces on ankle joint kinetics during postural balance
control of human boy. Nine male subjects (mean age of 25.8 yrs) participated in the experiment. An
ankle joint model assumed ball and socket joint was used, which was capable of three dimensional
rotations. A six-camera VICON system was used for motion analysis. Waist pulling system and
force platform were adopted for forward sway and GRF (ground reaction force) measurement. We
used linear optimization programs to calculate the variation of muscle forces and angular
displacements of shank and foot segments. With the experimental data and linear programs, we
could calculate joint reaction forces, and bone-on-bone forces. The results presented in this study
give us the insights to understand the roles of lower limb muscles during postural balance control
and ankle injury mechanism.
Medical Image Analysis by Robot Kinematics
Authors: An Jae Bum , Xin Li Li
Published: March 2009

In this paper we present an analysis of medical images based on robot kinematics. One of
the most important problems in robot-assisted surgeries is associated with the medical image
registration of surgical tools and anatomical targets. The fundamental problems of contemporary
frame-based image registration are that the registration fails in case of incomplete data in the image
and the registration algorithm depends on the shape, assembly, and number of fiducials. To solve
the registration problem in the situation where a cylindrical end-effector of surgical robots operates
inside the patient’s body, we developed a numerical method by applying robot kinematics
knowledge to cross-sectional medical images. Our method includes a 6-D registration algorithm and
a cylindrical frame with four helix and one straight line fiducials. The numerical algorithm requires
only a single cross-sectional image and are robust to noise and missing data, and are algorithmically
invariant to the actual shape, number, and assembly of fiducials. The algorithm and frame are
introduced in this paper, and simulation results are described to show the adequate accuracy and
resistance to noise.
Development of Model Cell Based on the Myocardial Cell Experiments and Simulations
Authors: Tang T. , Wang S.Q. , Zhuang Zhuo
Published: March 2009

As one kind of the most important cells in human body, myocardial cell becomes the focus of
attention, not only the biologist but also the researchers of mechanics. A new viscoelastic
constitutive model of the living myocardial cell is developed based on the micropipette suction
experiment in which the surface of the cell is aspirated into a small glass tube while tracking the
leading edge of its surface. Some numerical simulations are presented by finite element to model
the whole process of micropipette suction of the myocardial cell. Meanwhile, a model cell with both
mechanical behavior and physiological function is being developed, to prove the viscoelastic
constitutive model and to predict more results of myocardial cell under different physiology
conditions.
Temperature Dependence of Threshold Stress Intensity Factor, KIH in Zr-2.5Nb Alloy and Its Effect on Temperature Limit for Delayed Hydride Cracking
Authors: Kim Young Suk , Ahn Sang Bok , Kim Kang Soo , Cheong Yong Moo
Published: March 2009

Threshold stress intensity factor or KIH required to initiate a delayed hydride crack in the
axial direction of a Zr-2.5Nb tube was determined at temperatures of 160 oC to 280 oC. KIH
remained constant at temperatures from 160 to 250 oC, increased with an increasing temperature in
excess of 280 oC using a load decreasing method. To correlate KIH and dislocation twins, tensile
tests were conducted on the Zr-2.5Nb tube and textural changes during tensile tests were
investigated using an X-ray diffractometer. The extent of the twins increased from 150 to 300 oC
and then decreased at temperatures in excess of 300 oC with no twins occurring at 350 oC.
Temperature dependencies of KIH and a temperature limit for delayed hydride cracking were
discussed with cracking of hydrides by the twins. This study provides supportive evidence to the
feasibility of Kim’s DHC model.
Constraint of Semi-Elliptical Surface Cracks in T and L-Joints
Authors: Lee Hyung Yil , Kim Yun Jae
Published: March 2009

Critical defects in pressure vessels and pipes are generally found in the form of a semielliptical
surface crack, and the analysis of which is consequently an important issue in engineering
fracture mechanics. Furthermore, in addition to the traditional single parameter K or J-integral, the
second parameter like T-stress should be measured to quantify the constraint effect. In this work,
the validity of the line-spring model is investigated by comparing line-spring J-T solutions to the
reference 3D finite element J-T solutions. A full 3D-mesh generating program for semi-elliptical
surface cracks is employed to provide such reference 3D solutions. Then some structural
characteristics of the surface-cracked T and L-joints are studied by mixed mode line-spring finite
element. Negative T-stresses observed in T and L-joints indicate the necessity of J-T two parameter
approach for analyses of surface-cracked T and L-joints.
Optimization on the Spot Welded Configuration of Vehicle Components Considering the Structural Performance
Authors: Eom J.S. , Ju B.H. , Choi N. , Park J.M. , Lee Byung Chai , Byun H.B.
Published: March 2009

In the motor industry, the number of spot welded points is closely related to overall cost
of the vehicle assembly. A design based on experience is probable to lead redundant spot welded
joints. Welded joints are critical in the structural performance, so it is hard to reduce the number.
A measurable design index on the design of spot weld configuration is proposed in this study. We
optimized the spot welding location and number in the lower control arm of the vehicle and
automobile body, as far as the structure retained the structural stiffness. In order to ensure the
requirements, we use a sizing optimization of each spot weld stiffness for the global structural
rigidity. The survival index is defined the summation of resulted design variables, which is equal to
the number of survival in the series of sizing optimizations. With this design index, one can
optimally measure the importance of each spot weld joint and remove the redundant spot welds
from the structure design.
Fatigue Fracture Behavior of Mg-Zn-Y Alloy
Authors: Ando Shinji , Toda Kazuaki , Tsushida Masayuki , Tonda Hideki , Kawamura Yoshihito
Published: March 2009

Recently, Mg-Zn-Y alloys with superior performance, which have a long period order
(LPO) phase, have been developed. Therefore, it is important to understand fundamental fatigue
properties in such materials. In this study, the fatigue fracture behavior of Mg-Zn2-Y2-Zr0.2 alloy has
been investigated using a plain fatigue bending testing machine, which was originally developed for
thin sheet specimen. One end of the sheet specimen is fixed at a voice coil of the loudspeaker and
the other end is set free. A bending mode resonance occurs in the specimen due to forced vibration
at the fixed end. To estimate stress amplitude of bending, deflections at the free end of the specimen
oscillating at a frequency of about 250~700Hz was measured by a laser displacement gauge. For
comparison, AZ31B alloy also has been investigated. S-N curve for the Mg-Zn2-Y2-Zr0.2 alloy
was obtained using a stress ratio of R=-1, and the fatigue strength was estimated as about 200MPa
at 106~108 cycles. The value corresponds to about 50% of 0.2% proof strength of the alloy. Two
types of fatigue surface were observed in the alloy. One is striation like pattern and the other is
relatively flat surface. The former is similar to fatigue surface of AZ31B. Therefore, these two types
of fatigue surface correspond to crack passing through α-Mg phase and LPO phase, respectively.
Digital Speckle Projection for Vibration Measurement by Applying Digital Image Correlation Method
Authors: Yang Fu Jun , He Xiao Yuan
Published: March 2009

Digital image correlation method (DICM) is described as a robust in-plane deformation
measuring method due to its simple optical setup and the insensitivity against ambient noise. Based
on DICM, digital speckle projection has been developed for shape measurement. This paper
explores the possibilities for vibration analysis using digital speckle projection together with DICM.
A digital speckle pattern, generated by computer, is projected on an object surface using an LCD
projector. Then the dynamic deformation modulated speckle images are captured by a high-speed
CCD camera and saved in the computer. By using the self-developed temporal sequence digital
images correlation algorithm, the deformation and vibration mode can be analyzed quantitatively.
The proposed method avoids using stroboscopic or laser illumination and simplifies the
experimental setup for vibration measurement, while it is time-consuming thanks to calculating a
large amount of correlation coefficients. The experimental performance on a harmonic-vibrating
cantilever beam well demonstrates the validity of the new method.