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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 32, Issue 12 - Dec 2008
Volume 32, Issue 11 - Nov 2008
Volume 32, Issue 10 - Oct 2008
Volume 32, Issue 9 - Sep 2008
Volume 32, Issue 8 - Aug 2008
Volume 32, Issue 7 - Jul 2008
Volume 32, Issue 6 - Jun 2008
Volume 32, Issue 5 - May 2008
Volume 32, Issue 4 - Apr 2008
Volume 32, Issue 3 - Mar 2008
Volume 32, Issue 2 - Feb 2008
Volume 32, Issue 1 - Jan 2008
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An Electrical Particle Velocity Profiler Using Particle Transit Time Across Uneven Inter-Gap Electrodes
Kim, Tae-Yoon ; Lee, Dong-Woo ; Cho, Young-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 297~302
DOI : 10.3795/KSME-A.2008.32.4.297
We present an electrical particle velocity profiler using particle transit time across uneven inter-gap electrodes. We measure both the particle position and velocity from the voltage signals generated by the particles passing across sensing electrodes, thus obtaining the velocity profile of the particles in a microfluidic channel. In the experimental study, we use polystyrene microparticles to characterize the performance of the electrical particle velocity profiler. The particle velocity profile is measured with the uncertainty of 5.44%, which is equivalent to the uncertainty of 5% in the previous optical method. We also experimentally demonstrate the capability of the present method for in-channel clogging detection. Compared to the previous optical methods, the present electrical particle velocity profiler offers the simpler structure, the cheaper cost, and the higher integrability to micro-biofluidic systems.
Investigation into Deformation of Three-Dimensional Microstructures via Surface Tension of a Rinsing Material During a Developing Process
Park, Sang-Hu ; Yang, Dong-Yol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 303~309
DOI : 10.3795/KSME-A.2008.32.4.303
Dense and fine polymer patterns often collapse, as they come into contact with each other at their protruding tips. Resist pattern collapse depends on the aspect ratio of patterns and the surface tension of rinsing materials. The pattern collapse is a very serious problem in microfabrication, because it is one of the factors which limit the device dimensions. The reasons for the pattern collapse are known as the surface tension of rinse liquid, centrifugal force and rinse liquid flow produced in the developing process. In this work, we tried to evaluate the pattern collapse of three-dimensional microstructures that were fabricated by two-photon induced photopolymerization, and showed the way how to reduce the deformation of microstructures.
Design of Parallel Typed Walking Robot for Improvement of Walking Space and Stability
Kim, Chi-Hyo ; Park, Kun-Woo ; Kim, Tae-Sung ; Lee, Min-Ki ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 310~318
DOI : 10.3795/KSME-A.2008.32.4.310
This paper presents a parallel typed walking robot to improve walking space and stability region. The robot is designed by inserting an intermediate mechanism between upper leg mechanism and lower leg mechanism. The leg mechanism is composed of three legs and base, which form a parallel mechanism with ground. Seven different types of walking robot are invented by combining the leg mechanisms and an intermediate mechanism. Topology is applied to design the leg mechanism. A motor vector is adopted to determine Jacobian and a wrench vector is used to analyze dynamics of the robot. We explore the stability region of the robot from the reaction force of legs and compute ZMP including the holding force to contact the foot to a wall. This investigates a walking stability when the robot walks on the ground as well as on the wall. We examine the walking space generated by support legs and by swing legs. The robot has both a large positional walking space and a large orientational walking space so that it can climb from a floor up to a wall.
Study on the Void Growth and Coalescence in F.C.C. Single Crystals
Ha, Sang-Yul ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 319~326
DOI : 10.3795/KSME-A.2008.32.4.319
In this study, we investigate the deformation behavior of F.C.C. single crystals containing micro- or submicron-sized voids by using three dimensional finite element methods. The locally homogeneous constitutive model for the rate-dependent crystal plasticity is integrated based on the backward Euler method and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). The unit cell analysis has been investigated to study the effect of stress triaxiality and crystallographic orientations on the growth and coalescence of voids in F.C.C. single crystals.
Process Development of Variable Curvature Extrusion for Automotive Aluminum Bumper
Kim, Byung-Min ; Jo, Young-June ; Oh, Kae-Hee ; Park, Sang-Woo ; Lee, Sang-Kon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 327~332
DOI : 10.3795/KSME-A.2008.32.4.327
The effectiveness of vehicle parts made through extrusion is in the limelight because of the advantages of high strength stiffness materials can be produced and the number of processes can be drastically reduced. Therefore, the parts should have sufficient stiffness and be lightweight enough to improve fuel efficiency. However, the application of extruded aluminum requires pre-bending technologies that can manufacture the complex designs profiles demanded by vehicle parts. The aim of this research is that the development of the variable curvature extrusion technology that can produce a variety of curvature. In order to produce a variable curvature, the guide transfer speed and transfer time should be controlled properly. The guide transfer speed and transfer time were examined by the theoretical analysis. A model was developed to simulate the deformation behaviors of extrusion and bending process from the symmetric bumper with range of radii from 1863mm to 2163mm. The theoretical analysis and FE analysis were verified through experimental method.
The Effect of an Aluminum Mold on Densification of Copper Powder Under Warm Pressing
Lee, Sung-Chul ; Park, Tae-Uk ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 333~339
DOI : 10.3795/KSME-A.2008.32.4.333
Densification behavior of copper powder was investigated to study the effect of an aluminum mold under warm pressing. The low flow stress of an aluminum mold is appropriate to apply hydrostatic stress to powder compacts during compaction under high temperature. The suggested powder metallurgy process is very useful under high temperature since copper powder compacts have higher relative density over axial stress of 100 MPa and show more homogeneity as compared with conventional warm pressing. Elastoplastic constitutive equation proposed by Shima and Oyane was implemented into a finite element program (ABAQUS) for densification behavior under warn pressing by using a metal mold. Finite element results agreed well with experimental data for densification and deformation of copper powder compacts in the mold.
Simulation Based Design of Intelligent Surveillance Robot for Mobility
Hwang, Ki-Sang ; Kim, Do-Hyun ; Park, Kyu-Jin ; Park, Sung-Ho ; Kim, Sung-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 340~346
DOI : 10.3795/KSME-A.2008.32.4.340
An unmanned surveillance robot consists of a machine gun, a laser receiver, a thermal imager, a color CCD camera, and a laser illuminator. It has two axis control systems for elevation and azimuth. Because the current robot system is mounded at a fixed post to take care of surveillance tasks, it is necessary to modify such a surveillance robot to be installed on an UGV (Unmanned Ground Vehicle) system in order to watch blind areas. Thus, it is required to have a stabilization system to compensate the disturbance from the UGV. In this paper, a simulation based design scheme has been adopted to develop a mobile surveillance robot. The 3D CAD geometry model has first been produced by using Pro-Engineer. The required pan and tilt motor capacities have been analyzed using ADAMS inverse dynamics analysis. A target tracking and stabilization control algorithm of the mobile surveillance robot has been developed in order to compensate the motion of the vehicle which will experience the rough terrain. To test the performance of the stabilization control system of the robot, ADAMS/simulink co-simulations has been carried out.
Study on Algorithm of Micro Surface Roughness Measurement Using Laser Reflectance Light
Choi, Gyu-Jong ; Kim, Hwa-Young ; Ahn, Jung-Hwan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 347~353
DOI : 10.3795/KSME-A.2008.32.4.347
Reflected light can be decomposed into specular and diffuse components according to the light reflectance theory and experiments. The specular component appears in smooth surfaces mainly, while the diffuse one is visible in rough surfaces mostly. Therefore, each component can be used in forming their correlations to a surface roughness. However, they cannot represent the whole surface roughness seamlessly, because each formulation is merely validated in their available surface roughness regions. To solve this problem, new approaches to properly blend two light components in all regions are proposed in this paper. First is the weighting function method that a blending zone and rate can be flexibly adjusted, and second is the neural network method based on the learning from the measurement data. Simulations based on the light reflectance theory were conducted to examine its performance, and then experiments conducted to prove the enhancement of the measurement accuracy and reliability through the whole surface roughness regions.
The Evaluation of Surface and Adhesive Bonding Properties for Cold Rolled Steel Sheet for Automotive Treated by Ar/O
Atmospheric Pressure Plasma
Lee, Chan-Joo ; Lee, Sang-Kon ; Park, Geun-Hwan ; Kim, Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 354~361
DOI : 10.3795/KSME-A.2008.32.4.354
Cold rolled steel sheet for automotive was treated by Ar/
atmospheric pressure plasma to improve the adhesive bonding strength. Through the contact angle test and calculation of surface free energy for cold rolled steel sheet, the changes of surface properties were investigated before and after plasma treatment. The contact angle was decreased and surface free energy was increased after plasma treatment. And the change of surface roughness and morphology were observed by AFM(Atomic Force Microscope). The surface roughness of steel sheet was slightly changed. Based on Taguchi method, single lap shear test was performed to investigate the effect of experimental parameter such as plasma power, treatment time and flow rate of
gas. Results shows that the bonding strength of steel sheet treated in Ar/
atmospheric pressure plasma was improved about 20% compared with untreated sheet.
A 2D FE Model for Unique Solution of Peening Residual Stress in Single Shot Impact
Kim, Tae-Hyung ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 362~370
DOI : 10.3795/KSME-A.2008.32.4.362
In this paper, we propose a 2D-FE model in single impact with combined physical factors to obtain a unique residual stress by shot peening. Applied physical parameters consist of elastic-plastic deformation of shot ball, material damping coefficients, strain rate, dynamic friction coefficients. As a kinematical parameter, there is impact velocity. Single impact FE model consists of 2D axisymmetric elements. The FE model with combined factors showed converged and unique distributions of surface stress, maximum compressive residual stress and deformation depth. Further, in contrast to the FE models with rigid shot and elastic deformable shot, FE model with plastic deformable shot produces residual stresses very close to experimental solutions by X-ray diffraction. We therefore validated the 2D FE model with combined peening factors and plastic deformable shot. This FE model will be a base of the 3D FE model for residual stresses by multi-impact shot peening.
Development of Detachable PDMS/Glass PCR-Chip and It`s Application to Detection of Male Infertility
Ju, Jin-Kyoung ; Hwang, Seung-Young ; Ahn, Yoo-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 4, 2008, Pages 371~377
DOI : 10.3795/KSME-A.2008.32.4.371
Our precedent study has reported glass-PDMS (polydimethylsiloxane) based biochip for the gene PCR (polymerase chain reaction). To prevent the contamination of bio sample, the once used biochip must not be used repeatedly. However, the fabrication cost of microheater and microsensor of the biochip was not cheap to use it as a disposable chip. This paper proposes new PCR-chip where the glass substrate integrated with the microheater and microsensor is detachable from the reaction chamber where the sample is injected. That makes it possible to reuse the glass substrate repeatedly. The performance of the proposed detachable PCR-chip was compared with that of the precedent monolithic PCR-chip. The results showed that the SRY (sex determining Y chromosome) gene PCR was successfully performed in the detachable chip compared with the monolithic chip. However, the more efforts to improve the efficiency of surface treatment of PDMS chip are needed to increase the possibility of applying the detachable chip to the detecting of male infertility.