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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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Densification Behavior of Dissimilar Material Powder during Die Compaction
Kim, Taek-Eui ; Lee, Sung-Chul ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 379~386
DOI : 10.3795/KSME-A.2008.32.5.379
Densification behavior of dissimilar material powder (copper and pure iron powder) under die compaction was investigated. Experimental data were obtained for copper and pure iron powder compacts with various volume ratios under die compaction. Dissimilar material powder was simultaneously compacted into a jointed cylindrical compact with different powder materials in inner and outer part, respectively. To simulate densification behavior of dissimilar material powder, elastoplastic constitutive equation proposed by Shima and Oyane was implemented into a finite element program (ABAQUS) under die compaction. Finite element results were compared with experimental data for densification, deformed geometry and density distribution of powder compacts under die compaction.
Deformation of the Rubber Mold by Using the Cohesive Zone Model Under Cold Isostatic Pressing
Lee, Sung-Chul ; Kim, Ki-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 387~395
DOI : 10.3795/KSME-A.2008.32.5.387
Stress distribution and interfacial debonding process at the interface between a rubber mold and a powder compact were analyzed during unloading under cold isostatic pressing. The Cap model proposed by Lee and Kim was used for densification behavior of powder based on the parameters involved in the yield function of general Cap model and volumetric strain evolution. Cohesive elements incorporating a bilinear cohesive zone model were also used to simulate interfacial debonding process. The Cap model and the cohesive zone model were implemented into a finite element program (ABAQUS). Densification behavior of powder was investigated under various interface conditions between a rubber mold and a powder compact during loading. The residual tensile stress at the interface was investigated for rubber molds with various elastic moduli under perfect bonding condition. The variations of the elastic energy density of a rubber mold and the maximum principal stress of a powder compact were calculated for several interfacial strengths at the interface during unloading.
Continuous Scanning Method for Improvement of Precision and Fabrication Efficiency of Two-Photon Stereolithography
Lim, Tae-Woo ; Son, Yong ; Yang, Dong-Yol ; Kong, Hong-Jin ; Lee, Kwang-Sup ; Park, Sang-Hu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 396~401
DOI : 10.3795/KSME-A.2008.32.5.396
Minimization of processing time in two-photon stereolithography (TPS) has been one of important issues. Generally, a voxel scanning method (VSM) has been used in TPS because the method is very profitable for the stable fabrication irrespective of jittering and response time of scanning equipments such as a stage and a galvano-scanner. However, supplementary processing time due to the on/off control of a shutter for the generation of each voxel is required inevitably in VSM; by this reason, much processing time takes to fabricate largescale micropatterns and three-dimensional patterns. In this work, a continuous scanning method (CSM), generating patterns by movement of beam focus with a constant speed, is proposed for the improvements of scanning speed and precision in TPS. Some line patterns are fabricated by each scanning method to demonstrate the usefulness of CSM with viewpoints of scanning speed and precision.
Structural Analysis on the Heavy Duty Diesel Engine and Optimization for Bearing Cap
Lee, Jae-Ok ; Lee, Young-Shin ; Lee, Hyun-Seung ; Kim, Jae-Hoon ; Jun, Joon-Tak ; Kim, Chul-Goo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 402~410
DOI : 10.3795/KSME-A.2008.32.5.402
The heavy duty diesel engine must have a large output for maintaining excellent mobility. In this study, a three dimensional finite element model of a heavy-duty diesel engine was developed to conduct the stress analysis. The FE model of the heavy duty diesel engine main parts consisting with four half cylinder was selected. The heavy duty diesel engine parts includes with cylinder block, cylinder head, gasket, liner, bearing cap, bearing and bolts. The loading conditions of engine were pre-fit load, assembly load, and gas load. As the results of structural analysis, because the stress values of cylinder block and bearing cap did not exceed the basic design can be satisfied. But on the part which contacts with cylinder block and bearing cap the stress value exceeds the allowable strength of material. In order to decrease the stress at that part, it was optimized with parametric study.
Mis-Match Limit Load Analyses and Approximate J-Integral Estimates for Similar Metal Weld with Weld-Center Crack Under Tension Load
Song, Tae-Kwang ; Kim, Yun-Jae ; Kim, Jong-Sung ; Jin, Tae-Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 411~418
DOI : 10.3795/KSME-A.2008.32.5.411
In this work, the effect of strength mismatch on plastic limit loads is quantified for similar metal weld plates with cracks under tension load, via three-dimensional, small strain elastic-perfectly plastic finite element analyses. Relevant variables related to plate geometry and crack length are systematically varied, in addition to the weld width. An important finding is that mis-match limit loads can be uniquely quantified through strength mis-match ratio and one geometry-related parameter. Based on the proposed limit load solutions, reference stress based J-integral estimates is also investigated. When the reference stress is defined by the mis-match limit load, predicted J-integral values agree overall well with FE results.
Polymer Replication Using Ultrasonic Vibration
Yu, Hyun-Woo ; Lee, Chi-Hoon ; Ko, Jong-Soo ; Shin, Bo-Sung ; Rho, Chi-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 419~423
DOI : 10.3795/KSME-A.2008.32.5.419
A new polymer replication technology using ultrasonic vibration is proposed and demonstrated. A commercial ultrasonic welder has been used in this experiment. Two different types of nickel molds have been fabricated: pillar type and pore type microstructures. Polymethyl methacrlylate (PMMA) has been used as the replication material and the optimal molding time was 2 sec and 2.5 sec for pillar-type and pore-type micromolds, respectively. Compared with the conventional polymer micromolding techniques, the proposed ultrasonic micromolding technique has the shortest processing time. In addition, only contact area between micromold and polymer substrate is melted so that the thermal shrinkage can be minimized. The fabricated PMMA microstructures have been very accurately replicated without vacuum. The proposed ultrasonic molding technique is a good alternative for high volume production.
The Effect of Micro Nano Multi-Scale Structures on the Surface Wettability
Lee, Sang-Min ; Jung, Im-Deok ; Ko, Jong-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 424~429
DOI : 10.3795/KSME-A.2008.32.5.424
Surface wettability in terms of the size of the micro nano structures has been examined. To evaluate the influence of the nano structures on the contact angles, we fabricated two different kinds of structures: squarepillar-type microstructure with nano-protrusions and without nano-protrusions. Microstructure and nanostructure arrays were fabricated by deep reactive ion etching (DRIE) and reactive ion etching (RIE) processes, respectively. And plasma polymerized fluorocarbon (PPFC) was finally deposited onto the fabricated structures. Average value of the measured contact angles from microstructures with nanoprotrusions was
higher than that from microstructures without nano-protrusions. This result indicates that the nano-protrusions give a crucial effect to increase the contact angle.
Electrical Lifetime Estimation of a Relay by Accelerated Life Test
Kim, Jae-Jung ; Chang, Seog-Weon ; Son, Young-Kap ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 430~436
DOI : 10.3795/KSME-A.2008.32.5.430
This paper proposes a way to predict electrical lifetime of a relay using Accelerated Life Testings (ALTs). The relay of interest mounting on printed circuit boards is usually under an inrush current stress. The inrush current is generated and accelerated through controlling a lamp switching device in the ALT. We find that the dominant failure mechanism under high levels of inrush current would be contact welding in the contact surface of the relay and the contact welding process is accelerated according to increase in inrush current. The electrical lifetime model based on Inverse Power Law in term of inrush current is proposed, and parameters characterizing relay's lifetime distribution are statistically estimated using ALTA 6 PRO software.
Analysis and Control of the Flexible Multibody System Using MATLAB
Jung, Sung-Pil ; Park, Tae-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 437~443
DOI : 10.3795/KSME-A.2008.32.5.437
In this paper, analysis and control of the flexible multibody system using MATLAB is presented. The equations of motion of a flexible body are derived in terms of the modal coordinate. The rigid-flexible multibody dynamic solver is developed. Finite element information required to analyze motion of flexible bodies is imported from ANSYS. The modified finite element data, such as modal mass matrix, modal stiffness matrix and constraint mode shapes, is calculated in the solver. Since the solver is developed using MATLAB, it is very easy to connect with SIMULINK which is widely used to control motion of the multibody system. Several simulations are implemented to verify the developed solver. A control example is carried out and the usefulness of the developed solver is demonstrated.
The Simulation of Fatigue Fracture Effect of Arterial Wall on Blood Pressure
Shin, Sang-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 444~450
DOI : 10.3795/KSME-A.2008.32.5.444
The conventional studies of the aging effect on cardio-vascular system are mostly obtained from human experiences and can only provide local information. In this study, the effect of fatigue fracture of arterial wall on the blood pressure was investigated by hemodynamic analysis. The aging process was simulated with three stages. The pulse wave velocity increased with age. The systolic blood pressure increases consistently but diastolic blood pressure decreases with age. The simulated results show in good accordance with the clinical ones.
Flat Panel Display Deflection Analysis Considering Lift Force in Non-Contact Flat Panel Display Conveyer System
Hwang, Sung-Hyen ; Choi, Hyeon-Chang ; Lho, Te-Jung ; Son, Te-Yong ; Park, Bum-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 5, 2008, Pages 451~457
DOI : 10.3795/KSME-A.2008.32.5.451
Flat Panel Display(FPD) is widely used a video display terminals to consumer products of LCD and PDP. The contamination and damage were affected by using the previous contact conveyor's method. In this paper, it analyzes the FPD deflection to develop the non-contact FPD transfer process using lift force. Each conveyor's equipment is called a horizontal conveyor, vertical conveyor and robot pick-up equipment. As result of an analysis of FPD panel's deflection, a robot pick-up equipment has performed according to under the present conditions like panel's weight and loaded glass to move FPD panel from one place to other places properly. Results of the analysis showed 0.474 mm, 0.424 mm and 1.237 mm. Those values are lower than a predicted optimum values : 2 mm for both horizontal and vertical conveyers; 5 mm for robot pick-up equipment. Therefore, those results verify each equipment have safety and reliability.