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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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Analysis of Stress-Strain Relationship of Nano Structures According to the Size and Crystal Orientation by Using the Molecular Dynamics Simulation
Kang, Yong-Soo ; Kim, Hyun-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1047~1054
DOI : 10.3795/KSME-A.2008.32.12.1047
In this paper, the molecular dynamics (MD) simulations are performed with single-crystal copper blocks under simple shear and simple tension to investigate the effect of size and crystal orientation. There are many variances to give influences such as deformation path, temperature, specimen size and crystal orientation. Among them, the crystal orientation has a primary influence on the volume averaged stress. The numerical results show that the volume averaged shear stress decreases as the specimen size increases and as the crystal orientation changes from single to octal. Furthermore, the Schmid factor and yield stress for crystal orientation are evaluated by using the MD simulation on the standard triangle of stereographic projection.
Evaluation for Probabilistic Distributions of Fatigue Life of Marine Propeller Materials by using a Monte Carlo Simulation
Yoon, Han-Yong ; Zhang, Jianwei ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1055~1062
DOI : 10.3795/KSME-A.2008.32.12.1055
Engineering materials have been studied and developed remarkably for a long time. But, few reports about marine propeller materials are presented. Recently, some researchers have studied the material strength of marine propellers. However, studies on parametric sensitivity and probabilistic distribution of fatigue life of propeller materials have not been made yet. In this study, a method to predict the probabilistic distributions of fatigue life of propeller materials is presented, and the influence of several parameters on the life distribution is discussed.
Development of Failure Pressure Evaluation Model for Local Wall-Thinned Elbows Based on Finite Element Analysis
Kim, Jin-Weon ; Park, Jong-Sun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1063~1071
DOI : 10.3795/KSME-A.2008.32.12.1063
This paper provides a failure pressure evaluation model for local wall-thinned elbows. In this study, parametric finite element analyses are performed on the elbows containing local wall-thinning defect at their intrados and extrados, and the failure pressures are obtained from the analysis results by applying a local failure criterion that was validated by real-scale pipe tests. An evaluation model including the effects of thinning depth, length, circumferential angle, thinning location, and elbow geometries on the failure pressure is derived based on the evaluated failure pressures. The proposed model agrees well with the results of finite element analyses and reasonably estimates the dependence of failure pressure on the wall-thinning dimensions and elbow geometries. Also, the comparison with experimental data demonstrates that the proposed evaluation model can accurately predict the failure pressure of local wall-thinned elbows.
Elastic Analysis of a Half-Plane Containing an Inclusion and a Void Using Mixed Volume and Boundary Integral Equation Method
Lee, Jung-Ki ; Yoon, Koo-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1072~1087
DOI : 10.3795/KSME-A.2008.32.12.1072
A mixed volume and boundary integral equation method (Mixed VIEM-BIEM) is used to calculate the plane elastostatic field in an isotropic elastic half-plane containing an isotropic or anisotropic inclusion and a void subject to remote loading parallel to the traction-free boundary. A detailed analysis of stress field at the interface between the isotropic matrix and the isotropic or orthotropic inclusion is carried out for different values of the distance between the center of the inclusion and the traction-free surface boundary in an isotropic elastic half-plane containing three different geometries of an isotropic or orthotropic inclusion and a void. The method is shown to be very accurate and effective for investigating the local stresses in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions and multiple voids.
A Study on the Improvement of Surface Roughness of Impeller by Selection of Tool Path and Posture and Control of Feedrate
Hwang, Jong-Dae ; Oh, Ji-Young ; Jung, Yoon-Gyo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1088~1095
DOI : 10.3795/KSME-A.2008.32.12.1088
5-axis NC machining has a good advantage of the accessibility of tool motion by adding two rotary axes. It offers numerous advantages such as expanding machining fields in parts of turbo machineries like impeller, propeller, turbine blade and rotor, reasonable tool employment and great reduction of the set-up process. However, as adding two rotary axes, it is difficult to choose suitable machining conditions in terms of tool path, tool posture, feedrate control at a tool tip and post-processing. Therefore in this paper, it is proposed to decide suitable machining condition through an experimental method such as adopting various tool paths, tool postures, and feedrate types. Machining experiment on AL7075 for impeller is performed to define suitable machining condition, and measurement of surface roughness on machined surfaces depended on each machining condition is performed. By defining suitable machining condition, we should have conclusion as improving the surface quality in the aspect of surface roughness and machined shape of surface.
Validation of Flexible Rotor Model for a Large Capacity Flywheel Energy Storage System
Yoo, Seong-Yeol ; Park, Cheol-Hoon ; Choi, Sang-Kyu ; Lee, Jeong-Pil ; Noh, Myoung-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1096~1101
DOI : 10.3795/KSME-A.2008.32.12.1096
When we design a controller for the active magnetic bearings that support a large rotor, it is important to have an accurate model of the rotor. For the case of the flywheel that is used to store energy, an accurate rotor model is especially important because the dynamics change with respect to the running speed due to gyroscopic effects. In this paper, we present a procedure of obtaining an accurate rotor model of a large flywheel energy storage system using finite-element method. The model can predict the first and the second bending mode which match well with the experimental results obtained from a prototype flywheel energy storage system.
Characterization of Microfluidic Channels using DVD Pick-up Fluorescent Scanner
Yim, Vit ; Kim, Jae-Hyun ; Lee, Seung-Yop ; Park, Jung-Yul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1102~1106
DOI : 10.3795/KSME-A.2008.32.12.1102
Microfluidics deals with the behavior, precise control and manipulation of fluids at a micro scale. It has become increasingly prevalent in various applications such as biomedical applications (diagnostics, therapeutics, and cell/tissue engineering), inkjet head, and fuel cells etc. The issue of inspection and characterization of microfluidics has emerged as a major consideration in design, fabrication, and detection of microfluidic devices. In this paper, we characterize a diffusion based mixing in Y-microchannel using a fluorescent optical scanner based on a DVD pick-up module, which is widely used in optical storages. Using fluorescent dye, we measure the fluorescent intensity that represents the mixing patterns in Y-microchannel. We also compare these experimental results with computational fluid dynamics (CFD) simulation ones. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and cost-effectiveness, compared to conventional optical tools such as epifluorescent microscopes using high resolution CCD camera and confocal microscopes with photomultiplier (PMT) detectors.
Effects of Galvannealing Temperatures on Iron-Zn Intermetallic Compounds and Friction Characteristic of Galvannealed Coatings
Lee, Jung-Min ; Kim, Dong-Hwan ; Lee, Seon-Bong ; Kim, Dong-Jin ; Kim, Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1107~1114
DOI : 10.3795/KSME-A.2008.32.12.1107
This paper is aimed to understand the effect of different galvannealing temperatures on the frictional properties and Fe-Zn intermetallic phases of the galvannealed (GA) coatings on steel sheets. Their galvannealing treatments were conducted at 465, 505, 515 and
for about 10s in the additional heating furnace of an industrial continuous hot-dip galvanizing line. The mechanical and the frictional properties of the coatings were estimated using nanoindentation, nanoscratch, micro vickers hardness tests and flat friction tests, which were performed at contact pressures of 4, 20 and 80MPa. Also, the correlation between the microstructure and the frictional properties of the GA coatings were investigated by SEM observation for the cross-section of the GA coating after and before flat friction tests. The results showed that the mechanical and the frictional properties of the coatings are strongly dependent on their phase distributions and microstructure. Especially, in low contact pressure of 4MPa the frictional properties of the coatings were dependent on the surface phases and morphology, while in high contact pressure of 80MPa it was influenced by their mechanical properties based on the dominant phase distributions.
A Study About Microbiochip for Separation of Motile Sperm by Using Chemotaxis
Ko, Yong-Jun ; Maeng, Joon-Ho ; Ahn, Yoo-Min ; Hwang, Seung-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1115~1122
DOI : 10.3795/KSME-A.2008.32.12.1115
This paper presents a new microchip which can separate motile sperm by chemotaxis. The microchip was developed to create longitudinal concentration gradient in the microchannel due to diffusion. Linearly good concentration gradient of chemoattractant was generated without any fluid control devices. In sperm separation experiment with the developed microchip, mouse sperm was used as sample and acetylcholine was selected as chemoattractant. Human tubal fluid (HTF), buffer solution, was introduced into the microchannel of the microchip and attractants diluted in ratio of 1, 1/2, 1/4, 1/8, 1/16, 1/32 and 1/64 including control (DI water) were dropped in each outlet by
volume with micropippet. After 5min,
sperm solution was dropped into inlet of the chip. After 10 min, when sperms reached to the outlet by chemotaxis, we counted sperms in each outlet by using microscopy. Consequently, we could separate progressive motile sperm with the new microchip. In the experiment, the most sperms were isolated at the outlet dropped with 1/16 diluted solution. The optimal concentration gradient to induce chemotaxis was about 0.625 mg/ml/mm.
V-Factor Estimation Under Thermal and Mechanical Stress for Circumferentially Cracked Cylinder
Song, Tae-Kwang ; Oh, Chang-Kyun ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1123~1131
DOI : 10.3795/KSME-A.2008.32.12.1123
This paper provides V-factor estimation under combined mechanical and thermal load for circumferential cracks. Results are based on finite element analyses and effect of types and magnitudes of the thermal stress, crack geometry, the loading mode and plastic strain hardening on variations of the V-factor are investigated. The results of finite element analyses are compared with R6 values. As a result, it is shown that R6 gives generally conservative results. The conservatism is especially increased for the combination of large mechanical and thermal load. As a result, new estimation method which uses failure assessment line in R6 is proposed for V-factor and gives less conservative results.
Local Shape Optimization of Notches in Airframe for Fatigue-Life Extension
Won, Jun-Ho ; Choi, Joo-Ho ; Gang, Jin-Hyuk ; An, Da-Wn ; Yoon, Gi-Jun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1132~1139
DOI : 10.3795/KSME-A.2008.32.12.1132
The aim of this study is to apply shape optimization technique for the repair of aging airframe components, which may extend fatigue life substantially. Free-form optimum shapes of a cracked part to be reworked or replaced are investigated with the objective to minimize the peak local stress concentration or fatigue-damage. Iterative non-gradient method, which is based on an analogy with biological growth, is employed by incorporating the robust optimization method to take account of the stochastic nature of the loading conditions. Numerical examples of optimal hole shape in a flat plate are presented to validate the proposed method. The method is then applied to determine the reworked or replacement shape for the repair of a cracked rib in the rear assembly wing body of aircraft.
A Study on Manufacturing Process Control and Monitoring System for Heat-Shrink-Tube Cutting Machine
Kim, Hyoung-Seok ; Lee, Byung-Ryong ; Yun, Ho-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1140~1145
DOI : 10.3795/KSME-A.2008.32.12.1140
In conventional cutting system of Heat-Shrink-Tube, workers operate cutting system after considering about length and quantity of heat-shrink-tube. So, not only work time and production cost is increased but also material is wasted because the data that workers have to consider is so much. In this paper, an effective cutting system of heat-shrink-tube was developed to reduce production cost, work time and waste of material. The cutting system consists of a supervisory computer installed inside a control room, a on-site computer installed on the work area, and a PLC system. In the developed system, a supervisory computer send work order to the on-site computer using LAN and the on-site computer operates the cutting system of the heatshrink-tube after it makes an array production order. Also, the on-site computer reports information to the supervisory computer when an accident happened.
A Development of Numerical Analysis Software on Dynamic Analysis for Lunching System
Chae, Ae-Kyung ; Bae, Dae-Sung ; Jeon, Hyuck-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1146~1152
DOI : 10.3795/KSME-A.2008.32.12.1146
In the initial stage of guided missile launching, the dynamic stability of a missile is highly influenced by disturbances from the outside and interferences among the launching system parts. This research develops a program for guided missile launching system analysis. Random variables are used to analyze quantitatively the missile characteristic response. An example of results with the program applied into a specific System is presented to demonstrate the effectiveness of the propose method.
Analysis on the Behavior of the Shape Memory Alloy Using Abaqus UMAT
Kim, Young-Jin ; Chung, Jong-Ha ; Lee, Jung-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 12, 2008, Pages 1153~1160
DOI : 10.3795/KSME-A.2008.32.12.1153
In this paper, the algorithm of Abaqus UMAT is introduced to analyze the shape memory alloy. The SMA has two main effects which show non-linearity. Due to this, it is hard to analyze SMA using analysis tools and to describe all of two effects. Therefore, in this study, the program using Abaqus UMAT based on Modified Brinson model is used to analyze SMA. The martensite fraction, the most important factor which defines SMA motion, is also calculated by Fortran program in UMAT. In addition, the tensile test of SMA specimen is conducted. The availability of algorithm is proved by comparing analysis to experimental result.