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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 37, Issue 12 - Dec 2013
Volume 37, Issue 11 - Nov 2013
Volume 37, Issue 10 - Oct 2013
Volume 37, Issue 9 - Sep 2013
Volume 37, Issue 8 - Aug 2013
Volume 37, Issue 7 - Jul 2013
Volume 37, Issue 6 - Jun 2013
Volume 37, Issue 5 - May 2013
Volume 37, Issue 4 - Apr 2013
Volume 37, Issue 3 - Mar 2013
Volume 37, Issue 2 - Feb 2013
Volume 37, Issue 1 - Jan 2013
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Comparative Study on DAE Solution Methods for Effective Multi-Body Dynamics Analysis of Unmanned Military Robot Based on Subsystem Synthesis Method
Kim, Myoung Ho ; Kim, Sung-Soo ; Yun, Hong-Seon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1069~1075
DOI : 10.3795/KSME-A.2013.37.9.1069
An effective method is necessary for the real-time analysis of an unmanned military robot. To achieve highly efficient simulations, a subsystem synthesis method has been developed. The subsystem synthesis method separately generates equations of motion for the base body and for the subsystem. The equations of motion are expressed by DAE, which consist of differential equations and algebraic equations. To increase the accuracy and efficiency of solutions, DAE solvers such as the Direct, CS (Constraint Stabilization), and GCP (Generalized Coordinate Partitioning) method are employed. In this study, the subsystem synthesis method is applied for effective multi-body dynamics analysis of an unmanned military robot, and a comparative study of three different DAE solvers is carried out.
Development of Racing Track Cycle for Elite Players Considered Stiffness and Aerodynamic Effects
Kim, Taekyun ; Lim, Woochul ; Lee, Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1077~1082
DOI : 10.3795/KSME-A.2013.37.9.1077
To improve cycling performance, the power output of the rider and the sources of resistance (e.g., air resistance, frame stiffness, and cycle mass) must be considered. From a mechanical viewpoint, we consider how the bike frame performance can be increased while decreasing the resistance. First, to improve the competitive ability of a racing track cycle, we should consider the stiffness of the bike frame including the pedal loading and aerodynamic effects when riding. Therefore, we obtained the cross-sectional area of each part of the bike frame and then aimed to minimize the drag force through an aerodynamic parametric study. In addition, the frame should remain safe under the loading applied by the rider. Under the guidelines of the UCI (union Cycliste Internationale) regulations, the bike frame has been evaluated under the proposed loading condition, and we developed a racing track cycle for elite cyclists.
Study on Penetration Characteristics of Tungsten Cylindrical Penetrator
Jo, Jong Hyun ; Lee, Young Shin ; Kim, Jae Hoon ; Bae, Yong Woon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1083~1091
DOI : 10.3795/KSME-A.2013.37.9.1083
The design of missile require extremely small warheads that must be highly efficient and lethal. The penetration characteristics of each penetrator and the total number of penetrators on the warhead are obvious key factors that influence warhead lethality. The design of the penetrator shape and size are directly related to the space and weight of the warhead. The design of the penetrator L/D was directly related to the space and weight of the warhead. L and D are the length and the diameter of the projectile, respectively. The AUTODYN-3D code was used to study the effect of penetrator penetration. The objective of numerical analysis was to determine the penetration characteristics of penetrator produced by hypervelocity impacts under different initial conditions such as initial velocity, obliquity angle and L/D of penetrator. The residual velocity and residual mass were decreased with increasing initial impact velocity under
Development of Intelligent Multiple Camera System for High-Speed Impact Experiment
Chung, Dong Teak ; Park, Chi Young ; Jin, Doo Han ; Kim, Tae Yeon ; Lee, Joo Yeon ; Rhee, Ihnseok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1093~1098
DOI : 10.3795/KSME-A.2013.37.9.1093
A single-crystal sapphire is used as a transparent bulletproof window material; however, few studies have investigated the dynamic behavior and fracture properties under high-speed impact. High-speed and high-resolution sequential images are required to study the interaction of the bullet with the brittle ceramic materials. In this study, a device is developed to capture the sequence of high-speed impact/penetration phenomena. This system consists of a speed measurement device, a microprocessor-based camera controller, and multiple CCD cameras. By using a linear array sensor, the speed-measuring device can measure a small (diameter: up to 1 2 mm) and fast (speed: up to Mach 3) bullet. Once a bullet is launched, it passes through the speed measurement device where its time and speed is recorded, and then, the camera controller computes the exact time of arrival to the target during flight. Then, it sends the trigger signal to the cameras and flashes with a specific delay to capture the impact images sequentially. It is almost impossible to capture high-speed images without the estimation of the time of arrival. We were able to capture high-speed images using the new system with precise accuracy.
Study on Weight Reduction of Urban Transit Carbody Based on Material Changes and Structural Optimization
Cho, Jeong Gil ; Koo, Jeong Seo ; Jung, Hyun Seung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1099~1107
DOI : 10.3795/KSME-A.2013.37.9.1099
This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.
Spatial Randomness of Fatigue Crack Growth Rate in Friction Stir Welded 7075-T651 Aluminum Alloy Welded Joints (Case of LT Orientation Specimen)
Jeong, Yeui Han ; Kim, Seon Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1109~1116
DOI : 10.3795/KSME-A.2013.37.9.1109
This study aims to investigate the spatial randomness of fatigue crack growth rate for the friction stir welded (FSWed) 7075-T651 aluminum alloy joints. Our previous fatigue crack growth test data are adopted in this investigation. To clearly understand the spatial randomness of fatigue crack growth rate, fatigue crack growth tests were conducted under constant stress intensity factor range (SIFR) control testing. The experimental data were analyzed for two different materials-base metal (BM) and weld metal (WM)-to investigate the effects of spatial randomness of fatigue crack growth rate and material properties, the friction stir welded (FSWed) 7075-T651 aluminum alloy joints, namely weld metal (WM) and base metal (BM). The results showed that the variability, as evaluated by Weibull statistical analysis, of the WM is higher than that of the BM.
Numerical and Experimental Approach to Investigate Plane-view Shape and Crop Loss in Multistage Plate Rolling
Byon, Sang Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1117~1125
DOI : 10.3795/KSME-A.2013.37.9.1117
A finite element based approach that can be used to investigate the plane-view shape and crop loss of a material during plate rolling is presented. We employed a three-dimensional finite element model to continuously simulate the shape change of the head and tail of a plate as the number of rolling passes increases. The main feature of the proposed model lies in the fact that the multistage rolling can be simulated without a break because the rolling direction of the material is reversibly controlled as the roll gap sequentially decreases. The material constants required in the finite element analysis were experimentally obtained by hot tensile tests. We also performed a pilot hot plate rolling test to verify the usefulness of the proposed finite element model. Results reveal that the computed plane-view shapes as well as crop losses by the proposed finite element model were in good agreement with the measured ones. The crop losses predicted by the proposed model were within 5% of those measured from the pilot hot plate rolling test.
Development of User Subroutine Program Considering Effect of Neutron Irradiation on Mechanical Material Behavior of Austenitic Stainless Steels
Kim, Jong Sung ; Jhung, Myung Jo ; Park, Jeong Soon ; Oh, Young Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1127~1132
DOI : 10.3795/KSME-A.2013.37.9.1127
The failure of reactor internals may have a significant effect on the safe operation and shutdown of a reactor. Various agings related to neutron irradiation occur or can potentially occur in the reactor internals owing to high neutron irradiation levels. Austenitic stainless steel, one of the principal materials constituting the reactor internals, shows different mechanical material behaviors such as tensile/creep properties and fracture toughness with neutron irradiation levels. This variation should be considered when the structural integrity of the reactor internals against agings during the design lifetime or continued operation period is evaluated. In this study, user subroutine programs considering the variation of mechanical material behaviors with neutron irradiation levels were developed. The programs were validated by testing them for various conditions.
Probabilistic Calibration of Computer Model and Application to Reliability Analysis of Elasto-Plastic Insertion Problem
Yoo, Min Young ; Choi, Joo Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1133~1140
DOI : 10.3795/KSME-A.2013.37.9.1133
A computer model is a useful tool that provides solution via physical modeling instead of expensive testing. In reality, however, it often does not agree with the experimental data owing to simplifying assumption and unknown or uncertain input parameters. In this study, a Bayesian approach is proposed to calibrate the computer model in a probabilistic manner using the measured data. The elasto-plastic analysis of a pyrotechnically actuated device (PAD) is employed to demonstrate this approach, which is a component that delivers high power in remote environments by the combustion of a self-contained energy source. A simple mathematical model that quickly evaluates the performance is developed. Unknown input parameters are calibrated conditional on the experimental data using the Markov Chain Monte Carlo algorithm, which is a modern computational statistics method. Finally, the results are applied to determine the reliability of the PAD.
Study on Effect of LSP Process Parameters Using Dimensionless Analysis
Kim, Ju Hee ; Kim, Tae Yang ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1141~1149
DOI : 10.3795/KSME-A.2013.37.9.1141
Dimensional analysis is an important tool for developing mathematical models of physical phenomena in order to understand the effects of laser shock peening(LSP) process parameters. By using the Bucking
theorem, we proposed an applicable dimensional analysis method to verify the effects of LSP process parameters on the residual stresses. Furthermore, by using finite element analysis, we proposed a finite element method of LSP and discussed various parameters, such as peak pressure, pressure pulse duration, laser spot size, and multiple LSPs.
Reliability Evaluation Through Moisture Sorption Characterization of Electronic Packaging Materials
Park, Heejin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1151~1158
DOI : 10.3795/KSME-A.2013.37.9.1151
Knowledge of the moisture sorption properties of a material is essential for optimal material development and analysis of the delamination failure caused by vapor pressure at the interlayer during the manufacturing process of integrated packaging devices. In this paper, both temperature dependent absorption and desorption properties according to temperature and humidity model are parameterized and the effects of water activities and temperature are discussed. The activation energy obtained from the parameterized diffusivity determines the acceleration factor for the equivalency of moisture sorption levels, which enables the effect of moisture diffusivity on the equivalent elapsed testing time required for evaluating the reliable life time to be estimated. The acceleration factor evaluated at the reliability testing standard of the flexible packaging module is exampled.
Effect of Normal Operating Condition Analysis Method for Weld Residual Stress of CRDM Nozzle in Reactor Pressure Vessel
Nam, Hyun Suk ; Bae, Hong Yeol ; Oh, Chang Young ; Kim, Ji Soo ; Kim, Yun Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1159~1168
DOI : 10.3795/KSME-A.2013.37.9.1159
In pressurized water nuclear reactors (PWRs), the reactor pressure vessel (RPV) upper head contains penetration nozzles that use a control rod drive mechanism (CRDM). The penetration nozzle uses J-groove weld geometry. Recently, the occurrence of cracking in alloy 600 CRDM penetration nozzle has increased. This is attributable to primary water stress corrosion cracking (PWSCC). PWSCC is known to be susceptible to the welding residual stress and operational stress. Generally, the tensile residual stress is the main factor contributing to crack growth. Therefore, this study investigates the effect on weld residual stress through different analysis methods for normal operating conditions using finite element analysis. In addition, this study also considers the effect of repeated normal operating condition cycles on the weld residual stress. Based on the analysis result, this paper presents a normal operating condition analysis method.
Reliability Analysis of Mechanical Component with Multiple Failure Modes
Chang, Mu Seong ; Choi, Byung Oh ; Kang, Bo Sik ; Park, Jong Won ; Lee, Choong Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1169~1174
DOI : 10.3795/KSME-A.2013.37.9.1169
Most products are indeed governed by multiple failure modes. However, there are few cases in which reliability analysis applies to only one failure mode at a time. Furthermore, reliability data do not include information about failure modes, or the reliability analysis is performed using a representative failure mode. The Weibull shape parameter for failure modes is more important than one for products in the reliability qualification test. This paper presents reliability analysis methods for a mechanical component with multiple failure modes. These methods include the competing failure modes (CFM) method and the mixed Weibull method. Pneumatic cylinder test data with three failure modes are presented to estimate the shape parameter for each separate failure mode. In addition, reliability measures (B10 life, characteristic life) of the pneumatic cylinder considering three failure modes were compared with those assuming a single failure mode.
Evaluation of Improvement of Detection Capability of Infrared Thermography Tests for Wall-Thinning Defects in Piping Components by Applying Lock-in Mode
Kim, Jin Weon ; Yun, Kyung Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1175~1182
DOI : 10.3795/KSME-A.2013.37.9.1175
The lock-in mode infrared thermography (IRT) technique has been developed to improve the detection capability of defects in materials with high thermal conductivity, and it has been shown to provide better detection capability than conventional active IRT. Therefore, to investigate the application of this technique to nuclear piping components, lock-in mode IRT tests were conducted on pipe specimens containing simulated wall-thinning defects. Phase images of the wall-thinning defects were obtained from the tests, and they were compared with thermal images obtained from conventional active IRT tests. It showed that the ability to size the detected wall-thinning defects in piping components was improved by using lock-in mode IRT. The improvement was especially apparent when detecting short and narrow defects and defects with slanted edges. However, the detection capability for shallow wall-thinning defects did not improve much when using lock-in mode IRT.
Study of Wear Characteristics of Hydraulic Equipment Used in Power Plants
Lee, Yong Bum ; Lee, Gi Chun ; Chang, Mu Seong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1183~1188
DOI : 10.3795/KSME-A.2013.37.9.1183
The reliability of hydraulic equipment used in power plants is especially important because failures that occur in the power plant can have a great ripple effect on human lives and financial losses. In this study, specimens using the materials used in the spool and sleeve of hydraulic valves of power plants have been produced, heat-treated, and tested under the precipitation conditions of phosphate ester hydraulic fluid with a variety of conditions. 23 full factorial designs have been applied to evaluate the significance of factors that affect the wear loss of the specimen, specifically, the load, velocity, and temperature. The significance evaluation was performed on the main effects and two-way interactions for wear loss based on the experiment results, and the mathematical equations between the wear loss and the three factors were derived from the analysis results.
Evaluation of High-Temperature Structural Integrity Using Lab-Scale PCHE Prototype
Song, Kee Nam ; Hong, Sung Deok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 37, issue 9, 2013, Pages 1189~1194
DOI : 10.3795/KSME-A.2013.37.9.1189
The Intermediate Heat Exchanger (IHX) of a Very High Temperature Reactor (VHTR) is a core component that transfers the high heat of
generated in the VHTR to a hydrogen production plant. The Korea Atomic Energy Research Institute manufactured a lab-scale prototype of a Printed Circuit Heat Exchanger (PCHE) as a candidate for an IHX. In this study, as a part of a high-temperature structural integrity evaluation of the lab-scale PCHE prototype made of SUS316L, we carried out high temperature structural analysis modeling and macroscopic thermal and elastic structural analysis for the lab-scale PCHE prototype under helium experimental loop (HELP) test conditions as a precedent study prior to the performance test in HELP.