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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 34, Issue 12 - Dec 2010
Volume 34, Issue 11 - Nov 2010
Volume 34, Issue 10 - Oct 2010
Volume 34, Issue 9 - Sep 2010
Volume 34, Issue 8 - Aug 2010
Volume 34, Issue 7 - Jul 2010
Volume 34, Issue 6 - Jun 2010
Volume 34, Issue 5 - May 2010
Volume 34, Issue 4 - Apr 2010
Volume 34, Issue 3 - Mar 2010
Volume 34, Issue 2 - Feb 2010
Volume 34, Issue 1 - Jan 2010
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Particle Behavior and Deformation During Compaction of Al Powder Using MPFEM
Lee, Kyung-Hun ; Lee, Jung-Min ; Kim, Byung-Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 383~390
DOI : 10.3795/KSME-A.2010.34.4.383
This paper describes multiparticle finite element model (MPFEM)-based powder compaction simulations performed to demonstrate the densification of compacted aluminum powders. A 2D MPFEM was used to explore the densification of a collection of aluminum particles with different average particle sizes under various ram speeds. Individual particles are discretized using a finite element mesh for a detailed description of contact mechanics. Porous aluminum powders with average particle sizes of
were compressed uniaxially at ram speeds of 5, 15, 30, and 60 mm/min by using an MTS servo-hydraulic tester. The slow ram speed was of great advantage to powder densification in low compaction force due to sufficient particle rearrangement. Owing to a decrease in the average particle size of aluminum, the compaction force increased.
Fabrication and Performance Evaluation of Thin Polysilicon Strain Gauge Bonded to Metal Cantilever Beam
Kim, Yong-Dae ; Kim, Young-Deok ; Lee, Chul-Sub ; Kwon, Se-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 391~398
DOI : 10.3795/KSME-A.2010.34.4.391
In this paper, we propose a sensor design by using a polysilicon strain gauge bonded to a metal diaphragm. The fabrication process of the thin polysilicon strain gauges having thicknesses of
was established using conventional MEMS technologies; further, the technique of glass frit bonding of the polysilicon strain gauge to the stainless steel diaphragm was established. Performance of the polysilicon strain gauge bonded to the metal cantilever beam was evaluated. The gauge factor, temperature coefficient of resistance (TCR), nonlinearity, and hysteresis of the polysilicon strain gauge were measured. The results demonstrate that the resistance increases linearly with tensile stress, while it decreases with compressive stress. The value of the gauge factor, which represents the sensitivity of strain gauges, is 34.0; this value is about 7.15 times higher than the gauge factor of a metal-foil strain gauge. The resistance of the polysilicon strain gauge decreases linearly with an increase in the temperature, and TCR is
. Further, nonlinearity and hysteresis are 0.21 % FS and 0.17 % FS, respectively.
Comparative Study of Modeling of Hand Motion by Neural Network and Kernel Regression
Yang, Hac-Jin ; Kim, Hyung-Tae ; Kim, Seong-Kun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 399~405
DOI : 10.3795/KSME-A.2010.34.4.399
The grasping motion of a person's hand for a simplified degree of freedom was modeled by using the photographic motion measured by a high-speed camera. The mathematical expression of distal interphalangeal (DIP) motion was developed by using relation models of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) motions to reduce the degree of freedom. The mathematical expression for humanoid-hand operation obtained using a learning algorithm with a neural network and using a kernel regression model were compared. A feasible model of hand operation was obtained on the basis of comparative data analysis by using the kernel regression model.
Estimation of Mechanical Properties of Tungsten-Fiber-Reinforced Ti-MMCs by Hot Isostatic Pressing
Son, Sun-Young ; Nishida, Shin-Ichi ; Lee, Jong-Hyung ; Kim, Young-Tae ; Lee, Do-Kyung ; Son, Yong-Jea ; Jang, Hyun-Duck ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 407~412
DOI : 10.3795/KSME-A.2010.34.4.407
The objective of this study is the estimation of the mechanical properties of HIP-treated MMCs by an optimized manufacturing process. The Ti-MMCs were fabricated by HIP and rotary swaging (RS) for secondary processing. The Ti-MMCs with different tungsten fiber contents of 0, 6, 9, and 12 vol% were subjected to tensile tests, fatigue tests, and hardness tests. The results show that the hardness values of Ti-MMCs increased with the increasing volume percent of tungsten fibers, the tensile strength increased by approximately 50% (specific strength: 38%) at the 9 vol%. The value of tungsten-fiber orientation F affects the tensile strength. The fatigue strengths of the Ti-MMCs did not improve. HIP is a useful manufacturing method for Ti-MMCs and RS is an important process for improving fiber orientation during secondary processing.
Investigation on the Effect of Strength Mismatch on Residual Stresses in Welds with Different Strength Used in Buried Natural Gas Pipeline
Kim, Jong-Sung ; Kim, Woo-Sik ; Baek, Jong-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 413~421
DOI : 10.3795/KSME-A.2010.34.4.413
In this study, residual-stress distributions in welds with different strength used in natural gas pipelines are calculated by using finite-element analysis and simulating a realistic welding process. The temperature and residual-stress analysis results are compared with the real fusion profile and the application results of the Fitness-For-Service assessment code, API 579 in order to validate the finite-element analysis model and procedure. Parametric study is performed to assess the effect of welding and material variables such as mechanical strength mismatch, the strength of weld metal, reinforcement, and heat input on the residual stress distributions. Finally, on the basis of the parametric study results, the effects of these variables on residual stress distributions are investigated. In particular, the strength mismatch between base metals has an insignificant effect on residual-stress distributions.
Analysis of Filling and Stresses in the Hot Forging Process Depending on Flange Die Shapes
Kim, Jun-Hyoung ; Kim, Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 423~430
DOI : 10.3795/KSME-A.2010.34.4.423
Hot closed-forging process and the die used for forming an automotive flange were analyzed from the viewpoints of heat transfer, grain-flow lines, and stresses to obtain a forged product without defects such as surface cracks, laps, cold shots, and partial filling. The forging process including up-set, pre-forging, final forging and pressing forces was investigated using finite element analysis. The influence of the preform die and the ratio of the heights of the upper die to lower die on the forging process and die were investigated and a die shape (
for the preform die, and 1.5:1 ratio for the final die) suitable to achieve successful forging was determined on the basis of a parametric study. All parametric design requirements such as strength, full filling, and a load limit of 13,000 KN were satisfied for this newly developed flange die. New dies and flanges were fabricated and investigated. Defects such as partial filling and surface cracks were not observed.
Computation of Ground Reaction Forces During Gait using Kinematic Data
Song, Sung-Jae ; Kim, Sei-Yoon ; Kim, Young-Tae ; Lee, Sang-Don ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 431~437
DOI : 10.3795/KSME-A.2010.34.4.431
The purpose of this study is to compute the ground reaction forces during gait in the absence of force plates. The difficulties in using force plates for hemiparetic patients inspired us to initiate this study. Level-walking experiments were performed using a three-dimensional motion analysis system with synchronized force plates. Kinematic data were obtained from the three-dimensional trajectories of reflective markers. Gait events were also detected from the kinematic data. The human body was modeled as 13 rigid segments. The mass and the center of mass of each segment were determined from anthropometric data. Vertical ground-reaction forces obtained from the kinematic data were in good agreement with those obtained using the force plate. The computed and measured values of anterior and lateral ground reaction showed similar tendencies. The computation results can be used as the basic data for inverse dynamic analysis.
Analysis of Fatigue Life and Failure of High-Speed Rotating Cylindrical Vessel with Holes
Lee, Ouk-Sub ; Kim, Hong-Min ; Choi, Hye-Bin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 439~446
DOI : 10.3795/KSME-A.2010.34.4.439
Fracture mechanics is used for the detailed analysis of the failure of high-speed rotating cylindrical vessels. The general procedure for the analysis of fatigue life and failure used in this study is summarized; the initial material properties are also described. The results of the theoretical stress analysis are compared to the observed magnitude of the stress under the operational condition. The fracture-surface configurations observed under both optical and scanning electron microscopes are used to investigate the progress of fatigue crack propagation. Fatigue life estimates obtained by using the Paris model are compared to the actual service life of the high-speed rotating pressure vessel.
Study on Estimation of Design Factors for 6 Degree-of-Freedom Simulator
Yoon, Jun-Seok ; Song, Woo-Jin ; Byun, Young-Seop ; Ku, Tae-Wan ; Kim, Jeong ; Kang, Beom-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 447~456
DOI : 10.3795/KSME-A.2010.34.4.447
The application of a reliable motion simulator can contribute effectively in the evaluation of the performance of a vehicle platform in the development stage of a small unmanned aerial vehicle (UAV). Therefore, the research on a reliable motion simulator can accelerate the development of UAV and decrease the relevant cost. In this paper, the design factors considered in the preliminary design stage of a 6 degree-of freedom motion simulator are defined and the motion range of the simulator is described on the basis of these design factors. The length, acceleration, and the required thrust of actuators with respect to the motion simulator under development are also predicted. The motion range can be increased and a suitable actuator can be selected and produced by applying these results in the manufacturing process of the motion simulator. Thus, the reliability of the motion simulators can be achieved during the actual design operation of the UAV.
Taylor Series-Based Long-Term Creep-Life Prediction of Alloy 617
Yin, Song-Nan ; Kim, Woo-Gon ; Park, Jae-Young ; Kim, Soen-Jin ; Kim, Yong-Wan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 457~465
DOI : 10.3795/KSME-A.2010.34.4.457
In this study, a Taylor series (T-S) model based on the Arrhenius, McVetty, and Monkman-Grant equations was developed using a mathematical analysis. In order to reduce fitting errors, the McVetty equation was transformed by considering the first three terms of the Taylor series equation. The model parameters were accurately determined by a statistical technique of maximum likelihood estimation, and this model was applied to the creep data of alloy 617. The T-S model results showed better agreement with the experimental data than other models such as the Eno, exponential, and L-M models. In particular, the T-S model was converted into an isothermal Taylor series (IT-S) model that can predict the creep strength at a given temperature. It was identified that the estimations obtained using the converted ITS model was better than that obtained using the T-S model for predicting the long-term creep life of alloy 617.
Accelerated Life Prediction for STS301L Gas Welded Joint (I) - Fillet Type -
Baek, Seung-Yeb ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 467~474
DOI : 10.3795/KSME-A.2010.34.4.467
Stainless steel sheets are widely used as the structural material for railroad cars and commercial vehicles. Structures made of stainless steel sheets are commonly fabricated by gas welding, For the fatigue design of gas welded joints such as fillet joints, it is necessary to obtain design information of the stress distribution at the weldment as well as the fatigue strength of the gas-welded joints. Further, the influence of the geometrical parameters of gas-welded joints on stress distribution and fatigue strength must be evaluated. in this study,
curves were obtained by fatigue tests. and, the
curves were rearranged on the basis of the
relation for the hot-spot stresses at the gas-welded joints. These results, were used for conducting an accelerated life test(ALT) From the experiment results, an acceleration model was derived and factors were estimated. The objective is to obtain the information required for the analysis of the fatigue lifetime of fillet welded joints and for data analysis by the statistic reliability method to save time and cost and to develop optimum accelerated life prediction plans.
Evaluation of Degradation of Isothermally Aged Plasma-Sprayed Thermal Barrier Coating
Koo, Jae-Mean ; Seok, Chang-Sung ; Kang, Min-Sung ; Kim, Dae-Jin ; Lee, Dong-Hoon ; Kim, Mun-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 475~480
DOI : 10.3795/KSME-A.2010.34.4.475
The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature; delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature
Study of Failure Criterion of Hole-Notched Plain-Weave Carbon Fiber Reinforced Plastic (CFRP) Composites
Kim, Sang-Young ; Geum, Jin-Hwa ; Koo, Jae-Mean ; Seok, Chang-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 481~486
DOI : 10.3795/KSME-A.2010.34.4.481
Recently, carbon fiber reinforced plastic (CFRP) have been used in various fields because of its high specific modulus, and chemical properties. Most products in which CFRP composites are used are manufactured by joining the product components by bolts or pins. Holes for bolts and pins decrease the strength of the components because these holes act as notches in the structures. In this study, the fracture strength of CFRP plain-weave composite plates containing holes is experimentally investigated to examine the effects of hole-size and specimen width on notched tensile strength. The results show that the characteristic length considered in the point stress criterion depends on the hole size and specimen width. There exists a certain relation between notched tensile strength and characteristic length. Fracture criterion is redefined on basis of this relation.
Development of an Inverse Method Using Orthogonal Basis Functions for the Evaluation of Boundary Tractions on an Elastic Body
Kim, Sa-Young ; Kim, Hyun-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 487~493
DOI : 10.3795/KSME-A.2010.34.4.487
Most structural analyses are concerned with the deformations and stresses in a body subjected to external loads. However, in many fields, inverse problems have to be interpreted to determine surface tractions or internal stresses from displacements measured on a remote surface. In this study, the inverse processes are studied by using the finite element method for the evaluation of internal stresses. Small errors in the measured displacements often result in a substantial loss of stability of an inverse system. In order to improve the stability of the inverse system, the displacements on a section near the region of the unknown tractions are predicted by using orthogonal basis functions. We use the Gram-Schmidt orthogonal technique to determine two bases for the displacements on a section near the region of the unknown tractions. Advantages over previous methods are discussed by using numerical examples.
Development of the Regulatory Guidelines for Continued Operation of CANDU Reactor in Korea
Choi, Young-Hwan ; Kim, Hong-Key ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 495~499
DOI : 10.3795/KSME-A.2010.34.4.495
In this paper, the regulatory guidelines for the continued operation of the CANDU reactor in Korea were introduced. Wolsong Unit 1, which is a CANDU 600 reactor in Korea, will reach its design life of 30 years in 2012. A licensee who wants to operate a nuclear power plant beyond its design life should submit reports of periodic safety reviews (PSRs) conducted on the basis of 11 safety factors. In addition, the licensee should provide the following: (1) scoping and screening results for aging management, (2) aging management program, (3) TLAA, including the continued operation term, (4) operation-experience feedback, and (5) important safety-research results. In this study, 54 regulatory guidelines for the five above-mentioned items for the CANDU reactor in Korea were developed.
Numerical Analysis for Nonlinear Static and Dynamic Responses of Floating Crane with Elastic Boom
Cha, Ju-Hwan ; Park, Kwang-Phil ; Lee, Kyu-Yeul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 34, issue 4, 2010, Pages 501~509
DOI : 10.3795/KSME-A.2010.34.4.501
A floating crane is a crane-mounted ship and is used to assemble or to transport heavy blocks in shipyards. In this paper, the static and dynamic response of a floating crane and a heavy block that are connected using elastic booms and wire ropes are described. The static and dynamic equations of surge, pitch, and heave for the system are derived on the basis of flexible multibody system dynamics. The equations of motion are fully coupled and highly nonlinear since they involve nonlinear mass matrices, elastic stiffness matrices, quadratic velocity vectors, and generalized external forces. A floating frame of reference and nodal coordinates are employed to model the boom as a flexible body. The nonlinear hydrostatic force, linear hydrodynamic force, wire-rope force, and mooring force are considered as the external forces. For numerical analysis, the Hilber-Hughes-Taylor method for implicit integration is used. The dynamic responses of the cargo are analyzed with respect to the results obtained by static and numerical analyses.