Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of the Korean Society of Mechanical Engineers A
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
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
Selecting the target year
Muscle-Inspired Serially-Connected Digital Actuators for Low-Voltage, Wide-Range, High-Precision Displacement Control
Lee, Jae-Yong ; Lee, Won-Chul ; Cho, Young-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 1~6
DOI : 10.3795/KSME-A.2008.32.1.001
This paper presents muscle-inspired serial digital actuators, achieving the improvement of the range-to-precision and range-to-voltage performance. We propose a weight-balanced design for the serial actuators with serpentine springs using serial arrangement of digital actuators. We have measured the displacement range, precision, and drive voltage at unit and serial actuation of 1Hz. The serial digital actuators produce a full range displacement of
, accumulating the unit displacement of
at the operating voltage of
. In addition, the serial digital actuators having the displacement precision of
do not accumulate the precision of the unit actuators,
. We experimentally verify that the serial digital actuators achieve the range-to-squared-voltage ratio of
and the range-to-precision ratio of 749.6.
Effects of Electrode Configurations on the Characteristics of Axial Magnetic Fields in Vacuum Interrupter
Hwang, Jung-Hoon ; Lee, Jong-Chul ; Kim, Youn-Jea ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 7~12
DOI : 10.3795/KSME-A.2008.32.1.007
The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compacted environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the effect of changing geometrical parameters for electromagnetic behaviors of high-current vacuum arcs with two different types of AMP contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.
Effect of Acid Fog on Rust Formation and Fatigue Behavior of Weathering Steel Used in Un-Coated Bridge
Kim, Min-Gun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 13~20
DOI : 10.3795/KSME-A.2008.32.1.013
The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.
Mathematical Expressions for Stress-Strain Curve of Metallic Material
Hyun, Hong-Chul ; Lee, Jin-Haeng ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 21~28
DOI : 10.3795/KSME-A.2008.32.1.021
Stress-strain curves based on Ramberg-Osgood and Hollomon relations are strongly dependent upon the regressed range of strain. This work investigates mathematical expressions of true stress-strain curves of metallic materials. We first observe the variation of yield strength, strain hardening exponent and stress-strain curve with regressed range of stain. Based on sectional regression and expression using one or two parameters, we propose an optimal strain range for which yield strength and nonlinear material behavior are quite appropriate.
The Efficient Sensitivity Analysis on Statistical Moments and Probability Constraints in Robust Optimal Design
Huh, Jae-Sung ; Kwak, Byung-Man ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 29~34
DOI : 10.3795/KSME-A.2008.32.1.029
The efforts of reflecting the system's uncertainties in design step have been made and robust optimization or reliability-based design optimization are examples of the most famous methodologies. In their formulation, the mean and standard deviation of a performance function and constraints expressed by probability conditions are involved. Therefore, it is essential to effectively and accurately calculate them and, in addition, the sensitivity results are required to obtain when the nonlinear programming is utilized during optimization process. We aim to obtain the new and efficient sensitivity formulation, which is based on integral form, on statistical moments such as the mean and standard deviation, and probability constraints. It does not require the additional functional calculation when statistical moments and failure or satisfaction probabilities are already obtained at a design point. Moreover, some numerical examples have been calculated and compared with the exact solution or the results of Monte Carlo Simulation method. The results seem to be very satisfactory.
A Numerical Approach to Young's Modulus Evaluation by Conical Indenter with Finite Tip-Radius
Lee, Jin-Haeng ; Kim, Deok-Hoon ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 35~42
DOI : 10.3795/KSME-A.2008.32.1.035
Instrumented sharp indentation test is a well-directed method to measure hardness and elastic modulus. The sharp indenter such as Berkovich and conical indenters have a geometrical self-similarity in theory, but the self-similarity ceases to work in practice due to inevitable indenter tip-blunting. In this study we analyzed the load-depth curves of conical indenter with finite tip-radius via finite element method. Using the numerical regression data obtained from Kick's law, we first confirmed that loading curvature is significantly affected by tip radius as well as material properties. We then established a new method to evaluate Young's modulus, which successfully provides the value of elastic modulus with an average error of less than 2%, regardless of tip-radius and material properties of both indenter and specimen.
Green's Function of Edge Crack in Transversely Isotropic Piezoelectric Material Under Anti-Plane Loads
Choi, Sung-Ryul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 43~53
DOI : 10.3795/KSME-A.2008.32.1.043
Surface edge crack in transversely isotropic piezoelectric material is analyzed. The concentrated antiplane mechanical and inplane electrical loadings are applied to an arbitrary point of the surface, where the impermeable crack boundary condition is imposed. Using Mellin transform the problem is formulated, from which Wiener-Hopf equations are derived. By solving the equations the solution is obtained in a closed form. Mechanical and electric intensity factors and energy release rate are obtained and discussed. This problem could be used as a Green's function to generate the solutions of other problems with the same geometry but of different loading conditions.
Fretting Wear Simulation of Press-Fitted Shaft with Finite Element Analysis and Influence Function Method
Lee, Dong-Hyong ; Kwon, Seok-Jin ; Choi, Jae-Boong ; Kim, Young-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 54~62
DOI : 10.3795/KSME-A.2008.32.1.054
In this paper the fretting wear of press-fitted specimens subjected to a cyclic bending load was simulated using finite element analysis and numerical method. The amount of microslip and contact variable at press-fitted and bending load condition in a press-fitted shaft was analysed by applying finite element method. With the finite element analysis result, a numerical approach was applied to predict fretting wear based on modified Archard's equation and updating the change of contact pressure caused by local wear with influence function method. The predicted wear profiles of press-fitted specimens at the contact edge were compared with the experimental results obtained by rotating bending fatigue tests. It is shown that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact variables are redistributed. The work establishes a basis for numerical simulation of fretting wear on press fits.
Fatigue Test and Simulation on the Steel Welded L-Shaped Frame
Lee, Jung-Hee ; Kim, Jae-Hoon ; Kong, Jeong-Pyo ; Han, Kyu-Hyun ; Lee, Young-Shin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 63~69
DOI : 10.3795/KSME-A.2008.32.1.063
A fatigue test on the steel welded L-shaped frame was conducted. The frame was consisted with carbon steel tube and reinforced bracket. The four type reinforced brackets were fabricated. They were two rectangular plate reinforced bracket, two sided pentagon plate reinforced bracket, triangular plate reinforced bracket and fully reinforced bracket. The fatigue test of frame was conducted with axial tension loading. The fatigue simulation of the steel welded L-shaped frame was also performed by the finite element method with code FEMFAT. The frame of fully reinforced bracket had the highest fatigue life and reinforced quality factor.
Analysis of Compressive Characteristics of Wire-woven Bulk Kagome
Lee, Byung-Kon ; Choi, Ji-Eun ; Kang, Ki-Ju ; Jeon, In-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 70~76
DOI : 10.3795/KSME-A.2008.32.1.070
Periodic cellular metals (PCMs) are actively being investigated because of their excellent specific strength and stiffness, and multi-functionality such as a heat disperse structure bearing external loading. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling and lower anisotropy than other truss PCMs. In this paper, the out-of-plane compressive responses of the WBK specimens have been measured, theoretically predicted and numerically analyzed. Three specimens of two-layered WBK are fabricated and tested for measuring the responses. The peak stress of compressive behavior and effective elastic modulus are predicted based on the equilibrium equation and elastic energy conservation. Moreover, the structure of the specimen is modeled using the commercial mesh generation code, PATRAN and the finite element analysis for the model under the compression is carried out using the commercial FE code, ABAQUS. Finally, the obtained results are compared with each other to analyze the compressive characteristics of Wire-woven Bulk Kagome (WBK).
Online Strain Measurement at Multiple Points on a Rotating Blade with Fiber Bragg Grating Sensors and a Rotary Optical Coupler
Lee, Jong-Min ; Hwang, Yo-Ha ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 77~82
DOI : 10.3795/KSME-A.2008.32.1.077
Strain-gauges have been dominantly used to measure strain at various points on a rotor, however, either a slip ring or telemetry has to be used to send sensor signals to data acquisition instruments at stationary side. Both slip ring and telemetry have numerous inherent problems which force severe limitations in real applications. This paper introduces a new rotor condition monitoring system using FBG(Fiber Bragg Grating) sensors and a rotary optical coupler. A single optical fiber with many FBG sensors is installed on the rotor and an optical dynamic interrogator is installed at stationary side. The sensor signal connection between rotating part and stationary part is made by the rotary optical coupling method which makes use of light's unique characteristic-light travels through space. Broad band light source from the interrogator travels to the optical fiber on the rotor and reflected FBG sensor signals travel back to the optical fiber on stationary side and are connected to the interrogator. Rotary optical coupler's insertion loss change due to rotation is compensated by using a reference sensor installed at the center of the rotor. The proposed system's performance has been successfully demonstrated by accurately measuring strains at 5 points on a blade rotating at high speed.
A Study on the Dynamic and Impact Analysis of Side Kick in Taekwondo
Lee, Jung-Hyun ; Han, Kyu-Hyun ; Lee, Hyun-Seung ; Lee, Eun-Yup ; Lee, Young-Shin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 83~90
DOI : 10.3795/KSME-A.2008.32.1.083
Taekwondo is a martial art form and sport that uses the hands and foot for attack and defense. Taekwondo basic motion is composed of the breaking, competition and poomsea motion. In the side kick among the competition motion, the impact force is larger than other kinds of kicks. The side kick with the front foot can be made in two steps. In the first step, the front foot is stretched forward from back stance free-fighting position. For the second step, the rear foot is followed simultaneously. Then, the kick is executed while entire body weight rests on the rear foot. In this paper, impact analysis of the human model for hitting posture is carried out. The ADAMS/LifeMOD is used in hitting modeling and simulation. The simulation model creates the human model to hit the opponent. As the results, the dynamic analysis of human muscle were presented.
Fracture Analysis of a Spindle in the X-Lift
Chu, Seok-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 32, issue 1, 2008, Pages 91~98
DOI : 10.3795/KSME-A.2008.32.1.091
One of the two spindles in the X-lift fractured suddenly during normal operation. The fracture occurred at the notch where the bending moment might be the maximum. Macrofractographic features associated with rotating-bending fatigue are evident on the fracture surface. The 3-D finite element analysis of the X-lift reveals that the spindle rotated under bending. The measured surface strain of the spindle varies cyclically as the spindle rotates. It supports that the spindle rotated under bending. The X-lift is not perfectly symmetrical with respect to both the horizontal and the vertical plane. The slightly unsymmetrical deformation can cause the bending of the spindle.