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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 35, Issue 12 - Dec 2011
Volume 35, Issue 11 - Nov 2011
Volume 35, Issue 10 - Oct 2011
Volume 35, Issue 9 - Sep 2011
Volume 35, Issue 8 - Aug 2011
Volume 35, Issue 7 - Jul 2011
Volume 35, Issue 6 - Jun 2011
Volume 35, Issue 5 - May 2011
Volume 35, Issue 4 - Apr 2011
Volume 35, Issue 3 - Mar 2011
Volume 35, Issue 2 - Feb 2011
Volume 35, Issue 1 - Jan 2011
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Dielectric Breakdown Analysis of Bone-Like Materials with Conductive Channels
Lee, Bo-Hyun ; Lin, Song ; Beom, Hyeon-Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 583~589
DOI : 10.3795/KSME-A.2011.35.6.583
The dielectric breakdown of bone-like materials subject to purely electric fields is investigated. In general, these materials consist of some layers with stronger dielectric strength and others with weaker dielectric strength in a parallel staggered pattern. The growth of the conductive channel is impeded during penetration of the weaker layer in the bone-like material because the electric-field concentration is relieved. The electric-field distribution around the head of the tubular channel is obtained from finite element analysis. The dielectric strength of the bone-like material is evaluated using the J integral, and some parameters affecting the dielectric strength are determined. It is shown that the J-integral values are reduced with an increase in the breakdown area in the weaker layer. It is also found that the ratio of the permittivity of the weaker layer to that of the stronger layer can strongly affect the dielectric breakdown.
A Study of Running Safety According to the Section Shape of an F10/F12 Turnout
Kim, Sung-Jong ; Eom, Beom-Gyu ; Kang, Bu-Byoung ; Lee, Hi-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 591~598
DOI : 10.3795/KSME-A.2011.35.6.591
When a vehicle passes through a turnout, it is necessary for the changes in lateral force to be minimized to ensure the safe running of the vehicle. Therefore, the analysis of the interaction between the vehicle and the turnout is crucial for estimating the lateral force and the derailment coefficient on the turnout. In this paper, the effect of the variation of section shape on the running safety of a vehicle was investigated by changing the shape of the point part and the crossing part. The tongue rail length of the point part and nose rail height of the crossing part of an F10/F12 turnout were changed, and the running safety of the vehicle was analyzed.
Mechanism and Control of Reaction Force Compensation of XY Linear Motion Stage System
Cho, Kyu-Jung ; Choi, Dong-Soo ; Ahn, Hyeong-Joon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 599~607
DOI : 10.3795/KSME-A.2011.35.6.599
In this paper, a reaction-force compensation system for an XY linear motion stage, without an additional external isolation structure or extra motors, is developed. This system consists of a movable magnet track, a spring, a dummy weight, and a dedicated sensor module that measures the relative positions of the movable magnet track with respect to the motor coil. The reaction force compensation system is modeled, and simulations are carried out to optimize design parameters such as the moving distance of the magnet track, the transmission force, the dummy weight, and the allowed size of the mechanism. An XY linear motion stage is built, incorporating the reaction force compensation system, and the performance of the system is verified experimentally. For acceleration and deceleration values of 10 m/
, 85% of the reaction force is absorbed by the reaction force compensation system.
Estimation of C(t) -Integral Under Transient Creep Conditions for a Cracked Pipe Subjected to Combined Mechanical and Thermal Loads Depending on Loading Conditions
Oh, Chang-Young ; Song, Tae-Kwang ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 609~617
DOI : 10.3795/KSME-A.2011.35.6.609
There is a trend towards the progressive use of higher operating temperatures and stresses to achieve improved efficiencies in power-generation equipment. It is important to perform the crack assessment under hightemperature and high-pressure conditions. The C(t)-integral is a key parameter in crack assessment for transient creep states. The estimation of the C(t)-integral is complex when considering the mechanical and thermal loads simultaneously. In this paper, we study estimation of C(t)-integral under combined mechanical and thermal load depending on loading conditions.
A Study of Fiber-Reinforced Material Models for the Mechanical Characteristics of Human Annulus Fibrosus
Lim, Jun-Taek ; Choi, Deok-Kee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 619~628
DOI : 10.3795/KSME-A.2011.35.6.619
Human soft tissues, including muscles, ligaments, skin, and blood vessels, are an interesting subject because damage to them can be observed in everyday life. Besides the lack of available experimental data and the large deformation upon loading, the anisotropic and compressible nature of annulus fibrosus makes it more difficult to find a simple material model. A fiber-reinforced hyperelastic material model is used to determine the stress-strain curves upon uniaxial loading. The energy potential function for annulus fibrosus is composed of three different parts: matrix, fibers, and matrix-fiber interaction, which accounts for the angles between two families of fibers. In this paper, two different types of energy potential function for the matrix are considered, and are inserted into the fiber-reinforced model. The calculated results are compared with the Neo-Hookean model and experimental data, and reasonable agreement is observed overall.
Study on a System Reliability Calculation Method Using Failure Enumeration of Reliability Path
Lee, Jang-Il ; Park, Kee-Jun ; Chun, Hwan-Kyu ; Jeong, Choong-Min ; Shin, Dong-Jun ; Suh, Myung-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 629~633
DOI : 10.3795/KSME-A.2011.35.6.629
Recently, systems such as aircraft, trains and ships have become larger more complex. Therefore, the reliability calculation of these systems is more difficult. This paper presents a reliability calculation algorithm for a complex system with a solution that is difficult to analyze. When the system has a very complex structure, it is very difficult to find an analytical solution. In this case, we can assess system reliability using the failure enumeration method of the reliability path. In this research, we represent the reliability block diagram by an adjacent matrix and define the reliability path. We can find any system status by the failure enumeration of the reliability path, and thus we can calculate any kind of system reliability through this process. This result can be applied to RCM (Reliability-Centered Maintenance) and reliability information-management systems, in which the system reliability is composed of the reliabilities of individual parts.
Effect of Groove Shape on Residual Stress Distribution in Narrow Gap Welds
Soh, Na-Hyun ; Yang, Jun-Seok ; Pyo, Chang-Ryul ; Huh, Nam-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 635~642
DOI : 10.3795/KSME-A.2011.35.6.635
It is well known that conventional welding techniques can result in welding defects due to the large groove angle of the weld. In this context, the narrow gap welding (NGW) technique is applied in the nuclear industry because of its inherent merits such as the reduction in welding time and the shrinkage of the weld, and the small deformation of the weld resulting from the small groove angle and welding bead width. In this paper, the distribution of welding residual stress and deformation behavior of the ER308L weld due to NGW are predicted through nonlinear two-dimensional finite element analysis, in which the actual NGW process is simulated in detail. In particular, the effects of the shape of weld, i.e., the width of the weld and the shape of the welding groove, on the residual stress are investigated. The present results can be used to assess the integrity of defective nuclear components and to improve the welding process.
Seat Tightness of Flexible Metal Seal of Butterfly Valve at Cryogenic Temperatures
Ahn, Jun-Tae ; Lee, Kyung-Chul ; Lee, Yong-Bum ; Han, Seung-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 643~649
DOI : 10.3795/KSME-A.2011.35.6.643
For the development of butterfly valves used in liquefied natural gas (LNG) vessels, the seat tightness is one of the important factors to be taken into account in the valve-design process. An O-ring-type metal seal with a retaining ring showing good seat tightness at cryogenic temperatures has been widely used, despite the high manufacturing costs involved. As an alternative, a flexible solid metal seal offers not only sufficient tightness of the butterfly valve, meeting specification requirements, but also relatively low manufacturing costs. In this study, a design criterion to ensure the seat tightness of the butterfly valve using the flexible solid metal seal is proposed. The contact pressure can be calculated by the simulation of the frictional contact behavior between the surface of the metal seal and the valve disc. The geometry of the flexible solid metal seal is determined so that it satisfies the design criterion for sufficient seat tightness, and is verified by experiments according to BS6755 and BS6364.
Leak-Before-Break (LBB) Assessment Method Considering Crack Nonlinearity Using Effective Elastic Modulus and Material Nonlinearity
Kim, Maan-Won ; Kim, Sung-Hwan ; Lee, Eui-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 651~659
DOI : 10.3795/KSME-A.2011.35.6.651
With the increase in the thermal power output of recently developed nuclear power plants, the applied forces and moments are increased in some piping systems, so that the leak-before-break (LBB) application criteria would not be satisfied in those pipes. In this paper, we present a method for obtaining the additive LBB margin in the pipes by considering the nonlinearity of the crack and material properties. Finite element analysis and the moment-rotation equation of beam theory were used to calculate the nonlinearity of the crack and material properties. Moreover crack stability analysis was performed using the method proposed in this study. The LBB margin was increased effectively through consideration of the nonlinearity of the crack and material properties in the pipe.
Touch-Trigger Probe Error Compensation in a Machining Center
Lee, Chan-Ho ; Lee, Eung-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 661~667
DOI : 10.3795/KSME-A.2011.35.6.661
Kinematic contact trigger probes are widely used for feature inspection and measurement on coordinate measurement machines (CMMs) and computer numerically controlled (CNC) machine tools. Recently, the probing accuracy has become one of the most important factors in the improvement of product quality, as the accuracy of such machining centers and measuring machines is increasing. Although high-accuracy probes using strain gauge can achieve this requirement, in this paper we study the universal economic kinematic contact probe to prove its probing mechanism and errors, and to try to make the best use of its performance. Stylus-ball-radius and center-alignment errors are proved, and the probing error mechanism on the 3D measuring coordinate is analyzed using numerical expressions. Macro algorithms are developed for the compensation of these errors, and actual tests and verifications are performed with a kinematic contact trigger probe and reference sphere on a CNC machine tool.
Design of Cam Contour for Constant Hangers
Lee, Gun-Myung ; Park, Mun-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 669~675
DOI : 10.3795/KSME-A.2011.35.6.669
A constant hanger is a device for supporting pipes in plants. It supplies a constant force to a supporting pipe even if the pipe moves because of thermal expansion. In this paper, we propose a method for designing the contour of a cam for a constant hanger. It has been shown that the contour of a cam must satisfy the geometrical relation of the cam, the force balance equation for the load tube, the relation between the side spring compression and the cam rotation angle, and the moment balance equation for the cam. A calculation procedure to solve these equations simultaneously is proposed, and a constant hanger is designed successfully.
A Study on Performance Optimization of a Hydraulic Breaker
Shin, Dae-Young ; Kwon, Ki-Beom ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 677~682
DOI : 10.3795/KSME-A.2011.35.6.677
In this study, a simulation model developed for a hydraulic breaker is verified through comparison of simulation results to the experimental results. For performance optimization, the design parameters are selected based on the physical parameters of the equipment for ease of modification. Also a factorial experiment and regression analysis were conducted to observe the effect of each parameter on the performance of the hydraulic breaker. As a result, a method for optimizing the performance of a hydraulic breaker is proposed.
Procedure and Method of Equipment Qualification for Solenoid-Operated Valves Used in Nuclear Power Plants
Lim, Byung-Ju ; Park, Chang-Dae ; Chung, Kyung-Yul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 683~691
DOI : 10.3795/KSME-A.2011.35.6.683
In order to develop technology for an equipment qualification (EQ) test, which is an important process in localizing solenoid-operated valves used in nuclear power plants, we analyzed related regulations, test procedures, conditions, equipment, and acceptance criteria. EQ regulations for the solenoid-operated valve are classified as law, guide, and standard, and are subdivided according to test specimens and contents. The EQ test is composed of functional, normal-, and accident- condition tests. The solenoid-operated valve is aged under normal and accident conditions, which are predicted in the design conditions of a nuclear power plant, and the performance of the valve is measured by a functional test. The test method and procedure analyzed in this paper might be very useful for manufacturers as well as EQ testers.
Optimal Design of a Mini-Loader Based on the Design of Experiments
Kwon, Ki-Beom ; Shin, Dea-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 35, issue 6, 2011, Pages 693~699
DOI : 10.3795/KSME-A.2011.35.6.693
In this study, a hydraulic system of a mini-loader is modeled, and the model is validated by comparing the simulation results to the experimental results. A load force acting on the structure of the mini-loader is obtained from the simulation of the hydraulic system, and the structural analysis via finite element method is performed using the obtained load force to evaluate the structural safety of the loader. For the mainframe that requires additional strengthening according to the structural analysis, the optimum design parameters are proposed using the design of experiments to improve strength without additional mass.