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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 39, Issue 12 - Dec 2015
Volume 39, Issue 11 - Nov 2015
Volume 39, Issue 10 - Oct 2015
Volume 39, Issue 9 - Sep 2015
Volume 39, Issue 8 - Aug 2015
Volume 39, Issue 7 - Jul 2015
Volume 39, Issue 6 - Jun 2015
Volume 39, Issue 5 - May 2015
Volume 39, Issue 4 - Apr 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
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The Design and Performance Evaluation of a Parallelogram Type Magnetic Spring Suspension for Commercial Vehicle Seat
Kwac, Lee Ku ; Kim, Hong Gun ; Shin, Hee Jae ; Jung, Young Bae ; Song, Jung Sang ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 353~360
DOI : 10.3795/KSME-A.2015.39.4.353
Commercial drivers feel tired more than the general public, because their driving times are long and they experience more idle vibration. In this study, we developed a nonlinear model of a magnetic, linear spring seat suspension to determine the optimal design to improve ride comfort. The resonant frequency for the optimal design of the suspension was found to be 3.5 Hz, and the stiffness was analyzed through displacement-load experiments. Additionally, the vibration transmissibility was analyzed by the suspension stiffness, and the existing coil spring type vibration transmissibility was found to be 0.99. A parallelogram type magnetic spring was determined to result in a better performance than the existing spring with a vibration transmissibility of 0.823.
Development of an Intrinsic Continuum Robot and Attitude Estimation of Its End-effector Based on a Kalman Filter
Kang, Chang Hyun ; Bae, Ji Hwan ; Kang, Bong Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 361~367
DOI : 10.3795/KSME-A.2015.39.4.361
This paper presents the design concept of an intrinsic continuum robot for safe man-machine interface and characteristic behaviors of its end-effector based on real experiments. Since pneumatic artificial muscles having similar antagonistic actuation to human muscles are used for main backbones of the proposed robot as well as in the role of the actuating devices, variable stiffness of robotic joints can be available in the actual environment. In order to solve the inherent shortcoming of an intrinsic continuum robot due to bending motion of the backbone materials, a Kalman filter scheme based on a triaxial accelerometer and a triaxial gyroscope was proposed to conduct an attitude estimation of the end-effector of the robot. The experimental results verified that the proposed method was effective in estimating the attitude of the end-effector of the intrinsic continuum robot.
Weight Function-based Sequential Maximin Distance Design to Enhance Accuracy and Robustness of Surrogate Model
Jang, Junyong ; Cho, Su-Gil ; Lee, Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 369~374
DOI : 10.3795/KSME-A.2015.39.4.369
In order to efficiently optimize the problem involving complex computer codes or computationally expensive simulation, surrogate models are widely used. Because their accuracy significantly depends on sample points, many experimental designs have been proposed. One approach is the sequential design of experiments that consider existing information of responses. In earlier research, the correlation coefficients of the kriging surrogate model are introduced as weight parameters to define the scaled distance between sample points. However, if existing information is incorrect or lacking, new sample points can be misleading. Thus, our goal in this paper is to propose a weight function derived from correlation coefficients to generate new points robustly. To verify the performance of the proposed method, several existing sequential design methods are compared for use as mathematical examples.
Evaluation of the Structural Safety of a Vessel with Different Material(Cr-13)-Supplemented Screw Thread
Choi, Yong Hoon ; Bae, Jun Ho ; Kim, Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 375~382
DOI : 10.3795/KSME-A.2015.39.4.375
The dome and neck part of a vessel is generally formed by a hot spinning process with a seamless tube. However, as studies on and design data from the hot spinning process are insufficient, this process has been performed based on trial and error and the experiences of field engineers. Changes in the inner diameter from the bottom to the top of the neck have occurred mainly because of the characteristics of the hot spinning process due to the high-speed rotation of the rollers. In this study, a theoretical and finite element analysis of the vessel is conducted with different material(Cr-13)-supplemented screw threads for tapping and to reduce shape errors. Based on the results, tne structural safety under the operating conditions is evaluated.
Effect of Loading Rate on the Deformation Behavior of SA508 Gr.1a Low Alloy Steel and TP316 Stainless Steel Pipe Materials at RT and 316℃
Kim, Jin Weon ; Choi, Myung Rak ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 383~390
DOI : 10.3795/KSME-A.2015.39.4.383
This study conducted tensile tests on SA508 Gr.1a low alloy steel and SA312 TP316 stainless steel piping materials under various strain rates at room temperature (RT) and
to investigate the effects of loading rate on the deformation behavior of nuclear piping materials. At RT, the deformation behavior for both pipe materials showed a typical loading rate dependence, i.e., the strength increased and the ductility decreased as the loading rate increased. At
, however, the strength and elongation of SA508 Gr.1a low alloy steel decreased as the loading rate increased, and its reduction of area non-linearly varied with the loading rate. For SA312 TP316 stainless steel, the strength, elongation, and reduction of area at
were almost the same regardless of the loading rate. At both temperatures, the strain hardening capacity was nearly independent of the loading rate for SA508 Gr.1a low alloy steel, while it decreased with increasing loading rate for SA312 TP316 stainless steel.
A Study on the Effect of Hot Lines and the Assembly of Flange for a Refrigerator to Reduce Dew Generation
Kim, Na Hyun ; Cho, Jong Rae ; Park, Sang Hu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 391~396
DOI : 10.3795/KSME-A.2015.39.4.391
When the temperature of a flange in a refrigerator is reduced to the dew point, condensation is generated on the flange. Generally, hot lines, having a temperature of
, are located near the flange to increase its surface temperature above the dew point. Hot lines are installed in close contact with the flange in order to increase the heat transfer from the hot lines to the flange surface. Through this work, the effects of the hot line shape and installation conditions, including a gap between the hot line and flange, and the function of a spacer in the inner case of the refrigerator were investigated. Additionally, an optimal shape of the inner case for easy assembling is proposed considering the contact between the hot line and flange.
Reliability Qualification Test of a Unmanned Control Robot System for an Excavator
Back, Seung Jun ; Son, Young Kap ; Kim, Jun Hee ; Lee, Jong Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 397~403
DOI : 10.3795/KSME-A.2015.39.4.397
This paper proposes the development of a method for assessing the system reliability of an unmanned control robot system for an excavator. It then shows the results of the reliability qualification test based on the proposed method. The robot system functions to ensure the safety of the workers who control excavators in dangerous working environments, and the system reliability was calculated by integrating the reliabilities of the system components. Thus, test equipment for the three key units of the robot system were constructed and used in accelerated life testing. From the life testing results, guaranteed mean time between failures for the chosen confidence level was estimated, and the reliability qualification testing method of the robot system using small sample sizes was proposed.
Development of a Short-term Failure Assessment of High Density Polyethylene Pipe Welds - Application of the Limit Load Analysis -
Ryu, Ho-Wan ; Han, Jae-Jun ; Kim, Yun-Jae ; Kim, Jong-Sung ; Kim, Jeong-Hyeon ; Jang, Chang-Heui ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 405~413
DOI : 10.3795/KSME-A.2015.39.4.405
In the US, the number of cases of subterranean water contamination from tritium leaking through a damaged buried nuclear power plant pipe continues to increase, and the degradation of the buried metal piping is emerging as a major issue. A pipe blocked from corrosion and/or degradation can lead to loss of cooling capacity in safety-related piping resulting in critical issues related to the safety and integrity of nuclear power plant operation. The ASME Boiler and Pressure Vessel Codes Committee (BPVC) has recently approved Code Case N-755 that describes the requirements for the use of polyethylene (PE) pipe for the construction of Section III, Division 1 Class 3 buried piping systems for service water applications in nuclear power plants. This paper contains tensile and slow crack growth (SCG) test results for high-density polyethylene (HDPE) pipe welds under the environmental conditions of a nuclear power plant. Based on these tests, the fracture surface of the PENT specimen was analyzed, and the fracture mechanisms of each fracture area were determined. Finally, by using 3D finite element analysis, limit loads of HDPE related to premature failure were verified.
A Study of the Vibration Characteristics of a Haptic Vibrator for Horizontal and Vertical Magnetization
Ko, Dong Shin ; Hur, Deog Jae ; Park, Tae Won ; Lee, Jai Hyuk ; Lee, Sung Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 415~421
DOI : 10.3795/KSME-A.2015.39.4.415
This paper describes the study of the design procedure for the step-by-step setup parameters and of the magnetizing method for performance and size reduction in the development of a haptic vibrator. The study of magnetization was accomplished by comparing the electromagnetic force in accordance with the horizontal and the vertical magnetization. The theoretical results indicated that the horizontal magnetization resulted in a better performance. The systematic design of a step-by-step procedure for establishing the design parameters was verified by testing the characteristics of the fabricated prototype product. The vibration response function analysis and electric field analysis were processed by decoupling of the analytical method, and these were determined to be in good agreement with the test results. The design parameters to contributing to the product reliability included the spring height, the welding position, and the coil position. The sensitivity of the electromagnetic field and the performance change were analyzed based on the design parameters. As a result, we proposed a design method to implement a reliability-based, high performance haptic vibrator.
Study of the Assembly of Indoor Air-conditioner Unit Using Tolerance Analysis
Kim, Cheulgon ; Hwang, Jihoon ; Seo, Hyeongjoon ; Mo, Jinyong ; Jung, Duhan ; Hong, Seokmoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 423~428
DOI : 10.3795/KSME-A.2015.39.4.423
To identify locations and causes of interference among parts of an indoor air-conditioning unit, a 3D tolerance analysis was performed and optimized with respect to assembly gaps and the tolerance of each part. The maximum value of the defect rate resulting from the tolerance analysis was found to be 72.6 at the assembly portion of the body and drain. The maximum displacement caused by the thermal deformation during a heating operation was calculated to be approximately 1 mm by using finite element analysis (FEA). Therefore, it is possible that an interference among the assembled parts occurs. The tolerance of the drain was modified by the results of the sensitivity analysis. As a result, the defect rate was greatly reduced to 0.03. Through the FEA results of the indoor air-conditioning unit, it was shown that the improved tolerance of the drain decreased the interference among the assembled parts even though thermal deformation occurs during operation.
Study on Deformation of Miniature Metal Bellows in Cryocooler Following Temperature Change of Internal Gas
Lee, Seung Ha ; Lee, Tae Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 429~435
DOI : 10.3795/KSME-A.2015.39.4.429
A bellows is an important temperature control component in a Joule-Thomson micro-cryocooler. It is designed using a very thin shell, and the inside of the bellows is filled with nitrogen gas. The bellows is made of a nickel-cobalt alloy that maintains its strength and elastic properties in a wide range of temperatures from cryogenic to
. The pressure of the gas and the volume within the bellows vary according to the temperature of the gas. As a result, the bellows contracts or expands in the axial direction like a spring. To explore this phenomenon, the deformation of the bellows and its internal volume must be calculated iteratively under a modified pressure until the state equation of the gas is satisfied at a given temperature. In this paper, the modified Benedict-Webb-Rubin state equation is adopted to describe the temperature-volume-pressure relations of the gas. Experiments were performed to validate the proposed method. The results of a numerical analysis and the experiments showed good agreement.
Design of a Perforated Panel for Transmission Noise Reduction
Park, Younghyo ; Bae, Jaehyeok ; Lee, Jin Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 437~445
DOI : 10.3795/KSME-A.2015.39.4.437
A design method for a perforated panel is suggested to reduce the level of incident noise without obstructing the flow of incoming fluid. The key idea was to insert an array of 1/4 wavelength tubes around the holes of the perforate panel. First, various case studies were performed for a unit model with only one hole. In order to avoid any increase in the panel thickness, the unit model was vertically divided into three layers, and only the middle layer was used as the design domain. The number and array of 1/4 wavelength tubes connected to the hole were optimized to obtain the widest effective frequency range in the transmission loss curve as possible. Then, the optimally designed unit model was converted to a periodic array in the perforated panel to achieve the design goals. Even if the target frequency and the target transmission loss were set to 1000 Hz and 10 dB, respectively, the suggested design method for the a perforated panel could achieve noise reduction for various target values.
A Study on the Structural Integrity Considering the Installation of a Micro-tube Heat Exchanger
Oh, Se Yun ; Kim, Tae Jin ; Cho, Jong Rae ; Jeong, Ho Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 39, issue 4, 2015, Pages 447~451
DOI : 10.3795/KSME-A.2015.39.4.447
The objective of this study is to predict the structural characteristics of a heat exchanger mounted on an aircraft engine using finite element analysis. The plastic fracture and life of the heat exchanger were estimated by a thermo-mechanical analysis. Tensile tests were conducted under high temperature conditions (700, 800, 900, 1000 K) using five specimens to obtain the mechanical properties of the Inconel 625 tubes. To assess the structural characteristics of the heat exchanger, the full and partial models were applied under the operating conditions given by the thermo-mechanical and inertial load. As a result, the case, tubesheet, flange, and mounting components have a reasonable safety margin to the allowable stress assuming a fatigue strength of Inconel 625 of 10000 cycles under 1000 K.