Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
Editor in Chief :
Volume & Issues
Volume 29, Issue 12 - Dec 2012
Volume 29, Issue 11 - Nov 2012
Volume 29, Issue 10 - Oct 2012
Volume 29, Issue 9 - Sep 2012
Volume 29, Issue 8 - Aug 2012
Volume 29, Issue 7 - Jul 2012
Volume 29, Issue 6 - Jun 2012
Volume 29, Issue 5 - May 2012
Volume 29, Issue 4 - Apr 2012
Volume 29, Issue 3 - Mar 2012
Volume 29, Issue 2 - Feb 2012
Volume 29, Issue 1 - Jan 2012
Selecting the target year
Analysis on the Vibration Characteristics of High Speed Train according to Track Structure
Hur, Hyun-Moo ; Park, Joon-Hyuk ; You, Won-Hee ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 593~599
DOI : 10.7736/KSPE.2012.29.6.593
To analyze the effect of the track structure on the running performance of the railway vehicle, we studied on the vibration and ride characteristics of the high speed train. As results, vibration and ride level of high speed train on the concrete bed track is more reduced than on the ballast bed track. Peak-peak value of carbody vibration on the concrete bed track at 300km/h is half of the peak-peak value of carbody vibration on the ballast bed track. Ride level on the concrete bed track at 300km/h is same level as that on the ballast bed track at 250km/h. Thus, Vibration and ride performance of the high speed train on the concrete bed track is greatly improved compared with that on the ballast bed track.
Damage Monitoring of Rolling Contact Fatigue in Wheel Specimen for High Speed Train Using Electro-Magnetic Sensor
Kwon, Seok-Jin ; Hwang, Ji-Sung ; Seo, Jung-Won ; Lee, Jin-Yi ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 600~606
DOI : 10.7736/KSPE.2012.29.6.600
Upon investigation of the damaged wheels for high speed train it was determined that the damage was caused by rolling contact fatigue during operation of train. The major problems that railway vehicle system using wheel-rail has to face during operation of railway vehicle are rolling contact fatigue, cracks in wheels, cracks in rails and wheel-rail profile wear. If these deficiencies are not controlled at early stages the huge economical problems due to unexpected maintenance cost in railway vehicle can be happened. Also, If the accurate knowledge of contact conditions between wheel and rail can be evaluated, the damage of wheel can be prevented and the maintenance operation can save money. This paper presents the applicability of electro-magnetic technique to the detection and sizing of defects in wheel. Under the condition of continuous rolling contact fatigue the damage of wheel has continuously monitored using the applied sensor. It was shown that the usefulness of the applied sensor was verified by twin disc test and the measured damaged sizes showed good agreement with the damaged sizes estimated by electro-magnetic technique.
Design of Wheel Profile to Reduce Wear of Railway Wheel
Choi, Ha-Young ; Lee, Dong-Hyong ; Song, Chang-Yong ; Lee, Jong-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 607~612
DOI : 10.7736/KSPE.2012.29.6.607
The wear problem of wheel flange occurs at sharp curves of rail. This paper proposes a procedure for optimum design of a wheel profile wherein flange wear is reduced by improving an interaction between wheel and rail. Application of optimization method to design problem mainly depends on characteristics of design space. This paper compared local optimization method with global optimization according to sensitivity value of objective function for design variables to find out which optimization method is appropriable to minimize wear of wheel flange. Wheel profile is created by a piecewise cubic Hermite interpolating polynomial and dynamic performances are analyzed by a railway dynamic analysis program, VAMPIRE. From the optimization results, it is verified that the global optimization method such as genetic algorithm is more suitable to wheel profile optimization than the local optimization of SQP (Sequential Quadratic Programming) in case of considering the lack of empirical knowledge for initial design value.
Effect of Rail Surface Damage on Contact Fatigue Life
Seo, Jung-Won ; Lee, Dong-Hyong ; Ham, Young-Sam ; Kwon, Sung-Tae ; Kwon, Seok-Jin ; Cho, Ha-Yong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 613~620
DOI : 10.7736/KSPE.2012.29.6.613
Rails are subjected to damage from rolling contact fatigue, which leads to defects such as cracks. Rolling contact fatigue damages on the surface of rail such as head check, squats are one of growing problems. Another form of rail surface damage, known as "Ballast imprint" has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. These defects are still one of the key reasons for rail maintenance and replacement. In this study, we have investigated whether the ballast imprint is an initiator of head check type cracks and effect of defect size using Finite element analysis. The FE analysis were used to investigate stresses and strains in subsurface of defects according to variation of defect size. Based on loading cycles obtained from FE analysis, fatigue analysis for each point was carried out.
New Lateral Force Measurement Method of the Wheel Plate for Railway Vehicles
Ham, Young-Sam ; Jun, Hyun-Kyu ; Seo, Jung-Won ; Lee, Dong-Hyong ; Kwon, Seok-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 621~625
DOI : 10.7736/KSPE.2012.29.6.621
Conventionally, to measure derailment coefficient of a railway wheel, strain gauges for lateral force measurement are attached to both side of the wheel. But narrow gap between railway wheel and traction motor makes it difficult to attache the strain gauges at the inner side of wheel. In this study, to overcome the hard accessibility to the strain gauge points by narrow gap, a new Wheatstone bridge connection method is presented by attaching all the strain gauges at the outer side of wheel with a new bridge connection. We evaluate the running safety of railway vehicles in accordance with railway safety regulations. The experimental results obtained shows higher sensitivity than conventional methods and the derailment coefficient measurement procedure becomes simpler.
Fatigue Life Evaluation of Motor Block Bracket Units for KTX-Sancheon Trains
Lee, Chan-Woo ; Lee, Dong-Hyong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 626~631
DOI : 10.7736/KSPE.2012.29.6.626
In this study, fatigue life of the motor block bracket units for KTX-Sancheon trains was assessed. Design evaluation for railway structures was performed based on the UIC 566 regulation, and test and evaluation of fatigue life in welded parts was performed in accordance with standard ERRI B 12/RP17 and ERRI B 12/RP60. The actual vehicle dynamic stress testing was executed in KTX-Sancheon service line with the service operating speed. The dynamic stress was measured with commercial data acquisition system (MGC plus). The cumulative damage was evaluated by applying standard BS 7608 - Class F and cycle counting was used rain-flow counting method. As a result, the motor block bracket units for KTX-Sancheon trains was designed to fit the regulation and the safety of fatigue life for 30 years, assuming that KTX-Sancheon trains travels 600,000km annually, were confirmed under current operating conditions.
A Study on Numerical Thermo-Mechanical Analysis for Aluminum 6061 Friction Stir Welding
Park, Chan-Woo ; Paeng, Jin-Gi ; Ok, Ju-Seon ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 632~639
DOI : 10.7736/KSPE.2012.29.6.632
A fully coupled thermo-mechanical model is adopted to study the temperature distribution and the material deformation in friction stir welding(FSW) process. Rotational speed is most important parameters in this research. Three dimension results under different process parameters were presented. Result indicate that the maximum temperature is lower than the melting point of the welding material. The higher temperature gradient occurs in the leading side of the workpiece. The maximum temperature can be increased with increasing the tool angular velocity, rpm in the current numerical modeling. In this research ABAQUS Ver.6.7 is to analyze a fully coupled thermo-mechanical model. ALE(Arbitrary Lagrangian-Eulerian) finite element formulation is used for the large deformation in FSW process and using the Mass scaling for the analysis time efficiency.
Laser Processing System Design of Ultrafast/High Precision/large Area
Lee, Jae-Hoon ; Yoon, Kwang-Ho ; Kim, Kyung-Han ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 640~647
DOI : 10.7736/KSPE.2012.29.6.640
Current electronic products are dominated by the laser processing and the application will be extended this time. Especially, demands for high precision laser processing with a large area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component and automobile industry. In this paper we designed an on-the-fly system for ultrafast/high precision/large area laser processing. In addition, we have developed the path algorithm for large area. Expansion of the area in which laser processing is an important factor to handle the ultrafast/wide area processing, it will require a processing path. Processing path is path of 2- axis stage and stage of change in velocity can be smooth as possible. We proposed a path of the user concept using NURBS(Non-Uniform Rational B-Spline)method. Through our experiment with the chopper, was to prove the continuity of edge parts. Through basic shape experiments, we proved that large area can be processed using laser. We developed a simulation tool using Visual C++.
Gate Locations Optimization of an Automotive Instrument Panel for Minimizing Cavity Pressure
Cho, Sung-Bin ; Park, Chang-Hyun ; Pyo, Byung-Gi ; Cho, Dong-Hoon ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 648~653
DOI : 10.7736/KSPE.2012.29.6.648
Cavity pressure, an important factor in injection molding process, should be minimized to enhance injection molding quality. In this study, we decided the locations of valve gates to minimize the maximum cavity pressure. To solve this problem, we integrated MAPS-3D (Mold Analysis and Plastic Solution-3Dimension), a commercial injection molding analysis CAE tool, using the file parsing method of PIAnO (Process Integration, Automation and Optimization) as a commercial process integration and design optimization tool. In order to reduce the computational time for obtaining the optimal design solution, we performed an approximate optimization using a meta-model that replaced expensive computer simulations. To generate the meta-model, computer simulations were performed at the design points selected using the optimal Latin hypercube design as an experimental design. Then, we used micro genetic algorithm equipped in PIAnO to obtain the optimal design solution. Using the proposed design approach, the maximum cavity pressure was reduced by 17.3% compared to the initial one, which clearly showed the validity of the proposed design approach.
Evaluation of Residual Strength Under Impact Damage in Woven CFRP Composites
Choi, Jung-Hun ; Kang, Min-Sung ; Koo, Jae-Mean ; Seok, Chang-Sung ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 654~663
DOI : 10.7736/KSPE.2012.29.6.654
Damage induced by low velocity impact loading in aircraft composite is the form of failure which is frequently occurred in aircraft. As the consequences of impact loading in composite laminates, matrix cracking, delamination and eventually fiber breakage for higher impact energies can be occurred. Even when no visible impact damage is observed, damage can exist inside of composite laminates and carrying load of the composite laminates is considerably reduced. The objective of this study is to evaluate and predict residual strength behavior of composite laminates by impact loading and for this, tensile test after impact was carried out on composite laminates made of woven CFRP.
A Study on the Vibration Reduction of Flue Gas Cooler Using Modal Analysis
Lee, Boo-Youn ; Kim, Won-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 664~670
DOI : 10.7736/KSPE.2012.29.6.664
In this work, vibration characteristics of a flue gas cooler(FGC) for a heavy oil upgrading are experimentally analyzed and an effective method is proposed to reduce the vibration level. Firstly, the vibration under the operation condition of the FGC is measured and analyzed to identify the generation phenomena of vibration. And the displacement of the outer wall of the FGC is also analyzed to identify dominant frequencies of vibration. Secondly, an effective design to reduce the vibration is suggested by using the modal analysis. Consequently an improved design of the FGC gas cooler, which has lower vibration level, is obtained and then verified though the analysis and test.
Estimation of Axial Displacement in High-speed Spindle Due to Rotational Speed
Bae, Gyu-Hyun ; Lee, Chan-Hong ; Hwang, Joo-Ho ; Hong, Seong-Wook ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 671~679
DOI : 10.7736/KSPE.2012.29.6.671
This paper presents an estimation procedure for axial displacement in spindle equipped with angular contact ball bearings due to rotational speed. High-speed spindle-bearing system experiences axial displacement due to thermal expansion and rotational speed-dependent characteristics of angular contact ball bearings. This paper deals with the axial displacement caused by the rotational speed-dependent effects such as centrifugal force and gyroscopic moments. To this end, a bearing dynamic model is established that includes all the static and dynamic properties of angular contact ball bearing. An analytical formula to calculate the axial displacement based on contact angles between ball and races is derived to discuss the physics regarding the axial displacement in spindle. The proposed dynamic model is compared with a reference and a commercial program. Numerical examples are presented to show the effects of centrifugal force and gyroscopic moment on the axial displacement. The proposed model is also validated with an experimental result.
Prediction of Stress Distribution in the Ceramic Femoral Head after Total Hip Replacement
Han, Sung-Min ; Chu, Jun-Uk ; Song, Kang-Il ; Park, Sung-Hee ; Choi, Jae-Bong ; Kim, Jung-Sung ; Suh, Jun-Kyo Francis ; Choi, Kui-Won ; Youn, In-Chan ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 680~685
DOI : 10.7736/KSPE.2012.29.6.680
Ceramic femoral heads are now widely used in Total Hip Replacement (THR). Due to their high biocompatibility and low ductility, ceramic femoral heads are considered to be suitable for young and active patients. However, as in testing the mechanical stability of the femoral head, the conventional proof test (standard ISO 7206-10) has its limit of showing axisymmetric stress distribution on the contact surface, while non-uniformed stress distribution is expected after THR. Since non-uniformed stress distribution can result in the increased probability of ceramic femoral head fracture, it is considerable to evaluate the stress distribution in vivo-like conditions. Therefore, this study simulated the ceramic femoral heads under in vivo-like conditions using finite element method. The maximum stress decreased when increasing the size of the femoral head and stress distribution was concentrated on superior contact surface of the taper region.
A Study on the Fabrication of Various 3D Microstructures using Polymer Deposition System
Kim, Jong-Young ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 686~692
DOI : 10.7736/KSPE.2012.29.6.686
Solid free-form fabrication (SFF) technology was developed to fabricate three-dimensional (3D) scaffolds for tissue engineering (TE) applications. In this study, we developed a polymer deposition system (PDS) and created 3D microstructures using a bioresorbable polycaprolactone (PCL) polymer. Fabrication of 3D scaffolds by PDS requires a combination of several devices, including a heating system, dispenser, and motion controller. The system can process a polymer with extremely high precision by using a 200
nozzle. Based on scanning electron microscope (SEM) images, both the line width and the piled line height were fine and uniform. Several 3D micro-structures, including the ANU pattern (a pattern named after Andong National University),
pattern square, frame, cylindrical, triangular, cross-shaped, and hexagon, have been fabricated using the polymer deposition system.
Development of the Furling Control Type Small Wind Turbine System
Choi, Young-Chul ; Kim, Chul-Ho ; Lee, Hyun-Chae ; Seo, Young-Taek ; Han, Young-Oun ; Song, Jung-Il ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 6, 2012, Pages 693~701
DOI : 10.7736/KSPE.2012.29.6.693
In this study, a small wind turbine airfoil specialized for national wind condition was designed in order to develop the furling control type HAWT. And then a flow analysis was carried out based on the blade drawing which was designed to characterize of the developed airfoil. The result of the flow analysis showed that the torque on the 3 blades was 180.23N.m. This is equivalent to an output power of 5.66kw and an output efficiency of 0.44. Then we produced and constructed a 3kW - furling control type HAWT by getting the system unit design technology such as the specialized furling control device. By operating this turbine, we could get 3kW of the rated power at a wind speed of 10.5m/s through the ability test. Cut-in wind speed was 2m/s, generator efficiency was 92% at the rated power output. Sound power level was 87.2dB(A). Also we observed that the output power was limited to 10.5m/s with furling system operation.