• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.484-490
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• 2000

The freight wagon with weld fabricated 1-piece bogies, which was developed to increase operating speed, reveals its difficulties in maintenance. The weld-fabricated bogies were composed of two-stage coil spring and dry friction damping mechanism. The inborn wear parts and rather complicated structure mattes bogie maintenance difficult. In order to relieve this difficulties, the application of maintenance free rubber suspension is proposed by bogie maunfacturer, Taeyang Precision Limited. This study was conducted to determine design parameters of proposed rubber suspension by means of vehicle dynamic simulation and parametric study. The target critical speed of bogie was set over 150km/h for the preparation of further speed-up of freight wagon.

• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.383-387
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• 2010

The stereoscopic three-dimensional (3D) display provides a 3D image by inducing binocular disparity for the observers who wear special glasses. With the rapid progress in flat panel display technologies, the stereoscopic 3D display is becoming a new benefit-model of the current display industry, and several kinds of commercial stereoscopic 3D products have been released and are attracting people. Nowadays, the motion picture quality of the 3D image becomes as important as resolution or luminance since most of the commercial 3D products are 3D televisions or 3D monitors which are required to display a clear motion 3D image. In this paper, an analysis and simulation of the motion picture quality of stereoscopic 3D image is proposed, and a comparison of the motion picture performance among the current stereoscopic 3D technologies is also provided.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.251-256
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• 1999

"Ploughing" on the flank face of the tool in the metal cutting process is due to the tool in the metal cutting process is due to the finite edge radius of the tool and due to the development of flank wear. Because of the high stresses near the cutting edge, elastic-plastic deformation would be caused between the tool and the machined surface over a small area of the tool flank. The deformation would affect the roughness of the machined surface. Recently, some attempts have been made to predict the surface roughness, but elastic-plastic effect due to ploughing in the cutting process has not been considered. The research has analyzed mechanism of the ploughing of the cutting process using contact mechanics. Tool and workpiece material properties have been taken into account in the prediction of the surface roughness. The surface roughness has been simulated by the surface-shaping system. The results between experiment and simulation have been compared and analyzed. analyzed.

• Geomechanics and Engineering
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• 제20권5호
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• pp.421-432
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• 2020

Cutting of rocks is very common encountered in tunneling and mining during underground excavations. A deep understanding of rock-tool interaction can promote industrial applications significantly. In this paper, a distinct element method based approach, PFC^3D, is adopted to simulate the rock cutting under different operation conditions (cutting velocity, depth of cut and rake angle) and with various tool geometries (tip angle, tip wear and tip shape). Simulation results showed that the cutting force and accumulated number of cracks increase with increasing cutting velocity, cut depth, tip angle and pick abrasion. The number of cracks and cutting force decrease with increasing negative rake angle and increase with increasing positive rake angle. The numerical approach can offer a better insight into the rock-tool interaction during the rock cutting process. The proposed numerical method can be used to assess the rock cuttability, to estimate the cutting performance, and to design the cutter head.

• 한국기계가공학회지
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• 제11권2호
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• pp.7-12
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• 2012

In order to cope with the requirements of smaller patterns, larger surfaces and lower costs in the fields of displays, optics and energy, greater attentions are now being paid to the development of micro-pattern machining technology. Compared with flat moulds, large drums with micro patterns (roll moulds) have the advantages of short delivery, ease of manufacturing larger surfaces, and continuous moulding. This paper introduced the machining process technology of the roll moulds for display industry. The environmental effects were discussed and the importance of temperature maintenance was experimentally emphasized. The real time monitoring system for micro machining was introduced. A commercial solution was used to simulate the micro grooving and a deformation model of micro machined pattern was finally introduced.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.184-193
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• 2006

Rotation of intake and exhaust valves are very closely related to the long term durability of automotive engines. If the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. A principle of valve rotation mechanism was presumed based on some findings from experiments, and computer programs were developed to simulate the valve rotation phenomena. In this study we investigated the valve rotation mechanism by using the computer simulation models.

• 대한기계학회논문집
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• 제18권11호
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• pp.2967-2972
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• 1994

The multiple character of the contact interaction and the collective behavior of elementary microcontacts play a significant role in all the processes occurring in the surface layers, including the failure due to friction and wear. The array of metal spheres compressed between flat plates has been used for simulation of the contact behavior of multiple contact of solids under normal loading. An experimental design has been made providing regular array of the spheres at the same size with different spatial order. Measurement of electrial contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spots number and array on conductivity of contact has been evaluated.

• 유공압시스템학회논문집
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• 제3권1호
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• pp.7-14
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• 2006

In this paper, an in-process diagnosis method for performance of position control servo system was studied, which was based upon null bias, slew-rate ratio and delay time measurement. Slew-rate ratio and delay time were analyzed by theoretical analysis, computer simulation and experiment. As a result of these analysis, when spool of servovalve was weared, slew-rate ratio was decreased and delay time was increased.

• 복식문화연구
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• 제7권1호
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• pp.117-127
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• 1999

Clothes are a kind of silent language that tells someone who has in wear and has great influence on person perception and impression formation. Present paper aims, therefore, to investigate the tendency of its study to offer information that my assist future studies. Doctorial dissertations, master\`s theses and journal articles related with clothing and textiles in domestic are categorized according to period and subject. Analysed results are as follows: First, as for the periodic vicissitude, the number of study on impression formation was before 1990, but tend to increase in 1990\`s. Second, as for the subject, while the studies focused on impression formation wearer on the first half of 1990\`s, they were segmented and presented wearer\`s form and appearance in detail ; computer simulation was also made use of in various papers. In conclusion, impression formation seems to become a rather important subject for further study.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제5권1호
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• pp.46-52
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• 2002

A robust nonlinear observer, utilizing the sliding mode concept, is developed for the dynamic positioning of ships. The observer provides the estimates of linear velocities of the ship and bias from slowly varying environmental loads. It also filters out wave frequency motion to avoid wear of actuators and excessive fuel consumption. The main advantage of the proposed observer is in its robustness. Especially, the observer structure with a saturation function makes the proposed observer robust against neglected nonlinearties, disturbances and uncertainties. Since the mathematical model of DP ships is difficult to obtain and includes uncertainties and disturbances, it is very important for the observer to be robust. A nonlinear output feedback controller is derives based on the developed observer using the observer backstepping technique, and the global stability of the observer and control law is shown by Lyapunov stability theory.. A set of simulation was carried out to investigate the performance of the proposed observer for dynamic positioning of ships.