• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.05a
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• pp.12-14
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• 1998

• Tribology and Lubricants
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• v.37 no.5
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• pp.172-178
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• 2021

An injector is a mechanical device present inside the engine. Its main function is to supply an appropriate volume of fuel into the combustion chamber, which is directly related to the overall engine efficiency of a car. During the operation of an injector, a magnetic force lifts the parts of the injector from closed position to open position which generates a horizontal force on the needle. The horizontal force acts on a different position from that of the center of mass of the needle. Therefore, this causes eccentricity in the needle and the generation of a tilting motion during the lifting operation which can result in wear. However, appropriate selection of clearances for these parts can prevent wear. In this study, lubrication analysis is conducted to determine the optimum clearance of parts with sliding motion inside the injector. The height functions are derived considering the dynamic behavior and relative velocity of the parts. Using the derived height function, the pressure profiles are calculated for the lubricated surfaces from the Reynolds' equation. Subsequently, the fluid reaction forces are calculated. The equations of motions are applied to the fluid reaction forces and external forces are solved to calculate the minimum film thickness between each part with variation in the clearances. Finally, the optimum clearances are determined. The effect of the clearances on the behavior of the moving parts is presented and discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.42-49
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• 1995

In this study, the optimum structural modification of the L-type structure by shape changes is suggested. The vibration characteristics of L-type structure are analyzed by the sub-structure synthesis method, and the coordinte sensitivities of each sub-structure are calculated and the change quantities of the positions to be modified are suggested by using the coordinate sensitivities. The results obtained are as follows : 1. The sensitivities of the natural frequency could be calculated by the sensitivity analysis. 2. The change quantities of the position to be modified could be suggested by the optimum structural modification method. 3. The developed program could reduce the process and time of computation, since the sensitivity was directly calculated by differential method, not finite difference method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.101-107
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• 2005

The objective of this study is structural analysis and optimum shape of rope brake. The finite element model was implemented to compute the stress, strain and friction force for rope brake. The ANSYS code was used for this analysis. Structural analysis are effected by position and height of reinforcement figure. The structural safety was examined by an establishment angle of the rope brakes which made apply to housing of the most suitable shape. The optimum shape of the rope brake was decided after stress and strain results were compared and examined.

• Tribology and Lubricants
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• v.10 no.4
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• pp.33-42
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• 1994

An influence of inlet pressure on the performance of sector-shaped pad thrust bearings is investigated theoretically. The optimum conditions of film thickness or the optimum positions of pivot are found through the evaluation of load capacity for all available conditions of film thickness, under the operating conditions which the thermal and pad deformation effects can be neglected. The bearing performance including the inlet pressure effects is obtained for a wide operating ranges that inertia parameter(Re$^{*}$) is up to unity, and for the various cases of pad extent angle (number of pad) and the three cases of the angle between pads. The results show that the inlet pressure has a large influence on the performance of sector-shaped pad thrust bearings. In the design of sector-shaped pad bearings, due to the inlet pressure, the optimum number of pad is varied with the operating speed and the angle between pads, and the optimum position of pivot is located toward the leading edge along with the operating speed increases.

• 전기의세계
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• v.20 no.1
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• pp.9-18
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• 1971

The characteristics of optimum control for the second order P.W.M. sampled-data system with linear plants are investigated, with the development of method for finding the cannonical represetations for the initial states, as well as the optimality of modulator output for the P.W.M. system, which contains the electro-mechanical components, by dividing the phase plane into several regions, in which the position of the system in the phase plane are converted into the pulse polarity and pulse width.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.458-461
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• 2002

This study presents development of a machine for shrink wrapping of cans or drink bottles with thermoplastic films. The accurate position-control, the safety factor of chains, the reduction-ratio of the chain and gear, the appropriate heating temperature for banding vinyl are discussed for the optimum shrink wrapping M/C design.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.3
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• pp.284-292
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• 1997

This paper is concerned with position control of direct drive robots. The proposed algorithm consists of the feedback controller and neural networks. Mter the completion of learning, the output of the feedback controller is nearly equal to zero, and the neural networks play an important role in the control system. Therefore, the optimum retuning of control parameters is unnecessary. In other words, the proposed algorithm does not need any knowledge of the con¬trolled system in advance. The effectiveness of the proposed algorithm is demonstrated by the experiment on the position control of a parallelogram link-type direct drive robot.

• Design & Manufacturing
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• v.13 no.4
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• pp.34-39
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• 2019

In this paper, in order to improve the formability and quality of the injection molded parts in the molds for molding the motorcycle rear cowl injection molded parts with different volumes at the same time, the flow of the molded parts is changed through the injection molding CAE analysis by changing the gate position, runner size and position. It is to find the optimum gate position, the diameter of the runner and the position where the balance is equal. The molded article formed by the optimization resulted in the uniformity of the molten resin at the same time at the corner of the product, thereby maintaining the flow balance favorable for mass production at lower injection pressure.

• The Journal of the Korean dental association
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• v.51 no.11
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• pp.586-594
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• 2013

The critical factors affecting the esthetics of anterior implants can be summarized as following: 1) Correct positioning of implant fixture 2) Enough amount of alveolar bone 3) Optimum volume of soft tissue. The position of implant is probably the most important factor in obtaining esthetic treatment outcome. The 3-dimensional orientation of implant is determined by the position on the alveolar ridge and its direction. Clinicians often try to mimic natural teeth when fabricating restorations. During the course of esthetic diagnosis and treatment, however, one should not forget to consider the correlation between facial pattern, lips, gingiva, alveolar ridge, as well as remaining dentition. Since anterior region is biologically unfavorable when compared with posterior region, one minor discrepancy in positioning of implant can cause esthetically undesirable treatment outcome. If one understands the biological and prosthetic meaning of implant's 3-dimensional position, he or she can achieve superior esthetic outcome in anterior region.