• Proceedings of the KSME Conference
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• 2004.11a
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• pp.142-147
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• 2004

In this paper, a new procedure is proposed to accomplish the primary plus secondary stress(P+Q) at the 'structural element' instead of 'transition element'. For the P+Q evaluation, the calculated stresses by FEA are linearized along a stress classification line to extract the stress category, then the stress intensity is calculated to compare with the $3S_{m}$ limit. Also, in this paper, the 'design by analysis' criteria, adopted fundamental concepts and a new approach to calculate $K_{e}$ factors are explained. The new procedure combined with 3-D FEA has been applied to motor operated valve in order to the over conservatism and the rack of margin. The evaluation results show a good applicability and can be utilized for fatigue life evaluation by using P+Q.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.113-119
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• 2014

For the robust design of Motor Driven Power Steering (MDPS) systems, it is important to consider energy efficiency from every aspect such as system configuration and current flow, etc. If design optimization is not considered, it has many problems on a vehicle. For example, when evaluating steering test, particularly the Catch-up test which turning the steering wheel left or right quickly, steering effort should be increased rapidly. Also a vehicle might have poor fuel efficiency. In this study, it is calculated energy consumption for each component of the steering system and analyzed factors of energy consumption. As a result, this paper redefines a method to estimate steering input torque using characteristics of vehicle electric components and then conducts an analysis of contribution for the Catch-up.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.909-911
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• 2003

The almost pole transformers are constructed with tank, cover, clamp etc., that contains the insulation oil, core, coil, terminals, bus and the other accessories. If some fault current will be flown by some trouble or accident, interior pressure of the transformer shall be very quickly rise, and mechanical components or insulation oil from the transformer enclosure shall be propelled or dropped from the tank. For the prevention of the above accident, recently the pole transformers should be done 'the Design Tests for Fault Current Capability' according to ANSI C57.12.20(1997) There are two tests method in this standard, Test Number I with a high current arcing fault, without internal fusible elements, shall be conducted on rack enclosure with its minimum designed air space. Test Number II with an internal fusible element, shall be conducted on each enclosure diameter utilizing the internal fusible elements. KEPCO recently request to be done the 'Design Tests for Fault Current Capability' for pole transformers according to KEPCO's standard ES141-$533{\sim}545$, PS141-$482{\sim}518$ and RS141-$611{\sim}628$ that is same with Test Number I of ANSI C57.12.20.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.211-212
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• 2008

정보가전기기들의 대형화 제품개발 및 생산에 따른 전력소모가 극대화 되어있는 현실에 에너지소비를 줄이기위한 많은 연구들이 진행되고 있다. 그 중 LCD TV 분야는 전체 전력소비의 약 70% 이상이 Back-light에 의해 소비되므로 효율석인 Back-light 설계에 관한 관심이 증가하고 있다. 근래에 전통적인 CCFL 방식의 flack-light 구조에서 LED Back-light으로 점차 대체되어가고 있으며, 이러한 변화는 앞으로도 지속적으로 증가하기라 예상된다. 따라서, LED Hack-light의 효율적인 선력관기는 산업적 측면에서도 매우 주요한 부분이라 할 수 있다. 본 논문은 대형 TV의 에너지효율을 높이기위한 LED Rack-light 구성에 관한 요소들을 관계를 기술하고, 특히 Back-light 밝기제거를 통한 효율적인 전력관리를 실현위한 다채널 구동제어신호 생성에 관해 설명한다.

• ETRI Journal
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• v.10 no.3
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• pp.157-164
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• 1988

In proportion to the increased density in electronic packaging from chip to system levels of telecommunication system, thermal management is becoming a vital subject to save the cost of the electronic product and to maintain high reliability. The key to the successful application of the thermal management technique is the capability to predict the equipment thermal behaviors in early stage of system development and product design. This paper describes the application of correlations of natural convection to TDX-10 digital switching system, which has been under the 5 year development project since 1987, in order to predict equipment temperature and thermal behaviors whihin a rack.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.4
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• pp.206-215
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• 2016

Delta parallel robots are now widely used for high-speed applications. However, typical Delta robots, such as ABB Flexpicker suffer from rotating axis with passive prismatic joint subjected to critical speed and so requiring careful maintenance. In this paper, a novel 4-DOF high-speed parallel robot with four legs is presented, which consists of three legs with 90 degree arrangement for translational motions and one remaining leg with rack & pinion gears for rotational motion. The inverse kinematics, velocity, acceleration, statics, and inverse dynamics have been analyzed. From the workspace analysis and inverse dynamics simulation for 0.43 sec cycle time, the 4-axis parallel robot prototype with 12kg payload has been designed. In the future research, computed torque control methods will be developed for the prototype.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.313-317
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• 2005

Precision motor dynamometer is requiring for nano positioning control performance recently. Particularly, linear motor is using rapidly and the dynamometer needs is increasing. In this study, a precision control dynamometer is designed using MR (Magnetic Rheological) damper. The ultra precision motor system including the driver and controller is tested using the MR damper dynamometer. This dynamometer is able to measure torque for rotary motor or traction force with linear positioning accuracy for linear motor system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2451-2460
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• 2000

In order to minimize straightness error of deflected shaft, a geometric adaptive straightness controller system is studied. A multi-step straightening and a three-point bending process have been developed for the geometric adaptive straightness controller. Load-deflection relationship, on-line identification of variations of material properties, on-line springback prediction, and real-time hydraulic control methodology are studied for the three-point bending process. By deflection pattern analysis and fuzzy self-learning method in the multi-step straightening process, a straightening point and direction, desired permanent deflection and supporting condition are determined. An automatic straightening machine has been fabricated for rack bars by using the developed ideas. Validity of the proposed system is verified through experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.553-561
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• 2009

This paper presents development of ROV-type underwater robot capable of cleaning ship hull in automatic mode. The purpose of developing this robot is for underwater cleaning to secure the safety of divers who inspect and clean the ship hull. The robot consists of the cleaning system with rotating brush mechanism, a car-like driving mechanism, inspection system using video, and overall control system for underwater communication and operation. In this paper, we present overall design process of the cleaning system and operating system and technical contents of the overall control system for the underwater cleaning robot.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.2
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• pp.194-198
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• 2014

In recent years, RGM(roller gear mechanism) systems, wherein one of the gears of a meshing gear pair is replaced with pins or rollers, have been reintroduced, which is a consequence of, and therefore a reflection of, the rapid advances made in manufacturing technology. Three RTG(roller track gear) systems for arbitrary path transportation (e.g., L-, O-, U-, and S-shaped tracks) were constructed using two out of three RGM systems, namely, the CRP(cam rack pinion), CRG(cam ring gear), and RPG(roller pinion gear) systems, and are introduced in this paper. We also present three ways to prevent the intersection and non-contact phenomena at the teeth in the vicinity of the conversion point between two joined RGM systems.