• 전기학회논문지
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• 제64권1호
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• pp.72-77
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• 2015

When connecting 6 lead wires from stator windings to the terminals of 3 phase induction motors for Y or ${\triangle}$ connection, it is feared that the polarities of windings could be reversed each other if the wire tags are lost or erased, resulting in inadmissibly high current to motors in case of starting. To protect motors against such situations, some test procedures are necessary during wire connection which need to be easy ways to electricians without particular tools except a general multi-tester and with less time-consuming in the field. This study focuses on a test measure to satisfy these requirements which is able to provide them a convenient procedure for winding polarity discrimination considering the field condition. Here, the proposed measure utilizes the residual magnetism of the rotor and checks the indication of voltage or current at windings which are induced by the residual flux of rotor when rotating it by hands with 3 stator windings connected in the form of I connection. Principle characteristics and experiment results for this method are analyzed in the view of the effectiveness and applicability for the winding polarity discrimination.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.152-160
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• 2011

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) which is consisted of many motors in water pump, air blower, and hydrogen recycling pump as well as inverters for these motors is essential. Furthermore, there are also electric systems for entertainment, information, and vehicle control such as navigation, broadcasting, vehicle dynamic control systems, and so on. Since these systems are connected by high voltage or general cables, EMC (Electromagnetic compatibility) analysis for high voltage and general cable of FCEV is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields by high voltage and general cables for FCEVs is studied. From numerical analysis results, total time harmonic electromagnetic field strength from high voltage and general cables have difference of 13~16 dB due to ground effect by impedance matching. The EMI results of FECV at 10 m distance shows difference of 41 dB at 30 MHz and 54 dB at 230 MHz compared with only general cable routing.

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1137-1140
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• 2014

선박의 전동기에 고장이 발생하면 대개 육상에서 수리 후 본선에 다시 재설치 되고 있으나 연결 단자의 기호 표시가 지워지거나 분명치 않을 때는 결선과정에서 전동기 권선의 극성 구별이 어려워진다. 이로 인해 Y-${\delta}$ 기동의 전동기에서 한 권선의 극성을 반대로 잘못 연결하는 경우 전원 투입과 동시에 과다한 전류가 흐르면서 재차 2차 고장으로 이어질 위험이 있다. 이러한 문제와 관련하여 본 논문은 고정자의 1상 권선에 미소 직류전류를 흘릴 때 나머지 권선들에서 유도되는 과도 기전력의 특성을 토대로 아날로그 멀티테스터를 이용한 고정자 권선의 극성 판별법을 제시하고 관련 특성을 분석한다. 또한, 이 같은 방식을 실제 전동기에 적용하여 단계적인 측정과정을 통해 단자연결의 이상여부를 현장에서 용이하게 판별할 수 있는지를 확인해 보기로 한다.

• 전기학회논문지
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• 제62권12호
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• pp.1668-1677
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• 2013

This paper deals with the power loss and thermal characteristics of induction motor for machine tools according to the rated power and speed. To reduce the fabrication error by thermal strain in rotational machine tools, we calculated the power loss and thermal behavior of induction motors. Firstly, the inverse design of general induction motors for machine tool spindle has been performed. The inverse design results are compared with the torque-speed characteristic curve in motor's catalog. The power loss are calculated by finite element method(FEM) at rated condition. Secondary, the transient thermal characteristics of induction motors are calculated by equivalent thermal resistance model from Motor-CAD S/W. The inverse design, power loss and thermal behavior calculation for induction motors with various rated power and speed has been performed. Finally, to verify the design and calculation process of induction motor, we implemented the experimental set with 0.4kW 1710rpm class industrial induction motor model. The obtained thermal characteristics of experimental model confirmed that the design and power loss calculation processes are appropriate to the prediction of thermal strain in rotational machine tools.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2002년도 제23회 학술발표회 초록집
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• pp.35-35
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• 2002

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.486-493
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• 2017

Refineries and chemical plants with isolated power systems that have a limited power supply are more susceptible to voltage changes from disturbances compared to power systems connected with a power company. Furthermore, most loads in such cases are induction motor loads, and therefore, transient voltage characteristics when starting a high-capacity motor must be examined. In general, high-capacity motors are customized appropriately to the load performance curve by the manufacturer during the construction of an industrial plant. Subsequently, when complying with the voltage drop permitted by international standards during the design process, power supply equipment such as transformers and generators is overdesigned. Therefore, a novel analysis is necessary on standards for startup and constraint voltage drops, as well as on identifying the voltage drop limitations for starting high-capacity motors in refineries and chemical plants with isolated power systems. In this study, field tests on an industrial plant were conducted, and simulations modeled under conditions identical to those of the field test system were performed using the general-purpose program ETAP in order to compare the results.

• 소성∙가공
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• 제13권1호
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• pp.15-20
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• 2004

본 연구에서는 자동차용 판재 성형시 발생하는 스프링백을 정확히 예측하기 위하여, 수정된Chaboche형에 기초한 혼합형 등방-이동경화규칙이 개발되었다. 또한 판재의 이방성을 위하여 최근 개발된 Barlat의 YId2000-24 비이차 비이방성 항복 함수가 이용되었다. 단순인장실험과 인장/압축(압축/인장) 실험에 의하여 Bauschinger 및 transient 거동과 비이방성이 측정되었으며, 유한요소해석에 의한 구성방정식의 검증을 위해 실제 자동차 부품을 부분 변형시킨 double S-rail이 제작되었다. 수정된 Chaboche 형 조성방정식과 비등방 항복함수를 적용한 유한요소에 의한 수치해석의 결과는 굽힘에 의한 스프링백과 비틀림에 있어서 실험과 잘 일치함을 알 수 있었다.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.203-209
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• 2014

The rear center-hinge bracket is designed for supporting and folding the rear-seat backrest. This bracket needs to be strong enough to be able to rigidly hold the rear-seat backrest and to withstand luggage loads from the car trunk that are generated when a vehicle is driving on the roads. Particularly, current accident studies report that many serious occupant injuries occurred when the rear-seat back easily folded inward toward the car interior, driven by the luggage loads in the trunk. Given this fact, the robust design of the rear center-hinge bracket that mainly supports the rear backrest has become more important for providing customer safety and preventing high warranty and durability problems. However, none of the studies have emphasized its significant role and considered its robust optimization. Therefore, this paper presents how the hinge-bracket design is optimized based on an application of the finite-element method coupled with the parameter design using Taguchi's design experiment. Finally, Taguchi method's application optimizes a robust center-hinge bracket that shows more rigid performance although it has lighter weight and thinner thickness.

• 자동차안전학회지
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• 제13권1호
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• pp.6-13
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• 2021

This paper presents yaw moment control for modification of steering characteristic in rear-driven vehicle with front in-wheel motors (IWMs). The proposed control algorithm is designed to modify yaw rate response of the test vehicle. General approach for modification of steering characteristic is to define the desired yaw rate and track the yaw rate. This yaw rate tracking method can cause the chattering problem because of the IWM actuator response. Large overshoot and settling time in IWM torque response can amplify the oscillation in control input and yaw rate. To resolve these problems, open-loop IWM controller for cornering agility was designed to modify the understeer gradient of the vehicle. The proposed algorithm has been investigated via the computer simulations and the vehicle tests. The performance evaluation has been conducted on dry asphalt using E-segment test vehicle. The performance of the proposed algorithm has been compared to general yaw rate tracking algorithm in the vehicle tests. It has been shown that the proposed control law improved the cornering agility without chattering problem.