• Journal of Electrical Engineering and Technology
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• 제2권2호
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• pp.241-248
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• 2007

The accuracy of all the schemes that belong to vector controlled induction machine drives is strongly affected by parameter variations. The aim of this paper is to examine iron losses and magnetic saturation effect in sensorless vector control of induction machines. At first, an approach to induction machine modelling and vector control scheme, which account for both iron loss and saturation, is presented. Then, a model reference adaptive system (MRAS) based speed estimator is developed. The speed estimation is modified in such a way that iron losses and the variation in the saturation level are compensated. Thus by substituting an artificial neural network flux estimator into the MRAS speed estimator. Experimental results are presented to verify the effectiveness of the proposed approach.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1441-1447
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• 2008

This research studies the effects of community noise around railway, noise from the inside/outside noise of the High-Speed EMU. First study part of this year is research of the noise source. The modeling methodology for prediction of noise level including the frequency property, velocity dependence, sound pressure of noise source is investigate. Second part is research on the sound transmission loss. An exclusive program which could analyze the sound transmission loss of the floor, the sides(mirror), insulator in High-Speed EMU has to be developed. Third part is research on the train inside/outside and Prediction for community Noise. In order to predict the noise when the High-Speed EMU is traveling at the outside and along tunnels, the result of the research can be derived by evaluating the effect of the noise on the upper/middle parts of the carriage and on the railroad way round about with using the program.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.155-158
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• 1999

In the high speed range for Vector control of Synchronous Reluctance Motor, the effect of iron loss and the cross-coupling of dq axis currents is dependent on the increase of the operating frequency can not be negligible. In this paper, we propose a decupling Vector control of dq axis current that the effect of iron loss is eliminated, and confirm that through simulation results.

• 전기학회논문지
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• 제64권6호
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• pp.954-959
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• 2015

In this paper, 110kW high output density, high efficiency Permanent Magnet Synchronous Motor which can be applied on tram’s traction system is introduced, along with its output and loss characteristics. The motor model is 2pole 18slot model and its size has been reduced through the high speed for high output density. Especially, structure and retainer sleeve structure is applied to its structure, which is also appropriate for high speed rotation. This kind of structure has eddy current loss problem on the surface of rotor, which must be reduced for high output density design. This study has designed the most optimized additional design parameter in order to improve the output characteristics and efficiency of previous produced 2pole 18 slot 110kW motor model and how the width of airgap affects from the loss perspective is mainly analyzed. Finally, the analysis on the extent of the efficiency improvement effect compared to the previous model has performed through electromagnetic FEM analysis. The influence of airgap flux density distribution has also been thoroughly examined.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.128-135
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• 1998

돌극형 동기 릴럭턴스 전동기의 고속회전 영역에서, 철손의 영향은 무시할 수 없게 된다. 본 논문에서는 돌 극형 동기 릴럭턴스 전동기에 대하여 고정자 철손이 고정자 내의 둥가 와전류에 의해서 발생한다는 가정 하에서, 둥가 인덕턴스에 직렬로 등가 철손저항이 삽입된 모델을 이용하여 철손을 고려한 전압방정식을 유도하였다. 또, 동작 주파수의 증가에 따른 철손의 변동은 벡터제어계의 제어성능을 악화시키고,d 축과 q 축의 쇄교자속에 서로 간섭하여 벡터제어의 적용을 어렵게 한다. 따라서, d 축과 q 축을 비간섭화 하여 철손저항의 영향을 제거해서 비간섭 토크제어가 가능한 벡터제어법올 제안하였으며, 시뮬레이션올 통하여 이를 확인하였다.

• 열처리공학회지
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• 제11권3호
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• pp.159-167
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• 1998

In this study, friction-wear test was carried out on the carburized layer depth of a mechanical structure steel SNCM carburized with RX and LPG for 7hrs at $930^{\circ}C$ and also the wear properties of wear loss, wear rate, coefficient of friction, friction force and friction temperature were investigated. The wear properties for carburized layer of SNCM were tested on dry condition at the room temperature by the thrust load of 49~245N range at sliding speed of 0.2m/sec and the sliding speed of 0.2~1.0m/sec range at thrust load of 98N. Wear loss on the depth of carburizing layer was increased with increasing of thrust load and sliding speed, and with decreasing of hardness. The condition of worn surfaces were showed mild wear at less than the thrust load of 98N and sliding speed of 0.6m/sec but were showed severe wear at more than 98N and 0.6m/sec. The friction load and temperature were increased with increasing of thrust load but with increasing sliding speed was appeared minimum at 0.6m/sec. With increasing thrust load the wear rate was increased and the coefficient of friction was decreased, but with increasing sliding speed the wear rate and the coefficient of friction were decreased in 0.2~0.6m/sec and increased in 0.6~1.0m/sec, therefore 0.6m/sec in this testing is a transition velocity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.565-568
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• 2002

A lot of rotating machines are being used in the industrial world and electric motor and generator take the most part of it. When it comes to the electric motor and generator, we can not help thinking about the eddy current because it brings a loss of electric and can be a important reason of the heat generation. To attenuate eddy current. laminated silicon steel sheets are being used in general. Especially, laminated rotor is being used for rotating part of the electric motor and generator and it decreases electrical loss and heat generation but we can be faced with another problem. In general, most of the motor and generator can be normally operated under 3600rpm because they are designed to have the first critical speed more than that speed. But nowadays, they should be operated more than the first critical speed as usual with the trend of high speed. large scale and high precision in industrial world. The critical speed can be determined from the inertia and stiffness for the rotor and bearing of rotating systems. The laminated rotor stiffness can be hardly determined because it can be derived a lot factors for instance rotor material and shape. lamination material and shape. insulation material. lamination force and so on. In this paper, the change of the natural frequency of the motor was examined with the change of the lamination force as an experimental method.

• 한국의류학회지
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• 제30권4호
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• pp.607-614
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• 2006

This study was carried out to suggest the optimal spinning process condition which provides a proper range of tenacity and biodegradability as textile fibers. The effects of the melt spinning speed and heat treatment on the mechanical property and biodegradability of polylactic acid fiber were investigated. Polylactic acid(PLA) was spun in a high spinning speed of $2000{\sim}4000m/min$. Each specimen was heat-treated at $100^{\circ}C$ during 30min. Mechanical properties such as breaking stress and the degree of crystallinity were evaluated using WAXS. Biodegradability was estimated from the decrease of breaking stress, weight loss, and the degree of crystallinity after soil burial. Experimental results revealed that heat treated specimens showed higher breaking stress than untreated specimens, but the increase was not so high as was expected from the remarkable change of crystallinity by heat treatment. It was concluded that breaking stress was more influenced by spinning speed than heat treatment. In the soil burial test, however biodegradability calculated from weight loss was more influenced by heat treatment than spinning speed.

• 한국소음진동공학회논문집
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• 제13권6호
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• pp.474-483
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• 2003

In this study, the dynamic characteristics of a catenary system and pantograph supplying electrical power to high-speed trains are investigated. One of the most important issues accompanied by increasing the speed of high-speed rail is stabilization of current collection. To stabilize current collection, it is necessary the contact force between the catenary and the pantograph to be kept continuous without loss of contact. The analytical model of a catenary and a pantograph is constructed to simulate the behavior of an actual system. The analysis of the catenary based on the Finite Element Method (FEM) is performed to develop a catenary model suitable for high speed operation. The reliability of the models is verified by the comparison of the excitation test with Fast Fourier Transform (FFT) data of the actual system. The static deflection of the catenary, stiffness variation in contact lines, dynamic response of the catenary undergoing constant moving load, contact force, and each state of the pantograph model were calculated. It is confirmed that a catenary and pantograph model are necessary for studying the dynamic behavior of the pantograph system.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2159-2164
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• 2002

This paper reports on the effects of additional factors on the engine friction characteristics. The total friction loss of engine is composed of pumping and mechanical friction loss. The pumping loss was calculated from the cylinder pressure, and the mechanical friction loss was measured by strip-down method under the motoring condition. The various parameters were tested. The engine friction loss was much affected by oil and coolant temperature. The low viscosity oil was very effective to reduce the friction loss, and friction modifier was very useful to reduce the friction loss at lower engine speed. The engine friction loss was varied with engine running time because of surface roughness decreasing and oil degradation. To prevent oil-churning effect, it was very important to maintain the proper oil level. The presented results will be very useful to understand friction characteristics of engine.