• Tribology and Lubricants
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• v.35 no.1
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• pp.44-51
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• 2019

The paper presents the rotordynamic performance measurements and model predictions of a fuel cell electric vehicle (FCEV) air compressor supported on gas foil bearings (GFBs). The rotor has an impeller on one end and a thrust runner on the other end. The front (impeller side) and rear (thrust side) gas foil journal bearings (GFJBs) are located between the impeller and thrust runner to support the radial loads, and a pair of gas foil thrust bearings are located on both sides of the thrust runner to support the axial loads. The test GFJBs have a partial arc shim foil installed between the top foil and bump strip layers to enhance hydrodynamic pressure generation. During the rotordynamic performance tests, two sets of orthogonally installed eddy-current displacement sensors measure the rotor radial motions at the rotor impeller and thrust ends. A series of speed-up and coast-down tests to 100k rpm demonstrates the dominant synchronous (1X) rotor responses to imbalance masses without noticeable subsynchronous motions, which indicates a rotordynamically stable rotor-GFB system. Finite element analysis of the rotor determines the rotor free-free (bending) natural modes and frequencies well beyond the maximum rotating frequency. The predicted damped natural frequencies and damping ratios of the rotor-GFB system reveal rotordynamic stability over the speeds of interest. The imbalance response predictions show that the predicted critical speeds and rotor amplitudes strongly agree with the test measurements, thus validating the developed rotordynamic model.

• Tribology and Lubricants
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• v.36 no.3
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1143-1145
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• 2002

IPMSM (Interior Permanent Magnet Synchronous Motor) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM. The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.44-49
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• 2003

Permanent magnet synchronous motor(PMSM) is widely used in many applications such as an electric vehicle. compressor drives of air conditioner and machine tool spindle drives. PMSM drive system have become a popular choice in various application, due to their excellent power to weight ratio. This paper is proposed maximum torque control for field weakening operation of PMSM drive. At low speeds, the reluctance torque is used to maximize the output for a given current level. This is achieved maximum torque per ampere(MTPA) by selecting an optimal value of the direct stator current component. At high speeds, the system reaches a point at which the inverter will not be able to supply the desired voltage. In this case it is necessary to make use of an increased value the direct current component. The proposed control algorithm is applied to PMSM drive system, the operating characteristics controlled by maximum torque control are examined in detail by simulation.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.9-16
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• 1983

흔히 자동차용 belt를 단순한 소모품으로 생각하여 대수롭지 않게 여기는 경향이 있으나 belt slip에 의한 동력의 손실은 매우 큰 것이며 특히 자동차용 belt에 있어서 그 중요성은 상당한 것이다. 왜냐하면 crankshaft에서의 중력이 belt를 통해서 water pump나 air compressor등에 전달되며 이때 동력전달이 제대로 안되는 경우에는 engine은 냉각수와 냉각팬에 의해 냉각이 되지 않아서 금방 고은소착 되기 때문이며, 또한 belt를 너무 조이는 경우에는 water pump bearing의 파손 등을 초래하기 때문에 belt의 정확한 길이 계산이 매우 중요하다. 그러나 이러한 중요성에도 불구하고 belt의 설계계산을 행하는 데는 많은 시간이 걸리며, 간혹 잘못 계산을 하는 경우에는 큰 문제가 발생할 수도 있기 때문에 belt계산의 기본이론식들을 전부 computer program 화하여 시간의 절약과 계산의 오류를 피하고자 한다. Program을 만들기 위해서 사용한 computer는 micro-computer로서 PET (Personal Electric Transactor)2001이며 사용한 언어는 BASIC이다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1169-1171
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• 2001

Synchronous reluctance motors(SynRM) for the application such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives require a wide field-weakening speed range. In order to improve the efficiency performance in such applications, this paper has examined the loss and the efficiency characteristics of SynRM mainly in the field-weakening speed region over the base speed. The control strategy in order to offer a efficiency optimization operation is shown and the copper and iron losses driven the equivalent circuit model of the machine is minimized. The usefulness of the proposed efficiency optimization control is verified through the SynRM durve system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.55-58
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• 2003

IPMSM (Interior Permanent Magnet Synchronous Motor) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.697-703
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• 2002

Interior permanent magnet synchronous motor(IPMSM) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM The optimal current can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1262-1272
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• 1997

An experimental study on the frequency control of an inverter heat pump to get the desired indoor room temperature has been conducted for the performance characteristics during the steady, 4, 8, and 16 step frequency operations. The heat pump model used in this study was operated to meet the experimental conditions of ASHRAE standard. The performance of the system was tested by measuring the temperature and pressure of the refrigerant, and cooling capacity, power consumption, etc. of the system. As the controlling frequency steps increased, the running time of the compressor increased as well as the electric consumption of the system and the cooling energy due to the wall heating load. However, the average cooling COP was improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5430-5437
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• 2011

The objective of this study is to investigate the cooling performances of the electrical air-conditioning system using electric driven scroll compressor for zero emission passenger vehicles. This air conditioner with air source was used R-134a as a refrigerant and installed in a real zero emission passenger vehicle for tests under various driving conditions. The cooling performance of the electrical air conditioner was affected by driving velocities and conditions of the tested vehicle. The condensing rate of the condenser during driving is better than that of the idle condition. The average cool down temperature in the cabin room decreased on average $5.2^{\circ}C$ with the increase of the outdoor temperature from $20.0^{\circ}C$ to $30.0^{\circ}C$. In addition, the cooling performances were sufficient for cooling loads of the tested passenger car under tested conditions.