• 한국소음진동공학회논문집
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• 제25권11호
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• pp.771-778
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• 2015

In this work, vibration characteristics of high speed rotary bell cup for paint atomizer are numerically investigated. New type of bell cup model is proposed and additional corresponding models with design parameter variations for length and diameter are constructed. Dynamic characteristics, such as natural frequencies and corresponding mode shapes, are studied for each model as a first step. To investigate operation stability, critical speed of rotary bell cup is numerically analyzed based on Campbell diagram and separation margin between operating speed and critical speed is identified. Unbalance vibration responses are also investigated with respect to design parameter variation, operating speed and balancing quality grade of G. Then the proper design guideline for stable operation of high speed rotary bell cup for paint atomizer is suggested.

• 한국자동차공학회논문집
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• 제13권3호
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• pp.35-40
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• 2005

In the present study, the influence of operating conditions on fuel economy for hybrid electric vehicle was analyzed. In order to accomplish this, vehicle speed, engine speed, battery current and voltage, SOC (state of charge),motor speed and torque, generator speed and torque, engine coolant temperature etc. were measured in real time. The tests were carried out under different driving cycles which are urban and highway cycles, KOREA CITY cycle and on-road driving, and also under various operating conditions such as different initial SOC, with or without regenerative braking etc.. Generally, conventional gasoline engines show a poor fuel economy at stop and go driving, because braking energy is wasted and the engine is operated in low thermal efficiency regions. However, in case of hybrid vehicles, higher fuel economy can be obtained because of utilizing the maximum thermal efficiency regions of engine, idling stop of engine, and regenerative braking etc..

• 설비공학논문집
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• 제27권5호
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• pp.233-240
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• 2015

This paper discusses compressors operating number control strategy using cooperative logic to cope with variable partial load for high efficiency of a centrifugal water chiller. The cooperative logic is composed of a speed-up and speed-down controller, enabling smooth operation of compressors and equivalent distribution of thermal load in each compressor. This centrifugal water chiller design can be operated with high efficiency without incurring excessive energy waste and large transient phenomena at partial load states. Simulations in MATLAB and experiments in a real chiller system were conducted and verified the high efficiency control of a centrifugal water chiller achieved by the suggested strategy.

• 해양환경안전학회지
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• 제21권6호
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• pp.784-789
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• 2015

본 연구는 소형 고속정의 운항한계를 검토하기 위하여 수행되었다. 일반적으로 내항성능의 검토는 선형의 결정 단계 전에 이루어지지만 본 연구는 선박의 건조가 완료된 후에 이루어졌다. 검토 결과, 종동요, 수직 및 수평가속도, 슬래밍의 운동성능은 특정한 조우각을 제외하고는 만족하였으나 갑판침수의 경우에는 해석을 수행한 모든 조건에서 만족하지 않았다. 이것은 대상선박의 크기가 소형이기 때문에 선박의 속도나 파도와의 조우각보다는 해상상태가 설정한 내항성능 기준의 만족 여부에 더 큰 영향을 미쳤기 때문으로 보인다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3013-3018
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• 2008

Supercharging system was adopted to investigate the influence of boost pressure on operating range, brake specific fuel consumption (BSFC) and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range. The result showed that operating range with boost was expanded up to 41.9% compared to naturally aspirated LTC condition due to increased mixing intensity. The boosted LTC engine showed low BSFC value and dramatically reduced soot emission under all operating range compared with high speed direct injection (HSDI) mode. Finally, this paper presents the boosted LTC map of emission and the strategy of improved engine operating range.

• 대한전자공학회논문지SP
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• 제44권1호
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• pp.64-69
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• 2007

본 논문은 고속 UWB(Ultra Wide Band) 시스템을 위한 인터폴레이터를 구현한다. 구현된 고속 UWB 시스템용 인터폴레이터는 기존 가변 파라미터를 이용한 큐빅 인터폴레이터에 병렬 처리 기술과 파이프라인 기법을 동시에 적용한다. Stratix II EP2S60F1020C3를 타겟 디바이스로 실험한 결과, 최대지연경로 속도와 최대지연경로 주기가 각각 최대 102.42MHz와 9.764ns가 되었고, 동작속도는 최대 대략 190%이상 향상되었음을 알 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2098-2100
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• 1997

The present paper investigates the optimal operation of a switched reluctance motor such that overall drive efficiency is maximized under a variable supply voltage. The operation under a variable supply voltage exhibits the improved drive efficiency in the full range of operating torque and speed, and exhibits the expanded range of operating torque and speed. Furthermore a variable supply voltage may be utilized in reducing torque ripple.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.95-99
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• 2000

New locking algorithm of DLL is proposed to improve the locking speed and low power dissipation in this paper, In spite of using the architecture of delay controller, low power consumption is acquired by operating only one controller at once and fast locking speed is accomplished by initial setting from the coarse controller. The proposed DLL circuit is operated from 50MHz to 200MHz and locked within 6 cycle at all of operating frequency.

• 전기학회논문지P
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• 제56권2호
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• pp.74-82
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• 2007

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. This paper proposes efficiency optimization control of IPMSM drive using adaptive fuzzy learning control fuzzy neural network (AFLC-FNN) controller. In order to maximize the efficiency in such applications, this paper proposes 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. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using AFLC-FNN controller. Also, this paper proposes speed control of IPMSM using AFLC-FNN and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The proposed control algorithm is applied to IPMSM drive system controlled AFLC-FNN controller, the operating characteristics controlled by efficiency optimization control are examined in detail.

• 한국정밀공학회지
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• 제30권7호
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• pp.667-672
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• 2013

This paper presents the development of a condition monitoring system that monitors the operating conditions of a reduction unit, such as the bearing temperature, gearbox vibration, and gear oil deterioration, and notifies the operator of potential problems or abnormal conditions. A series of field tests on high-speed rail and conventional lines was performed to identify the characteristics of temperature rise and vibration levels on the reduction unit during operation. The monitoring system was designed based on the proper sensor selection, measurement method, and signal analysis to optimize the interface with the operating system of high-speed trains. Application of this monitoring system to high-speed trains will play an important role in their proper maintenance and safe operation.