• 생태와환경
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• 제39권4호통권118호
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• pp.424-434
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• 2006

박테리아-동물플랑크톤의 영양적 관계와 이에 미치는 요인들을 파악하기 위하여 2005년 4월부터 12월까지 팔당호 생태계의 영양상태가 다른 팔당댐앞과 경안천 두 지점을 선정하여 동물플랑크톤의 여과율과 박테리아의 C-flux를 분석하였다. 동물플랑크톤은 소형 (Microzooplankton, MICZ: 60-200 ${\mu}m$)과 대형동물플랑크톤(Macrozooplankton, MACZ: >200 ${\mu}m$)으로 구분하여 각 그룹에 대하여 별도로 섭식률을 조사하였다. 두 지점에서 박테리아 밀도와 계절적 변화양상은 유사하게 나타났다. 동물플랑크톤은 두 지점 모두 윤충류(Brachionus, Keratella, Polyathra)가 수적으로 크게 우점하였으나, 탄소생물량은 지각류(Daphnia)가 가장 높았다. 동물플랑크톤은 봄에 높은 밀도와 탄소생물량을 보였고 여름철 집중강우 시기를 기점으로 크게 감소하였다. 지점별로는 경안천에서 상대적으로 높은 탄소생물량이 나타났다. 박테리아에 대한 동물플랑크톤 여과율은 팔당댐앞에서 봄, 가을철에 높고 여름철에 낮게 나타나는 계절에 따른 변화가 명확하게 나타난 반면, 경안천에서는 팔당댐앞과는 달리 여름철에 높게 나타났다. C-flux는 두 지점 모두 봄철과 가을철에 높게 나타났다. 군집여과율과 박테리아 C-flux는 MACZ가 MICZ보다 높았고, 그 정도는 경안천에서 더 높게 나타났다. 여름철의 집중강우로 인한 짧은 체류시간과 수체의 교란이 동물플랑크톤의 섭식에 영향을 미치는 것으로 파악되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.48-53
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• 1989

We attempt to achieve both high dynamic performance and maximal power efficiency by means of linear decoupling of rotor speed (or motor torque) and rotor flux. The induction motor with our controller possesses the input-output dynamic characteristics of a linear system such that the rotor speed (or motor torque) and the rotor flux are decoupled. The rotor speed (or motor torque) responses are not affected by abrupt changes in the rotor flux and vice versa. The rotor flux need not be measured but is estimated by the well-known flux simulator. The effect of large variation in the rotor resistance on the control performances is minimized by employing a parameter adaptation method. To illuminate the significance of our work. we present simulation and experimental results as well as mathematical performance analyses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.633-635
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• 2004

The current limiting characteristics of the flux-lock type superconducting fault current limiters(SFCLs) were investigated. The flux-lock type SFCL consists of a flux-lock reactor and high-T_c superconducting (HTSC) element. In this SFCL the initial limiting current level can be controlled by adjusting the inductances of two coils. In this paper, the operational characteristics of the flux-lock type SPCL were analyzed and the current Limiting characteristics of it were investigated through the experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1036-1038
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• 2000

This paper presents an implementation of digital motion control system of induction motor vector drives with a direct torque control(DTC) using the 16bit DSP TMS 320F240. The DSP controller enable enhanced real time algorithm and cost-effective design of intelligent controllers for induction motors which can be yield enhanced operation, fewer system components, lower system cost, increased efficiency and high performance. The system presented are stator flux observer of current model that inputs are current sensing of motor terminal and rotor angle, and optimal switching look-up table by using fully integrated control software. The developed system are shown a good motion control response characteristic results and high performance features using 2.2Kw general purposed induction motor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.418-422
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• 2001

To achieve a high performance in direct vector control of induction motor, it is essential to correct estimation of rotor flux. The accuracy of flux observers for induction machines inherently depends on parameter sensitivity. This paper presents an analysis method for conventional flux observers using Parameter Sensitivity. The Parameter sensitivity is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation. We define the ratio between real flux and estimated flux as the transfer function, and analyzed a parameter sensitivity of this transfer function by simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.7-10
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• 2001

To obtain a high performance in a direct vector controlled induction machine, it is essential to correct estimation of rotor flux. The accuracy of flux observers for induction machines inherently depends on parameter sensitivity. This paper presents an analysis method for conventional flux observers using Parameter Sensitivity. The Parameter sensitivity is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation. We define the ratio between real flux and estimated flux as the transfer function, and analyzed a parameter sensitivity of this transfer function.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1176-1178
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• 2001

To obtain a high performance in a direct vector controlled induction machine, it is essential to correct estimation of rotor flux. The accuracy of flux observers for induction machines inherently depends on parameter sensitivity. This paper presents an analysis method for conventional flux observers using parameter Sensitivity. The Parameter sensitivity is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation. We define the ratio between real flux and estimated flux as the transfer function, and analyzed a parameter sensitivity of this transfer function.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.137-141
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• 2005

A transverse flux, PM-exited linear motor (TFM-LM) with inner mover was designed and built. Its output power density is higher and its weight is lower than those of the conventional PM exited linear synchronous motors (PM LSM). To obtain the maximum thrust force under the given volume, the thrust force density with respect to the ratio of the slot width and the length of pole pitch is analyzed by the 3-dimension finite element method (FEM). Finally, calculated static thrust forces was compared with the experimental values. The calculated and measured performance of the transverse flux, PM-exited linear motor with inner mover revealed great potential for system improvements by reducing the mass of the linear motor. For examples, when this motor was applied to a ropeless elevator, it was possible to increase the power density by more than 400% over the conventional PM-LSM. The results of this study recommend this type of motor for the ropeless elevator or gearless direct linear driving system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권3호
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• pp.120-126
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• 2005

This paper deals with a Double-type Transverse Flux Linear Motor which can be applied to high power system. This type can reduce overall system volume because it has a double flux path, and less number of phases and turns comparing with prototype for one phase. This machine is based on permanent magnet excitation, and the pole shape is designed to reduce attraction force between stator and mover poles. In the paper, the basic configuration of double type is introduced first, and the principle of movement is explained. After performing the characteristic analysis by 3-dimensional equivalent magnetic circuit network, the results are discussed.

• 한국안전학회지
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• 제16권4호
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• pp.88-95
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• 2001

Stator core loss has significant adverse effects when an induction motor is controlled by the conventional vector control method. Therefore, taking core toss into account should make it possible to control the torque very precisely. This paper proposes a speed sensorless vector control method for an induction motor at optimum efficiency and high response taking core loss account. The proposed vector control system consists of a speed adaptive rotor flux observer which takes core loss into account and employs a direct vector control which compensates for the influence of core loss. Also, in this paper, a vector controlled induction motor with a deadbeat rotor flux controller is developed. The method ensures optimum efficiency in the steady state without degradation of the dynamic response. The validity of the proposed technique is confirmed by simulation results for induction motor drive system.