• 전력전자학회논문지
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• 제2권2호
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• pp.49-56
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• 1997

스위치드 리럭턴스 전동기(switched reluctance motor : 이하 SRM 이라 칭함)는 가변 인덕턴스 프로파일의 비선형성과 리플성분이 포함된 펄스전류에 구동되는 본질적인 특성 때문에 토오크는 맥동성분을 포함한다. 본 논문에서는 토오크의 맥동에 영향을 미치는 전류파형 형태를 고찰하고, 속도나 부하에 관계없이 어드밴스 각(advance angle)와 여자전압을 제어함으로써 토오크 맥동을 저감할 수 있는 단일 펄스모드 스위칭 제어방법을 제안하였다. 그리고 설계 제작된 6/4 SRM을 이용하여 제안한 스위칭 제어방법의 타당성을 실험적으로 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.208-209
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• 2006

Voltage Transformer is used to transform high voltage into low voltage to input signal of protection relay. Most of the Voltage Transformers use the iron core which maximizes the flux linkage. The ratio of the Voltage Transformer depends on the transformer turns ratio. The current which flows in the Voltage Transformer has non-linear characteristic caused by hysteresis of the iron core, it causes a voltage loss in the winding impedances which makes measurement errors. This paper describes an error compensation method considering hysteresis characteristic. The proposed compensation method improves error by calculating the primary current from the exciting current of the hysteresis loop in the Voltage Transformer, compensating the voltage loss.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권1호
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• pp.1-7
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• 2004

This paper presents a sensorless control strategy of a PMSM(Permanent Magnet Sycchoronous Motor). This method is very simple to compute the position angle of a rotor. A principle and a practical solution are described. A sensorless control algorithm is proposed to remove a mechanical position sensor. The theory is based on the superposition principle. The state equation of a motor is divided into two conditions: one is the state equation of exciting voltage and phase current in a constraint, the other is the state equation of back EMF(Electromotive Force) and phase current in a short circuit. Based on the analysis, short circuit current by back EMF is computed and then the information of position angle is calculated. The proposed method is verified by experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.791-792
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• 2006

In motor design, an important factor is the content of silicon in coss material, which can effect the saturation of magnetic circuit and coss loss. While the content of silicon is high, the core loss will be reduced. At the same time, in order to assure the effective flux, the magnetizing current must be increased and then the copper loss becomes higher. Therefore the material with high content of silicon, which is used in the motor, can not always give the high efficiency. In this paper flux linkage of two different material s10 and s60 is compared according to the operating region and then exciting current to obtain same flux is estimated. By comparing core loss and copper loss between two material with the estimated current and flux linkage, this paper presents a criterion in determining the material for higher efficiency

• 한국정보통신학회논문지
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• 제14권12호
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• pp.2827-2835
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• 2010

임계치 이하의 자극이 주어지면 흥분막은 어떤 특이한 반응을 나타내지 않으나 어느 정도 이상이 되면 아주 다른 양상을 띄게 된다. 흥분막에는 이러한 특성이 있다는 것이 진작부터 알려져 있었고, 일부 연구자들이 이러한 현상을 전기적인 회로를 이용하여 정량적으로 해석하려 노력하였으나 그것은 임계치 이하의 경우에 대한 것에 불과하다. 특히 임계치 이상의 자극에 대한 반응을 정량적으로 연구한 경우는 극히 드물다. 그런데 전기회로와 생체는 비슷한 점도 있지만 다른 면도 많아서 그대로 이를 적용하기에는 무리가 있다. 이러한 이유로 인하여 본 논문에서는 생체막이 임계치 이상의 자극을 받았을 때에 어떠한 현상을 나타내는가를 전기적인 관점에서 정량적으로 연구하였다

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.77-80
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• 2003

An innovative ozonizer has been developed using a high frequency, surface discharge and a high purity Ti-Si-AI ceramic catalyst as a dielectric component. Using a type of thin film, a thin cylindrical compound ceramic catalyst layer was adhered to the outside surface of its inner electrode. An alternating current (AC) exciting voltage with frequencies from 0.6 KHz to 1.0 KHz and peak-to-peak voltages of 4-6 ㎸ was applied between the electrodes to produce a stable high-frequency silent discharge. A substantial reduction of the exciting voltage was also enabled by means of a thin Ti-Si-Al ceramic catalyst tube. As a result, the ozonizer can effortlessly obtain the required ozone concentration (50-60 g/$m^2$ for oxygen) and high ozone efficiency consumption power (180 g/kWh for oxygen) with-out the assistance of any particular methods. For purposes of this experiment, oxygen gas temperature was set at 2$0^{\circ}C$, with an inner reactor pressure of 1.6 atm at 600 Hz and a flow rate of 2 l/min.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 춘계학술대회 논문집
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• pp.97-100
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• 1992

The Degradation mechanism of the ZnO-varistor fabricated with the content of a 3-Composition seed grain is discussed using the method of Thermally Stimulated Current (TSC). The spectra of TSC is measured in the temperature range of -130～270$^{\circ}C$ with a various forming electric fields E$\sub$f/, temperature T$\sub$f/ time tf, and a various rising rate of temperature. It is observed that there are appeared the peaks of ${\alpha}$, ${\alpha}$$_2$, ${\beta}$ and ${\gamma}$from high temperature in a TSC spectrum. It seems that ${\alpha}$$_1$ peak is due to thermal depolarization of donor ions forming the space charge in the depletion layer, and ${\alpha}$$_2$peak is due to the detrapping of trapped electrons in deep trap level of intergranular layer, and ${\beta}$ peak is due to the thermal exciting of carrier existing in the donor level of grain itself, and ${\gamma}$ peak is due to the thermal exciting of trapped carrier in all shallow trap site randomly distributed in the inner of sample and/or a intrinsic impurity existing in it.

• 한국소음진동공학회논문집
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• 제18권11호
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• pp.1192-1198
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• 2008

In this paper, the vibration and shock of an HDD car-holder are reduced through vibration analysis and a structural modification. In order to identify the exciting frequency components of vibration and shock, vibration signals are measured and analyzed from the wind shield or dashboard. In addition, the modal test for the current HDD car-holder is performed to investigate the dynamic characteristics of the car-holder. From these experiments, it is found that the exciting frequencies coincide to the natural frequencies of the car-holder. For the purpose of avoiding resonance, some FEM simulations are carried out and then structural modifications are made for the car-holder. Based on the results of simulations, a prototype of new car-holder are manufactured and tested to demonstrate the reduction of vibration and shock. It is verified by the test that a considerable amount of vibration and shock are reduced.

• 대한약침학회지
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• 제19권1호
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• pp.7-15
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• 2016

Objectives: Malaria has been a major global health problem in recent times with increasing mortality. Current treatment methods include parasiticidal drugs and vaccinations. However, resistance among malarial parasites to the existing drugs has emerged as a significant area of concern in anti-malarial drug design. Researchers are now desperately looking for new targets to develop anti-malarials drug which is more target specific. Malarial parasites harbor a plastid-like organelle known as the 'apicoplast', which is thought to provide an exciting new outlook for the development of drugs to be used against the parasite. This review elaborates on the current state of development of novel compounds targeted againstemerging malaria parasites. Methods: The apicoplast, originates by an endosymbiotic process, contains a range of metabolic pathways and housekeeping processes that differ from the host body and thereby presents ideal strategies for anti-malarial drug therapy. Drugs are designed by targeting the unique mechanism of the apicoplasts genetic machinery. Several anabolic and catabolic processes, like fatty acid, isopenetyl diphosphate and heme synthess in this organelle, have also been targeted by drugs. Results: Apicoplasts offer exciting opportunities for the development of malarial treatment specific drugs have been found to act by disrupting this organelle's function, which wouldimpede the survival of the parasite. Conclusion: Recent advanced drugs, their modes of action, and their advantages in the treatment of malaria by using apicoplasts as a target are discussed in this review which thought to be very useful in desigining anti-malarial drugs. Targetting the genetic machinery of apicoplast shows a great advantange regarding anti-malarial drug design. Critical knowledge of these new drugs would give a healthier understanding for deciphering the mechanism of action of anti-malarial drugs when targeting apicoplasts to overcome drug resistance.

• 조명전기설비학회논문지
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• 제14권4호
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• pp.31-38
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• 2000

본 논문에서는 동기속도 이상의 풍속 영역에서 계풍연계된 DFTG(Doubly-Fed Induction Generaior) 시스템올 이용하여 발전기의 속도, 출력, 역률 제어에 대한 연구를 하였다. 이를 위하여 회전자 권선을 통하여 회전자 여자 주파수와 전압을 인가하였고,DBG의 전력소류와 등가회로의 정상상태 식을 해석하였다. 발전기의 속도와 고점차 일정출력제어는 회전자 여자주파수에 의해 이루어지고, 발전기의 정상적인 동작은 회전자 여자전류가 정격값올 넘어서는 안된다. 따라서 회전자 여자주파수에 의한 일정 출력운전상태에서 회전자 여자전류를 정격값이 되도록 회집자 여자전압을 제어여, 고정자 역률이 최적이 되도 DFIG를 운전하였다.