• 한국전자통신학회논문지
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• 제9권7호
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• pp.761-766
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• 2014

본 연구는 1 V 미만 전원 전압에서 동작 가능한 직렬공진 바렉터 통합형 평형 공통 게이트 콜피츠 전압제어 발진기와 직렬공진 바렉터 통합형 평형 공통 드레인 콜피츠 전압제어 발진기의 탱크회로에서 나타나는 발진전압에 대한 해석적 연구를 수행하고 이를 시뮬레이션에 의해 확인한다. 해석적 연구의 결과는 직렬공진 바렉터 통합형 평형 공통 게이트 콜피츠 전압제어 발진기가 직렬공진 바렉터 통합형 평형 공통 드레인 콜피츠 전압제어 발진기보다 더 큰 발진전압을 탱크회로에 유도할 수 있으며 따라서 저 위상 잡음 발진에 보다 더 적합한 발진기임을 밝혀준다.

• 대한전기학회논문지:전력기술부문A
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• 제49권5호
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• pp.226-232
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• 2000

This paper presents application results of the augmented matrix eigen-sensitivity theories to TCSC siting problem for damping the inter-area low frequency oscillation in the large KEPCO system. First and second-order eigen-sensitivities of the inter-area low frequency oscillation in the large KEPCO system. First and second-order eigen-sensitivities of the inter-area mode are computed fro changes in susceptance of the transmission lines. The lines having high sensitivity are chosen as the initial candidates for installing TCSC. Then for each of the chosen candidates, Bodeplot of the transfer function with line susceptance as the input and the bus voltage at one side of the line as the output is computed. Using the Bode plots, the lines having any zeros near the inter-area mode are screened out since design of TCSC controller is very difficult in such a case. The $H_{\infty}$ TCSC controller installed at any finally chosen candidate is found to be effective in damping the inter-area oscillation, and the proposed TCSC siting algorithm is proved to be valid. Design of $H_{\infty}$ controller is described in Part IIof this paper.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.374-378
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• 2014

PID control method usually has problems of overshoot and oscillation in high order control system, therefore, it is important to improve the control method so as to reduce the overshoot and oscillation. Based on MATLAB simulation, a permanent magnet (PM) DC servomotor control system is studied in this paper. The motor is modeled according to the universal motor theory, and with the help of the fourth order Ronge-Kutta method, its speed control is simulated and compared between two different dual closed-loops PWM control methods. This case study helps undergraduate students to better understand theories related to electrical engineering, such as electrical machinery, power electronics and control theory, as well as digital solution of state equations.

• 전기학회논문지
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• 제63권7호
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• pp.875-882
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• 2014

In this paper, we propose a new parameter estimation method that can deal with the data of multiple time intervals simultaneously. If there are common modes in the multiple time intervals, it is possible to create a new polynomial by summing the coefficients of the prediction error polynomials of each time interval. By calculating the roots of the new polynomial, it is possible to estimate the common modes that exist in each time interval. The accuracy of the proposed parameter estimation method has been proven by using appropriate test signals.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1136-1141
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• 1992

This paper proposes a control technique to obtain high frequency quasi sinusoidal DC-Link waveform permitting zero-voltage-switching(ZVS). This operation results in reduction of commutation stress and switching losses in the power devices because they cause no switching loss in principle. But in existing control methods, the resonant capacitor voltage is not frequently made of zero-cross oscillation. We propose an optimum control stratege which can sustain oscillation and keep the capacitor voltage at an allowable level. Some experimental results are included to confirm the validity of the analytical results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.312-315
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• 2004

This paper presents a tuning-free conditional integration anti-windup strategy for induction machine with Proportional-Integral (PI) type speed controller. The on/off condition of integral action is determined by the frequency domain analysis of machine torque command without a prior knowledge of set-point changes. There are no tuning parameters to be selected by users for anti-windup scheme. In addition, the dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time even in the change of operating conditions. This algorithm is useful in many high performance induction machine applications not to allow the oscillation and overshoot of speed/torque responses. The main idea can be extended to general applications such as chemical processes and industrial robots.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.16-17
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• 2006

In this paper, RCF analysis method which is very powerful to analyze non-continuous systems with switching elements is applied to small signal stability problems. As an effect of switching operations, the eigenvalues of system can be changed and newly unstable oscillation modes may be occurred. Also, changing firing angles of switching equipments may make the system stable or unstable. As an illustrating example, the oscillation modes of the system with different firing angles are computed by the RCF analysis method.

• International Journal of Fluid Machinery and Systems
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• 제2권3호
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• pp.260-268
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• 2009

The effects of acoustic modes in the penstock on the self-excited oscillation in hydraulic power system were studied by assuming a finite sound velocity in the penstock. The flow in the draft tube is considered to be incompressible assuming that the length of the draft tube is smaller than the wavelength of the oscillation. It was found that various acoustic modes in the penstock can become unstable (amplified) by the diffuser effect of the draft tube or the effect of swirl flow from the runner. Their effects on each mode are discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.270-273
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• 2003

The design, fabrication, and measured result of a 4.7 GHz differential VCO (Voltage Controlled Oscillator) for a 5.2 GHz WLAN (Wireless Local Area Network) applications is presented. The circuit is designed in a 0.35 mm technology employing three metal layers. The design is based on a fully integrated LC tank using spiral inductors. Measured tuning range is 10% of oscillation frequency with a control voltage from 0 to 3.0 V. Oscillation power of $\square$ 2.3 dBm at 4.63 GHz is measured with 21 mA DC current at 3V supply. The phase noise is $\square$ 104.17 dBc/Hz at 1 MHz offset.

• 선박안전
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• 통권37호
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• pp.35-44
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• 2014

해상 및 육상용 살균방식으로 UV를 사용하는 시스템이 주종을 이루고 있으며, 의료, 생활, 산업용 시스템에 널리 적용되고 있으며, 근래에는 평형수 처리 방식으로 UV를 적용하는 사례가 등장하고 있다. UV 광원으로는 다양한 램프가 있으며 그 중 제논플레시 램프는 강한 섬광형 방전과 함께 다량의 UV를 방출하는 특성이 있어 매우 효과적이다. 다만, 타 광원에 비하여 높은 방전전압으로 인하여 기존의 전원장치 설계 방식으로는 장치의 크기가 크고 복잡한 문제가 있었으며, 이를 개량하기 위한 본 연구에서는 트랜스포머의 자가 공진(self-resonance)을 이용한 설계 기법을 제안하며, 트랜스포머의 특정주파수에서 고유임피던스 성분을 이용하여 출력전압을 필터링하면 제논방전관이 자가 발진방식으로 동작하므로 종래의 회로구성보다 간단하고 경제적인 아크방전 파워 스테이지의 구성이 가능하다.