• 전기학회논문지
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• 제59권7호
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• pp.1332-1339
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• 2010

This paper presents a large signal analysis of ring-type oscillators with feed forward and negative skewed delay scheme. The analysis yields the frequency increase factor due to two schemes. The large signal analysis is needed, because small signal model is limited to the initial stage of oscillation[1]. For verification of the frequency increase factor, simulation were done under the same conditions for the two different types of ring oscillators, i.e., with and without feed forward and negative skewed delay scheme. Simulation results are in good agreement with predictions based on analysis.

• 조명전기설비학회논문지
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• 제14권5호
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• pp.12-18
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• 2000

본 연구에서는 Gl5내 파티클의 각종 위치에서 발생하는 초음파 신호와 부분방전 신호의 페턴을 비교 분석하였다. 파티클 위치에 따른 초음파 신호와 부분방전 신호 패턴의 특칭은 전극 부착시 양의 반주기에서 큰 초음파 신호와 큰 부분방전 신호가 주기적으로 나타났으며, 외함 부착시에는 음의 반주기에서 큰 초음파 신호와 큰 부분 방전 신호기 주기적으로 나타났다. 그리고 스페이서 부착시에는 양, 음의 반주기에서 초음파 신호와 큰 부분방전 신호가 주기적으로 나타나고 있다. 또한 자유운동시에는 충돌에 의한 초음파 신호와 큰 부분방전 신호가 비주기적으로 나타났다. 이상의 결과로부터 초음파 신호와 부분방전 신호 패턴을 비교, 분석히변 GIS 내부에 존재하는 파티를의 위치 추정이 가능함을 알 수 있었다.

• 전력전자학회논문지
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• 제11권6호
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• pp.535-542
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• 2006

저궤도 인공위성 전력계 시스템의 설계 및 해석을 위한 태양전지 전력조절기의 대신호 안정도해석을 수행한다. 태양전지 전력조절기에서 제어가능한 모든 방법에 따른 태양전지에서 바라본 태양전지 전력조절기의 부하특성을 분류하고, 상태공간해석을 이용하여 태양전지 시스템의 대신호적 안정도를 해석한다. 또한, 본 논문에서는 태양전지 전력조절기의 부하특성을 정전력부하에서 정저항부하로 변환하여 대신호적인 안정도를 확보하는 비선형변환을 제안한다. 제안된 변환기법을 통해 최대전력점 추적제어나 배터리 충전제어 및 전류분배제어가 가능한 병렬 모듈 태양전지 레귤레이터에 적합한 단일 전류 제어기를 구성한다. 제안된 대신호 해석과 저항제어를 검증하기위해, 200W급 태양전지와 100W급 태양전지 전력조절기 두 모듈을 병렬로 구성하여 실험하였다.

• 전기학회논문지P
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• 제51권1호
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• pp.52-54
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• 2002

This research presented in this paper focuses on a system development for checking stator's wedge of large generator in heavy industry. The system is composed of impactor, A/D converter and digital signal processing board. Also this paper proposes a method for detection of stator's insulating state using analysis algorithm. As developed impact system is acting, impact wave is generated real time and transferred data to microprocessor. Using communication program this signal move microprocessor to hard directory of note book with 1000 data/sec. The developed system and analysis program performed very well by real stator's wedge in large generator.

• 전기의세계
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• 제28권8호
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• pp.51-56
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• 1979

MOSFET의 모델을 설정하여 여러 bias 조건하에서 연결방정식과 Poisson 방정식을 numerical method로 풀어 그 해로서 전자와 정공의 분포와 전위분포를 구하였으며 또한 그 결과를 종래의 analytic한 이론들과 비교하여 보다 정확하고 CAD(Computer Aided Design)에 적합한 모델을 제안하였다.

• Journal of Power Electronics
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• 제18권6호
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• pp.1912-1919
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• 2018

The output capacitance of power semiconductor devices is important in determining the switching losses and in the operation of some resonant converter topologies. Thus, it is important to be able to accurately determine the output capacitance of a particular device operating at elevated power levels so that the contribution of the output capacitance discharge to switch-on losses can be determined under these conditions. Power semiconductor switch manufacturers usually measure device output capacitance using small-signal methods that may be insufficient for power switching applications. This paper shows how first principle methods are applied in a novel way to obtain more relevant large signal output capacitances of Gallium-Nitride (GaN) FETs using the drain-source voltage transient during device switch-off numerically. A non-linear capacitance for an increase in voltage is determined with good correlation. Simulations are verified using experimental results from two different devices. It is shown that the large signal output capacitance as a function of the drain-source voltage is higher than the small signal values published in the data sheets for each of the devices. It can also be seen that the loss contribution of the output capacitance discharging in the channel during switch-on correlates well with other methods proposed in the literature, which confirms that the proposed method has merit.

• 대한산업공학회지
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• 제32권2호
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• pp.133-140
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• 2006

Large signal type data sets are difficult to classify, especially if the data sets are non-stationary. In this paper, large signal type and non-stationary data sets are wavelet transformed so that distinct features of the data are extracted in wavelet domain rather than time domain. For the classification of the data, a few wavelet coefficients representing class properties are employed for statistical classification methods : Linear Discriminant Analysis, Quadratic Discriminant Analysis, Neural Network etc. The application of our wavelet-based feature selection method to a mass spectrometry data set for ovarian cancer diagnosis resulted in 100% classification accuracy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1235-1238
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• 2004

This paper presents the large-signal transient analysis of a self-driven active-clamp forward converter, eliminating the extra drive circuit for the active clamp switch. The operation principle of the converter was presented and experiential results were used to verify the analyzed results. A 50-W prototype converter built and tested it. From the tested results, input transient response and load transient response of the converter were established.

• 한국멀티미디어학회논문지
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• 제19권8호
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• pp.1297-1309
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• 2016

In this paper, an efficient connected component labeling (CCL) method was proposed. The proposed method is based on GPU parallelism. The CCL is very important in various applications where images are analysed. However, the label of each pixel is dependent on the connectivity of adjacent pixels so that it is not very easy to be parallelized. In this paper, a GPU-based parallel CCL techniques were proposed and applied to the analysis of radar signal. Since the radar signals contains complex and large data, the efficiency of the algorithm is crucial when realtime analysis is required. The experimental results show the proposed method is efficient enough to be successfully applied to this application.

• 대한전기학회논문지:전력기술부문A
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• 제49권4호
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• pp.168-176
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• 2000

This paper presents the Hessenberg method, a new sparsity-based small signal stability analysis program for large interconnected power systems. The Hessenberg method as well as the Arnoldi method computes the partial eigen-solution of large systems. However, the Hessenberg method with pivoting is numerically very stable comparable to the Householder method and thus re-orthogonalization of the krylov vectors is not required. The fractional transformation with a complex shift is used to compute the modes around the shift point. If only the dominant electromechanical oscillation modes are of concern, the modes can be computed fast with the shift point determined by Fourier transforming the time simulation results for transient stability analysis, if available. The program has been successfully tested on the New England 10-machine 39-bus system and Korea Electric Power Co. (KEPCO) system in the year of 2000, which is comprised of 791-bus, 1575-branch, and 215-machines. The method is so efficient that CPU time for computing five eigenvalues of the KEPCO system is 3.4 sec by a PC with 400 MHz Pentium IIprocessor.