• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.49-55
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• 2006

Applied by periodic Stimulating Currents in Bonhoeffer -Van der Pol(BVP) model, chaotic and periodic phenomena occured at specific conditions. The conditions of the chaotic motion in BVP comprised 0.7182< $A_1$ <0.792 and 1.09< $A_1$ <1.302 proved by the analysis of phase plane, bifurcation diagram, and lyapunov exponent. To control the chaotic motion, two methods were suggested by the first used the amplitude parameter A1, $A1={\varepsilon}((x-x_s)-(y-y_s))$ and the second used the temperature parameterc, $c=c(1+{\eta}cos{\Omega}t)$ which the values of ${\eta},{\Omega}$ varied respectlvly, and $x_s$, $y_s$ are the periodic signal. As a result of simulating these methods, the chaotic phenomena was controlled with the periodic motion of periodisity. The feasibilities of the chaotic and the periodic phenomena were analysed by phase plane Poincare map and lyapunov exponent.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.286-293
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• 2002

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these Points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in real system for maximum photovoltaic power tracking control.

• Development and Reproduction
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• v.23 no.4
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• pp.305-311
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• 2019

Small intestine has a structure called villi that increases the mucosal surface area for nutrient absorption. Intricate and tight epithelial-mesenchymal interactions are required for villi development. These interactions are regulated by signaling molecules, physical forces, and epithelial deformation. Signaling molecules include hedgehog (Hh), bone morphogenetic protein (BMP) and Wnt ligands. The Hh ligand is expressed from the epithelium and binds to the underlying mesenchymal cells, resulting in aggregation into mesenchymal clusters. The clusters express BMP and Wnt ligands to control its size and spacing between clusters. The clusters then form villi. Despite the fact that the villi formation is studied extensively, we do not have a complete understanding. In addition, the recent study shows there is a great relationship between the overexpression of the Hh signal and development of cancer in the gastrointestinal tract. Therefore, signaling between epithelial and mesenchymal cells and their physical interactions will be discussed on this review.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.170-174
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• 2005

The purpose of this study is to design the digital surge counter for lightning arresters. The used detecting method for surges is using the signal of both ends of ZnO varistor. The electronic detecting parts of the digital counter are arranged in outside of main processer for protecting it from noise. The detecting parts change detected signals into small signals. The countermeasures for noises are (1) Shielding (2) Reinforcement of power circuits (3) Cables & Circ1e core (4) Watch-doc & control of input signals.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.310-312
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• 1994

A partial shunt regulator (PSR) which is the power regulator of KOREASAT is modeled. The modeling of the PSR consist of solar array, power circuit, controller. and load models. To realize simple structure. a voltage source of the PSR controller is used the output voltage of the PSR. The model of the PSR has very complex structure with two additional coupled feedback loops. The complex model is simplified to a simple meaningful model with only main feedback control loop. The proposed model is compared to a PSR model with DC voltage source at the PSR controller. The proposed PSR model is verified by comparing the model with SPICE simulation for small signal analysis.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.6-8
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• 1994

Switched reluctance motor drive system is well known as a variable speed drive system because it has a simple motor structure and a simple driving circuit. Widely slotted photo interrupter has been investigated as a position sensor for SRM speed control because it has advantages of low cost and simple structure. However it has low resolution and it produces dead-time signal. This paper studies variable speed SRM drive system with slotted photo-interrupter. Controller in this study is constructed by using fuzzy controller that covers system nonlinearities and small perturbations in sufficiency. The performance of this system is evaluated through computer simulation and experiment results.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1143-1146
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• 1998

Static excitation systems with high gain and fast response times greatly aid transient stability. but at the same time tend to reduce small signal stability. The objective of the power system stabilizer(PSS) control is to provide a positive contribution to damping of the generator rotor angle swings, which are in a broad range of frequencies in the power system. Therefore, this paper shows the field test results for the GE's EX2000 PSS tuning on units at Seo-Incheon power plant. The test is to verify that the PSS response meets GE's design, criteria. The responses of generator terminal voltage, active power, field voltage and current were analyzed and PSS gain was tuned by 10 finally.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.275-279
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• 1998

In this paper, the authors propose a new method for improving identification method of linear system by us-ing M-transform. The authors has recently proposed a new mettled for linear system identification by use of M-transform. In this method, the input signal n(i) must have the same period N as that of the M-sequence. When N becomes large, it will take a long time to compute. To overcome this difficulty, we propose a new approach of system identification by using a small size matrix. The results of simulation show a good agreement with the theoretical considerations.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.202-215
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• 2013

This paper proposes a SEPIC-input, self-driven, active clamp ZVS converter, where an auxiliary winding and a RC delay circuit are employed to drive the active clamp switch and to achieve asymmetrical duty control without any other extra circuits. Based on the fixed dead time and the resonance between capacitors and inductors, both the main switch and the auxiliary switch can rule the ZVS operation. Detailed operation modes are presented to illustrate the self-driven and ZVS principles. Furthermore, an accurate state-space model and the transfer functions of the proposed converter have been presented and analyzed in order to optimize dynamic performance. The model provides efficient prediction of converter operations. Experimental results, based on a prototype with 80V input and 15V/20A output, are discussed to verify the transient and steady performance of the proposed converter.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.115-118
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• 2000

본 연구에서는 소형 DC 모터 완성품의 제품검사에서 객관성이 결여된 판정기준인 작업자의 청각에 의한 관능검사에 대신하여 자동 진단 시스템의 적용으로 고신뢰성을 확보하기 위하여 음향신호를 취득하여 분석하는 방법을 제안하였다. 소형 모터가 회전할 때 발생하는 음향신호를 마이크로폰으로 취득하여, 취득한 신호에 단구간 Hanning Window를 걸어 시간에 따라 이동하면서 신호의 주파수 성분을 시간에 따라 전개하는 STFT(Short-Time Fourier Transform) 기법으로 정상적인 모터와 이상인 모터에서 발생하는 음향신호를 분석하였다.