• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.599-600
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• 2006

본 연구는 솔더의 리프로우 현상으로부터 제안되었다. 솔더는 원형 흡착 층 위에서 녹게 되면 단위 면적당 표면 에너지를 최소화 하려는 특성 때문에 구형이 되는데, 이는 자기정렬 기구의 핵심이기도 하다. 본 연구에서 제안되는 새로운 설계가 기존의 설계와 가장 큰 차이점은 그림 1에서 처럼 솔더의 리프로우에 의해 측면 접합을 한다는 것이다. 대부분의 기존 실장 기술은 접합 면과 피 접합 면이 서로 마주보고 있으며 서로 맞닿아야만 접합이 이루어 지는 "intimate contact" 원리인 반면, 본 연구에서 제안된 개념은 접합 면과 피 접합 면이 쏠더에 의해 끼워진 상태에서 측면 접합되는 원리이 기 때문에 접합 면끼리 서로 인접하지 않아도 접 합은 자연적으로 완성되어 접합면의 표면상태에 충분히 둔감하다는 장점을 가질 수 있다. 그림 1의 (b)는 개념도 (a)를 구현하기 위한 제작 공정을 보여준다. 버섯 모양의 구조물을 형성하는 공정과 측벽에 UBM을 선택적으로 형성하는 공정이 핵심 공정이며 이외의 접합 공정은 기존의 방법과 달리 매우 간단하게 완성시킬 수 있다. 본 논문에서는 기본적으로 제안된 방법으로 구현되는 실장결과와 그 기본적인 기계적 강도, 기밀 특성을 살펴 보았다. 그리고 RF 소자의 실장에 있어서 제안된 방법에 의한 전기적 연결의 기초 결과에 대해서 논의한다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.138-141
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• 2000

공정제어시스템을 위한 제어기로써 현재까지는 PID 제어기가 보편화되어 적용되어 왔으나 비선형 시스템이나 복잡한 시스템 제어를 위해서는 목표치 추종특성이 우수하며 환경이나 공정 파라미터변화에 둔감하여 외란에 대한 영향이 적은 제어기가 요구된다. PID 제어기로는 이러한 목적을 달성하는 데에 한계가 있기 때문에 이를 해결하기 위한 연구들이 활발히 수행되어 목표치 추종성능과 외란 억제를 동시에 만족토록 하는 다양한 2자유도 PID 제어시스템들이 제안되었고, 본 연구에서는 먼저 현재까지 제안된 2자유도 PID 제어시스템들 중 제어성능이 가장 우수한 것으로 나타난 목표치 필터형 2자유도 PID 제어시스템(Target Value Filter Type 2-DOF PID Control System: 이하 TVF-2DOF) [2]보다 우수한 2자유도PID 제어시스템을 제안하고, 이를 바탕으로 2자유도 선행필터(Pre-Filter)부분에 지능제어기법의 하나인 퍼지로직을 적용함으로써 PID 제어기의 장점과 퍼지로직의 장점을 동시에 활용하는 지능형 튜닝(Tuning)기법에 관한 연구를 수행하였고, 지능형 시스템이 2자유도 PID 제어시스템들보다 목표치 추종 성능 및 외란억제효과가 우수하다는 사실을 컴퓨터 시뮬레이션을 통해 입증하였다. 시스템으로는 유량 제어 밸브가 사용되었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1027-1035
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• 2016

In this paper, the method to miniaturize the radiating element of a VHF-band active electronically scanned array is proposed. The length of the proposed dipole having trapezoidal shape structure is miniaturized using meander line while the performance degradation is minimized. The grid reflector is used to improve the antenna directivity and insensitivity due to the outer environment. In addition, the antenna is designed to take into account for array application. The fabricated antenna has a 9.1 % fractional bandwidth for the voltage standing wave ratio(VSWR) 2:1 and the maximum gain of 4.24 dBi. The front-to-back ratio(FBR) is larger than 15 dB.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.6-11
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• 2006

This paper describes the novel control techniques design of VSC(Voltage Sag Corrector) for the purpose of power line quality enhancement. A fast detecting technique of voltage sag is implemented through the detection of instantaneous value on synchronous rotating dq-reference frame. The first order digital filter is added in the detection algorithm to protect the insensitive characteristics against the noise. The relationship between the total detection time and cut-off frequency of the filter is described. The size of the capacitor bank used as the energy storage element is designed from the point of view of input/output energy with circuit analysis. Finally, the validity of the proposed scheme is proven through the simulated results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1289-1294
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• 2010

In this paper, a new discrete integral static output feedback variable structure controller based on the a new integral dynamic-type sliding surface and output feedback discrete version of the disturbance observer is suggested for the control of uncertain linear systems. The reaching phase is completely removed by introducing a new proposed integral dynamic-type sliding surface. The output feedback discrete version of disturbance observer is presented for effective compensation of uncertainties and disturbance. A corresponding control with disturbance compensation is selected to guarantee the quasi sliding mode on the predetermined integral dynamic-type sliding surface for guaranteeing the designed output in the integral dynamic-type sliding surface from any initial condition for all the parameter variations and disturbances. Using discrete Lyapunov function, the closed loop stability and the existence condition of the quasi sliding mode is proved. Finally, an illustrative example is presented to show the effectiveness of the algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.425-431
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• 2010

This paper proposes a new adaptive speed controller for the speed control of a surface-permanent magnet synchronous motor. The proposed adaptive controller is very insensitive to model parameter and load torque variations since it does not require any accurate information on the motor parameter and load torque values. Moreover, the stability of the proposed control system is analytically proven. To verify the effectiveness of the proposed adaptive speed controller, simulation and experimental results are shown under motor parameter and load torque variations. It is clearly validated that the proposed speed regulator can precisely control the speed of permanent magnet synchronous motors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2541-2551
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• 1996

Human visual systems are sensitive to noise on the flat intensity area. But it becomes less sensitive on the edge area. Recently, many types of spatially adaptive image restoration methods have been proposed, which employ the above mentioned huan visual characteristics. The present paper presents an adaptive image restoration method, which increases sharpness of the edge region, and smooths noise on the flat intensity area. For edge detection, the proposed method uses the visibility function based on the local variance on each pixel. And it adaptively changes the regularization parameter. More specifically, the image to be restored is divided into a number of steps from the flat area to the edge regio, and then restored by using the finite impulse response constrained least squares filter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.4
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• pp.147-157
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• 1987

Five finite difference schemes (explicit, Bresler, implicit, upstream, and Chaudhari scheme) for the convective dispersion model are analyzed numerically to investigate their characteristics and applicabilities. Camparative study results show that the conditionally stable Chaudhari scheme has the smallest numerical dispersion and that the unconditionally stable Bresler scheme has the overshooting in regions of oscillation. Explicit scheme is the most accurate for a dispersion-dominated flow whereas Chaudhari scheme is for a convection-dominated flow. The computation time (CPU) is the shortest for the explicit or Chaudhari scheme with the same order of magnitude and is always the longest for the Bresler scheme.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.117-125
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• 2011

In this paper, it was segmented the face color distribution using YCbCr color model, which is one of the feature-based methods, and preprocessing stage was to be insensitive to the sensitivity for light which is one of the disadvantages for the feature-based methods by the quantization. In addition, it has raised the accuracy of image synthesis with characteristics which is selected the object of the most same image as the shape of pattern using rough set. In this paper, the detection rates of the proposed face detection algorithm was confirmed to be better about 2~3% than the conventional algorithms regardless of the size and direction on the various faces by simulation.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.2
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• pp.17-28
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• 2002

Recently, the study on non-linear equalization, self-recovering equalization using the neural Network structure or Fuzzy logic, is lively in progress. In this thesis, if the value of error difference is large, coefficient adaptation rate is bigger, and if being small, it is smaller. We proposed the new FSG(Fuzzy Stochastic Gradient)/CMA algorithm combining TS(Tagaki-Sugeno) fuzzy model having fast convergence rate and low mean square error(MSE) and CMA(Constant Modulus Algorithm) which is prone to ISI and insensitive to phase alteration. As a simulation result of the designed channel adaptive equalizer using the proposed FSG/CMA algorithm, it is shown that SNR is improved about 3.5dB comparing to the conventional algorithm.