• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.796-798
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• 2005

본 연구에서는 엔트로피 이론을 사용하여 ICA(Independent Component Analysis) 점수함수를 생성하는 새로운 밀도추정자(Density Estimator)를 제안한다. 원 신호에 대한 밀도함수의 추정은 적당한 점수함수를 생성하기 위해 필요하고, 미분 가능한 밀도함수인 커널을 이용한 밀도추정법(Kernel Density Estimation)을 이용하여 점수함수를 생성하였다. 보다 빠른 점수함수의 생성을 위해서 식의 형태를 convolution 형태로 표현하였으며, ICA 학습을 위해서 결합엔트로피를 최대화(Joint Entropy Maximization)하는 방향으로 커널의 폭을 학습하였다. 이를 위해서 기울기 강하법(Gradient descent method)를 사용하였으며, 이러한 제약 사항은 새로운 밀도 추정자를 설계하기 위한 기본적인 개념을 나타낸다. 실험결과, 커널의 폭을 담당하는 smoothing parameters들이 일정한 값으로 학습함을 알 수 있었다.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.84-88
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• 2004

Accident of small and medium-sized construction sites happens much than large-sized construction sites. The safety consulting for accident prevention of construction sites has been launched in 1995. This research probed latency accident of small and medium-sized construction sites. By method, we used that result data of safety consulting for accident prevention of small and medium-sized construction sites. As a result a fall was examined by the most latency accident factor. In this study, a fall and electric shock, descent, fall down in ground, a fire was examined weighty accident factor of small and medium-sized construction sites.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.9
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• pp.2284-2298
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• 2013

In this paper, a fast and efficient signal reconstruction algorithm for solving the basis pursuit (BP) problem in compressed sensing (CS) is proposed. This fast linearized Bregman method (FLBM), which is inspired by the fast method of Beck et al., is based on the fact that the linearized Bregman method (LBM) is equivalent to a gradient descent method when applied to a certain formulation. The LBM requires $O(1/{\varepsilon})$ iterations to obtain an ${\varepsilon}$-optimal solution while the FLBM reduces this iteration complexity to $O(1/\sqrt{\varepsilon})$ and requiring almost the same computational effort on each iteration. Our experimental results show that the FLBM can be faster than some other existing signal reconstruction methods.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.4
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• pp.228-234
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• 2005

In this paper, we proposed a self tuning adaptive fuzzy sliding control algorithms using gadient descent method to reduce chattering phenomenon which is viewed in variable control system. In design of FLC, fuzzy control rules are obtained from expert's experience and intuition and it is very difficult to obtain them. We proposed an adaptive algorithm which is automatically updated by consequence part parameter of control rules in order to reduce chattering phenomenon and simultaneously to satisfy the sliding mode condition. The proposed algorithm has the characteristics which are viewed in conventional VSC, e.g. insensitivity to a class of disturbance, parameter variations and uncertainties in the sliding mode. To demonstrate its performance, the proposed control algorithm is applied to an inverted pendulum system. The results show that both alleviation of chattering and performance are achieved.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.461-465
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• 2006

This paper presents a useful and simple method to design the passive skimming system for homogeneous permanent magnets based on numerical optimization. To simulate the effects of manufacturing and assembling tolerances, the actual geometrical parameter of the magnet with a derivation is suggested. Then, the optimal design model oi a passive shim system is set up to correct the derivative of field homogeneity. The numbers, sizes and locations of the passive shims are optimized by the steepest descent algorithm combined with design sensitivity analysis. Two implementations show that the proposed method can achieve the required homogeneity of the field with the minimum quantity of ferromagnetics.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2034-2036
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• 2002

In this paper, we propose the modeling of a chaotic nonlinear system using wavelet neural networks. In our modeling, we used the parameter adjusting method as the training method of a wavelet neural network. The difference between the actual output of a nonlinear chaotic system and that of a wavelet neural network adjusts the parameters of a wavelet neural network using the gradient-descent method. To verify the efficiency of this paper, we perform the simulation using Duffing system, which is a representative continuous time chaotic nonlinear system.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2228-2230
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• 2002

The research presented in this paper focuses on a method for the detection of High Impedance Fault(HIF). The method will use the Lifting and neural network system. HIF on the multi-grounded three-phase four-wires primary distribution power system cannot be detected effectively by existing over current sensing devices. These paper describes the application of lifting scheme to the various HIF data. These data were measured in actual 22.9kV distribution system. Wavelet transform analysis gives the frequency and time-scale information. The neural network system as a fault detector was trained to discriminate HIF from the normal status by a gradient descent method. The proposed method performed very well by proving the right state when it was applied staged fault data and normal load mimics HIF, such as arc-welder.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.394-396
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• 1997

This paper describes RBF network controller based on fuzzy control rules for intelligent control of nonlinear systems. The proposed scheme is derived from the functional equivalence between RBF networks and fuzzy inference systems. The design procedure of the proposed scheme is realized by first transforming the fuzzy control rules into the parameters of RBF networks. The optimized RBF network controller is then performed through the gradient descent learning mechanism to an error function. The proposed method is rigorously tested using a nonlinear and unstable nonlinear system. Simulation is performed to demonstrate the feasibility and effectiveness of the proposed scheme.

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.705-707
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• 1997

An optimal tuning algorithm of scaling factors is presented in this paper to automatically improve the performance of fuzzy controller. Especially, fuzzy controller has determined an moderate Scaling factor through trial and error. The presented method estimates automatically the optimal values of I/O scaling factors, using modified steepest descent method and this optimal tuning is for nonlinear input/output scaling factors. Simulation results verify the validity of the presented method.

• 한국항공운항학회:학술대회논문집
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• 2015.11a
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• pp.68-77
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• 2015

점증하는 항공교통량의 원활한 수용과 안전한 항공기술 저변확대를 위하여 ICAO는 성능기반의 항공교통관리(ATM) 체계와 시스템을 Upgrade할 구체적 이행계획인 ASBU를 개정하고 체약국들의 수용을 촉구하고 있고, 우리나라는 ICAO의 5연임 이사국으로서 ASBU의 주요 Module에 대응하는 모든 Working Paper에 대하여 적극 수용한다는 입장이다. 본 논문은 ASBU의 PIA 4에 해당하는 CDO 및 관련 Module인 TBO의 개념을 살펴보고, 선도적으로 운용되고 있는 사례를 분석해 봄으로써 미래에 대응하는 방안을 찾고자 하였다. CDO는 새로운 장비와 시스템을 갖추지 않더라도 절차의 보완으로 개선할 수 있는 부문에 속하므로 우리나라의 운영 현황을 리뷰하고 그 영향에 대하여 정리해 보았다. 다만, 항공기 고도 강하 단계에서의 개선효과가 상승 또는 순항 단계에 비하여 효율성이 상대적으로 미미한 편이고, ATM 구분 상 기상 등의 외부 변수에 취약하여 효율성 연구에 접근하기 어려운 면이 있으나, 고밀도 공항의 특화된 CDO 기법 개발을 통하여 연료절감 및 탄소배출량 저감, 소음감소의 성과를 이룬 선진 사례를 들어 국내에 적용할 수 있는 방안에 대하여 장기적으로 연구하고자 한다.