• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.405-405
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• 2012

InSb는 높은 전자이동도와 낮은 밴드갭을 가지고 있어 저전력 고효율의 고주파소자 및 비선형 광소자에 적합한 물질이다. 특히 InSb 기반 소자들은 전자-포논효과의 영향을 덜 받는 저온에서 고감도 소자로도 사용되고 있는데, 소자의 최적합 설계와 제작시의 실시간 성장제어를 위해서는 넓은 온도범위에서의 InSb의 광물성이 필요하다. 분광타원편광분석법(ellipsometry)은 물질의 광특성인 유전율 함수를 정확하게 측정 할 수 있은 기술로써, InSb 에 대한 유전율 함수는 많은 연구를 통해 잘 알려져 있다. 그러나, 온도변화에 대한 연구로는 100-700 K, 1.2-5.6 eV의 제한된 온도와 분광영역에서만 이루어졌다. 본 연구에서는 보다 확장된 온도범위(25-686 K), 광역 에너지 범위 (0.74-6.5 eV)에서 분광타원편광분석 연구를 수행하였다. 그 결과 저온에서의 전자-포논 효과의 감소로 인한 청색천이와 보다 명확한 전자전이점들의 값을 얻었다. 특히, 100 K 까지의 이전 연구에서는 구분할 수 없었던 $E_2'$ 전이점을 본 연구의 25 K 의 유전율 함수에서 명확히 구분할 수 있었고, 고에너지 영역의 $E_1'+{\Delta}_1+{\Delta}_1'$ 전이점의 온도의존성을 처음으로 연구하였다. 본 연구의 결과는 InSb 를 기반으로 한 광전자 소자의 개발 및 적용분야와 밴드갭 엔지니어링 분야에 많은 도움이 될 것으로 예상한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.525-534
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• 2005

This paper proposes the architecture and the methods of security network management for auto-configuration of security systems by extending the existing policy-based network management architecture. The architecture and the methods proposed in this paper enable a security management sewer to automatically decide the best-suited security policy to apply to a security system and the most effective and efficient security system to perform security policy rule, based on the role and capability information of security systems and the role and time information of security policy. For integrated control of network system and security system, this paper also proposes SNMP protocol based security network topology map generator. To show the excellence of the proposed architecture and methods, we simulate and evaluate the automatic response against attacks.

• Journal of KSNVE
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• v.5 no.2
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• pp.225-234
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• 1995

In this study, first, transformation process of damping ratios, whose are evaluated in active control analysis, into damping matrix resulting from installed viscous dampers is illustrated. Then, a method is followed to maximize the effect of response reduction, which leads to optimum locations and size of viscous dampers using sensitivity analysis. Highly coupled nonlinearity between damping ratios and dampers makes it hard to find the optimal size of dampers. Therefore, the nonlinearity is transformed to linear problem with small increments of damping ratios and the size of dampers can be found. However, there are many cases for the size of dampers satisfying the small increment of damping ratios, so it is necessary to select minimum size using optimization technique. To determine optimum locations of dampers, dampers are assumed to be installed between the different stories and their locations are selected corresponding corresponding to the degree of damping size. Numerical examples for the frame structure and the shear wall structure show that optimum locations and size of dampers are different form each other depending on the characteristics of modal responses of the structures. The proposed method in this study can be applied to get optimum locations of active controller in the active control.

• Aerospace Engineering and Technology
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• v.5 no.2
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• pp.195-204
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• 2006

A linear acoustic analysis has been performed to elucidate damping characteristics of acoustic cavities in a liquid rocket combustor. Results have shown that resonant frequencies of acoustic cavity obtained by classical theoretic approach and by the present linear analysis are somewhat different with each other. This difference is attributed to the limitation of the simplified classical theory. To quantify the damping characteristics, acoustic impedance has been introduced and resultant absorption coefficient and conductance have been evaluated. Satisfactory agreement has been achieved with previous experiment. Finally the design procedure for an optimal tuning of acoustic cavity has been established.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.9-11
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• 2014

As Daecheon beach, which is the study area, has problem of erosion and loss of most beach under the extraordinary wave during the typhoon event, it is necessary to apply erosion control measures for short term impact. Therefore, we analyzed the status and reason of the erosion by field survey, collection of hydraulic model test, and numerical model experiment. For the erosion control measure, we adopted beach feeding and submerged reef method available at that site among various counter measures. Numerical analyses were made for both beach feeding only and beach feeding with submerged reefs and these were compared with the present status to find out the optimum design and to contribute for preparing a long term plan of beach loss protection.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1129-1132
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• 2000

최근 인터넷 수요의 증가로 통신망에서 음성, 영상 및 데이터(data)를 복합적으로 지원할 수 있는 멀티서비스(multiservice)의 교환 기술이 필수적이다. 또한 망 사업자들이 여러 벤더(vendor)들로부터 최적의 장비를 선택하여 망을 구축할 수 있도록 통신 장비들의 상호 운용성을 지원하는 개방형 구조의 망 및 스위치 시스템(switch system)을 정의하는 작업이 필요하다. 페트리 넷(Petri Nets)은 시스템(system)을 분석하기 위한 도구로서, 시스템은 페트리 넷 이론에 의해 시스템의 수학적 표현인 페트리 넷으로 설계될 수 있다. CPN(Colored Petri Nets)은 페트리넷의 확장형으로서, 토근(token)에 칼라를 부여하여 다양한 특성을 지닌 시스템을 표현하기에 적합하다. Design/CPN은 CPN의 사용을 지원하는 소프트웨어 패키지(software package)이다. 본 논문에서는 개방형 멀티서비스 교환 시스템의 핵심으로 스위치와 제어기(Controller) 사이의 표준 프로토콜인 GSMP(General Switch Management Protocol) 프로토콜을 Design/CPN 으로 변환하고, 이로부터 시험열을 생성한다.

• Journal of IKEEE
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• v.17 no.1
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• pp.36-43
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• 2013

This paper proposes a motion estimation algorithm with run-time adaptive workload control. It has optimized performance within limited hardware resources while guaranteeing hard realtime operation. It performs maximum searches within hard realtime constraints, since it determines search steps and workload adaptively. It reduces the hardware size to 1/4~1/400 of conventional algorithms, while its PSNR degradation is only 0.02~0.44 dB. It can be easily applied to most conventional fast algorithms, so it is useful to design realtime encoder chips.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1382-1387
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• 1999

This paper presents an optimal fuzzy power system stabilizer to damp out low frequency oscillation. So far fuzzy controllers have been applied to power system stabilizing controllers due to its excellent properties on the nonlinear systems. But the design process of fuzzy logic power system stabilizer requires empirical and heuristic knowledge of human experts as well as many trial-and-errors in general. This paper presents and optimal design method of the fuzzy logic stabilizer using the genetic algorithm. Non-symmetric membership functions are optimally tuned over an evaluation function. The present inputs of fuzzy stabilizer are torque angle error and the change of torque angle error without loss of generality. The coding method used in this paper is concatenated binary mapping. Each linguistic fuzzy variable, defined as the peak of a membership function, is assigned by the mapping from a minimum value to a maximum value using eight bits. The tournament selection and the elitism are used to keep the worthy individuals in the next generation. The proposed system is applied to the one-machine infinite-bus model of a power system, and the results showed a promising possibility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.407-415
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• 2011

In this study, we propose the design of optimized fuzzy controller for the rotary inverted pendulum system by using differential evolution algorithm. The structure of the differential evolution algorithm has a simple structure and its convergence to optimal values is superb in comparison to other optimization algorithms. Also the differential evolution algorithm is easier to use because it have simpler mathematical operators and have much less computational time when compared with other optimization algorithms. The rotary inverted pendulum system is nonlinear and has a unstable motion. The objective is to control the position of the rotating arm and to make the pendulum to maintain the unstable equilibrium point at vertical position. The output performance of the proposed fuzzy controller is considered from the viewpoint of performance criteria such as overshoot, steady-state error, and settling time through simulation and practical experiment. From the result of both simulation and practical experiment, we evaluate and analyze the performance of the proposed optimal fuzzy controller from the comparison between PGAs and differential evolution algorithms. Also we show the superiority of the output performance as well as the characteristic of differential evolution algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.401-408
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• 1998

Recently there comes out various applications on real time control, audio/video conference, medical image and so on. These applications request certain Quality of Service(QoS) to their underlying communication subsystem. In these cases those communication subsystems should provide real time communication service on their QoS request as well as good performance to maintain best effort traffic. In this paper firstly we briefly look over bandwidth, traffic parameters on point to point network secondly we analyze on real time channel and propose design factors in real time channel protocol for multimedia applications.