• Journal of Communications and Networks
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• v.14 no.6
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• pp.606-613
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• 2012

In a smart grid environment, data for the usage and control of power are transmitted over an Internet protocol (IP)-based network. This data contains very sensitive information about the user or energy service provider (ESP); hence, measures must be taken to prevent data manipulation. Mutual authentication between devices, which can prevent impersonation attacks by verifying the counterpart's identity, is a necessary process for secure communication. However, it is difficult to apply existing signature-based authentication in a smart grid system because smart meters, a component of such systems, are resource-constrained devices. In this paper, we consider a smart meter and propose an efficient mutual authentication protocol. The proposed protocol uses a matrix-based homomorphic hash that can decrease the amount of computations in a smart meter. To prove this, we analyze the protocol's security and performance.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.2
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• pp.83-89
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• 2001

This paper introduces a power flow model of SSSC for voltage stability analysis of power system installed with Static Synchronous Compensators. The SSSC model is obtained from the injection model of voltage source inverter by adding the condition that SSSC injection voltage is in quadrature with current of SSSC-installed branch. This model is incorporated into modified CPF algorithm to study effects of SSSC on the security-constrained interface flow limit. Determination of interface flow limit is simply briefed. In case study a 771-bus real system is used to show that interface flow limit can be improved by appropriate control of SSSC in terms of voltage stability.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.239-242
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• 2001

This paper presents a windows program package for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming(EP) and sequential quadratic programming(SQP). The objective functions are the minimization of generation fuel costs and system power losses. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. In OPF considering security, the outages are selected by contingency ranking method. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). The OPF package proposed is applied to 10 machines 39 buses model system.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.194-196
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• 2001

This paper presents a hybrid algorithm for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming (EP) and sequential quadratic programming (SQP). The objective functions are the minimization of generation fuel costs and system power losses. In OPF considering security, the outages are selected by contingency ranking method. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. The method proposed is applied to the modified IEEE 14buses model system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.267-270
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• 1996

In this paper, we present a new design method to implement autoassociative memories based on BSB neural networks. With a concrete mathematical model proposed after analyzing some new qualitative properties of autoassociative memories, we reinterpret design of autoassociative memories as a constrained optimization problem and use an evolution program as an optimal search tool to solve this. The proposed method satisfies many of the criteria used to evaluate the effectivencess of a given associative memory and has improvements with respect to correctness and performance. Comparing simulation results with other methods, we demonstrate the effectiveness of the proposed method.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.53-64
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• 2004

Repetition Strain Injury (RSI) is usually caused or aggravated by poor work processes and unsuitable working conditions - that involve repetitive or forceful movements or the maintenance of constrained or awkward postures. The condition is characterized by discomfort and persistent pain. There are three essential steps to eliminate or control hazards In workplace. Case and Demographic Characteristics for Work-related Injuries and illnesses Involving Days Away From Work, 2002. U.S' was examined. Causes of press operators' RSI were carpal tunnel syndrome(CTS), tendonitis, low back pain, and occupational stress. Recommendations for improvement of productivity are redesign of working conditions, exercise, prevent of RSI and avoiding stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1430-1437
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• 2005

It is very important to achieve a high reproducibility in the ultrasonic measurement of bone mineral density. In this study, we examined number of sampling waveform, control of temperature, diameter of region of interest as factors to improve reproducibility. We decided the optimal number of waveforms to be converted to frequency domain as period of 1. We have minimized the effects of variable temperature and constrained generation of micro bubble by keeping temperature within a range of $32\pm0.5^{\circ}C$ with a precise temperature controlling algorithm. We also found the optimal diameter of region of interest to be 13mm. In this paper, we demonstrated the improved reproducibility by controlling various factors affecting the ultrasonic measurement of bone mineral density.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.469-471
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• 1998

이논문은 입력과 상태변수에 제한조건이 있는 이산형 불확실 선형 시스템을 위한 강인한 이동구간 제어기를 제시한다. 모델 변수는 콘벡스 집합에 속하는 불확실성 성질을 갖는다. 제안된 이동구간 제어기는 터미널 가중치 행렬들과 입력과 상태변수의 제한조건을 가지는 최악의 일단계 목적함수의 최소화에 기초한다. 제안된 이동구간 제어기는 위의 불확실한 시스템을 일정한 터미널 가중치 행렬에 대한 행렬 부등식 조건하에서 안정화 시킬수 있다는 것을 보인다. 이 강인 이동구간 제어기는 기존의 무한 구간 강인 이동구간 제어기보다 같은 설계 조건하에서 보다 더 일반적인 구조와 더 큰 간으한 초기 상태 영역을 갖는다. 이 제시된 이동구간 제어기는 반한정 프로그래밍을 이용하여 얻어진다.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.405-409
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• 2013

In this paper, a unifying framework to evaluate the depth resolution of axially distributed image sensing (ADS) systems under fixed resource constraints is proposed. The proposed framework enables one to evaluate the system performance as a function of system parameters such as the number of cameras, the number of pixels, pixel size, and so on. The Monte Carlo simulations are carried out to evaluate ADS system performance as a function of system parameters. To the best of our knowledge, this is the first report on quantitative analysis of ADS systems under fixed resource constraints.

• Journal of Agricultural Extension & Community Development
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• v.3 no.1
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• pp.43-54
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• 1996

Citrus farming become one of highly potent area for the farmer s income in the Asia region. Because of its favorable taste and distinctive aroma, attractive color, and nutritional values, market demand has increased steadily along with the income increases in the region. However, realization of the potent have been constrained due to poor orchard management, frequent occurrences of pest and diseases, and a high cost in production besides of the market failures. Cutting down of production cost should be an operational goal to obtain mope profit where marketing structure has yet been underdeveloped. The objective of this study was to provide a comparative information to those program efforts of searching comparative advantage in production. For the three countries, reduction of labor cost by reduction of chemical application frequency was recommended while pursuing further mechanization in those operation such as in pruning, harvesting and pest control. Adoption of the IPM (integrated pest management) will be useful to reduce the number of spraying chemicals with changed knowledge and attitude of the farmers.