• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.351-354
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• 1998

In this paper, electrical characteristics of an n-channel Si MOSFET with L$_{s}$=0.6.mu.m under optical illumination are charaterized on wafer. Energetic photons with .gamma.=830nm, hv=1.494eV, P$_{opt}$=300mW are injected near the drain junction, the most photoresponsive region in the device, via optical fiber. We observed significantly increased drain current and transconductance, which is considered to be useful for the implementation of OEICs on silicon substrate, under optical control with P$_{opt}$=300mW. Optical power-dependent physical mechanisms responsible for the variation of electrical characteristics under optical input are also reported.d.d.d.

• ETRI Journal
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• v.31 no.1
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• pp.68-70
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• 2009

In this letter, a parametric analysis of the Fresnel-field antenna measurement method is performed for a square aperture. As a result, the optimum number of Fresnel fields for one far-field point is guided as $M_{opt}=N_{opt}=D^2/{\lambda}R+5$, where D is the antenna diameter, ${\lambda}$ is the wavelength, and R is the distance between the source antenna and the antenna under test. For the aperture size 5 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 20, the tolerable distances for gain errors of 0.5 dB and 0.2 dB can be guided as $R_{0.5\;dB}$ ${\approx}$ $1.2Lx/{\lambda}$ and $R_{0.2\;dB}$ ${\approx}$ $2.0L_x/{\lambda}$, where $L_x$ is the lateral length of the square aperture. The tolerable distances for 20 ${\leq}$ $L_x/{\lambda}$ ${\leq}$ 200 are also proposed. This measurement guideline can be fully utilized when performing the Fresnel-field antenna measurement method.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.225-232
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• 2014

The traditional RAP (Redundancy Allocation Problem) of complex systems has considered only the redundancy of subsystem with homogeneous components. In this paper we extend it as a RAP of complex systems with heterogeneous components which is more flexible than the case of homogeneous components. We model this problem as a nonlinear integer programming problem, find its optimal solution by tabu search, and suggest an example of the efficient reliability design with heterogeneous components. In order to improve the quality of the solution of the tabu search, we suggest a modified tabu search to employ an adaptive procedure (1-opt or 2-opt exchange) to generate the efficient neighborhood solutions. Computational results show that our modified procedure obtains better solutions as the size of problem increases from 30 to 50, even though it requires rather more computing time. With some adjustment of the parameters of the proposed method, it can be applied to the optimal reliability designs of complex systems of ships.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.3
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• pp.47-61
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• 2007

This paper presents two elimination methods of subtours, which is obtained by applying the Out-of-Kilter algorithm to the sequential ordering problem (SOP) to produce a feasible solution for the SOP. Since the SOP is a kind of asymmetric traveling salesman problem (ATSP) with precedence constraints, we can apply the Out-of-Kilter algorithm to the SOP by relaxing the precedence constraints. Instead of patching subtours, both of two elimination methods construct a feasible solution of the SOP by using arcs constructing the subtours, and they improve solution by running 3-opt and 4-opt at each iteration. We also use a perturbation method. cost relaxation to explore a global solution. Six cases from two elimination methods are presented and their experimental results are compared to each other. The proposed algorithm found 32 best known solutions out of the 34 instances from the TSPLIB in a reasonable time.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.189-199
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• 2000

This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X$_{opt}$ to be 0.5 when optimum phase change temperatures are used. Otherwise X$_{opt}$ is determined differently as a function of given phase change temperatures.res.

• Journal of the Korea Safety Management & Science
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• v.13 no.3
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• pp.107-114
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• 2011

Traveling salesman problem is to minimize the total cost for a traveling salesman who wants to make a tour given finite number of cities along with the cost of travel between each pair them, visiting each cities exactly once before returning home. Traveling salesman problem is known to be NP-hard, and it needs a lot of computing time to get the optimal solution, so that heuristics are more frequently developed than optimal algorithms. This study suggests a hybrid parallel genetic algorithm(HPGA) for traveling salesman problem The suggested algorithm combines parallel genetic algorithm, nearest neighbor search, and 2-opt. The suggested algorithm has been tested on 7 problems in TSPLIB and compared the results of existing methods(heuristics, meta-heuristics, hybrid, and parallel). Experimental results shows that HPGA could obtain good solution in total travel distance minimization.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1078-1079
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• 2023

해양 분야에서의 정보기술 발전으로 선박 자율운항의 중요성이 증대되고 있다. 이에 선박 자율운항기술의 핵심인 경로 계획에는 그리드 기반 알고리즘이 주목을 받고 있다. 본 논문은 D* Lite 알고리즘을 선박자율운항에 적합하게 조정한 D* Opt 알고리즘을 소개하며, 기존 알고리즘과의 경로 비용 및 생성 시간을 비교 분석하여 성능을 확인한다. 이를 통해서 D* Opt 알고리즘이 선박 자율 운항경로 핵심기술로 응용 가능성과 기대효과를 제시한다.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.53-58
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• 1995

Examples of advanced digital electro-optic imaging systems for the satellite remote sensing applications are introduced including multispectral focal plane assembly for newly proposed 1-m spatial resolution capability.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.3
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• pp.4171-4183
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• 1976

This study is to investigate the effect of some physical properties of soil on the compaction. The compaction effect depends upon various factors such as soil type, moisture content, gradation and compaction energy. In this study, with steady compaction energy, the relationships between maximum dry density and moisture content, gradation and consistency were analyzed by soil types. Some results obtained in this study are summarized as follows 1. Generally, the coarser the grain size, the bigger is the maximum dry density and the smaller is the optimum moisture content and its moisture-dry denisty curve is relatively steep. The finner the grain size, the smaller is the max. dry density and the bigger is the opt. moisture content and its moisture-dry density curve is less steep. 2. The relationship between max. dry density (${\gamma}$dmax) and opt. moisture content, void ratio, clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation ${\gamma}$dmax =ao+a1X(a0>0, a1<0) 3. The relationship between opt. moisture content (Wopt) and clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation Wopt=a0+a1X(a0>0, al>0). 4. The fact that maximum dry density of the compacted soil is decreased with the increase of the optimum moisture content in any types of soil tested, and the fact that optimum moisture content can be positively correlated with clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil, lead to the conclusion that clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil are direct factors in reduction of the maximum dry density of engineering soil.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.1-6
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• 2002

When bilateral sagittal split ramus osteotomy or mandibular angle reduction are carried out, we have to consider the position of inferior alveolar nerve. For bone splitting or resection using a saw or an osteotome, the bucco-lingual position of the inferior alveolar nerve plays an important role in the preventing perioperative complications such as paresthesia or anesthesia. Because it is rare to find literatures concerning the mean anatomic position of the inferior alveolar nerve in Koreans, we investigated 30 patients who underwent to take CT and orthopantomogram for implant surgery, and evaluated the bucco-lingual position and vertical relationship of the inferior alveolar nerve at the mandible. The results showed that the distance between inferior alveolar nerve and buccal plate was the farthest at mandibular second molar ($7.1{\sim}7.4mm$) and the nearest at mandibular angle area ($4.4{\sim}4.8mm$). But it was no statistical relationship between the bucco-lingual postion of inferior alveolar nerve on the CT and its vertical position on the OPT. In conclusion, the results suggest that a careful surgical procedure is needed at the mandibular angle area to avoid a nerve damage and there are sufficient bone materials at the mandibular second molar are for bilateral sagittal split ramus osteotomy or mandibular angle reduction or plate fixation. And OPT is not usefull for the evaluation of a relative bucco-lingual position of inferior alveolar nerve in relation to its vertical postion on the OPT.