• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.81-98
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• 2002

This paper documents the development of a bi-objective(minimizing delays and Queue lengths) cycle-free signal timing length model using Genetic Algorithm. The model was embodied using MATLAB. the language of technical computing. A special feature of this model is its ability to concurrently manage delays and queue lengths of turning movement concurrently. The model produces a cycle-free signal timing(cycles and green times) for each intersection on the cycle basis. Appropriate offsets could be also accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of four intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing delays and queue lengths of turning movements.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2639-2641
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• 2003

유전자 알고리즘은 다윈의 자연선택설과 유전자의 진화 개념을 이용한 적응 탐색 알고리즘으로 적용하고자 하는 문제의 매개 변수를 유전자와 비슷한 데이터 구조로 부호화하고, 유전 연산자를 이용하여 문제의 해답을 찾는 알고리즘이다. 최근 유전자 알고리즘은 이러한 복수개의 목적 함수를 최적화 하기 위한 다중 최적화 문제를 위한 최적화 기술로서의 관심이 크게 다루어지고 있으며 전송 문제, 생산 공정 문제 계획 등과 같은 다목적 함수를 다루는 많은 응용 부분에 대해 적용되고 있다. 본 논문에서는 기본적인 다중 목적 함수용 예와 Gen과 Kim이 제안한 네트워크 신뢰도를 고려한 연결 비용과 메시지 지연을 고려한 이중 구속 통신망 설계 문제를 가지고 가중치 합과 여러 가지 파레토 방법들을 비교하고 연구 검토 하고자 한다.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.347-358
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• 2021

The objective of this study is to optimize the shape of doubly curved surface where a conformal array is equipped. That surface is modeled with a double-ellipsoid solid controlled by four parameters. By analyzing the performance of the conformal array beams with the beam pattern synthesis, two design parameters are determined. Then, we define the weighted object function which is formulated as the sum of sharp indexes for directivity index, the elevation resolution, and the bearing resolution. The direct calculation on all grids is used to evaluate the weighted object function and seek the optimal value of two design parameters when the weightings are given. In the simulation, four kinds of weighting cases are respectively applied to evaluate the weighted object function. The optimal shapes of double-ellipsoid solid are shown in each case. Especially, when the uniform weightings are used, the double-ellipsoid solid with more smooth surface is obtained.

• Journal of the Korean Society of Visualization
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• v.22 no.3
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• pp.29-36
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• 2024

Topology optimization is vital in the conceptual design of various functional devices. While for thermal fluid problems, it is challenging to manage the trade-off between maximizing heat exchange and minimizing power consumption. This paper studies the individual, summation, and logarithmic summations of two conflicting objective functions in a self-developed topology optimization program for a liquid-cooled cold plate design problem. The optimized results show that the logarithmic summations provide good convergence toward the dual-objective numerical oscillations, generating smooth and continuous channel layouts. Meanwhile, it can be extended to customized layouts under the control of weighted factors. A comparison study is conducted with a conventional parallel-cooling cold plate design to validate the optimized design. Higher heat transfer coefficients and lower pressure drop are observed from the simulation results, thereby highlighting the superiority of the optimized design.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.175-180
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• 2010

In this paper, we have investigated ultrahigh frequency nano-mechanical resonators, made of DWCNTs with various wall lengths, via classical molecular dynamics simulations. We have aimed our analysis on the frequency variations of these resonators with the DWCNT wall lengths. The results show that the variations can be well fitted by either the Pearson VII function when the resonant frequency of normalized by its maximum frequency is plotted as a function of the inner/outer wall length ratio L5/L10 for different values of the outer wall length L10, and the Gauss distribution function when the resonant frequency of normalized by its maximum frequency is plotted as a function of the outer/inner wall length ratio for different values of the inner wall length.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.21-29
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• 2015

This paper proposes a novel two-tier optimization approach for decision making in many-objective problems. Because the Pareto-optimal solution ratio increases exponentially with an increasing number of objectives, simply finding the Pareto-optimal solutions is not sufficient for decision making in many-objective problems. In other words, it is necessary to discriminate the more preferable solutions from the other solutions. In the proposed approach, user preference-oriented as well as diverse Pareto-optimal solutions can be obtained as candidate solutions by introducing an additional tier of optimization. The second tier of optimization employs the corresponding secondary objectives, global evaluation and crowding distance, which were proposed in previous works, to represent the users preference to a solution and the crowdedness around a solution, respectively. To demonstrate the effectiveness of the proposed approach, decision making for some benchmark functions is conducted, and the outcomes with and without the proposed approach are compared. The experimental results demonstrate that the decisions are successfully made with consideration of the users preference through the proposed approach.

• Proceedings of the Korean Statistical Society Conference
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• 2003.10a
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• pp.331-334
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• 2003

마이크로 어레이(microarray)실험에서 표준화(normalization)는 유전자의 발현수준에 영향을 미치는 여러 기술적인 변인을 제거하는 과정이다. cDNA microarray normalization에 있어 여러 방법이 제안되었지만, 이중 print-tip 효과가 존재할 때 사용되는 방법으로 print-tip lowess normalization이 대표적으로 사용된다. normalization에 사용되는 lowess 함수는 데이터의 특성에 따라 window width를 정해야만 연구의 목적에 맞는 결과를 도출할 수 있다. 본 논문에서는 각각의 tip에서 최적의 window width를 계산하는 절차를 논의하였다. 또한 이의 결과와 기존의 같은 window width를 사용하는 print-tip lowess normalization 결과와 비교 평가하여 normalization의 기본 원칙에 대한 타당성을 확인하였다.

• Communications of Mathematical Education
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• v.20 no.1 s.25
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• pp.61-73
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• 2006

Studying functions is the fundamental that makes people understand complicate social events by using mathematical symbol system. But there are not enough program design and Teaching-learning strategy for mathematical-gifted student. So this research aim to design education program and teaching-learning strategy in functions area for mathematical-gifted student. 1 use real life-related problems to make students develop their problem-solving skill. And in this research I encourage students to study functions by grouping, discussion and presentation for self-directed teaming.

• Journal of the Korean School Mathematics Society
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• v.16 no.4
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• pp.883-898
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• 2013

The purpose of this study is to examine that high school students recognize mathematical situation when they are requested for changing identical mathematics situations into different situations. The results of the study are followings. First, percentage of correct answers to the questions of turning equal mathematical situation into function is higher than the one of turning equal mathematical situation into equation and inequality. As a result of individual interview for comprehensibility of the students on these relations, it is found that if degree goes up and there is different expressions of questionaries although mathematical situation is identical, it affects comprehensibility of the subjects. Second, we found that they cannot understand identical mathematics situations because they have trouble in drawing graph or applying to get the answer while many students understand a point of intersection on the graph as a correct answer. Third, As a result of individual interview for comprehensibility of the students on relation between equation, inequality and function, we found that students manage to get correct answer even without perfect comprehensibility on this relation.

• Computational Structural Engineering
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• v.7 no.4
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• pp.85-101
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• 1994

A family of variational principles governing the dynamics of laminated plate has been derived using a variationally consistent shear deformable discrete laminated plate theory with particular reference to finite element procedures. The theoretical basis for the derivation is Sandhu's generalized procedure for the variational formulation of linear coupled boundary value problem. As the bilinear mapping to write the operator matrix of the field equations in self-adjoint form, convolution product was employed. Boundary conditions, initial conditions and probable internal discontinuity were explicitly included in the governing functionals. Some interesting extensions and specializations of the general variational principle were presented, which can provide many different finite element formulations for the problem.