• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.624-627
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• 2004

본 연구는 동일한 병렬기계에서의 총 납기지연의 합을 최소화하는 일정계획 문제에 대해 다룬다. 이 문제는 Lenstra et al. (1977)에 의해 NP-hard로 알려져 있으며, 작업의 수와 기계의 수가 큰 현실적 문제에 대해 적절한 시간 내에 최적해를 찾는다는 것은 사실상 불가능하다. 따라서 본 연구에서는 이 문제를 해결하기 위하여 혼합형 유전 알고리즘(hybrid genetic algorithm)을 제안한다. 혼합형 유전 알고리즘에서는 임의로 발생시킨 모집단에 대해 먼저 유전 알고리즘(genetic algorithm)이 세대를 진행하며 해를 개선한다. 유전 알고리즘이 일정기간동안 더 이상 해를 개선하지 못하면, 부분탐색 알고리즘(local-search algorithm))이 유전 알고리즘의 모집단의 개체들에 대해 해의 개선을 시도한다. 즉, 부분 탐색 알고리즘은 모집단 속의 각각의 개체를 초기해로 하여 모집단 내의 개체 수만큼의 부분 최적해(local optimum)들을 구한다. 이렇게 구한 부분 최적해들로 새로운 모집단을 구성하면 다시 유전 알고리즘이 진행된다. 이 과정을 종료조건에 이를 때까지 번갈아가며 반복 수행한다. 본 연구에서 제안한 유전 알고리즘에서는 Bean(1994)이 제안한 Random key 방법으로 개체를 표현하였으며 Park(2000)이 제안한 3가지 교차 연산자들을 채용하였다. 부분탐색 알고리즘을 위해서는 쌍대교환(pair-wise interchange) 방법을 통해 이웃해를 생성하였다. 선행실험을 통하여 제안한 혼합형 유전알고리즘에서 사용하는 다양한 모수(parameter)값들을 최적화하였으며 알고리즘의 성능을 비교하기 위하여 기존의 알고리즘과도 비교실험을 수행하였다.복적인 지표가 채택되는 경우를 포함하고 있다. 셋째는 추상적이며 측정이 어려운 지표를 채택하고 있는 경우이다. 여기에는 지표에 대한 정확한 정의가 이루어져 있지 않아 피 평가자가 불필요하거나 과다한 평가 자료를 준비해야 하거나 평가자로 하여금 평가 시 혼돈을 유발할 가능성이 있거나, 또는 상위개념의 평가항목과 하위개념의 평가항목이 혼재되어 구분이 모호한 경우를 포함하고 있다. 바탕으로 '생태적 합리성'이라는 체계적인 지식교육을 거쳐서, '환경정의' 의식의 제고로 이어가고, 굵직한 '환경갈등'의 상황에서 뚜렷한 정치적 태도와 실천을 할 수 있는 '생태적 인간상'의 육성으로 나아갈 수 있어야 한다는 것이 필자의 생각이다. 이를 위해서는 어찌되었건 체험학습 영역에서는 환경현안에 대한 사회적 실천을 '교육 소재'로 삼을 수 있어야 하며, 교과학습 영역에서는 한국사회의 환경현안에 대한 정치경제적 접근을 외면하지 말고 교과서 저작의 소재로 삼을 수 있어야 하며, 이는 '환경관리주의'와 '녹색소비'에 머물러 있는 '환경 지식교육'과 실천을 한단계 진전시키는 작업으로 이어질 것이다. 이후 10년의 환경교육은 바로 '생태적 합리성'과 '환경정의'라는 두 '화두'에 터하여 세워져야 한다.배액에서 약해를 보였으나, 25% 야자지방산의 경우 50 ${\sim}$ 100배액 어디에서도 액해를 보이지 않았다. 별도로 적용한 시험에서, 토마토의 경우에도 25% 야자지방산 비누 50 ${\sim}$ 100배액 모두 약해를 발생하지 않았으나, 오이에서는 25% 야자지방산 비누 100배액에도 약해를 나타내었다. 12. 이상의 결과, 천연지방산을 이용하여 유기농업에 허용되는 각종의 살충비누를 제조할 수 있었으

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.10a
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• pp.12-19
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• 1993

In general, the line balancing problem is defined as of finding an assignment of the given jobs to the workstations under the precedence constraints given to the set of jobs. Usually, the objective is either minimizing the cycle time under the given number of workstations or minimizing the number of workstations under the given cycle time. In this paper, we present a new type of an assembly line balancing problem which occurs in an electronics company manufacturing home appliances. The main difference of the problem compared to the general line balancing problem lies in the structure of the precedence given to the set of jobs. In the problem, the set of jobs is partitioned into two disjoint subjects. One is called the set of fixed jobs and the other, the set of floating jobs. The fixed jobs should be processed in the linear order and some pair of the jobs should not be assigned to the same workstations. Whereas, to each floating job, a set of ranges is given. The range is given in terms of two fixed jobs and it means that the floating job can be processed after the first job is processed and before the second job is processed. There can be more than one range associated to a floating job. We present a procedure to find an approximate solution to the problem. The procedure consists of two major parts. One is to find the assignment of the floating jobs under the given (feasible) assignment of the fixed jobs. The problem can be viewed as a constrained bin packing problem. The other is to find the assignment of the whole jobs under the given linear precedence on the set of the floating jobs. First problem is NP-hard and we devise a heuristic procedure to the problem based on the transportation problem and matching problem. The second problem can be solved in polynomial time by the shortest path method. The algorithm works in iterative manner. One step is composed of two phases. In the first phase, we solve the constrained bin packing problem. In the second phase, the shortest path problem is solved using the phase 1 result. The result of the phase 2 is used as an input to the phase 1 problem at the next step. We test the proposed algorithm on the set of real data found in the washing machine assembly line.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2006.05a
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• pp.95-108
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• 2006

Because of rapid expansion of third party logistics, fierce competition in the transportation industry, and the diversification and globalization of transportation channels, an effective transportation planning by means of multimodal transport is badly needed. Accordingly, this study aims to suggest an optimal transport algorithm for the multimodal transport in the international logistics. Cargoes and stopovers can be changed numerously according to the change of transportation modes, thus being a NP-hard problem. As a solution for this problem, first of all, we have applied a pruning algorithm to simplify it, suggesting a heuristic algorithm for constrained shortest path problem to find out a feasible area with an effective time range and effective cost range, which has been applied to the Label Setting Algorithm, consequently leading to multiple Pareto optimal solutions. Also, in order to test the efficiency of the algorithm for constrained shortest path problem, this paper has applied it to the actual transportation path from Busan port of Korea to Rotterdam port of Netherlands.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.16-30
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• 2023

As the concept of metaverse has received great attention, interest in metaverse related to landscape architecture is also increasing. The aim of this research is to understand the potential and tasks of applying metaverse in the field of landscape architecture by analyzing the user experience of a metaverse platform. The object of the research is Meta-Everland built in the Roblox platform, which has the most users among landscape architectural metaverses in Korea. NPS of 30 users who have been to Everalnd was investigated after using Meta-Everland with interviews. NPS before the metaverse experience was -16 and NPS after the experience was -24. This result means that the promotion level was lowered after the experience of the metaverse. There were three causes of lowered NPS: lack of users, low-quality graphics and interface, and lack of content. The factor of lack of users was the result of the other two problems. The factor of low technical quality is hard to be improved in a short period of time. Therefore, the main task to improve the metaverse is developing better metaverse content related to landscape architecture. It is more appropriate to develop metaverse-specific content rather than improve reality issues. Applying AR and VR devices, enhancing communication function, and developing potential as a simulation device are needed to be considered.

• The Korean Journal of Air & Space Law and Policy
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• v.25 no.1
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• pp.205-236
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• 2010

This article deals with international space law for the environmental protection in outer space especially for space debris arising from space activities. After studying 1967 Outer Space Treaty, 1968 Rescue Agreement, 1972 Liability Convention, 1975 Registration Convention and 1979 Moon Agreement, we could find few provisions dealing with space environment in those treaties. During the earlier stages of the space age, which began in the late 1950s, the focus of international law makers was the establishment of the basic rules of space law governing the states' activities in outer space. Consequently the environmental issues and the risks that might arise from the generation of the space debris did not receive priority attention within the context of the development international space law. Although the phrases such as 'harmful contamination', 'harmful interference', 'disruption of the environment', 'adverse changes in the environment' and 'harmfully affecting' in relation to space environment were used in 1967 Outer Space Treaty and 1979 Moon Agreement, their true meaning was not definitely settled. Although 1972 Liability Convention deals with compensation, whether the space object covers space debris is unclear despite the case of Cosmos 954. In this respect international lawyers suggest the amendment of the space treaties and new space treaty covering the space environmental problems including the space debris. The resolutions, guidelines and draft convention are also studied to deal with space environment and space debris. In 1992 the General Assembly of the United Nations passed resolution 47/68 titled "Principles Relevant to the Use of Nuclear Power Sources in Outer Space" for the NPS use in outer space. The Inter-Agency Space Debris Coordination Committee; IADC) issued some guidelines for the space debris which were the basis of "the UN Space Debris Mitigation Guidelines" approved by COPUOS in its 527th meeting. In 1994 the 66th conference of ILA adopted "International Instrument on the Protection of the Environment from Damage Caused by Space Debris". Although those resolutions, guidelines and draft convention are not binding states, there are some provisions which have a fundamentally norm-creating character and softs laws.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.2
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• pp.469-497
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• 2015

In 2009 Iridium 33, a satellite owned by the American Iridium Communications Inc. and Kosmos-2251, a satellite owned by the Russian Space Forces, collided at a speed of 42,120 km/h and an altitude of 789 kilometers above the Taymyr Peninsula in Siberia. NASA estimated that the satellite collision had created approximately 1,000 pieces of debris larger than 10 centimeters, in addition to many smaller ones. By July 2011, the U.S. Space Surveillance Network(SSN) had catalogued over 2,000 large debris fragments. On January 11, 2007 China conducted a test on its anti-satellite missile. A Chinese weather satellite, the FY-1C polar orbit satellite, was destroyed by the missile that was launched using a multistage solid-fuel. The test was unprecedented for having created a record amount of debris. At least 2,317 pieces of trackable size (i.e. of golf ball size or larger) and an estimated 150,000 particles were generated as a result. As far as the Space Treaties such as 1967 Outer Space Treaty, 1968 Rescue Agreement, 1972 Liability Convention, 1975 Registration Convention and 1979 Moon Agreement are concerned, few provisions addressing the space environment and debris in space can be found. In the early years of space exploration dating back to the late 1950s, the focus of international law was on the establishment of a basic set of rules on the activities undertaken by various states in outer space.. Consequently environmental issues, including those of space debris, did not receive the priority they deserve when international space law was originally drafted. As shown in the case of the 1978 "Cosmos 954 Incident" between Canada and USSR, the two parties settled it by the memorandum between two nations not by the Space Treaties to which they are parties. In 1994 the 66th conference of International Law Association(ILA) adopted "International Instrument on the Protection of the Environment from Damage Caused by Space Debris". The Inter-Agency Space Debris Coordination Committee(IADC) issued some guidelines for the space debris which were the basis of "the UN Space Debris Mitigation Guidelines" which had been approved by the Committee on the Peaceful Uses of Outer Space(COPUOS) in its 527th meeting. On December 21 2007 this guideline was approved by UNGA Resolution 62/217. The EU has proposed an "International Code of Conduct for Outer Space Activities" as a transparency and confidence-building measure. It was only in 2010 that the Scientific and Technical Subcommittee began considering as an agenda item the long-term sustainability of outer space. A Working Group on the Long-term Sustainability of Outer Space Activities was established, the objectives of which include identifying areas of concern for the long-term sustainability of outer space activities, proposing measures that could enhance sustainability, and producing voluntary guidelines to reduce risks to long-term sustainability. By this effort "Guidelines on the Long-term Sustainability of Outer Space Activities" are being under consideration. In the case of "Declaration of Legal Principles Governing the Activities of States in the Exp1oration and Use of Outer Space" adopted by UNGA Resolution 1962(XVIII), December 13 1963, the 9 principles proclaimed in that Declaration, although all of them incorporated in the Space Treaties, could be regarded as customary international law binding all states considering the time and opinio juris by the responses of the world. Although the soft law such as resolutions, guidelines are not binding law, there are some provisions which have a fundamentally norm-creating character and customary international law. In November 12 1974 UN General Assembly recalled through a Resolution 3232(XXIX) "Review of the role of International Court of Justice" that the development of international law may be reflected, inter alia, by the declarations and resolutions of the General Assembly which may to that extend be taken into consideration by the judgements of the International Court of Justice. We are expecting COPUOS which gave birth 5 Space Treaties that it could give us binding space debris mitigation measures to be implemented based on space debris mitigation soft law in the near future.