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        검색결과 19

        1.
        2019.12 KCI 등재 서비스 종료(열람 제한)
        해양석유 생산은 예기치 못한 유가 하락과 글로벌 석유물류의 변화로 인한 여러 가지 어려움에 직면하고 있다. 이 연구는 불확실성하의 해양석유생산 최적화를 위한 추계적 모형을 제시한다. 제시된 추계적 모형은 강인한 최적화 모형과 리코스 제한 최적화 모형을 사용하고 리코스 이익 변동의 척도로 하위부분평균을 사용한다. 제안된 모형을 바탕으로 불확실성 하의 원유의 가격과 수요에 관한 시나리 오 기반의 자료를 사용하여 수행한 계산실험 및 결과를 검토하여 보고하였다. 이 연구는 불학실성 하에서 위험을 고려한 해양석유생산 문제에 대한 의사결정에 유의하게 적용될 수 있을 것이다.
        2.
        2015.08 KCI 등재 서비스 종료(열람 제한)
        해양 석유 생산은 ‘해양‘이라는 특성에 기인하는 여러 가지 변수를 동반하면서 막대한 비용과 시간을 필요로 한다. 모든 관련된 프 로세스는 인명, 환경 그리고 재산의 손실을 줄이기 위한 치밀한 일련의 계획에 의하여 통제된다. 이 논문은 해양 석유 생산 및 수송의 최적화 문제를 다룬다. 문제 영역의 범위를 정의하기 위해 해양 석유 생산 및 수송 네트워크를 제시하고 그 문제를 해결하기 위한 혼합정수계획모형 을 구축하였다. 제안된 최적화 모형의 타당성을 확인하기 위해 가상의 해양 유전과 수요 시장을 바탕으로 MS Office Excel의 해찾기를 이용 하여 계산실험들을 수행하였다. 해양 석유 생산 및 수송 네트워크 하위 흐름은 해양 유전에서 생산된 원유를 수요 시장으로 배분하는 해사수 송문제가 된다. 이 해사수송문제를 해결하기 위해 집합 패킹 모형을 이용하여 구축된 MoDiSS(Model-based DSS in Ship Scheduling)를 사 용하였다. 이러한 연구결과들은 실제적인 해양 석유 생산 및 수송 최적화 문제에 의미 있게 적용될 수 있으리라 사료된다.
        3.
        2008.03 KCI 등재 서비스 종료(열람 제한)
        본 연구의 목적은 DEA를 사용하여 지방해양수산청의 생산효율성과 경쟁력을 측정하고자 하는 것이다. 선형문제 분석기 EMS를 사용하여 기술적 효율성 프론티어로 부터 한 방향 또는 다른 방향의 거리를 측정한다. 투입지향 측정은 산출 요소를 유지한 상태에서 효율성을 위한 투입요소의 감소치를 측정한다. 이와 같이 산출지향 측정은 입력 요소를 유지한 상태에서 효율성에 필요한 산출수치를 측정하고 무지향 측정은 효율성 개선을 위하여 투입과 산출에 대해 양방향으로 필요한 수치를 측정한다. DEA를 사용한 분석결과에 따라 비효율적 지방해양수산청은 항만행정과 공공기관의 생산 효율성을 강화하기 위하여 상대적으로 효율적인 지방해양수산청을 벤치마킹할 것이 권고된다. 생산효율성에 관한 자료는 모든 활용영역에서 정책 입안자에게 방법론을 제공하고 다양한 체제에서 운용할 수 있는 기초가 될 것이다.
        4.
        2004.08 KCI 등재 서비스 종료(열람 제한)
        컨테이너 적하계획은 항만 장비운용의 효율성을 결정짖는 주요 요인 중 하나이다. 적하계획 문제에 유전알고리즘을 응용할 때 처리 작업 수가 많게 되면, 기존의 방법으로 많은 시간이 걸린다. 이 문제를 해결하기 위하여 본 논문에서는 이주모델과 링구조 기반의 의사병렬 유전알고리즘을 개발하고 컨테이너의 최적 적하순서를 결정하는 문제에 적용하여 그 유효성을 밝힌다.
        5.
        2002.03 KCI 등재 서비스 종료(열람 제한)
        이 본문은 선박중개시스템으로써 분산객체기술을 이용한 CORBA환경하에서 설계되고 구현되었다. 최근 각광 받고 있는 웹에서의 전자상거래 시스템이 방대해 짐에 따라 호스트 중심의 중앙 집중식 방식이 한계를 가지게 되었다. 또한 시스템의 성능 향상도 크게 요구되어졌으며, 이러한 문제들을 해결하기 위해 이종 시스템간에 프로그램을 분산시켜 부하를 줄임으로써 시스템의 성능 저하와 네트워크 병목형상을 해결하고 있다. 본 연구는 에이전트 통신언어(ACL)를 이용하여 분산된 데이터베이스에fi의 에이전트 기반 모형을 제시한다. 또한 분산된 서로 다른 운영체제, 분산된 이종의 데이터베이스에서의 정보 공유와 교환이 가능한 CORBA를 이용한 지능형 선박검색 에이전트의 모형을 구현한다.
        6.
        2001.09 KCI 등재 서비스 종료(열람 제한)
        Optimum Ship Routing can be defined as 'The selection of an optimum track for a transoceanic crossing by the application of long-range predictions of wind, waves and currents to the knowledge of how the routed vessel reacts to these variables'. This paper treats the methodology how to solve optimum ship routing problem by network modeling and reveals the validity of the network model by some numerical experiments.
        7.
        2001.03 KCI 등재 서비스 종료(열람 제한)
        이 논문은 공공 컨테이너 터미널에서 직면하는 선석할당 계획문제를 다루고 있다. 선석할당 계획문제의 주된 논점은 ETA가 주어진 컨데이너 선박들을 어떻게 선석에 할당할 것인가를 결정하는 것이다. 선석할당 계획문제의 세 가지 최적화 모형들은 집합 문제 유형으로 정식화시켜 제시하였다. 또한, 제안된 최적화 모형의 의사결정 변수를 생성하기 위한 경험론적 알고리듬은 선박의 대기시간과 선석 점유율을 사용하여 고안하였다. 계산 실험은 실제 공공 컨데이너 터미널의 데이터로 수행하였으며, 그 결과들은 제안된 최적화 모형들과 경험론적 알고리듬들이 공공 컨테이너 터미널의 선석할당 계획문제에 대하여 유용하게 적용될 수 있음을 제시하고 있다.
        8.
        2000.12 KCI 등재 서비스 종료(열람 제한)
        This paper treats a genetic algorithm for ship scheduling problem in set packing formulation. We newly devised a partition based representation of solution and compose initial population using a domain knowledge of problem which results in saving calculation cost. We established replacement strategy which makes each individual not to degenerate during evolutionary process and applied adaptive mutate operator to improve feasibility of individual. If offspring is feasible then an improve operator is applied to increase objective value without loss of feasibility. A computational experiment was carried out with real data and showed a useful result for a large size real world problem.
        9.
        2000.06 KCI 등재 서비스 종료(열람 제한)
        The -advent of electronic navigation equipment and trustworthy computer which provides people with convenience made the management system by one-man bridge operation or the least people who are needed possible through the integration of communication network with various navigation equipment and related institution. One of the most needed ultra-modem navigation device for a mate, ECDIS is a core equipment for navigation in ENS that notifies peril to mate as well as supervises all tasks in hydrographical chart, voyage planning, course monitoring and voyage recording. We should make coast and ocean voyage planning first, for the secure navigation which is considering the course circumstances and next, for the reduction of voyage dates in economical aspect. There needs a thoughtful consideration about the feature of the ship itself and the course with weather condition in taking up the course and also we have to take into accounts about appropriate distance between ships. Considering the essential conditions of ECDIS the indispensable device in the future, it was developed the basic principle for voyage planning algorithm for officer and programmed to real implementation available. In this paper including most of the requirements in ECDIS performance standard I mentioned about such a basic and a core Principle with real application by using the Visual C++ programming language. The voyage plan includes the function that indicate and modifies all the way points in the course from department port to arrival port with erasing the wrong way points. Also, it provides in a document form that shows ETA at glance in average speed sailing.
        10.
        1999.12 KCI 등재 서비스 종료(열람 제한)
        This paper aims at developing an integrated fleet management support system for industrial carriers who usually control the vessels of their own or on a time charter to minimize the cost of shipping their cargoes. The work is mainly concerned with the operational management problem of the fleet owned by a major oil company, a typical industrial carrier. The optimal fleet management problem for the major oil company can be divided into two phase problem. The front end corresponds to the production operation problem of the transportation of crude oil, the refinery operation, and the distribution of product oil to comply with the demand of the market. The back end is to tackle the fleet scheduling problem to meet the seaborne transportation demand derived from the front end. Relevant optimization models for each phase are proposed and described briefly. Then a user-friendly integrated fleet management support system is built based on the proposed optimization models for both ends under Windows environment. A case study reflecting the practices of fleet management problem for the major oil company is carried out by using the system.
        11.
        1998.12 KCI 등재 서비스 종료(열람 제한)
        There are three basic modes of operation of ships: liner, tramp and industrial operations. Industrial operations, where the owner of the cargo, i.e. the industrial carrier controls the ships, abound in the shipment of bulk commodities, such as oil, chemicals and ores. Industrial carriers strive to minimize the shipping cost of their cargoes. This paper is concerned with the operational optimization problem of a fleet owned by major international oil company. The major oil company is a holding corporation for a group of oil producing, transporting, refining, and marketing companies located in various countries throughout the world. The operational optimization problem of the fleet is divided into two-phases. The front end corresponds to the optimization of transporting crude oil, product mix, and the distribution of product oil to meet market demand. The back end tackles the operational optimization problem of the fleet to meet the transportation demand derived from the front end. A case study is carried out with the H major oil company problem composed by reflecting the practices of an international major oil company. The results are summarized and examined in the point of optimization for the total operation of the H major oil company and the operational optimization problem of the fleet. The paper concludes with the remark that the results of the study might be useful and applicable in practices of these related decision problems.
        12.
        1996.02 KCI 등재 서비스 종료(열람 제한)
        Vessles in the world merchant fleet generally operate in either liner or bulk trade. The supply and the demand trend of general cargo ship are both on the ebb, however, those trend of tankers and containers are in slight ascension. Oil tankers are so far the largest single vessel type in the world fleet and the tanker market is often cited as a textbook example of perfect competition. Some shipping statistics in recent years show that there has been a radical fluctuation in spot charter rate under easy charterer's market. This implys that the proper scheduling of tankers under spot market fluctuation has the great potential of improving the owner's profit and economic performance of shipping. This paper aims at developing the TS-DSS(Decision Support System for Tanker Scheduling) in the context of the importance of scheduling decisions. The TS-DSS is defined as the DSS based on the optimization models for tanker scheduling. The system has been developed through the life cycle of systems analysis, design, and implementation to be user-friendly system. The performance of the system has been tested and examined by using the data edited under several tanker scheduling scenarios and thereby the effectiveness of TS-DSS is validated satifactorily. The authors conclude the paper with the comments on the need of appropriate support environment such as data-based DSS and network system for succesful implementation of the TS-DSS.
        13.
        1994.05 KCI 등재 서비스 종료(열람 제한)
        This paper treats the optimization analysis of tactical ship scheduling problems in the world seaborne bulk trade. The authors use the term 'tactial' to describe the ship scheduling problem where the owners should employ skillful tactics as an expedient toward gaining the higher profits per period in short term. Relevent research and related problems on ship scheduling problems are reviewed briefly and a model for the tactical ship scheduling problem formulated as Set Problem is introduced by modifying the previous work of Fisher(1989). The reality and practicability of the model is validated by some ship-ping statistics. Proper solution approaches are outlined in the context of computational tractability in tackling the Mixed Integer Propramming. Some underlying consideration for the computational experiment is also mentioned. The authors conclude the paper with the remarks on the need of user-friendly Decision Support System for ship scheduling under varying decision environment.
        14.
        1991.06 KCI 등재 서비스 종료(열람 제한)
        This paper intends to develop a Prototype Expert Collision Avoidance System by introducing expert system techniques into the decision block of anti-collision loop. The problem domain of this study is characterized and specified by combining the concepts of anti-collision loop and knowledge -based system for collision avoidance. Domain in knowledge which may originates from the appropriate sources such as the International Regulations for Preventing Collision at Sea 1972, Marine Traffic Laws, and many texts on the subject of anticollision navigation and good seamanship is acquired and formalized into the knowledge-base system using production rule. Finally, a Prototype Expert Collision Avoidance System is built by using the CLIPS, developed by AIS NASA written in and fully integrated with the C language, and some test-and-run results of the system are demonstrated and examined. The author considers the proposed system which is named PECAS to be meaningful as a test bed for a further refined Expert Collision Avoidance System on board the Automated Ship.
        15.
        1988.04 KCI 등재 서비스 종료(열람 제한)
        Decision Science or Decision Analysis can be described as a scientific methodolog to provide suitable quantitative information for the decision maker to be able to selected the best feasible alternative on the given decision environment and thus we can say that where there are decision problems, there needs the decision analysis to be applied to them. International shipping is generally said to be the cheapest and most widely used means of transport in international trade and each of the hundreds of seaport. So far as the decision makings in the shipping and port transportation are concerned, of real importance is to understand what the decision problems in each of shipping and port transportation really are and to recognize the meaning of relevance between shipping and seaport in the outworn phrase, that is to say, "The chain is as strong as its weakest link." This paper is intended to present a literature survey on the applied decision analysis to shipping and port transportation problems which have actually been involved in the wide variety of decision environment. At first, the author suggests four divisional framework such as decision analysis in each field of Shipping Economics, Management and Operations of Shipping, Port Economics, and Port Operation and Management, according to the main concern of the decision environment, and then the literature surveys on those four major divisions are described including the problems and solution approaches in each case. The author concludes the paper with the comment on the need of joint research around this area by citing the phrase of "a process of updating the decision makers' intuitions."s' intuitions."quot;
        16.
        1986.06 KCI 등재 서비스 종료(열람 제한)
        Abroad-band design method of a lumped-element 3 dB quadrature hybrid without magnetic coupling is proposed and discussed, where techniques of cascading fundamental hybrids via second-order delay equializers and adding matching sections are adopted. It is shown that the designed broad-band lumped-element 3 dB quadrature hybrid can be easily constructed and its bandwidth reaches up to 54%. Furthermore, the experiments have been carried out, the results of which agree with the theoretical ones, and hence, the validity of the broad-band design method proposed here was confirmed.
        17.
        1985.10 KCI 등재 서비스 종료(열람 제한)
        The purpsoe of automatic steering system is to keep the ship's course stable with the minimum course error and rudder angle, and there have been a number of studies as to the optimal design and adjustment of the autopilot. Recently, modern control theories are being used widely in analyzing and designing the system. When a ship is at sea, autopilot installed on the ship plays an important role, particularly in the respect of economic aspects, that is, when the design and the adjustment of adjustable parameters are not conducted perfectly, the amount of loss in energy and the extension of sailing distance become large. Therefore the optimal design and adjustment of a autopilot are very important. Though P.I.D type autopilots are widely spread and generally used in modern ships, the suitability and the adjusting method are not clarified. In this paper the authors considered the stabilaity and the economical efficiency of the P.I.D. type autopilot and investigated various facts which should be considered at the time of designing and using the P.I.D. type autopilot through the digital computer simulation.
        18.
        1985.06 KCI 등재 서비스 종료(열람 제한)
        It has been generally known that the chattering of an AC electromagnetic contactor due to the fluctuation of attracting force is the primary cause of its abrasion and noise. To reduce this chattering effect, an AC electromagnetic contactor is mostly fitted with a shading coil which works the role to make difference in phases of two distinct components of attracting force. The theoretical interpretation of an AC electromagnetic contactor with shading coil and the equation of its attracting force per unit wattage consumed have already been proposed, however, few explications so far have been made on the determination of optimal circuit constants of shading coil. In this paper, the auther constructs a circuit model of an AC electromagnetic contactor with shading coil which is based on the theoretical interpretation of shading coil examined to be valid by experiments under some assumptions, and defines the equation of attracting force without chattering per unit wattage consumed as a performance function for determining the optimal circuit constants of shading coil. And then, the optimal circuit constants maximizing the performance function are determined by means of computer simulation founded on the above circuit model and the characteristics of those circuit constants are examined with special attention to the coupling coefficient.
        19.
        1982.12 KCI 등재 서비스 종료(열람 제한)
        The attempt of this paper is to examine the basic theory on the analysis of the effect of a shading coil fitted to an electromagnetic contactor, and to compare experimentally the attracting force of an AC electromagnetic contactor with that of a DC electromagnetic contactor, with varying the airgap length. Equations are also proposed for calculating the AC and DC attracting force per unit consumption wattage by using the circuit constants measured from the experiment, and these calculated attracting forces are compared with those actulally measured, and then, the experimental contactor is examined in the view of its design. The calculated attracting forces are appeared to coincide well with the measured ones and the experimental contactor fitted with shading coil is revealed not so well designed for reducing the fluctuation of the attracting force.