• 유통과학연구
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• 제15권11호
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• pp.59-72
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• 2017

Purpose - This paper evaluated the efficiency performance of the three major maritime transport markets and examined the determinants of the performance. The firms' revenue fluctuates with the changes of the economic cycle; hence it is important for them to set up business strategies to improve efficiencies. A lack of efficiency measurements for shipping firms leads to a significant gap in determining their overall performance. Research design, data, and methodology - Each of DEA scores was adopted for the evaluation and panel regression was used to examine the impact of determinants on the performance. The analysis included 50 shipping firms from three maritime transport markets as follows; 15 firms of container liners, 18 firms of bulk carrier and 17 firms of tanker carriers, and its period was from 2010 to 2016. Results - In the CCR model, container liners were the highest, tanker carriers were the second, and bulk carriers were the lowest in operation efficiency and financial efficiency. By region, operation efficiency and financial efficiency was high in the order of America, Asia, and Europe. Conclusions - This study suggests business strategies for maritime transport companies based on the analytical results of determinants of operational and financial efficiency.

• 설비공학논문집
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• 제12권11호
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• pp.982-993
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• 2000

This paper describes an optimal control scheduling of an encapsulated ice storage system with a chiller of nominal chiller 34RT(103,200kcal/hr) and an ice storage tank of 170RT-hrs(514,080 kcal). The optimization technique used in the study is dynamic programing. The objective function is summed cost during a day including charge and discharge periods. Control strategies being used commercially are chiller priority and storage priority control. In chiller priority control, the chiller is allowed to run at full capacity during the day, subject to limitations of the building load, and the ice is only melted when and if the load exceeds the chillers full capacity. In contrast to chiller priority control, the aim in storage priority control is to melt as much as ice as possible during the day time period. The system simulation calculates the operation costs for the three control strategies in the condition of the same cooling load and the same ice storage system. The simulation period is a day, assuming that initially the tank is stored fully and the cooling load is perfectly predicted for the scheduling. Also Final state of the tank is to be charged fully.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.904-911
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• 2016

This paper presents a novel driving system by the humanoid robot to drive a vehicle in disaster response situations. To enhance robot's capability for substituting human activities in responding to natural and man-made disaster, the one of prerequisite skills for the rescue robot is the mounted mobility to maneuver a vehicle safely in disaster site. Therefore, our driving system for the humanoid is developed in order to steer a vehicle through unknown obstacles even under poor communication conditions such as time-delay and black-out. Especially, the proposed system includes a tele-manipulation interface and stable navigation strategies. First, we propose a new type of path estimation method to overcome limited communication. Second, we establish navigation strategies when the operator cannot recognize obstacles based on Dynamic Window Approach. The effectiveness of the proposed developments is verified through simulation and experiments, which demonstrate suitable system for driving a vehicle in disaster response.

• 한국항만경제학회지
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• 제21권3호
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• pp.171-189
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• 2005

In order to improve inefficient and unproductive factors and in response to criticisms of the failure in harbor privatization introduced in 1997, the Korean government introduced the Port Authority system, which is commonly adopted in advanced harbors in the world. This research examined the theoretical background of harbor management system and various cases of harbor management in foreign countries. The desirable introduction of Port Authority system must be preceded by the settlement of problems in harbor structure and operation. In addition, the Port Authority Act, which restricts the autonomy of harbor corporations, should be improved for user-centered Port Authority system. Strategies for the successful introduction of Incheon Port Authority are as follows. Firstly it is required to establish consumer-centered harbor operation system. The second requirement is to activate the harbor logistics industry through the development of nearby logistic complexes led by Port Authority and, by doing so, to promote the development of local economy. Thirdly it is essential to lay the foundation of mutual prosperity through developing profitable businesses by linking localities and harbors, and to suggest a crisis control network for Port Authority and local self-governing bodies to cope jointly with crises in logistics and natural disasters.

• 산업경영시스템학회지
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• 제45권3호
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• pp.115-122
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• 2022

As cable TV, which has been leading the paid broadcasting market, has given the lead to IPTV, which has huge communication capital, its competitiveness is gradually weakening. This study examines the operation status of local cable TV and seeks ways to strengthen competitiveness for survival. To this end, we conducted data analysis such as related statistics, broadcasting industry survey reports, IPTV growth reports, CMB management indicators, paid broadcasting literature data, marketing reports, industry success stories, and marketing mix and SWOT analysis. As a result, four strategies for strengthening the survival competitiveness of local cable TV, namely joint purchase apartment marketing strategy, influencer marketing strategy, relationship marketing strategy, and digital marketing strategy were derived. Therefore, the results of this study can contribute to the improvement of the competitiveness of local cable TV, which has been with local residents through close content, and can be used as basic data for establishing marketing strategies for local cable TV in the future.

• 디지털융복합연구
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• 제20권5호
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• pp.499-512
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• 2022

본 연구는 포스트 코로나 시대에 대비해 안양시 공공도서관이 온라인 미디어를 효과적으로 활용할 수 있는 방안을 제안하고자 하는 목적에서 수행되었다. 이를 위해 2021년 전국 도서관 운영 평가에서 정부 포상을 받은 우수 도서관 5곳의 운영 사례를 분석해 주요 시사점들을 정리하고, 분석 내용들을 바탕으로 안양시 도서관이 온라인 미디어를 활용해 도서관 운영을 활성화 하는 데 도움이 될 수 있는 방안들을 도출하였다. 본 연구는 코로나19 시기 성과들을 바탕으로 우수 도서관으로 선정된 도서관들의 실제 사례를 토대로, 포스트 코로나 시대에 대비해 안양시 도서관의 온라인 미디어 활용 전략을 정리해 제안한 실증적이고 경험적인 연구라는 점에서 의의를 찾을 수 있다.

• 지능정보연구
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• 제12권1호
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• pp.125-137
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• 2006

컨테이너 터미널에서의 효율적인 운영을 위한 장치장 운용계획은 터미널 생산성을 향상 짓는 중요한 요소이다. 본 연구에서는 장치장 운용 시 고려되는 의사결정 요소들을 살펴보고 그 대안을 제시하였다. 의사결정 요소는 크게 두 가지로 장치 장에 컨테이너 저장 시 고려되는 블록의 용도구분에 관한 것과 각 블록에 할당하는 RMGC(Rail Mounted Gantry Crane) 야드 크레인의 대수를 결정하는 것이다. 각 요소 별 제시되는 대안은 시뮬레이션기법을 통하여 평가해 보고자 한다.

• 한국유체기계학회 논문집
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• 제7권3호
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• pp.39-47
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• 2004

Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions lot a considerable amount of their lifetime. This study analyzes off-design performance characteristics of micro gas turbines and addresses the importance of the recuperation process doting the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration, and current vs advanced engines. Major finding is that maintaining high turbine exhaust temperature is crucial for efficient operation of micro gas turbines.

• 한국농공학회지
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• 제39권2호
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• pp.1-8
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• 1997

Abstract The need for integrated reservoir system operation become more intense as the demands from the system increase. A deterministic, three-dimensional discrete incremental dynamic programming approach is presented to derive reservoirs system operational planning strategies. The developed H3DP model optimizes the monthly operation of the Hwachon and Soyang Projects on the North Han river and Chungju Main Project on the South Han river. By using the H3DP model, Hwachon project was reevaluated as a component of the upstream multipurpose storage reservoirs in the basin based on 1993 hydrology. This case study demonstrates the practical use of the developed model for the basin multi-reservoir system operation in an integrated, multipurpose fashion.

• 대한기계학회논문집B
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• 제30권8호
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• pp.756-763
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• 2006

PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.