• 전력전자학회논문지
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• 제25권4호
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• pp.286-292
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• 2020

This study proposes a power decoupled multi-port dual-active-bridge (DAB) DC-DC converter employing multiple transformers. Conventional multiport DAB DC-DC converters experience a power coupling issue from the use of a single transformer, which essentially requires complex power decoupling control. To solve this issue, a multiport DAB DC-DC converter employing multiple transformers is proposed to decouple output power without additional complex control algorithms. The proposed converter uses multiple transformers that can expand output ports easily. Therefore, transformers and the proposed multi-port DAB converter can be designed simply. In addition, the number of coupling inductors can be reduced in the proposed three-port DAB converter compared with that in conventional multiport DAB converters. The power decoupling characteristics and equivalent circuit of the proposed converter are analyzed using theoretical model approaches. Finally, a 3-kW laboratory prototype is developed to verify the effectiveness of the proposed converter.

• 대한기계학회논문집B
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• 제23권1호
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• pp.92-103
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• 1999

The fuel spray behavior in the intake port of an electronic control port irijection gasoline engine has a strong influence on engine performance, exhaust emission and fuel consumption. Thus, in this study, fuel spray behavior and flow characteristics of the air assist gasoline spray injected into a suction flow in a simulated rectangular intake port have boon investigated. Macro-behavior of spray characteristics was investigated by means of visualization and the measurements of SMD and velocity were made by PDPA. For analysis the flow field with droplets size, droplets are classified five droplets size groups. As a result, the normal distance of suction flow increasing, the relatively large droplets distribution and SMD increase because small droplets easily follow suction flow. Near impinging wail, after impinging against the wall, secondary atomized small droplets of D < $30{\mu}m$ bound from the wall. And the increasement of suction flow progress to the large droplets of D > $100{\mu}m$ distribution. Therefore, SMD are apparently increased near impinging wall, Z/d = 9.0.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.49-49
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• 2018

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1996년도 정기학술강연회 발표논문 초록집
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• pp.42-44
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• 1996

Recently due to repeatedly occurrence of flood, a lot of Chinese cities accept new design criteria for their protective project Most of them calculated by a certain type of probability distribution. In order to meet the demand of development economy the return period of design criteria is changed more longer and longer even 1000years, but the data which the calculation dependent on is only about 30-40 years. (omitted)

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1998년도 추계학술대회 및 정기총회
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• pp.21-24
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• 1998

Simulation modeling has become an extremely important approach to analyzing complex system. In recent years the number of people using simulation as problem-solving aid has increased. In this Paper, we developed a simulation model for analyzing the physical distribution system in ports. We used Arena 2.2 which is a kind of simulation software based common simulation language, SIMAN V. And then, we applied this model to kwangyang port(partially) and analyzed the effect of it upon port system in according to change of the quantity of goods transported.

• 한국항해학회지
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• 제7권1호
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• pp.1-32
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• 1983

The delay due to congestion has recently attracted widespread attention with the analysis of over-all operation at the port. But, the complexity of the situation is evident in view of the large number of factors which impinge on the considerable end. Queueing theory is applicable to a large scale transportation system which is associated with arrivals of vessels in a large port. The attempt of this paper is to make an extensive analysis of the port transport system and its economic implications from the viewpoint that port is one of the physical distribution facilities and a kind of queueing system which includes ships and cargoes as port customer. By analyzing the real data on the Port of Pusan, it is known that this port can be represented as a set of multi-channel with identical setof Poisson arrival and Erlang service time, and also it is confirmed that the following formula is suitable to calculate the mean delay in this port, namely, $W_4={\frac{\rho}{\lambda(1-\rho)} {\frac{e_N(\rho{\cdot}N)}{D_{N-1}(\rho{\cdot}N)}$ where, ${\lambda}$: mean arrival rate $\mu$: mean servicing rate; N: number of servicing channel; ${\rho}$: utillization rate (${\lambda}/N{\mu}$) $e_N$: the Poisson function Coming to grips with the essentials of the cost of delay due to congestion, a simple ship journey cost model is adopted and the operating profit sensitivity to variation in port time is examined, and for purpose of a future development for port princing service the marginal cost is approximately calculated on the basis of queueing theory.

• 한국항만경제학회지
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• 제17권1호
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• pp.53-72
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• 2001

This study focuses on analyzing the economic effects and probes the necessity of establishing a customs free zone at the Port of Busan. It first considers the economic effects of establishing a customs free zone at the Port of Busan, then suggests policy prescriptions for introducing and operating the free zone system and improving the logistics functions of the Port. The timeline of this study is focused on 2007, when all of Busan Port will operate as a customs free zone and the first stage of the New Busan Port and distribution parks will be built and opened for operation. The regression analysis, which was conducted using the inter-industry relations table(input-output table data), provided a quantitative prediction on the effects of making Busan Port into a customs free zone. Regarding the impact of a free zone system on the domestic and regional economy, this research found that the impact of a customs free zone on domestic industries and the regional economy once the customs free zone is established throughout all of Busan Port would be highly positive. The positive economic effects on the domestic and Busan regional economy might be further strengthened if the value-added logistics function of Busan Port could be supplemented by effective linking to the hinterlands.

• 한국항해항만학회지
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• 제29권7호
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• pp.635-640
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• 2005

This paper aims to understand and analyze the mega-trends such as trends towards larger vessels due to an increasing trade volume, accordingly fewer port calls, strategic alliances and M&A Increasing degree of concentration through M&A activities in shipping industry results in a decreasing number of shipping finns with an increasing share in the world shipping capacity. But competition is strongly increasing on main trunk routes. Therefore, shipping concentration directly leads to further concentration of port traffic in fewer and larger ports with an increasing competition among neighboring ports.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1998년도 추계학술대회논문집:21세기에 대비한 지능형 통합항만관리
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• pp.323-329
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• 1998

In Pusan port, the studies, which analysis container cargo volumes by using forecasting methods and research about container logistics system, etc., have been continuously performed. But, in Pusan port, this study on an evaluation of traffic congestion has been scarcely performed until now. Especially, when changing and extending a berth, and constructing a new port, it is very important to examine this field. And it should be considered. Thus, this paper aims to analysis the effect of ship traffic condition in 2011, to evaluate marine traffic congestion, according to changing ship traffic volumes in Pusan port. To analysis it, we used simulation method and examined the results

• 한국터널지하공간학회 논문집
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• 제19권3호
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• pp.517-532
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• 2017

도심지 터널에 주로 적용되는 횡류식 환기방식은 환기구간 거리가 길어질수록 환기성능이 저하되므로 균일한 풍량분배가 필요하다. 본 연구에서는 환기구간 거리가 길어져도 균일한 풍량분배를 통해 설계값의 환기성능을 확보할 수 있도록 급배기구의 개도율을 최적화하는 프로그램을 개발하였으며, TUNVEN DUCT 프로그램과의 비교를 통해 프로그램의 예측 성능을 검증하였다. 이를 위해 반횡류 급기 환기방식을 적용하였으며, 두 프로그램은 유사한 포트 크기 및 풍량 분배를 예측하고 있으며, 계산값의 변동범위는 각각 11.71% 와 1.36% 인 것으로 나타났다. 이 프로그램은 다양한 터널 연장 및 급배기 포트 설치 조건에 대한 신속한 분석이 가능하므로, 횡류식 및 반횡류 환기방식의 포트 최적화 설계에 상당히 유용할 것으로 판단된다.