• 한국주조공학회지
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• 제28권3호
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• pp.129-135
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• 2008

The reheating stage of electromagnetically stirred Al billet is a critical factor in the thixoforming process. When reheated to the solid-liquid state, the microstructure evolves to a more globular and more homogeneous structure by a coarsening mechanism, the kinetics depending on the initial microstructure. Microstructural evolution has been characterized by conventional parameters (mean size of particle and shape factor) as a function of holding time in the solid-liquid state. The aim of this study is to report experimental results concerning microstructural evolution in the solid-liquid state of electromagnetically stirred Al billet. The material was elaborated in the form of continuously cast bars solidified with electromagnetic stirring to degenerate the dendritic structure. The choice of the reheating conditions is determined by a dendritic ripening and coalescence mechanism, involving variations of both the shape and size of the particles. The reheating time has to be long enough to allow a minimum degree of spheroidizing, but has to be limited as much as possible in order to avoid excessive ripening. The optimum microstructure was obtained at the reheating temperature of near $584^{\circ}C$ and the holding time of 5 min. The only means of combining high productivity with good casting quality was to use feedstock billets whose microstructure showed rapid transformation characteristics.

• 한국실내디자인학회논문집
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• 제25권3호
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• pp.129-137
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• 2016

Dark and desolate underground parking spaces in commercial facilities are optimal spaces for crime. First, this study reviewed 15 precedent CPTED guidelines and related literatures, and as a result extracted 45 CPTED planning criteria for underground parking facilities. Secondly by field survey, we investigated six parking spaces in commercial facilities whether they were planned properly based on 45 checklist items, in six categories of CPTED principles. In result, target facilities showed average 46.8% relevance ratio, which means less than a half of 45 items of CPTED planning factors were not applied. Guidelines suggest desirable illuminance level of more than 100 lux, however the measurement of illuminance levels in some parking spaces showed below 50 lux. Relatively department stores were keeping CPTED guidelines better than large discount mart and mixed used facilities. Definition of territory of loading dock and customer area should be clarified, clear signage and color scheme in different zones should be represented with higher level of territorial responsibilities and surveillance in mixed used facilities for further improvement.

• 산업공학
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• 제13권2호
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• pp.225-233
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• 2000

In this paper, we develope a genetic algorithm for the erection scheduling in shipbuilding. Erection, the final manufacturing stage of shipbuilding, involves the landing and joining of blocks at drydock. Since several ships are built simultaneously at the same drydock and they compete with the common constrained production resource such as labor, space, and crane, we should consider both ship-specifics and common resource constraints for the desirable erection scheduling. Ship erection should also satisfy the predetermined dock cycle given from higher level production planning. Thus, erection schedule of a ship can be represented as a PERT/CPM project network with its own deadline. Since production resources are shared, the erection scheduling become the so-called multi-project scheduling problem with limited resources, which can not be solved easily due to the large size of project network. We propose a function as a minimization of load index which represented the load deviation over time horizon considering the yard production strategy. For the optical parameter setting, we tried various experiments. We verified that the proposed approach was effective to deal with the erection scheduling problem in shipbuilding.

• 대한산업공학회지
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• 제37권3호
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• pp.248-257
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• 2011

Cross docking is a logistics management concept in which items delivered to a terminal by inbound trucks are immediately sorted out, routed and loaded into outbound trucks for delivery to customers. Two main advantages by introducing a cross docking terminal are to consolidate multiple smaller shipment into full truck load and remove storage and order picking processes to save up logistics costs related to warehousing and transportation costs. This research considers the scheduling problem of trucks in the cross docking terminals with multi-door in an inbound and outbound dock, respectively. The trucks sequentially deal with the storage process at the one of inbound doors and the shipping process at the one of the outbound doors. A mathematical model for an optimal solution is derived, and genetic algorithms with two different chromosome representations are proposed. To verify performance of the GA algorithms, we compare the solutions of GAs with the optimal solutions and the best solution using randomly generated several examples.

• 대한조선학회논문집
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• 제31권3호
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• pp.119-128
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• 1994

기관실 상갑판 특히 거주구 외부의 상갑판 판부재는 외적인 수직하중이 거의 작용하지 않음에도 불구하고 건조중인 대형선박에서 갑판에 널리 대처짐 현상이 발생할 때가 있는 반면에 수직하중이 작용하는 거주구 내부의 기관실 상갑판은 처짐발생 크기 및 분포정도가 미미한, 규명하기 어려운 현상들이 나타나고 있다. 따라서, 본 연구에서는 3차원 구조해석으로부터 얻은 거주구 및 자중에 의한 정적하중의 영향, 손상보고에 따라 계측된 처짐량 자료 및 분포상황, 초기처짐의 크기 및 형상, 용접잔류응력, 면내하중 성분들을 대상으로 비선형 시리즈 해석을 수행하고, 이로부터 판부재에 발생하는 최대처짐 추정식을 제시하였다. 또한, 본 연구를 통하여 개발된 추정식을 이용하여 기존 손상선박의 처짐원인 분석, 거주구 탑재 및 진수 전후의 기관실 상갑판의 처짐거동 그리고 기존의 선각품질관리기준이 기관실 상갑판의 처짐에 미치는 영향을 살펴보았고, 마지막으로 건조예정에 있는 기관실의 처짐현상을 예측하여 보았다.

• 한국기후변화학회지
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• 제6권4호
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• pp.345-355
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• 2015

In this study, we researched a space allocation method of emissions from domestic coastal shipping (passenger ship, cargo ship, fishing boats). We were building a geographic information data that is used in GIS for emissions of space allocation, and presented a methodology capable of performing the space allocated for each grid by calculating the emissions. Passenger ships were assigned emissions of routes each the ship that operated at a fixed. Emissions of crusing mode of cargo ship, was equally assigned to the safe operation line, which is defined for domestic cargo ship. Also, Emissions of maneuvering (moving into or out of port) and hoteling (operations while stationary at dock), was assigned in consideration of anchorage in the major port. Fishing boat was evenly allocated monthly emissions in the country every month fishing grounds formation zone. Based on these results, it tries to provide the basic data that can be used when you want to create a local government measures to reduce scenario in the future.

• 한국항만학회지
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• 제4권1호
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• pp.45-57
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• 1990

Today, about 95% of totoal import import and export container cargo in Korea is being transported through the Busan Port. The 59% of these cargos is being handled at BCTOC and the rest is at the existing piers. As the Off-Dock Container Yards(ODCY) within Busna City are located at 33 different places, it causes serious problems in the container cargo transport and inland traffic near Busan district. The container carriers to the inland market or other terminals cause heavy traffics to the Busan Traffic System. Hence, this impacts to the cost of the cargo handling equipment and cargo storage, the usage of labor resources, the control of natural environment etc. To solve those problems, it is required to build Inland Container Depot(ICD) in the Southeastern Economic Area. In this study therefore, we try to calculate the required area of Inland Container Depot(ICD) for Busan Port which deals which deals with the container cargo. We also investigate the sites for ICD being suggested outside of Busan City. We use the Analytic Hierarchy Process(AHP) Method to decide the best one. The result shows that the best is the Site B(Dong Myen, Yangsan Kun).

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1305-1314
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• 2023

The global ship repair and modification market is expected to grow up to approximately $ 30 billion by 2025. Korea's shipbuilding industry is leading the world grounded on its international competitiveness in design and production technology. The reality, however, is that the ship repair and modification industry is centered on Gyeongnam, and there are only two to three ship repair workplaces that can repair large ships. Therefore, domestic ship repair companies target small and medium-sized ships mainly. This is because there are few workplaces equipped with a large dock in which large ships like LNG ships can be inspected regularly or repaired, complaints are severe for environmental problems, and related environmental regulations are so strict that it is very hard to obtain government approval for the extension of ship repair and modification workplaces or the opening of new shipbuilding sites. Besides, on account of the workers' high wages, few experts related, and higher ship repair price compared to that of Southeast Asia, most of the volume of repairing large ships including domestic LNG ships is being lost to Southeast Asian or Chinese markets. In this study, the work process and pre-work preparation process for ship hull (winch, windlass, hatch cover, ramp door, cargo gear, anchor chain) repair were analyzed and presented to foster domestic ship repair experts and revitalize related industries.

• 한국항해항만학회지
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• 제48권2호
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• pp.116-124
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• 2024

Automatic docking of small planing ship is a critical aspect of maritime operations, requiring accurate prediction of motion states to ensure safe and efficient maneuvers. This study investigates the use of Artificial Neural Network (ANN) to predict motion state of a small planing ship to enhance navigation automation in port environments. To achieve this, simulation tests were conducted to control a small planing ship while docking at various heading angles in calm water and in waves. Comprehensive analysis of the ANN-based predictive model was conducted by training and validation using data from various docking situations to improve its ability to accurately capture motion characteristics of a small planing ship. The trained ANN model was used to predict the motion state of the small planning ship based on any initial motion state. Results showed that the small planing ship could dock smoothly in both calm water and waves conditions, confirming the accuracy and reliability of the proposed method for prediction. Moreover, the ANN-based prediction model can adjust the dynamic model of the small planing ship to adapt in real-time and enhance the robustness of an automatic positioning system. This study contributes to the ongoing development of automated navigation systems and facilitates safer and more efficient maritime transport operations.

• 한국항해항만학회지
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• 제30권10호
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• pp.819-823
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• 2006

부산항 북항은 일제 강점기에 축조된 일반부두(1,2,중앙,3,4)에서 시작하여 자성대, 신선대, 감만 부두 등으로 확장되었다. 그러나 도심과 접한 항만의 입지적 특성으로 인하여 물류 활동 및 도시 활동 양 측면에서 문제가 대두되어 왔다. 장치장 부족으로 인한 부두밖 장치장(ODCY) 확대가 대표적이다. 이것은 물류비용 증가뿐만 아니라 우암로, 충장로 등 주요 간선도로상의 화물 차량 비중을 높이는 결과를 가져와서 심각한 사회 문제가 되고 있다. 본 연구는 일반부두와 자성대부두 재개발로 인한 충장로, 우암로 등 인접 주요 간선도로의 통행량 감소 효과를 분석하고 그동안 차량 통행으로 발생된 교통혼잡으로 인한 사회적 비용의 절감효과를 분석하여 두 부두의 재개발로 인한 효과를 제시하는 데 목적이 있다.