• 한국산학기술학회논문지
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• 제14권7호
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• pp.3184-3190
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• 2013

근래에 조선 해양 구조물 분야의 대부분 설계와 공정 계획은 각 회사가 보유한 전용 CAD/CAM 시스템을 통해 수행되고 있다. 이는 설계 형상 및 생산 관련 정보들이 추출되어 시간과 인력이 소비되는 많은 분야에서 해당 정보를 유용하게 사용할 수 있는 프레임워크가 구축되는 초석이 마련되었음을 뜻하며, 가장 전형적인 예로 선박 및 해양 구조물의 생산에 있어서 용접 관련 정보 산출 문제가 있는데 초기 일정 계획에 있어서 사용될 용접물량의 정확한 예측은 구조물 중량 그리고 도장면적 산출과 더불어 생산 과정의 자연스런 흐름을 가능케 하며 예상 소요 인력과 비용을 확보할 수 있는 극히 중요한 과정으로 인식되고 있다. 본 연구에서는 ERP 시스템에서 추출된 구조물의 형상 및 생산정보로부터 정확한 용접장 및 용접물량을 추정할 수 있는 프레임워크를 구축하고 프로그램을 개발하였다. 산출된 용접 정보는 용접 자세, 조립단계, 블록, 베벨 그리고 용접타입에 따라 분류되며, 적절한 Factor를 통해 용접작업에 필요한 시수와 비용을 예측하는데 사용된다.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.18-23
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• 2017

조선소의 안벽공정은 복잡한 구조물의 내부에 많은 인원이 투입되어 다양한 작업이 동시 다발적으로 이루어 지고 있다. 이에 따라 폭발, 화재 등 중대재해 발생의 가능성이 높으나, 사고 발생 시 내부 인원에게는 사고 발생의 여부와 대피에 대한 정보가 효과적으로 전달되기 어려운 실정이다. 최근 조선소 안전사고의 증가에 따라 안전과 공정 모니터링에 대한 요구사항이 강화되고 있다. 이에 주요 조선소에서는 IT 기술을 접목하여 공정을 실시간으로 모니터링하고 작업자의 안전을 위해 작업 환경을 감지하기 위한 연구가 진행되고 있다. 본 연구에서는 밀집된 구역에 다수의 인원이 존재하는 상황에서 비상상황이 발생하는 경우 대형 인명사고를 줄이기 위하여 모바일을 기반으로 화재 발생 등 위험 구역 정보와 사용자가 입력한 위치를 기반으로 안전하고 정확한 대피경로를 생성하여 제공하는 방법에 대한 연구를 수행하였다. 이를 위하여 지상의 건물에 대하여 진행되고 있는 화재 대피 시스템의 동향을 분석하고 탈출 경로 계산을 위한 다양한 알고리즘을 비교하여 본 연구에 적합한 알고리즘을 선정하고 프로그래밍을 수행하였으며 비콘을 이용한 위치 파악 기술의 적용 가능성을 확인하기 위한 기초 실험을 수행하였다. 제안된 방법은 초대형 선박 건조 현장, 여객선 및 대형 공공시설 등에 활용되어 안전사고 시 인명사고를 감소시킬 수 있을 것으로 기대된다.

• 대한기계학회논문집A
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• 제34권10호
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• pp.1507-1512
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• 2010

본 연구에서는 조선용 6mm 아연코팅강판의 $CO_2$ 레이저 겹치기 용접시 발생하는 유기 플라즈마를 마이크로폰과 포토다이오드로 측정하였다. 이때 겹치기 갭간극에 따른 용접조건을 RMS한 신호와 비교 분석하였다. 이를 통해 아연증발량이 증가함에 따라 RMS값도 증가하였으며, 겹침부의 조건에 따라 결함 발생시 RMS의 급격한 변화도 확인할 수 있었다. 또한 용접조건에 따른 Raw signal의 FFT값을 구한 후, 이때 구해진 주파수값을 밴드폭으로 설정하여 Raw signal을 필터링한 뒤의 RMS값을 용접비드와 대응하여 필터링하지 않은 RMS와의 차이점도 비교 분석하였다. 이를 통해 기존의 방법들보다 신뢰성 높은 In-process 모니터링이 가능함을 확인하였다.

• 대한조선학회논문집
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• 제53권2호
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• pp.115-126
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• 2016

In the process of ship building, it is known that the maintenance of working period and saving cost are one of the important part during the logistics of blocks transportation. Precise operational planning inside the shipyard plays a big role for a smooth transportation of blocks. But many problems arise in the process of block transportation such as the inevitable road damage during the transportation of the blocks, unpredictable stockyard utilization of the road associated with a particular lot number, addition of unplanned blocks. Therefore, operational plan needs to be re-established frequently in real time for an efficient block management. In order to find the shortest path between lot numbers, there are several representative methods such as Floyd algorithm that has the characteristics of many-to-many mapping, Dijkstra algorithm that has the characteristic of one-to-many mapping, and the A* algorithm which has the one-to-one mapping, but many authors have published without the mutual comparisons of these algorithms. In this study, some appropriate comparison have been reviewed about the advantages and disadvantages of these algorithms in terms of precision and cost analysis of calculating the paths and planning system to operate the transporters. The flexible operating plan is proposed to handle a situation such as damaged path, changing process during block transportation. In addition, an operational algorithm of a vacant transporter is proposed to cover the shortest path in a minimum time considering the situation of transporter rotation for practical use.

• Journal of Welding and Joining
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• 제27권5호
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• pp.42-48
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• 2009

Pipe welding is used in various ranges such as civil engineering and ship building engineering. Until now, many technicians work for pipe welding manually under harmful, dangerous and difficult conditions. So it is necessary to install automation process. For automation pipe welding, relation between welding parameters & bead shape should be considered. Using this relation, bead shape could be expected from welding parameters. FCAW was used in this study. Instead of pipe workpiece, fillet joint plate is used, which were inclined 0,45,90,135,180 degree. By analyzing between welding parameters (current, welding speed, voltage) and bead shape parameters with non-linear multiple regression, bead shape parameters could be expected. Piecewise Cubic Hermite Interpolation was used to expect smooth curved bead shape with bead shape parameters. From these processes, bead shape could be expected from welding parameters.

• Journal of Welding and Joining
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• 제8권1호
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• pp.23-30
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• 1990

The robotic welding has been adapted positively in many welding shops forthe purpose of improving the welding efficiency and liberating operators from the severe working atmosphere. But for a large-size structure with thick plates like ship-building and every kind of plants manufacturing, the application of the arc welding robots is not established yet. The reason is assumed that the conventional arc welding robots are not adaptive for multi-pass welding of thick plates whose grooves are not so accurate. As one solution to this problem, a guidance system which uses the welding arc itself as a sensor is largely used. In this study the velocity controller which changes the tip to workpiece distance for regulating the weld proposed. The proportional and integral gain of velocity controller were determined by using the computer simulation of the control system, and the simulation results compared with the experimental ones. It was revealed that the developed control system using the arc sensor principle has a good capability of tracking the weld joint, although some more studies will be needed to refine the model of arc current.

• Journal of Welding and Joining
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• 제14권6호
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• pp.58-67
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• 1996

The horizontal filet welding is prevalently used in heavy and ship building industries to join the parts. The phenomena occurring in the horizonal fillet welding process are very complex and highly non-linear, so that its analysis is relatively difficult. Furthermore, various kinds of weld defect such as undercut, overlap, porosity. excess weld metal and incomplete penetration can be induced due to improper welding conditions. Among these defects, undercut, overlap and excess weld metal appear frequently in horizontal filet welding. To achieve a satisfactory weld bead geometry without weld defects, it is necessary to study the effect of welding conditions in the weld bead geometry. For analyzing the weld bead geometry with and without weld defects in horizontal fillet welding, a mathematical model was proposed in conjunction with a two-dimensional heat flow analysis adopted for computing the melting tone in . base metal. The reliability of the proposed model was evaluated through experiments. which showed that the proposed model was very effective for predicting the weld bead shape with or without weld defects in horizontal fillet welding.

• International Journal of Precision Engineering and Manufacturing
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• 제8권4호
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• pp.50-55
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• 2007

Stereolithography (SLA) is a technique using a laser beam to cure a photopolymer liquid resin with three-dimensional computer-aided design (CAD) data, The accuracy of the prototype, the build time, and the cured properties of the resins are controlled by the SLA process parameters such as the size of the laser beam, scan velocity, hatch spacing, and layer thickness, In particular, the size of the laser beam is the most important parameter in SLA, This study investigated the curing properties of photopolymers as a function of the laser beam size, The cure width and depth were measured either on a single cure line or at a single cure layer for various hatch spacings and laser beam sizes, The cure depth ranged from 0.23 to 0.34 mm and was directly proportional to the beam radius, whereas the cure width ranged from 0.42 to 1.07 mm and was inversely proportional to the beam radius, The resulting surface roughness ranged from 1.12 to $2.23{\mu}m$ for a ratio of hatch spacing to beam radius in the range 0.5-2.0 at a beam radius of 0.17 mm and a scan velocity of 125 mm/sec.

• 한국CDE학회논문집
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• 제16권3호
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• pp.197-206
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• 2011

Shipbuilding is a complex industry which contains a lot of knowledge, technology, and utilities. Hence, the necessity of the PLM (Product Life-cycle Management) system which manages life-cycle information of marine product has been increased. So, many studies related to shipbuilding PLM have been preceded, and there are some cases to be built. To implement collaboration and concurrent engineering of ship designing and manufacturing, interoperability of product data in heterogeneous system is required. Also, sharing and reusing knowledge are important for innovation of business process and productivity of enterprises. Even though many studies related interoperability of product data are going on in varies domain, the application to shipbuilding is deficient. This paper proposes a methodology for management and interconnection of BOM data based on ontology in heterogeneous PLM system of shipbuilding. Using Prot$\'{e}$g$\'{e}$-OWL, we built simple domain ontology of shipbuilding industry, and then, we integrated product information of shipbuilding BOM which is represented with different ontologies. We verified possibility of integration of shipbuilding BOM in heterogeneous PLM, using ontology.

• 산업경영시스템학회지
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• 제30권2호
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• pp.67-74
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• 2007

The objective of this research is to select the most effective technique among task related techniques(motion & time study, job redesign, physical environment improvement) for improving work efficiency in shipbuilding enterprise. This study consists of several principal steps. The first step is to design critical criteria in evaluating work efficiency in ship-building enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP(Analytic Hierarchy Process) structure using the critical criteria, sub-criteria and techniques among task related techniques. The fourth step is to develop the pairwise comparison matrix at each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique among task related techniques using AHP analysis. The result of AHP analysis has shown clear difference in priority among task related techniques in terms of work efficiency of the shipbuilding enterprise: The reduction of normal time is more important than the reduction of allowance time in improving of the work efficiency. Motion & time study is the most important technique for the reduction of normal time, and physical environment improvement is the most important technique for the reduction of allowance time as well.