• Journal of Welding and Joining
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• 제29권3호
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• pp.58-63
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• 2011

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was compared with existing CP-type nozzle by TIG pulse welding in overhead position. As a result, CP-type occurs the wormholes in the overhead position, but the Venturi-type without the pore and formed a good bead appearance.

• 대한기계학회논문집A
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• 제40권10호
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• pp.901-906
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• 2016

본 논문은 두께 10 mm의 조선용 강판 AH36에 대해 레이저-아크 하이브리드 용접을 사용하여 원패스 관통용접을 실시함으로써 실제 조선 산업에서의 생산성 향상을 목적으로 연구되었다. 10 mm두께의 후판을 사용하였기 때문에 관통용접을 얻기 위해서는 더욱 높은 레이저 및 아크의 출력이 요구되었다. 그러나 보다 더 증가된 레이저 및 아크 출력의 사용은 비드 양단에 언더컷과 같은 결함을 야기하였다. 이러한 언더컷은 노치로 작용하여 용접 구조물의 강도를 약화시키므로 반드시 방지되어야하며, 본 실험에서는 아크의 변수인 용접 전압 및 펄스컬렉션을 조절함으로써 제어할 수 있었다. 용접된 시험편의 기계적 특성을 파악하기 위해 레이저 영역 및 아크 영역에 대해 경도 측정을 실시하였다. 그 결과, 열영향부는 조직의 변태로 인해 최대 경도가 용접부보다 높은 것을 확인할 수 있었다. 미세조직 관찰 결과, 열영향부는 마르텐사이트 및 베이나이트와 같은 경한 조직으로 구성되어 있는 것을 알 수 있었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.55-55
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• 2009

FGB(Flexible Glasswool Backing) Submerged Arc Welding has been one of the main welding processes for one side butt welding in shipbuilding industries, which can efficiently improve the welding productivity by the addition of a supplementary filler metal into the molten weld pool. As recent ships have become larger in size, the application of high tensile and higher grade of steels has been continuously increased. Single pass FGB SA welding process accompanies such a high heat input when welding thick plates that the mechanical properties of weld metal can be dramatically degraded. This study has been performed in order to obtain high toughness and tensile properties of high heat input FGB SA welds, and to evaluate the effect of alloy elements on their mechanical properties. To complete welding 25mm-thick EH36 grade steel plate by single pass, 1.2mm diameter and 1.0mm long cut wires has been distributed in the groove before welding, and three different test coupons have been made using C-1.5%Mn, C-1.8%Mn-0.5%Mo, and C-1.4%Mn-1.7%Ni cut wires to investigate the influence of nickel(Ni) and molybdenum(Mo) on the mechanical properties of welds. Test results showed that the addition of Ni and Mo effectively promotes the formation of Acicular Ferrite(AF), while significantly reducing the amount of Grain Boundary Ferrite(GBF) in weld metal microstructures, which resulted in a beneficial effect on low temperature impact toughness and strength.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4717-4722
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• 2014

조선소에서는 블록 조인트의 용접 작업 시 단차 조정 및 변형 방지의 목적으로 도그피스(Dog-Piece)를 사용하고 있는데, 조선소마다 그 규모에 따라 연간 수십만 개의 도그피스를 사용하고 있으며 설치, 제거 및 사상 작업에 투입되는 생산시수도 연간 수십만 시수에 이르고 있어 생산성 향상의 저해 요인이 되고 있다. 본 연구는 선체 블록의 정도 품질을 확보하면서 도그피스의 사용량 절감 방안을 마련하기 위한 목적으로 수행되었다. 연구 내용으로는 우선 일련의 용접실험을 통해 도그피스가 맞대기 용접시의 변형에 미치는 구속 효과를 정량적으로 검토하였고, 실험 결과를 토대로 도그피스가 부착된 맞대기 용접시의 변형을 계산하는 유한요소 해석 방법을 정립하였다. 또한, 제안된 해석 방법을 이용하여 도그피스를 고려한 선체블록 조인트의 용접변형을 시뮬레이션하고 결과를 검토하였다. 제안된 해석 방법은 향후 도그피스 배치도면 작성 및 설치 가이드 작성 등의 실질적인 도그피스 절감 방안을 마련하기 위한 해석 도구로 폭넓게 활용될 수 있다.

• 해양환경안전학회지
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• 제19권1호
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• pp.71-77
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• 2013

Smart work는 정보통신기술을 이용하여 시간과 공간의 제약 없이 언제, 어디서든 근로자가 업무를 수행할 수 있는 유연한 근무형태를 의미한다. 스마트워크의 유형에는 모바일 오피스, 홈 오피스, 센터근무, 원격협업으로 분류할 수 있다. 태블릿PC나 스마트폰을 이용한 스마트워크 방식을 모바일 오피스라고 하며, 이동통신망과 휴대 단말기를 이용한 서비스를 제공하는 방식이다. 모바일 오피스는 무선환경과 스마트기기를 이용하여 움직이는 사무실을 구현하는 것으로 언제, 어디서나 사내 시스템에 접속하여 정보 검색은 물론 결재, 승인 등의 업무를 수행할 수 있다. 이러한 모바일 오피스 시스템을 조선소에 적용한다면, 실시간 처리로 근로자들의 생산성과 업무 효율성을 향상 시킬 수 있다. 따라서 본 연구는 조선업을 위한 HSE관리 모바일 어플리케이션 개발을 위해 기능을 추출하고 설계하는 것이 목적이다. 모바일용 HSE 관리 어플리케이션을 개발하기 위해 10개의 기능들을 추출하였고, ooCBD 방법론을 이용하여 설계하였다.

• Journal of Welding and Joining
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• 제34권2호
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• pp.16-21
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• 2016

Recent keywords of the heavy industries are large-scale structure and productivity. Especially, the sizes of the commercial vessels and the offshore structures have been gradually increased to deliver goods and explore or produce oil and natural gas in the Arctic. High heat input welding processes such as electro gas welding (EGW) have been widely used for welding thick steel plates with flux-cored arc welding (FCAW), especially in the shipbuilding industries. Because high heat input welding may cause the detrimental effects on the fracture toughness of the welded joint and the heat affected zone, it is essential to obtain the sufficient toughness of welded joint. There are well known that the fracture toughness like CTOD, CVN, and KIC were very important factors in order to secure the safety of the structures. Furthermore, the welding residual stress should be considered to estimate the unstable fracture in both EGW and FCAW. However, there are no references on the welding residual stress distribution of EGW and FCAW with thick steel plates. Therefore the welding residual stresses were very important elements to evaluate the safety of the welded structure. Based on the measurement results, the characteristics of residual stress distribution through thickness were compared between one-pass electron gas welding and multi-pass flux-cored arc welding. The longitudinal residual stress in the multi-pass flux-cored arc welding is tensile through all thicknesses in the welding fusion zone. Meanwhile, longitudinal residual stress of EGW is tensile on both surfaces and compressive at the inside of the plate. The magnitude of residual stresses by electron gas welding is lower than that by flux-cored arc welding.

• 대한조선학회논문집
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• 제57권3호
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• pp.140-151
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• 2020

It is important to identify the location of ship hull blocks with exact block identification number when scheduling the shipbuilding process. The wrong information on the location and identification number of some hull block can cause low productivity by spending time to find where the exact hull block is. In order to solve this problem, it is necessary to equip the system to track the location of the blocks and to identify the identification numbers of the blocks automatically. There were a lot of researches of location tracking system for the hull blocks on the stockyard. However there has been no research to identify the hull blocks on the stockyard. This study compares the performance of 5 Convolutional Neural Network (CNN) models with multi-view image set on the classification of the hull blocks to identify the blocks on the stockyard. The CNN models are open algorithms of ImageNet Large-Scale Visual Recognition Competition (ILSVRC). Four scaled hull block models are used to acquire the images of ship hull blocks. Learning and transfer learning of the CNN models with original training data and augmented data of the original training data were done. 20 tests and predictions in consideration of five CNN models and four cases of training conditions are performed. In order to compare the classification performance of the CNN models, accuracy and average F1-Score from confusion matrix are adopted as the performance measures. As a result of the comparison, Resnet-152v2 model shows the highest accuracy and average F1-Score with full block prediction image set and with cropped block prediction image set.

• 대한조선학회논문집
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• 제45권2호
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• pp.202-212
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• 2008

In recent days, global shipbuilding companies have been increasing their productivity or expanding their shipyards for a large amount of orders. Though, few researches about the shipyard layout designs have been studied. This research presents a simulation-based shipyard layout design framework to resolve the problems of the shipyard layout design. The shipyard layout design framework was developed on the basis of systems engineering method. The disciplined system engineering technique was guided by ISO/IEC 15288 during the planning phase of the shipyard layout design framework development. This framework suggests that how efficient and effective shipyard layout design could be got, that can satisfy the stakeholder of the layout. Furthermore, it is recommended that how the proposed shipyard layout should be verified and validated by digital simulation model. It is expected that the framework will contribute to not only the improvement of the existing shipyard but also the construction of the new shipyard.

• International Journal of Naval Architecture and Ocean Engineering
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• 제1권2호
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• pp.78-88
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• 2009

In shipbuilding industry, the manufacturing technology has advanced at an unprecedented pace for the last decade. As a result, many automatic systems for cutting, welding, etc. have been developed and employed in the manufacturing process and accordingly the productivity has been increased drastically. Despite such improvement in the manufacturing technology, however, development of an automatic system for fabricating a curved hull plate remains at the beginning stage since hardware and software for the automation of the curved hull fabrication process should be developed differently depending on the dimensions of plates, forming methods and manufacturing processes of each shipyard. To deal with this problem, it is necessary to create a "plug-in" framework, which can adopt various kinds of hardware and software to construct a full automatic fabrication system. In this paper, a framework for automatic fabrication of curved hull plates is proposed, which consists of four components and related software. In particular the software module for computing fabrication information is developed by using the ooCBD development methodology, which can interface with other hardware and software with minimum effort. Examples of the proposed framework applied to medium and large shipyards are presented.

• 한국정보통신학회논문지
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• 제18권9호
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• pp.2079-2086
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• 2014

조선소에서 생산관리는 생산성 향상과 가장 밀접한 업무 중의 하나이다. 현업 생산관리자와 공정계획 엔지니어들은 상호 간의 정보 공유 미흡으로 인해 공정계획 및 공정관리에 대한 충분한 생산정보를 얻지 못한다. 본 연구에서는 생산계획과 공정관리의 요구사항 분석을 통하여 생산공정모니터링 시스템에 대한 주요 이슈를 도출하고, 콤포넌트 기반 설계 기법을 활용하여 시스템 아키텍처를 수립하였다. 제안한 시스템의 주요 기능은 블록 조립에서 안벽의장 단계까지 수립하여 생산공정현황을 시각적으로 보여 줄 뿐 아니라 공정정보 공유를 극대화하는 것이다. 본 시스템은 생산관리자에게 신뢰성 있고 정확한 생산 정보를 제시간에 제공할 수 있을 것으로 기대된다.