• 산업공학
• /
• 제14권3호
• /
• pp.218-226
• /
• 2001

Scheduling for shipbuilding processes has many alternative solutions since it has long time horizon and handles many jobs. This requests the scheduling system to generate and search feasible alternative solutions in short period of time. Among shipbuilding schedules, the ship erection schedule in a dock is the most important since the dock is the most critical resource in shipyard. In this research, we model the erection scheduling problem for shipbuilding and develop a new problem solving method using CST(Constraint Satisfaction Technique) and ILOG Scheduler. Experimental results show that the proposed scheduling method outperforms the existing manual scheduling methods in terms of schedule performance and required time.

• 해양환경안전학회지
• /
• 제28권7호
• /
• pp.1267-1273
• /
• 2022

최근 한국 조선업계가 세계 선박 발주 물량의 대부분을 수주하고 있지만, 생산 현장에서는 인력난으로 생산공정 차질을 겪고 있다. 오랜 조선업 불황으로 일감과 임금 모두 줄어든 탓에 근로자들이 조선소를 떠났기 때문이다. 수주가 증가한 주요 요인은 카타르 LNG선 대량 발주였으며, 선박에 요구되는 기술 사양이 복잡해지는 상황도 유리하게 작용하고 있다. 선박은 계약한 인도 시점이 무엇보다도 중요하기 때문에, 조선소의 주요 공정 중 도크 진수 계획이 무엇보다도 중요한 관리 아이템이다. 도크에서 건조되는 구조물은 의장 작업을 남긴 선체 혹은 완성형 선박일 수 있으며, 때에 따라서 선체의 일부 블록 수준일 경우도 많다. 진수 시, 선체는 유체력에 의한 호깅(hogging) 혹은 새깅(sagging) 모멘트 영향을 받게 되고, 블록 연결부의 구조강도에 대한 안전성 확보가 무엇보다도 중요하다. 정상적인 공정이라면 연결 부재는 용접을 끝낸 상태에서 진수하지만, 실제 조선사에서는 도크 일정을 준수하기 위하여 구조 안전성이 확보되는 조건에 대한 빠른 의사결정이 필요하다. 본 연구에서는 앞서 언급한 문제점들을 엔지니어링 관점에서 합리적으로 판단하기 위하여 휨 응력평가법과 유한요소해석 모델링을 사용한 상세 해석법과 적용성을 분석하였다. 논문에서 언급된 주요 내용은 향후 유사 구조 강도 평가의 진행 시 좋은 사례로 활용될 수 있을 것으로 생각한다.

• Journal of Ship and Ocean Technology
• /
• 제10권2호
• /
• pp.37-44
• /
• 2006

The erection in shipbuilding is the process to assemble all the blocks one by one in certain order and requires more leveled and efficient schedule than other processes do. However, erection schedule includes too many constraints to be systemized with simple programs and constraints are changed frequently. These difficulties make it rare to find automatic erection schedule generation system with load leveling ability. In this paper, a CSP (Constraint Satisfaction Problem)-based load leveling algorithm using a maximum load diminution technique is proposed and applied to the block erection scheduling of a dock in a shipyard. The result shows that it performs better than currently used scheduling method based on empirical logics. The maximum load of welding length and crane usage are reduced by 31.63% and 30.00% respectively. The deviation of resource usage amount also decreases by 8.93% and 7.51%.

• 대한조선학회논문집
• /
• 제41권5호
• /
• pp.55-62
• /
• 2004

The logistics of entire shipbuilding process are integrated during the block erection process and the schedules for the erection process are made prior to. the schedules of any other processes. Therefore, efficient scheduling of the block erection process are one of most important issues in shipbuilding. There are only a few studies published regarding block erection scheduling methods because of its complexity and variability. This paper proposes an algorithm for diminution of maximum load based on constraint satisfaction technique. it is developed primarily for the efficiency in load leveling and applicability to the actual block erection process. The proposed algorithm is applied to actual block erection process and the results shows improvements in load leveling. It can also be used for the scheduling of fabrication, sub-assembly, and assembly to improve load leveling.

• 대한조선학회논문집
• /
• 제43권2호
• /
• pp.228-235
• /
• 2006

Nowadays, digital manufacturing has been known to be very effective method in manufacturing fields. It is aimed to estimate process time, to improve operation efficiency, and to prevent bottleneck processes in advance of real manufacturing. This paper addresses a scheduling support system for panel hues in a shipyard through digital manufacturing simulation. The proposed system supports operators to make better decisions on the shop-floor scheduling in panel lines. It ,would provide a complete schedule that is at least as good as any schedule currently obtained. Furthermore, it can evaluate the operator's schedule by simulating it with 3-dimensional models before the work orders and schedules are released.

• 대한조선학회논문집
• /
• 제45권6호
• /
• pp.703-709
• /
• 2008

In the shipyard, line heating and triangle heating are two major processes for forming curved plates in various shapes. While there have been many studies on line heating, triangle heating has been rarely studied due to its complicated heating process with irregular multi-heating paths and highly concentrated heat input. As the triangle heating process is one of the most labor-consuming jobs in shipyards, it is essential to study the automation as well as improvement of triangle heating process in order to increase hull forming productivity. In this study, a pioneering attempt to simulate triangle heating was made. A circular disk-spring model was proposed for elasto-plastic analysis procedure of triangle heating and the inherent strain method was also used to analyze the deformation of plates. Simulation results were compared with those of experiments and showed good agreement. It is shown that the present approach including analysis model used in this study is effective to simulate the triangle heating for plate forming process in shipbuilding.

• 한국정밀공학회지
• /
• 제16권11호
• /
• pp.22-35
• /
• 1999

The block assembly process takes more than half of the total shipbuilding processes. Therefore, it is very important to have a practically useful block assembly process planning system which can build plans of maximum efficiency with minimum man-hours required. However, the process plans are often not readily executable in the assembly shops due to severe imbalance of workloads. This problem arises because the process planning is done on block by block basis in current practice without paying any attention to the load distribution among the assembly shops. this paper presents the development of an automated hull block assembly process planning system which results in the most effective use of production resources and also produces plans that enable efficient time management. If the load balance of assembly shops is to be considered at the time of process planning, the task becomes complicated because of the increased computational complexity. To solve this problem, a new approach is adopted in this research in which the load balancing function and process planning function are iterated alternately providing to each other contexts for subsequent improvement. The result of case study with the data supplied from the shipyard shows that the system developed in this research is very effective and useful.

• 한국정밀공학회지
• /
• 제14권10호
• /
• pp.75-84
• /
• 1997

This paper describes the development of an integrating method for process planning and scheduling activities for block assembly in shipbuilding. A block is composed of several steel plates and steel sections with the predetermined shapes according to the ship design. The parts which constitute the block are manufac- tured by cutting and/or bending operations, which are termed as machining operation in this paper. The machining operation is the first process for block assembly which influences the remaining block assembly processes. Thus process planning and scheduling for machining operation to manufacture parts for block are very important to meet the assembly schedule in the shipyard. An integrating method for process plan- ning and scheduling is developed by introducing the concept of distributed process planning and scheduling composed of initial planning, alternative planning and final planning stages. In initial planning stage, nesting parts information and machining emthods are generated for each steel plate. In alternative plan- ning stage, machine groups are selected and workcenter dispatching information is generated. In final planning stage, cutting sequences are determined. The integrated system is tested by case study. The result shows that the integrated system is more efficient than existing manual planning system.

• 한국산학기술학회논문지
• /
• 제17권10호
• /
• pp.426-431
• /
• 2016

근래 조선소의 해양 프로젝트 비중이 증가함에 따라 작업 안전 환경과 공정 모니터링에 대한 요구 사항이 강화되고 있다. 이에 주요 조선소에서는 IT 기술을 접목하여 공정을 실시간으로 모니터링하고 작업자의 안전을 위해 작업 환경을 감지하기 위한 연구가 진행되고 있다. 조선소의 안벽 공정은 진수 후 안벽에 다수의 선박을 계류하고 선박 내부에서 의장 시스템 등의 마무리 공사 위주로 진행되며, 동시에 1,000여명 이상이 투입되어 진행되므로 인원의 관리와 안전 환경의 관리에 어려움이 많다. 본 연구에서는 이러한 안벽에서의 안전 작업을 위한 작업 환경을 모니터링하고 공정 진행 상황을 감지하기 위한 시스템의 개념 설계를 수행하였다. 현장 적용성을 높이기 위해 초기 투자비와 유지 운영비를 고려하여 6가지 구성 요소로 전체 시스템을 구성하였으며, 조선소 현장의 통신 환경을 고려하여 Wi-Fi와 LoRa 통신을 혼용하였고 현장에서의 데이터 송수신 기초 실험을 통해 그 적용성을 확인하였다. 설계된 시스템의 적용을 통해 안벽에 계류된 선박의 작업에 투입된 인원 현황, 작업 구역별 안전 현황을 실시간으로 감지하고 이를 기반으로 위험 상황 발생 시 단계별 알람을 발생하여 신속한 대피 및 대처가 가능하도록 함으로써 인명 손실 및 피해를 최소화 할 수 있다.

• Journal of Radiation Protection and Research
• /
• 제31권2호
• /
• pp.69-89
• /
• 2006

Biological mechanisms for ionizing radiation effects are different at low doses than at high doses. Radiation hormesis involves low-dose-induced protection and high-dose-induced harm. The protective component is associated with a reduction in the incidence of cancer below the spontaneous frequency, brought about by activation of defensive and repair processes. The Linear No-Threshold (LNT) hypothesis advocated by the International Commission on Radiological Protection (ICRP) and the Biological Effects of ionizing Radiation (BEIR) Report VII for cancer risk estimations Ignores hormesis and the presence of a threshold. Cancer incidences significantly less than expected have been found in a large number of epidemiological studies including, airline flight personnel, inhabitants of high radiation backgrounds, shipyard workers, nuclear site workers in scores of locations throughout the world, nuclear power utility workers, plutonium workers, military nuclear test site Participants, Japanese A-bomb survivors, residents contaminated by major nuclear accidents, residents of Taiwan living in $^{60}Co$ contaminated buildings, fluoroscopy and mammography patients, radium dial painters, and those exposed to indoor radon. Significantly increased cancer was not found at doses <200 $mSv^*$. Evidence for radiation hormesis was seen in both sexes for acute or chronic exposures, low or high LET radiations, external whole- or partial body exposures, and for internal radionuclides. The ubiquitous nature of the Healthy Worker Effect (HWE)-like responses in cellular, animal and epidemiological studies negates the HWE as an explanation for radiation hormesis. The LNT hypothesis is wrong and does not represent the true nature of the dose-response relationship, since low doses or dose-rates commonly result in thresholds and reduce cancer incidences below the spontaneous rate. Radiation protection organizations should seriously consider the cost and health implications of radiation hormesis.