• 한국건축시공학회지
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• 제18권5호
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• pp.489-498
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• 2018

본 연구는 대공간 지붕철골공사의 양중공법 선정을 위한 의사결정지원모델 제안을 목적으로 한다. 이를 위해 이론적 고찰 및 전문가자문을 통해 6개의 상위요인과 19개의 하위요인으로 구성된 양중공법 선정 영향요인을 도출하였다. 이후 AHP분석을 통해 요인별 상대적 중요도를 산정한 결과, 6개의 상위요인 중 현장조건(0.237), 19개의 하위요인 중 여유공지의 유무(0.118)가 양중공법 선정에 있어 가장 중요한 영향요인으로 도출되었다. 이를 바탕으로 현장관리자가 공법대안을 평가할 수 있는 방법 및 절차를 수립하고 최종적으로 현장적합도지수를 제시해줌으로써 의사결정지원모델을 구축을 완료하였다. 구축모델의 검증을 위해 대공간 현장경험자를 대상으로 사례분석을 수행한 결과, 제시된 모델이 공법선정에 있어 유용하게 활용될 수 있을 것으로 판단되었다. 본 연구의 결과는 프로젝트 초기 공법선정 과정에서 현장관리자의 의사결정을 지원하는데 활용될 것으로 기대된다.

• 대한조선학회논문집
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• 제57권2호
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• pp.114-123
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• 2020

A high-order potential-based panel method based on Green's theorem, with piecewise-linear dipole strength on triangular panels, is formulated for the analysis of potential flow around a three-dimensional wing. Previous low-order panel methods adopt square panels with piecewise-constant dipole strength, which results in inherent errors. Square panels can not represent a high curvature lifting body, such as propellers, since the four vertices of the square panel do not locate at the same flat plane. Moreover the piecewise-constant dipole strength induces inevitable errors due to the steps in dipole strength between adjacent panels. In this paper a high-order panel method is formulated to improve accuracy by adopting a piecewise linear dipole strength on triangular panels. Firstly, the square panels are replaced by triangular panels in order to increase the geometric accuracy in representing the shape of the object with large curvature. Next, the step difference of the dipole strength between adjacent panels is removed by adopting piecewise-linear dipole strength on the triangular panels. The calculated results by the present method is compared with analytical ones for simple non-lifting geometries, such as ellipsoid. The results for an elliptic wing with zero thickness at finite angle of attack are compared with Jordan's results. The comparison shows reasonable agrements for the both lifting and non-lifting bodies.

• 한국해양공학회지
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• 제14권1호
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• pp.17-22
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• 2000

This study focuses on a simple analytical approach to calculate crane lifting forces for a sunken ship. The method takes into account the relation of lifting forces acting in wire rope slings to the inclination of the vessel including the effect of lug positions. The importance of the sunken ship salvage is explained from the statistics of ship casualties during last 15 years. Euler angles are introduced to represent the inclination of a sunken ship in developing the static force and moment equations,. Three dimensional examples with one redundant degree of freedom for a GT1500 oil tanker are analyzed and the results show that the information obtained by the method could be useful to salvors to conduct salvage work.

• 산업경영시스템학회지
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• 제36권3호
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• pp.51-62
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• 2013

We propose a method using QFD for design the hierarchical structure of AHP. This method provides definition for each area of House of Quality and design the hierarchical structure of the bottom-up QFD/AHP in which the upper hierarchy is designed through the classification of common characteristics with a focus on the lower hierarchy. Finally, we apply it to the development of an evaluation index for selecting heavy lifting service providers. This study has significance as the first instance of designing the archical structure of AHP after objectively verifying whether MECE condition, the basic requirement for AHP design, is satisfied.

• Journal of Advanced Research in Ocean Engineering
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• 제1권3호
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• pp.148-156
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• 2015

Deck plates of ships or offshore structures would make out-of-plane distortion for their thin thickness. These distortions are usually straightened by thermal straightening such as flame heating method. After thermal straightening, the blocks are lifted and moved by cranes to assemble it at dry-dock stage. After this lifting process, out-of-plane deformation again happens frequently. And then, they continuously cause quality and accuracy problems in the final dry-dock process. So, it takes more time for repair and correction working. According to preceding research, the lifting process by cranes would offset the effect on thermal straightening. The target of this study is to develop a methodology analyzing the remaining efficiency of thermal straightening after block lifting. The development was based on the assumption of yield state at straightening region. Therefore the remaining efficiency was obtained by different stiffness slope while lifting & relieving. The efficiency formula was designed using inherent strain, and we made a table of zero-efficiency by cooling speed and class rule's steels. As a result, if the stress orthogonal to straightened line is calculated during lifting analysis by FEA, the efficiency can be obtained linearly to the values in the table. Finally, even optimized carling position can be designed by considering the regional data from series project and welding region on deck.

• 한국안전학회지
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• 제12권4호
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• pp.209-213
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• 1997

Manual lifting techniques are commonly defined in terms of the postures adopted at the start of the lift. Quantitative definition is problematic, however, because the absolute joint angles adopted to lift an object are influenced by task parameters, such as the initial height of the load. The main objective of this study is to investigate the grip strength of the both hands at the initial lifting points. The survey is conducted by measuring the compression force, anthropometric data and grip strength at the lifting postures for the subjects(n=50) who is assigned to their job as usual. The experiment is peformed at the four lifting postures which involving the combination of two horizontal factors(H1 : 35 cm, H2 : 55 cm) and two vertical factors(V1 : 20~80 cm, V2 : 47~102 cm). The analysis result of lifting posture indicated that each H1-V1, H2-V1 combinations are about 60$^{\circ}$ and each H1-V2, H2-V2 combinations are about $30^{\circ}$. There are significant differences on grip strength between $60^{\circ}$ and $30^{\circ}$ stooped posture. The results of this study can be provided a method defining lifting postures at the minimum grip strength. Also, it is eliminated a hazard of the injuries which are cumulative trauma disorders(CTDs) and back pain, increased a productivity and improved a welfare of workers.

• 대한안전경영과학회지
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• 제4권2호
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• pp.11-22
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• 2002

In this study, an asymmetric lifting posture prediction model was developed, which was a three-dimensional model with 12 links and 23 degrees of freedom open kinematic chains. Although previous researchers have proposed biomechanical, psychophysical, or physiological measures as cost functions, for solving redundancy, they lack in accuracy in predicting actual lifting postures and most of them are confined to the two-dimensional model. To develop an asymmetric lifting posture prediction model, we used the resolved motion method for accurately simulating the lifting motion in a reasonable time. Furthermore, in solving the redundant problem of the human posture prediction, a moment weighted Joint Range Availability (JRA) was used as a cost function in order to consider dynamic lifting. However, it is known that the moment weighted JRA as a cost function predicted the lower extremity and L5/S1 joint motions better than the upper extremities, while the constant weighted JRA as a cost function predicted the latter better than the former. To compensate for this, we proposed a hybrid moment weighted JRA as a new cost function with moment weighted for only the lower extremity. In order to validate the proposed cost function, the predicted and real lifting postures for various lifting conditions were compared by using the root mean square(RMS) error. This hybrid JRA reduced RMS more than the previous cost functions. Therefore, it is concluded that the cost function of a hybrid moment weighted JRA can be used to predict three-dimensional lifting postures. To compare with the predicted trajectories and the real lifting movements, graphical validations were performed. The results also showed that the hybrid moment weighted cost function model was found to have generated the postures more similar to the real movements.

• 한국항공우주학회지
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• 제41권12호
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• pp.931-939
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• 2013

본 논문에서는 항공기 날개의 개념 설계에서 적용하기에 적합한 양력선 방법을 찾고 정확성과 적용범위를 분석한다. Prandtl의 양력선 이론에서 발전된 두 가지 양력선 방법으로서 얇은 익형의 가정을 갖고 3/4 시위의 제어점에서 속도경계조건을 부여하는 Weissinger방법과 3차원 와류 양력법칙을 적용한 Phillips의 방법을 택하였다. 계산 대상은 타원형 날개, 후퇴각이 있는 날개, 그리고 상반각과 비틀림이 있고 후퇴각 없는 테이퍼 날개이다. 계산을 통해 포텐셜 유동의 공력 데이터로 날개의 순환분포, 내리흐름 분포, 양력과 유도항력을 추출하여 이론식 결과 및 풍동시험 데이터와 비교하였다. Weissinger 방법은 날개의 형상에 상관없이 정확도와 신뢰성 있는 결과를 보여주지만 Phillips 방법은 후퇴각이 있는 날개에서는 부정확한 결과를 나타내었다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2001년도 학술대회지
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• pp.228-231
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• 2001

부산종합운동장 주경기장 지붕구조는 케이블현수구조로 그 시공은 VSL 리프팅시스템을 사용한 인양공법을 채택하여 이루어 졌다. 본 지붕구조물의 시공은 크게 5단계 공정으로 이루어 졌고, 상기 공정 중 인양작업은 상부케이블과 하부케이블로 나누어 1차 인양작업과 2차 인양작업으로 이루어 졌다. 본 지붕구조물의 경우 각 케이블의 정착단은 조정이 불가능한 개방소켓으로 되어 있어 설계시 각 케이블의 길이 계산이 잘못될 경우에는 케이블이 구조부재로써 소정의 성능을 유지하기 위해 필요한 인장응력의 도입이 불가능하게 된다. 그러나, 구조물의 인양이 완료된 상태에서 계측된 각 케이블의 장력에 의하면 평균 $4\%$정도의 정확도를 보이고 있어 설계뿐만 아니라 지붕구조와 관련된 모든 공정의 시공이 치밀하게 이루어 졌음을 보여 주고 있다.

• 대한안전경영과학회지
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• 제16권3호
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• pp.231-237
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• 2014

Construction of the external wall framing using construction Gang-Form withstand the load of a full lift safety is very important in lifting rings can be a lot of Gang-Form is now fixed in the manner that you are welding and applied, but this study is based on the safety of the lifting ring to seek improvements were bolt type fixing method applied to the bonding type were part of the lifting ring in a manner fixed to the concrete surface and was applied in consideration of safety.