• Structural Engineering and Mechanics
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• 제51권5호
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• pp.707-725
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• 2014

In order to improve the crane-hook's performance and service life, we formulate a multi-criteria shape design problem considering practical conditions. The structural weight, the displacement at specified points and the induced matrix norm of stiffness matrix are adopted as the evaluation items to be minimized. The heights and widths of cross-section are chosen as the design variables. The design variables are expressed in terms of shape functions based on the Gaussian function. For this multi-objective optimization problem with three items, we utilize a multi-objective evolutionary algorithm, that is, the multi-objective Particle Swarm Optimization (MOPSO). As a common feature of obtained solutions, the side views are tapered shapes similar to those of actual crane-hook designs. The evaluation item values of the obtained designs demonstrate importance of the present optimization as well as the feasibility of the proposed optimal design approach.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 추계학술발표 개요집
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• pp.74-76
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• 1994

• 해양환경안전학회지
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• 제21권1호
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• pp.91-96
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• 2015

본 연구에서는 크레인 작업시 발생하는 재해발생 사례를 토대로 호이스트의 중량물 이탈 방지에 대한 연구를 수행하였으며, 안전고리의 결합으로 구성된 종래의 체결방식을 벗어나 구조물의 무게에 의한 자동 체결 및 결합 방식의 후크 및 특수목적을 가진 X-jog를 설계 및 제작하여 현장에 적용하고자 하였다. 주요 기구부의 3차원 상세설계와 구조해석을 통해 Safety Hook와 X-jog의 미소변형과 허용응력 이하의 구조안정성을 확인하였으며, 안전율은 일반적인 구조설계시 고려되는 안전율 1.2를 상회하는 평균 1.5를 나타냄을 확인하였다. 따라서, 본 연구에서의 Safety Hook와 X-jog는 구조물이 호이스트와 크레인에 부착되어 운용되어질시 구조적 안정성은 충분할 것으로 판단된다.

• 비파괴검사학회지
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• 제24권1호
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• pp.38-44
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• 2004

본 연구에서는 크레인 훅을 광탄성 재료의 일종인 '포토플렉스'를 이용, 2차원으로 모델링하여 힘을 가하였을 경우, 최대 압축 및 인장 응력이 발생되는 선상에서 광탄성실험법, 단순 곡선보 이론 및 유한요소법을 이용하여 응력을 측정하고 계산하였다. 특히, 광탄성 실험은 재래식 측정법에 의한 타디보간법, 프릭지 세선처리법 그리고 최근 개발된 4단계 위상이동법 등 세 가지 방법을 이용하였다. 광탄성 4단계 위상이동범은 주응력 방향, 즉 등경선이 일정한 선상에서는 연속적인 응력분포를 얻을 수 있는 장점이 있다. 크레인 훅에서 주응력 방향이 일정한 선상에 발생된 응력은 3가지 서로 다른 광탄성 실험법에 의해 측정된 길과가 잘 일치하였다 광탄성법에 의한 결과는 훅의 끝단 부근을 제외하고는 단순곡선보 이론이나 유한요소 해석결과와 대체적으로 비슷하였으나, 정확히 일치하지는 않았다. 이러한 차이는 크레인 훅의 실제 시편의 곡률등 형상과 하중조건이 단순곡선보 이론이나 유한요소 모델링 형상과 약간 다르기 때문에 나타난 것으로 추정된다. 광탄성실험법은 형상이 불규칙하고 하중조건이 복잡할 경우 실제 발생되는 응력을 전체적으로 정밀하게 측정할 수 있으므로 응력해석에 대한 이를 및 수치해석 법을 검증하는데 활용될 수 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권1호
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• pp.95-102
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• 2018

This paper proposes a dual lifting and its cooperative control system with two different kinds of floating cranes. The Mega-erection and Giga-erection in the ship building are used to handle heavier and wider blocks and modules as ships and off-shore platforms are enlarged. However, there is no equipment to handle such Tera-blocks. In order to overcome the limit on performance of existing floating cranes, the dual lifting is proposed in this research. In the dual lifting, two floating cranes are well-coordinated to add up the lift capabilities of both cranes without any loss such that virtually a single crane is lifting, maneuvering and unloading. Two main constraints for the dual lifting are as follows: First, two barges of floating cranes should be constrained as a rigid body not to cause a relative motion between two barges and main hooks of the two cranes should be controlled as main hooks of a single crane. In order words, it is necessary to develop the cooperative control of two floating cranes in order to sustain a center of gravity of the module and minimize the tilting angle during the lifting and unloading by the two floating cranes. Two floating cranes are handled as a master-slave system. The master crane is able to gather information about all working conditions and make a decision to control the individual hook speed, which communicates the slave crane by TCP/IP. The developed control system has been embedded in the real floating crane systems and the dual lifting has been demonstrated five times at SHI shipyard in 2015. The moving angles of the lifting module are analyzed and verified to be suitable for hoisting control. It is verified that the dual lifting can be applied for many heavier and wider blocks and modules to shorten the construction time of ships and off-shore platforms.

• 한국안전학회지
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• 제10권3호
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• pp.47-55
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• 1995

We got operational safety limit angle being able to affect operators or materials surrounding the center of vertical line of the hoist on working from the theoretical review and experimental result. Then we inferred the distance to about 1.2m-1.4m from the center which materials hanged on the hook were able to effect to the surround. Therefore, we got about $7^{\circ}$ to the inclined or crossed operational safety limit angle of the crane with 6m lift. Also, we developed heisting rope automatic vertical controller which could control this kind of dangerous operation. And we did experiments again after establishing the inclined or crossed operational safety limit to $7^{\circ}$. The result is satisfied.

• Safety and Health at Work
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• 제1권1호
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• pp.43-50
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• 2010

Objectives: The objective of this study was to investigate the effect of chain installation condition on stress distribution that could eventually cause disastrous failure from sudden deformation and geometric rupture. Methods: Fractographic method used for the failed chain indicates that over-stress was considered as the root cause of failure. 3D modeling and finite element analysis for the chain, used in a crane hook, were performed with a three-dimensional interactive application program, CATIA, commercial finite element analysis and computational fluid dynamic software, ANSYS. Results: The results showed that the state of stress was changed depending on the initial position of the chain that was installed in the hook. Especially, the magnitude of the stress was strongly affected by the bending forces, which are 2.5 times greater (under the simulation condition currently investigated) than that from the plain tensile load. Also, it was noted that the change of load state is strongly related to the failure of parts. The chain can hold an ultimate load of about 8 tons with only the tensile load acting on it. Conclusion: The conclusions of this research clearly showed that a reduction of the loss from similar incidents can be achieved when an operator properly handles the installation of the chain.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1210-1215
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• 2002

The spent fuel handling tool is used to handle the refuel bundle and treated by hoist rope on the bridge crane. The new developed handling tool of NPP(Nuclear Power Plant) should be conformed the structural stability under earthquake condition. In this study, the stress and seismic analysis of the handling tool are performed by finite element method. Using the Floor Response Spectrum(FRS) obtained through the time history analysis, the modal and seismic analysis under Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE) load conditions are carried out. Total 4 cases of different locations of the trolly and the hook are investigated. With the spring-damper element, the tension analysis of hoist rope is conducted. The stability of handling tool under earthquake load condition is conformed with regulatory guide.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.746-751
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• 2003

A method of measuring the length of defects on the wall of the spent nuclear fuel pool using the image processing and a laser slit beam is proposed. Since the defect monitoring camera is suspended by a crane and hinged to the crane hook, the camera viewing direction can not be adjusted to the orientation that is exactly perpendicular to the wall. Thus, the image taken by the camera, which is horizontally rotated along the axis of the camera supporting beam, is distorted and thus, the precise length can not be measured. In this paper, by using the LASER slit beam generator, the horizontally rotated angle of the camera is estimated. Once the angle is obtained, the distorted image can be easily reconstructed to the image normal to the wall. The estimation algorithm adopts a 3-dimensional coordinate transformation of the image plane where both the laser slit beam and the original image of the defects exist. The estimation equation is obtained by using the information of the beam projected on the wall and the parameters of this equation are experimentally obtained. With this algorithm, the original image of the defect taken at arbitrary rotated angle can be reconstructed to an image normal to the wall. From the result of a series of experiments, the accuracy of the defect is measured within 0.6 and 1.3 % error bound of real defect size in the air and underwater, respectively under 30 degree of the inclined angle of the laser slit beam generator. Also, the error increases as the inclined angle increases upto 60 degree. Over this angle, the defect length can not be measured since the defect image disappears. The proposed algorithm enables the accurate measurement of the defect length only by using a single camera and a laser slit beam.

• 한국해양공학회지
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• 제23권1호
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• pp.104-108
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• 2009

As the demands of ocean resource development increase, many offshore structures are required. To cope with the active ocean developments, many types of construction methods have been applied for offshore facilities, including oil, gas and harbors. One of the challenges is to transport and install the heave bridge caisson. Several construction methods are well understood. However, for the sake of safety and reliability, the F/D installation method can be utilized. While the caisson is carried by an F/D, the mooring force of the tug boat and the structure stability from exiting motions in the dock should be checked against external loadings and sea conditions. The external loads can be classified with wind force, current force, and wave force. In the stability analysis, transportation velocity and draft of F/D are important factors. The dynamic stability and hook load for crane barge installation for the same caisson are also studied. Considering external loads and dominant factors, the stability of caisson during transportation has been investigated.