• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.178-186
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• 2005

In this study, the PSC girder bridge retrofitted with external tendons is tested to verify the strengthening effects. We measure the variations of the displacement and strain at mid-span of each beam as external tendons are removed in sequence. The structural behavior of the bridge are examined using controlled truck load tests for the systems before and after all external tendons were removed. From the test results, the characteristics of structural behavior of the bridge do not change significantly, but the natural frequency is decreased after the external tendons are removed. The strengthening effects of bridges can be exactly estimated by analytical methods some extent. As a result of this study, when a PSC girder bridge is deteriorated, the bridge can be retrofitted effectively by External Prestressing Strengthening Method, and the strengthening effects can be predicted through accurate structural analysis.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.419-429
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• 2009

This study focuses on the effect of the cutting order of prestressing strands on the strain change in the strands and on the state of stress of concrete, experimentally and numerically. In the experiment, strain of strands and of transversal reinforcement were measured for three different cutting orders during detensioning process by using flame-cutting procedure. The experimental results were compared with those obtained from the FE analysis. As a results of the experiment, it is confirmed that the cutting order of prestressing strands affected on the strain of strands as well as of transversal reinforcement. The FE analysis gave similar results to those obtained from the experiment. Therefore, the cutting order should be chosen appropriately to when the strands get detensioned.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.755-762
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• 2007

For the evaluation of the load carrying capacity of the deteriorated PSC I girder bridge in service load state and the verification of the grade to the reinforcement effect of actual bridge strengthened by external prestressing tendons, the field test using vehicles is applied widely. Because this teat was executed in elastic range, the investigation of the characteristics of behavior caused by live load is only available. And it is impossible to estimate load carrying capacity in limit state and nonlinear behavior after that a crack is appeared. In this study, the 27-year-old prestressed concrete girder bridge is used and various load tests are performed, so we evaluate the behavior characteristics of the bridge in service load state and ultimate load state, and estimate the load carrying capacity of bridge. In addition, the artificial damages are induced from cutting internal tendons, and external tendons is added to strengthen it as much as vanished internal tendons. Next we compare the damage state with the strengthening state. In case of the application of external prestressing method to PSC I girder bridge, the present experiment result may decide more exactly the load carrying capacity of actual bridge, the amount for reinforcement, and the standard of quality control etc. at reinforcement work.

• Journal of Korea Ship Safrty Technology Authority
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• s.32
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• pp.2-11
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• 2012

강화플라스틱(FRP)이 가진 저비용 장점에 비하여 화재 및 환경오염 문제가 대두됨에 따라서 알루미늄 소형 선박에 대한 수요가 증가하고 있다. 알루미늄 재질의 선박 건조에도 절단, 성형, 용접 및 조립의 과정이 필요하지만, 소형 선박에는 박판이 사용되기 때문에 일반 강선과는 다른 공법 및 가공 조립법이 사용된다. 본 기사는 알루미늄 재료의 절단 공법, 용접 공법의 현황과 미래 기술 방향을 정리하였다. 또한 성형 공정의 문제점과 이를 위한 개선 방안을 제시함으로써 알루미늄 선박의 건조 생산성 향상 및 정도 관리의 편의성을 위한 방안을 모색하고자 한다.

• Journal of the Korean Arthroscopy Society
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• v.3 no.2
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• pp.109-114
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• 1999

Purpose : The importance of meniscal repair is well recognized. But transeciton of the posterior horn of the medial meniscus at the posterior tibial attachment is rarely documented and known irreparable. We experienced 9 cases of transection, and present clinical features and pull out suture technique. Methods and Materials : There were 9cases of transection of the posterior horn of medial meniscus from September 1998 to July 1999 in our hospital. Age was 59.3 years in average and ranged from 38 to 70years. Clinical features and MRI made diagnosis in all cases. We confirmed the diagnosis with arthroscopy and repaired the transection with pullout suture technique. Clinical features : Transection of the posterior horn of the medial meniscus at the posterior tibia attachment occurred frequently in middle aged people. They complained posterior knee pain, but they have no history of definitive trauma. Characteristically they had difficulty in full flexion of the knee and in having a squatting position. MRI is very important in diagnosis of transection, especially in coronal view, there is separation of the posterior horn of the meniscus from the posterior tibial attachment. Surgical technique : Pullout suture technique includes debridement of fibrous or scar tissue, exposure of the subchondral bone of the posterior tibial attachment site, suture the transected end of the meniscus with PDS suture, bone tunnel formation from the anteromedial aspect of the proximal tibia, insertion of wire loop through the tibia tunnel, pull the PDS suture through the tibia tunnel out of the joint and stabilize the PDS with post-tie technique to the proximal tibia. Conclusion : Transection of the posterior horn of the medial meniscus at the posterior tibial attachment is not common clinically and rarely documented. Clinical features and MRI are very important in diagnosis of this type tear. Arthroscopic pullout sutures is useful for treatment of this type tear of the meniscus.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.388-394
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• 2018

When a ship is berthing on the pier using a mooring rope, excessive ship speeds may cause accidents where mooring rope is cut off. In order to prevent the mooring rope from breaking, there is need to know the approach speed limit of the ship. The purpose of this study is to estimate the berthing speed limit of a ship to prevent mooring fracture. Focus will be made to when the speed of the ship is unknown. In this study, we propose a method and procedure for estimating the berthing-speed limit based on the theory of ship resistance and the elasticity of the mooring rope. This method was found to be effective as it was observed that the mooring rope cannot be broken when it is estimated that the berthing-speed of a 135K LNG vessel, IWRC, and $6{\times}36$ steel wire mooring rope. The method proposed in this study will significantly contribute to preventing actual accidents related to mooring lines.