• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.5-16
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• 2015

In the long span bridge construction, construction cost portion of large scale marine foundation is about 40% (KICTEP, 2007). In this study, designs for deep water depth large composite foundation of a super long span cable-stayed girder bridge of prototype were performed by three design methods (ASD, LRFD, Eurocode) and the behaviors of a large diameter drilled shaft were analyzed and the 3D numerical analysis was performed. As a result, the soft rock socket lengths in allowable stress design estimation method were the longest. The soft rock socket lengths estimated by the design approach 2 among Eurocode and the LRFD were similar. The longer the socket length socketed in the soft rock was, the smaller the axial force acting on a large-diameter drilled shaft head was and the smaller the settlement of drilled shaft was.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.1-8
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• 2014

This paper deals with monitoring and analysis of temperature measurement data in concrete pylon of long span cable bridges. During the construction of Geoga Bridge in Busan-Geoje Fixed Link Project, temperature sensors were installed in several sections of hollow box type concrete pylon and temperatures along the depth of the four sides of the section have been recorded along with ambient temperature. Effects of temperature distribution on the pylon are analysed using actual measured data and results are compared with the design guideline. It was found that the temperature load model for concrete girder can be applied to box type concrete pylon. Structural analysis of the pylon due to variation of temperature distribution during the construction is performed using 3D modelling and FE program and the maximum displacements of east-west and north-south side were calculated as 0.056m and 0.121m, respectively.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1614-1616
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• 2011

지중송전라인에서 전압등급의 상승은 선로손실을 줄이면서 밀집된 전력수요에 대응하거나 특별히 고전압 수요를 맞추기 위한 것으로 이것은 XLPE Cable의 제조기술이 향상되면서 지속적으로 진행되어온 초고압송전계통의 일반적 추세이다. 이러한 경향으로 해외에서는 케이블 도체의 송전용량을 증대시킬 수 있는 방법으로 케이블 도체에 에나멜 코팅을 하여 집합을 한다. 그러므로써 기존 케이블에서 발생되는 표피현상 및 근접효과에 의한 AC 저항 요소를 줄여 요구하는 전류용량을 기존 비소선절연 케이블에 비해 더 많이 송전할 수 있다. 하지만, 소선절연 케이블이 전류 용량을 증대 시킬 수 있는 장점은 있으나 접속재의 경우 도체의 에나멜 코팅을 제거해야 하는 문제점이 있다. 당사는 에나멜 코팅을 제거하는 방법을 개발 완료함으로써 본 접속재의 개발을 앞당길 수 있었다. 당사는 쿠웨이트 400kV MEW/C/3931 Project에 400kV XLPE 1C${\times}$2500SQ 소선절연 초고압송전라인을 적용하였는데 본고에서는 여기에 적용된 400kV XLPE 1C${\times}$25000SQ 소전절연 케이블 부속재의 신뢰성을 높이기 위한 설계방법, 시험 및 시공에 대하여 요약하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.5
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• pp.60-67
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• 2007

In this paper, a simulation method of the internal winding fault is proposed to calculate winding current and electromagnetic force in a distribution power transformer by suing FEM program. The model of the transformer is a single phase, 60[Hz], 1[MVA], 22.9[kV]/220[V], cable-type winding. The short-circuit current and electromagnetic force are calculated by FEM(Finite Element Method) program(Flux2D) and the results we verified with theoretical formula and PSPICE program. The simulation results are fairly good agreement with the other verified methods within 5[%] error rate. The turn-to-turn short-circuit current is 500 times of the rated current and the electromagnetic force is about $20{\sim}200times$. The method presented in this study may serve as one of the useful tools in the electromagnetic force analysis of the transformer winding behavior under the short circuit condition for design of the structure.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.393-401
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• 2009

The flexural-stiffness formula of the wale for the innovative prestressed support (IPS) system was precisely derived, and the equivalent beam stiffness was introduced for application in the actual design of the IPS wale. The cable tension forces of the IPS wale were calculated in both cases, and the axial-deformation effects were included and ignored, respectively. The central displacements of the 1-post, 2-post, 3-post, and 4-post IPS wales were calculated based on the principle of virtual work. The effects of the IPS wale length and cable inclination angle were also investigated using the derived central displacements. The simplified equivalent flexural stiffness of the IPS wale is presented herein for design purposes, and the validity of the proposed design formula was verified through its comparison with the FE and analysis solutions.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.83-92
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• 2013

Backfill material with thermal resistivity which has $50^{\circ}C$-cm/Watt in wet and $100^{\circ}C$-cm/Watt in dry is requested to improve the power transfer capability for dissipation of heat production in underground power cables. In the field test performed by buried cable backfills, the backfill material developed from this study is compared with river sand and weathered soil (native soil) to investigate the effect of heat transfer in various seasons and locations of thermal sensors. As a result, the developed backfill material is faster approaching yielding temperature (critical heat) than that of river sand and weathered soil, and it has good dissipation capacity rather than other materials by keeping moisture content at dry season.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.101-105
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• 2001

For high voltage XLPE power cables, semiconducting layers have been applied to prevent discharge at the interface between conductor and insulation, and/or insulation and external shielding layer. The semiconducting layers may be also effective to release electrical stress in the interface. The property of semiconducting layers are significantly related to the quality and reliability of power cables. Generally, these semiconducting layers are formed by extruding, the conductibility of the material is given by the carbon black mixed with base polymer. The life of power cables is depended on the smoothness of the interface between insulation and semiconducting layer. If the smoothness is no good, the life of power cables is shorter because the electrical stress and water tree is increased. The causes of no good smoothness are the void of the interface, the protrusions, the contaminants and impurities of the semiconducting layer. The selection and dispersion of the Carbon Black is the significant factor to determine the life of power cable in the manufacturing of semiconducting compound.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.10a
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• pp.40-41
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• 2009

In general, ships are towed to keep the safe operations in harbor or channel by tug boats. Due to increase in ocean traffic, many accidents are happened in harbor or channel in these days. Therefore it is necessary to predict manoeuvrability of tug-barge system, and to assure the safety of that system. Turg-barge system is composed of tug boat, barge, and towing cable, connecting both ships. Manoeuvring equations of tug-barge system are suggested, and the scopes of model tests are discussed to establish the mathematical models for tug boats in this paper.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.23-27
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• 2011

Due to the rapid development of construction technology with effective land utilization in this nation, many tunnels were and are being built across the country. However, the smoke and the heat generated from tunnel fire are the most important critical factors which may results in both massive personal injury and property damage, especially, due to the closed surrounding of the tunnel. Considering this particular nature of the tunnels, this study aims to install a fire detection system using an optic fiber cable to measure the temperature changes, compare, and analyze the resulted values with the times of temperature changes of the sensor by performing fire simulations under the same condition as a real fire test. From the results, it has been found that the temperature sensor detects a fire occurrence and generates an alarm within one minute after ignition for both a real fire test and a fire simulation alike, and also that the characteristics of temperature changes of the sensor has close relations with the speeds of the currents inside the tunnel. In addition, considering the tunnel fires can affect the evacuation efficiency and the fire extinguishing activities of the fire brigade inside the tunnel, the temperature sensor must be able to search and find the locations and directions of the fires correctly.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1322-1331
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• 2006

Concurrency control is one of the important factors to maintain consistent conditions of a game because most participants of the game should be shared information to play the game through a distributed network system. replay delay times should establish in every event and the received event should be saved and performed simultaneously for Concurrency Control. However, it is not easy to practice the event with same speed in environment having various moving speed. Therefore, expansion have to be provided. In other words, one of the most important factors of a game's efficiency is the process of bandwidth and delay. the process of concurrency control method based on scalable prediction for Multi-platform games would minimize the loss rate of a event and then would improve the interaction capacity of a game. It also might get reliability between clients. This paper analyzes some problems in terms of a layout of a game that integrates a cable and a wireless system. In addition, this paper provides methods to expand bandwidth and delay that might be an obstacle of a On-line game and to ensure reliability between a server and a client.