• 한국해양공학회지
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• 제27권2호
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• pp.13-18
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• 2013

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. The structural design of these pipes mostly relies on the commercial code, CAESAR-II, which was especially developed for the structural analysis of pipes. This study conducted stress analyses of the same pipe unit, including loops, using both CAESAR-II and MSC/NASTRAN, and compared the results to investigate the characteristics of CAESAR-II. A parametric study was then conducted of the various design variables of pipe loops using CAESAR-II to draw some useful information about the structural characteristics of the loops.

• 한국가스학회지
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• 제22권1호
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• pp.45-52
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• 2018

이 논문에서는 도시가스 배관 중 교량에 설치된 배관 398개소에 대해 현황을 조사하고, 배관을 설치연도별, 길이별, 원격차단장치 설치여부 등 특성별로 분류하여 분석하였다. 분석결과 20년 이상 장기사용배관이 43.0%를 차지하고 있었고, 원격차단장치 미설치 교량배관은 89.4%에 달하는 등 드러난 현상에 대한 안전관리 방안을 제시하였다. 또한 조사된 교량설치 배관 중 76개소를 선정한 후 응력해석 전용프로그램인 CAESAR-II를 이용하여 응력특성을 연구하고, 교량배관 중 루프관을 설치할 경우 루프관의 위치 및 크기가 배관의 합성응력에 미치는 영향을 분석하였다. 본 연구의 결과를 통해 교량 배관의 설치, 검사 및 진단 기준 개선 등에 활용하여 교량설치 배관에 대한 안전성 향상에 도움이 될 수 있을 것으로 판단한다.

• 대한조선학회논문집
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• 제48권4호
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• pp.325-329
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• 2011

Floating, production, storage and offloading (FPSO) is a production facility that refines and saves the drilled crude oil from a drilling facility in the ocean. The flare system in the FPSO is a major part of the pressure relieving system for hydrocarbon processing plants. The flare system consists of a number of pipes and complicated connection systems. Decision of pipe support types is important since the load on the support and the stress in the pipe are influenced by the pipe support type. In this study, we optimally determined the pipe support types that minimized the support cost while satisfying the design constraints on maximum support load, maximum nozzle load and maximum pipe stress ratio. Performance indices included in the design constraints for a specified design were evaluated by pipe structural analysis using CAESAR II. Since pipe support types were all discrete design variables, an evolutionary algorithm (EA) was used as an optimizer. We successfully obtained the optimal solution that reduced the support cost by 27.2% compared to the initial support cost while all the design requirements were satisfied.

• Wind and Structures
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• 제34권2호
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• pp.231-257
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• 2022

Transmission lines systems are important components of the electrical power infrastructure. However, these systems are vulnerable to damage from high wind events such as hurricanes. This study presents the results from a 1:50 scale aeroelastic model of a multi-span transmission lines system subjected to simulated hurricane winds. The transmission lines system considered in this study consists of three lattice towers, four spans of conductors and two end-frames. The aeroelastic tests were conducted at the NSF NHERI Wall of Wind Experimental Facility (WOW EF) at the Florida International University (FIU). A horizontal distortion scaling technique was used in order to fit the entire model on the WOW turntable. The system was tested at various wind speeds ranging from 35 m/s to 78 m/s (equivalent full-scale speeds) for varying wind directions. A system identification (SID) technique was used to evaluate experimental-based along-wind aerodynamic damping coefficients and compare with their theoretical counterparts. Comparisons were done for two aeroelastic models: (i) a self-supported lattice tower, and (ii) a multi-span transmission lines system. A buffeting analysis was conducted to estimate the response of the conductors and compare it to measured experimental values. The responses of the single lattice tower and the multi-span transmission lines system were compared. The coupling effects seem to drastically change the aerodynamic damping of the system, compared to the single lattice tower case. The estimation of the drag forces on the conductors are in good agreement with their experimental counterparts. The incorporation of the change in turbulence intensity along the height of the towers appears to better estimate the response of the transmission tower, in comparison with previous methods which assumed constant turbulence intensity. Dynamic amplification factors and gust effect factors were computed, and comparisons were made with code specific values. The resonance contribution is shown to reach a maximum of 18% and 30% of the peak response of the stand-alone tower and entire system, respectively.