• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.865-873
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• 2013

This paper proposes a theoretical solution of elastic critical buckling load of infinitely long pipelines with non-uniform thickness under external pressure. The non-uniform cross section of pipelines can be considered as corroded or stiffened pipelines so that this paper can be a fundamental research of pipelines that are essential technology for offshore industries. The theoretical solution of pipelines with non-uniform thickness is derived with an assumption that a cylindrical shell under external pressure can be considered as a simple ring. The eigenfunctions are derived to obtain the critical buckling load. The reduced thickness and the reduced range are considered as variables in parametric analysis. The finite element analysis is performed to verify the theoretical solutions and the results of the analytic method and the finite element method are in good agreement.

• Journal of Ocean Engineering and Technology
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• v.26 no.2
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• pp.79-84
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• 2012

This study aimed to analyze the nonlinear buckling of ring-stiffened circular cylinders under uniform external pressure, e.g. hydrostatic pressure, considering material nonlinearity and initial imperfection. In the present study, we analyzed the collapse pressure of pressure vessels using ANSYS Workbench, which is a framework of finite element methods. First, linear buckling analysis is performed to find collapse modes of the model. Second, scaling the first mode shape with small factor, geometric model is pre-deformed. And then, by analyzing the nonlinear buckling of the pre-deformed shape, the collapse pressure is estimated. To verify the validity of the analyses, we compared the results with Ross' experimental results. Finally, we applied it to ring-stiffened circular cylindrical shell of the pressure hull of a small submarine.

• Journal of the Korean Institute of Gas
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• v.14 no.4
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• pp.45-50
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• 2010

The marine pipelines laid in deep waters were evaluated to verify the resistance on the plastic collapse to heavy ambient external pressure due to hydrostatic pressure. In this study, the plastic collapse behavior of the marine pipe subjected to hydrostatic pressure was evaluated with the ovality and ratio of diameter to thickness in FE analyses. A parametric study was shown that the internal pressure increased the plastic collapse depth by increasing of the resistance to the plastic collapse. It was also shown that the collapse depth of the pipeline having a local ovality was deeper than that of the pipeline having a global ovality. Finally, the plastic collapse depth decreased when either the ratio of diameter to thickness or the ovality increased.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.1-6
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• 2010

River crossing pipelines have been being operated with buried depth of 1.2~4m underneath river bottom to prevent buoyance and external impact. River crossing pipelines have to show resistance to soil load and hydrostatic pressure. In this study, structural integrity of the river crossing pipeline subjected to soil load and hydrostatic pressure was evaluated by using FE analyses. Hoop stress increased with increasing buried depth under identical water height in case of without concrete encasement, however, hoop stress decreased with increasing water height under identical buried depth.

• Conservation Science in Museum
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• v.14
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• pp.1-5
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• 2013

This study was conducted to analysis and conserve a lacquered sheath excavated from Soochon-ri, Gongju, Korea. The lacquered sheath was collected together with iron relics. The lacquered sheath was damaged and lost the parts by the external pressure. Many parts were adhered with the rust. Firstly, the object was understanded to have the relation with the iron materials excavated together through the X-ray photographs. As the analysis of the lacquer layers, the report conducted to a study the method of production. After the analysis of relic, the conservation treatment was performed for the stability of original shape. And we made the protection frame for the storage and exhibition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.142-148
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• 2009

This paper is to investigate the fracture behavior characteristics of box culvert and incremental crack width of upper slab for the incremental loading by the 3-axis loading system. In the 3-axes loading system, loading directions are upper side, left and right side which simulate earth pressure and static traffic load. With the incremental load, crack patterns is investigated on the upper slab, left and right wall. Especially, on the upper slab, crack width is measured by crack gage. Based on the experimental results, structural internal force indices of box culvert are estimated quantitatively.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.18-18
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• 2015

현재 국내 도시유역의 유출분석을 위한 많은 모형들 중에서 SWMM 모형은 지표면의 양상, 침투율, 하수관망 체계를 고려한 유출분석이 가능하고, 계산과정에서 부등류를 해석함으로써 하류관로의 배수위 영향을 고려할 수 있는 장점을 가지고 있어 도시유출해석에 많이 이용되고 있는 실정이다. 지하시설물인 하수관로는 유지관리가 어려운 시설물 중 하나이다. 지하에 위치한 하수관망도는 상부 외압에 의한 토양의 유동과 미세한 토류의 변화 등으로 지속적으로 유동이 발생하고 있는 실정이다. 또한, 육안을 통한 조사가 어려운 지하시설물이기 때문에 하수관로 정보의 유지관리가 어려운 실정이다. 맨홀은 하수관거의 제원이 변화된 지점, 흐름방향 및 경사가 급격하게 변하는 지점 등에 위치하고 있어 하수관로 정보를 관리하는 있다. 지하시설물인 하수관로는 관리가 용이하지 않기 때문에 지반침하 등으로 관거의 평균경사 등이 변경될 수 있다. 본 연구에서는 하수관로 상류 및 하류 관저고의 변화에 따른 민감도를 분석하고자 한다. 대상 유역의 모든 관로에 대한 영향을 객관적으로 검토하기 위하여 도시적인 해석을 토하여 관거정보의 오차에 따라서 유출에 미치는 영향을 분석하고 이런 문제를 해결할 수 있는 방안 들을 정리하여 향후, 하수관로 정보의 신뢰성 확보를 위하여 하수관망 정보의 정밀도 문제를 검토하는데 도움이 되고자 한다.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.2
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• pp.144-153
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• 2016

This paper aims to demonstrate the design, structure analysis, and hydrostatic pressure test of the cylinder used in 2000m water depth. The cylinder was designed in accordance with ASME pressure vessel design rule. The 1.5 times safety factor required by the general rule was applied to the design of the cylinder, because ASME rule is so excessive that it is not proper to apply to the hydrostatic pressure test. The finite element analysis was conducted for the cylinder. The cylinder was produced according to the design. The hydrostatic pressure test was conducted at the hyperbaric chamber in KRISO. The results of finite element analysis(FEM) and those of the hydrostatic pressure test were almost the same, which showed that the design was exact and reliable.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.264-270
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• 2020

Design was developed through user-oriented service design methodology and survey was conducted on material selection criteria for prototype production to select CFRP (Carbon Fiber Reinforced Plastics) CNT (Carbon Nano Tube), which was applied to animal X-ray detector panel to design product and develop prototype. Completed prototype with the application of CFRP CNT panel was tested in drop test, frontal external pressure test, and dustproof/waterproof performance to confirm that it can be utilized as a portable animal X-ray detector used in outdoor environment.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.157-157
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• 2011

프리캐스트 콘크리트 박스 암거는 현장 타설식 암거에 비해 구조물의 고품질화 및 반복적인 대량생산으로 원가 절감과 건식화 시공으로 인한 공정의 단순화와 공기가 단축되는 이점을 지니고 있다. 따라서 본 연구는 상재 허용하중을 확보하고, 시공성 및 내구성이 뛰어나며, 경제성을 고려한 고성능 프리캐스트 박스 암거를 개발하고 향후 고성능 프리캐스트 박스 암거를 생산하기 위한 기초적인 자료를 제시하고자 하였다. 본 연구에서는 기존의 보통 포틀랜드 시멘트를 이용한 프리캐스트 박스 암거의 경제성 및 내구성, 강도특성을 개선하고자 고로슬래그를 이용하여 최적의 배합비를 산출하고, 이를 토대로 중성화, 염해, 동결융해 등의 시험을 통해 내구성을 확보하고, 휨 성능을 확인하고자 실물박스암거를 제작하여 외압강도시험을 실시하였다. 또한 구조해석을 통해 응력검토를 하였다. 내구성 검토 결과, 분말도 $6,000cm^2/g$을 가진 고로슬래그 미분말을 50%로 혼입한 콘크리트가 보통 포틀랜드 시멘트를 사용한 콘크리트보다 염화물이온 투과성에 대한 저항성 및 동결융해 저항성 등 기초물성 및 내구성이 개선됨을 알 수 있었다. 박스암거에 대한 휨 시험 결과, OPC에 비해 GFSC6의 경우는 크게 구조적 성능이 떨어지지는 않는 것으로 나타났으며, 균열양상 및 연성도에서는 우수함을 나타냈다. ABAQUS에 의한 비선형 해석 결과는 시험체의 휨 거동을 잘 묘사하는 것으로 나타났으며, 처짐의 경우 시험체의 시험결과보다 크게 나타났지만, 처짐 양상은 비슷한 것을 알 수 있었고, 벽체와 상부 슬래브에 발생하는 응력은 부재가 허용하는 균열응력값 이내로 나타남에 따라 사용하중 상태에서의 응력검토는 안전한 것으로 판단된다.