• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.808-813
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• 2005

Structural integrity assessment of defected pipe is important in fitness for service evaluation and proper engineering assessment is needed to determine whether pipelines are still fit for service. This paper present a failure prediction of gas pipes made of APIl X65 steel with gouge using stress-modified true fracture strain, which is regarded as a criterion of ductile fracture. For this purpose, API X65 pipes with gouge are simulated using elastic-plastic FE analyses with the proposed ductile failure criterion and the resulting burst pressures are compared with experimental data. Agreements are quite good, which gives confidence in the use of the proposed criteria to defect assessment fer gas pipelines. Then, further extensive finite element analyses are performed to obtain the burst pressure solution of pipes with gouge as a function of defect depth, length and pipeline geometry.

• 한국해양환경ㆍ에너지학회지
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• 제3권2호
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• pp.18-24
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• 2000

성질이 다른 두가지 유체가 복잡한 상호작용을 하는 경우의 유동을 살펴 보기 위하여 2차원 비점성 수치해법을 개발하고, 이를 감압된 수중 파이프에서의 기름 유출 문제에 적용하였다. 두 유체의 경계면은 보오텍스 쉬트로 모델링하고 보오텍스격자법 (vortex-in-cell method)을 적용하여 유동을 해석하며, 장시간의 유동 모사를 위하여 경계면의 분할과 접합이 가능하도록 하였다. Boussinesq 가정에서 외부유체의 관내로의 유입 속도가 기존의 수학모델과 거의 동일함을 확인하였고, 경계면에서의 복잡한 상호 유입과 보오텍스 유동에도 불구하고 Lock Exchange가 발생함을 보였다. 개발된 수치해법은 다양한 해양환경의 2상유체 문제에 효과적으로 이용될 수 있다고 사료된다.

• 한국지반환경공학회 논문집
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• 제14권2호
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• pp.5-11
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• 2013

본 연구에서는 수중 가압식 매립방법을 이용하여 석탄회를 주재료로 하는 저강도 고유동화재(CLSM)를 대상으로 매립재 고밀도화 가능성에 대한 모형시험을 수행하고 그 결과를 분석하였다. 배출압에 의한 밀도 변화는 저강도 고유동화재를 구성하는 매립회와 비회의 배합비에 큰 영향을 받고 배출관의 위치에 따라서도 큰 영향을 받는 것으로 나타났다. 수중에서 가압 배출하는 경우, 배출관 주변을 중심으로 단위중량이 상대적으로 큰 것으로 나타나 배출압으로 인한 주변지반 밀도 증가효과가 발생하는 것으로 나타났으며, 실제 매립현장에서도 배출압의 효과를 이용할 수 있을 것으로 판단된다.

• Tribology and Lubricants
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• 제15권4호
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• pp.297-303
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• 1999

O-rings in automotive engines are important components such as a coolant pipe, engine oil circulating lines and fuel injector for sealing that makes efficient performance of the engine. Life cycle of O-rings is effected in environments of the O-ring seal, like that applied pressure, working temperature, precompressed ratio and materials. It is related in extrusion, expansion and fatigue failure of O-rings. In this paper, an pressurized, compressed elastomeric O-ring inserted into a rectangular groove is analysed numerically using the nonlinear finite element method. The calculated FEM results showed that extrusion ratio and contact stress are strongly related to the gap clearance and edge radius of the groove.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.159-164
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• 1993

This paper presents a computer design program for In-Core Instrumentation(ICI) guide tube routing and locations on support system, and checking the interference between ICI guide tubes in the reactor coolant system of typical Pressurized Water Reactor. The program, ICITRIC, has been written in FORTRAN language which is available under UNIX environment. Results of this program are compared with those of the commercial code, PATRAN, and both results are almost same Also the results may provide input data for ICI system static and dynamic analysis performed by the commercial code, SUPER PIPE. This program can simulate ICI guide tube routing and locations on support system, and checking the interference between ICI guide tubes. Through a process of iteration, the designer can apply initial conditions, and modify the routing until satisfied with the overall system performance.

• 한국터널지하공간학회 논문집
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• 제20권2호
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• pp.235-253
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• 2018

지하관거 균열로 인한 지하수의 흐름은 주변 지반의 토사유실을 야기하여 관거 인접 지반에서의 공동발생, 나아가 지반함몰(싱크홀) 원인이 된다. 본 연구는 관거의 균열을 모사하는 모형시험을 통해 비점착성 지반에 위치한 지중 비압력 관거의 균열로부터 비롯되는 지반함몰 메커니즘과 이로 인한 파괴모드를 조사하였다. 토사유실 및 함몰 영향인자로서 균열크기, 관거유속, 지하수위, 토피고 그리고 지반구성재료 등을 채택하여 이들 인자들이 함몰거동에 미치는 영향을 조사하였다. 각 인자들에 따른 지반파괴의 형상(파괴모드)과 지반유실량을 분석한 결과, 토피고와 지하수위가 일치하는 경우 최종파괴모드는 침식각이 불연속적으로 변화하는 'Y'형으로 관찰되며, 지하수위가 더 높게 위치하는 경우 침식각이 일정한 파괴면 형상인 'V'형으로 나타난다. 토피고가 증가하는 경우의 파괴형상에서 토피고 영향에 무관한 길이와 토피고에 따라 점진적으로 증가하는 폭을 갖는 수직함몰구간이 형성되는 결과를 얻었다.

• 대한기계학회논문집A
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• 제36권2호
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• pp.137-148
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• 2012

가압경수로의 많은 관통관 중에서 니켈 기저 합금인 Inconel alloy 600 계열의 이종금속용접부는 일차수응력부식균열에 민감하며, 이를 평가하기 위하여 용접부에 작용하는 잔류응력분포를 정확히 예측하는 것이 중요하다. 본 논문에서는 유한요소해석을 이용하여 노즐 맞대기 이종금속용접부에 작용하는 일반적인 잔류응력분포를 예측하였다. 이를 위해 노즐 맞대기 이종금속용접부의 형상을 단순화하여 특정한 형상 변수에 따른 용접부 잔류응력분포를 확인하였으며, 이를 토대로 기존 문헌에 제시된 오스테나이트계 배관 맞대기 용접부 잔류응력 분포식을 수정하여 가압경수로 노즐 맞대기 이종금속용접부에 작용하는 일반적인 잔류응력분포 예측식을 제시하였다.

• 한국압력기기공학회 논문집
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• 제18권1호
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• pp.19-25
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• 2022

Nuclear Power Plants (NPP) should be designed to have sufficient safety margins and to ensure seismic safety against earthquake that may occur during the plant life time. After the 9.12 Gyeongju earthquake accident, the structural integrity of nuclear power plants due to the beyond design basis earthquake is one of key safety issues. Accordingly, it is necessary to conduct structural integrity evaluations for domestic NPPs under beyond design basis earthquake. In this study, the Level 3 LBB (Leak Before Break) evaluation was performed by considering the beyond design basis earthquake for the surge line of a OPR1000 plant of which design basis earthquake was set to be 0.2g. The beyond design basis earthquake corresponding to peak ground acceleration 0.4g at the maximum stress point of the surge line was considered. It was confirmed that the moment behaviors of the hot leg and pressurized surge nozzle were lower than the maximum allowable loading in moment-rotation curve. It was also confirmed that the LBB margin could be secured by comparing the LBB margin through the Level 2 method. It was judged that the margin was secured by reducing the load generated through the compliance of the pipe.

• 한국환경보건학회지
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• 제29권1호
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• pp.8-15
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• 2003

In this study, chlorine dose at water storage tank was predicted to meet the recommended guideline for free chlorine residual in drinking water distribution system, using EPANET which is a computer program that performs extended Period simulation of hydraulic and water quality behavior within pressurized pipe networks. The results may be summarized as follows. The decay of chlorine residual by season varied considerably in the following order; in summer ($25^{\circ}C$) > spring and fall (15$^{\circ}C$) > winter (5$^{\circ}C$). For re-chlorination at water storage tank by season, season-varying chlorine dose was required at its maximum of 1.00 mg/l in summer and minimum of 0.40 mg/l in winter as free chlorine residual. The decay of chlorine residual through out the networks increased with water age spent by a parcel of water in the network except for some points with low water demand. In conclusion, the season-varying chlorine dose as well as the monitoring of water quality parameters at the some points which showed high decay of chlorine residual may be necessary to deliver the safe drinking water.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.89-103
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• 2016

Due to safety of the plant, it became very clear the importance of study occurrence reactor coolant system (RCS) issues specially the primary water stress corrosion cracking (PWSCC). The Systems Engineering (SE) approach is characterized by the application of a structured engineering methodology for the design of a complex system or component. Robotic devices have been used for internal inspection, maintenance and performing remote welding and inspection in high-radiation areas. In this paper, PWSCC overview and inlay and over lay welding methodology introduced, concept of robotic device that can be inserted into the piping via Steam Generator (SG) main way to access to primary piping of pressurized water reactor (PWR) is developed based on SE methodology. A 3D model of the inspection system was developed along with the APR1400 (Advanced Power Reactor)reactor coolant systems (RCS) and internals with virtual 3D simulation of the operation for visualization to prove the validity of the concept.