• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.21-27
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• 2009

This paper presents the numerical study on the strength safety of the prestressed concrete outer tank for a LNG storage tank, which is manufactured by sets of membrane panels with special corrugations. This study for a finite element analysis assumes that the membrane panel of the inner tank was fractured and the liquefied natural gas stored in the inner membrane tank was leaked to the prestressed concrete outer tank. The stress and displacement of the outer tank have been analyzed for five different loadings, which are originated by a hydrostatic pressure and a weight of a LNG, a temperature difference, a weight of the prestressed concrete and a boil-off gas pressure. The computed FEM results indicate that the PC outer tank with a storage capacity of 200,000$m^3$ has a good strength safety for a leaked LNG from the membrane inner tank, but the increased cryogenic loadings in which are originated by a leaked LNG decreases the strength safety of the PC structure. This may lead to the collapse of the outer storage tank.

• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.49-57
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• 2012

From among the NDT (Non-Destructive Testing) methods, the MFL (Magnetic Flux Leakage) PIG (Pipeline Inspection Gauge) is especially suitable for testing pipelines because the pipeline has high magnetic permeability. MFL PIG showed high performance in detecting the metal loss and corrosions. However, MFL PIG is difficult to detect the crack which occured by exterior-interior pressure difference in pipelines and the shape of crack is very long and narrow. Therefore, the new PIG is needed to be researched and developed for detecting the cracks. The CMFL (Circumferential MF) PIG performs magnetic fields circumferentially and can maximize the magnetic flux leakage at the cracks. In this paper, CMFL PIG is designed and the distribution of the magnetic fields is analyzed by using 3 dimensional nonlinear finite element method (FEM). By Simulating and Measuring the magnetic leakage field, it is possible to detect of axial cracks in the pipeline.

• Journal of the Korean Institute of Gas
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• v.17 no.3
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• pp.8-13
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• 2013

The purpose of this paper is to study for fire example by fuel leakage in LPG Vehicle. At first example, the car was repaired the fuel line that was connected with pressure hose between fuel regulator and injector in engine. But the service man was not very tighten with regular torque. At a result, the gas leaked on hot parts of engine. It verified the production of fire by engine heat. At second example, when the repair man, after replacement the injector, inserted the injector in a assembling part of it, he didn't the transform condition of fixing part. Therefore, the tearing phenomenon of O ring producted the controlled leakage of fuel by the injector deflection. It found the fact that the fuel leaked with gap of O ring. At third example. the fuel-cut solenoid valve was lined with pressure regulator unit. But the service man didn't throughly certify the leaked work of connected parts after repaired it. As a result, it certified the fire by engine heating leaked liquefied petroleum gas. Therefore it have to minimize the fire production that the driver should do no problem to throughly manage the fuel system.

• Tribology and Lubricants
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• v.6 no.1
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• pp.89-98
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• 1990

시일의 접촉면이 경사지고, 정현파형이 존재하며 코닝이 있는 경우에 대한 해석을 하였다. 또한 시일링 간극에 존재하는 유체는 비압축성 점성유체이다. 이러한 요소들을 고려한 레이놀즈 방정식의 일반해를 구하기 위하여 멱급수 근사이론을 이용하여 압력분포를 구하였고, 이 결과를 이용하여 시일의 누설 유동량 및 마찰 토오크를 해석하였다. 계산 결과에 의하면 시일 접촉면의 표면파형이나 코닝에 비하여 경사정도가 시일의 성능에 커다란 영향을 주고 있음을 보여주고 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.9-9
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• 1998

다목적 실용위성의 궤도전이 및 위성체 자세제어를 위한 추진시스템의 설계요소에는 구조적 안전성, 우주환경에서의 열제어를 위한 회로 및 구성하드웨어 설계, 연료계통 맥압강하를 위한 장치설계 및 추력기 배기가스 영향을 고려한 형상설계 등이 있으며, 설계검증을 위해 부분해석이 수행된다. 또한 발사환경과 우주 궤도환경에서의 추진시스템 성능평가를 위한 연제어계 기능시험, 압력인증시험, 청정도시험 및 내부/외부 누설시험이 수행된다. 본 논문에서는 추진시스템 설계 및 조립공정에 대해 기술하였고, 시험분석을 통해 시스템의 설계 및 조립공정상의 신뢰성을 검증 분석하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.169-172
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• 1990

본 논문에서는 모달해석을 통해 불안정성을 제거 할 수 있는 메카니즘 (mechanism)으로 만든 씨일(Anti-Swirl Injection type Seal: ASIS)의 등록 성 및 누수량, 압력 강하등을 평씨일, 댐퍼씨일 등과 비교, 해석하여 본질의 역할 및 안정성을 동시에 향상시킬수 있는 씨일을 연구해보고자한다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.2
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• pp.25-33
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• 2016

The thermal stratification phenomenon in the nuclear power plant can cause abnormal deformation of the piping, contact with the support, damage to the support system. Repetition of the thermal stratification phenomenon or variation of the thermal boundary layer can cause thermal fatigue. Thermal stratification phenomenon in nuclear power plants is still an ongoing issue and active research has been carried out. In this paper, the current situation in Korean nuclear power plants is described, followed by the status of research and the future problems on the thermal stratification phenomenon in Korea.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.38-44
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• 2011

The performance experiment was tested for the velocity compound turbine of turbopump which was the main part of 75 ton class liquid rocket engine. The seal is installed between the 1st rotor and the reversing vane to reduce the leakage flow. The turbine outlet pressure of the velocity compound turbine by changing the rotating speed was compared with that of baseline turbine with single rotor including the effect on the total performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.731-740
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• 1995

The objective of this paper is to develop defect assessment technology for integrity evaluation of CANDU pressure tubes. In fracture mechanics analysis, three-dimensional and two-dimensional (line-spring model) finite element analyses were performed to obtain the stress intensity factor for axial and circumferential surface cracks. In leak before break (LBB) analysis, heat transfer analyses for through-wall cracks were performed by considering the cooling effect and the LBB application time was computed. It was shown that the analytical results obtained in this study provide less-conservative but accurate solution for defect assessment of CANDU pressure tubes.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.849-855
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• 2000

This study evaluated the effect of restraint of pressure induced bending(PIB) on crack mouth opening displacement(CMOD) for circumferential through-wall crack in pipe by using both elastic and elastic-plastic finite element analyses. The analyses results showed the restraint of PIB was decreased crack opening for a given crack length and tensile stress, and the effect was considerable for large crack and short restraint length. Also, the restraint effect on CMOD was independent on the variation in pipe diameter and decreased with increasing pipe thickness, and it depended on not total restraint length but short restraint length for non-symmetrically restrained. Additionally, the effect of restraint of PIB was more significant in the elastic-plastic analysis results compared with in the elastic analysis results.