• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.211-215
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• 2004

For design of cryogenic propellant feeding system, one of the main requirements is to meet temperature requirement for satisfying turbo-pump NPSH requirement. In this paper improved method of estimating the thermal stratification in liquid oxygen tank is presented to help design. In the case of liquid rocket using turbo-pump, the inner pressure of liquid oxygen tank is maintained low, so vaporization of liquid oxygen is generally occurred. In this paper, inner process of LOX tank is analyzed by two phase flow modeling. The vaporization rate and required helium mass is investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.238-241
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• 2003

In case of liquid rocket using turbopump, the inner pressure of liquid oxygen tank is maintained low, so vaporization of LOX is generally occurred. This vaporization tendency increases as the inlet helium gas temperature is higher. For estimating the amount of helium in the rocket system, the LOX vaporization phenomena should be carefully considered. In this paper, Inner process of LOX tank is analyzed by two phase flow modeling. the vaporization rate and required Helium mass is investigated with varying inlet helium temperature and heat transfer coefficient.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.3
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• pp.149-157
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• 2017

Since sloshing effects influences ship motions including floater's natural frequencies. The significant factors changing ship motions are inner liquid impact loads and inertia forces and moments with respect to its filling ratio. This means that changing sloshing loads with sloshing effects reduction device (SERD) may control ship motions. In this regard, conceptual model for adjustable SERD was suggested by authors and then implanted into fully coupled program between vessel motion and sloshing. By changing clearances of baffles in the inner tank which were component of SERD, then the roll RAOs from each case were obtained. It is revealed that using well-controlled SERD can maintain natural frequencies of floater even inner tank has different filling ratio.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.3
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• pp.155-164
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• 2019

In this study, the soil-structure interaction(SSI) effect on the seismic response of LNG storage tanks was investigated according to the type of foundation. For this purpose, a typical of LNG storage tank with a diameter of 71m, which is constructed on a 30m thick clay layer over bedrock was selected, and nonlinearity of the soil was taken into account by the equivalent linearization method. Four different types of foundations including shallow foundation, piled raft foundation, and pile foundations(surface and floating types) were considered. In addition, the effect of soil compaction in group piles on seismic response of the tank was investigated. The KIESSI-3D, which is a SSI analysis package in the frequency domain, was used for the SSI analysis. Stresses in the outer tank, and base shear and overturning moment in the inner tank were calculated. From the comparisons, the following conclusions could be made: (1) Conventional fixed base seismic responses of outer tank and inner tank can be much larger than those of considering the SSI effect; (2) The influence of SSI on the dynamic response of the inner tank and the outer tank depends on the foundation types; and (3) Change in the seismic response of the structure by soil compaction in the piled raft foundation is about 10% and its effect is not negligible in the seismic design of the structure.

• 한국가스학회:학술대회논문집
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• 2001.10a
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• pp.122-129
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• 2001

• Journal of the Society of Naval Architects of Korea
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• v.40 no.4
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• pp.46-52
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• 2003

In ship structures, many parts are in contact with inner or outer fluid as stern, ballast and oil tanks. Fatigue damages can be sometimes observed in these tanks which seem to be caused by resonance. Tank structures in ships are in contact with water and the vibration characteristics are strongly affected by the added mass of containing water. Therefore it is important to predict vibration characteristics of tank structures. In order to estimate the vibration characteristics, the fluid-structure interaction problem has to be solved precisely. In the present paper, we have developed a numerical tool of vibration analysis of 3-dimensional tank structures using finite elements for plates and boundary elements for water region. To verify the present analysis, we have made an experiment for vibration characteristics of a tank with elastic opposite panels. And the added mass effect of containing water and the effect of structural constraint between panels are investigated numerically and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.751-759
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• 2003

The theoretical method is developed to investigate the vibration characteristics of the sloshing and bulging mode for the circular cylindrical storage tank with an annular plate on free surface. The cylindrical tank is filled with an inviscid and incompressible liquid. The liquid domain is limited by a rigid cylindrical surface and a rigid flat bottom. As the effect of free surface waves Is taken into account in the analysis, the bulging and sloshing modes are studied. The solution for the velocity potential of liquid movement is assumed as a suitable harmonic function that satisfies Laplace equation and the relevant boundary conditions. The Rayleigh-Ritz method is used to derive the frequency equation of the cylindrical tank. The effect of Inner-to-outer radius ratio and thickness of annular plate and liquid volume on vibration characteristics of storage tank is studied. The finite element analysis is performed to demonstrate the validity of present theoretical method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.325-330
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• 2012

This paper describes the structural analysis and optimization of stiffeners used in inner tanks for liquid natural gas (LNG) storage, so that the costs can be minimized while the critical buckling load of the inner tank still exceeds the external pressure exerted by the perlite. The original calculation of perlite pressure applied to the inner tank was based on Zick's code, which led to the overestimation of the external pressure, and consequently, an oversized stiffener. In this study, the effects of the material properties of perlite on the external pressure distribution are scrutinized, and the optimum dimensions of a single stiffener are finally obtained through a series of parametric studies. A 15% decrease in the cost of the stiffener compared with the original design is achieved.

• Journal of ILASS-Korea
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• v.1 no.4
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• pp.46-53
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• 1996

The present study is aiming at improving the performance of main nozzle of an air jet loom with a modified reed and auxiliary nozzles. The double coaxial pipe jets consisting of a central air jet and an annular air jet have been experimentally investigated. The duter jet has a potential core and a constant velocity. The inner jet through an inner long pipe is induced by the subatmospheric pressure near the inner nozzle edge, and the jet velocity of an inner pipe is always lower than that of a outer pipe. The static pressures of the main nozzle over a wide range of the nozzle tank pressure were measured, and the nozzle velocity and Mach numbers were analytically calculated. Experiment81 results indicate that the critical condition of Mach number of unity to occur at the two positions in a main nozzle; one of them is the needle tip and the other is the acceleration tube exit An increase in the tank pressure causes the critical throat condition to occur at the two positions above. The velocity of acceleration-tube exit is maximum at the critical length L* and flow patter in acceleration-tube over critical lengh remains unstable.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.69-72
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• 2014

If LNG is leaked from 9% Ni steel inner tank by damage, LNG is retained by outer concrete tank. Then large tensile stress can be caused at cylindrical bottom of outer tank by temperature difference between outer and inner surface of outer tank. Therefore, in order to reduce the tensile stress is caused by temperature difference, corner-protection is installed with insulation and 9% Ni steel as a second barrier. In this paper, using finite element method, structural analysis was performed for rectangular and circular shape of knuckle and based on the results, fatigue life of welds of corner protection was predicted. As a consequence of structural analysis, safety factor of circular knuckle shows 33% bigger than rectangular one shows, and circular knuckle has 25% bigger fatigue life time than rectangle has. These results can be applied to life time assessment and design optimization in the future.