• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1995.06a
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• pp.299-303
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• 1995

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.89-90
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• 1997

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.69-81
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• 2001

The constitutive relation among capillary pressure, saturation and relative permeability should be predetermined in order to simulate immiscible water-gas flow in porous media. The relation between saturation and relative permeability becomes more important when the capillary force can be disregarded and viscous friction force governs the flow. In this study, a 2-dimensional finite difference numerical model was developed, in which the variation of viscosity with pressure and that of relative permeability with water saturation can be treated. Seven cases of parallel plate tests were performed in order to obtain the characteristic equation of relative permeability which would be used in. the developed numerical model. It was not possible, however, to match the curves of relative permeability from the plate tests with the existing emperical models. Consequently a logistic equation was proposed as a new emperical model. As this model was composed of the parameter involving aperture size, any aperture size of fracture can be applied to the model. For the purpose of verification, the characteristic equation of relative permeability was applied to the developed numerical model and the computed results were compared with those of plate test. As a result of application of numerical model, in order to check the field applicability, to single fracture surrounding an underground storage cavern, the simultaneous flow of water and propane gas was able to be simulated properly by the model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.2
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• pp.148-156
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• 2008

WAM(WAve Model), deep water wave model has been extended to the region of shallow water, incorporating wave breaking, and triad wave interaction. To verify this model, two numerical simulations for hydraulic experiments of Chawla et al.(1998) and Beji and Battjes(1993) are performed. The computed results show good agreements with measured ones. To identify its applicability to real sea, it is applied to storm wave modelling for typhoon Maemi. Numerical results compared with measured ones at Geoje, Busan and Ulsan show reasonable wave height estimations.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.175-183
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• 2010

In this study, laboratory experiments are conducted to investigate flow-fields around floating breakwaters by using the LDV(Laser Doppler Velocimetry) system. The LDV system is a well-known equipment to measure fluid particle velocities in laboratory experiments. Although the system requires great efforts and enormous time for measurements, it can provide precise velocity fields comparing to other available equipments. Various types of drafts and shapes for breakwaters are employed in laboratory experiments to analyze a relation between flow-fields and vorticity. A series of numerical experiments are also carried out by using a two-dimensional Navier-Stokes equations model. Numerically predicted results are compared with laboratory measurements.

• Convergence Security Journal
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• v.7 no.1
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• pp.45-53
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• 2007

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, Goel-Okumoto and Yamada-Ohba-Osaki model was reviewed, proposes the hyper-exponential distribution reliability model, which maked out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method. For model determination and selection, explored goodness of fit (the error sum of squares). The methodology developed in this paper is exemplified with a software reliability random data set introduced by of Weibull distribution (shape 0.1 & scale 1) of Minitab (version 14) statistical package.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.59-65
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• 2005

In this paper a constitutive model for large cracks in concrete and other brittle materials subject to dynamic and cyclic leading is presented. The suggested model is based on the plastic-damage model for cyclic leading. A numerical formulation based on the three-step return-mapping algorithm for the proposed large crack model is also present. The numerical examples show that the present algorithm works appropriately under dynamic leading and should be used in large crack problems to prevent excessive tensive plastic strain development causing unrealistic results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.205-212
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• 2007

Parabolic approximation wave models based on $Pad{\acute{e}}$ approximants are analyzed in order to calculate wave transformation. In this study a $Pad{\acute{e}}(2,2)$ parabolic approximation model is developed to increase the accuracy of computation in comparison with the existing models. Numerical studies on a constant sloping bed show that the new model proves to allow for much more successful treatment of large angles of incidence than is possible using the previously available models.

• Convergence Security Journal
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• v.7 no.2
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• pp.1-8
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• 2007

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault (intensity function). In this paper, intensity function of Goel-Okumoto model was reviewed, proposes Kappa (2) and the Burr distribution, which maked out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method. For model determination and selection, explored goodness of fit (the error sum of squares) The methodology developed in this paper is exemplified with a software reliability real data set introduced by NTDS (Naval Tactical Data System)

• Convergence Security Journal
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• v.8 no.4
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• pp.115-120
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• 2008

Accurate predictions of software release times, and estimation of the reliability and availability of a software product require quantification of a critical element of the software testing process： Change-point problem. In this paper, exponential (Goel-Okumoto) model was reviewed, proposes the percentile change-point problem, which maked out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE statistics, for the sake of efficient model, was employed. Using NTDS data, The numerical example of percentilechange-point problemi s presented.