• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.1
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• pp.37-48
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• 1995

The TIDE, nonlinear finite element model for the simulation of tidal analysis in a shal- low ooastal area was tested for its applicability at the Saemankeum day. Calibration of the TIDE model has been carried out using the six observed field data collected at five locations within the region for tidal velocity. Verification tests have been done using the six observed field data and four data o- tained from the hydraulic model test for the tidal velocity and elevation. Since the simula- tion results for the tidal elevation at Kunsan outer port by the TIDE model are well agreed with the results from the tidal table for one month, it is proved that the TIDE model may be used effectively to predict the tidal movement in the Saemankeum bay for a longer period.

• The Korean Journal of Applied Statistics
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• v.22 no.5
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• pp.1007-1017
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• 2009

Forecasting for air demand such as passengers and freight has been one of the main interests for air industries. This research has mainly focus on the comparison the performance between the univariate seasonal ARIMA models and the multivariate time series models. In this paper, we used real data to predict demand on international passenger and freight. And multivariate time series models are better than the univariate models based on the accuracy criteria.

• Smart Media Journal
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• v.1 no.4
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• pp.35-43
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• 2012

In this paper, we consider the current status of smart TV and propose a business model established on the smart TV ecosystem. There are two views on the outlook of the smart TV market, one of which takes optimistic prospect and the other one is pessimistic. However, mostly it is believed that the innovation will continue in smart TV technology and the market will expand. In this paper, we proposes a two-way, active and consumer oriented business model for smart TV using subtitle information. Finally, we expect to contributing to reduce the gap of information between countries to spread the Han-Wave.

• Information Systems Review
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• v.24 no.1
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• pp.105-123
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• 2022

Thanks to the remarkable success of Artificial Intelligence (A.I.) techniques, a new possibility for its application on the real-world problem has begun. One of the prominent applications is the bankruptcy prediction model as it is often used as a basic knowledge base for credit scoring models in the financial industry. As a result, there has been extensive research on how to improve the prediction accuracy of the model. However, despite its impressive performance, it is difficult to implement machine learning (ML)-based models due to its intrinsic trait of obscurity, especially when the field requires or values an explanation about the result obtained by the model. The financial domain is one of the areas where explanation matters to stakeholders such as domain experts and customers. In this paper, we propose a novel approach to incorporate financial domain knowledge into local rule generation to provide explanations for the bankruptcy prediction model at instance level. The result shows the proposed method successfully selects and classifies the extracted rules based on the feasibility and information they convey to the users.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.3
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• pp.146-155
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• 1992

It has been conventional to treat the land boundary as a fixed one in numerical modeling of tidal flows, particularly in the finite element scheme. However conventional models using the fixed land boundary result in unrealistic tidal flows in inter-tidal zones which exist over wide coastal area in Korea. In this study, a 2-dimensional hydrodynamic model, using finite element method for moving boundary problems was developed. The performance of the model was tested in a rectangular channel with an open boundary at one end and a moving boundary at the other end. The model was applied to calculate the tidal currents in Maro Hae, located in the southwestern part of Korea where wide tidal flats develop. The behavior of tidal currents in the Udolmok and near the tidal flats in the study area was satisfactory when compared with the observed data. Variation of tidal currents due to the construction of Kochunam sea-dyke which barrages large area of tidal flat was presented. The results of this study confirm the efficiency of moving boundary treatment in coastal numerical models.

• Tunnel and Underground Space
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• v.22 no.1
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• pp.22-31
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• 2012

In this study, scaled model tests were performed to investigate the stability of an asymmetrical twin tunnels constructed in rock mass comprising alternating layers of sandstone and shale. Each of tunnels had a differently shaped section, where the one was already constructed tunnel including lining structure but the other was planned to be under construction. Four types of test models which had respectively different pillar widths and loading conditions were experimented, where both crack initiating pressures and deformation behaviors around tunnels were investigated. The cracks of pillar mainly began to appear at the interfaces of alternating layers, following additional shear displacement between layers was confirmed as one of the most important factors of pillar failure in case of the model of pillar width 0.5D. The models with shallower pillar widths proved to be unstable because of lower crack initiating pressures and more tunnel convergences than the models with thicker pillar widths. The failure and deformation behaviors of tunnels were also dependent on the loading conditions, where the model of coefficient of lateral pressure 1.0 was more stable than the other model. Futhermore, the results of FLAC analysis were qualitatively coincident with the experimental results.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.143-154
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• 1997

A numerical model for solving advection-diffusion equation is presented by splitoperator method combining the Holly-Preissmann scheme with a fifth-degree interpolating polynomial for advection operator and the explicit scheme porposed by Hobson et al. for diffusion operator. To examine the developed model, the obtained numerical solutions are compared with both the analytic solution and those from the existing models for the instantaneous source (Gaussian hill) and the continuous source (advanced front) at upstream boundary with constant velocity and diffusivity condition. For the various cases having different Courant and Peclet numbers, it is shown that the present study provides stable solutions even for Courant numbers exceeding one. The result obtained by the present study also agree well with existing analytical solutions for both cases. The proposed explicit scheme somewhat releases the conventional restriction of explicit schemes for determining the time step size and provides satisfactory results for relatively large time step size.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1181-1190
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• 2010

When an insurer develops an insurance product, it is very critical to determine reasonable premiums, which is directly related to insurer's profits. There are three methods to determine premiums. Frist, the insurer utilizes premiums paid to the similar cases to the current one. Second, the insurer calculates premiums based on policyholder's past records. The last method is to combine the first with the second one. Based on the three methods, there are two major theories determining premiums, Limited Fluctuation Credibility Theory not based on statistical models and Greatest Accuracy Credibility Theory based on statistical models. There are well-known methods derived from Greatest Accuracy Credibility Theory, such as, Buhlmann model and Buhlmann-Straub model. In this paper, we extend the Buhlmann-Straub model to accommodate the fact that variability grows according to the number of data in practice and suggest a new non-parametric method to estimate the premiums. The suggested estimation method is also applied to the data gained from simulation and compared with the existing estimation method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.3
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• pp.205-215
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• 1994

A 3-dimensional numerical model of wind-induced flows has been established. and comparative evaluation of determination methods of vertical eddy viscosity has been performed. The model uses turbulence models to calculate vertical eddy viscosity. The examined methods arp 0-equation model of functional form, 1-equation model of turbulence kinetic energy, and two 2-equation models ($textsc{k}$-$\varepsilon$ and $textsc{k}$-ι models). The evaluation includes the verification tests against experimental data for wind-driven current On a closed one-dimensional channel and a recirculating one-dimensional channel. Comparative study of turbulence models has shown that the proper distribution of turbulence scale is parabolic and the eddy viscosity is depending strongly on mixing depth due to wind.

• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.67-74
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• 2011

This study deals with the traffic accidents data from the Korean rotaries (circular intersections) to verify their characteristics affected by different vehicle types. This paper categorized the data into three groups based on vehicle types, and developed a set of accident models. The paper proposed two ZIP models and one negative binomial model through a statistical analysis for three vehicle types: automobile, truck and van, and others. The differences among those models were then statistically compared.