• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.166-173
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• 2007

Collision analysis problems between ship to ship can be generally classified into the external mechanics(outer dynamics) and internal mechanics(inner dynamics). The former can be also dealt with the concept of fluid-structure interaction and the use of rigid body dynamic program, depending on the ways handling the hydrodynamic pressure due to surrounding water. In this study, full scale ship collision simulation was carried out, such as a DWT 75,000 ton striking ship collided at right angle to the middle of a DWT 150,000 struck ship with 10 knots velocity, coupling MCOL, a rigid body mechanics program for modeling the dynamics of ships, to hydrocode LS-DYNA. It could be confirmed that more suitable damage estimation would be performed in the case of the collision simulations with consideration of surrounding water through the comparison with the collision simulation results of fixed struck ships without it. Through this study, the opportunity could be obtained to establish a more effective ship collision simulation technique between ship to ship.

• Journal of the Korea Convergence Society
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• v.9 no.8
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• pp.17-24
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• 2018

Design patterns can be classified as software reuse technique that might provide effective solutions to specific problems that occur repeatedly in software development. In particular, object-oriented design patterns are incorporated into various software platforms and frameworks to increase software productivity. This paper aims to support general guidelines relating to design patterns for Android-based game programming. The proper use of the design pattern could be effective in not only for software development productivity, but also for post-development software maintenance. This paper provides fundamental procedures and case studies for applying design patterns to game programming on the Android platform. Typical object-oriented design patterns such as MVP, Singleton, Observer, and State have been applied to the development of Android game programs.

• Journal of Ocean Engineering and Technology
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• v.20 no.1 s.68
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• pp.69-76
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• 2006

The design of efficient search path to maximize the Cumulative Detection Probability(CDP) is mainly dependent on experience and intuition when searcher detect the target using SONAR in the ocean. Recently with the advance of modeling and simulation method, it has been possible to access the optimization problems more systematically. In this paper, a method for the optimal search path calculation is developed based on the combination of the genetic algorithm and the calculation algorithm for detection range. We consider the discrete system for search path, space, and time, and use the movement direction of the SONAR for the gene of the genetic algorithm. The developed algorithm, OASPP(Optimal Acoustic Search Path Planning), is shown to be effective, via a simulation, finding the optimal search path for the case when the intuitive solution exists. Also, OASPP is compared with other algorithms for the measure of efficiency to maximize CDP.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.60-67
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• 2004

With the proliferation of nonlinear loads, high neutral harmonic currents in three-phase four-wire distribution system have been observed It has been also known that the ground impedance has an effect on the neutral currents of a system which operates with harmonics present. On-site measurements of harmonic currents and voltages, and the soil resistivity and ground resistance under case study system were made and the corresponding equivalent circuit for the harmonics analysis was developed This equivalent circuit model was simulated numerically and graphically through the use of MATLAB and CDEGS software packages, and adequate results were obtained.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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• pp.137-143
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• 2015

This paper presents the intra capacitance modeling based on the winding method and section bobbin for CM choke capable of EMI attenuation of broad bands from lower to higher frequency bands and high frequency type common-mode choke capable of EMI attenuation of high frequency band used in the EMI Block of LED-TV SMPS. The case of high frequency type CM choke can be explained by the parasitic capacitance of three types of CM choke. The winding method of section bobbin type is smaller than the others. The first resonant frequency of the proposed CM choke tends to increase as the parasitic capacitance becomes small and its impedance characteristics improved performance as the first resonant frequency increases. The CM chokes of the proposed section bobbin type shows that in the future, the method may have practical use in LED/LCD-TV SMPS and in several applications, such as LED lighting, adapters, and so on.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.672-677
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• 2007

Recently, the new finite element method which uses NURBS as shape functions was proposed. It is very promising because it can directly use CAD data to describe geometry and discretize problem domain. In this case, CAE models are not approximated but represent exact geometry. So, it can contribute to more accurate results. In addition, it can greatly reduce CAE costs in that simulation models don't have to be made up independently. But in spite of these advantages, the method using NURBS have also some disadvantages. NURBS surface cannot be refined locally. T-splines are recently developed surface modeling technique. A T-spline surface is a NURBS surface with T-junctions and is defined by a control grid called T-mesh. The T-junctions enable T-spline surfaces to be refined locally. That is, it is possible to add a single control point to a T-spline control grid without propagating an entire row or column of control points and without altering the surface. In this research, the finite element analysis using T-splines is studied. In this analysis, CAD data are used directly for engineering analysis. Some problems with complex geometry are solved. And the results will be compared with ones of conventional FEM.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.199-202
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• 1996

Although numerous studies demonstrate that one technique outperforms the others for a given data set, there is often no way to tell a priori which of these techniques will be most effective to solve a specific problem. Alternatively, it has been suggested that a better approach to classification problem might be to integrate several different forecasting techniques by combining their results. The issues of interest are how to integrate different modeling techniques to increase the prediction performance. This paper proposes the post-model integration method, which means integration is performed after individual techniques produce their own outputs, by finding the best combination of the results of each method. To get the optimal or near optimal combination of different prediction techniques. Genetic Algorithms (GAs) are applied, which are particularly suitable for multi-parameter optimization problems with an objective function subject to numerous hard and soft constraints. This study applied three individual classification techniques (Discriminant analysis, Logit and Neural Networks) as base models to the corporate failure prediction context. Results of composite prediction were compared to the individual models. Preliminary results suggests that the use of integrated methods will offer improved performance in business classification problems.

• Journal of Distribution Science
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• v.17 no.6
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• pp.43-56
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• 2019

Purpose - With the increasing number of small business owners who reports the cessation of their businesses, the rate of closing the business within the year is increasing as well. The efforts have been made continuously to revitalize the business through the inflow of government or private capital. Maintaining the fast-changing commercial districts with the existing support is difficult, so it is urgent state that needs for commercial district reorganization. The differentiate aspect is that this new measures for small-block-unit commercial modeling can be introduced to promote these aging/deposit private-owned shops politically. Research design, data, and methodology - This study is to develop a sustainable theme shopping rehabilitation method which considers the characteristics of local cities based on the case studies of developed countries' commercial areas to revitalize the central urban areas of local cities. Results - The purpose of this study as stated above is to manage the local commercial area through the program that purchases the empty stores, and the measure to secure the autonomy among stores. Conclusions - The government should concentrate on projects such as vacant store purchase programs, which are omitted from past achievements, and maximize the effect of the project through inter-departmental project packages.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.2
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• pp.159-171
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• 2012

Aerosol direct radiative forcing (ADRF) retrieval method was developed by combining data from passive and active satellite sensors. Aerosol optical thickness (AOT) retrieved form the Moderate Resolution Imaging Spectroradiometer (MODIS) as a passive visible sensor and aerosol vertical profile from to the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) as an active laser sensor were investigated an application possibility. Especially, space-born Light Detection and Ranging (Lidar) observation provides a specific knowledge of the optical properties of atmospheric aerosols with spatial, temporal, vertical, and spectral resolutions. On the basis of extensive radiative transfer modeling, it is demonstrated that the use of the aerosol vertical profiles is sensitive to the estimation of ADRF. Throughout the investigation of relationship between aerosol height and ADRF, mean change rates of ADRF per increasing of 1 km aerosol height are smaller at surface than top-of-atmosphere (TOA). As a case study, satellite data for the Asian dust day of March 31, 2007 were used to estimate ADRF. Resulting ADRF values were compared with those retrieved independently from MODIS only data. The absolute difference values are 1.27% at surface level and 4.73% at top of atmosphere (TOA).

• Korean Journal of Computational Design and Engineering
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• v.11 no.3
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• pp.183-196
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• 2006

A new operation strategy. which can guarantee the data consistency of engineering information among the various intelligent information systems, is presented for engineering information of bridges, and construction methodology of integrated database is developed to support the strategy. The two core standard techniques are adopted to construct the integrated database. One is the Standard for the Exchange of Product Model Data (STEP) for CAD/CAE information and the other is the Extensible Markup Language(XML) for engineering document information. The former enabler structural engineers to handle the structural details with three-dimensional geometry-based information of bridges, and ACIS solid modeling kernel is employed to develop AutoCAD based application modules. The latter can make document files into data type for web-based application modules which assist end-users to search and retrieve engineering document data. In addition, relaying algorithm is developed to integrate the two different information, e.g. CAD/CAE information and engineering document information. The pilot application modules are also developed, and a case study subjected to the Han-Nam bridge is presented at the end of the paper to illustrate the use of the developed application modules.