• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.11-27
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• 2003

A fourth order in time and second order in space scheme using a finite-difference method is developed for the non-linear Boussinesq equation. For the solution of the resulting non-linear system a predictor-corrector pair is proposed. The method is analyzed for local truncation error and stability. The results of a number of numerical experiments for both the single and the double-soliton waves are given.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.24-33
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• 1995

The feasibility of generating controlled surface topographies in single-point conventional turning operations is investigated. First a mathematical model of the surface generation process was developed. Second in order to control the texture of the machined surface a micro-positioning stage and the associated command generation software were designed and built. Experimental examples have shown that surface texture can be precisely controlled and is in good agreement with the theoretical predictions.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.7 no.2
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• pp.95-111
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• 2003

BDM mixed methods are obtained for a good approximation of velocity for flow equations. In this paper, we study an implementation issue of solving the algebraic system arising from the BDM mixed finite elements. First we discuss post-processing based on the use of Lagrange multipliers to enforce interelement continuity. Furthermore, we establish an equivalence between given mixed methods and projection finite element methods developed by Chen. Finally, we present the implementation of the first order BDM on rectangular grids and show it is as simple as solving the pressure equation.

• Journal of the Ergonomics Society of Korea
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• v.33 no.3
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• pp.241-253
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• 2014

Objective: The objective of this study was to examine multi-modal interaction effects of input-mode switching on the use of smart phones. Background: Multi-modal is considered as an efficient alternative for input and output of information in mobile environments. However, there are various limitations in current mobile UI (User Interface) system that overlooks the transition between different modes or the usability of a combination of multi modal uses. Method: A pre-survey determined five representative tasks from smart phone tasks by their functions. The first experiment involved the use of a uni-mode for five single tasks; the second experiment involved the use of a multi-mode for three dual tasks. The dependent variables were user preference and task completion time. The independent variable in the first experiment was the type of modes (i.e., Touch, Pen, or Voice) while the variable in the second experiment was the type of tasks (i.e., internet searching, subway map, memo, gallery, and application store). Results: In the first experiment, there was no difference between the uses of pen and touch devices. However, a specific mode type was preferred depending on the functional characteristics of the tasks. In the second experiment, analysis of results showed that user preference depended on the order and combination of modes. Even with the transition of modes, users preferred the use of multi-modes including voice. Conclusion: The order of combination of modes may affect the usability of multi-modes. Therefore, when designing a multi-modal system, the fact that there are frequent transitions between various mobile contents in different modes should be properly considered. Application: It may be utilized as a user-centered design guideline for mobile multi modal UI system.

• International Commerce and Information Review
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• v.11 no.1
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• pp.27-43
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• 2009

This article explored the customers protection regulations in electronic payment system by Article 4A of the UCC and EFTA of 1978 and by Electronic Financial Transaction Act of Korea. Both Korea and America have various regulations to protect concerned parties(customers). For examples, the errors of payment order, money-back guarantee, and unauthorized payment order etc. First, this Article focuses on the allocation of risk of loss caused by ambiguous term in payment orders that do not express the subjective intention of the senders. Second, most rights and obligations created by Article 4A of America can be varied with the agreement of affected parties. But there are some exceptions. The exceptions include the money-back guarantee. So Receiving bank have to pay to originator the ordered money included interest. However, Korea also has money-back guarantee but bank do not pay interest to sender. Lastly, Electronic Funds Transfer Act of 1978 and Regulation E has US$ 50 regulation in order to protect customers on the unauthorized payment order. Article 4A imposes duty to detect unauthorized payment orders to originator in relation to the establishment of commercially reasonable security procedure, while Korean law imposes the duty to notify the bank in order to decrease the loss resulted from unauthorized payment order.

• International Journal of Ocean System Engineering
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• v.2 no.1
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• pp.8-15
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• 2012

An experimental study was carried out in order to understand the kinematics of bichromatic waves. Bichromatic waves are generated in a two-dimensional wave tank, and measured by panorama PIV technique, which allows the flow fields to be captured with respect to a spatial coordinate system. We compared wave profiles and velocities of wave particles obtained by experiment with theoretical results using Stokes 1st and 2nd order waves. The velocity distribution at wave crest and trough of the highest and lowest point of a bichromatic wave are investigated in this study.

• Steel and Composite Structures
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• v.16 no.4
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• pp.389-415
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• 2014

This study deals with dynamic model of composite sandwich panels with functionally graded flexible cores under low velocity impacts of multiple large or small masses using a new improved higher order sandwich panel theory (IHSAPT). In-plane stresses were considered for the functionally graded core and face sheets. The formulation was based on the first order shear deformation theory for the composite face sheets and polynomial description of the displacement fields in the core that was based on the second Frostig's model. Fully dynamic effects of the functionally graded core and face-sheets were considered in this study. Impacts were assumed to occur simultaneously and normally over the top and/or bottom of the face-sheets with arbitrary different masses and initial velocities. The contact forces between the panel and impactors were treated as internal forces of the system. Nonlinear contact stiffness was linearized with a newly presented improved analytical method in this paper. The results were validated by comparing the analytical, numerical and experimental results published in the latest literature.

• Proceedings of the Technology Innovation Conference
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• 2000.06a
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• pp.65-83
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• 2000

In this study, we propose an expert system aided model necessary for extracting the rules, which can diagnose the success level of new product development project. For this purpose, first, we design a classification model to analyze the characteristics of $\ulcorner$parts development projects$\lrcorner$. Second, in order to select success factors, we explore literatures and interview with project managers working at large sized companies of electronic parts. And we conduct the enquete survey and statistical analysis to extract key success factors. Third, in order to decide the level of project success, we use the concept of 'Recearchitivity' as a framework of judgement criteria. Fourth, in order to extract diagnosis rules, we use expert system development tool.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.2
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• pp.137-143
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• 1989

System modeling from input-output data is generally carried out in two steps. The first step is to determine the form of the model. In the second step, the parameters of the model in an appropriate form are estimated from input-output data. This paper presents a method, via single term Walsh functions, for simultaneous estimation of the order and the parameters of linear systems from input-output data. The estimation of the model order is based on minimizing an error function, which is defined by Desai and Fairman. Unknown system parameters are recursively estimated by the least square method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.711-722
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• 2020

An optimization framework using genetic algorithms has been developed towards an automated parametric optimization of the Octabuoy semi-submersible design. Compared with deep draft production units, the design of the shallow draught Octabuoy semi-submersible provides a floating system with improved motion characteristics, being less susceptible to vortex induced motions in loop currents. The relatively large water plane area results in a decreased natural heave period, which locates the floater in the wave period range with more wave energy. Considering this, the hull design of Octabuoy semi-submersible has been optimized to improve the floater's motion performance. The optimization has been conducted with optimized parameters of the pontoon's rectangular cross section area, the cone shaped section's height and diameter. Through numerical evaluations of both the 1st-order and 2nd-order hydrodynamics, the optimization through genetic algorithms has been proven to provide improved hydrodynamic performance, in terms of heave and pitch motions. This work presents a meaningful framework as a reference in the process of floating system's design.