• KDI Journal of Economic Policy
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• 제38권2호
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• pp.45-62
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• 2016

This paper analyzes changes in the export potential and competitiveness of China, Japan, and Korea. The analysis of Japan's export market share reveals that in sectors where Korea's potential was strong in the early 1990s, Japan's market share diminished. This suggests the possibility that Korea was catching up with Japan, eating into Japan's market share. The same analysis of Korea's export market share in the 2000s shows, for items in which China's export potential was high, Korea's market share has declined comparatively since 2010, with the tendency growing much larger. China's export potential continues to expand in markets for Korea's key export products, making it difficult to rule out the possibility that Korea's competitiveness in key export products will be hindered, driven by the catching up of China. To respond to these challenges, it is important for Korea continuously to foster and enhance creative and core capabilities that latecomers will not easily be able to emulate.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.107-125
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• 2013

A strain smoothing meshfree formulation with stabilized conforming nodal integration is presented for modeling the consolidation process in saturated porous media. In the present method, nodal strain smoothing is consistently introduced into the meshfree approximation of strain and pore pressure gradient variables associated with the saturated porous media. Meanwhile, in order to achieve a consistent numerical implementation, a smoothing approximation of the meshfree shape function within a nodal representative domain is also proposed in the stiffness construction. The resulting discrete system of equations is all expressed in smoothed nodal measures that are very efficient for numerical evaluation. Subsequently the space-time fully discrete equations are further established by the generalized trapezoidal rule for time integration. The effectiveness of the proposed meshfree consolidation analysis method is systematically illustrated by several benchmark problems.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.238-242
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• 2001

In this paper, we proposed an optimal identification method of the membership functions and the numbers of fuzzy rule base for the stabilization controller of the Thermal process control system by RVEGA. Although fuzzy logic controllers and expert systems have been successfully applied in many complex industrial process, they must rely on experts knowledges. So it is difficult in determination of the linguistic state space, definition of the membership functions of each linguistic term and the derivation of the control rules. To verify the validity of this RVEGA-based fuzzy controller, Thermal process control system, with strong nonlinear dynamics, was selected for application of this algorithm and compare with PI controller, and the empirically improved fuzzy controller.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.202-215
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• 2013

This paper proposes a SEPIC-input, self-driven, active clamp ZVS converter, where an auxiliary winding and a RC delay circuit are employed to drive the active clamp switch and to achieve asymmetrical duty control without any other extra circuits. Based on the fixed dead time and the resonance between capacitors and inductors, both the main switch and the auxiliary switch can rule the ZVS operation. Detailed operation modes are presented to illustrate the self-driven and ZVS principles. Furthermore, an accurate state-space model and the transfer functions of the proposed converter have been presented and analyzed in order to optimize dynamic performance. The model provides efficient prediction of converter operations. Experimental results, based on a prototype with 80V input and 15V/20A output, are discussed to verify the transient and steady performance of the proposed converter.

• 디지털콘텐츠학회 논문지
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• 제15권1호
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• pp.39-43
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• 2014

본 논문은 홈 네트워크 기반에서 멀티미디어 공동 작업 공간을 위한 화이트보드에 대해서 제안하였다. 본 시스템은 공동 작업에 참여한 사용자들이 다른 참여자들에게 같은 뷰로써 공유된 미디어들을 참조할 수 있도록 구축한다. 본 논문에서는 화이트보드를 통하여 미디어 데이터의 신뢰성을 향상시키는 방법에 대해서 기술한다. 본 논문은 규칙-기반 DEVS(Discrete Event System Specification) 모델링과 시뮬레이션 기법을 사용하면서 분산 멀티미디어 상에서 화이트보드를 이용한 미디어 데이터 시스템의 성능 분석을 설명한다.

• 대한조선학회논문집
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• 제45권2호
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• pp.213-220
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• 2008

The aim of this paper is to build up the design model using ASMOD(Adaptive Spline Modeling of Observation Data) for the optimum scale of fleet, ship particulars and ship speed, etc. ASMOD, which define membership functions of fuzzy rule as B-spline basis function, represents a whole system as the sum of the sub-model. As it reduces the number of division of the space generated by the fuzzy set of input variables, it has a advantage of simplification to model structure and is efficient to represent the non-linear model.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1195-1198
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• 1993

We investigate a systematic design procedure of automated rule generation of fuzzy logic based controller for uncertain dynamic systems such as an engine dynamic model.“Automated Tuning”means autonomous clustering or collection of such meaningful transitional relations in the state-space. Optimal control strategies are included in the design procedures, such as minimum squared error, minimum time, minimum energy or combined performance criteria. Fuzzy feedback control systems designed by the cell-state transition method have the properties of closed-loop stability, robustness under parameter variabtions, and a certain degree of optimality. Most of all, the main advantage of the proposed approach is that reliability can be potentially increased even if a large grain of uncertainty is involved within the control system under consideration. A numerical example is shown in which we apply our strategic fuzzy controller design to a highly nonlinear model of engine idle speed contr l.

• 대한산업공학회지
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• 제15권1호
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• pp.1-15
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• 1989

In the past few years, increasing numbers of automatic storage/retrieval system (AS/RS) using computer controlled storage/retrieval machine have been installed. This paper introduces two modeling approaches to determine the best operating policy for AS/RS : an M/G/1 queueing model and a computer simulation model. The operating policy consists of three elements. : the operation command cycle, the storage location method, and the operation dispatching rule. The analysis based on M/G/1 model is suitable for a quick and approximate evaluation, due to its inherent strict assumptions. The computer simulation can be used to perform a more realistic analysis. It is shown through the study that a significant improvement in the throughput and/or the space requirement can be expected by determining the best operating policy to a particular system. Most important, the computer simulation demonstrates its powerful capability in evaluating dynamic stochatic systems with imperfect information.

• 산업공학
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• 제12권2호
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• pp.210-221
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• 1999

Several researchers have previously studied the problem of allocating buffer storage to maximize the throughput rate and/or minimize the mean buffer average of a transfer line for a given total amount of buffer space. But there seems to be very little difference in performance between intuitively reasonable and optimal allocations. This paper proposes and illustrates a methodology, based on the robust design concept of Taguchi, to allocate buffer storage of long transfer lines with a given total amount of buffer capacity when up and down times follow exponential distributions, respectively. We show how this procedure using simple heuristic rule can be used for design of long transfer lines.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.87-94
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• 2003

배전계통에서의 사고 발생시 정전으로 인한 수용가의 손실을 최소로 하기 위하여 정전구역에 대한 신속한 복구가 이루어져야 한다. 본 논문에서는 배전계통의 정전복구를 위한 전문가 시스템을 제안하였다. 제안된 전문가 시스템은 복구과정에서 전문가의 경험적 규칙을 이용함으로써 복구에 소요되는 스위칭 횟수를 최소화 하도록 하였다. 복구 과정은 일반적인 위상구조 지식 기반의 응용을 통해 전문가 시스템의 상태공간에서 타당한 경로를 찾는 문제로 표현하였다. 또한, 다양한 배전계통 구조를 고려하기 위해 다중 부하절체 기법을 제안하였다.