• Annual Conference of KIPS
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• 2002.04a
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• pp.607-610
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• 2002

최근 5년간 e-Loaming에 대한 중요성과 웹 기반 학습의 활용성은 대부분의 기업에서 LMS(Learning Management System)의 형태로 도입을 하고 있다. 또한, 현재는 학습관리와 컨텐츠의 관리영역을 통합하고 학습 컨텐츠의 객체화를 통한 재사용성과 관리 측면을 극대화하는 노력이 이루어지고 있다. e-Learning을 활용하는 80%이상의 기업이 표준적인 메타데이터와 리파지토리를 기반으로하는 LCMS(Leaning Content Management System)형태로 전환하는 시점에서 LCMS 관린 연구가 요구된다. 본 연구에서는 학습객체를 통한 코스의 개발과 관리 배포를 위한 LCMS를 재사용 가능한 실행 모듈인 컴포넌트 기반으로 구성하고자 한다. 학습 컨텐츠 관리시스템에서의 주요 기능을 계층적으로 체계화하며, LCMS를 위한 컴포넌트 참조 아키텍처를 정의함으로써 개발의 용이성과 시간, 비용의 효율성을 보장한다. 또한, 재사용 및 공유가능한 학습객체를 통한 코스 개발로 학습 컨텐츠의 중복을 피하고 학습과정 개발의 시간 효율성을 기대한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.210-216
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• 1999

Todays computer communication technology let people to do many unrealistic things possible and the use of those technologies is becoming increasingly prevalent throughout the military operation. Both DIS and ADS are welled defined computer aided military simulations. This study discusses a simulation of stochastic combat network modeling through Internet. We have developed two separate simulation models, one for clients and another for server, and validated for conducting studies with these two models. The object-oriented design was necessary to define the system entities and their relationship, to partition functionality into system entities, and to transform functional metrics into realizations derived from system component behaviors. Heterogeneous forces for each side are assumed at any battle node. The time trajectories for mean number of survivors at each node, some important combat measures, and relative difference computations between models were made. We observe and may conclude that the differences exist and some fo these are significant based on a limited number of experiments.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.187-190
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• 1998

The values of physical components of the plants and controllers as well as the relevant environmental conditions change in time, thus the output performance can be deteriorated during the operating span of the system. Naturally the duty of calibration or the prevention of performance deterioration due to excessive component sensitivity should be provided to the control system. The proposed controller, whenever necessary, measures the open-loop and close-loop characteristics, and then calculates the offset and sensor gain correction values based on the prepared standard measurements It is applied to the control of a flexible link system with the gain and offset calibration problems in the light sensor module for position to show the applicability. In this paper, we propose a digital controller which has the capability of calibration gain and offset adjustment using fuzzy methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.240-247
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• 2008

In this paper, we propose a digitally implementable synchronization method for the UWB system. This is achieved by manipulating the frequency components of a synchronizing signal which is the sequence of pulses of periodicity. We analyze the dependancy of the number of pulses and pulse interval on the intrinsic synchronization accuracy. Moreover, through the computer simulation, the performance of the proposed method is examined via varying system parameters.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1746-1752
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• 2014

This paper presents an application of proportional-resonant (PR) current controllers in modular multilevel converter-high voltage direct current (MMC-HVDC) system under unbalanced voltage conditions. The ac currents are transformed and controlled in the stationary reference frame (${\alpha}{\beta}$-frame). Thus, the complex analysis of the positive and negative sequence components in the synchronous rotating reference frame (dq-frame) is not necessary. With this control method, the ac currents are kept balanced and the dc-link voltage is constant under the unbalanced voltage fault conditions. The simulation results based on a detailed PSCAD/EMTDC model confirm the effectiveness of the proposed control method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.754-755
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• 2017

CPS refers to a computer-based component and system that closely connects various complicated processes and information of real space with the cyber space that provides data access and processing services through internet. In this paper, CPS was applied to shop-floor as a part of CPS research.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1004-1013
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• 2017

This paper presents an interleaving scheme for parallel-connected power systems to reduce the DC-link current ripple. A paralleled generator system generates current ripple by the Pulse Width Modulation (PWM) of each generator side converter. The current ripple in the DC-link degrades the efficiency of the whole generator system and decreases the lifetime of the DC-link capacitors. To mitigate these issues, the expression of the DC-link current is derived by a double-integral Fourier analysis while considering the modulation schemes. Optimized interleaving angles for the parallel generator system are obtained based on an analysis to minimize the dominant current harmonics component. Finally, the proposed interleaving scheme reduces the RMS value of the DC-link current ripple. Simulation and experimental results verify the effectiveness of the proposed interleaving scheme.

• Smart Structures and Systems
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• v.22 no.6
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• pp.711-725
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• 2018

Most of the practical engineering structures exhibit nonlinearity due to nonlinear dynamic characteristics of structural joints, nonlinear boundary conditions and nonlinear material properties. Hence, it is highly desirable to detect and characterize the nonlinearity present in the system in order to assess the true behaviour of the structural system. Further, these identified nonlinear features can be effectively used for damage diagnosis during structural health monitoring. In this paper, we focus on the detection of the nonlinearity present in the system by confining our discussion to only a few selective time-frequency analysis and multivariate analysis based techniques. Both damage induced nonlinearity and inherent structural nonlinearity in healthy systems are considered. The strengths and weakness of various techniques for nonlinear detection are investigated through numerically simulated two different classes of nonlinear problems. These numerical results are complemented with the experimental data to demonstrate its suitability to the practical problems.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.2
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• pp.61-68
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• 2021

A decrease in the fertility rate leads to a reduction of troops, so the need to efficiently operate the troops is growing. Therefore, it is necessary to develop a system for estimating warship manpower. In this study, system development was performed according to the CBD methodology. The user requirements were defined and the system function that satisfies the requirements was derived. And through the development process, the CBD methodology and the systems engineering process were compared. As a result, similarities were confirmed in the analysis and concept design stages, so the possibility of merging the two processes was suggested.

• Journal of Drive and Control
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• v.20 no.1
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• pp.27-33
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• 2023

From the perspective of dental chair manufacturers, it is important to of localizing hydraulic system in order to secure market competitiveness. This study aims to develop the analysis model of a dental chair which overseas companies secure core technologies. The study follows the steps below. First, the component parts of the solenoid valve unit of a foreign leading company are analyzed and implemented in virtual environment. Second, dynamic behavior scenario is established based on solenoid valve signal chart provided by a foreign leading company. The analysis model is verified and its performance is analyzed using dynamic behavior according to each scenario. Third, a simulation is carried out to determine whether the cylinder velocity of designed hydraulic system surpasses 1cm/s as required by the design.