• 유공압시스템학회논문집
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• 제4권2호
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• pp.28-33
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• 2007

In the power plant facility which use soft coal as a power source the fan pitch blade control hydraulic actuator is used to control the inlet and outlet gas to regulate the internal pressure of the furnace and control the frequence. Sometimes malfunctions of this equipment lead to the decline of boiler thermal efficiency and unexpected power plant trip. In order to localize the fan pitch blade control hydraulic actuator specially for the 500MW large scale boiler, Analysis and modelling of the system is carried out mathematically. The responses of the system are examined by using matlab simulation fur the variation of the major parameters in view of reverse engineering. Consequently the validity of the established parameters are examined.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.33-41
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• 2010

There are several overvoltages by abnormal conditions in power system. We need to calculate these ovevoltages for the insulation design and the fault analysis. For these calculations, we used EMTP(Electro-magnetic Transients Program). During EMTP calculations, the accurate modelling of the equipments is very important for analysis results. In this paper, we considered the effects of the modelling condition's changes for transmission line within EMTP modelling cases of overvoltage analysis. Specially, we considered CB closing cases of 765[kV] system. So, we had changed the calculation frequencies of Line Constants, which is used for CB closing cases. In addition, we compared the calculation result and the measured result.

• 환경영향평가
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• 제13권4호
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• pp.213-222
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• 2004

Exergy is defined as the amount of work (entropy-free energy) a system can perform when it is brought into thermodynamic equilibrium with its environment. Exergy measures the distance from the inorganic soup in energy terms. Therefore, exergy can be considered as fuel for any system that converts energy and matter in a metabolic process. The aim of this study is to introduce structural dynamic modelling which is based on maximum exergy principle. Especially, almost ecological models couldn't explain algal succession until now. New model (structural dynamic model) is anticipated to predict or explain the succession theory. If the new concept using maximum exergy principle is used, algal succession can be explained in many actual cases. Therefore, It is estimated that structural dynamic model using maximum exergy principle might be a excellent tool to understand succession of nature from now on.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.581-584
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• 1998

This paper presents a scheme for fuzzy modelling and control of continuous-time nonlinear systems using a genetic algorithm. A fuzzy model is characterized by fuzzy "if-then" rules whose consequence part has a linear dynamic equation as subsystem of the system. The parameters of the fuzzy model are adjusted by a genetic algorithm. Then a tracking controller which guarantees stability of the overall system is designed. The simulation result demonstrates the effectiveness of the proposed method.

• 한국습지학회지
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• 제14권3호
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• pp.385-397
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• 2012

격자 기반의 물리적 분포형 모형은 유역의 물리적 매개변수와 격자 형식의 공간 및 수문자료를 이용해서 유출해석을 수행한다. 본 연구에서는 격자 기반의 물리적 분포형 강우-유출 모형인 GRM(Grid based Rainfall-runoff Model)의 실시간 유출해석 모듈인 GRM RT(Real Time)를 이용해서 실시간 유출해석 시스템을 개발하였다. 실시간으로 수신되는 기상레이더 자료를 기상청의 실시간 AWS 자료를 이용하여 보정한 후 유출해석에 적용하며, 수위관측소 자료로부터 생성되는 유량자료를 이용해서 유출모형을 실시간 보정한다. 본 연구에서는 실시간 유출해석 시스템 구축을 위해서 필요한 데이터베이스를 설계 및 구현하였으며, 분포형 모형과 레이더 자료를 이용한 실시간 유출해석 절차를 정립하였다. 또한 개발된 시스템의 성능을 평가하고 실시간 모형보정에 대한 적용성을 평가하였다. 소양강댐 상류에 위치한 내린천 수위관측소 유역을 대상으로 실시간 유출해석 시스템을 적용하고 그 결과를 평가하였다.

• 대한교통학회지
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• 제21권1호
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• pp.147-156
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• 2003

교통문제는 사회시스템이 복잡해짐에 따라 더욱 대처하기 어려운 국면으로 가고 있다. 따라서 교통시스템의 변화 예측도 용이하지 않다. 복잡계(complex system)의 하나로 볼 수 있는 교통시스템을 대처하는데 있어 전통적인 상의하달(上意下達) 접근에 한계가 있음을 부인할 수 없다. 지난 10여년 동안 물리학, 시스템공학, 컴퓨터공학 분야 등 다양한 분야에서 복잡계에 대한 활발한 연구가 진행되고 있다. 복잡계의 해석을 위한 새로운 개념과 접근기법들이 도입되고 있는데, 그들 중 에이젠트기반모형(agent-based modelling)은 교통분야에 적용 가능한 매우 흥미를 있는 기법으로 보인다. 본 글에서는 에이젠트기반모형이 무엇이며, 어떻게 사용되고 있으며, 교통분야에서의 적용가능성을 검토하였다. 본 글에서 제시한 에이젠트기반접근은 기존 방법과는 다른 하의상달(下意上達) 방식의 기법이다. 이는 시스템의 개별 구성원인 에이젠트의 행태와 에이젠트간의 상호작응에 초점을 둔다. 에이젠트의 행태와 상호작용의 규칙이 변함에 따라 전 에이젠트시스템에 나타나는 변화를 추적할 수 있다. 오늘날 교통문제의 복잡성은 교통시스템의 더욱 세분화된 하부시스템의 다양화와 상호작용, 그리고 개별 차량 또는 운전자의 행태와 상호작용에서 기인된다고 볼 수 있다. 따라서 에이젠트기반의 접근은 아직 연구는 미흡하지만 복잡한 교통시스템의 운영과 분석에 적용잠재력이 큰 기법으로 판단된다.

• International journal of advanced smart convergence
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• 제7권4호
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• pp.84-91
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• 2018

In this paper, we simulated three different HV systems and analyzed of each vacuum characteristics by VacCAD modelling. In each of modelled vacuum systems, selection of chamber materials, combination of rough pump with high vacuum pump and conductance of roughing line (diameter and length) were proposed as system variables. In the modelling of chamber materials, the pumping times to ultimate pressures of different chamber materials (stainless steel, aluminum) were compared by the variations of chamber volume. In this model, the effects of outgassing dependent on the chamber materials was also simulated and aluminum was estimated to optimum chamber materials. It was also obtained that modelling of vane and roots pump with diffusion pump and diameter, length of $50{\times}250$ [mm]roughing line were characterized as optimum variables to reach the ultimate pressure of 10E-7 [mbar] most effectively. Optimum design factors for vacuum characteristics of modelled vacuum system were achieved by VacCAD simulations. Feasibility of VacCAD as vacuum simulator was verified and applications of VacCAD expected to be increased to fields in vacuum needed.

• Structural Monitoring and Maintenance
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• 제4권3호
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• pp.195-220
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• 2017

Nowadays, railway system plays a significant role in transportation, conveying cargo, passengers, minerals, grains, and so forth. Railway ballasted track is a conventional railway track as can be seen all over the world. Ballast, located underneath the sleepers, is the most important elements on ballasted track, which has many functions and requires routine maintenance. Ballast needs to be maintained frequently to prevent rail buckling, settlement, misalignment so that ballast has to be modelled accurately. Continuum model was introduced to model granular material and was extended in ballast. However, ballast is a heterogeneous material with highly nonlinear behaviour. Hence, ballast could not be modelled accurately in continuum model due to the discontinuities nature and material degradation of ballast. Discrete element modelling (DEM) is proposed as an alternative approach that provides insight into constitutive model, realistic particle, and contact algorithm between each particle. DEM has been studied in many recent decades. However, there are limitations due to the high computational time and memory consumption, which cause the lack of using in high range. This paper presents a review of recent ballast modelling with benefits and drawbacks. Ballast particles are illustrated either circular, circular crump, spherical, spherical crump, super-quadric, polygonal and polyhedral. Moreover, the gaps and limitations of previous studies are also summarized. The outcome of this study will help the understanding into different ballast modelling and particle. The insight information can be used to improve ballast modelling and monitoring for condition-based track maintenance.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권6호
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• pp.261-268
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• 2005

This paper propose the safety design of automatic train control system which is used for controlling and monitoring train speed not to excess a permitted speed. Safety activities are shown for the computerized system to achieve a required safety requirement. The safety activities are composed of system dynamic modelling to identify potential hazards contained in the target system, to analyze sub system faults to provoke the hazards. Risks analysis are carried out to estimate losses caused from the hazards to allocate safety requirement. We Proposed design solutions for sub system to meet safety requirement.

• 한국정밀공학회지
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• 제9권1호
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• pp.96-105
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• 1992

A study on the construction of a CAD/CAM system operated by 16 Bit PC basic language, for machining sculptured surface of die, was carried out. The system consists of 2 steps i.e., process for geometric modelling by wire frame and process for machining data generation. Geometric modelling for sculptured surface is made by the point data fitting, parallel sweeping, normal sweeping and linear connection of cross section curve. Machining data are gained by cutter off-set of geometric model data and machining carried out by DNC. This system is to be proved enough for rough cutting by actual machining experiment. But, for becoming a high level system, another method of cutter off-set has to be regarded and system must be reconstructed by another program language.