• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.528-537
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• 2008

Primary frequency control(PFC) has the ability to regulate short period random variations of frequency during normal operation conditions and also to respond rapidly to emergencies. However, during the past decade, numerous significant sized blackouts occurred worldwide that resulted in serious economic losses. Therefore, the conclusion has been reached that the ability of the current PFC to meet an emergency is poor, and security of power systems should be improved. An alternative to enhance the PFC and thus security is to store excessive amounts of energy during off-peak load periods in efficient energy storage systems for substituting the primary control reserve. In this sense, superconducting magnetic energy storage(SMES) in combination with a static synchronous compensator(STATCOM) is capable of supplying power systems with both active and reactive powers simultaneously and very rapidly, and thus is able to enhance the security dramatically. In this paper, a new concept of PFC based on incorporating a STATCOM-SMES is presented. A complete detailed model is proposed and a new control scheme is designed, comprising an enhanced frequency control scheme, and a fully decoupled current control strategy in d-q coordinates with a novel controller to prevent dc bus capacitors voltage drift/imbalance. The performance of the proposed control schemes is validated through digital simulation carried out using MATLAB/Simulink.

• 한국컴퓨터그래픽스학회논문지
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• 제3권2호
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• pp.15-25
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• 1997

본 논문은 대규모 가상 세계의 제작 과정과 내비게이션에 관한 접근 방법을 기술하고, 그 과정에서 발견한 문제점과 개선 방향, 그리고 관련된 연구 이슈에 대해서 논한다. 대상 가상 세계로서 KAIST캠퍼스를 택하여 캠퍼스의 지형, 건물 및 구조물들을 모델링하고 배치하여 통합된 가상 세계를 구축하였다. 대규모 가상 세계를 제작하는 것은 그 자체가 중요한 연구 이슈가 될 뿐만 아니라 제작된 가상 세계는 캠퍼스 안내 시스템, 원격 교육, 디지털 라이브러리, 인터넷 응용 등에 사용될 수 있으며 실시간 컴퓨터 그래픽스를 연구하기 위한 testbed로 사용될 수 있다.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.754-760
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• 2012

To improve the efficiency and economics of national defence, the needs for defence M&S systems are greatly increased, but the lack of interoperability and reusability lowers the level of reliability in the existing simulations models. Recently, many research activities have been performed and some conceptual models, such as CMMS, DCMF, and KAMA, were introduced. However, these models don't support the whole process of defence M&S system development nor provide integrated domain knowledge and up-to-date data. In this paper, we analyzed the analysts' guidances and doctrines, which are the basic ingredients for the simulation system development, and proposed a systematic structure for all the defence M&S stakeholders to share the standardized domain knowledge, modeling algorithm and data. This will be a logical bridge between Mission Space and Simulation Space, and provide substantial data sets to build simulation systems.

• International Journal of Precision Engineering and Manufacturing
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• 제6권4호
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• pp.3-7
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• 2005

Recently, vehicle simulators are widely used to evaluate driver s responses and driver assistance systems. It needs much effort to construct the virtual driving environment for a vehicle simulator. In this study, it is described how to make effectively the roads and the driving environment for a vehicle simulator. GIS (Geographic Information System) is used to construct the roads and the environment effectively. Because the GIS is the integrated system of geographical data, it contains useful data to make virtual driving environment. First, boundaries and centerlines of roads are extracted from the GIS. From boundaries, the road width is calculated. Using centerlines, mesh models of roads are constructed. The final graphic model of roads is constructed by mapping road images to those mesh models considering the number of lanes and the kind of surface. Data of buildings from the GIS are extracted. Each shape and height of building is determined considering the kind of building to construct the final graphic model of buildings. Then, the graphic model of roadside trees is constructed to decide their locations. Finally, the driving environment for driving simulator is constructed by converting the three graphic models with the graphic format of Direct-X and by joining the three graphic models.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1482-1494
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• 2022

Power conversion cycles (Subcritical Steam, Supercritical Steam, Open Air Brayton, Recuperated Air Brayton, Combined Cycle, Closed Brayton Supercritical CO₂ (sCO₂), and Stirling) are evaluated for land-based nuclear microreactors based on technical maturity, system efficiency, size, cost and maintainability, safety implications, and siting considerations. Based upon these criteria, Air Brayton systems were selected for further evaluation. A brief history of the development and applications of Brayton power systems is given, followed by a description of how these thermal-to-electrical energy conversion systems might be integrated with a nuclear microreactor. Modeling is performed for optimized cycles operating at 3 MW(e) with turbine inlet temperatures of 500 ℃, 650 ℃ and 850 ℃, corresponding to: a) sodium fast, b) molten salt or heat pipe, and c) helium or sodium thermal reactors, coupled with three types of Brayton power conversion units (PCUs): 1) simple open-cycle gas turbine, 2) recuperated open-cycle gas turbine, and 3) recuperated and intercooled open-cycle gas turbine. Aeroderivative turboshaft engines employing the simple Brayton cycle and two industrial gas turbine engines employing recuperated air Brayton cycles are also analyzed. These engines offer mature technology that can facilitate near-term deployment with a modest improvement in efficiency.

• 한국BIM학회 논문집
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• 제14권1호
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• pp.30-38
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• 2024

This study aims to propose a smart city governance logic model that can accommodate more diverse information service systems by mixing hub-and-spoke and blockchain technologies as a data management model. Specifically, the research focuses on deriving the logic of an operating system that can work across smart city planning based on the two data governance technologies. The first step of the logic is the generation and collection of information, which is first divided into information that requires information protection and information that can be shared with the public, and the information that requires privacy is blockchainized, and the shared information is integrated and aggregated in a data hub. The next step is the processing and use of the information, which can actively use the blockchain technology, but for the information that can be shared other than the protected information, the governance logic is built in parallel with the hub-and-spoke type. Next is the logic of the distribution stage, where the key is to establish a service contact point between service providers and beneficiaries. Also, This study proposes the establishment of a one-to-one data exchange relationship between information providers, information consumers, and information processors. Finally, in order to expand and promote citizen participation opportunities through a reasonable compensation system in the operation of smart cities, we developed virtual currency as a local currency and designed an open operation logic of local virtual currency that can operate in the compensation dimension of information.

• 대한기계학회논문집A
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• 제25권5호
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• pp.788-796
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• 2001

VR(Virtual reality) technologies have given engineers the ability to design, test, and evaluate engineering systems in a virtual environment. The virtual plant is the highlight of the application of the VR technology to plant engineering. Plant design, maintenance, control, management, operation are integrated in the virtual plant. The VR monitoring system including the concept of the virtual plant is developed to replace a current control room that has number of gages and warning lamps in two-dimensional panels which shows the operating status of a plant. The operating status of the plant is displayed in the VR monitoring system through the realistic computer graphics. Sophisticated, realistic and prompt control becomes possible. The VR monitoring system consists of advanced visualization, walk-through simulation and navigation. In the virtual environment, a user can navigate and interact with each component of a plant. In addition, the user can access the information by just clicking interesting component. The VR monitoring system is operated with various modules, such as (1) virtual plant constructed with Graphic Management System (GMS), (2) Touch & Tell System, and (3) Equipment DB System of Part. In order to confirm the usefulness of the VR monitoring system, a pilot gas plant which is currently being used for plant operator training is taken as application. The end of the paper gives an outlook on the future work and a brief conclusion.

• 한국컴퓨터정보학회논문지
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• 제25권12호
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• pp.261-270
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• 2020

본 연구는 피기백 화차운송 시스템의 특허문서를 활용하여 관련 분야의 유망기술을 파악하는 것을 목표로 한다. 이를 위해 피기백 운송 시스템의 선행연구 및 관련 보고서로 기술 키워드를 추출하여 특허문서를 추출한다. 추출된 특허문서에 텍스트마이닝 기법을 적용하여 빈도수가 높은 키워드를 확인하고 피기백 운송 시스템의 핵심기술의 토픽을 식별하기 위해 LDA(Latent Dirichlet Allocation) 알고리즘을 적용하였다. 마지막으로, 시계열 분석 기법인 ARIMA 모델을 핵심기술의 토픽에 적용하여 기술 추세를 예측하고 피기백 운송 시스템에 대한 유망한 기술을 식별하였다. 특허 분석 결과, 데이터 기반 통합관리 시스템과 운영 계획 시스템 그리고 복합수송 중 특수 화물(기체, 액체류) 운송 및 보관 기술이 미래에 유망한 핵심기술로 도출되었고, 데이터 송수신 및 분석 기술이 중요한 세부 기술임을 확인하였다. 제안된 분석 방법은 피기백 운송 시스템의 R&D 연구개발 전략 및 기술 로드맵을 개발하는 데 있어 충분한 자료가 될 수 있다.

• Spatial Information Research
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• 제13권3호
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• pp.309-321
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• 2005

교통정책과 계획수립을 위한 교통수요의 합리적인 분석을 위해서는 현실적이고 신뢰성 있는 교통자료의 구축이 요구된다. 또한 교통계획 및 운영의 측면에서 복잡한 교통문제를 쉽게 전달할 수 있는 사용자 위주의 시스템이 필요하다 일반적으로 교통 분석 존에 대한 사회${\cdot}$경제적 특성 자료를 수집하고 분석용 네트워크를 구축하는 과정은 교통계획모형 수립과정에서 가장 중요한 부분으로 많은 시간과 노력이 요구된다. 또한 수집된 데이터를 통합하고 이용 가능한 형식으로 변화하기 위해서는 상당한 비용이 든다. 이러한 문제점을 해결하기 위해서는 자료를 효과적으로 선택, 수정, 가시화할 수 있고, 네트워크의 특성 변화를 보다 효율적으로 파악할 수 있도록 GIS를 도입하는 것이 바람직하다. 교통계획과정에 GIS의 기능이 특히 중요시되어지고 있지만 교통문제에 GIS를 이용하는 것은 초보적인 단계이다. 본 연구는 GIS의 공간표현, 분석기능을 바탕으로 다양한 교통정보를 제공하고 교통계획을 가능하게 하기 위한 GIS-T 통합시스템 구현에 목적을 두었다. 이를 위해 교통분석용 패키지와 GIS 환경사이에 양방향 데이터 교환이 가능하게 하고, 네트워크 수정${\cdot}$편집${\cdot}$검수기능 등 보다 효율적인 교통네트워크 관리를 위한 인터페이스를 설계하였다. 또한 GIS가 가지는 공간 데이터의 효과적인 처리에 활용가능 하도록 교통정보 처리모듈을 개발하여 통합시스템에 추가하였다. 이러한 GIS-T 통합시스템은 네트워크의 편집과 분석에 효율적인 환경을 제공하여 보다 현실적인 교통망 모델링을 반영할 수 있으며, 다양한 교통문제 분석에 효과적인 도구로 활용될 수 있을 것이다.

• 한국농공학회논문집
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• 제60권6호
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• pp.1-12
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• 2018

The objectives of this study were to develop a system linking hydrologic and water quality models considering the mechanisms of agricultural reservoir and paddy cultivation and to evaluate whether the developed system simulates hydrologic and water quality processes better than a hydrologic model that do not consider the mechanisms. The system consisted of Hydrological Simulation Program-Fortran (HSPF) as a watershed model, Module-based hydrologic Analysis System for Agricultural watersheds (MASA) as reservoir water balance model, and Chemical, Runoff and Erosion from Agricultural Management System-Paddy (CREAMS-PADDY) as a hydrologic and water quality model for paddy fields. This study carried out on the Seolseong-Cheon watershed in Icheon, and the water level and water quality had been monitored for two years at the outlet of the watershed. According to the results of this study, the performance of the simulation using HSPF-MASA-CREAMS-PADDY system was better than others, but they did not show a statistically significant difference. This seemed to be due to the uncertainty of the farming data and the water quality data of the reservoir. Therefore, if accurate input data for the system is obtained, HSPF-MASA-CREAMS-PADDY system could be used to model an agricultural watershed to obtain more realistic results. The results of this study could be utilized to the modeling of agricultural watersheds in Korea where paddy rice cultivation is dominant.