• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.49-55
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• 1996

Recently, the necessity for more accurate automatic gauge control has increased of customers' requirement for cold rolled steel sheets with thinner gauge and better gauge quality. Therefore, many cold rolling mills replaced its electric screw down automatic gauge control system with a new hydraulic automatic gauge control system, to ensure closer gauge tolerance. In this paper, The performance of a hydraulic automatic gauge control system for cold rolling has been investigated under industrial conditions. It was investigated that variation of gauge deviation according to the final products thickness, cold rolling speed and pass number, in the actual rolling mill. As a result, it was found that the system enables strip thickness variation to be reduced substantially and caused by poor gauge deviation have been drastically decreased. The test results are as following. The more the exit steel strip thickness is thick, the smaller the aguge deviation rate is large, and the more it is thin, the large the gauge deviation rate is large. Because the gauge deviation is larger at accleration speed and deceleration speed than steady speed, so automatic gauge control system is better to adopt over 50m/min. automatic gauge control system reduces rapidly large thickness deviation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.85-92
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• 2016

The paper presents a method to assess system voltage sag performance considering sag durations as well as magnitudes. In general, voltage sag assessment for large power systems is performed only considering sag magnitudes at sensitive load points. However some equipment can be affected by certain sag durations. The duration of the voltage sag is depend on the time of fault current flow in the system. Therefore, the duration can be determined by analyzing the operating characteristic of the protection system. In this paper, an effective method to evaluate sag durations regarding the characteristics and failure rates of the protection system is described. The proposed method can be used to assess the long-term performance of the voltage sags in large power system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.589-595
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• 2004

This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations, starting of large induction motor and three-phase fault in the system, and investigates voltage variations of the system for disturbances. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. The simulation results show the variation of the generator torque, the generator rotor speed, the pitch angle, terminal voltage, system voltage, fault current, and real/reactive power output, etc. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations, starting of a large induction motor causes a voltage sag due to a large starting current, and a fault on the system influences on the output of the wind turbine generator.

• Korean Journal of Computational Design and Engineering
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• v.13 no.6
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• pp.412-420
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• 2008

In order to design the large complex structures like VLFS (Very Large Floating Structures), it is essential the cooperation between the experts in various fields; structural engineering expert, fluid mechanics expert, mooring system engineer, and so on. This paper describes the development of an integrated system to support the cooperative design between various experts and project manager. This integrated system is designed to be operated in Web environment and it contains the support of design DB and 3D graphical tool, negotiation tool for task allocation, and various engineering supporting tools for each design step. The user group of this system can be classified as Project Manager, Engineering Expert, DB Builder, and System Administrator. All of the engineering data is saved after and during the process of the design projects and all participants can be connected by Internet without the limit of time or space constraints.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.463-478
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• 2019

The most important non-functional requirements for dependability of any Embedded Real-Time Safety Systems are safety, availability and reliability requirements. System architecture plays the primary role in achieving these requirements. Compliance with these non-functional requirements should be ensured early in the development cycle with appropriate considerations during architectural design. In this paper, we present an application of system architecture modeling for quantitative assessment of system dependability. We use probabilistic model checker (PRISM), for dependability analysis of the DTMC model derived from system architecture model. In general, the model checking techniques do not scale well for analyzing large systems, because of prohibitively large state space. It limits the use of model checking techniques in analyzing the systems of practical interest. We propose abstraction based compositional analysis methodology to circumvent this limitation. The effectiveness of the proposed methodology has been demonstrated using the case study involving the dependability analysis of safety system of a large Pressurized Water Reactor (PWR).

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.113-117
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• 1989

Generally, stabilization system is surely needed for the compensation of the ship motion. In this paper, the study investigated stabilizer design for the large driving system. We make a performance analysis for the stabilization scheme through the computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.547-549
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• 1986

This paper deals with large scale distributed packet switching system which is modeled by state space form and optimizing routing algorithms and buffer size via a hierachical system optimization method, the interaction prediction method.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.1-6
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• 2017

The advanced driver assistant system (ADAS) requires the collection of a large amount of information including road conditions, environment, vehicle status, condition of the driver, and other useful data. In this regard, large-scale sensor networks can be an appropriate solution since they have been designed for this purpose. Recent advances in sensor network technology have enabled the management and monitoring of large-scale tasks such as the monitoring of road surface temperature on a highway. In this paper, we consider the estimation and fusion problems of the large-scale sensor networks used in the ADAS. Hierarchical fusion architecture is proposed for an arbitrary topology of the large-scale sensor network. A robust cluster estimator is proposed to achieve robustness of the network against outliers or failure of sensors. Lastly, a robust hierarchical data fusion scheme is proposed for the communication channel between the clusters and fusion center, considering the non-Gaussian channel noise, which is typical in communication systems.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.375-380
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• 2007

맥락 정보와 맥락 인식 시스템에 대한 연구는 지난 10 여 년 동안 유비쿼터스 컴퓨팅 분야에서 중요한 이슈로 다루어졌다. 대부분의 맥락 인식 시스템은 위치 정보와 같이 단일 형태의 맥락 정보를 위해서 설계되었거나 연구실 수준의 크기로 제한되었다. 그러나 많은 종류의 센서와 actuator 를 포함하고 다수의 관리 도메인으로 확장 가능한 스케일이 큰 시스템에 대한 개발 및 평가는 여전히 미흡한 수준이다. 특히, 맥락 퓨전과 추론 구조를 가지는 Large-scale 의 맥락 인식 시스템에 대한 평가 방법이 필요한 실정이다. 본 논문에서는 휴리스틱 평가를 이용한 Large-scale 맥락 인식 시스템의 평가 방법에 대하여 제안한다. 그리고 우리는 동적인 맥락 인식 시스템을 지원하고 맥락 퓨전 및 추론을 위한 메커니즘을 포함하는 기본 구조에 대해서 자세히 설명한다. 맥락 인식 시스템 평가를 위해서 제안된 접근법은 사용자 인터페이스 도메인에서 잘 알려진 전문가에 의한 평가 방법으로 Large-scale 맥락 인식 시스템에 적합하도록 특별히 선택된 heuristics 집합을 이용하는 휴리스틱 평가(Heuristic Evaluation)이다.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.315-322
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• 2011

High-accuracy micropatterns such as V-shaped microgrooves are increasingly in demand for various engineering areas. And the technical trend goes for large surface areas in precision machining technology. So micropatterns with large surface areas are expected to play an increasingly important role in today's manufacturing technology In this study, we focused on developing machining technologies. First, a machine vision system for precise tool setting is developed. Second, an on-machine measurement (OMM) system for large-area measurement is implemented. And also software for tool path generation and simulation is developed. With these technologies we fabricated large-surface micropatterns in an electroless nickel-plated workpiece with single-crystal diamond tools and a 32-in, $675mm{\times}450mm$ mold with tens of V-and pyramid-shaped micropatterns.