• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2979-2984
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• 2013

This paper proposes a modeling and controller design method of Flywheel Energy Storage System(FESS) for solving the unstable operation problem in hybrid generation system with wind turbine and diesel generator applied in island area. FESS is considered as a permanent magnetic synchronous machine connected to flywheel because of its efficiency. The controller of FESS is composed of AC/DC/AC back-to-back converter. The AC/DC converter is designed to charge/discharge according to the frequency variation and the DC/AC converter to operate to keep the DC bus voltage constant. The proposed modeling and controller design method of FESS was applied to hybrid generation system with wind turbine and diesel generator. The unstable operation problem owing to wind variations was solved through simulation results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6274-6281
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• 2015

Radio-based train control system has driving headway shortening effect by real-time train interval control using two-way radio communication between onboard and wayside systems, and reduces facility investment because it does not require any track-circuit. Automatic train protection(ATP), the most significant part of the radio-based train control system, makes sure a safe distance between preceding and following trains, based on real-time train location tracing. In this paper, we propose the overall ATP train interval control algorithm to control the safe interval between trains, and preprocessing-based speed profile calculation algorithm to improve the processing speed of the ATP. The proposed speed profile calculation algorithm calculates the permanent speed limit for track and train in advance and uses as the most restrictive speed profile. If the temporary speed limit is generated for a particular track section, it reflects the temporary speed limit to pre-calculated speed profile and improves calculation performance by updating the speed profile for the corresponding track section. To evaluate the performance of the proposed speed profile calculation algorithm, we analyze the proposed algorithm with O-notation and we can find that it is possible to improve the time complexity than the existing one. To verify the proposed ATP train interval control algorithm, we build the train interval control simulator. The experimental results show the safe train interval control is carried out in a variety of operating conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.115-115
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• 2003

최근 회전기계에 대한 세계적인 기술추세를 볼 때 해를 거듭할수록 더욱 정밀해지고 고속화에 대한 요구가 한층 증대되고 있으며 이러한 측면에서 여러 분야에 우수한 장점을 지니고 있는 능동적 자기베어링의 회전축계 활용에 대한 연구가 활발히 진행되고 있다. 특히 프랑스를 중심으로 한 미국, 일본 등이 이에 대한 연구를 활발하게 수행하여 고속 공작기계 스핀들을 비롯한 고진공 펌프 및 각종 터어빈, 압축기 등에 실용화시키는 단계에 있다. 그러나 국내 관련기술에 대한 연구는 연구소, 학계를 중심으로 실험실적인 기초연구로서 부분적으로 수행하는 단계에 있으며 관련분야 활용을 위한 본격적인 연구는 수행되지 못하고 있는 실정이고 이를 실용화시키기 위한 일환으로 능동적 자기 베어링의 회전 축계를 구성하고 있는 요소기술 중 하나인 전력 증폭기의 개발이 이뤄져야 할 필요성이 있는데 본 논문에서는 네트웍 기반 전력 증폭기 개발을 시도하였다. 전력 증폭기는 크게 리니어 앰프와 스위칭 앰프로 구분된다. 리니어 앰프의 경우 회로가 간단하고 노이즈가 비교적 작다는 장점이 있지만 전력손실 및 발열이 크기 때문에 에너지 측면에서 저 효율이라는 점과 따로 방열판을 부착해야 한다는 단점을 가지고 있고, 스위칭 앰프의 경우 전력손실이 작은 반면, 회로가 비교적 복잡하고 노이즈의 발생 가능성이 높다는 단점이 있다. 본 논문에선 위 두 가지 방식을 혼합한 혼합형 전력 증폭기로 설계하였다. 또한 기존에 전력증폭기의 경우 상위 주제어기로부터 제어량을 아날로그 신호로 통신하기 때문에 발생할 수 있는 EMI 노이즈신호에 대한 대책을 세워야 하는데 본 연구를 통해 개발된 전력증폭기는 따로 보조제어기(TMS320LF2406A)를 두어 상위 주제어기에 전력증폭기의 상태값을 궤환할 수 있도록 명령 신호체계를 전체 시스템의 샘플링 시간을 고려하여 비교적 전송 속도가 빠른 CAN(Controller Area Network)으로 구축하여 주제어기와 전력 증폭기간에 양방향 통신이 가능하도록 하였다. 이로써 전력증폭기의 상태정보를 알 수 있다. 따라서 본 논문에서는 칩 설계기술의 발전으로 가격대 성능비가 우수한 DSP(TMS320LF2406A)를 이용하여 과거의 아날로그 방식의 명령신호체계를 디지털 신호체계로 바꿈으로써 네트웍을 통해 전력증폭기의 상태진단 가능성을 검증한다.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.89-100
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• 2008

In an urban network controlled by traffic signals, there is an interaction between the signal timing and the routes chosen by individual road users. This study develops a bi level programming model for traffic signal optimization in networks with path based traffic assignment. In the bi level programming model, genetic algorithm approach has been proposed to solve upper level problem for a signalized road network. Path based traffic assignment using column generation technique which is proposed by M.H. Xu, is applied at the lower-level. Genetic Algorithm provieds a feasible set of signal timings within specified lower and upper bounds signal timing variables and feeds into lower level problem. The performance of this model is investigated in numerical experiment in a sample network. In result, optimal signal settings and user equilibrium flows are made.

• Journal of Energy Engineering
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• v.2 no.1
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• pp.104-113
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• 1993

Due to steady increase of electric power demand and decrease of load factor, the economic and reasonable operation of electric power system is necessary. Because of this reason, dispersed battery energy storage system(BESS) with fast response is receiving attractive attention. With these considerations, 20 kVA BESS is designed and tested to investigate the possibility of BESS application to power system. This paper describes the design specifications of simulator and test results. BESS is composed of batteries, conversion equipments, interconnecting equipments to power system, and control parts of the system. The inverter of BESS can carry out two functions as charger and discharger. Also, it can operate as a VAR compensator by four quadrant operation. Since this system is designed as a simulator of MW system, the conceptual design of MW system is possible by using the test result of test system The study of BESS is preliminary stage for the future MW class BESS.

• 기계와재료
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• v.22 no.3
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• pp.88-95
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• 2010

국내외 대형 플랜트사업이 활발해지면서 여기에 소요되는 건설기계의 수요가 급증하고 특히 초 대형화가 요구되고 있다. 그러나 국내 건설기계는 장비중량이 40ton 이하인 것을 주로 생산하고 있었으나, 최근 이것에 2배가 넘는 85ton급 초대형을 생산하고 있다. 주행모터(track motor)는 굴삭기의 전진 및 후진 주행을 하는 핵심 부품으로서 유압카운터 밸런스 밸브, 양방향작동 릴리프밸브, 주차 브레이크 장치, 2속 제어장치, 유압모터와 고 강성 유성기어감속기가 매우 콤팩트한 구조로 구성된다. 우리나라에서는 두산모트롤, 제일유압, 선진정공 등에서 40ton 이하의 중소형 건설기계용 주행모터를 생산하고 있으나, 70ton 이상 초대형 급은 일본 Kayaba사, Kawasaki사, 독일 Rexroth사 및 이태리 Trasmital사 들로부터 전량수입에 의존하고 있다. 본고에서는 건설기계의 핵심부품인 주행모터의 국내외 수요시장 동향을 분석하여 국산화 개발필요성을 강조하였고, 특히 초대형 주행모터의 성능특성을 분석하여 국산화 개발에 반영 할 수 있도록 하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1043-1052
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• 2009

In this work, a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. Since the measurable variables are the positions and rates of master/slave motors, only a constrained specific bilateral control structure is available. In the consideration of the flexibility of the tendon and constrained control structure, we derived a necessity for tendon design to prevent uncontrollable vibration mode through a modal analysis. Based on a reduced rigid body model, a control design was suggested and tendons were selected. The feasibility of the proposed analysis and tendon design were verified along with some simulation results.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.969-971
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• 2000

This paper deals with characteristics analysis of Doubly-Fed Induction Generator (DFIG) in the supersynchronous speed regions. by control of voltage fed to the rotor using for bidirection control. This rotor voltage is controlled by con troll of inverter switching frequency and fire angle. Characteristics of DFIG is analyzed by steady-state algebraic equations of the equivalent circuit using numerical analysis. And it is compared with results of experiment. Consequently, this paper presented to find the optimal magnitude of voltage fed to the rotor for maximum power and PF, using result of characteristics analysis.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.267-268
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• 2019

제안하는 모듈을 기반한 고승압 및 고용량 DC/DC 컨버터는 직류 탭리액터를 인터리브드 형태와 결합한 승압형 컨버터를 모듈화하여 변압기 턴비를 작게 할 수 있고 스택을 통해 고승압에 유리하다. 연료전지 응용분야에 적용가능하며 추후 양방향제어를 통하여 전기자동차와 같은 견인구동 응용분야에도 적용할 수 있는 장점이 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.660-665
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• 2018

Research into underwater wireless networks that enable the monitoring and controlling of the ocean environments has been continuing for disaster prevention and military proposes, as well as for the exploitation of ocean resources throughout the world. A research group led by Hoseo university has been studying a distributed underwater monitoring and controlling network. In this study, we developed an interpolator for acoustic communication between an underwater base station controller and underwater base station, which is included in this network. The underwater acoustic communication provided by this network defines four links whose sampling rates are different. Low power consumption is one of the most important requirements. Therefore, we adopted CIC interpolators, which are known to act as filters with a low power consumption, and some CIC interpolators with an appropriate changing rate were selected depending on the link. However, these interpolators have a large passband drop and wide transition region. To solve these problems, we added a compensator and half-band filter. After verifying the algorithm by using Matlab, we designed and verified it with Verilog-HDL in a ModelSim environment.