• 한국위성정보통신학회논문지
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• 제12권4호
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• pp.72-77
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• 2017

위성항법보강시스템 (Satellite Based Augmentation System; SBAS)은 정지궤도(GEO) 위성들을 이용하여 GPS, GLONASS 등의 위성항법시스템 (Global Navigation Satellite System; GNSS) 사용자들에게 무결성 데이터 및 정정 데이터를 방송하는 데 목적이 있다. 국제민간항공기구 (International Civilian Aeronautical Organization; ICAO)의 2025년까지 SBAS 도입 권고에 따라, 국토교통부 사업으로 한국형 SBAS 시스템 개발/구축 사업이 진행 중에 있다. 한국형 위성항법보강시스템인 KASS(Korea Augmentation Satellite System)는 초정밀 GPS 오차보정시스템으로, 기준국(KASS Reference Station; KRS), 중앙처리국(KASS Processing Station; KPS), 위성통신국(KASS Uplink Station; KUS) 및 통합운영국(KASS Control Station; KCS)으로 구성된 지상시스템과 GEO 위성으로 이루어져 있다. 본 논문에서는 KASS 지상 부문과 GEO 위성간의 연동 역할을 하며 신호생성부(Signal Generator Section; SGS)와 RF부(Radio-Frequency Section; RFS)로 구성된 KASS 위성통신국에 대해 개념적 설계를 하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권3호
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• pp.298-305
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• 2015

본 논문에서는 선박용 동기발전기 여자제어시스템의 성능을 확인하기 위해 선급기술규칙에 따라서 시행한 실험 결과를 제공한다. 실험에서는 발전기의 각 부하 변화에 대해 PID 제어기와 퍼지제어기를 적용하고 두 제어기법이 선급의 기술규칙을 만족하는 지 관찰하고 성능을 비교 검토 한다. 이를 위해 PID 제어기법과 퍼지제어기법을 랩뷰 프로그램으로 작성한 후, PID 제어기의 경우는 한계 감도법과 약간의 조정을 통해 이득값을 결정한다. 퍼지제어기는 맘다니(Mamdani)의 방법으로 전압오차값과 전압오차변화율값, 출력전압값에 대해 멤버쉽함수를 구성한다. 이상의 PID 제어기법과 퍼지제어기법을 실제 소형 발전기에 적용하고 선급기술규칙에 따른 실험을 통해 안정성과 성능개선 특성을 비교 검토한다.

• Transactions on Electrical and Electronic Materials
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• 제5권2호
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• pp.71-75
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• 2004

This paper proposes a new bandgap reference (BGR) circuit which takes advantage of a cascode current mirror biasing to reduce the V$\_$ref/ variation, and sizing technique, which utilizes two related ratio numbers k and N, to reduce the PNP BJT area. The proposed BGR is designed and fabricated on a test chip with a goal to provide a reference voltage to the 10 bit A/D(4-4-4 pipeline architecture) converter of the CMOS Active Pixel Sensor (APS) imager to be used in X-ray imaging. The basic temperature variation effect on V$\_$ref/ of the BGR has a maximum delta of 6 mV over the temperature range of 25$^{\circ}C$ to 70$^{\circ}C$. To verify that the proposed BGR has radiation hardness for the X-ray imaging application, total ionization dose (TID) effect under Co-60 exposure conditions has been evaluated. The measured V$\_$ref/ variation under the radiation condition has a maximum delta of 33 mV over the range of 0 krad to 100 krad. For the given voltage, temperature, and radiation, the BGR has been satisfied well within the requirement of the target 10 bit A/D converter.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.317-320
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• 2011

과산화수소와 케로신을 이용한 이원액체추진제 로켓엔진을 위한 산화제 터보펌프를 설계하였으며 수류시험을 통해 설계된 터보펌프의 작동여부를 실험하였다. 과산화수소 터보펌프의 설계조건을 결정하고 펌프의 임펠러를 설계하였다. 펌프를 구동하기 위한 터빈을 차량용 터보차저로 선정하였으며 터빈 맵을 이용하여 가스발생기를 설계하였다. 펌프, 터빈과 가스발생기를 통합하여 터보펌프 시스템을 구축하였으며 수류시험을 통해 터보펌프 시스템이 1.47 bar의 압력으로 3.4 kg/s의 유량을 공급하는 것을 확인하였다.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2007-2015
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• 2005

A large-scale analysis to evaluate complex material and structural behaviors is one of interesting topic in diverse engineering and scientific fields. Also, the utilization of massively parallel processors has been a recent trend of high performance computing. The objective of this paper is to introduce a parallel process system which consists of general purpose finite element analysis solver as well as parallelized PC cluster. The later was constructed using eight processing elements and the former was developed adopting both hierarchical domain decomposition method and balancing domain decomposition method. Then, to verify the efficiency of the established system, it was applied for structural analysis of steam generator in nuclear power plant. Since the prototypal evaluation results agreed well to the corresponding reference solutions it is believed that, after reinforcement of PC cluster by increasing number of processing elements, the promising parallel process system can be utilized as a useful tool for advanced structural integrity evaluation.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.264-269
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• 2006

A $0.12GHz{\sim}1.4GHz$ DLL-based clock generator with the capability of multiplied four phase clock generation was designed using a 0.18um CMOS process. An adaptive bandwidth DLL with a regulated supply delay line was used for a multiphase clock generation and a low jitter. An extra phase detector (PD) in a reference DLL solves the problem of the initial VCDL delay and achieves a fast lock time. Twice multiplied four phase clocks were generated at the outputs of four edge combiners, where the timing alignment was achieved using a coarse lock signal and the 10 multiphase clocks with T/8 time difference. Those four clocks were combined one more time using a static XOR circuit. Therefore the four times multiplication was achieved. With a 1.8V supply, the rms jitter of 2.1ps and the peak-to-peak jitter of 14.4ps were measured at 1.25GHz output. The operating range is $0.12GHz{\sim}1.4GHz$. It consumes 57mW and occupies 450*325um2 of die area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1864-1866
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• 1996

Grounding is the art of making an electrical connection to the earth. In order to protect man, electrical and/or electric equipments from the lightning strokes, all the energy of lightning strokes must be diverted via a safe path to earth. It is essential to the transient grounding resistance against lightning strokes. In this paper, measurements and analyses of grounding surge impedance have been investigated. For measurements of grounding surge impedance the pulse generator was designed and fabricated. The pulse generator has rise time of 22.4 ns and pulse duration of $8\;{\mu}s$. The transient grounding resistance has been measuring by injecting low power and step current between the earthing system under test and a remote reference earth and measuring the potential rise caused by this current. As a result, the transient grounding resistance against lightning surge in the short time domain is much higher than steady state grounding resistance.

• Journal of Electrical Engineering and Technology
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• 제5권3호
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• pp.503-510
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• 2010

This paper proposes the use of fuzzy applications to a 4-machine and 10-bus system to check stability in open conditions. Fuzzy controllers and the excitation of a synchronous generator are added. Power system stabilizers (PSSs) are added to the excitation system to enhance damping during low frequency oscillations. A fuzzy logic power system stabilizer (PSS) for stability enhancement of a multi-machine power system is also presented. To attain stability enhancement, speed deviation ($\Delta\omega$) and acceleration ($\Delta\varpi$) of the Kota Thermal synchronous generator rotor are taken as inputs to the fuzzy logic controller. These variables have significant effects on the damping of generator shaft mechanical oscillations. The stabilizing signals are computed using fuzzy membership functions that are dependent on these variables. The performance of the fuzzy logic PSS is compared with the open power system, after which the simulations are tested under different operating conditions and changes in reference voltage. The simulation results are quite encouraging and satisfactory. Similarly, the system is tested for the different defuzzification methods, and based on the results, the centroid method elicits the best possible system response.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.82-91
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• 2014

The combined generator system by integrating several renewable energy sources can share the electrical infrastructure and therefore have the advantage of constructing not only the transmission system but also the power conversion system. Among the various combined renewable system, the wind power and wave power has a high possibility of future growth due to the economic feasibility in offshore environment. This kind of large-scale combined systems might be follow the determination by the transmission system operator's directions and control the output profile by focusing at PCC. However, both renewable energies are depend on the unpredictable environmental variation; it is needed to do the compensation devices. In this paper, the ESS compensation plan is proposed to do output determination of the combined generator system by paying attention to active power of utility grid with the analysis of the controllable elements of the wind and wave power generator. The improvement of the new application technique of the combined system is confirmed through using the PSCAD/EMTDC. The entire simulation process was designed by adopting the active power control according to the reference signal of TSO.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.801-809
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• 2016

The electrically excited synchronous generator (EESG) is applied in wind turbine systems recently. In an EESG control system, electrical torque is affected by stator flux and rotor current. So the control system is more complicated than that of the permanent-magnet synchronous generator (PMSG). Thus, the higher demanding of the control system is required especially in case of wind turbine mechanical resonance. In this paper, the mechanism of rotor speed resonant phenomenon is introduced from the viewpoint of mechanics firstly, and the characteristics of an effective damping torque are illustrated through system eigenvalues analysis. Considering the variables are tightly coupled, the four-order small signal equation for torque is derived considering stator and rotor control systems with regulators, and the bode plot of the closed loop transfer function is analyzed. According to the four-order mathematical equation, the stator flux, stator current, and electrical torque responses are derived by torque reference step and ramp in MATLAB from a pure mathematical deduction, which is identical with the responses in PSCAD/EMTDC simulation results. At last, the simulation studies are carried out in PSCAD software package to verify the resonant damping control strategy used in the EESG wind turbine system.