• Title/Summary/Keyword: 전자식 안정기

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Neural Equalization Techniques in Partial Erasure Model of Nonlinear Magnetic Recording Channel (부분 삭제 모델로 나타난 비선형 자기기록 채널에서의 신경망 등화기법)

  • Choi, Soo-Yong;Ong, Sung-Hwan;You, Cheol-Woo;Hong, Dae-Sik
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.12
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    • pp.103-108
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    • 1998
  • The increase in the capacity of the digital magnetic recording systems inevitably causes severe intersymbol interference (ISI) and nonlinear distortions in the digital magnetic recording channel. In this paper, to cope with severe ISI and nonlinear distortions a neural decision feedback equalizer (NDFE) is applied to the digital magnetic recording channel - partial erasure channel model. In the performance comparison of bit error probability (or bit error ratio : BER) between the NDFE and the conventional decision feedback equalizer (DFE) via computer simulations. It has been found that as nonlinear distortions increase the NDFE has more SNR (SIgnal-to-Noise Ratio) advantage over the conventional DFE. In addition, in spite of the same recording density, as nonlinear distortions are increased, NDFE has the better performance of BER and the greater stability over conventional DFE.

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Robust Speed Control of a Permanent Magnet Synchronous Motor using a Fuzzy Logic Controller (퍼지제어기를 이용한 영구자석 동기전동기의 강인한 속도제어)

  • Choi, Young-Sik;Yu, Dong-Young;Jung, Jin-Woo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.15 no.5
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    • pp.343-351
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    • 2010
  • This paper proposes a new fuzzy speed controller based on the Takagi-Sugeno fuzzy method to achieve a robust speed control of a permanent magnet synchronous motor (PMSM). The proposed controller requires the information of the load torque, so the second-order load torque observer is used to estimate it. The LMI condition is derived for the existence of the proposed fuzzy speed controller, and the gains of the controller are provided. It is proven that the augmented control system including the fuzzy speed controller and the load torque observer is exponentially stable. To evaluate the performance of the proposed fuzzy speed controller, the simulation and experimental results are presented under motor parameter variations. Finally, it is clearly verified that the proposed control method can accurately control the speed of a permanent magnet synchronous motor.

A Non-Linear Characteristics Modeling of High Frequency FL Lamp by Experimental Values (실험식을 이용한 고주파 형광램프의 비선형특성 모델링)

  • 함중걸;백수현
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.11 no.2
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    • pp.51-55
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    • 1997
  • The high frequency fluorescnet lighting systems are widely used because of their high luminous efficacy. However, the performance of the fluorescnet lamp at high frequency reveals significant changes depending upon operating frequency, lamp shape, lamp voltage and current while adapting either an electronic or an magnetic ballast. Therefore the matching between the fluorescent lamp and the ballast is the major concern in designing a lighting system. In this paper, high frequency characteristics of the FHF32W lamp is measured in a range of frequencies from 12kHz to 50kHz. And we presented a model of a fluorescnet lamp with non-linear impedance depending on the lamp current. Finally, after identifying the operating condition under negative imped¬ance behavior as lamp current changing, we proposed a method of choosing the optimal parameter of a high frequency fluorescnet lamp and the result is analyzed.

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Sinusoidal A Study on the gain Stability of the Feedback Linear Pulse Amplifiers for Fast Pulse Input (금속펄스 선형증폭기의 빠른 입력펄스에 대한 이득안정도에 관한 연구)

  • 이병선
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.11 no.3
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    • pp.1-14
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    • 1974
  • The gain stability of the nuclear pulse linear amplifiers with feedback for such a fast pulse input as the step voltage or the nuclear radiation detector pulse is analysed in detail. The expression is derived which describes the waveform at the anode circuit of the photomultiplier tube which is a part of the nuclear radiation detector. It is analysed and compared when the feedback amplifier has one and two time-constants. When these fast input pulse voltages are applied to the feedback amplifier, the effects of feedback in linearity and stability of the output voltage appear only after two or three rise-times of the amplifier, And it is proved that in order to reduce this limitation, the rise time of the feedback amplifier shou1d be less than the input pulse width. It is also shown that the above theory can be applied directly to the voltage-shunt feedback amplifier stages designed as the basic amplifier of the linear amplifier, and that the gain stability is more improved for the smaller input impedance of this amplifier stage.

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Fuzzy $H^{\infty}$ Controller Design for Uncertain Nonlinear Systems (불확실성을 갖는 비선형 시스템의 퍼지 $H^{\infty}$ 제어기 설계)

  • Lee, Kap-Rai;Jeung, Eun-Tae;Park, Hong-Bae
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.6
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    • pp.46-54
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    • 1998
  • This paper presents a method for designing robust fuzzy $H^{\infty}$ controllers which stabilize nonlinear systems with parameter uncertainty adn guarantee an induced $L_{2}$ norm bound constraint on disturbance attenuation for all admissible uncertainties. Takagi and Sugeno's fuzzy models with uncertainty are used as the model for the uncertain nonlinear systems. Fuzzy control systems utilize the concept of so-called parallel distributed compensation(PDC). Using a single quadratic Lyapunov function, the stability condition satisfying decay rate and disturbance attenuation condition for Takagi and Sugeno's fuzzy model with parameter uncertainty are discussed. A sufficient condition for the existence of robust fuzzy $H^{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMIs). Finally, design examples of robust fuzzy $H^{\infty}$ controllers for uncertain nonlinear systems are presented.

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A Study on Plate & Shell type Evaporator in HVAC System for Offshore Plant (해양플랜트 HVAC 시스템용 플레이트·쉘 타입 증발기에 관한 연구)

  • Park, Jae-Hong
    • Journal of the Korean Institute of Gas
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    • v.24 no.1
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    • pp.33-40
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    • 2020
  • Chiller systems which have better temperature stability than Direction expansion coils are often used as condensing units in HVAC systems for offshore plants. Large capacity compressors and electronic expansion valves in chiller systems are mostly imported, and the size of a chiller system depends on heat exchangers such as evaporators and condensers which are locally produced. Due to limited space in the offshore plants, shipyards are demanding manufacturers to make equipment compact. In this paper, a shell & tube heat exchanger, which is used as an evaporator in the conventional flooded chiller system, is replaced by a newly developed compact plate & shell heat exchanger. The main development process of the plate & shell heat exchanger is introduced, and its performances were experimentally evaluated with a real flooded chiller system, and the results are presented.

The Development of Electric Ballast for a Instant Start/Restart of Metalhalide Lamp (메탈핼라이드램프용 순시점등/재점등 전자식안정기 개발)

  • Kim, Su-Kyoung;Jang, Woo-Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.5
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    • pp.9-15
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    • 2004
  • The most shortcoming of metalhalide lamps is what the instant restarting cannot be realized when the arc tube is in the hot condition. The discharge starting voltage of arc tube in the hot condition is much higher than in the cold condition. Therefore it takes about five minutes to restart the metalhalide lamps, that is to say, it is possible to start when the pressure and the temperature are decreased. But, if the lamp is restarted in the hot condition, we must supply the high voltage pulse with 20[kV] at the both electrode of lamp. The proposed electronic ballast is consist of a electromagnetic interference(EMI) filter, a power factor correction(PFC) circuit, a flyback converter, a half-bridge inverter, and a high voltage igniter circuit. By this composition we can start/restart the lamp with the voltage 20[kV], even if the lamp is in the hot condition.

Development of the semi-active controlled variable damper system for passenger vehicles (승용차용 반능동형 가변댐퍼시스템의 개발)

  • 허승진;심정수;이광기;김홍석;황성호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1995.04a
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    • pp.45-50
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    • 1995
  • 본 연구에서는 기존에 널리 사용되고 있는 스카이훅 제어 알고리즘(skyhook control algorithm)[3]을 바탕으로 확장 개발된 모드 스카이훅 제어(mode skyhook control) 개념 및 주파수 감응식 제어(frequency dependent control)개념[4][5]을 실용화하기 위하여 응답속도가 20msec이하의 비교적 빠른 응답 속도를 갖는 전자기식 작동기 (electro-magnetic actuator)에 의해 가변되는 4단 반능동형 가변 댐퍼 시스템을 개발한 후, 다음과 같은 성능의 향상을 시험결과를 통하여 보이고자 한다. -저속에서의 승차감 향상과 고속에서의 주행 안정성 향상 -커브 주행 또는 급격한 핸들 작동시의 롤안정성 (rolling stability) 향상 -제동 및 급발진시의 차체 피칭 운동 방지 (anti-dive, anti-squat)

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Aging Behaviors of a Mg-Li-AI-Zr Alloy (Mg-Li-AI-Zr 합금의 시효거동)

  • Hyeon, Yang-Gi;Gang, Min-Cheol;Kim, Sun-Ho;Kim, In-Bae
    • Korean Journal of Materials Research
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    • v.6 no.9
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    • pp.925-930
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    • 1996
  • Zr이 0.03wt%함유된 Mg-8.14Li-3.93AI 합금의 시효거동을 미소경도와 미세조직의 변화, 열분석 등으로 조사하였다. Zr의 첨가로 인하여 3원계 Mg-8.23Li-4.02A에 비하여 조직이 미세화되었으며 모든 시효조건에서 경도값이 높게 나타났다. 열분석결과 발열피크는 준안정 석출상인 MgLi2AI($\theta$)의 석출과 $\theta$상에서 안정상인 AILi으로의 변화와 관련된 것이고, 흡열피크는 $\theta$와 AILi상의 재용해에 대응되는 것으로 판단되었다. 피크 경도값(103Hv)은 $\theta$의 석출이 완료되는 393K에서 0.5시간 시효시 나타났으며 피크 경도조건에서의 미세조건은 $\beta$기지에 $\theta$와 AILi상이 공존하고 있음을 투과식 전자현미경으로 확인하였다.

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The Indicator for Gas Interrupter Switcher (초고압 가스절연 차단기의 개폐 상태표시기)

  • Park, J.W.;Kim, J.S.;Kim, H.Y.;Bae, J.I.;Kim, J.K.;Park, C.K.
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.2538-2539
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    • 2000
  • 송배전 system에서 모선관리 및 운용에 있어 초고압 차단기는 매우 중요한 역할을 담당하고 있다. 선로의 운전상태와 차단기의 투입 상황 인식 및 확인은 필수요건이다. 이러한 차단기의 운전상태를 전자적인 신호성분을 검지하여 비접촉식 개폐 확인 unit가 필수적으로 대두되고 있다. 이 unit는 고신뢰성, 고안정성을 요구하며 정확한 표시가 필요하다. 송배전의 모든 System에 적용 가능하며 적용시 선로와 차단기의 운전 및 보수에 절대적인 안정성을 제공한다.

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