• 제목/요약/키워드: pulsed characteristics

검색결과 529건 처리시간 0.042초

충전전압 가변방식을 이용한 펄스형 Nd:YAG 레이저의 출력특성에 관한 연구 (The output characteristics of pulsed Nd:YAG laser with voltage variable capacitor-charging system)

  • 문동성;홍정환;송금영;송우정;김강호;김희제
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 하계학술대회 논문집 C
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    • pp.1703-1705
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    • 2001
  • The pulsed Nd:YAG laser is used widely for materials processing and medical instrument etc. It is important to control the laser energy in those fields using a pulsed Nd:YAG laser. In this paper, constant-frequency current resonant half-bridge inverter and Cockcroft-Walton circuit are used to charge the energy storage capacitor variably. This laser power supply is designed and fabricated which has no high-voltage transformer, less switching losses, compact size and capability in varying the laser output power. Also, the output characteristics of this Nd:YAG laser system are investigated. The tested results are described.

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PLD법에 의한 고집적 DRAM용 PLZT 박막의 레이저 에너지 밀도에 따른 특성 (Laser Energy Density Dependence Characteristics of PLZT Thin Films prepared by a PLD for Memory Device)

  • 마석범;장낙원;백동수;최형욱;박창엽
    • 한국전기전자재료학회논문지
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    • 제13권1호
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    • pp.60-65
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    • 2000
  • The structural and electrical characteristics of PLZT thin films fabricated onto Pt/Ti/SiO\ulcorner/Si substrates by a pulsed laser deposition were investigated to develop the high dielectric thin films were fabricated with different energy density by pulsed laser deposition. This PLZT thin films of 5000 thickness were crystallized at 600 $^{\circ}C$, 200 mTorr O\ulcorner pressure for 2 J/$\textrm{cm}^2$ laser energy density, the arain structure was transformed from planar to columnar grain. It was clearly noted from the SEM observations that oxygen pressured laser powers affect microstructures of the PLZT thin films. 14/50/50 PLZT this film showed a maximum dielectric constant value of $\varepsilon$\ulcorner=1289.9. P-E hysteresis loop of 14/50/50 PLZT thin film was flim ferro-electric. Leakage current density of 14/50/50 PLZT thin film was 10\ulcorner A/$\textrm{cm}^2$.

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펄스 Nd:YAG 레이저에 의한 브라운관 부품의 용접시 빔의 출력특성과 광학변수 (Characteristics of Output Energy and Optical Parameters in Welding of Braun Tubes by Pulsed Nd:YAG Laser)

  • 김종도;하승협
    • 한국레이저가공학회지
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    • 제8권1호
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    • pp.27-37
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    • 2005
  • During laser spot welding of the braun tube electron gun, phenomena such as serious spattering and oxidative reaction, etc. were occurred. The spatter occurred from weld pool affects the braun tube, namely it blocks up a very small hole on the shadow mask and causes short circuit between two poles of the electron gun. We guessed that high power density and oxidative reaction are main sources of these problems. So, we studied to prevent and to reduce spatter occurring in spot welding of the braun tube electron gun using pulsed Nd:YAG laser. The characteristics of laser output power was estimated, and the loss of laser energy by optical parameter and spatter was measured by powermeter. The effects of welding parameters, laser defocused distance and incident angle, were investigated on the shape and penetration depth of the laser welded bead in flare and flange joints. From these results, the laser peak power was a major factor to control penetration depth and to occur spatter. It was found that the losses of laser energy by optic parameter and sticked spatter affect seriously laser weldability of thin sheets.

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SMPS 방식의 고반복 펄스형 $CO_2$레이저의 출력특성 최적화 (The Optimization of Output Characteristics with High Repetition Rate Pulsed $CO_2$ Laser Using SMPS)

  • 이동훈;정현주;김도완;김휘영;김희제;조정수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1999년도 하계학술대회 논문집 E
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    • pp.2192-2194
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    • 1999
  • In this study, We have accomplished a new approach to develope a cheap and compact pulsed $CO_2$ laser system. We used a fast SCR as switching device instead of a thyatron in the pulsed power supply. Using the Pulse transformer, energy in the condenser is tranferred to the secondary, electrodes of discharge tube, from the primary. An axial and water cooled type was adopted as the laser cavity. The laser performance characteristics as various parameters, such as gas pressure and pulse repetition rate, have been investigated. As a result, the maxium laser output was 12.3[W] at a pulse repetition rate of 120[pps] and a filling pressure of 12[Torr].

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Observations of Pulsed Bi-polar Discharges in Saline Solutions with Pin to Plate Electrodes

  • Shin, Bhum Jae;Seo, Jeong-Hyun;Collins, George J.
    • Journal of Electrical Engineering and Technology
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    • 제13권5호
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    • pp.2011-2016
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    • 2018
  • In this study, we have been investigated pin to plate pulsed bi-polar discharges in saline solutions, where bubble generation occurs. We integrate basic I-V-t electrical characteristics with the ICCD shadowgraph images, and finally instant and time averaged I-V waveforms. We observed that the bubble formation phase dynamics is quite different corresponding to the polarity applied to the pin electrode. When the pin electrode is a cathode, the bubble tends to be periodically detached from the pin electrode and the numerous tiny voltage spikes occur related to the electron emission from a pin cathode casing via, we judge from, direct dissociation of water molecules by energetic electrons. On the contrary, the bubble tends to stick to the pin electrode, when the pin electrode is anode; the bubble grows in size throughout the pulse duration. The dynamic electrical characteristics relative to the applied polarity of a pin electrode are presented and discussed by analysis of time averaged I-V waveforms.

EMTDC를 이용한 8.5 MVA급 Magnetic Power Supply의 전력공급 시스템 분석 (Analysis of Power Supply System for 8.5 MVA Magnetic Power Supply Using EI)

  • 정응후;노의철;김인동;최정완
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2002년도 하계학술대회 논문집 B
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    • pp.1114-1116
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    • 2002
  • The characteristics of voltage drop and THD for parallel operating 11 PCRs (Phase Controlled Rectifiers) are analysed. The PCRs are used to drive high current (1.6 kA ${\sim}$ 3.7 kADC) electromagnetic coils for electromagnets. All the PCRs operate simultaneously in pulsed mode, and the pulse shot occurs every 150 seconds. During the pulse operation the PCR output current ramps up for 4 seconds, and then keeps flat top state for 2 seconds, and finally ramps down for 4 seconds. For the flat top mode a severe voltage drop and distortion appear in the power system because transformers for the PCRs are designed considering pulsed mode operation. It is expected that the analysis method can be applied to improve the system performance including power factor and design of high power pulsed mode operating power supply systems.

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펄스 코로나 방전 반응기를 이용한 NOX 제거 효율 및 입자 성장 분석 (Analysis on NOX Removal Efficiencies and Particle Growth Using Pulsed Corona Discharge Reactor)

  • 박정환;김동주;김교선
    • 산업기술연구
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    • 제21권B호
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    • pp.155-161
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    • 2001
  • In this study, we analyzed the $NO_X$ removal efficiency and particle size distribution by the pulsed corona discharge process and investigated the effect of several process variables. The NO removal efficiencies and the particle characteristics were measured and analyzed as the function of initial concentrations of NO, $H_2O$, and $NH_3$, applied voltage, pulse frequency and residence time. As the frequency of applied voltage increases, or as the applied voltage increases or as the residence time increases, the NO removal efficiency increases. The change of initial $NH_3$ and $H_2O$ concentrations do not affect the NO removal efficiency significantly. The particle concentration and size increases with the increases of initial NO concentration, residence time and applied voltage.

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Theoretical Modeling of Pulsed Plasma Thruster Performance with Teflon Ablation

  • Cho, Mingyoung;Sung, Hong-Gye
    • International Journal of Aeronautical and Space Sciences
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    • 제18권1호
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    • pp.138-143
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    • 2017
  • A performance analysis for a pulsed plasma thruster(PPT) has been conducted to predict the thrust and current change. Two models were implemented - a one-dimensional lumped circuit analysis model and the Teflon ablation model provided by Michael Keidar. The circuit model incorporating resistance and inductance models was adapted to predict the magnitude of the discharge current. Numerical simulations like current discharge rates with different voltages were reasonably well compared with experimental data. The effects of Teflon ablation on thruster characteristics were investigated.

PLD를 이용한 ZnO 박막의 발광에 관한 연구 (Photoluminescence characteristics of ZnO thin films by Pulsed laser deposition)

  • 김재홍;이경철;이천
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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    • pp.1030-1033
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    • 2002
  • ZnO thin films on (100)p-type silicon substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YGA laser with a wavelength of 266nm. The influence of the deposition parameters, such as oxygen pressure, substrate temperature and laser energy density variation on the properties of the grown film, was studied. The experiments were performed for substrate temperatures in the range of $200{\sim}500^{\circ}C$ and oxygen pressure in the range of $10^{-2}{\sim}10^2mTorr$. We investigated the structural, morphological and optical properties of ZnO thin films using X-ray diffraction(XRD), atomic force microscopy(AFM), photoluminescence(PL).

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펄스 코로나 농약산포장치의 분무대전 특성 (Pulsed Corona Charging Characteristics of Aqueous Pesticide Spray)

  • 문재덕;이운태;배창환;권남열
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제52권9호
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    • pp.388-394
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    • 2003
  • Many toxic pesticides as aqueous-base sprays are dispensed for protection of food crops from pests into farm fields. When dispensed with conventional nozzles, a large portion of the spray is often lost by airborne drifts of droplets away and lack of deposition onto the plants due to rapid gravitational settling of droplets to the soil beneath. And target deposition efficiencies poorer than 20% are often encountered in agricultural pesticides. An electrostatic spraying technology offers a very favorable means to increasing pesticides droplets deposition onto biological surfaces of living crops. In this paper a corona type spray nozzle, utilizing a set of corona charging devices and a pulsed droplet-charging voltage applied, has been proposed and tested its potential experimentally. As a result, it exhibits a large current deposition of aqueous pesticide sprays on the sensing target, which, however, promise to be as one of the effective electrostatic spraying nozzle.