• Title/Summary/Keyword: N-current

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A New Injection Method of Harmonic Compensation Current by Active AC Power Filter (능동형 교류 전력 필터에 의한 고조파 보상전류의 새로운 주입방식)

  • 박민호;최규하
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.34 no.9
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    • pp.361-367
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    • 1985
  • A new injection method is proposed for active power filters to eliminate AC harmonics in ac input current of nonlinear loads such as rectifiers. By injecting the PWM current determined by the proposed injection method, all the harmonics up to order nn can be eliminated to exactly zero. This PWM injection current can be generated by sampling total harmonic wave at the rate of M and the sampled values are converted into the proposed PWM wave with N pulse-width variables and adjustable current magnitude Im. These variables are deetermined by solving a set of N nonlinear harmonic equations and the harmonic-elimination characteristics of the new injection are investigated through digital computer sinmulation. Also by comparing between the simulated results and the ones synthesized by data stored in EPROM, the possibility of the suggested injection method can be shown.

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Electrical Characteristics of Metal/n-InGaAs Schottky Contacts Formed at Low Temperature

  • 이홍주
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.5
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    • pp.365-370
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    • 2000
  • Schottky contacts on n-In$\_$0.53//Ga$\_$0.47//As have been made by metal deposition on substrates cooled to a temperature of 77K. The current-voltage and capacitance-voltage characteristics showed that the Schottky diodes formed at low temperature had a much improved barrier height compared to those formed at room temperature. The Schottky barrier height ø$\_$B/ was found to be increased from 0.2eV to 0.6eV with Ag metal. The saturation current density of the low temperature diode was about 4 orders smaller than for the room temperature diode. A current transport mechanism dominated by thermionic emission over the barrier for the low temperature diode was found from current-voltage-temperature measurement. Deep level transient spectroscopy studies exhibited a bulk electron trap at E$\_$c/-0.23eV. The low temperature process appears to reduce metal induced surface damage and may form an MIS (metal-insulator-semiconductor)-like structure at the interface.

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Design of Rogowski coil to improve of current measurement sensitivity (전류측정감도 개선을 위한 로고우스키 코일의 설계)

  • Park, J. N.;Lee, C.;Jang, Y. M.;Kang, S. H.;Lim, K. J.;Na, D. H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.609-612
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    • 2001
  • Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents, and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore, geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error wa examined as well. n the results, the source of error was associated with coil designs, i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

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Analysis of CRUD Flake Applied to Abnormal High Beam Current by Shielded-EPMA

  • Jung, Y.H.;Baik, S.J.;Ahn, S.B.
    • Corrosion Science and Technology
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    • v.17 no.6
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    • pp.265-271
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    • 2018
  • CRUD specimens, scraped from twice-burned fuel cladding in the Korean Nuclear Power Plant, were analyzed using Shielded-EPMA. The principal elements of the CRUD were identified as Ni and Fe, at an approximate ratio of 1.3 Ni/Fe. To investigate the morphology and composition of the pure metallic materials in the CRUD, coolant impurities must be removed. This can be accomplished by increasing the EPMA current to an abnormally high intensity until the impurities are melted. Normally, EPMA applications are performed at conditions of 20 kV voltage and 20 nA current. But in our study, the applied current was increased up to 1200 nA, over time increments ranging from 5 to 30 seconds. This technique was performed by opening an adjustable aperture for the gun alignment. Results showed impurities contained in the CRUD material disappeared and pure metal materials, e.g., Ni and Fe, remained. This method presents an innovative way to analyze CRUD.

Resonance Frequency and Bandwidth of the Negative/Positive nth Mode of a Composite Right-/Left-Handed Transmission Line

  • Kim, Seong-Jung;Lee, Jeong-Hae
    • Journal of electromagnetic engineering and science
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    • v.18 no.1
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    • pp.1-6
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    • 2018
  • In this study, the analytic expression for the positive/negative $n^{th}-Mode$ resonance frequency of an N unit cell composite right-/lefthanded (CRLH) transmission line is derived. To explain the resonance mechanism of the $n^{th}$ mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative $n^{th}$ resonance modes have n times current variations, but their phase difference is $180^{\circ}$ as expected. Moreover, the positive $n^{th}$ resonance occurs at a high frequency, whereas the negative $n^{th}$ resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.

A Study on Developement of CuN/Cu/CuN Electrode Material for PDP (PDP용 CuN/Cu/CuN 전극재료의 개발에 관한 연구)

  • Cho, J.S.;Park, C.H.;Sung, Y.M.;Jeong, S.S.;Seok, B.Y.;Ryu, J.Y.;Kim, J.H.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1572-1575
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    • 1996
  • A new type $Cu_{x}N/Cu/Cu_{x}N$ thin film electrode material with high adhesion to glass was developed by the dc reactive planar magnetron sputtering system for the PDP(Plasma Display Panel). The adhesive force of the $Cu_{x}N$ thin film was in the range of $20{\sim}40(N)$ under the conditions of the $N_2$ partial pressure of 15%, discharge current of 70mA, discharge voltage of 450V and substrate bias voltage of -100V. The adhesive force was depended on the $N_2$ partial pressure, discharge current and substrate bias voltage.

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$RuO_2$ Related Schottky contact for GaN/AlGaN device

  • Jung, Byung-Kwon;Kim, Jung-Kyu;Lee, Jung-Hee;Hahm, Sung-Ho
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • 2002.11a
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    • pp.85-90
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    • 2002
  • $RuO_2$/GaN and related contacts were investigated for Schottky contacts in GaN-Based optical and electronic devices. We demonstrated that an $RuO_2$ film forms a stable Schottky contact on a GaN layer with a barrier height (${\Phi}_B$) of 1.46 eV and transmittance of 70% in the visible and near UV region. $RuO_2$/GaN Schottky diode showed a breakdown at over -50V and leakage current of only 0.3 nA at -5V. The $RuO_2$/GaN Schottky type photodetector had the UV/Visible rejection ratio of over $10^5$ and the responsivity of 0.23 A/W at 330 nm. The $RuO_2$ gate AlGaN/GaN EFET exhibited high drain current ($I_d$) of 689.3 mA/mm and high transconductance ($g_m$) of 197.4 mS/mm. Cut-Off frequency ($f_t$) and maximum operating frequency ($f_{max}$) were measured as 27.0 GHz and 45.5 GHz, respectively.

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A Study on Joining Method of BSCCO(223) Multifilamentary Tape (BSCCO(2223) 다심 초전도 선재의 접합공정 연구)

  • 김정호;김규태;주진호;나완수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.6
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    • pp.511-517
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    • 2001
  • We evaluated the electrical properties of 37 multifilamentary jointed tapes processed by superconducting joint. In the superconducting joining method, a lap-joint was used. Tapes were selectively etched, and exposed superconducting cores of the two tapes were brought into contact with each other and then only the joined region was uniaxially pressed in the range of 1,000 to 2,50 MPa. The critical current ratio(CCR) and n-value of the jointed tape were evaluated as a function of uniaxial pressure and number of step in the contacting region. It was observed that the CCR was dependent on the number of step, but almost independent of uniaxial pressure. The highest critical current ratio and n-value were obtained to be 58% and 26%, respectively, for the jointed tape to the tape itself.

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High-performance InGaN/GaN-based Light-emitting Diodes Using Advanced Technical Approaches

  • Jang, Ja-Soon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.108-108
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    • 2012
  • High-performance GaN-based light emitting diodes (LEDs) with high efficiency and excellent reliability have been of technological importance forapplications in full color display, automotive lighting, and solid state lighting. To realize high-performance and excellent-reliability LEDs, various technologies such as surface texturing, transparent conducting oxide, surface Plasmon, highly p-conduction layer, current blocking layer, photon-enhanced layer, and nanostructures have been extensively investigated. Among them, advanced core technologies based on how to suppress surface leakage and current crowding, how to enhance current injection efficiency and output power, and how to resist electrostatic damage will be displayed and discussed using our reported and preliminary results. New approaches like integrated LEDs will be also introduced and discussed.

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Physics and current density-voltage characteristics of $a-Si_{1-x}Ge_x:H$ alloy p-i-n solar cells ($a-Si_{1-x}Ge_x:H$ 화합물(化合物) p-i-n 태양전지(太陽電池)의 물리(物理) 및 전류밀도(電流密度)-전압(電壓) 특성(特性))

  • Kwon, Young-Shik
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1435-1438
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    • 1994
  • The effects of Ge composition variation in $a-Si_{1-x}Ge_x:H$ alloy p-i-n solar cells on the physical properties and current density-voltage characteristics are analyzed by a new simulation modelling based on the update published experimental datas. The simulation modelling includes newly formulated density of gap density spectrum corresponding to Ge composition variation and utilizes the newly derived generation rate formulars which include the reflection coefficients and can apply to multijunction structures as well as single junction structure. The effects in $a-Si_{1-x}Ge_x:H$ single junction are analyzed through the efficiency, fill factor, open circuit voltage, short circuit current density, free carriers, trap carriers, electric field, generation rate and recombination rate. Based on the results analyzed in single junction structure, the applications to multiple junction structures are discussed and the optimal conditions reaching to a high performance are investigated.

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