• Title/Summary/Keyword: V-128

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A Design of LC-tuned Sinusoidal VCOs Using OTA-C Active Inductors

  • Chung, Won-Sup;Son, Sang-Hee
    • Journal of IKEEE
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    • v.11 no.3
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    • pp.122-128
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    • 2007
  • Sinusoidal voltage-controlled oscillators (VCOs) based on Colpitts and Hartley oscillators are presented. They consist of a LC parallel-tuned circuit connected in a negative-feedback loop with an OTA-R amplifier and two diode limiters, where the inductor is simulated one realized with temperature-stable linear operational transconductance amplifiers (OTAs) and a grounded capacitor. Prototype VCOs are built with discrete components. The Colpitts VCO exhibits less than 1% nonlinearity in its current-to-frequency transfer characteristic from 4.2 to 21.7 MHz and ${\pm}$95 ppm/$^{\circ}C$ temperature drift of frequency over 0 to $70^{\circ}C$. The total harmonic distortion (THD) is as low as 2.92% with a peak-to-peak amplitude of 0.7 V for a frequency-tuning range of 10.8-32 MHz. The Hartley VCO has the temperature drift and THD of two times higher than those of the Colpitts VCO.

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Implementation of fiber-optic temperature sensor system base on optical absorption device (광흡수 소자를 이용한 광온도 센서 시스템의 구현)

  • 김영수;김요희
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.9
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    • pp.128-134
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    • 1995
  • A fiber-optic temperature sensor utilizing an optical absorption device (InP) was fabricated. The spectrum of transmitted light through an InP device was obtained at the three temperatures(249 K, 369 K). A stabilized LED(light emmiting diode) driver, photoreceiver, and signal proocessing electronics were designed. An intensity referencing technique was adopted in order to minimize the fluctuation of output signal due to external pertubation of the transmitting optical fiber. The optical absorption edge of the InP device moves to longer wavelength at a rate of 0.42 nm / K, and energy gap of InP is 1.35 eV at room temperature. From these results, it is concluded that the InP device has temperature dynamic range of 300 K with LED of center wavelength of 940nm and spectral width of 50nm. The designed fiber-optic temperature sensor system showed good linearity within the temperature range from -30$^{\circ}C$ to + 150$^{\circ}C$.

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Annealing-temperature Dependent Characteristics of PLZT Thin Films on ITO Coated Glass (ITO 기판에 제작된 PLZT 박막의 소성온도에 따른 특성)

  • Choi, Hyung-Wook;Jang, Nak-Won;Park, Chang-Yub
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.2
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    • pp.128-132
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    • 1998
  • 2/65/35 PLZT stock solution prepared by Sol-Gel processing was spin-coated on ITO coated glass and annealed by RTA(Rapid Thermal Annealing). The crystal structure of films was reported based on the observation of crystallization process and microstructure of the film fabricated at different fabrication condition. Films were crystallized into rhombohedral structure by annealing at $750^{\circ}C$ for 5 min. As the annealing temperature increased, the size of rosette structure of the films was grown up from $2.4{\mu}m$ to $15{\mu}m$, dielectric constant was increased, coercive field was decreased 33.82 kV/cm, remnant polarization was increased to 39.84 ${\mu}C/cm^2$ and Optical transmittance was decreased.

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7-Level Medium Voltage Inverter System with PWM Converter for Regenerating Operation (회생능력을 가지는 7-레벨 고압인버터 시스템)

  • Kim Kwang-Seob;Bang Sang-Suk;Kwon Byung-Ki;Moon Sang-Ho;Yang Byung-Hun;Lee Myung-Jun;Choi Chang-Ho
    • Proceedings of the KIPE Conference
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    • 2006.06a
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    • pp.128-130
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    • 2006
  • We introduce 2[MVA] 3300[V] 7-level voltage source inverter system developed by POSCON and describe the main characteristics of inverter system i.e. PWM converter, H-bridge power module, phase shifted carrier PWM The PWM converter is a three-phase boost converter, which operates in a 4-quadrant and in a nearly unit displacement power factor. Experimental waveforms are also presented to verify the proposed method and performance of the developed system.

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A Study on Characteristic of Ceramic Tube for Ozone Generation (오존발생용 세라믹 방전관 특성에 관한 연구)

  • Cho, Kook-Hee;Kim, Young-Bae;Lee, Hong-Sik
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1724-1726
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    • 2002
  • A novel ozonizer has been developed using a high-frequency surface discharge and a high purity alumina ceramic as its dielectric component. A thin ceramic layer, cylindrical in form, is adhered by a film-like induction electrode. An ac exciting voltage of frequency to 0.6 kHz from 1.0 kHz and $6{\sim}9kV$ peak-to-peak is applied between the electrodes to produce a stable high-frequency silent discharge for generation of ozone. A substantial reduction of the exciting voltage is also enabled by using a thin alumina ceramic layer. As a result, the ozonizer can easily produce ozone concentration($128g/m^2$ for oxygen) and power efficiency(360g/kWh for oxygen) without using a special enrichment means.

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Development of a Portable Cardiac Event Recorder (휴대용 심전도 이벤트 기록기 개발)

  • Chun, H.G.;Kim, H.C.;Lee, C.Y.;Kim, I.Y.
    • Proceedings of the KOSOMBE Conference
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    • v.1998 no.11
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    • pp.187-188
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    • 1998
  • A low cost, low power, portable cardiac event recorder as a tether-free biological signal processor was developed. Dual channel ECG signals are sampled at 128Hz in 12 bits resolution. Sampled data are continuously recorded in a circular buffer. If event button is pressed, 2 minutes data before and after the event are recorded in 512 Kbyte SRAM. Total 11 events can be recorded. Data can be transferred to PC through RS-232 protocol. It operates for two months by a half AA size 3.6V Lithium battery. The system size is $55\times55\times13[mm^3]$.

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A Study on Seasonal Changes of Lakes Water Quality Characteristics -Based on experiments in the SEOSAN area- (호수의 계절별 수질 특성에 관한 연구 - 서산 지역을 중심으로 -)

  • 이영신
    • Journal of environmental and Sanitary engineering
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    • v.13 no.3
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    • pp.128-132
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    • 1998
  • In this study, water quality characteristics of lakes in the Seosan area are analyzed. Components water quality were analysed at 10 sampled points in each lakes, and the results were evaluated for seasonal variation. It was found that water quality was over II~III class. Most of lakes in the Seosan area which implies that are suitable as the maintenance water. The concenturation of T-N, T-P was observed IV~V class during all seasons. Particularly, T-N concenturation peaks in spring, while was lowered in other seasons. In the lake, high concenturation of T-N, T-P bring about Eutrophication when algae was growth causing various physico-chemical changes in the water. It is suggested that the water quality management strategies need to be applied for each lake.

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Novel Organic Sensitizers with a Quinoline Unit for Efficient Dye-sensitized Solar Cells

  • Choi, Hye-Ju;Choi, Hyun-Bong;Paek, Sang-Hyun;Song, Ki-Hyung;Kang, Moon-Sung;Ko, Jae-Jung
    • Bulletin of the Korean Chemical Society
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    • v.31 no.1
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    • pp.125-132
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    • 2010
  • Three organic sensitizers, JK-128, JK-129, and JK-130 containing quinoline unit are designed and synthesized. Under standard global AM 1.5 solar condition, the JK-130 sensitized solar cell gave a short circuit photocurrent density of 11.52 mA $cm^{-2}$, an open circuit voltage of 0.70 V, and a fill factor of 0.75, corresponding to an overall conversion efficiency of 6.07%. We found that the $\eta$ of JK-130 was higher than those of other two cells due to the higher photocurrent. The higher $J_{sc}$ value is attributed to the broad and intense absorption spectrum of JK-130.

Effects of Rapid Thermal Anneal on the Magnetoresistive Properties of Magnetic Tunnel Junction

  • Lee, K.I.;Lee, J.H.;K. Rhie;J.G. Ha;K.H. Shin
    • Journal of Magnetics
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    • v.6 no.4
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    • pp.126-128
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    • 2001
  • The effect of rapid thermal anneal (RTA) has been investigated on the properties of an FeMn exchange-biased magnetic tunnel junction (MTJ) using magnetoresistance and I-V measurements and transmission electron microscopy (TEM). The tunneling magnetoresistance (TMR) in an as-grown MTJ is found to be ∼27%, while the TMR in MTJs annealed by RTA increases with annealing temperature up to 300$\^{C}$, reaching ∼46%. A TEM image reveals a structural change in the interface of A1$_2$O$_3$layer for the MTJ annealed by RTA at 300$\^{C}$. The oxide barrier parameters are found to vary abruptly with annealing time within a few ten seconds. Our results demonstrate that the present RTA enhances the magnetoresistive properties of MTJs.

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A High-Speed 2-Parallel Radix-$2^4$ FFT Processor for MB-OFDM UWB Systems (MB-OFDM UWB 통신 시스템을 위한 고속 2-Parallel Radix-$2^4$ FFT 프로세서의 설계)

  • Lee, Jee-Sung;Lee, Han-Ho
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.533-534
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    • 2006
  • This paper presents the architecture design of a high-speed, low-complexity 128-point radix-$2^4$ FFT processor for ultra-wideband (UWB) systems. The proposed high-speed, low-complexity FFT architecture can provide a higher throughput rate and low hardware complexity by using 2-parallel data-path scheme and single-path delay-feedback (SDF) structure. This paper presents the key ideas applied to the design of high-speed, low-complexity FFT processor, especially that for achieving high throughput rate and reducing hardware complexity. The proposed FFT processor has been designed and implemented with the 0.18-m CMOS technology in a supply voltage of 1.8 V. The throughput rate of proposed FFT processor is up to 1 Gsample/s while it requires much smaller hardware complexity.

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