• Journal of the Microelectronics and Packaging Society
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• v.3 no.2
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• pp.51-56
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• 1996

각종 통신기기의 주파수 합성기 등에 광범위하게 응용되고 있는 전압제어 발진기에 서 캐리어 대 잡음비(C/N비:Carrier noise Ratio)특성이 매우 중요하다. 특히 휴대용 단말기 에 쓰이는 소형 저소비전려의 VCO는 위상 잡음의 억제가 필수적이다. VCO의 C/N비 특성 은 공진회로의 선택도 Q와 능동소자의 각종 파라미터들 그리고 발전전력과 밀접한 관계가 있다. 본 논문에서는 CAD를 이용하여 우수한 C/N비를 갖는 900MHz대 VCO의 최적화 설 계방버을 제시하고 그 결과를 기초로 우수한 저잡은 VCO를 실현하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.117-117
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• 2013

레이저 레이더용 시력안전파장대 고출력 광펄스 생성을 위한 광원으로 MOPA 구도로 광섬유 레이저를 제작 하였다. MOPA 기반 펄스 광섬유 레이저는시력 안정 파장대인 1,550 nm 대역 파장을 갖고 펄스폭이 2 ns 이하이며 반복률이 30~240 kHz 가변 가능하다. 광섬유 증폭단에서 1단 증폭기는 저잡음용 코어 펌핑 방식의 증폭기로 구현하였으며, 2단 증폭기는 중출력 증폭기로 코어 펌핑구조에 후방향 펌핑 구도로 설계하였다. 3단 증폭기는 최종목표인 2ns 이하의 펄스 폭 및 25 kWp 이상의 첨두출력을 달성하기 위하여 클래딩 펌핑 방식의 고출력 광증폭기로 구현하였다.

• Journal of IKEEE
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• v.22 no.2
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• pp.518-521
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• 2018

IVN (in-vehicle network) connects various electronic modules in the vehicles. It requires real-time, low noise, high reliability, and high flexibility. It includes CAN (controller area network), CAN-FD (CAN flexible data rate), FlexRay, LIN (local interconnect network), SENT (single edge nibble transmission), and PSI5 (peripheral sensor interface 5). In this paper, their operation priciples, target applications, and pros and cons are explained.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.1
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• pp.7-12
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• 1984

In this paper, the authors applied the method of hydrogen chloride gettering oxidation to fabricate the low noise bipolar transistor. The results of measurements of the effect of guttering on the variation of flicker noise spectral intensity for variable HCI concentrations indicate that flicker noise in bipolar than-sistor is dependent on the surface condition and that the gettering in a mixture of 2% HCI in oxidation produced the optimal results in the fabrication of the low noise device. In addition, it was also noted that the PSG layer formed by the emitter source (phosphorus) did not have so much guttering effect as in the process with HCl getterinng.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.443-447
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• 2003

In this work. using 0.2 GaAs modulation doped FET(MODFET), a high performance DBS downconverter MMIC was developed for direct broadcasting satellite (DBS) application. Without LNA, the downconverter MMIC showed a very low noise of 4.8 dB, which is lower by 3 dB than conventional ones. A low LO power of -10 dBm was required for the normal DBS operation of the downconverter MMIC. which reduced the power consumption via a removal of LO amplifier on MMIC. It required only a low power consumption of 175 mW, which is lower than 70 percent of conventional ones. The LO leakage power at IF output was suppressed to a lower level than 30 dBm, which removes a bulky LO rejection filter on a board. The fabricated chip, which include a mixer, If amplifiers. LO rejection filter, and active balun, exhibited a small size of $0.84{\times}0.9\textrm{mm}^2$.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.764-766
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• 1998

An evaluation method for oxygen permeable characteristics of the membrane covering to each cathode of multiple cathode - single anode type dissolved oxygen sensor, which has high reproducibility and is capable of measuring multiple components in solutions. For this purpose, a measuring circuit for the multiple cathode type DO sensor was designed to lower the noise signal by adapting a digital LPF to readout the sensor output accurately. Digital LPF is designed by setting up the transfer function to set the cutoff frequency to 10Hz, and the transfer function is programmed by C language, and then the filtering characteristics are evaluated with the simulation and experiments. Using this LPF added measuring circuit for the multiple cathode type DO sensor, we have obtained the calibration factor for each cathode to calibrate the variation of the output signals. The calibration factor was obtained by measuring the sensor output signal followed by oxygen partial pressure, using the same oxygen permeable membrane at each cathode of the multiple cathode type DO sensor.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.315-322
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• 1998

Power conversion system must increase switching frequency in order to achieve small size, light weight and low noise. However, the switches of converter are subject to high switching power losses and switching stresses. As a result, the power system has a lower efficiency. In this paper, the authors propose an AC-DC boost converter of high efficiency by partial resonant switching mode. The switching devices in the proposed circuit are operated with soft switching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. Besides, by regenerating energy, that is charged in a loss less snubber condenser of a snubber adopted to a common circuit, toward an input source part, this circuit can get increased efficiency. as merit. The result is that the switching loss is very low, the efficiency and power factor of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.334-338
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• 2009

Recently, with increasing demand for flat-panel display product, methods for large area patterning are required. TIR (total internal reflection) holographic photo-lithography isstudied as one of the methods of large area lithography. In conventional TIR holography, light sources for hologram recording and image reconstruction are coherent beams such as laser beams. If the image is reconstructed with an incoherent light source such a UV lamp, the image noise from the coherence of light will be reduced and the UV lamp will be a better light source for large area exposure. We analyzed the effect of spectral bandwidth and angular bandwidth of the light source in image reconstruction and verified image blurring with experiments. For large area patterning which has micro-scale line width, it is expected that TIR holographic photo lithography by UV lamp will become a low-noise and low-priced technique.