• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.28-32
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• 2010

We demonstrate binary spectral phase coded waveform discrimination at 10 GHz for narrow band optical code-division multiple-access (NB-OCDMA) via direct electrical detection without using any optical hard-limiter. Only 9 phase-locked, 10 GHz spaced, spectral lines within a 100 GHz spectral window are used for the phase coding. Considerably high contrast ratio of 5 between signal and multiuser access interference noise can be achieved for $4{\times}10\;G\;pulse/sec$ timing coordinated OCDMA at a simple electrical receiver with 50 GHz bandwidth.

• 전기학회논문지
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• 제56권11호
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• pp.2004-2009
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• 2007

A new high-speed drive method for the plasma display panel is proposed. In this method, the address period is inserted for the rest period of the sustain pulses and the priming pulse is applied on the entire panel at the same time overlapping with the sustain period. The ramp shaped priming pulse can be made with a simple drive circuit in this technology and the stable sustain discharge can be induced even by a narrow scan pulse in help of the space charge generated from the address discharge. From the experiments, it is ascertained that the priming pulse hardly influences the sustain discharge. Moreover, the voltage margin of the sustain discharge is almost constant though that of the address discharge broadens with narrowing the scan pulse width. And, if the time interval between the scan pulse and the sustain pulse is within $6{\mu}s$, the voltage margin of the address and the sustain discharges are unaffected though the applied position of the scan pulse is changed. High-speed driving with the address pulse of $0.7{\mu}s$ width was achieved and the address voltage margin of 20V and the sustain voltage margin of 10V were obtained.

• 한국통신학회논문지
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• 제24권12B호
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• pp.2292-2297
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• 1999

기상레이다에 수신되는 도플러 스펙트럼의 약 25%는 비대칭 스펙트럼, 즉 skewed spectrum 인 것으로 알려지고 있다. 그러나 기상정보의 추출을 위하여 가장 널리 쓰이고 있으며 효율적인 것으로 알려진 기존의 펄스페어 추정방법은 도플러 스펙트럼이 대칭형 또는 매우 좁은 주파수 대역을 갖는다는 가정을 전제로 하고 있다. 따라서 본 논문에서는 이와 같은 가정이 만족되지 않을 경우 기상레이다에서의 스펙트럼 모멘트들의 추정치에 상당한 편향오차가 발생할 수 있음을 정량적으로 분석하였다. 또한 이러한 편향오차가 상대적으로 심각한 평균 도플러 주파수 추정치의 정확도를 향상시키기 위하여 다중 펄스페어 추정기법을 제안하였다. 제안한 방법을 적용할 경우 편향오차가 현저히 줄어들을 확인할 수 있었다.

• 한국전기전자재료학회논문지
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• 제31권1호
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• pp.1-5
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• 2018

This study analyzed the change of electrical characteristics of a photocoupler when a narrow-band electromagnetic wave was combined with the photocoupler. A magnetron (3 kW, 2.45 GHz) was used as the narrow-band electromagnetic source. The EUT was Photocoupler (6N139) and the input signal was divided into two types: a square pulse and the second signal is 0 V. The malfunction of the photocoupler was confirmed by monitoring the variation in the output voltage of the photocoupler. As a result of the experiment, changes in the malfunctioning was observed as the electric field was increased. There are three types of malfunction modes: delay, output voltage off, and fluctuation. Bit errors were analyzed to verify the electrical characteristics of the photocoupler by narrow-band electromagnetic waves. The result of this study can be used as basic data for the effect analysis of photocoupler protection and impact analysis of high-power electromagnetic waves.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.211-218
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• 1998

The purpose of this study is to investigate the reduction rate of NOX according to several parameters(NOX concentration, the flow rate of gas, the additional amount of C2H4, input voltage, input frequency and so in) when NOX is reduced by using PPCP(Pulse-induced Plasma Chemical Process). PPCP is based on the plasma-chemical technology, which induces narrow voltage pulses to binary electrode structure.

• 비파괴검사학회지
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• 제14권3호
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• pp.185-193
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• 1994

범용의 초음파탐상장치에서는 탐촉자를 구동하기 위하여 높은 전압의 좁은 펄스를 사용하는데, 이 펄스의 평균 출력에는 제한이 따른다. 과도하게 높은 전압은 탐촉자를 파괴시키고, 지나치게 긴 펄스는 분해능을 감소시킨다. 긴 폭의 의사렌덤신호를 사용한 펄스압축은 상호관계를 이용하여 분해능을 감소시키지 않고 신호대 잡음비를 개선할 수 있다. 본 연구에서는 Golay 코드를 사용한 초음파펄스압축법을 개발하였다. 이론적으로 펄스압축에서의 신호 특성 및 신호대 잡음비를 계산하기 위하여 Golay 코드의 등 가임펄스를 제안하였고, 이를 실험적으로 증명해 보였다. 렌덤한 잡음신호에 대하여 S/N 비가 Golay 코드의 제곱근에 비례하였고, 이 방법은 고분자, 플래스틱, 고무와 같은 흡수가 큰 재료에서 유용함을 알 수 있었다.

• 한국군사과학기술학회지
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• 제22권3호
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• pp.332-340
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• 2019

Electronic warfare systems are needed to be advantageous in the modern war. Many radar threat signals with various frequency spectrums and complicated techniques exist. For detecting the threats, a receiver with wide and narrow-band digital processing is needed. To process a wide-band searching mode, a polyphase filter bank has become the architecture of choice to efficiently detect threats. A polyphase N-path filter aligns the re-sampled time series in each path, and a discrete Fourier transform aligns phase and separates the sub-channel baseband aliases. Multiple threats and CW are detected or rejected when the signals are received in different sub-channels. And also, to process a narrow-band precision mode, a direct down converter is needed to reduce aliasing by using a decimation filter. These digital logics are designed in a FPGA. This paper shows how to design and develop a wide and narrow-band digital receiver that is capable to detect the threats.

• 전기학회논문지
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• 제56권12호
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• pp.2189-2195
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• 2007

In this paper, we propose a newly developed selective reset waveform of a ac PDP using the wide erase pulse technique with the control of address bias voltage. Although it is generally understood that the wide pulse erasing methode shows the narrow driving margin in an opposite discharge type ac PDP, we could obtain a moderate driving margin in a 3-electrode surface discharge type ac PDP. The obtained driving margin shows a strong dependency on the sustain voltage and the address bias voltage. The lower the sustain and the address bias voltage, the wider the driving margin. The pulse width of the proposed waveform is only $10{\mu}s$, which gives additional time to the sustain period, hence increases the brightness. The brightness and contrast ratio increase about 20% together comparing to the conventional ramp type selective reset waveform with the driving scheme of 10 subfield ADS method. The driving margin was measured with the line by line addressed pattern on the white test panel of 2inch diagonal size and the discharge gas was Ne+Xe4%, 400torr.

• Journal of the Optical Society of Korea
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• 제17권2호
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• pp.177-181
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• 2013

We present an all-fiberized power-scalable, sub-nanosecond mode-locked laser based on a frequency-shifted-feedback ring cavity comprised of an erbium-doped fiber, a downshifting acousto-optic modulator (AOM), and a bandpass filter (BPF). With the aid of the frequency-shifted feedback mechanism provided by the AOM and the narrow filter bandwidth of 0.45 nm, we generate self-starting, mode-locked optical pulses with a spectral bandwidth of ~0.098 nm and a pulsewidth of 432 to 536 ps. In particular, the output power is readily scalable with pump power while keeping the temporal shape and spectral bandwidth. This is obtained via the consolidation of bound pulse modes circulating at the fundamental repetition rate of the cavity. In fact, the consolidated pulses form a single-entity envelope of asymmetric Gaussian shape where no discrete internal pulses are perceived. This result highlights that the inclusion of the narrow BPF into the cavity is crucial to achieving the consolidated pulses.

• 한국통신학회논문지
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• 제37A권12호
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• pp.1145-1151
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• 2012

본 논문에서는 binary offset carrier (BOC) 신호 추적을 위해 주변 첨두는 완벽히 제거하면서, 기존의 BOC 상관함수들보다 좁은 폭의 주 첨두를 갖는 새로운 BOC 상관함수를 제안한다. 구체적으로는 BOC 신호를 구성하는 부반송파 펄스를 펄스 구간이 더 좁은 두 개의 펄스의 합으로 해석하고, 그에 따른 부분상관함수들을 생성한다. 이후 부분상관함수들을 재조합함으로써 주변 첨두를 제거하면서도 기존 BOC 상관함수보다 상관함수의 폭이 좁은 새로운 상관함수를 생성한다. 모의실험을 통해 제안한 상관함수를 이용한 경우, 기존의 상관함수들을 이용한 경우들에 비해 더욱 향상된 신호 추적 성능을 가지는 것을 보인다.