• 전기산업
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• v.2 no.4
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• pp.64-67
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• 1991

• The Korean Journal of Financial Studies
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• v.5 no.1
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• pp.105-133
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• 1999

주가(株價)의 예측(豫測)이 가능하다는 최근 실증결과들로 말미암아 증권시장의 효율성(效率性)에 강한 의문이 제기되고 있다. 주가(株價)의 반전(反轉)(price reversal)이 주가의 예측을 가능하게 한다는 것이다. 혹자는 증권시장이 정보에 과잉반응(過剩反應)을 나타내고 그 후 이를 수정함으로서 주가의 반전이 나타난다고 주장한다. 또 혹자는 호가(呼價)스프레드(spreads)의 존재로 인하여 주가의 반전이 있을 수 있다고 한다. 실제로, 때로는 매수호가에 때로는 매도호가에 거래가 이루어지고 있기 때문이다. 본 연구는 KOSPI 200 구성주식의 일별(日別)수익률 자료를 이용한 실증분석에서 다음과 같은 중요한 사항들을 발견하였다. 첫째, 한국증권시장에 주가반전(株價反轉)이 있다는 것을 확인하였으며, 이러한 단기 주가반전의 주된 원천은 시장(市場)의 과잉반응(過剩反應)이 아니라 호가(呼價)스프레드라는 것을 발견하였다. 일중(日中)에도 물론 주가가 반전하고 있음을 확인하였다. 둘째, 호가스프레드에 의한 변동성으로 말미암아 거래가격을 기준으로 한 일별수익률의 변동성(變動性)이 상당히 과대(過大) 추정(推定)될 수 있음을 발견하였다. 일별수익률 분산의 약 15%는 호가스프레드로 설명(說明)할 수 있었다. 마지막으로, 본 연구결과는 다음과 같은 점을 시사(示峻)하고 있다. 우리 나라에서 호가스프레드는 딜러마켓에서와 같은 '마진'의 의미가 전혀 없다. 따라서 호가스프레드의 크기를 결정하는데 있어 중요한 역할을 하는 '호가단위(呼價單位)'를 적절한 수준으로 가능한한 작게 하는 것이 바람직 할 것이다. 이는 매도자와 매수자의 의견접근을 용이하게 함으로서 매매(賣買)의 성립(成立)을 촉진할 뿐만 아니라, 특히 기관투자자의 거래비용(去來費用)을 줄일 수 있으며, 또 호가스프레드로 인한 앞서의 불필요한 변동성(變動性)을 줄이는 효과도 아울러 기할 수 있을 것이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.445-450
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• 2017

In this paper, the directional coupler with half-power division is designed and fabricated by using the vertical coupling structure based on the CPW transmission-line. Even-mode and odd-mode of the vertical coupling structure can be analyzed by the conventional CPW-line and the CBCPW-line, respectively, with half thickness of the substrate. The directional coupler is designed by using the tefron substrate with the dielectric constant of 2.55 and the thickness of 0.76mm. Manufactured directional coupler has the center frequency of 2.45 GHz and the bandwidth of 66.1%. Also, the return loss and isolation are 19.52dB and 19.47dB, respectively, at the center frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.151-157
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• 2013

In this paper, a comparative analysis of PBTI induced device degradation in nanowire n-channel junctionless and inversion mode Multiple-Gate MOSFET(MuGFETs) has been performed. It has been observed that the threshold voltage is increased after PBTI stress and the threshold voltage variation of junctionless device is less significant than that of inversion mode device. However the degradation rate of junctionless device is less significant than that of inversion mode device. The activation energy of the device degradation is larger in inversion mode device than junctionless device. In order to analyze the more significant PBTI induced device degradation in inversion mode device than junctionless device, 3-dimensional device simulation has been performed. The electron concentration in inversion mode device is equal to the one in junctionless device but the electric field in inversion mode device is larger than junctionless device.

• Journal of the Korea Society of Computer and Information
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• v.17 no.3
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• pp.105-111
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• 2012

Photoplethysmogram is widely used to measure heart rate and arterial blood oxygen saturation in human. This paper describes implementation a photoplethysmography monitoring system that uses 780nm and 940nm length infrared light in radial artery. That system used combinations of 8 LEDs and 2 photoelectricities. When recorded on the skin over radial artery, the radial pulse wave was inverted. The mechanism of inverted pulse wave skin, which was reduced during systolic period and increase during diastolic period of the cardiac cycle. Through this system, we discovered optimal environments and combinations of sensors in both penetration type and reflection type. These results suggest that radial arterial wall way reflect infrared ray.

• Proceedings of the Optical Society of Korea Conference
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• 1997.08a
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• pp.45-45
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• 1997

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.11-16
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• 2006

The object of this study is to develop new examination techniques for detecting the debonds in adhesive interface of different kinds of the material. Ultrasonic signal was modeled by theoretically analyzing ultrasonic propagation phenomenon of the adhesive interface and debonding interface. The test method using the phase reversal of the debonding interface applied to the FRP/Rubber test block. Aluminum/Rubber test block with the flat bottom hole was manufactured to quantitatively evaluate the minimum detection ability of the defects. The pulse echo reflection method and the phase reversal method were mutually compared and it was estimated that the phase reversal method could detect the debonds on the basis of the theoretically predicted ultrasonic signal and ultrasonic test data.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.9-16
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• 2009

The object of this study is to develop new examination technique for detecting debond in adhesive interface of different kinds of materials. Ultrasonic signal was modeled by theoretically analyzing ultrasonic propagation phenomenon of the adhesive interface and debonding interface. The test method using the phase reversal of the debonding interface applied to the FRP/Rubber test block. Aluminum/Rubber test block with the flat bottom hole was manufactured to evaluate quantitatively the minimum detection ability of defects. The pulse echo reflection method and the phase reversal method were mutually compared and it was estimated that the phase reversal method could detect the debond on the basis of the theoretically predicted ultrasonic signal and ultrasonic test data.

• International Area Studies Review
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• v.12 no.3
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• pp.195-216
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• 2008

It is generally accepted that the momentum strategies are effective in the short-term, and the contrarian strategies are profitable in the long run in major stock markets in the world. In Korean market, however, the contrarian is considered effective investment strategy both in the short- and long-term. We investigate whether this is true after 1999, and try to find out the reasons for this phenomena. We found that the contrarian strategies are still effective. Foreign investors showed consistent investment behavior both in Korean and abroad: they followed momentum in the short-tem, and contrarian in the longer-term. The individual investors, who are thought to be noise trader, showed different behavior. They followed contrarian strategies both in the short-and long-term. The reason that the contrarian is observed in Korean market regardless of the investment horizon is thought to be the irrtional behavior of individual investors.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.234-235
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• 2003

오늘날 급속한 인터넷 사용량 증가로 인해 광통신 시스템의 고속화와 대용량화의 필요성은 점점 커지고 있다. 이에 광신호 처리에 있어서 초고속 광 스위칭과 파장분할 다중화 방식이 활발히 연구되고있으며, 특히 주기적으로 분극 반전된 리튬나오베이트(LiNbO$_3$：PPLN)를 이용한 스위칭 소자나 파장 변환기에 대한 연구가 많이 진행되고 있다. PPLN 제작을 위하여 최근에는 고압의 전계를 리튬나오베이트(LiNbO$_3$)에 인가하는 방법이 우수한 특성으로 인하여 주로 사용되고 있다. (중략)