• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.228-234
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• 2002

We report theoretical investigation on the polarization selective coupling characteristics of a side-polished fiber directional coupler with a thin metal interlayer. Based on normal mode theory the coupling properties of the device under various structural conditions are analyzed. It is shown that the coupling strength between TE modes weakens rapidly with increase or metal interlayer thickness, whereas that between TM modes becomes stronger. The design conditions of the polarization splitter using the coupler to achieve high extinction ratio and low insertion loss are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04b
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• pp.97-100
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• 2002

We analyzed the excitation coefficients and the extinction ratio as a function of waveguide width, center to center distance, and angle of input waveguide for a directional coupler. The variation of thc difference between excitation coefficients is similar to that of the extinction ratio. Also, the smaller the difference between those is, the better the extinction ratio is. This concept will have application to devices using optical coupling.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.223-224
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• 2001

고온 소각공정은 산업용 및 가정용 폐기물의 처리시 부피의 현격한 감소뿐만 아니라 유해성 유기물을 무해한 형태로 전환시켜 주는 장점을 지니고 있다. 그러나 유해 중금속의 경우 소각공정 중 소멸되거나 새로이 생성되지 않고 화학적, 물리적 변형만 일어날 뿐, 그 유해성은 소멸되지 않고, 고온 휘발성 유해중금속의 경우 일부 환경으로 배출되므로 잠재적으로 심각한 대기오염원이 되고 있다(1990). 최근에는 이러한 고온 휘발성 중금속의 효과적인 제거를 위한 연구로 여러 가지 무기질 흡착제를 이용한 고온 흡착제거 연구가 활발히 이루어지고 있다(1998, 1999). (중략)

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.105-110
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• 2007

A tunable band-pass filter of fiber Bragg gratings incorporating the Sagnac loop interferometer configuration is presented. The proposed band-pass filter with extinction ratio 20 dB has practical advantages in terms of price and performance in comparison with the conventional band-pass filter using a circulator.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.730-732
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• 2003

의료영상정합을 통해서 이상징후 발현시점과 소멸시점의 기능영상을 비교함으로써 기능이상부위를 판별하는 것은 질환의 진단에 매우 유용하다. 본 논문에서는 기존 변화시점간 기능영상 감영법이 정확한 소멸시점에서의 영상 취득이 어려움으로 인해 정확도가 떨어질 우려가 있는 점을 개선하고자 뇌 혈류이상을 나타내는 뇌기능영상인 SPECT의 변화시점 기능이상부위 추출을 위하여 정상인집단 영상의 비선형 영상정합기법과 영상평균화를 통해 뇌기능영상 템플릿을 구축하였다. 또한 이를 기반으로 영상감영을 수행함으로써 간질환자의 발작중(ictal) SPECT 뿐만 아니라 발작간(interictal) SPECT에서도 뇌혈류의 이상을 정확히 분석할 수 있는 3차원 추출가시화 방법을 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.511-514
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• 2001

본 논문에서는 Ad Hoc 네트워크에서의 라우팅 알고리즘인 TORA 의 라우팅 유지관리 방법에서 발생하는 비효율적인 컨트롤 패킷들을 줄이는 방법을 제안한다. Adv-TORA에서는 DN(Downstream)이 소멸되는 노드에서 STP(Stop) 패킷을 주변 노드에 발송하여 끊어진 경로로 데이터 패킷이 발송되는것을 사전에 방지한다. 또, DN 소멸 노드의 주위에서 그래프의 재구성 작업이 일어났던 TORA 와는 상이하게, 단순히 지역적 라우트 경로를 초기화시킴으로서 TORA 의 컨트롤 패킷 부담을 줄인다. 또한, 통신에 참여하지 않는 노드들의 불필요한 라우트 정보 유지를 최소화하고, 라우트 요구 발생시에만 라우트 재구성 작업을 수행한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.224-231
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• 2013

Defining the concept of prominent audio content as the most informative audio content from the users' perspective within a given unstructured audio segment, we propose a simple but robust intensity-based attack/release pattern features to detect the prominent audio content. We also propose a web-based annotation procedure to retrieve users' subjective perception and annotated 18 hours of video clips across various genres, such as cartoon, movie, news, etc. The experiments with a linear classification method whose models are trained for speech, music, and sound effect demonstrate promising - but varying across the genres of programs - results (e.g., 86.7% weighted accuracy for speech-oriented talk shows and 49.3% weighted accuracy for {action movies}).

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.62-65
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• 2002

파랑은 주로 먼바다에서 바람에 의해 생성되어 육지로 전파해오면서 천수, 굴절, 회절, 반사, 부서 짐 등의 여러 가지 변형의 과정을 거친다. 이러한 파랑의 변형을 예측하는 한 방법은 비압축성 유체와 비회전류의 연속방정식인 Laplace 방정식을 지배 방정식으로 하고 해수면에서의 운동학적 경계조건과 동역학적 경계 조건, 그리고 바닥에서의 운동학적 경계조건을 적용하여 해를 구한다. (중략)

• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.266-271
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• 2009

We designed a thermo-optic switch based on a directional coupler with not only a high extinction ratio but also significantly low power consumption. The switch operates by using the thermo-optic effect of the polymer which the refractive index changes by heating the electrode. If the electrode is not powered (OFF), the input light will be coupled completely to the other waveguide. When the electrode is powered at a certain level (ON), input light launched into the input waveguide will remain in that waveguide due to the lower index adjusted in the other waveguide. The switch based on the directional coupler was designed using the generalized extinction ratio curve and the lateral shift of the input waveguide. The coupling length is 1,610 ${\mu}m$ and the extinction ratios are -28 and -30 dB for ON and OFF states, respectively. The electrode structures were optimized by thermal analysis. The transported heat into the waveguide is increased, as the electrode width (w) is increased and the center distance between the electrode and the waveguide (d) is decreased. Also, because the heat generated in the electrode affects the other waveguide, the temperature difference between two waveguides is varied as the given w and d. There are specific conditions which have the maximum of the temperature difference. That of the temperature difference is increased as the width and the temperature of the electrode are increased. Especially, when the switch is designed using the condition with the maximum of the temperature difference for switching, the temperature of the electrode can be decreased. We expect this condition will be the novel method for the reduction of the power consumption in a thermo-optic switch.

• Korean Journal of Environmental Biology
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• v.23 no.3 s.59
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• pp.304-314
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• 2005

The occurrence of cyanobacterial bloom in Korean lakes of the summer is generalized. The characteristic of cyanobacterial community was explored. And the developmental stage of cyanobacterial bloom was divided into three phases, 'preparatory phase', 'bloom phase' and 'extinction phase' Cyanobacterial bloom started during the end of June at site 1, transition Bone of Lake Daecheong. The period of water bloom in normal year was about 60~70 days at site 4, lacustrine Bone, but it was unusually 11 days from July 19 in 1999. M. aerugilnosa first occurred in June, had a peak of standing crop curve from the end of August to the beginning of September in 1998 and 2002 and the end of July in 1999 and 2001. The standing crop of M. aeruginosa occupied $68.1\%$ of phytoplankton, $74.2\%$ of cyanobacteria and $88.8\%$ of genus Microcystis, Anabaena spp. first occurred in April, was above 10,000 cells $mL^{-1}$ from the end of August to about the middle of September in 1998. The effect of rainfalls on cyanobacterial bloom was different according to the phases. The rainfalls of preparatory phase assist the growth of cyanobacteria, but accelerate the decrease of cyanobacteria in extinction phase. In bloom phase, the heavy rainfalls reduce the development of the bloom, while the slight ones display only a little effects.