• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.355-358
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• 2003

We report experimental results on the wavelength and polarization selective coupling properties of fiber-to-planar waveguide coupler having a thin metal intermediate layer. The influence of the metal layer thickness and the refractive index of the superstrate on the device properties has been measured and explained. The proposed device exhibited various application possibilities including polarizers, modulators, and sensors.

• Language and Information
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• v.4 no.1
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• pp.130-140
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• 2000

이 논문에서는 피동접사 '이, 히, 리, 기'와 결합하는 피동형과 관련된 형태·통사적 문제를 전산적 관점에서 다룬다. 전산처리에서 이러한 피동형의 형태적 문제는 다음과 같다. 첫째, 피동접사 '이, 히, 리, 기'와 결합할 수 있는 타동사 어간의 분포가 제한되어 있다. 둘째, 타동사 어간이 결합할 수 있는 피동접사는 고정접사는 고정되어 있다. 셋째, 피동형 중에 타동사 어간과 피동접사가 결합할 대 형태적으로 변화하는 것들이 있다. '나누다/나뉘다, 모으다/모이다, 잠그다/잠기다, 자르다/잘리다'등이 여기에 해당된다. 이러한 형태적 문제 외에도 전산처리에서 피동형과 관련된 통사적 문제는 다음과 같다. 첫째, 능동형의 타동사가 피동형이 되면서 논항구조도 함께 변화한다. 둘째, 피동문의 행동주가 문장에서 생략되는 경우가 종종 있다. '문제가 쉽게 풀리었다','소리가 잘 들린다'등이 이에 해당된다. 이 논문은 한국어 피동접사 '이, 히, 라, 기'와 결합하는 피동형의 형태·통사적 특징을 전산적으로 처리하는 것이 목적이다. 이를 위해 표상모형으로는 자질구조를, 구현도구로는 Malage를 사용한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.4
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• pp.278-285
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• 1990

It is well know that optical oupler that is composed of the polished single-mode optical fiber can separate two arbitrary wave lengths. Wavelength division ranges of the WDM optical coupler that is made of the bending fiber with radius R vary with the center wavelength of the signal and spacing between two cores. In this paper, when optical fiber is fixed with the radius R, We proposed the spacing between two cores that can provide minimum division range. Also, We proposed the minimum radius R necessary to separate two arbitary wavelengths of the signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.9
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• pp.862-876
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• 1991

In this theses, the procedure for finding the equivalent immittance of an n-line coupled structures is presented in terms of the normal mode parameters of the n-line coupled system. The above generalized equations can be applied to the various Coupled structures including directional couplers, DC blocks, bandpass/band elimination filters, and various other uniformly coupled filters. The design equations are based on a simplified TEM(Quasi TEM) mode. The obtained results and the definition of the scattering parameters for a general coupled line four port with arbitrary terminations are used to present the procedure to determine the optimum physical dimensions matching the given load impedances connected to input, output port. Multiple coupled rnicrostrip two-port with three lines circuit designed shows little discrepancy between the conventional method and this one. Four port with five lines were fabricated on teflon substrate($e$r=2.55) with its thickness h=l.588mm designed at the center frequency, 4 GHz. Their measured results are fairly close to the ones by computation.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.420-427
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• 1993

Dielectric thin film mirrors are embedded in multimode and single-mode fibers by a fusion splicing technique. The fibers with $45{\circ}$ angled embedded mirrors serve as ultra-compact directional couplers with low excess optical loss of 0.2 dB for multimode and 0.5 dB for single mode at 1.3 ${\mu}m$ and excellent mechanical properties. The reflectance is wavelength dependent and strongly polarization depencient. Far-field scans of the reflected output power measured with a white-light source show a pattern which is almost circularly symmetric with aspect ratio of 1.09 at 5% of the peak power. The splitting ratio in a multimode coupler measured with a diode laser source is much less dependent on input coupling conditions than in conventional fused biconical-taper couplers, indicating that these couplers are less susceptible to modal noise occuring in optical fiber communication systems. Spectral properties of multilayer internal mirrors normal to the fiber axis have been investigated experimentally, and a matrix analysis has been used to explain the results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.145-150
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• 2023

Non-uniform optical taper waveguides have been widely used as devices for high-efficiency mode coupling, as they are integrated with single-mode optical fibers or photonic crystal waveguides. In this paper, we present a new platform for chemical sensing and bio-sensing using optical taper waveguides with these characteristics. The principle of operation is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multi-mode interference coupler (MMIC). First, the curvature characteristics of taper sections of DC and MMIC is explained, and the design specifications of optimized taper waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the change in refractive index of sensing analyte is numerically analyzed. Numerical results show that as the length of couplers increases, the effective index per change in refractive index unit (RIU) of analyte increases, and that sensitivity can be tuned using taper DC and MMIC design techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2067-2080
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• 1994

Recently, joint blind equalization and carrier recovery for digital mobile transmission system is of growing interest. In this paper, we describe new receiver structure of joint godard blind equalizer and various recovery loop for QAM modulated signal. After a brief review of Godard blind equalizer and MAP estimation Costas loop, Generalized Costas loop, Leclert loop, Angular form loop, we present two kinds of receiver structures for joint blind equalization and carrier recovery. Using a Monto Carlo simulation technique, we can confirm that two kinds of receiver structures operate very well in the steady state.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.262-266
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• 1997

The CNDO/2 calculations have been applied on cluster models for the representative hydroxyls on silica surface to get Wiberg bond orders, total energies, LUMO energies, dipole moments, and formal charge densities. The Br${\ddot{o}}$nsted acidities of suggested models for the hydroxyls were explained in terms of Wiberg bond orders. The calculated bond orders of cluster models have been changed remarkably according to the hydrogen bond. However the Lewis acidities of terminal hydroxyls on silica surface were not related to the structure of hydroxyls.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.334-336
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• 2003

얼굴인식 연구는 얼굴표현에 집중하여 연구가 이루어져 왔으며, 이에 따라 최종 인식단계에서는 간단한 분류기가 적용되었다. 그러나, 보다 강건한 분류 성능을 얻기 위해서는 복잡한 분류기를 도입할 필요성이 있다. 복잡한 분류기를 사용하면서, 얼굴인식의 특성상 온라인 학습을 가능하게 하기 위해서는 이진 분류기 분해/결합 방법을 도입한다. 이러한 기법으로는 OPC와 PWC가 대표적이다. 본 방법의 성능은 기본이진 분류기의 성능에 좌우되기 때문에 SVM을 적용한다. 본 논문에서는 대표적인 방법인 OPC와 PWC의 장단점을 설명하고, 거절 조건을 갖는 이들 분류기들의 순차 결합 방법을 제안한다. ORL얼굴데이터 베이스에 대한 실험에서는, 제안하는 방법을 통해 얼굴인식 성능을 향상시킬 수 있음을 보인다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.347-351
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• 2003

본 논문에서는 전력 분배비를 변화시킬 수 있는 전력 분배기/합성기를 설계하였다. 전력 분배기/합성기의 ${\lambda}/4$ 전송선로 특성 임피던스를 결합선로 또는 하이브리드로 변환하여 설계하였다. 결합 선로나 하이브리드의 결합포트와 격리포트를 동시에 On/Off시킴으로써 변화하는 임피던스를 이용하여 전력 분배비가 1:1에서 1:0으로 즉 전력이 두개의 포트에 같은 크기로 전달되다가 모든 입력이 하나의 출력포트로 모두 전달되는 전력 분배기를 설계하였다.