• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 동계 학술대회 논문집
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• pp.457-463
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• 2000

• 조명전기설비학회논문지
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• 제30권2호
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• pp.11-19
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• 2016

By incorporating a polarization-diversity loop configuration, we have demonstrated the inline switching of transmission and reflection spectra of one of two short-period fiber gratings (SPFGs) with different resonance wavelengths without reconfiguring the filter structure. The proposed filtering apparatus consists of a fiber-pigtailed polarization beam splitter, two SPFGs, and three quarter-wave plates (QWPs). The proposed filter can independently choose the transmission or reflection spectrum of each SPFG through the appropriate adjustment of the orientation angles of the QWPs within the filter without additional optical switches and couplers. The average insertion loss, band rejection ratio, and side-mode suppression ratio of the fabricated filter were measured as ~4.59, ~17.88, and ~19.67dB, respectively.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.1-7
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• 2015

In this paper, we propose a second-order fiber flexible comb filter based on a polarization-diversity loop(PDL). The proposed filter consists of a polarization beam splitter, four half-wave plates(HWPs), and three high birefringence fiber(HBF) segments. In the previous Solc-type second-order filter based on the PDL, HBF segments were fusion-spliced with a fixed angle offset between their principal axes with each other. But, the proposed filter implemented by inserting two HWPs between three HBF segments has a great flexibility in adjusting relative angular difference between the principal axes of two adjacent HBF segments. Owing to this flexibility, second-order transmission spectra, which had a channel spacing of ~0.8nm, could be interleaved by controlling the orientation angles of four HWPs. The output transmission spectra of the proposed filter were theoretically analyzed and experimentally verified.

• 한국광학회지
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• 제30권2호
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• pp.67-73
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• 2019

본 논문에서는 다양한 배열을 가지는 기판에서의 특이 광 투과 센서 시스템의 센싱 성능을 조사하였다. 보조파장 홀 어레이 구조는 어레이의 주기와 격자 배열을 달리하여 제작하였고, 특이 광 투과 센서 시스템으로 제작한 기판에서의 투과 스펙트럼을 측정하였다. 굴절률이 다른 유전물질을 이용하여 투과 스펙트럼을 관찰한 결과 어레이의 주기가 증가할수록 센서의 민감도가 높아짐을 보았다. 또한 육각형 어레이에서 측정한 결과와 비교하였을 때 정사각형 어레이에서 센서의 성능이 향상됨을 입증하였다.

• 한국재료학회지
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• 제9권1호
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• pp.42-45
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• 1999

The room temperature optical transmission spectra of GaN /InGaN/GaN single quantum wells (SQW) and InGaN/GaN heterostructures grwon by low pressure metalorganic chemical vapor deposition have been measured. The dependence of the absorption edges of the GaN/InGaN/GaN SQW on the well width has been determined from the transmission spectra. The result shows that the absorption edge of GaN/InGaN/GaN SQW shifts towards lower energy as increasing the well width. The dependence of the absorption edges of the InGaN/GaN heterostructures on InN mole fraction has also been determined from the transmission spectra. The result is compared with calculated values obtained from Vegards's laws. Our result shows a good agreement with the calculated values.

• 한국광학회지
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• 제12권5호
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• pp.401-405
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• 2001

본 논문에서는 반사대역 내부에 분리된 다수의 통과대역을 갖는 영역이 분리된 첩 광섬유 격자를 이용하여 각 채널을 독립적으로 제어할 수 있는 광 툭과 필터를 제안하였다. 영역이 분리된 첩 광섬유 격자는 원하는 영역을 설정할 수 있는 슬릿을 사용하여 제작되었다. 분리된 대역은 압전소자에 광섬유 신장기를 부착하여 조절하였고, 조절된 반사 대역은 채널을 독립적으로 선택하는데 사용되었다. 광대역 광원과 파장가변 레이저를 사용하여 투과 스펙트럼의 파장이동에 따른 입력 채널의 선택을 보였다.

• Journal of the Korean Wood Science and Technology
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• 제26권2호
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• pp.51-58
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• 1998

Structural changes of cellulosic fibres during the papermaking process were studied by analysis of FTIR spectra collected by the transmission method. The spectra were obtained from a carefully prepared handsheet, using a special infra-red (IR) cell suitable for evacuating the sample. The deconvolution technique was also applied for sharpening the FTIR spectra in the frequency range of the OH and CH stretching bands, which gave detailed information on the structural changes of cellulose. The intensity of some bands was decreased by predrying the sample as a result of the removal of adsorbed moisture. An increase in intensity of some bands in the frequency range of 3700 to $3200cm^{-1}$ was shown at a higher beating level. This increase in intensity was caused by changes in the crystal domain of cellulose resulting from the exposure of the crystalline area on the fibre surface.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1082-1082
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• 2001

Extrusion is one of the most important processes in polymer industry. The characterization of the polymer melt during processing will improve this process noticeably, One possibility of characterizing the actual processed polymer melt is the inline near infrared (NIR) spectroscopy, With this method several polymer properties can be observed during processing, e.g. composition, moisture ormechanical properties of the melt. For this purpose probes for transmission and reflection measurements have been developed, withstanding the high temperatures and pressures appearing during extrusion process (tested up to 300$^{\circ}C$ and 10 ㎫). For the transmission system an optical bypass was developed to eliminate disturbing spectral influences and hence increase the long term stability, which is the prerequisite for an industrial application. Measurements in transmission and reflection produced comparable results (or blending processes, where the prediction error was less than 1%. An optimum RMSEP of only 0.24% was found for preprocessed polymer blends measured in transmission on a laboratory extruder. A transflection measurement allowed for the first time the recording of relevant NIR-spectra in the screw area of an extruder. The application to a (PE+PP) blending process delivered promising results. This new measurement mode allows the observation of the ongoing processes within the screw area, which is of maximum Interest for reactive extrusion processes. Due to economic reasons the calibration transfer between different extrusion systems is also of high importance. Investigations on simulated and real-world spectra showed that a calibration transfer is possible. A new method alternatively to the well-known direct standardization procedures was developed, which is based on an automatic data pretreatment. This procedure delivers comparable results for the calibration transfer. Overall this paper presents concepts, components and algorithms for the inline near infrared (NIR) spectroscopy for polymer extrusion, which allows the use of it in a real industrial extrusion process.

• 한국결정학회지
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• 제8권2호
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• pp.105-110
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• 1997

CdS/CuInSe2 태양전지에서 창측재료로 1μm 두께의 CdS박막을 1x10-3mTorr의 진공하에서 CdS source 온도를 800-1100'C로 하고 기판의 온도를 50-200℃로하여 진공증차겁으로 제조하였다. 증착된 CdS박막의 구조적, 전기적, 광학적 특성조사는 x-ray diffractometer(XRD), scanning electron microscope(SEM), 전기비저항 측정, Hall measurement 그리고 optical transmission spectra로 행하였고, 각막들의 성분분석은 energy dispersive analysis of X-ray (EDAX)를 가하나, 광투과도는 감소하였다. 이때 증착된 CdS 박막들은 모두 hexagonal 구조를 가지고 있었으며, 결정성은 기판유리를 딸 (002)면으로 형성되었다. CdS Source 온도가 1000℃에서 증착된 CdS 박막이 0.9(S/cm)의 가장 높은 전기 전도도를 나타내었다. 또한 기판온도를 100'C로 제조한 CdS 박막이 전기비저항은 40(Ω,cm)이었고 광투과도는 80% 이상의 값을 나타내어 CdS/CuInSe2 태양전지의 창측재료로 적합했다.

• 한국광학회지
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• 제32권3호
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• pp.126-132
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• 2021

본 논문에서는 특이 광 투과 현상 센서에서 보조 파장 홀 패턴에 입사되는 광원의 각도 조절을 통해 센서의 민감도를 측정 및 분석하여 이를 극대화할 수 있는 방법을 고안하였다. 입사파 광원을 평행화된 광원과 각도가 서로 다른 두 개의 집속화된 광원 총 3개의 광원을 시스템적으로 설계하여 서로 다른 각도로 보조 파장 홀 패턴에 입사되게 제작하였다. 그리고 증류수(n=1.333)와 굴절률 정합액(n=1.360, 1.380)을 사용하여 투과 스펙트럼을 측정하고 센서의 민감도를 계산한 결과 평행화된 광원을 사용하였을 때 센서의 민감도가 향상됨을 확인하였다.