• 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.

• Korean Journal of Optics and Photonics
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• v.30 no.2
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• pp.59-66
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• 2019

We report highly sensitive detection of myocardial infarction biomarkers, such as myoglobin and cTnI, within several hundred seconds using a rotating-analyzer ellipsometer and a biosensor with biochips fabricated on a $SiO_2$-coated tilted silicon substrate. We choose the running buffer to be pure phosphate-buffered saline (PBS) or 10% mixed human serum. When we choose the running buffer to be pure PBS, we obtain diagnostic densities of pure myocardial infarction biomarkers of up to 1 ng/ml and 5 pg/ml respectively. Meanwhile, when we use PBS with 10% human serum, the measured densities of myoglobin and cTnI were up to 1 ng/mL and 1 pg/mL respectively. The measured diagnostic densities are less than 1/15 and 1/80 (in cases of myoglobin and cTnI respectively) of those referenced by the World Health Organization.

• Electronics and Telecommunications Trends
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• v.30 no.6
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• pp.42-49
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• 2015

질화물 반도체 기반 가시광 청색 Light Emitting Diode(LED) 기술은 디스플레이의 Back Light Unit(BLU)뿐 아니라 일반 조명에 활용되며 우리 실생활에서 매우 밀접하게 사용하고 있다. 가시광보다 짧은 파장을 가지는 자외선 LED의 경우 경화기 및 위폐감지기에 기존의 유해 가스를 사용하는 자외선 램프를 대체하고 있다. 자외선 광원의 또 다른 거대 시장으로 살균 및 정화, 의료 및 바이오 응용 시장에서 자외선 램프를 대체할 수 있는 자외선 LED 기술이 활발히 발전하고 있다. 본고에서는 이들 자외선광원 시장동향과 국내외 자외선 LED의 기술동향을 파악하므로 앞으로 연구개발의 방향을 모색하고자 한다.

• Polymer Science and Technology
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• v.15 no.3
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• pp.274-285
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• 2004

콜로이드 결정 (Colloid crystal)이란 용액 상에서 부유 하는 작은 입자들의 자기 조립 (self-assembly)에 의해 형성된 주기적인 2차원 혹은 3차원 구조를 말한다. 이러한 결정 구조는 광학 필터나 스위치, 광 밴드 갭 재료, 바이오 센서 등의 과학 기술적인 응용을 비롯하여 액화 물질의 상 변화 등과 같은 물리적 현상을 규명함에 있어서 중요한 모델을 제시한다. 특히 최근에 콜로이드의 자기 조립체는 자연적으로 갖게 되는 주기적인 유전율 변화 때문에 빛의 진행 방향이나 특성을 조절할 수 있는 광자 결정 (Photonic Crystal) 구조 제작의 경쟁력 있는 접근 방법으로 각광 받고 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.88-89
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• 2003

산업이 고도로 발달함에 따라 생산 부품의 소형화와 정밀도가 크게 요구되고 있다. 특히 최첨단 제품인 반도체와 광통신 부품, 그리고 광학 부품 등에 있어 이러한 추세가 두드러지게 나타나고 있다. 이에 따라 이들 부품들에 대한 제조 공정 못지 않게 초정밀 측정에 대한 관심도 꾸준히 늘고 있다. 뿐만아니라 요즘 새롭게 부각되고 있는 생명 공학 기술(Bio-Technology)과 나노기술(Nano-Technology)을 이용한 바이오센서나 칩, 그리고 타소 나노 튜브 등을 제작하거나 검사를 할 때도 초정밀 측정을 필요로 하게 된다. (중략)

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.306-315
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• 2021

This study analyzed the effects of light-shielding curtains and halogens on spectrum when acquiring hyperspectral images in a greenhouse. The image data of tarp (1.4*1.4 m, 12%) with 30 degrees of angles was achieved three times with four conditions depending on 14 heights using the automatic image acquisition system installed in the greenhouse at the department of Southern Area of National Institute of Crop Science. When the image was acquired without both a light-shielding curtain and halogen lamp, there was a difference in spectral tendencies between direct light and shadow parts on the base of 550 nm. The average coefficient of variation (CV) for direct light and shadow parts was 1.8% and 4.2%, respective. The average CV value was increased to 12.5% regardless of shadows. When the image was acquired only used a halogen lamp, the average CV of the direct light and shadow parts were 2 .6% and 10.6%, and the width of change on the spectrum was increased because the amount of halogen light was changed depending on the height. In the case of shading curtains only used, the average CV was 1.6%, and the distinction between direct light and shadows disappeared. When the image was acquired using a shading curtain and halogen lamp, the average CV was increased to 10.2% because the amount of halogen light differed depending on the height. When the average CV depending on the height was calculated using halogen and light-shielding curtains, it was 1.4% at 0.1m and 1.9% at 0.2 m, 2 .6% at 0.3m, and 3.3% at 0.4m of height, respectively. When hyperspectral imagery is acquired, it is necessary to use a shading curtain to minimize the effect of shadows. Moreover, in case of supplementary lighting by using a halogen lamp, it is judged to be effective when the size of the object is less than 0.2 m and the distance between the object and the housing is kept constant.

• Journal of the Korean Chemical Society
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• v.65 no.3
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• pp.234-239
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• 2021

• KSBB Journal
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• v.24 no.1
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• pp.1-8
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• 2009

In the past decade, we have observed rapid advances in the development of biochips in many fields including medical and environmental monitoring. Biochip experiments involve immobilizing a ligand on a solid substrate surface, and monitoring its interaction with an analyte in a sample solution. Metal nanoparticles can display extinction bands on their surfaces. These charge density oscillations are simply known as the localized surface plasmon resonance (LSPR). The high sensitivity of LSPR has been utilized to design biochips for the label-free detection of biomolecular interactions with various ligands. LSPR-based optical biochips and biosensors are easy to fabricate, and the apparatus cost for the evaluation of optical characteristics is lower than that for the conventional surface plasmon resonance apparatus. Furthermore, the operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in LSPR research and also describe the LSPR-based optical biosensor constructed with a core-shell dielectric nanoparticle biochip for its application to label-free biomolecular detections such as antigen-antibody interaction.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.285-290
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• 2013

Recently a novel bio refinery process with using nonedible biomass, especially microalgae, has been developed in order to directly reduce $CO_2$ concentration from flue gas and simultaneously produce renewable bio fuel. Micro algae-to-biofuel processes are composed of microalgae cultivation, harvesting, lipid extraction, and bio fuel conversion. So, there are concerns about the energy efficiencies of bio refinery processes. In this study, the net energy ratio of microalgae processes were calculated for the microalgae produced from a pilot photobioreacto using $CO_2$ released from coal combustion. In this study, trans-esterification and pyrolysis processes were used to analyze the net energy efficiencies. Micro algae-to-biofuel processes might produce bio fuels with the higher energy than that of the total consumed energy for cultivation, harvesting, extraction and conversion. If the lipid content of microalgae was higher, the trans-esterification conversion process was more effective than that of pyrolysis process.

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.243-244
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• 2007