• 통합자연과학논문집
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• 제11권2호
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• pp.113-120
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• 2018

This study was planned to prepare the high strength hydrogel ophthalmic lens containing isocyanate group and nanoparticles. HDI with carbon nanoparticles were used as additives for the basic combination of HEMA, MA and MMA, and the materials were copolymerized with EGDMA as the cross-linking agent and AIBN as the initiator. The mixture was heated at $100^{\circ}C$ for an hour to produce the high performance hydrogel ophthalmic lens by cast mold method. Measurement of the physical characteristics of the produced material showed that the refractive index was in the range of 1.4027~1.4600, water content 25.21~44.01%, contact angle $54.18{\sim}72.94^{\circ}$, visible light transmittance 53.03~92.09%, and tensile strength 0.1024~0.2359 kgf and breaking strength was 0.0872~0.2825 kgf. The results showed an increase of refractive index while the decrease in water content. And also, the breaking strength was highest when the addition ratio of HDI was 5%(wt). As a result of the absorbance measurement, no significant difference was observed in all the samples, so it can be judged that the stabilization of nanoparticles in the polymer was maintained.

• 한국기계가공학회지
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• 제18권11호
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• pp.18-23
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• 2019

The oil immersion method can be used to create objective lenses with long working distances without sacrificing the focusing resolution for laser processing. In this study, a space in which air or oil can be filled was formed in the middle of a lens for analyzing the optical properties of a liquid-oil immersion lens. As the refractive media, air and oils of different refractive index values (1.2 and 1.5, respectively) were used. A simulation was conducted in the ZEMAX software environment using the ray-tracing technique, and the performance of the oil immersion lens was verified by determining its image distortion and focal length (FL) in each medium. In the case of air, the calculated FL was 0.813 mm, whereas the imaged FLs were 1.594 mm and 8.126 mm when the refraction indices were 1.2 and 1.5, respectively. The FL of an oil immersion lens could be increased considerably. In terms of image distortion, the oil immersion lens exhibited little distortion at the center in all cases, but different degrees of image distortion were observed at different points away from the center depending on the refraction index degree.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.58-62
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• 2019

Diffractive Optical Elements(DOEs) diffracts incident light using the diffraction phenomenon of light to generate a desired diffraction image. In recent years, the use of diffraction optics, which can replace existing refractive optical elements with flat plates, has been increased by implementing various optical functions that could not be implemented in refractive optical devices and by becoming miniaturized and compacted optical elements. Direct laser lithography is typically used to effectively fabrication such a diffractive optical element in a large area with a low process cost. In this study, the process conditions for fabricating patterns of diffractive optical elements in various shapes were found using direct laser lithographic system, and optical performance evaluation was performed through fabrication.

• Current Optics and Photonics
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• 제3권3호
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• pp.199-203
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• 2019

The characteristics of a photonic crystal fiber sensor with reuleaux triangle are studied by using the finite element method. The wavelength sensitivity of the designed optical fiber sensor is related to the arc radius of the reuleaux triangle. Whether the core area is solid or liquid as well as the refractive index of the liquid core contributes to wavelength sensitivity. The simulation results show that larger arc radius leads to higher sensitivity. The sensitivity can be improved by introducing a liquid core, and higher wavelength sensitivity can be achieved with a lower refractive index liquid core. In addition, the specific channel plated with gold film is polished and then analyte is deposited on the film surface, in which case the position of the resonance peak is the same as that of the complete photonic crystal fiber with three analyte channels being filled with analyte. This means that filling process becomes convenient with equivalent performance of designed sensor. The maximum wavelength sensitivity of the sensor is 10200 nm/RIU and the resolution is $9.8{\times}10^{-6}RIU$.

• 한국광학회지
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• 제31권6호
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• pp.314-320
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• 2020

적외선 영상 장비에 사용되는 광학계는 온도에 따른 굴절률의 변화가 심해 운용 온도 범위가 넓은 군용 적외선 영상장비에는 자동초점조절 기능이 필수적이다. 본 논문에서는 3중 배율의 적외선 영상 장비를 설계하고 해당 장비의 온도에 따른 굴절률 변화를 보상하기 위하여 온도 챔버에 영상 장비와 시준기를 설치하여 온도에 따른 렌즈 초점 이동량 변화를 측정하였다. 측정된 이동량을 활용하여 자동초점조절 기능을 구현하였으며 두 번의 온도 시험을 통해 -35~71℃의 넓은 운용 온도범위에서 상온의 MTF 성능과 동등한 수준의 분해능 성능의 영상을 확인하였다.

• Current Optics and Photonics
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• 제6권3호
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• pp.252-259
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• 2022

In this paper, a dual-function dynamically tunable metamaterial absorber is proposed. At frequency points of 1.545 THz and 3.21 THz, two resonance peaks with absorption amplitude of 93.8% (peak I) and 99.4% (peak II) can be achieved. By regulating the conductivity of photosensitive silicon with a pump laser, the resonance frequency of peak I switches to 1.525 THz, and that of peak II switches to 2.79 THz. By adjusting the incident polarization angle by rotating the device, absorption amplitude tuning is obtained. By introducing two degrees of regulation freedom, the absorption amplitude modulation and resonant frequency switching are simultaneously realized. More importantly, dynamic and continuous adjustment of the absorption amplitude is obtained at a fixed resonant frequency, and the modulation depth reaches 100% for both peaks. In addition, the sensing property of the proposed MMA was studied while it was used as a refractive index sensor. Compared with other results reported, our device not only has a dual-function tunable characteristic and the highest modulation depth, but also simultaneously possesses fine sensing performance.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.98-100
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• 2004

We report a novel manner for preparing single layer anti-reflective coatings with excellent optical properties (<1% reflection) over a broad wavelength regime. The technology is based upon the self-assembly and UV curing of reactive nano-particles, leading to nano-structured coatings with a gradient in refractive index. The single processing step leading to such coatings is fast, robust and cost effective. Furthermore in this paper we will address the mechanical durability of such nano-structured coatings.

• 한국항만학회지
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• 제15권1호
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• pp.99-105
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• 2001

An on-line refractrometer made of easily obtainable materials is built to determine the salinity and temperature of sea water, and its performance is examined by applying the refractometer to known salt solution. Since refractive index and temperature are measured simultaneously, it is possible to compensate the effect of temperature for accurate measurement. The outcome of salinity measurement for the different concentrations of salt solution indicates that the device is suitable for the salinity measurement by yielding stable and reproducible reading.

• 전자통신동향분석
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• 제35권3호
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• pp.9-19
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• 2020

Recently, a technique for applying a deep learning language model pretrained from a large corpus to fine-tuning for each application task has been widely used as a language processing technology. The pretrained language model shows higher performance and satisfactory generalization performance than existing methods. This paper introduces the major research trends related to deep learning pretrained language models in the field of language processing. We describe in detail the motivations, models, learning methods, and results of the BERT language model that had significant influence on subsequent studies. Subsequently, we introduce the results of language model studies after BERT, focusing on SpanBERT, RoBERTa, ALBERT, BART, and ELECTRA. Finally, we introduce the KorBERT pretrained language model, which shows satisfactory performance in Korean language. In addition, we introduce techniques on how to apply the pretrained language model to Korean (agglutinative) language, which consists of a combination of content and functional morphemes, unlike English (refractive) language whose endings change depending on the application.

• 약학회지
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• 제23권3_4호
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• pp.181-186
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• 1979

A high performance liquid chromatograpic procedure is described for determining ginseng saponins such as ginsenoside-Rb1, -Rb2, -Rc, -Rd, -Re, -Rf, -Rg1, and-Rg2. Ginseng saponins extracted with 90% methanol and water-saturated butanol were compared with pure standard ginsenosides. The resolution of the saponins was satisfactory and detection limit for each saponin was about 5.mu.g. Separation of the saponins was accomplished using a .mu. Bondapak carbohydrate analysis column, mobile phase of acetonitrile-water-butanol (80:20:15) and differential refractive index (RI) detector. The reproducibility and the recovery were also studied. This method was applied for determining the saponin contents of several parts of leaf, fresh ginseng, white ginseng, and red ginseng.