• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.433-436
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• 2018

A total internal reflection (TIR) linear lens of size $190(W){\times}5(D){\times}2.1(H)mm^3$ has a directivity of $25^{\circ}$ and was made of a polydimethysiloxane (PDMS) silicone resin with a refractive index of 1.4 and a transmittance of 93% at 365 nm UV wavelength. A light source with a size of $190{\times}25.5mm^2$ was fabricated by installing a TIR linear lens on a chip on board (COB) type LED module mounted with a $1.1{\times}1.1mm^2$ size UV LED. The optical characteristics of the light source showed a maximum irradiation density of $3,840mW/cm^2$ at a working distance of 5 mm and a high uniformity of 91.6% over a $150{\times}25mm^2$ irradiation area. The thermal characteristics of the light source were measured at a supply current of 500 mA. The saturation temperature was reached after 30 min of operation, and measured to be $95^{\circ}C$.

• 통합자연과학논문집
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• 제9권1호
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• pp.16-22
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• 2016

The optical and physical and characteristics of hydrogel ophthalmic lens polymerized with addition of 2,6-difluoropyridine, SiPc(silicon 2,9,16,23-tetra-tert-butyl-29H31H-phthalocyanine dihydroxide) and nanodiamond in the basic hydrogel material were evaluated. In particular, the utility of 2,6-difluoropyridine, SiPc and nanodiamond as a hydrogel ophthalmic lens material was investigated. 2,6-difluoropyridine, SiPc and nanodiamond were used as additives. And also, 2-hydroxyethyl methacrylate, acrylic acid, methyl methacrylate and a cross-linker EGDMA were copolymerized in the presence of AIBN as an initiator. The refractive index of 1.4348~1.4361, water content of 33.30~34.02%, UV-B transmittance of 4.77~67.50%, UV-A transmittance of 1.45~89.19% and visible transmittance of 32.12~92.21% were obtained. The results of hydrogel lens containing 2,6-difluoropyridine (add 5%) showed antibiosis for staphylococcus aureus. The produced copolymer is suitable for hydrogel soft ophthalmic lenses with antibiotic and anti-UV effect.

• Journal of Ceramic Processing Research
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• 제20권spc1호
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• pp.86-91
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• 2019

A solid-state route was used to prepare sodium titanium oxide (NTO, Na2Ti3O7) as a solar heat protecting material with an impressive solar reflectance (TSR = 94.3%) using a high refractive index rutile TiO2. The solar reflectance of the synthesized NTO was measured using UV-Vis-NIR spectrophotometer. Solar reflectance property of the synthesized compound depends on the calcination temperature. The solar reflectance property of the synthesized NTO powder was compared with commercial rutile TiO2. The compound synthesized at 900 ℃ for 24 hrs had remarkable solar reflectance 94.3% than that calcined below 900 ℃. Crystalline nature, structural property, morphology and optical properties of NTO powders were characterized and analyzed using XRD, FE-SEM, EDS and UV-Vis-NIR spectrophotometer. From the results, we guessed that NTO would be a suitable "solar heat protecting candidate" for energy-saving applications in coating industries.

• 반도체디스플레이기술학회지
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• 제21권3호
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• pp.119-124
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• 2022

Top emission organic light-emitting diode (TEOLED) is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device (BEOLED). Unlike BEOLED, TEOLED contain semitransparent metal cathode and capping layer. Because there are many characteristics to consider just simple thickness change, optimizing organic thickness of TEOLED for microcavity is difficult. So, in this study, we optimized Device capping layer at unoptimized micro-cavity structure TEOLED device. And we compare only capping layer with unoptimized microcavity structure can overcome optimized micro-cavity structure device. We used previous our optimized micro-cavity structure to compare each other. As a result, it has been found that the efficiency can be obtained almost the same or higher only capping layer, which is stacked on top of the device and controls only the thickness and refractive index, without complicated structural calculations. This means that higher efficiencies can be obtained more easily in laboratories with limited organic materials or when optimizing new structures etc.

• 한국재료학회지
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• 제33권1호
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• pp.1-7
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• 2023

The physical and antibacterial properties of ophthalmic lenses fabricated by copolymerization with hydrogel monomers using two types of graphene were measured, and their usability as contact lens materials was analyzed. For polymerization, silicone monomers, including SID-OH, 3-(methacryloxy)propyl tris(trimethylsiloxy)silane, and decamethylcyclopentasiloxane, were used, and N,N-dimethylacetamide, ethylene glycol dimethacrylate as a crosslinking agent, and azobisisobutyronitrile as an initiator were added. Also, graphene oxide nanoparticle (GON) and graphene nanoplate (GNP) were used as an additive, and the physical properties of the lenses fabricated after copolymerization were evaluated. The fabricated lenses satisfied the basic physical properties of general hydrogel contact lenses and showed the characteristics of lenses with high water content, and the disadvantage of very weak durability, due to low tensile strength. However, it was confirmed that the tensile strength and antibacterial properties were greatly improved by adding GON and GNP. With GON, the oxygen permeability and refractive index of the fabricated lenses were slightly improved. Therefore, it was determined that the graphene materials used in this study can be used in various ways as a contact lens material.

• 비파괴검사학회지
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• 제25권5호
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• pp.339-342
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• 2005

광섬유 센서 구성을 위한 장주기 광섬유 격자(Long-Period Fiber Grating, LPFG)는 코어 모드로 진행하는 빔이 위상 정합 조건(Phase Matching Condition)에 의해 특정 파장에서 클래딩 모드와 커플링이 일어나는 광소자이다. 공진 파장과 커플링의 세기는 온도, 스트레인, 주변 굴절 지수 등에 의해 민감하게 변화하는 특성을 이용하여 광섬유 센서에 넓게 응응될 수 있다 일반적으로 광섬유 격자는 광섬유 코어를 자외선에 노출시킴으로서 굴절률의 주기적인 변화가 유도되는 원리, 즉 광민감성 (Photosensitivity)에 기초를 두고 있으며 광민감성을 가진 격자제조용 광섬유 제작은 광섬유 격자 연구에 대단히 중요한 부분이다. 이 논문에서는 보론 첨가의 양에 의한 코어와 클래딩의 굴절률 차 변화와 그것에 따른 장주기 광섬유 격자의 온도 및 구부림 특성 변화를 분석하였다. 보론의 양이 증가할수록 코어와 클래딩의 굴절률 차가 줄어드는 것$(1.69{\times}10^{-4}/SCCM)$을 실험을 통해 알 수 있었고, 그로 인해 보론의 음의 온도 의존성으로 인해 장주기 광섬유 격자의 온도 의존성이 억제됨$(0.01145nm/^{\circ}C/SCCM)$을 확인할 수 있었다. 또한, 보론의 증가로 인해 코어와 클래딩의 굴절률차가 줄어들수록 장주기 광섬유 격자는 구부림에 더 민감함을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.267-271
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• 2018

A high directivity TIR (total internal reflection) lens in the UV-A region was designed using a silicone resin, and a UV light source module with a maximum irradiation density of $150mW/cm^2$ was fabricated. The beam angle of the TIR lens was designed to be $8.04^{\circ}$ and the maximum diameter of the TIR lens was Ø13.5. A silicone resin having a UV transmittance of 93% and a refractive index of 1.4 at a wavelength of 365 nm was used, and the lens was manufactured using an aluminum mold, from which silicone could be easily released. The module was fabricated in a metal printed circuit board of COB (chip on board) type using a $0.75{\times}0.75mm^2$ UV chip. A jig was used to adjust the focal length between lens and chip and to fix the position of the lens. The optical characteristics such as illumination distributions of the lens and module were designed using 'LightTools' optical simulation software. The heat dissipation system was designed to use a forced-air cooling method using a heat-sink and fan.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.83-87
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• 2002

Plasma enhanced chemical vapor deposited (PECVD) silicon nitride ($SiN_X$) is widely used as a gate dielectric material for the hydrogenated amorphous silicon(a-Si:H) thin film transistors (TFT's). We investigated $SiN_X$ films were deposited PECVD at low temperature ($300^{\circ}C$). The reaction gases were used pure nitrogen and a helium diluted of silane gas(20% $SiH_4$, 80% He). Experimental investigations were carried out with the variation of $N_2/SiH_4$ flow ratios from 3 to 50 and the rf power of 200 W. This article presents the $SiN_X$ gate dielectric studies in terms of deposition rate, hydrogen content, etch rate and C-V, leakage current density characteristics for the gate dielectric layer of thin film transistor applications. Electrical properties were analyzed through high frequency (1MHz) C-V and current-voltage (I-V) measurements. The thickness and the refractive index on the films were measured by ellipsometry and chemical bonds were determined by using an FT-IR equipment.

• 문화기술의 융합
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• 제6권4호
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• pp.727-732
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• 2020

본 연구에서는 1.55um의 파장을 갖는 DFB 레이저에서 굴절률 격자와 이득 격자가 동시에 존재할 때, 오른쪽 거울 면에 반사가 일어나지 않도록 유전막 코팅을 하여 𝜌_r=0 이 되도록 하였다. δL > 0인 경우일 때, 문턱에서 발진 모드에 대하여, 발진 이득과 종 방향으로의 발진 모드의 빔 분포와 방사전력비 P_l/P_r를 𝜌_l의 위상=π인 경우와 𝜌_l의 위상=π/2인 경우에 대하여 비교했다. 𝜌_l의 위상=π인 경우, 낮은 문턱 전류와 높은 주파수 안정성을 얻기 위해서는, κL이 8보다 커야 한다. 𝜌_l의 위상=π/2인 경우, κL = 4보다 커지면서 𝜌_l의 위상=π인 경우보다 발진 이득이 낮아지기 시작함을 볼 수 있고, 발진 모드의 문턱 전류를 낮추고 주파수 안정성을 높이기 위해서는, κL이 8보다 커야한다.

• 한국전기전자재료학회논문지
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• 제30권6호
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• pp.387-392
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• 2017

A high-performing all-transparent photodetector was created by configuring a $MoO_x$/NiO/ZnO/ITO structure on a glass substrate. The ITO bottom layer was applied as a back contact. To achieve the transparent p/n junction, p-type NiO was coated on the n-type ZnO layer. Reactive sputtering was used to spontaneously form the ZnO or NiO layer. In order to improve the transparent photodetector performance, the functional $MoO_x$ window layer was used. Optically, the $MoO_x$ window provided a refractive index layer (n=1.39) lower than that of NiO (n=2), increasing the absorption of the incident light wavelengths (${\lambda}s$). Moreover, the $MoO_x$ window can provide a lower sheet resistance to improve the carrier collection for the photoresponses. The $MoO_x$/NiO/ZnO/ITO device showed significantly better photoresponses of 877.05 (at ${\lambda}$=460nm), 87.30 (${\lambda}$=520 nm), and 30.38 (${\lambda}$=620 nm), compared to 197.28 (${\lambda}$=460 nm), 51.74 (${\lambda}$=520 nm) and 25.30 (${\lambda}$=620 nm) of the NiO/ZnO/ITO device. We demonstrated the high-performing transparent photodetector by using the multifunctional $MoO_x$ window layer.