• 콘크리트학회논문집
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• 제23권5호
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• pp.647-656
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• 2011

방사성 폐기물 처분 시설과 같은 지하 구조물의 콘크리트 부재가 장기간에 걸쳐 지하수(이온교환수)와 접촉하면 이온교환수와 공극수 사이에 농도구배가 발생한다. 이로 인해 공극수로부터 칼슘이온이 용출되고, 콘크리트의 열화가 진행된다. 따라서 이 연구에서는 콘크리트의 칼슘 용출에 의한 내부공극 구조의 변화를 분석하고, 열화된 콘크리트의 강도 특성을 평가하고자 하였다. 연구 결과, 콘크리트의 칼슘이온이 용출됨에 따라 50~500 nm 크기의 공극들이 상당히 증가하게 되며, 용출 초기에는 200 nm 크기 이상의 공극들이 급격히 증가하고 이후에는 200 nm 크기 이하의 공극들이 증가하는 것으로 나타났다. 칼슘이 용출된 두께가 증가함과 더불어 압축강도는 감소하였으며, 칼슘이 용출된 OPC 콘크리트의 잔류강도는 대략 33~58% 정도로 나타났다.

• 한국재료학회지
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• 제23권9호
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• pp.489-494
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• 2013

In this study, by using nickel chloride solution as a raw material, a nano-sized nickel oxide powder with an average particle size below 50 nm was produced by spray pyrolysis reaction. A spray pyrolysis system was specially designed and built for this study. The influence of nozzle tip size on the properties of the produced powder was examined. When the nozzle tip size was 1 mm, the particle size distribution was more uniform than when other nozzle tip sizes were used and the average particle size of the powder was about 15 nm. When the nozzle tip size increases to 2 mm, the average particle size increases to roughly 20 nm, and the particle size distribution becomes more uneven. When the tip size increases to 3 mm, particles with an average size of 25 nm and equal to or less than 10 nm coexist and the particle size distribution becomes much more uneven. When the tip size increases to 5 mm, large particles with average size of 50 nm partially exist, mostly consisting of minute particles with average sizes in the range of 15~25 nm. When the tip size increases from 1 mm to 2 mm, the XRD peak intensities greatly increase while the specific surface area decreases. When the tip size increases to 3 mm, the XRD peak intensities decrease while the specific surface area increases. When the tip size increases to 5 mm, the XRD peak intensities increase again while the specific surface area decreases.

• 열처리공학회지
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• 제27권1호
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• pp.23-26
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• 2014

Ga doped ZnO (GZO) single layer and GZO/ZnO bi-layered films were deposited on glass substrates by radio frequency magnetron sputtering and then the influence of film thickness on the structural, electrical, and optical properties of the films was considered. Thicknesses of the GZO/ZnO films was varied as GZO 100 nm, GZO 85 nm/ZnO 15 nm and GZO 70 nm/ZnO 30 nm, respectively. The observed result means that optical transmittance and electrical resistivity of the films were influenced with film thickness and GZO 85 nm/ZnO 15 nm bilayered films show the higher figure of merit than that of the films prepared other films in this study.

• 한국재료학회지
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• 제23권8호
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• pp.469-475
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• 2013

Al-doped ZnO(AZO) thin films were synthesized using atomid layer deposition(ALD), which acurately controlled the uniform film thickness of the AZO thin films. To investigate the electrical and optical properites of the AZO thin films, AZO films using ALD was controlled to be three different thicknesses (50 nm, 100 nm, and 150 nm). The structural, chemical, electrical, and optical properties of the AZO thin films were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, field-emssion scanning electron microscopy, atomic force microscopy, Hall measurement system, and UV-Vis spectrophotometry. As the thickness of the AZO thin films increased, the crystallinity of the AZO thin films gradually increased, and the surface morphology of the AZO thin films were transformed from a porous structure to a dense structure. The average surface roughnesses of the samples using atomic force microscopy were ~3.01 nm, ~2.89 nm, and ~2.44 nm, respectively. As the thickness of the AZO filmsincreased, the surface roughness decreased gradually. These results affect the electrical and optical properties of AZO thin films. Therefore, the thickest AZO thin films with 150 nm exhibited excellent resistivity (${\sim}7.00{\times}10^{-4}{\Omega}{\cdot}cm$), high transmittance (~83.2 %), and the best FOM ($5.71{\times}10^{-3}{\Omega}^{-1}$). AZO thin films fabricated using ALD may be used as a promising cadidate of TCO materials for optoelectronic applications.

• 한국재료학회지
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• 제23권6호
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• pp.334-338
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• 2013

In this study, $BaTiO_3$ thin films were grown by RF-magnetron sputtering, and the effects of the thin film thickness on the structural characteristics of $BaTiO_3$ thin films were systematically investigated. Instead of the oxide substrates generally used for the growth of $BaTiO_3$ thin films, p-Si substrates which are widely used in the current semiconductor processing, were used in this study in order to pursue high efficiency in device integration processing. For the crystallization of the grown thin films, annealing was carried out in air, and the annealing temperature was varied from $700^{\circ}C$. The changed thickness was within 200 nm~1200 nm. The XRD results showed that the best crystal quality was obtained for ample thicknesses 700 nm~1200 nm. The SEM analysis revealed that Si/$BaTiO_3$ are good quality interface characteristics within 300 nm when observed thickness. And surface roughness observed of $BaTiO_3$ thin films from AFM measurement are good quality surface characteristics within 300 nm. Depth-profiling analysis through GDS (glow discharge spectrometer) showed that the stoichiometric composition could be maintained. The results obtained in this study clearly revealed $BaTiO_3$ thin films grown on a p-Si substrate such as thin film thickness. The optimum thickness was 300 nm, the thin film was found to have the characteristics of thin film with good electrical properties.

• 한국재료학회지
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• 제23권6호
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• pp.304-308
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• 2013

The effect of a sputter deposition sequence of Cu, Zn, and Sn metal layers on the properties of $Cu_2ZnSnS_4$ (CZTS) was systematically studied for solar cell applications. The set of Cu/Sn/Zn/Cu multi metal films was deposited on a Mo/$SiO_2$/Si wafer using dc sputtering. CZTS films were prepared through a sulfurization process of the Cu/Sn/Zn/Cu metal layers at $500^{\circ}C$ in a $H_2S$ gas environment. $H_2S$ (0.1%) gas of 200 standard cubic centimeters per minute was supplied in the cold-wall sulfurization reactor. The metal film prepared by one-cycle deposition of Cu(360 nm)/Sn(400 nm)/Zn(400 nm)/Cu(440 nm) had a relatively rough surface due to a well-developed columnar structure growth. A dense and smooth metal surface was achieved for two- or three-cycle deposition of Cu/Sn/Zn/Cu, in which each metal layer thickness was decreased to 200 nm. Moreover, the three-cycle deposition sample showed the best CZTS kesterite structures after 5 hr sulfurization treatment. The two- and three-cycle Cu/Sn/Zn/Cu samples showed high-efficient photoluminescence (PL) spectra after a 3 hr sulfurization treatment, wheres the one-cycle sample yielded poor PL efficiency. The PL spectra of the three-cycle sample showed a broad peak in the range of 700-1000 nm, peaked at 870 nm (1.425 eV). This result is in good agreement with the reported bandgap energy of CZTS.

• 한국재료학회지
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• 제23권1호
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• pp.47-52
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• 2013

Graphene has been synthesized on 100- and 300-nm-thick Ni/$SiO_2$/Si substrates with $CH_4$ gas (1 SCCM) diluted in mixed gases of 10% $H_2$ and 90% Ar (99 SCCM) at $900^{\circ}C$ by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on $SiO_2$/Si substrate after heat treatment at $900^{\circ}C$ for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/$SiO_2$/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/$SiO_2$/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/$SiO_2$/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and $47cm^{-1}$, respectively. The several-layer graphene showed a low sheet resistance value of $718{\Omega}/sq$ and a high light transmittance of 87% at 550 nm.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.701-708
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• 2020

In this paper, we analyzed the optical properties of the LED module for dental care, which has the effect of promoting cell regeneration and scar treatment. The LED module is a U-shaped module suitable for the shape of teeth. It is manufactured with an LED module (632 nm) and an LED module (632 nm + 870 nm), analyzes the results of optical properties, sets the irradiation distance, irradiation time, and is effective in healing skin wounds. Evaluation was conducted. It was tested in 6 test groups according to the light irradiation conditions, and light was irradiated to the scar site every other day for 7 days, 1 day and 3 days. As a result, it was confirmed that the effect of scar treatment was the highest when the combined wavelength of 632 nm + 870 nm was irradiated in pulse mode than when the single wavelength was irradiated and the composite wavelength was continuously irradiated. In group C group irradiated with PW Mode: pulse mode (period 36 ms, pulse width 35 ms) using a composite wavelength with LED module (632 nm + 870 nm) than group A without light irradiation, the length of scar reduction was 19 %, the area of the scar was further reduced by 10%, and it was confirmed that it is effective in treating scars in the wound area.

• 한국수산과학회지
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• 제19권3호
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• pp.234-240
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• 1986

일본 동경만내에서의 해수의 광학적 성질을 조사하기 위하여, 1985년 4월에 동경만내의 6개 관측점에서 투명도, 수색, 태양고도, 태양광의 8가지 파장(378, 422, 481, 513, 570, 621, 653, 677 nm)에 대한 해수의 표면조도 및 수중조도 등을 조사한 결과를 요약하면 다음과 같다. 1. 본 조사해역의 투명도는 5.0m ($2.5{\sim}6.5m$)였고, 수색은 10.2 ($8{\sim}14$)였다. 2. 해수의 평균소산계수는 0.335 ($0.081{\sim}0.862$)였고, 파장별로는 677nm가 0.464, 653nm가 0.425, 621nm가 0.356, 422nm가 0.354, 570nm가 0.284, 481nm가 0.274, 378nm가 0.268, 513nm가 0.256순으로 작게 나타났다. 3. 해수의 소산계수 K와 투명도 D와의 관계는 K=2.22/D ($1.3/D{\sim}3.54/D$)였다. 4. 태양고도는 $53.62^{\circ}$ ($38.54^{\circ}{\sim}66.23^{\circ}$)로 나타났다. 5. 태양광선의 표면광에 대한 평균해중투과율은 수심 1m 층에서 $62.72\%$, 5m 층에서 $11.91\%$, 10m 층에서 $2.64\%$, 20m 층에서 $0.50\%$로 나타났다. 6. 투명도층에서의 태양광선의 해중투과율은 표면광의 $12.51\%$ ($2.91{\sim}27.25\%$)였고, 677nm의 광이 $5.97\%$로서 가장 적었으며 570nm의 광이 $20.22\%$로서 가장 많았다.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.260-263
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• 1990

We report the operation of an Nd+3 doped silica single mode fiber laser pumped by a 514.5nm Ar laser. A CW output power in excess of 0.27mW at 1.096um has been obtained with a sloped efficiency of 0.23% and a 15nm badnwidth.