• Maxillofacial Plastic and Reconstructive Surgery
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• 제33권2호
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• pp.144-148
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• 2011

Purpose: The purpose of this study was to evaluate the effectiveness of a novel bone grafting material using an autogeneous tooth (AutoBT) and provide the basis for its clinical application. The AutoBT contains organic and inorganic mineral components and is prepared from autogenous grafting material, thus eliminating the risk of immune reactions that may lead to its rejection. AutoBT can be used as bone material as is has both osteoinduction and osteoconduction activities at guided bone regeneration for implant placement and maxillary sinus graft. Methods: In a total of 63 patients, guided bone regeneration surgery was performed at the time of implant placement, and tissue samples were harvested at the time of the second surgery with the patient's consent. Results: There were no complications in guided bone regeneration using autogeneous tooth. Conclusion: We concluded that AutoBT underwent gradual resorption and was replaced by new bone of excellent quality via osteoinduction and osteoconduction.

• 반도체디스플레이기술학회지
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• 제12권1호
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• pp.23-28
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• 2013

Epoxy resins are widely used in microelectronics packaging such as printed circuit board and encapsulating for semiconductor manufacturing. Water can diffuse into and through the epoxy matrix systems and moisture absorption at boarding interfaces of matrix resin systems can lead to a hydrolysis at the interfaces resulting in delamination of encapsulating materials. In the study, the changes of diffusion coefficient and moisture content ratio of epoxy resin systems with nano-sized fillers according to the change of liquid type epoxy resins were investigated. RE-304S, RE-310S, RE-810NM and HP-4032D as a epoxy resin, Kayahard AA as a hardener, and 1B2MI as a catalyst were used in these epoxy resin systems. After curing, moisture content ratios were measured with time under the 85 and 85% relative humidity condition using a thermo-hydrostat. The maximum moisture absorption ratio and diffusion coefficient of EMC decrease with the filler content. It can be seen that these decreases are due to the increase of filler surface area and the decrease of moisture through channel with the content of nano-sized filler.

• 대한지하수환경학회지
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• 제4권2호
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• pp.78-84
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• 1997

수도권 매립지 지반의 침출수에 대한 흡착성 분석을 위한 벳치실험과 컬럼시험을 수행하였다. 벳치실험에서는 제 1공구와 제 3공구 각각에서 채취한 지반토의 무기물, 중금속에 대한 흡착능과 흡착등온식을 알아보았으며 컬럼실험에서는 염소, 요오드, 칼륨, 납, 카드뮴을 사용하여 분산성과 오염 저감능력을 알아보았다. 시험결과 토양 시료 모두 Freundlich 등온식에 잘 따르는 것을 확인할 수 있었으며, 해성점토시료 모두 중금속과 무기물인 칼륨에 대한 흡착력이 큰 것으로 확인되었다. 시료 채취 지점의 지질변화에 따른 실험된 성분에 대한 흡착성의 차이는 거의 없는 것으로 나타났다.

• 환경위생공학
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• 제6권2호
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• pp.17-31
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• 1991

The effects of environmental agents on health are great concern for all. It was recognized that each human has differential susceptibility to environmental effects. Susceptibility are changed by many factors includin gdevelopmpntal processes, genetic factors, nutritional stratus, preexisting disease conditions, life style and personal habits. Of all factors nutritional factors seem to be the area most modifiable. Consequently, It is an area that must be more thoroughly evaluated. In this paper, nutrient and environment interactions are reviewed briefly with published literatures. This paper deals with the influence of micronutrients(energy, protein and fat), Vitamins (vitamin 4, vitamin B-complex, vitamin C, vitamin D and vitamin I) and Minerals(calcium, iron, selenium, zinc and other minerls) on environmental effects. The role of arch nutrient was assessed in modifyine the expression of environmental pollutant toxicity with available litertures. In each nutrient section, the effect of environment was considered in following agents : heavy metals(lead, cadmium, mercury, silver and etc), inorganic agents(nitwits, sulfite, fluoride and etc), organic agents(benzene, carbon tatra-chloride, aflatoxin, auto dye, dialbrin etc), Irritant gas(ozone, carbon monooxide and etc), physical agents(X-irradiation, ultra violet, temperature and noise) and insectcides. The extent to which nutritional status modifies environmental effects 3nd its converse, how envirollments affects nutritional status is very complex. In deed, at the present time there are more than 50 chelnical/phycical agents that affect the nutrient metabolism and/or have their toxicity either directly diminished or enhanced by nutrients of those agents, small number of agents for each nutrients have sufficient evidence to warrant any reasonable degree of confidence in their hypothesized associtation. With these information at this present time it is hard to conclude that the recommended dietary allowance for each nutrient should be reconsidered.

• Current Photovoltaic Research
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• 제8권2호
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• pp.60-65
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• 2020

In perovskite solar cells with planar heterojunction configuration, selection of proper charge-transporting layers is very important to achieve stable and efficient device. Here, we developed solution processible Cu doped NiO_x (Cu:NiO_x) thin film as a hole-transporting layer (HTL) in p-i-n structured methylammonium lead trihalide (MAPbI₃) perovskite solar cell. The transmittance and thickness of NiO_x HTL is optimized by control the spin-coating rate and Cu is additionally doped to improve the surface morphology of undoped NiO_x thin film and hole-extraction properties. Consequently, a perovskite solar cell containing Cu:NiO_x HTL with optimal doping ratio of Cu exhibits a power conversion efficiency of 14.6%.

• 한국지반공학회지:지반
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• 제13권4호
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• pp.75-84
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• 1997

본 논문은 해안 매립장의 해성점토와 그 기반 풍화토가 갖는 침출수 중의 무기물, 중금속 및 유기물에 대한 오염물 이동성 저감능력을 실내 주상실험에 의하여 조사하였다. 그 결과 무기물 인 칼릅의 경우 해성점토층의 흡착능이 하부 풍화토에 비하여 큰 것으로 나타났으며 중금속인 납과 카드윰의 경우는 매립장 실제 배출 농도보다 큰 농도에서도 완전 흡착되는 것으로 나타났다. 유기성 폐기물에 대한 실험결과 그 흡착능이 무기물이나 중금속에 비하여는 떨어지나 침출수내의 난분해성 유기물질을 기반 점토 및 풍화토가 저감시킬 수 있는 것으로 나타났다.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1739-1744
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• 2008

본 연구에서는 현재 국내에서 다량 사용하고 있는 중금속 크롬($Cr^{6+}$)과 납(Pb)이 포함된 녹색안료를 대체하기 위하여 유동층기상증착(FB-VD) 공정을 사용한 무독성 유 무기 복합안료를 개발하였다. 안교제조를 위하여 카올린(Kaolin) 계열의 화합물과 탄산칼슘($CaCO_3$)을 담체로 사용하였으며, 담체들의 표면특성과 구성성분은 SEM과 EDXS를 사용하여 고찰하였다. 또한 안료의 성능을 극대화하기 위하여 다양한 종류의 계면활성제를 사용하고, 그 성능 차이를 고찰하였다. 녹색안료의 색상발현 실험을 한 결과 건조상태나 색상발현에서 녹색물실 배합농도에 차이를 보였으나, 음이온 계면활성제를 사용한 경우 건조와 색상발현에 가장 적합하였다.

• Bulletin of the Korean Chemical Society
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• 제11권2호
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• pp.109-114
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• 1990

The anionic transition metal hydrides $(HW(CO)_4P(OMe)_3\;^-,\;HW(CO)_5\;^-,\;HCr(CO)_5\;^-,\;HFe(CO)_4\;^-)$ react with transition metal alkyl $(CpMo(CO)_3(CH_3)$ to yield $CH_4\;and\;CH_3CHO$ in addition to the inorganic products $(CpMo(Co)_3\;^-$, etc.). The reaction of these anionic metal hydrides with CpMo(CO)3{CH2CH(CH2)2} may lead to an elucidation of the reaction mechanisms involved; the organic product distributions are among $CH_4,\;CH_2\;=\;CHCH_2CH_3$, and $CH_3CH(CH_2)_2$, depending upon the anionic metal hydride used. These anionic metal hydrides also are reported to undergo a hydride-halide exchange reaction with organic halides; therefore, these similar reactions have been compared in terms of leaving group ability $(CpMo(CO)_3\;^-\;vs.\;Br^-)$ and the mechanistic pathways.

• 한국표면공학회지
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• 제54권5호
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• pp.207-212
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• 2021

The mechanical and electrical characteristics can be improved in 3D stacked IC technology which can accomplish the ultra-high integration by stacking more semiconductor chips within the limited package area through the Cu direct bonding method minimizing the performance degradation to the bonding surface to the inorganic compound or the oxide film etc. The surface was treated in a ultrasonic washer using a diamond abrasive to remove other component substances from the prepared cast plate substrate surface. FE-SEM was used to analyze the bonding characteristics of the bonded copper substrates, and the cross section of the bonded Cu conjugates at the sintering junction temperature of 100 ℃, 150 ℃, 200 ℃, 350 ℃ and the pressure of 2303 N/cm² and 3087 N/cm². At 2303 N/cm², the good bonding of copper substrate was confirmed at 350 ℃, and at the increased pressure of 3087 N/cm², the bonding condition of Cu was confirmed at low temperature junction temperature of 200 ℃. However, the recrystallization of Cu particles was observed due to increased pressure of 3087 N/cm² and diffusion of Cu atoms at high temperature of 350 ℃, which can lead to degradation in semiconductor manufacturing.

• 한국재료학회지
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• 제31권9호
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• pp.496-501
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• 2021

Metal halide perovskite nanocrystals, due to their high absorption coefficient, high diffusion length, and photoluminescence quantum yield, have received significant attention in the fields of optoelectronic applications such as highly efficient photovoltaic cells and narrow-line-width light emitting diodes. Their energy band structure can be controlled via chemical exchange of the halide anion or monovalent cations in the perovskite nanocrystals. Recently, it has been demonstrated that chemical exfoliation of the halide perovskite crystal structure can be achieved by addition of organic ligands such as n-octylamine during the synthetic process. In this study, we systematically investigated the quantum confinement effect of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanocrystals by precise control of the crystal thickness via chemical exfoliation using n-octylammonium bromide (OABr). We found that the crystalline thickness consistently decreases with increasing amounts of OABr, which has a larger ionic radius than that of CH₃NH₃⁺ ions. In particular, a significant quantum confinement effect is observed when the amounts of OABr are higher than 60 %, which exhibited a blue-shifted PL emission (~ 100 nm) as well as an increase of energy bandgap (~ 1.53 eV).