• 한국물환경학회지
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• 제31권5호
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• pp.563-568
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• 2015

Natural Organic Matter (NOM) is a precursor of disinfection by products. Recently, with the increase in NOM concentration caused by a large amount of algae, the creation of disinfection by-products is becoming a big issue. Therefore, in this study, PAC+Membrane+F/A hybrid process was organized to control disinfection by-products in small-scale water treatment plants. The optimal dosage of PAC was set at 20 mg/L through Lab. scale test. Also, it is judged that NOM concentration must be less than 1.0 mg/L to meet the recommended criteria of drinking water quality monitoring items of disinfection by-products during chlorination. The existing conventional water treatment process was compared to the independent F/A process and the PAC+Membrane+F/A hybrid process through pilot plant operation, and the result showed that there is a need to apply an advanced water treatment process to remove not only NOMs but also Geosmin caused by algae. Accordingly, it is considered that applying the PAC+Membrane+F/A process will help in controling a clogged filter caused by a large amount of algae and disinfection by-products created by chlorination and can be used as an advanced water treatment process to meet the recommended criteria of drinking water quality monitoring items.

• 접착 및 계면
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• 제20권4호
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• pp.146-154
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• 2019

본 연구에서는 소수성 PPO 사슬과 친수성 PEO 사슬들이 동시에 존재하고, 반응성 알콕시 실란기를 가지고 있는 알콕시 실란 기능화 양친성 고분자 전구체 (Alkoxysilane-functionalized Amphiphilic Polymer, AFAP)를 합성하여, 이를 TEOS과의 Hydrolysis- Polycondensation 반응에서 분산안정제 및 반응속도 조절제로 이용하여서 유-무기 하이브리드 나노입자가 안정적으로 분산된 졸 (Sol)을 제조하였다. 제조된 Sol에 불소 함유 실란화합물을 혼합·반응하여서 불소함유 유-무기 하이브리드 Sol을 제조하였고, 이를 유리 기재에 코팅하고 저온 경화를 통해 기재위에 경화필름을 형성하였다. 형성된 경화 필름은 AFAP 및 불소 함유 실란화합물의 첨가량, 용매 종류에 따라서 표면 경도 및 발수 특성이 변화하였다. 최적의 용매 및 불소 함유 실란화합물 첨가량에서 태양전지나 디스플레이에 적용가능한 투명하면서도 견고한 유-무기 하이브리드 형태의 코팅필름 형성이 가능하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.252.2-252.2
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• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

• 한국추진공학회지
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• 제23권5호
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• pp.36-42
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• 2019

본 연구에서는 리오셀 섬유를 사용하여 탄소직물을 제조함에 있어, 인계 난연제인 Phosphoric Acid(PA)와 가교제인 Melamine resin (MR)을 사용하여 섬유의 전처리를 수행하고 TGA, FT-IR, XRD, 중량 분석을 통하여 물리적, 화학적 구조 변화에 대하여 고찰하였다. 전처리를 통하여 내염화 및 흑연화된 직물의 경우 미처리 직물과 비교하여 중량 수율이 14.7%, 직물 폭과 길이의 수율이 각각 15%, 15.5% 증가함을 확인하였다. 이러한 결과는 셀룰로오스의 탈수반응을 촉진과 함께 섬유 표면에 char를 형성하고, 셀룰로오스 분자 내의 가교반응을 유도하여 내염화 시 안정한 구조 형성에 의한 효과로 설명할 수 있다.

• 한국환경과학회지
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• 제30권10호
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• pp.845-861
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• 2021

This study investigated the variations in monthly PM_2.5 concentrations and their characteristics at the sampling site (35.075°N, 129.080°E) around the Busan seaport area for six months (from August 2020 to January 2021). Monthly PM_2.5 concentrations in the filtered samples ranged from 8.4 to 42.3 ㎍/m³ (average=19.6±8.2 ㎍/m³, n=50) and were generally high in August, December, and January, and low in September, October, and November. The variations of monthly PM_2.5 concentrations showed similar patterns to those of the neighboring national air quality monitoring sites. The contents of Total Carbon (TC), Organic Carbon (OC), Elemental Carbon (EC), and OC/EC ratios in PM_2.5 showed large variability during the study period. The OC/EC ratios ranged from 4.2 to 34.4, suggesting that the relative contributions of OC and EC to the PM_2.5 concentrations changed temporally and might be related to their formation sources. Variations in the chemical components of and particle size distributions in PM_2.5 showed that high PM_2.5 concentrations were affected by various sources, such as sea salt and ship emission. The precursor gas concentrations were discussed in terms of monthly variations and their contributions to PM_2.5 concentrations. However, further research is needed to understand the characteristics and behaviors of PM_2.5 concentrations around the Busan seaport area.

• 한국유기농업학회지
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• 제28권4호
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• pp.579-589
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• 2020

고추역병 다발생 포장에서 녹비작물인 호밀재배에 따른 토양환경 변화와 고추역병 경감 효과를 조사하였다. 토양 물리성을 분석한 결과에서는 호밀재배에서 용적밀도와 공극률이 증가하였다. 또한, 토양 삼상의 분포는 고상에서는 관행재배와 차이가 없었으나, 기상은 관행재배 보다 증가하고 액상은 감소하였다. 토양 내 인지질 지방산을 추출하여 지표 지방산으로 분석한 미생물 군락의 상대밀도는 호밀재배에서 유의성 있게 증가하였으며, 호기성균/혐기성균의 비율의 비율도 호밀재배에서 높게 나타났다. 환경스트레스 지표인 포화지방산/불포화지방산 비율과 cyclo-지방산/전구체 비율은 호밀재배가 관행재배 보다 낮아 토양환경이 개선 된 것으로 나타났다. 호밀재배에 따른 고추역병의 경감효과를 조사한 결과 호밀재배가 관행재배 보다 30.7% 낮은 발병률을 나타냈다. 이상의 결과를 요약해볼 때, 고추역병 다발생 포장에서 녹비작물인 호밀재배는 토양환경을 개선하고 고추역병 발병을 감소시킬 것으로 사료된다.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.67-70
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• 2022

In order to prevent water vapor and oxygen permeation in the organic light emitting diodes (OLED), Al₂O₃ thin-film encapsulation (TFE) technology were investigated. Atomic layer deposition (ALD) method was used for making the Al₂O₃ TFE layer because it has superior barrier performance with advantages of excellent uniformity over large scales at relatively low deposition temperatures. In this study, the thickness of the Al₂O₃ layer was varied by controlling the numbers of the unit pulse cycle including Tri Methyl Aluminum(Al(CH₃)₃) injection, Ar purge, and H₂O injection. In this case, several process parameters such as injection pulse times, Ar flow rate, precursor temperature, and substrate temperatures were fixed for analysis of the effect only on the thickness of the Al₂O₃ layer. As results, at least the thickness of 39 nm was required in order to obtain the minimum WVTR of 9.04 mg/m²day per one Al₂O₃ layer and a good transmittance of 90.94 % at 550 nm wavelength.

• Journal of information and communication convergence engineering
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• 제1권3호
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• pp.133-138
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• 2003

The preparation of $Al_{2}O_{3}-SiO_{2}$ thin films from less than one micron to several tens of microns in thickness had been prepared from metal alkoxide sols. Two methods, dip-withdrawal and electrophoretic deposition, were employed for thin films and sheets formation. The requirements to be satisfied by the solution for preparing uniform and strong films and by the factors affecting thickness and other properties of the films were examined. For the preparation of thin, continuous $Al_{2}O_{3}-SiO_{2}$ films, therefore, metal-organic-derived precursor solutions contained Si and Al in a chemically polymerized form has been developed and produced in a clear liquid state. In the process of applying to substrates, this liquid left a transparent, continuous film that could be converted to crystalline $Al_{2}O_{3}-SiO_{2}$ upon heating to $1000^{\circ}C$. And, a significant change of the film density took place in the crystallization process, thus leading to the strict requirements as to the film thickness, which could survive crystallization.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1252-1256
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• 2010

A polyvinylpyrrolidone (PVP)/Ag nanocomposites was prepared by the simultaneous thermal reduction and radical polymerization route. The in situ synthesis of the Ag/PVP nanocomposites is based on the finding that the silver n-propylcarbamate (Ag-PCB) complex can be directly dissolved in the NVP monomer, and decomposed by only heat treatment in the range of 110 to $130^{\circ}C$ to form silver metal. Silver nanoparticles with a narrow size distribution (5 - 40 nm) were obtained, which were well dispersed in the PVP matrix. A successful synthesis of Ag/PVP nanocomposites then proceeded upon heat treatment as low as $110^{\circ}C$. Moreover, important advantages of the in situ synthesis of Ag/PVP composites include that no additives (e.g. solvent, surface-active agent, or reductant of metallic ions) are used, and that the stable silver nanocolloid solution can be directly prepared in high concentration simply by dissolving the Ag/PVP nanocomposites in water or organic solvent.

• 센서학회지
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• 제21권6호
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• pp.446-450
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• 2012

The important factors in sensors are sensitivity, selectivity, and response time. Oxide semiconductors are high sensitivity, fast response and the advantage of miniaturization. Zn-doped $SnO_2$ materials have been synthesized in order to improve the selectivity of the sensor. ZnO/$SnO_2$ crystals were prepared by a simple hydrothermal process and ultrasound pretreated hydrothermal process. ZnO/$SnO_2$ urchins were fabricated in the precursor solution with [$Zn^{2+}$]:[$Sn^{4+}$] ratio of 1:5 and rod structures were fabricated ratio of 1:1 and 1:3. Surface area ratio was increased by increasing the ratio of [$Sn^{4+}$]. The sensitivity of sensors were highest at the [$Zn^{2+}$]:[$Sn^{4+}$] ratio of 1:5 in ethanol, acetaldehyde, toluene, and nitric oxide.