• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.36-44
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• 2023

Core-shell TiO₂/Ag nanoparticles were synthesized by a modified sol-gel process and the reverse micelle method using acetoxime as a reducing agent in water/dodecylbenzenesulfonic acid (DDBA)/cyclohexane. The structure, shape, and size of the TiO₂/Ag nanoparticles were investigated using X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), and thermogravimetric analysis (TGA). The size of TiO₂/Ag nanoparticles could be controlled by changing the [water]/[DDBA] molar ratio values. The size and the polydispersity of TiO₂/Ag nanoparticles increased when the [water]/[DDBA] molar ratio rose. The resultant Ag nanoparticles over the anatase crystal TiO₂ nanoparticles exhibited a strong surface plasmon resonance (SPR) peak at about 430 nm. The SPR peak shifted to the red side with the increase in nanoparticle size. Conductive pastes with 70 wt% TiO₂/Ag nanoparticles were prepared, and the pastes were coated on the PET films using a screen-printing method. The printed paste films of the TiO₂/Ag nanoparticles demonstrated greater surface resistance than conventional Ag paste in the range of 405~630 μΩ/sq.

• Korean Journal of Dental Materials
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• v.44 no.3
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• pp.263-272
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• 2017

In this study, antibacterial chlorhexidine (CHX)-containing hydroxyapatite (HAp) was coated on titanium and investigated its characteristics. Ti-mSBF-CHX group was prepared by soaking titanium disks in the modified simulated body fluid (mSBF) mixed with CHX. Ti-mSBF group was coated using mSBF without CHX. Ti-mSBF-adCHX group was prepared by soaking Ti-mSBF specimen in CHX-containing solution. The crystallines clusters composed with nano-shaped crystallites were coated on the surface of the Ti-mSBF specimen. The ribbon-shaped crystallites were observed with the crystalline clusters on the Ti-mSBF-CHX specimen. The content of CHX chemical compositions was high in ribbon-shaped crystallites. HAp crystalline structure was dominant for all prepared specimens, and ${\beta}-TCP$ (tricalcium phosphate) and OCP (octacalcium phosphate) crystalline structures were observed in the Ti-mSBF-CHX specimen. FT-IR spectra showed the strong peaks of CHX in Ti-mSBF-adCHX and Ti-mSBF-CHX groups. However, after immersing in a phosphate buffered saline (PBS), CHX was rapidly released in Ti-mSBF-adCHX group, while it was slowly released in Ti-mSBF-CHX. We expect that the coating method of Ti-mSBF-CHX group could be used for protecting inflammation of titanium implant by incorporating antibacterial agent CHX into HAp layer.

• Membrane Journal
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• v.28 no.1
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• pp.1-20
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• 2018

Fresh water is an important resource for humans, and pressure-driven membrane technology has been widely known as an energy-efficient method to obtain water resource. However, membrane fouling phenomenon, which is one of the major issue during operation, deteriorates membrane permeability. These fouling is usually affected by interaction between surface of membrane and various foulants, therefore, modification of membrane's surface is one of the methods to improve fouling-resistance. This review focuses on the method to modify surface of pressure-driven membranes such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Specifically, there are two different surface modification methods: (1) adsorption and coating as the physical modification methods, (2) cross-linker, free radical polymerization (FRP), atom transfer radical polymerization (ATRP), plasma/UV-induced polymerization as the chemical modification methods. This review introduces the physico - chemical surface modification methods reported in recent papers and suggests research directions for membrane separation which can increase membrane fouling resistance.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.410-418
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• 2016

In this study, we prepared electrically conducting composites using epoxy resin of diglycidyl ether of bisphenol A (DGEBA) as a matrix, triethylenetetramine (TETA) as a hardener and nickel powder or multi-walled carbon nanotubes (MWCNTs) grafted with $-NH_2$ groups (MWCNT-$NH_2$) as electrically conducting fillers. Electrical conductivity of composite films were measured by coating on the slide glass with a doctor blade. We measured modification reactions of MWCNT and reaction of MWCNT-$NH_2$ with DGEBA epoxy resin by fourier transform infrared spectrometer (FTIR), thermogravimetric analyzer (TGA) and elemental analyzer (EA). Morphology of composites was investigated by scanning electron microscope (SEM) and sheet resistances of composites were measured by 4-point probe. We found $(9.87{\pm}1.09){\times}10^4{\Omega}/sq$ of sheet resistance for epoxy composite containing both 40 wt% nickel powder and 0.5 wt% of MWCNT-$NH_2$ as fillers, equivalent to epoxy composite containing 53.3 wt% nickel powder only as a filler.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.142-149
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• 2020

In this study, the electrochemical performance of Graphite/Silicon/Pitch composites as anode material was investigated to improve the low theoretical capacity of artificial graphite. Spherical artificial graphite surface was coated with polyvinylpyrrolidone (PVP) amphiphiles material to synthesize Graphite/Silica material by silica islands growth. The Graphite/Silicon/Pitch composites were prepared by petroleum pitch coating and magnesiothermic reduction. The Graphite/Silicon/Pitch composite electrodes manufactured using poly(vinylidene fluoride) (PVDF), carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) binders. The coin type half cell was assembled using various electrolytes and additives. The Graphite/Silicon/Pitch composites were analysed by X-ray diffraction (XRD), scanning electron microscope (SEM) and a thermogravimetric analyzer (TGA). The electrochemical characteristics of Graphite/Silicon/Pitch composite were investigated by constant current charge/discharge, rate performance, cyclic voltammetry and electrochemical impedance spectroscopy. The Graphite/Silicon/Pitch composites showed high cycle stability at a graphite/silica/pitch ratio (1:4:8 wt%). When the electrode is prepared using PAA binder, the high capacity and stability is obtained. The coin type half cell assembled using EC: DMC: EMC electrolyte showed high initial capacity (719 mAh/g) and excellent cycle stability. The rate performance has an capacity retention (77%) at 2 C/0.1 C and an capacity recovery (88%) at 0.1 C / 0.1 C when the vinylene carbonate (VC) was added.

• Membrane Journal
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• v.4 no.3
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• pp.152-162
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• 1994

The photodegradation efficiency of formic acid on $TiO_2$ photocatalytic membranes was investigated. A new titania membrane reactors for purification of water combining microfiltration with photocatalytic degradation of organic compounds were developed. Titania membrane tubes(average pore size of $0.2\mu m$) were prepared by the slip casting, and porous thin films of $TiO_2$ were formed on the tube surface by the sol-gel process to increase the surface area, and consequently to increase photodegradation efficiency of organic compounds. The UV light with the wavelength of 365 nm was used as a light source for photocatalytic reactions. The photodegradation efficiency of the organic compounds was strongly dependent on the flux of the solution, the microstructure of the membrane (sol pH), and the amount of $O_2$ supplied. The effects of the primary oxidant such as $H_2O_2$ and dopants such as $Nb_2O_5$ on the photodegradation efficiency were also investigated. The results showed that more than 80% of formic acid could be degraded using membrane coated with a $TiO_2$ sol of pH 1.45. The photodegradation efficiency could be improved by about 20% when adding $H_2O_2$ in feed solution or doping $TiO_2$ membranes with $Fe_2O_3$.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2002.08a
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• pp.13-31
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• 2002

쌀은 중국에서 중요한 식량작물로 제9차 5개년 계획(1966-2000년) 동안 재배면적 31.4백만 ha이며 생산량은 단위 ha당 6,303kg으로 198백만톤에 이르며 이는 재배면적으로는 식량작물의 27.7%, 그리고 생산량으로는 전체식량작물의 40%를 각각 점하고 있다. 이러한 재배면적과 생산량은 각각 세계전체면적과 생산량의 20.7%와 33.7%를 차지하는 많은 량이다. 중국의 남부지역은 전지역의 73.5%가 이모작으로 재배되며 주품종은 Indica이다. 중국의 중부지역은 이모작과 일모작의 재배형태가 2:3으로 공존하고 있으며 양쯔강 이북은 주로 일모작의 형태이다. 중국의 쌀 재배면적은 1960년대 이후 점차 증가하다가 1980년대 후반으로 정체되었다가 최근 90년대 말에 이르러서는 재배면적의 감소가 가속화되고 있으나 단보당 생산량은 꾸준히 증가하고 있다. 2001년 중국의 쌀소비량은 138백만톤으로 이의 85.2%는 식량용으로, 5.8%는 사료용으로, 1.3%는 가공용, 1.5-2.0%는 수출용으로 그리고 1.2%는 종자용으로 소비되었다. WTO체제에 들어서도 중국의 쌀 생산에는 크게 영향을 받지않을 것으로 여겨지는데 그 이유로는 충분한 생산능려과 자급률, 쌀의 낮은(4%) 국제교역비율, 총생산량에 대한 낮은 쿼터비율 등을 들 수 있다. 그러나 WTO체제 가입에 따른 압력 또한 존재하는 것이 사실인데 그것은 낮은 품질, 국제가격보다 높은 국내가격 등을 들 수 있다. 향후 중국 쌀의 발전적 전략들로는 쌀의 안정적 발전을 지속하는 일, 쌀 재배구조 조정과 함께 높은 미질을 가지는 품종육종, 기계화를 비롯한 경작기술의 발달, 쌀과 부산물 가공기술의 개발연구, 특징 기능을 함유하는 유전공학적 기술의 적용, 토지와 도시화 그리고 식량순환에 시스템의 개혁 등 과학기술을 고양하는 일 등을 들 수 있다.TEX>$\times$10cm의 소식일수록 짧아서 재식주수와 경장은 정의상관이 인정되었다. 9 경직경은 30$\times$10cm, 40$\times$10cm의 소식일수록 크고 20$\times$10cm의 밀식일수록 작았다 10. 수량구성요소인 주근장과 수량인 건근중은 30$\times$10cm, 40$\times$10cm의 재식주수가 적을수록 높아서 재식주수와는 부의 상관이 인정되었다. 11 이상과 같은 결과로 보아 경직경이 크고 주근장이 길어서 10a당 건근중이 많은 30$\times$10cm(33주/$m^2$)가 알맞은 재식거리였다.에 대한 인식을 새롭게 하고 농약취급시의 건강장해예방행동을 촉구하는 등의 효과도 높은 것으로 예방의학적인 유용성이 크다고 볼 수 있다. 미침을 알 수 있었다. 대두 단백질로 코팅된 golden delicious는 상온에서60일 동안 보관하였을 경우, 사과표피의 색도 변화를 현저히 지연시킴을 확인하였다. 또한 control과 비교하여 성공적으로 사과에 코팅하였으며, 상온에서 보관하여을 때 사과의 품질을 30일 이상 연장하는 효과를 관찰하였다. 이들 결과로부터 대두단백질 필름이 과일 등의 포장제로서 이용할 가능성을 확인하였다.로 [-wh] 겹의문사는 복수 의미를 지닐 수 없 다. 그러면 단수 의미는 어떻게 생성되는가\ulcorner 본 논문에서는 표면적 형태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다. 즉, [+wh] 의미의 겹의문사는 동일한 구성요 소를 지닌 병렬적 합성어([$

• Membrane Journal
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• v.19 no.1
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• pp.25-33
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• 2009

PES (polyethersulfone) membranes with highly enhanced their asymmetry were prepared by phase inversion process. The membranes were prepared by using PES/DMF (N,N-dimethylformamide)/TSA (p-toluenesulfonic acid)/PVP (polyvinylpyrrolidone) casting solution and water coagulant. The pre-coagulation of membrane surface which was induced by an addition of TSA as a demixing agent and PVP as a swelling polymer in the PES solution and humid exposure time, played a crucial role in determining morphological properties and the PWP (pure water permeation) performance. The PES solution was coated on polyester film under condition of 80% humidity for a while ($72{\sim}144$ sec) before immersing in a coagulation bath. The characterization of membranes was carried out by a capillary flow porometer, a FE-SEM and a permeation test apparatus. As the thickness of the smallest pore size layer (SPL) decreased, the asymmetry of membrane increased under conditions of 20 wt% of TSA and 10 wt% of PVP in 11 wt% of PES solution during longer humid contact time. As a result, the membranes showed a remarkable increase of PWP.

• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.134-140
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• 2017

In this study, we made UV cured acrylic pressure sensitive adhesive containing silicone-urethane-acrylate (SUA) oligomer for a coating on protective film and investigated the effect of SUA oligomer content and UV-dose on adhesion properties. The results illustrated that peel strength decreases with increasing oligomer content and UV-dose, while holding power increases. The gel fractions sharply increased after UV irradiation and then remain constant with prolonged UV exposure. From peel-off test, sample S70 (70% oligomer content) shows the best peelability and removability without remaining any mark or adhesive material on the test substrate than S50 (50% oligomer content) and S60 (60% oligomer content). Sample S70 also showed a surface energy lower than $26mJ/m^2$ and a transmittance higher than 95% at UV-dose 1857 and $2270mJ/cm^2$ which met the required properties for protective film application.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.51.2-51.2
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• 2009

본 실험에서는 레이저 간섭 리소그래피를 이용한 2차원 나노 패턴을 형성하였고, 수열합성법을 이용하여 90 도에서 ZnO 나노 기둥을 ZnO/Si 기판 상에 제작 하였다. ZnO 버퍼층은 스퍼터를 이용하여 200도, Ar 분위기에서 증착 하였으며, 레이저 간섭 리소그래피를 이용하여 두 번의 노광을 통해 2차원 나노 패턴을 형성하였다. 먼저, 최적화된 포토레지스트를 ZnO/Si 기판 위에 도포하고, 2500rpm에서 30초간 스핀코팅 한 후, 첫번째 노광을 실시 하였고, ZnO/Si 기판을 회전시켜 첫번째 노광과 교차 시킨 다음 두 번째 노광을 통해 교차하는 부분만 현상되도록 하였다. 기판의 회전 및 기판과 입사 레이저 사이의 각도를 조절하여 제작된 나노 패턴의 종류는 square lattice, centered rectangular lattice, oblique lattice, hexagonal lattice, rectangular lattice, 5가지로, 2차원의 모든 격자를 제작 하였다. 저온 수열합성법에서는 Na citrate를 형상제어제 (surfactant ions)로 사용하여 ZnO 나노 기둥을 형성하였다. $NH_4OH$를 이용하여 용액의 pH를 조절하였고, Zn nitrate hexahydrate를 Zn의 원료 물질로 사용하였다. 2차원 나노 패턴의 3차원 형태는 Atomic force microscopy (AFM, Veeco instruments, USA)를 이용하여 접촉 모드에서 관찰하였고, ZnO 나노 구조는 주사 전자 현미경 (FE-SEM, Model: JSM-6701F, Tokyo, Japan) 를 통하여 분석 하였다. 나노 패턴의 AFM 분석 결과 ZnO/Si 기판상에 포토레지스트가 주기적인 배열을 가지는 것을 확인하였고, ZnO/Si 기판상에 포토레지스트가 완전히 현상된 부분이 일정한 배열을 가지는 것을 확인하였다. 포토레지스트가 현상되어 기판의 표면이 드러난 부분의 크기는 약 250nm로 측정되었다. ZnO 나노 구조의 FE-SEM 분석 결과, 각각의 나노 구조가 나노패턴 중 완전히 현상된 부분만을 통하여 성장되었다는 것을 확인하였고, 형상 제어제로 사용된 Na citrate의 첨가 여부에 따라 나노 구조의 모양이 변화되었다는 것을 알 수 있었다. Na citrate 가 첨가된 나노 기둥의 경우 약 500nm의 길이를 가지는 하나의 기둥 형태로 성장하였다는 것을 확인하였다.