• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.221-221
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• 2013

Striving to replace the well known silicon nanocrystals embedded in oxides with solution-processable charge-trapping materials has been debated because of large scale and cost effective demands. Herein, a silicon quantum dot-polystyrene nanocomposite (SiQD-PS NC) was synthesized by postfunctionalization of hydrogen-terminated silicon quantum dots (H-SiQDs) with styrene using a thermally induced surface-initiated polymerization approach. The NC contains two miscible components: PS and SiQD@PS, which respectively are polystyrene and polystyrene chains-capped SiQDs. Spin-coated films of the nanocomposite on various substrate were thermally annealed at different temperatures and subsequently used to construct metal-insulator-semiconductor (MIS) devices and thin film field effect transistors (TFTs) having a structure p-$S^{++}$/$SiO_2$/NC/pentacene/Au source-drain. C-V curves obtained from the MIS devices exhibit a well-defined counterclockwise hysteresis with negative fat band shifts, which was stable over a wide range of curing temperature ($50{\sim}250^{\circ}C$. The positive charge trapping capability of the NC originates from the spherical potential well structure of the SiQD@PS component while the strong chemical bonding between SiQDs and polystyrene chains accounts for the thermal stability of the charge trapping property. The transfer curve of the transistor was controllably shifted to the negative direction by chaining applied gate voltage. Thereby, this newly synthesized and solution processable SiQD-PS nanocomposite is applicable as charge trapping materials for TFT based memory devices.

• 한국의류학회지
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• 제41권1호
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• pp.131-140
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• 2017

Uniform nanofibers of polyurethane with different content of Juniperus Chinensis extracts (JCE) were successfully prepared by the electrospinning method. We investigated physiochemical properties of prepared compound nanoweb according to various concentrations of Juniperus Chinensis extracts using a Fourier transform infrared (FT-IR) spectrometer, X-ray diffractometer (XRD), thermogravimeter (TGA), and differential scanning calorimeter (DSC). The antibacterial activity of the JCE loaded PU nanofiber was conducted using the disk diffusion test against Gram-positive and Gram-negative bacteria. JCE was induced in the infrared spectra in the absorption band of PU/JCE nanowebs at $3,300cm^{-1}$, $2,960cm^{-1}$, $1,400-1,600cm^{-1}$, and $1,050cm^{-1}$. Thermal stability decreased with increasing JCE content in the PU/JCE nanowebs. The DSC curve of the PU nanoweb shows an endotherm peak at $420^{\circ}C$; in addition, the peak also became smaller and broader with increasing JCE content. The diffraction intensities of PU observed at 2 theta of $20^{\circ}$ decreased with the increasing amount of JCE in the compound nanoweb. In addition, the crystal intensities of the compound nanowebs also decreased along with the JCE content. Structural analysis indicates that JCE and PU are miscible. Juniperus Chinensis incorporated PU nanofibers demonstrated excellent antibacterial properties against both Gram-positive and Gram-negative bacteria.

• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.713-717
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• 2009

The dependence of the catalytic properties of horseradish peroxidase on the structural changes of ionic liquids was investigated with two water-miscible ionic liquids, N-butyl-3methypyridinium tetraftuoroborate ([$BMP_y$][$BF_4$]) and 1-butyl-3-methylimidazolium methylsulfate ([BMIM][$MeSO_4$]), each of which shares an anion ($BF_4^-$) or a cation ($BMIM^+$) with 1-butyl-3-methylimidazolium tetraftuoroborate ([BMIM][$BF_4$]), respectively. The oxidation of guaiacol (2-methoxyphenol) with $H_2O_2$was used as a model reaction. In order to minimize the effect of solution viscosity on the kinetic constants of the enzymatic catalysis, the enzymatic reactions for the kinetic study were performed in water-ionic liquid mixtures containing 25% (v/v) ionic liquid at maximum. Similarly to the previously reported results for [BMIM][$BF_4$], as the concentration of [$BMP_y$][$BF_4$] increased, the $K_m$value increased with a decrease in the $k_{cat}$value: the $K_m$value increased markedly from 2.8 mM in 100% water to 12.6 mM in 25% (v/v) ionic liquid, indicating that ionic liquid significantly weakens the binding affinity of guaiacol to the enzyme. On the contrary, [BMIM][$MeSO_4$] decreased the Km value to 1.4 mM in 25% (v/v) ionic liquid. [BMIM][$MeSO_4$] also decreased $k_{cat}$more than 3-folds [from 13.8 $s^{-1}$in 100% water to 4.1 $s^{-1}$in 25% (v/v) ionic liquid]. These results indicate that the ionic liquids interact with the enzyme at the molecular level as well as at a macroscopic thermodynamic scale. Specifically, the anionic component of the ionic liquids influenced the catalysis of horseradish peroxidase in different ways.

• 한국토양비료학회지
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• 제44권1호
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• pp.15-21
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• 2011

Transport of heavy metals such as Cd is affected by several rate-limiting processes including adsorption and desorption by exchange reactions in soils. In this study, column transport and batch kinetic experiments were performed to assess Cd mobility in a double-layered soil with a reclaimed saline and sodic soil (SSS) as top soil and macroporous granule (MPG) as a bottom layer. For individual soil layer having different physical and chemical properties, Cd was considered to be nonlinear reactivity with the soil matrix in layered soils. The dispersive equation for reactive solutes was solved with three types of boundary conditions for the interface between soil layers. The adsorption of Cd with respect to the saline-sodic sandy loam and the MPG indicated that the nature of the sites or the mechanisms involved in the sorption process of Cd was different and the amounts of Cd for both of samples increases with increasing amounts of equilibrium concentration whereas the amount of Cd adsorbed in saline-sodic sandy loam soil was higher than that in MPG. The results of breakthrough curve indicating relative Cd retardation accompanied by layer material and sequence during leaching showed that the number of pore volumes to reach the maximum relative concentration of 1 increased in the order of MPG, SSS, and double layer of SSS-MPG. Breakthrough curves (BTCs) from column experiments were well predicted with our double-layered model where independently derived solute physical and retention parameters were implemented.

• 대한화장품학회지
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• 제25권4호
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• pp.97-110
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• 1999

The new stick make-up product was studied by using a gel, which is a viscous complex formed with clay minerals, vitamins A and E and fluorinated liquid polymer with a 1500 molecular weight. The gel cannot be obtained with any random combination of clay minerals and the ingredients described above. It takes the sequential manufacturing method as follows to get this kind of gel. Firstly, clay minerals and liquid polymers have to be pre-mixed in order to saturate the liquid polymers with the clay minerals. Then the on-processed gel has to be finely crystallized. The clay minerals, which are the core elements for this gel, were used as a function of Binder & Buffer and liquid polymer was mixed together for the deterioration of the surface tension of each component and to form a functional film in the gel. This liquid polymer was combined with clay minerals because it is not miscible with most oils and solvents. Waxes have a function of keeping a solid status in the stick. We reduced the usage of waxes by putting clay minerals as buffer in the proportion of 0.5:1 with oil phase. Ceramide takes care of the skin when used regularly and maintains the skin's moisture. Vitamins A and E contribute to preventing skin aging by the activation of skin cells. We could get the stable viscous gel, which has about 80% oil phase using clay minerals and liquid polymer. The crystalline structures of gel were surface-chemically-analyzed using SEM and Image Analyzer and were thermodynamically analyzed using DSC. Surface tension test and softness were done by Rheometer. In the end, these characteristics were verified by consumer panel tests in Seoul, Daegeon and Pusan in Korea and Hokkaido, Osaka and Miyazaki in Japan with correlation to the climate.

• 설비공학논문집
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• 제6권4호
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• pp.439-452
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• 1994

One of the chlorofluorocarbon compounds. R-12 deplete atmospheric ozone. It leads to international agreement to reduce CFC production. R-134a has similar thermodynamic properties to CFC-12. It has zero ODP(Ozone Depletion Potential). This Paper focuses on the lubricating oils for using with R-134a PAGs(Polyalkylene Glycol's) and esters are primary lubricants that are now being tested for use with R-134a Because of extreme polarity of R-134a. there are many problems in the selection of lubricating oil. This investigation analyzes compressor working conditions and calculates wear parts friction for simulation testing. Miscibility and material compatibility is proved by sealed glass tests. Friction was tested on the closed type pin on disk wear tester. This equipment simulates actual refrigerating compressor. Environment controlled test made more reliable result than field test Conventional oils(mineral oils, Alkylbenzene, PAO(Polyalpha Olefin) are immiscible with R-134a. PAGs and ester oils are miscible with R-134a. Friction coefficient is similar to conventional system(mineral oil/R-12 systems) at operating condition. At start & stop condition, PAGs/R-134a system has high friction coefficient. It provide reliable result on the lubricity, miscibility, material compatibility of R-134a with these new lubricants. It suggests proper selection of refrigeration oil that may improve compressor durability of performance.

• 폴리머
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• 제24권1호
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• pp.48-57
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• 2000

Polycaprolactone (PCL)과 열가소성 전분(thermoplastic starch (TPS))을 이용하여 여러 조성의 블렌드를 제조하였다. PCL/TPS 조성을 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90으로 조절한 블렌드의 기계적 물성, 열적 특성, 흡습성, 퇴비화법에 의한 생분해도, 표면 형상 등을 측정, 분석하였다. 인장강도와 신장률은 TPS 함량이 증가함에 따라 감소하였으나, 탄성률은 TPS의 함량이 30%까지 증가하였다. TPS는 23$^{\circ}C$와 126$^{\circ}C$에서 2개의 유리전이온도(T$_{g}$ )를 의였으며, 결정의 용융점 (T$_{m}$ )을 나타내는 흡열 곡선은 보이지 않는 것으로 보아 열가소성 전분은 무정형 고분자임을 알 수 있었다. PCL/TPS 블렌드의 T$_{g}$ 와 T$_{m}$ 변화는 PCL과 TPS 사이의 상용성은 없는 것으로 나타났지만, 블렌드 필름의 파단면 형상을 보여주는 전자현미경 사진은 PCL과 TPS는 서로 상분리가 일어나지만 기계적 상용성은 있는 것으로 나타났다. 45일간의 생분해 실험에서 PCL의 생분해도는 44%였고 PCL/TPS 블렌드의 생분해도는 TPS의 함량이 증가함에 따라 생분해도가 증가하였다.

• 한국유가공학회:학술대회논문집
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• 한국유가공기술과학회 2001년도 제52회 춘계유가공심포지움 - 최근 유제품 기술개발 동향 및 경쟁력 제고
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• pp.15-23
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• 2001

우유는 유화나 colloid상태 때문에 우유의 다양한 정량을 위해서는 투명화 이용이 대단히 유용하다. 지방구 butanone에 의하여 분산될 수 있고 casein 복합체는 우유내에서 동시에 SDS 와 NaOH의 작용의 도움으로 Triton 작용에 의하여 단량체로 분해될수 있는데 왜냐하면 butanone은 양친매성이고 물에 섞일수 있는 용매이기 때문이다 용매 배합비율 T:B/8:2 와 T:B/9:1을 제외하고 모든 비율들이 각종 유제품을 투명화시킬수 있다. 용매가 세포와 접촉생장이 억제됨에도 불구하고 이배합은 균수 측정에 사용될수있는데 왜냐하면 세포벽을 공격하지 않기 때문이다. 이러한 이유 때문에 이기술은 원유품질관리, 유대지불, 제품관리, 국가적 낙농 계획 조절에 유용하다.

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.399-405
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• 2001

Urushiol, a natural pro-electrophilic quinone compound, has potential structural characteristics as antitumor chemotherapeutic agents. However, urushiol's use as an antitumor drug has some problems, because it is hardly miscible with an aqueous solution. Purified urushiol is highly viscous and soluble only in strong solvents. for this study, we prepared an urushiol-ethanol micro-emulsion with a unimodal size distribution by high-speed homogenization. This generated effective delivery of urushiol to its action wites, so that we could investigate its cytotoxic activity against cancer cells. Using a colony-forming assay, we were able to show that urushiol selectively inhibited the growth of the ovarian cancer cells PA-1 and 2774 at a concentration of $10^{-6}$, whereas it had only a negligible effect on normal CHO cells at the same concentration. The data suggest that urushiol may have potential as an effective antitumor agent in the treatment of ovarian cancer. In addition, we addressed the question of whether the specific cytotoxic effect of urushiol is linked to apoptosis, by DNA fragmentation and DAPI staining assays. The inhibitory effects of urushiol on the growth of ovarian cancer cells was found to be associated with DNA fragmentation and the fragmented nuclei formation, both of which represent markers for the induction of apoptosis. Therefore, the results suggested that urushiol affected its profound cytotoxicity by triggering apoptosis in ovarian cancer cells.

• 접착 및 계면
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• 제2권1호
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• pp.18-22
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• 2001

Poly(vinylidene fluoride)(PVDF)를 포함하는 고분자 블렌드 필름의 표면층의 모폴로지를 원자력간 현미경과 시차주사열량계 측정을 토대로 연구하였다. ${\alpha}$ 및 ${\gamma}$형 결정상을 가진 PVDF는 Poly(methyl methacrylate)(PMMA) 및 가수분해된 PMMA(carboxyl content:14wt%)와의 블렌딩에서 표면층은 PVDF의 결정상만으로 이루어져 있음을 확인하였다. 그러나 PMMA의 결정상이 가수분해율이 증가함에 따라 표면 자유에너지의 차이도 증가함에도 불구하고 가수분해된 PMMA의 존재를 확인하였다. 이러한 결과는 표면층에서의 낮은 표면 자유에너지 성분인 PVDF의 농축 정도는 자유에너지 차보다 상호작용력의 크기에 밀접히 관련되어 있음을 알 수 있었다. 한편, carboxyl group의 도입은 PVDF와 PMMA의 상용성을 저해하는 것으로 밝혀졌다.