• 문화기술의 융합
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• 제4권2호
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• pp.211-216
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• 2018

흡착과 막을 융합시킨 분리기술은 수처리와 같은 환경 분야에서 많은 응용이 기대된다. 이 융합기술에 막분리 공정에서 문제가 되는 막 fouling을 억제시키기 위해 막표면에 카본휘스커를 성장시킨 기능성 카본막을 개발하였다. 본 연구에서는 기능성 카본막의 제조 Mechanism을 밝히기 위해, 각각의 혼합비율인 폴리머라텍스로 전처리를 하고 CVD(Chemical Vapor Deposing)법에 따라 막을 제조하였다. 이 막을 주사전자현미경(Scanning Electron Microscope(SEM)), CHN분석기(Elemental Analyzer), X-선회절법(X-Ray Diffraction(XRD))으로 분석하였다. 그 결과 3번막(PVdC(PolyVinyl di-Chloride):PVC(Polyvinly Chloride)=4.5:55)의 경우가 카본휘스커의 직경과 밀도가 높았다. 이것은 폴리머라텍스의 수소함유량에 따라 카본휘스커의 직경과 밀도를 조절하는 것이 가능할 것으로 보인다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.181-181
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• 2016

Hydrogenated microcrystalline silicon (${\mu}c-Si:H$) films have attracted much attention as materials of the bottom-cells in Si thin film tandem photovoltaics due to their low bandgap and excellent stability against light soaking. However, in PECVD, the source gas $SiH_4$ must be highly diluted by $H_2$, which eventually results in low deposition rate. Moreover, it is known that high-rate ${\mu}c-Si:H$ growth is usually accompanied by a large number of dangling-bond (DB) defects in the resulting films, which act as recombination centers for photoexcited carriers, leading to a deterioration in the device performance. During film deposition, Si nanoparticles generated in $SiH_4$ discharges can be incorporated into films, and such incorporation may have effects on film properties depending on the size, structure, and volume fraction of nanoparticles incorporated into films. Here we report experimental results on the effects of nonoparticles incorporation at the different substrate temperature studied using a multi-hollow discharge plasma CVD method in which such incorporation can be significantly suppressed in upstream region by setting the gas flow velocity high enough to drive nanoparticles toward the downstream region. All experiments were performed with the multi-hollow discharge plasma CVD reactor at RT, 100, and $250^{\circ}C$, respectively. The gas flow rate ratio of $SiH_4$ to $H_2$ was 0.997. The total gas pressure P was kept at 2 Torr. The discharge frequency and power were 60 MHz, 180 W, respectively. Crystallinity Xc of resulting films was evaluated using Raman spectra. The defect densities of the films were measured with electron spin resonance (ESR). The defect density of fims deposited in the downstream region (with nonoparticles) is higher defect density than that in the upstream region (without nanoparticles) at low substrate temperature of RT and $100^{\circ}C$. This result indicates that nanoparticle incorporation can change considerably their film properties depending on the substrate temperature.

• 한국식품영양과학회지
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• 제28권5호
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• pp.1164-1171
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• 1999

In this study, we investigated the effects of obesity index on the risk factors of chronic diseases in obese children. The subjects were male and female children aged 9 to 12. The average obesity index was 147.7$\pm$13.8% in boys and 147.6$\pm$16.5% in girls. The average percentages of body fat was significantly higher in boys(33.9$\pm$5.7%) than in girls(30.7$\pm$4.4%). It was found that 26% of subjects had abnormal serum GOT and GPT values. Percentages of subjects at risk of cardiovascular disease(CVD) based on corresponding criteria of TG, T chol, HDL chol, and LDL chol were 28.6%, 28.6%, 45.5% and 42.7%, respectively. The risk of CVD was increased with the degree of obesity, which was not significant. The AI(atherogenic index) was higher in boys(4.6$\pm$2.3) than in girls(3.6$\pm$1.2). The serum T chol and LDL chol levels of subjects whose mother are in thirties were significantly higher than those of subjects whose mother are in fourties. The T chol levels of subjects who had mother with job were significantly higher compaired to those of subjects who had housewife mother. The results indicated the urgent need of nu tritional management for the obese children to prevent further devel opment of childhood obesity and hyperlipidemia. Based upon this study, devising method and media for the mother nutritional education as well as for the children nutritional education is required for better growth and health promotion of primary school children.

• 한국전기전자재료학회논문지
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• 제23권5호
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• pp.397-402
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• 2010

In this paper, we studied WVTR(water vapor transmission rate) properties of $Si_3N_4$ thin film that was deposited using TCP-CVD (transformer coupled plasma chemical vapor deposition) method for the possibility of OLED(organic light emitting diode) encapsulation. Considering the conventional OLED processing temperature limit of below $80^{\circ}C$, the $Si_3N_4$ thin films were deposited at room temperature. The $Si_3N_4$ thin films were prepared with the process conditions: $SiH_4$ and $N_2$, as reactive gases; working pressure below 15 mTorr; RF power for TCP below 500 W. Through MOCON test for WVTR, we analyzed water vapor permeation per day. We obtained that WVTR property below 6~0.05 gm/$m^2$/day at process conditions. The best preparation condition for $Si_3N_4$ thin film to get the best WVTR property of 0.05 gm/$m^2$/day were $SiH_4:N_2$ gas flow rate of 10:200 sccm, working pressure of 10 mTorr, working distance of 70 mm, TCP power of 500 W and film thickness of 200 nm. respectively. The proposed results indicates that the $Si_3N_4$ thin film could replace metal or glass as encapsulation for flexible OLED.

• Nutrition Research and Practice
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• 제8권4호
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• pp.445-452
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• 2014

BACKGROUND/OBJECTIVES: High sensitivity C-reactive protein (hsCRP) is a strong independent predictor of future cardiovascular disease (CVD) risk. We evaluated the relationship between hsCRP and dietary intake in apparently healthy young women living in southern Vietnam. SUBJECTS/METHODS: Serum hsCRP was measured and dietary intake data were obtained using the 1-day 24-hour recall method in women (n = 956; mean age, $25.0{\pm}5.7$ years) who participated in the International Collaboration Study for the Construction of Asian Cohort of the Korean Genome and Epidemiology Study (KoGES) in 2011. RESULTS: Women in the high risk group (> 3 mg/L) consumed fewer fruits and vegetables, total plant food, potassium, and folate than those in the low risk group (< 1 mg/L). A multiple regression analysis after adjusting for covariates revealed a significant negative association between hsCRP and fruit and vegetable consumption. A logistic regression analysis showed that the odds ratio (OR) of having a high hsCRP level in women with the highest quartiles of consumption of fruits and vegetables [OR, 0.391; 95% confidence interval (CI), 0.190-0.807], potassium [OR, 0.425; 95% CI, 0.192-0.939] and folate [OR, 0.490; 95% CI, 0.249-0.964] were significantly lower than those in the lowest quartiles. CONCLUSIONS: These results suggest that, in young Vietnamese women, an increased consumption of fruit and vegetables might be beneficial for serum hsCRP, a risk factor for future CVD events.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.165-165
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• 2014

In this study, we demonstrated that the soft lithographic patterning processing of chemical vapor deposition (CVD) graphene and rGO sheets as large scale, low cost, high quality and simplicity for future industrial applications. Recently, a previous study has reported that single layer graphene grown via CVD was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp [1]. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide (DMSO) molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface [2]. Further, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or simple and efficient chemical sensor consisting of reduced graphene oxide (rGO) and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.552-552
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• 2013

In our study we consider Al2O3 ceramic substrates for Plasma Surface Treatments in order to improve deposited diamond surface and increase diamond deposition rate by applying DBD (Dielectric Barrier Dischrge) system. Because Plasma Surface Treatments was used as a modification method of material surface properties like surface free energy, wettability, and adhesion. By applying Plasma Surface Treatments diamond films are deposited on the Al2O3 ceramic substrates. DC Arc Plasmatron with mathane and hydrogen gases is used. Deposited diamond films are investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) is studied. As a result, nanocrystalline diamond films were identified by using SEM and diamond properties in XRD peaks at (111, $43.8{\Box}$, (220, $75.3{\Box}$ and (311, $90.4{\Box}$ were shown. Absorption peaks in FTIR spectrum, caused by CHx sp3 bond stretching of CVD diamond films, were identified as well. Finally, we improved such parameters as depostion rate ($2.3{\mu}m$/h), diamond surface uniformity, and impurities level by applying Plasma Surface Treatments. These experimental results show the importance of Plasma Surface Treatments for diamond deposition by a plasma source.

• 한국세라믹학회지
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• 제50권6호
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• pp.359-363
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• 2013

Silicon carbide and its composites are being considered as a nuclear fuel cladding material for LWR nuclear reactors because they have a low neutron absorption cross section, low hydrogen production under accident conditions, and high strength at high temperatures. The SiC composite cladding tube considered in this study consists of three layers, monolith CVD SiC - $SiC_f$/SiC composite -monolith CVD SiC. The volume fraction of SiC fiber and surface roughness of the composite layer affect mechanical and corrosion properties of the cladding tube. In this study, various types of SiC fiber preforms with tubular shapes were fabricated by a filament winding method using two types of Tyranno SA3 grade SiC fibers with 800 filaments/yarn and 1600 filaments/yarn. After chemical vapor infiltration of the SiC matrix, the surface roughness and fiber volume fraction were measured. As filament counts were changed from 800 to 1600, the surface roughness increased but the fiber volume fraction decreased. The $SiC_f$/SiC composite with a bamboo-like winding pattern has a smaller surface roughness and a higher fiber volume fraction than that with a zigzag winding pattern.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2390-2395
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• 2009

공간속도 $30000\;hr^{-1}$에서 Fe/ZSM-5 촉매의 $SiO_2/Al_2O_3$ 몰비가 감소함에 따라 $NO_x$ 제거 수율은 증가하였다. Fe/ZSM-5는 반응 온도 $350^{\circ}C$ - $400^{\circ}C$ 사이에서 최대 50%의 질소 산화물 제거 수율을 나타내지만 높은 CO 발생량이 관찰된다. Fe/ZSM-5 촉매에서 생성되는 CO를 제거하기 위하여 Co-Pt/ZSM-5 촉매를 직렬로 연속하여 사용하였으며, 공간속도 $30000\;hr^{-1}$, 반응 온도 $250^{\circ}C$ 조건에서 90% 이상의 질소 산화물과 CO 제거 수율을 나타내었다.