• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.51-51
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• 2008

Carbon nanotubes (CNTs) have long been reported as an ideal material due to their excellent electrical conductivity and chemical and mechanical stability as well as their high aspect ratios for field emission devices. CNT emitters made by screen printing the organic binder-based CNT paste may act as a source to release gases inside a vacuum panel. These residual gases may cause a catastrophic damage by electrical arcing or ion bombardment to the vacuum microelectronic devices and may change their physical or electrical properties by adsorbing on the CNT emitter surface. In this study, we analyzed the composition of residual gases inside the vacuum-sealed panel by residual gas analyzer (RGA), investigating the effects of individual gases of different kinds at several pressures on the field emission characteristics of CNT emitters. The residual gases included $H_2$, CO, $CO_2$, $N_2$, $CH_4$, $H_2O$, $C_2H_6$, and Ar. Effect of residual gases on the field emission was studied by observing the variation of the pulse voltages with the duty ratio of3.3% to keep the constant emission current of $28{\mu}A$. Each gas species was introduced to a vacuum chamber up to three different pressures ($5\times10^{-7}$, $5\times10^{-6}$, and $5\times10^{-5}$ torr) each for 1 h while electron emission was continued. The three different pressure regions were separated by keeping a high vacuum of $\sim10^{-8}$ torr for a 1 h. The emission was terminated 6 h after the third gas exposure was completed. Field emission characteristics under residual gases will be discussed in terms of their adsorption and desorption on the surface of CNTs and the resultant change of work function.

• Korean Journal of Medicinal Crop Science
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• v.18 no.2
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• pp.118-125
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• 2010

This study was carried out to determine changes in general chemical composition, free sugars, physicochemical properties of extract, and ginsenoside contents depending upon processing methods. Ginseng roots harvested from the same field were employed for the processing into white ginseng (WG), taegeuk ginseng (TG), red ginseng A (RGA, steamed one time), and red ginseng B (RGB, steamed three times). The fat content decreased by increasing duration of treatment and number of steaming treatment. On the other hand, there was no significant variation in contents of ash and carbohydrate depending on processing methods. Contents of sucrose and maltose was higher in Taegeuk and red ginseng than those of white ginseng. Steamed ginseng root (taegeuk and red ginseng root) showed higher amount of water extractable solid than the unsteamed white ginseng, but the variation of crude saponin content was not distinctive depending on processing methods. The contents of total ginsenosides increased by the order of white, taegeuk, red A, and red B root. In summary, chemical composition and total ginsenoside content were different according to part of root and processing methods, thus implies the importance of quality control as well as pharmacological activity of ginseng root.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.154-154
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• 1999

금속산화막은 전자부품 및 광학적 응용에 널리 사용되고 있다. 특히 알루미늄의 산화막은 유전체의 재료로 커패시터에 많이 사용되고 있다. 이러한 알루미늄 산화막을 plasma를 이용한 ion plating에 의해 형성하였다.Activated Reactive Evaporation은 화합물의 증착율을 높이는데 좋은 증착법이다. 이러한 증착법에는 reactive ion plating와 ion-assisted deposition 그리고 ion beam sputtering 등이 있다. 본 연구에서는 알루미늄 산화막을 증착시키기 위해 plasma를 이용한 electron-beam법을 사용하였다. Turbo molecular pump로 챔버 내의 진공을 약 10-7torr까지 낸린 후 5$\times$10-5torr까지 O2와 Ar을 주입시켰다. 각 기체의 분압은 RGA(residual gas analyzer)로 조사하여 일정하게 유지시켰다. plasma를 발생시키기 위해 filament에서 열전자를 방출시키고 1kV 정도의 electrode에 의해 가속시켜 이들 기체들과 반응시켜 plasma를 발생시켰다. 금속 알루미늄을 5kV정도의 고전압과 90mA의 전류로 electron beam에 의해 증발시켰다. 기판의 흡착율을 높ㅇ기 위해 기판에 500V로 bias 전압을 걸어 주었다. 증발된 금속 알루미늄 증기들이 plasmaso의 산소 이온들과 활성 반응을 이루어 알루미늄 기판 위에 Al2O3막을 형성하였다. 알루미늄 산화막을 분석하기 위해 XPS(X-ray Photoelectron Spectroscopy)로 화학적 조성을 조사하였는데, 알루미늄의 2p전자의 binding energy가 76.5eV로 측정되었다. 이는 대부분 증착된 알루미늄이 산소 이온과 반응하여 Al2O3로 형성된 것이다. SEM(Scanning electron Microscopy)과 AFM(Atomim Force microscopy)으로 증착박 표면의 topology와 roughness를 관찰하였다. grain의 크기는 10nm에서 150nm이었고 증착막의 roughness는 4.2nm이었다. 그리고 이 산화막에 전극을 형성하여 유전 상수와 손실률 등을 측정하였다. 이와 같이 plasma를 이용한 3-beam에 의한 증착은 금속의 산화막을 얻는데 유용한 기술로 광학 재료 및 유전 재료의 개발 및 연구에 많이 사용될 것으로 기대된다.

• Resources Recycling
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• v.4 no.3
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• pp.2-9
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• 1995

The rccoverg and separation pracess of nikcl, vanadium and molybdenum from spent dcsulfilrizing catalyst ofpetrochemical rndustries was studied. Tnis process was canied out wet process which is consist of roasting, ammonialeaching and solve111 exDaction techniqcs. The metal ions of NI, V and Mo as vduable compollents were treated byroasting them a1 low lernperatuc, 400$^{\circ}$C in first dep, and then dlssah'ed nu1 at 80$^{\circ}$C wlth ammonium cabonate mlulion.Aftcr cooling them a1 room tempertaure, vanadium wa rccavered from mathcr iiquur in thc f n m of precipitate, sodiumvanadales The Secand slep, roasting the catalyst which is added sodium carbonate ul IOOO"C, was employed. Leachingwith distilled ~ a l e rga ve a iwo phase resultant, solutio~c~a ntaning Ni, V and Mo and solid residue containing sibca,alurmniu~n and iron. A solvcnt exlclction technique uslng vvriuus extractanls, MSP-8, TOIUC, LIX64Pi was eflecnve farthc extraclion and scparation ol thrcc mcfals from thc ammonical 11qou1 thc ammonical 11qou1.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.201-206
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• 2003

A residual gas analyzer was used to study the outgassing behavior of stainless steel 304 chamber as a function of bake-out temperature up to $235 ^{\circ}C$ and to identify the gas species evolved during turn on and degassing of the three different types of hot cathode ionization gauges. It was found that $H_2O$, CO, and $H_2O$ were the dominent outgassing species in the vacuum chamber during bake-out but finally $H_2$ and CO(mass 28) persisted at room temperature. Dominant outgassing species were also $H_2$ and $H_2O$ while fuming on the ionizations and then $H_2$,$H_2O$ and CO were found to be the main species degassed gauges. It was appeared that the outgassing species and quantity were not agreed to the three different types of hot cathode ionization gauges.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.295-295
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• 2010

KSTAR(Korea Superconducting Tokamak Advanced Research) 토카막에 설치되어 있는 ICRF(Ion Cyclotron Range Frequency) 시스템을 이용한 방전세정을 2008년에 이어 2009 KSTAR 플라즈마 campaign 동안에도 시행하였다. ICRF 시스템을 이용한 방전세정인 ICWC(Ion Cyclotron Wall Cleaning)는 ITER와 DEMO 같은 초전도 자석을 이용하는 토카막에서 토카막 shot 중간에 자장을 낮추지 않고 바로 방전 세정을 할 수 있는 방법이다. 토카막에서 방전세정은 탄소나 산소 화합물과 같은 불순물을 제거하여 방사에 의한 플라즈마 냉각을 막고 토카막 초기 start-up시 진공 챔버 벽면으로부터 의도하지 않은 연료주입을 제거하는 역할을 한다. 본 연구에서는 ICWC 방전 세정 플라즈마의 밀도특성과 균일도를 간섭계와 $H_{\alpha}$ line 세기를 통해 관측하고 RGA를 통해서 C, $H_2O$, $O^2$ 불순물의 제거량을 파악하는 한편 토카막의 신뢰성 있는 start-up을 위해 요구되는 벽면에서 토카막 방전가스의 제거량을 HD양을 통해서 조사하였다. 플라즈마 선적분 밀도는 약 $1{\sim}3{\times}10^{17}#/m^2$로 측정되었는데 이는 보통 He을 이용한 방전세정 플라즈마의 밀도에 해당한다. 한편 $H_{\alpha}$ line의 세기를 통해 ICWC 방전 플라즈마의 균일도를 살펴본 결과 안테나 전류띠의 중간이 아닌 끝부분에서 $H_{\alpha}$의 세기가 큰 것으로 나타났는데 이는 ICWC 플라즈마가 Inductive 방전보다는 capacitive 방전에 의해 생성되는 것으로 추정된다. ICWC 방전에서 C, $H_2O$, $O_2$ 불순물의 제거율은 각각 약 $4.2{\times}10^{-5}\;mbar{\cdot}l/sec$, $1.4{\times}10^{-3}\;mbar{\cdot}l/sec$ 그리고 $1.72{\times}10^{-4}\;mbar{\cdot}l/sec$로 각각 나타났는데 ICWC shot이 진행될수록 이 양은 점점 줄어들었다. 대표적인 He/$H_2$, He ICWC 방전 shot인 2118, 2123 shot에서 벽면에서 $D_2$의 제거율은 각각 약 $0.12\;mbar{\cdot}l/sec$와 $3.9{\times}10^{-3}\;mbar{\cdot}l/sec$로 나타났다. 이는 수소의 첨가로 인해 HD의 형태로 $D_2$의 제거율이 증가되었기 때문이다. 한편 $H_2$의 첨가는 챔버 벽면에 흡착되는 $H_2$ 양을 또한 증가시키므로 차후에 $H_2$ 만을 제거하는 He ICWC를 수행해야 할 것이다.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.463-470
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• 2012

As the advanced seeding technology through use of plug tray for good cultivation of seeds was propagated along with the expansion and development of horticultural industry, the use of bed soils as growing medium has recently been increased. In this study, the effects of the four clay minerals such as illite, phyllite, zeolite, and bentonite on the early growth of red pepper in the bed soil were investigated. Furthermore, proteome analysis for the leaf and stem samples of red pepper treated with only illite was performed. Of the seedling cultured, the healthy and regular size seeds were selected and cultivated in the pots, after they were treated with four clay minerals. The experiment was performed during the whole six weeks in the glasshouse of the Chungbuk National University. The growth lengths, fresh and dry weights of red pepper were significantly higher in the treatments of illite, phyllite, zeolite, and bentonite than in the control. In addition, the uptake of $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were higher in the treatment of illite, phyllite, zeolite, and bentonite than in the control. The 2-DE patterns for the red pepper by the applications of illite, phyllite, zeolite, and bentonite were similar to each other. Therefore, compared to the samples of control, the proteome analysis for the samples of red pepper treated by only illite were performed. Proteome analysis for red pepper showed that plastid fructose-1, 6-bisphosphate aldolase class 1, aldolase, and glyceraldehydes 3-phosphate dehydrogenase, all of which were involved in the energy metabolism, were highly expressed in leaf tissue by illite treatment. In stem tissue, NAD-dependent formate dehydrogenase involved in energy metabolism, potassium transport protein, and GIA/RGA-like gibberellins response modulator were highly expressed. Based on the results obtained from the proteome analysis, it appears that the proteins specifically and differentially expressed on the illite treatment may be involved in the enhanced growth of red pepper. The identification of some proteins involved in the response of vegetable crops to the treatment of clay mineral can provide new insights that can lead to a better elucidation and understanding of mechanism on their molecular basis.

• Journal of dental hygiene science
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• v.7 no.2
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• pp.97-100
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• 2007

In this study, to find the influencing factors of the cooperation affects the result of the orthodontic treatment, the questionnaires were collected from patients who were being treated with fixed orthodontic appliances at A dental clinic in Seoul area. The results of this study are below.1. The average of the total score of the cooperation was 8.04 with the range of between 2 and 14. 2. The gender and age of the patient did not show the meaningful significance in aspect of the cooperation. 3. The relation between the period of treatment time and the cooperation, the analysis showed that the longer the period of treatment, the lesser the cooperation (P < 0.05). 4. The average of the cooperation by decision maker, the patient himself was 9.17, mother was 7.69 and father was 7.77. This result showed that the treatment decision made by the patient himself, the cooperation was highest (P < 0.05). 5. In the relationship between the malocclusion classification and the cooperation, the Angle Class I was 8.77, Class II was 7.28, and Class III was 6.89. This result showed that the average cooperation of Angle Class I patients was higher than Angle Class III patients (P < 0.05). 6. All the influencing factors to the orthodontic treatment were analyzed by logistic regression analysis (RGA). The result showed that there is meaningful significance in the treatment period and malocclusion classification. The most influencing factor was treatment period and the longer the period, the lesser cooperation (P < 0.05).

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.122-122
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• 1999

Graphite with its advantages of high thermal conductivity, low thermal expansion coefficient, and low elasticity, has been widely used as a structural material for high temperature. However, graphite can easily react with oxygen at even low temperature as 40$0^{\circ}C$, resulting in CO2 formation. In order to apply the graphite to high temperature structural material, therefore, it is necessary to improve its oxidation resistive property. Silicon Carbide (SiC) is a semiconductor material for high-temperature, radiation-resistant, and high power/high frequency electronic devices due to its excellent properties. Conventional chemical vapor deposited SiC films has also been widely used as a coating materials for structural applications because of its outstanding properties such as high thermal conductivity, high microhardness, good chemical resistant for oxidation. Therefore, SiC with similar thermal expansion coefficient as graphite is recently considered to be a g행 candidate material for protective coating operating at high temperature, corrosive, and high-wear environments. Due to large lattice mismatch (~50%), however, it was very difficult to grow thick SiC layer on graphite surface. In theis study, we have deposited thick SiC thin films on graphite substrates at temperature range of 700-85$0^{\circ}C$ using single molecular precursors by both thermal MOCVD and PEMOCVD methods for oxidation protection wear and tribological coating . Two organosilicon compounds such as diethylmethylsilane (EDMS), (Et)2SiH(CH3), and hexamethyldisilane (HMDS),(CH3)Si-Si(CH3)3, were utilized as single source precursors, and hydrogen and Ar were used as a bubbler and carrier gas. Polycrystalline cubic SiC protective layers in [110] direction were successfully grown on graphite substrates at temperature as low as 80$0^{\circ}C$ from HMDS by PEMOCVD. In the case of thermal MOCVD, on the other hand, only amorphous SiC layers were obtained with either HMDS or DMS at 85$0^{\circ}C$. We compared the difference of crystal quality and physical properties of the PEMOCVD was highly effective process in improving the characteristics of the a SiC protective layers grown by thermal MOCVD and PEMOCVD method and confirmed that PEMOCVD was highly effective process in improving the characteristics of the SiC layer properties compared to those grown by thermal MOCVD. The as-grown samples were characterized in situ with OES and RGA and ex situ with XRD, XPS, and SEM. The mechanical and oxidation-resistant properties have been checked. The optimum SiC film was obtained at 85$0^{\circ}C$ and RF power of 200W. The maximum deposition rate and microhardness are 2$mu extrm{m}$/h and 4,336kg/mm2 Hv, respectively. The hardness was strongly influenced with the stoichiometry of SiC protective layers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.1
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• pp.57-63
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• 2011

Changes in food preferences and dietary habits of Korean prone to decrease consumption of the traditional energy source, rice. The exceeding condition of rice production in Korea is now not only impacting on the profit structure of farmers but also threatening food security. Although there have been several efforts to increase rice consumption rate, by developing various processed foods using rice flour, grain hardness of rice has been the most significant limiting factor. In this study, we addressed the suitability of the Namil(SA)-flo1, a mutant rice line has floury endosperm, in terms of producing rice flour by using dry-milling method, which is lower cost and more eco-friendly than other available methods such as wet-milling. Rice flour of the Namil(SA)-flo1 exhibited superior physico-chemical characteristics to any other check varieties including the wild type, Namil, in terms of distribution of granule sizes and content of damaged starch.