• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.199-199
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• 2013

최근 단파장 광전 소자와 고출력 고주파 전자 소자에 대한 수요 때문에 넓은 밴드갭 에너지를 갖는 반도체에 관심이 많다. 이중에서, ZnO는 우수한 화학 및 역학적 안정성, 수소 플라즈마 내구성과 저가 제조의 장점 때문에 광전자 소자 개발 분야에 적합한 산화물 투명 전극으로 관심을 끌고 있다. 불순물이 도핑되지 않은 ZnO는 본질적으로 산소 빈자리 (vacancy)와 아연 격자틈새 (interstitial)와 같은 자체의 결함으로 말미암아 n형의 극성을 갖기 때문에, 반도체 소자로 응용하기 위해서는 도핑 운반자의 농도와 전도성을 제어하는 것이 필요하다. 본 연구에서는 박막 제조시 제어성, 안정성과 용이하게 성장이 가능한 졸겔 (sol-gel) 방법을 사용하여 사파이어와 석영 기판 위에 Cu가 도핑된 ZnO 박막을 성장시켰으며, 그것의 구조, 표면 형상, 평균 투과율, 광학 밴드갭 에너지를 계산하였다. 특히, Cu의 몰 비를 0, 0.01, 0.03, 0.05, 0.07, 0.1 mol로 변화시키면서 ZnO:Cu 박막을 성장시켰다. ZnO:Cu 졸은 zinc acetate dihydrate, 2-methoxyethanol (용매), momoethanolamine (MEA, 안정제)을 사용하여 제조하였다. 상온에서 2-methoxyethanol과 MEA가 혼합된 용액에 zinc acetate dihydrate (Zn)을 용해시켰다. 이때 MEA와 Zn의 몰 비는 1로 유지하였다. 이 용액을 $60^{\circ}C$ 가열판 (hot plate)에서 24 h 동안 자석으로 휘젓으며 혼합하여 맑고 균일한 용액을 얻었다. 이 용액을 3000 rpm 속도로 회전하는 스핀 코터기의 상부에 장착된 사파이어와 석영 기판 위에 주사기 (syringe)를 사용하여 한 방울 떨어뜨려 30 s 동안 스핀한 다음에, 용매를 증발시키고 유기물 찌꺼기를 제거하기 위하여 $300^{\circ}C$에서 10분 동안 건조시킨다. 기판 위에 코팅하는 작업에서 부터 건조 작업까지를 10회 반복한 다음에, 1 h 동안 전기로에 장입하여 석영 기판 위에 증착된 시료는 $550^{\circ}C$에서, 사파이어 기판은 $700^{\circ}C$에서 열처리를 수행하였다. Cu의 몰 비 0, 0.01, 0.03, 0.05, 0.07, 1로 성장된 ZnO:Cu 박막에 대한 x선 회절 분석의 결과에 의하면, 모든 ZnO:Cu 박막의 경우에 관측된 34.3o의 피크는 ZnO (002) 면에서 발생된 회절 패턴을 나타낸다. 이것은 JCPDS #80-0075에 제시된 회절상과 일치하였으며, ZnO:Cu 박막이 기판에 수직인 c-축을 따라 우선 배향됨을 나타낸다. 사파이어 기판 위에 증착된 박막의 경우에, Cu의 몰 비가 점점 증가함에 따라(002)면 회절 피크의 세기는 전반적으로 증가하여 0.07 mol에서 최대를 나타내었으나, 석영 기판 위에 증착된 박막의 경우에는 0.05 mol에서 최대를 보였다. 외선-가시광 분광계를 사용하여 서로 다른 Cu의 몰 비로 성장된 ZnO:Cu 박막에서 광학 흡수율 (absorbance) 스펙트럼을 측정하였으며, 이 데이터를 사용하여 평균 투과율을 계산한 결과, 투과율은 Cu의 몰 비에 따라 현저한 차이를 나타내었다. Cu의 몰 비가 0.07 mol일 때 평균 투과율은 80%로 가장 높았으며, 0.03 mol에서는 30%로 최소이었다. 광학밴드갭 에너지는 Tauc 모델을 사용하여 계산하였고, 결정 입자의 형상과 크기와의 상관 관계를 조사하였다.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.1085-1093
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• 2017

Plasticizers are materials added to give softness and elasticity to plastics having rigid properties to give soft properties as products, and they are mainly added to high molecular materials to give flexibility to improve workability and to improve cold resistance, resistance to volatility and electrical properties. It is used for the purpose. Most plasticizers are inert liquids, similar in function to solvents but with high molecular weight and no volatility. In addition, when dissolved in petrochemical products, only the plasticizer is separated by the matrix effect with other compounds, and qualitative and quantitative analysis. In this study, qualitative and quantitative analysis of DOA and DOP, which are representative components of petrochemical products, were conducted using MD-GC/MS and developed an optimal plasticizer analysis method.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.395-399
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• 2011

Material of the gasket for lithium ion battery requires the chemical resistance, the electrical insulting property, the compression set, the anti-contamination level and the low temperature resistance. We compounded ethylene propylene diene monomer (EPDM), which showed widely different solubility parameter index, with adjusting the amount of metal oxide as an activator. We did long-term test and compression set against an electrolyte with consideration for operating conditions in lithium-ion battery. In these tests, we checked the physical, chemical characteristics and the effect to lithium ion battery with different kinds of activators. In case of rubber with ZnO as an activator, through 1000 h depositing test in propylene carbonate which is one of representative solvents, we could get the satisfying characteristics and result. However, $Zn^{2+}$ had eluted in the ion elution test. So, ZnO should be limited in EPDM compound for the gasket material in lithium-ion battery.

• Analytical Science and Technology
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• v.20 no.5
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• pp.393-399
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• 2007

In principle, the blood galactose level may be determined conveniently with a strip-type biosensor similar to that for glucose. In this study, we describe the development of a disposable galactose biosensor strip for point-of-care testing. The sensor strip is constructed with screen-printed carbon paste electrode (SPCE) and sample amount (< $100{\mu}L$). The developed strip the galactose level in less than 90 s using bienzymatic system of galactose oxidase (GAO) and horseradish peroxidase (HRP). The effects of pH, mediator (1,1-ferrocenedimethanol) concentration, ratio of enzymes, and applied potential were determined preliminarily with glassy carbon electrodes, and optimized further with the strip-type electrodes. The sensor exhibits linear response in the range of $0{\sim}400{\mu}M$ ($r^2$ = 0.997, S/N = 3). Since a low working potential, in principle, the fabricated disposable galactose biosensor has -100 mV (vs. Ag/AgCl), it is applied for the detection of galactose, interfering responses from common interferents such as ascorbic acid, uric acid and acetaminophen could be minimized. The sensor has been used to determine the total galactose level in standard samples with satisfactory reproducibility (CV = 5 %).

• Journal of Life Science
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• v.17 no.12
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• pp.1701-1708
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• 2007

Seed pelleting is generally conducted in order to save the labor for sowing and thinning by enabling the precision mechanical planting. In the present study, the influence of physical and chemical properties of pelleting solid materials was investigated on carrot seed germination. Among the pelleting solid materials evaluated, dialite, kaolin, and talc showed low bulk density and high porosity. Bentonite and dialite carried high water holding capacities of 184% and 173%, respectively, while calcium carbonate, calcium oxide, and fly ash showed relatively low water holding capacity. The pH of kaolin (6.8) and dialite (7.4) were close to neutral, while limestone (12.8), calcium oxide (13.0), and bentonite (10.0) were highly basic. High electro-conductivity was shown in limestone and calcium oxide. EDS analysis revealed that the main elemental compositions of talc were Si (71.0%) and Mg (29.0%), and those of calcium carbonate were Ca (66.6%), Si (22.9%), and Mg (10.5%). High granulation capacity was observed from talc and the mixture of talc and calcium carbonate. Seeds pelleted with bentonite showed the highest hardness. The dissolving type of the pellet layer after imbibition was split type in talc, limestone, zeolite, and fly ash, melt type in calcium carbonate and calcium oxide, and swell type in bentonite and vermiculite. The shortest dissolving time of pellet layer was observed from calcium carbonate and kaolin. The germination speed $(T_{50})$ was delayed as the size of pelleted seeds increased. The optimum size of pelleting was 19 ratio in carrot.

• Journal of Gifted/Talented Education
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• v.12 no.2
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• pp.1-15
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• 2002

The purpose of this study was to investigate the characteristics of preschoolers' giftedness by their parents' perception. Total 3 groups of 148 subjects from age 30 months to 6 years 10 months old young gifted children's parents participated. The major findings were as follows : (1) There were critical characteristics of preschoolers' giftedness by parents' perception, which were 'good memory', 'high curiosity', 'read and understand of math', 'enjoy of learning and high motivation', 'high concentration', reading books', 'verbal ability', 'creativity', 'questions', and 'independency', (2) These characteristics of preschoolers' giftedness showed more strong and intense as they got older, and (3) Some characteristics revealed more, but the other characteristics revealed less as they got older. These findings suggested the consideration of child's age as the reliable identification process of young gifted children.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.333-339
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• 2009

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included. Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 ${\mu}m$) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%. Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/$cm^2$. Teeth were thermocycled fivehundred times between $50^{\circ}C$and $550^{\circ}C$for 30s at each temperature. Electrical conductivity (${\mu}A$) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method. Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (${\mu}A$)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41). Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.128-132
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• 1983

The apple seed contained 25.96% of crude fat and 37.62% of crude protein. The lipid fractions obtained by cilicic column chromatography were mainly composed of about 93.52% neutral lipid, whereas compound lipid was only 6.48% level. Among the neutral lipid separated by thin layer chromatography, triglyceride was 92.17%, sterol ester, sterol, diglyceride and free fatty acid were 3.53, 2.25, 1.44 and 0.56, respectively. The predominent fatty acids of total and neutral lipids were linoleic acid (59.79-69.37%) and oleic acid (20.04-29.82%), but those of glycolipid and phojspholipid were linoleic acid (29.20-36.04%). The major fatty acids of triglyceride separated from neutral lipid were oleic acid (44.31%), linoleic acid (36.66%) and palmitic acid (12.48%). The salt soluble protein of apple seed was highly dispersible in 0.02M sodium phosphate buffer containing about 1.0M $MgSO_4$, and the extractability of seed protein was 37%, Glutamic acid was the major amino acid in salt soluble protein, followed by arginine and aspartic acid. The eletrophoretic analysis showed three bands in apple seed protein, and the collection rate of the main protein fraction purified by Sephadex G-100 and G-200 was 76.6%. Glutamic acid, aspartic acid and arginine were the major amino acids of the main apple seed protein. The molecular weight for the main protein of the apple seed was estimated to be 45,000.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.1
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• pp.46-50
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• 1983

In order to find out the possibility of utilizing red pepper seed as food resources of fats and proteins, a series of studies were conducted. The red pepper seed contained 27.6% of crude fat and 22.2% of crude protein. The lipid fractions obtained by silicic acid column chromatography were mainly composed of 95.4% neutral lipid, where as compound lipid were 4.6%. Among the neutral lipid separated by thin layer chromatography, triglyceride was 85.6%, sterol ester 4.9%, free fatty acids 3.4%, diglyceride 2.5%, sterol 2.2% and monoglyceride 1.1%, respectively. The predominant fatty acids of red pepper seed oil were linoleic acid (57.1-75.4%), palmitic acid (13.9-21.3%) and oleic acid (8.0-15.1%), especially glycolipid contained 1.7% of linolenic acid and small amount of myristic acid and arachidic acid. The salt soluble protein of red pepper seed was highly dispersible in 0.02M sodium phosphate buffer containing 1.0M $MgSO_4$, and the extractability of seed protein was about 25.0%. Glutamic acid and arginine were major amino acids of red pepper seed protein. The electrophoretic analysis showed 6 bands in seed protein, and the collection rate of the main protein fraction purified by sephadex G-100 and G-200 was about 62.2%. Glutamic acid (19.9%) was major amino acid of the main protein, followed by glycine and alanine. The molecular weight of the main protein was estimated to be 93,000.

• Korean Journal of Food Science and Technology
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• v.14 no.3
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• pp.250-256
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• 1982

A series of studies were conducted to find out the possibility of utilizing grape seed as resources of food fats and proteins, and the results of the studies are as follows: The grape seed contained 25.1%, of crude fat and 12.0% of crude protein. The lipid, fractions obtained by silicic acid column chromatography were mainly composed of about 95.5% neutral lipid, whereas compound lipid was only 4.5% level. Among the neutral lipid by thin layer chromatography, triglyceride was 91.89%, sterol ester, sterol, diglyceride and free fatty acid were 3.24%, 2.87%, 1.20% and 0.80%, respectively The predominant fatty acids of total and neutral lipids were linoleic acid $(69.72{\sim}71.72%)$ and oleic acid $18.09{\sim}19.46%)$, but those of glycolipid and phospolipid were linoleic acid $(31.49{\sim}38.18%)$, oleic acid $(20.20{\sim}35.27%)$ and palmitic acid $(26.80{\sim}39.98%)$. The major fatty acids of triglyceride separated from neutral lipid were oleic acid (43.08%), linoleic acid (38.42%) and palmitic acid (11.60%). The salt soluble protein of grape seed was highly dispersible in 0.02M sodium phosphate buffer containing about 1.0M $MgSO_4$, and the extractability of seed protein was 31%. Glutamic acid was the major amino acid in salt soluble protein, followed by arginine and aspartic acid. The electrophoretic analysis showed 3 bands in grape seed protein, and the collection rate of the main protein fraction purified by Sephadex G-100 and G-200 was 82%. Glutamic acid, aspartic acid and arginine were the major amino acids of the main grape seed protein. The molecular weight for the main protein of the grape seed was estimated to be 81,000.