• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.994-1000
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• 2003

In this study, gel polymer electrolytes (GPE) with semi-interpenerating network of poly (methyl methacrylate) and hexanediol dimethacrylate were synthesized and their electrochemical performances were evaluated. LiCoO$_2$/GPE/graphite cells were prepared and their performances depending on discharge currents and temperatures were evaluated. The precursor containing 5 vol% curable mixture had a low viscosity relatively. GPE showed good electrochemical stability up to potential of 4.8 V vs. Li/Li$\^$+/. Ionic conductivity of the gel polymer electrolyte at room temperature and -20$^{\circ}C$ was ca. 5.9 and 1.4${\times}$10$\^$-3/ Scm$\^$-1/, respectively. LiCoO$_2$/GPE/graphite cells showed good rate capability, low-temperature performance and cycleability.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2030-2032
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• 1998

It is always necessary to high performance power supplies for the magnet system in the accelerator, especially when the number of power supplies are large. When have developed the compact power supply using switching technology instead of SCR phase control. We adopt the pulse width modulation(PWM) method with a half bridge DC/DC converter. In this way, we can make a compact system with light weight and small volume. Actual system we developed is 1.2kW, 35V/35A bipolar DC power supply current precision of +/-0.02%. It is possible to mount 10 unit in a conventional 19 rack. The built in controller has an RS422 protocol to drive 10 unit by one serial port up to 1.2km distance. If we adopt RS485 protocol, one serial port can control 32 power supplies. In this paper, we will report the design and performance of the prototype power supply.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.581-584
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• 2002

A new method for the preparation of lanthanide ions activated strontium aluminates phosphor by combustion method has been proposed. Combustion method consist of the redox reactions between the respective metal nitrates and urea in a preheated funace at $500^{\circ}C$. The luminescence behavior of the phosphor was studied and compared with corresponding phosphor prepared by conventional method. Effect of $Mg^{2+}$ ion concentration in strontium aluminate phosphor was investigated and the maximum luminescence of about $100cd/m^2$ was obtained. This method gave better brightness and small size to the phosphor than made by conventional method.

• Carbon letters
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• v.6 no.2
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• pp.96-100
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• 2005

Taguchi methodology has been applied to get an idea about the parameters related to the chemical vapour deposition technique, which influences the formation of semiconducting carbon thin film of a desired band gap. L9 orthogonal array was used for this purpose. The analysis based on Taguchi methodology suggests that amongst the parameters selected, the temperature of pyrolysis significantly controls the magnitude of band gap (46%). Sintering time has a small influence (30%) on the band gap formation and other factors have almost no influence on the band gap formation. Moreover this analysis suggests that lower temperature of pyrolysis (${\leq}$ $750^{\circ}C$) and lower time of sintering (${\leq}$ 1 h) should be preferred to get carbon thin film with the desired band gap of 1.2eV.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.75-83
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• 1995

In-situ, 실시간 측정을 위해 상업화 모형의 He-Ne 타원해석기 및 고속 분광 타원해석기(SE, Spectoscopic Ellipsometer)를 제작하였다. 후자의 경우 1024개의 화소를 가진 광학 다채널분석기 (OMA, Optical Multichannel Analyzer)를 이용한 RP형 분광타원해석기로써 1.5∼5.0eV의 측정 파장대역을 가지며, 한 스펙트럼의 측정시간은 약 100msec이다. cos 와 tanΨ의 정확도는 각각 약0.01이하로 측정되었다. 이러한 in-situ 타원해석기들을 사용하여 Au, ZnS 박막들의 성장 초기단계에서의 박막구조의 변화, 성장속도 그리고 HF식각후의 Si 자연산화층(SiO2)의 초기 성장과정을 밝히고 SiO2/c-Si 시료의 온도를 비 접촉적, 비간석적으로 기존의 방법에 의한 결과와 비교하였다.

• Mycobiology
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• v.31 no.4
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• pp.209-213
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• 2003

Aspergillus flavus K-03 isolated from poultry forming soil in Korea was studied for its ability to produce extracellular proteases on basal medium containing 2%(w/v) chicken feathers. The fungus was observed to be a potent producer of such enzymes. Keratinolytic enzyme secretion was the best at 15 days of incubation period at pH 9 and temperature $40^{\circ}C$. No relationship existed between the enzyme yield and increase of biomass. Enzyme production was suppressed by exogenous sugars in descending order arabinose>maltose>mannose>fructose. But glucose did not influence the enzyme activity. The keratinolytic enzyme released by the fungus demonstrated the ability to decompose keratin substrates as chicken feather when exogenous glucose was present. The keratinolytic activity was inhibited by $HgCl_2$ and serine-protease inhibitors such as phenymethylsulfonyl fluoride(100%), chymostain(88%), crystalline soybean trypsin inhibtor(80%), antipain(45%) and aprotinin(40%), and was not by cystein-protease and aspartyl-protease inhibitors. The enzyme activity is only partially inhibited by metallo-protease inhibitor. Thus, the enzyme secreted by A. flavus K-03 belongs to the alkaline serine-type protease.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.342-342
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• 2011

산화막은 반도체 공정 중 가장 핵심적이며 기본적인 물질이다. 반도체 소자에서 내부의 캐리어들의 이동을 막고 전기를 절연시켜주는 절연체로서 역할을 하게 된다. 실제로 제작된 산화막에서는 dangling bond 혹은 내부에 축적되는 charge들의 의해 leakage가 생기게 되고 그에 따라 산화막의 특성은 저하되게 된다. 내부에서 특성을 저하시키는 defect을 감소시키기 위해 Plasma Treatment에 따른 특성변화를 관찰하였다. 본 연구에서는 최적화 시킨 Flexible TFT제작을 위해 저온에서 Silicon Oxide로 형성한 Gate Insulator에 각각 N2O, H2, NH3가스를 주입 후 Plasma처리를 하였다. 특성화 시킨 Gate Insulator를 이용하여 MIS(Metal-Insulator-Semiconductor)구조를 제작 후 C-V curve특성변화, Dit의 감소, Stress bias에 따른 stability를 확인 하였다.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.95-98
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• 1998

완화형 강유전체인 0.9MPb*Mg$_{1}$3/Nb$_{2}$3/)O$_{3}$-0.1PbTiO$_{3}$에서 강유전-상유전 상전이에 수반되는 relaxation거동을 살펴보기위해 낮은 전계에서 측정된 유전특성과 높은 전계에서 측정된 전계유기 분극 거동 등을 조사하였다. -50-9$0^{\circ}C$의 상전이 온도범위에 걸쳐 1V/mm의 낮은 전계에서 측정된 유전특성의 온도의존성을 구하고 수 kVmm의 강전계하에서 발생된 분극의 온도의존성을 관찰하였다. 이 모든 결과들은 Vogel-Fulcher관계식에 비교적 정확하게 일치되었으며 그 결과 T$_{f}$ 는 294.6˚K로 나타났다. 본 연구결과를 통하여 Vogel-Fulcher관계식에 의한 주파수 의존성은 낮은 전계하에서의 유전특성 뿐 아니라 강전계하에서의 여러물성들도 동일하게 적용되는 것을 확인할 수 있었다.

• Journal of the Semiconductor & Display Technology
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• v.2 no.4
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• pp.27-30
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• 2003

The effect of fabrication method of catalytic layer on electrode performance has been investigated. Brush, spray gun and screen printer were used as fabrication tool and catalytic layers were formed by several methods in screen printing. Direct screen printing on polymer membrane, screen printing on carbon paper, and their combined method were applied. In the electrode fabricated by the screen printing method, Pt loading of Pt/C catalysts could be cut down to 50%, compared with results by the brushing and spraying methods. The best result of electrode was obtained as 0.6 V, at 1 A/$\textrm{cm}^2$ when catalytic layer was formed by the combined way.

• Korean Journal of Human Ecology
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• v.7 no.2
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• pp.31-46
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• 2004

The purpose of this study was to investigate the physiological functionality of Coriolus versicolor Quel (CV) and Ganoderma IUCIdum (Fr.)Karst (GL) by estimate the proximate composition and content of antioxidant components. 1. In the physicochemical property. the content of proximate composition of GL was higher 08.28% of moisture, 10.3% of crude protein, 78.4% of crude fiber) than that of CV, but the content of crude lipid and ashes of GL was higher than that of CV. 2. CV had relatively higher content of antioxidant components such as total phenol, carotenoids and v itamin C. than GL did. Antioxidant mineral components such as magnesium and zinc also had relatively higher in CV than in GL. 3. TBA value, conjugated diene production, LDL oxidation, DPPH of methanol extracts in CV and GL were as high as a-Tocopherol.