• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.126-126
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• 2000

다이아몬드상 카본(DLC) 필름은 경도가 높고, 마찰계수가 낮다는 장점을 가지고 있기 때문에 내마모성 코팅이나 윤활성코팅에 응용을 위한 연구가 활발히 진행중이다. 하지만 마찰계수가 주변환경에 매우 큰 영향을 받는다는 단점이 있다. 이러한 단점은 DLC필름의 응용에 대한 저해 요인이 되며, 이 점을 보완하기 위해서 DLC 필름에 Si을 첨가하는 연구들이 진행되고 있다. 본 실험에서는 r.f-PACVD 법을 이용하여 Si이 첨가된 DLC 필름의 주위 환경 변화에 따른 마찰특성의 변화를 연구하였다. 사용한 반응 가스는 벤젠(C6H)과 희석된 Silane(SiH4 : H2 = 10 : 90)이며, 희석된 Silane과 벤젠의 첨가비율을 조절하여 필름내 Si의 함량을 조절하였고, 증착시 바이아스의 전압은 -400V로 하였다. 마찰테스트는 Ball-on-Disk type의 조건에서 대기, 건조공기, 진공의 세가지 분위기에서 마찰테스트를 실행하였다. 실험결과 마찰계수는 건조공기, 대기, 진공의 순으로 증가하였고, 필름내에 포함되어 있는 Si의 양이 증가할수록 마찰계수는 낮고 안정한 값을 나타내었다. Tribochemiacal 분석과, ball과 track의 전자현미경 사진 분석 결과, 진공에 비해서 건조공기와 대기중에서 마찰계수가 낮은 것은 DLC 필름내에 마모 track 중심부에 Si-C-O 계의 화합물이 형성되어, 이 화합물이 마찰계면에 존재하여 마찰계수를 낮추었음을 확인하였다. 그리고 대기중에서 실험한 경우, 습기의 존재로 인해 마모입자가 볼의 표면에서 엉김으로써 건조공기의 상태에서 보다 높은 마찰저항을 갖게 됨으로 인하여 마찰계수가 높아짐을 알 수 있었다.a)는 as-deposit 상태이며, 그림 1(b)는 45$0^{\circ}C$, 60min 열처리한 plan-view TEM 사진이다.dical의 영향을 조사하였으며 oxygen radical의 rf power에 따른 변화는 OES(Optical emission spectroscopy)를 사용하였다. 너무 적은 oxygen ion beam flux나 oxygen radical은 film의 전도도 및 투과도를 저하시켰고 반면 너무 과도한 flux의 증가 시는 전도도는 감소하였고 투과도는 증가하는 경향을 보였다. 기판에 도달하는 oxygen ion flux는 faraday cup을 이용하여 측정하였으며 증착된 ITO film은 XPS, UV-spectrometer, 4-point probe를 이용하여 분석하였다. 때문으로 생각되어진다. 또한, 성장 온도가 낮아짐에 따라 AlGaN의 성장을 저해하기 때문으로 판단된다. 성장 온도 변화에 따라 성장된 V의 구조적 특성 및 표면 거칠기 변화를 관찰하여 AlGaN의 성장 거동을 논의하겠다.034, 0.005 정도로 다시 감소하였다. 박막의 유전율은 약 35 정도의 값을 나타내었으며 X-선 회절 data로부터 분석한 박막의 변형은 증온도에 따라 7.2%에서 0.04%로 감소하였고 이 이경향은 유전손실은 감소경향과 일치하였다.는 현저하게 향상되었다. 그 원인은 SB power의 인가에 의해 활성화된 precursor 분자들이 큰 에너지를 가지고 기판에 유입되어 치밀한 박막이 형성되었기 때문으로 사료된다.을수 있었다.보았다.다.다양한 기능을 가진 신소재 제조에 있다. 또한 경제적인 측면에서도 고부가 가치의 제품

• Journal of Conservation Science
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• v.12 no.1 s.15
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• pp.48-70
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• 2003

The characterization of chemical properties and analogy of mallufactured origin for the nine potsherds and eleven celadon sherds collected in Wonnae-dong, Daejeon and Yucheon-ri, Buan, respectively were performed by analyzing their body and glaze compositions and compared with previous data reported. The chemical compositions of the body and glaze were determined by XRF and EPMA, respectively. The trace elements of the body were analyzed by ICP-MS. The Seger analysis and principal components analysis were used to compare the major compositions of body and glaze of the potteries we found with previous data. Wonnae-dong's Whiteware (C-1) showed considerably high $SiO_2$ concentration differently from the other potteries. Wonnae-dong's Whiteware (C-2) showed similar characteristics with potteries of Seoul-Kyeongi and Daejeon-Chungnam provinces in chemical compositions of the body and the glaze. Wonnae-dong's celadons (B-1 and B-2) were classified as the group of Daejeon, Chungman provincial potteries in chemical compositions of the body. It was difficult to distinguish the characteristic differences in the Buncheong data between the provinces with the Seger formula analysis and the PCA. Celadon from Yucheon-ri site showed the same characteristics with previous data reported. The results above demonstrated that it is reasonable to study the characterization of potteries and analogy of manufactured origin with a comparison for the chemical compositions of the body and the glaze of the potteries by using the Seger formula analysis and the PCA.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1267-1268
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• 2008

The two-shot SLS method has recently been successfully implemented in volume manufacturing of advanced LTPS-based LCDs. In this presentation, we discuss how the approach is also well suited for being implemented in high-throughput and high-yield manufacturing of large AMOLED displays on large glass substrates.

• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.107-114
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• 1993

Zinc-Borosilicate(ZnO 65.0wt%, B2O3 21.5wt%, SiO2 9.0wt%, PbO or tiO2 4wt%) passivation glasses were studied using differential thermal analysis(DTA), scanning electron microscopy(SEM) observations, X-ray diffraction (XRD) patterns and measurement of thermal expansion coefficients. Passivation glasses containing 4wt% TiO2 and 4wt% PbO had crystallization temperature of 680~73$0^{\circ}C$ and major crystalline phases were identified by X-ray diffraction as $\alpha$-ZnO.B2O3 and $\alpha$-5ZnO.2B2O3. As increasing firing temperature, the size of crystalline phases increased by observation of SEM. The thermal expansion coefficient of crystallized glass frits was smaller than that of unfired glass.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.581-586
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• 2001

The potential anticancer agents, new anthracycline analogues (2-9) have been synthesized from the glycosides daunomycin (1a) and doxorubicin (1b). Compounds 2 and 6 were prepared by nucleophilic displacement esterification of a 14-bromodauomycin(1c) with sodium or potassium salts of butyric and all trans retinoic acid, respectively. Compounds 3 and 7 were obtained from daunomycin (1a) by direct amidation with a butyric and all trans retinoic acid in the presence of EDCI and PP, respectively. Compounds 4 and 8 were obtained from doxorubicin (1b) by reaction with the corresponding acids in the same manner. Compounds 5 and 9 were prepared from doxorubicin (1b) by acylation with two equivalents of the corresponding acids under the same reaction conditions.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.587-592
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• 2001

The potential anticancer agents new anthracycline derivatives (2~9) have been synthesized from daunomycin (1a) and doxorubicin (1b) ad starting materials. Compounds 2 and 6 were prepared by the nucleophilic displacement type esterification of a 14-bromodaunomycin (1c) with a acetylsalicylic and palmitic acid in triethylamine, respectively. Compound 3 and 7 were obtained from daunomycin (1a) by direct amidation with the corresponding acids in the presence of EDCI and PP as esterification regents. Whereas 4 and 8 were prepared by reaction of doxorubicin (1b) with one equivalent of acetylsalicylic and palmitic acid using DCC/DMAP, respectively, 5 and 9 were obtained from 1b by acylation with two equivalents of the corresponding acids using EDCI/PP reagents.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1545-1547
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• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta$-Sic-$TiB_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of $Al_{2}O_{3}+Y_{2}O_3$. Phase analysis of composites by XRD revealed $\alpha$-SiC(6H), $TiB_2$, and YAG($Al_{5}Y_{3}O_{12}$). The relative density and the mechanical properties of composites were increased with increasing $Al_{2}O_{3}+Y_{2}O_3$ contents because YAG of reaction between $Al_{2}O_3$ and $Y_{2}O_3$ was increased. The Flexural strength showed the highest value of 432.5MPa for composites added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature. Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism. the fracture toughness showed 7.1MPa${\cdot}m^{1/2}$. For composites added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature The electrical resistivity and the resistance temperature coefficient respectively showed the lowest of 6.0${\sim}10^{-4}{\Omega}{\cdot}$ cm and 3.1${\times}10^{-3}/^{\circ}C$ for composite added with l2wt% $Al_{2}O_{3}+Y_{2}O_3$ additives at room temperature. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of 25$^{\circ}C$ to 700$^{\circ}C$.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.64-68
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• 2010

Cattle feedlot manure could be used effectively as the solid fuel for heating of agricultural facilities. Therefore, this study was carried out to investigate the thermal and physicochemical characteristics of solid fuel extruded with cattle feedlot manure. Calorific values of the solid fuel extruded with cattle feedlot manure, which was dried to the moisture contents of 0.0% (w.b) and 35.0% (w.b,) were 14,906 kJ/kg and 11,797 kJ/kg, respectively. Calorific value of extruded solid fuel was linearly decreased with the increase of moisture content. The first, second, and third reaction point during thermal pyrolysis of solid fuels extruded with cattle feedlot manure was investigated as $108.1^{\circ}C$, $312.2^{\circ}C$, and $459.4^{\circ}C$, respectively. The maximum reaction point was presented at the temperature of $312.2^{\circ}C$. Weight loss of extruded cattle feedlot manure during thermal pyrolysis until $600^{\circ}C$ was reached to about 60%. Volume decrease of initial extruded cattle feedlot manure was 61% during drying for the use as solid fuel. Maximum strength of extruded cattle feedlot manure, which was dried as the moisture content of 10% (w.b.) was 41,9150 N/$m^2$. Ignition gas analysis of extruded cattle feedlot manure presented that it has small amount of $NO_x$ and $SO_x$. It was shown that dried cattle feedlot manure had main components of C and O including small amount of Mg, Si, and Ca.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.33.2-33.2
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• 2011

고온형 SOFC의 개발에 있어 스택의 신뢰성을 확보하는데 가장 중요한 핵심기술은 스택 구성요소 사이를 접합하는데 필요한 고온형 밀봉재의 개발이다. SOFC 스택에서의 밀봉재는 고체전해질과 접속자 사이에서 음극에 공급되는 연료가스와 양극에 공급되는 공기가 서로 혼합되는 것을 방지하는 역할은 물론 기계적으로 취약한 단전지의 보호 및 스택전체 구조물의 구조적 일체성(Structural integrity)을 부여하는데 주목적이 있다. 현재 기체 기밀성을 유지하기 위한 밀봉재는 크게 유리 및 결정화 유리계, mica및 mica/유리복합재료, 유리/충전재 복합재료 등이 사용되고 있으나 다수의 단위전지로 구성되는 스택 구성에서 스택의 열기계적 안정성 및 장기수명을 보장하기 위해서는 본 연구에서 개발하고자 하는 복합밀봉재가 가장 적합할 것으로 예상되고 있다. 본 연구에서는 $SiO_2-B_2O_3-RO$계에 BaO, SrO를 일정비율로 첨가하여 제작된 유리 frit을 열처리하여 물리화학적 물성변화를 검토하였으며, $700^{\circ}C$ 이하의 연화점을 갖는 유리를 기지상으로 하고 세라믹 보강재를 첨가한 고온형 복합밀봉재를 개발하고 그 물리화학적 안정성, 열기계적 안정성 및 밀봉 특성을 평가하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.250-254
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• 2003

A film bulk acoustic resonator (FBAR) device for 2 GHz radio frequency (RF) bandpass filter application is presented. This FBAR device consists of an aluminum nitride (AlN) film sandwiched between top(Al) and bottom(Au) electrodes and an acoustic multilayer reflector of a silicon dioxide/tungsten (SiO2/W). The A/N film deposited using a RF sputtering was observed to have small columnar grains with a strongly preferred orientation towards c axis. In addition to a high quality factor (4300), a large return loss of 37.19 dB was obtained.