• 분석과학
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• 제7권3호
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• pp.321-327
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• 1994

7, 7-dimethyl-1, 2, 3, 4, 5-pentaphenyl-7-silanorbornadiene을 과량의 methyl alcohol과 함께 저온 열분해반응을 시켰을 때 무색 침상 모양의 결정인 1-methoxydimethylsilyl-1, 2, 3, 4, 6-pentaphenylcyclohexa-2, 5-diene이 생성되었다. 그러나 7-silanorbornadiene을 ethyl alcohol과 함께 동시 광분해반응을 시켰을 때는 silylene이 생성되어 ethyl alcohol의 O-H 결합에 삽입 반응된 ethoxydimethylsilane이 생성되었다. 이와 같은 결과로 판단해 볼 때 7-silanorbornadiene의 저온 열분해반응과 광분해반응의 반응 메카니즘이 다르다는 사실을 알았다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권9호
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• pp.429-433
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• 2006

PZT(80/0) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure was repeated 4 times. And then the PZT(20/80) precusor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5mol/L and the number of coating was varied from 0 to 6. The porosity decreased and the grain size increased with increasing the number of coatings. The thickness of the PZT-6(6: number of coatings) films was about $60{\mu}m$. The relative dielectric constant increased and the dielectric loss decreased with increasing the number of PZT(20/80) sol coatings. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 275 and 3.5%, respectively. The remanent polarization, coercive field and breakdown strength of the PZT-6 film were $19.8{\mu}C/cm^2$, 13.7kV/cm and 130kV/cm, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.354-354
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• 2011

ZnO 나노와이어는 밴드 갭이 3.37 ev로 큰 밴드 갭을 갖는 물질이며 엑시톤 결합에너지가 60 meV로 GaN(25 meV)같은 다른 반도체보다 매우 크다. 또한 밴드갭 에너지가 큰 GaN, SiC와 같은 반도체에 비해서 화학적, 열적 안정성이 크며 낮은 온도에서 성장이 가능하다는 장점이 있다. 본 연구에서는 pre-heating process를 이용하여 1차원 구조인 ZnO nanowire를 수열합성법으로 합성하였다. 실험방법으로는 E2K glass 기판위에 AZO40 nm를 증착후, 시드층으로 이용하여 ZnO nanowire를 성장하였다. precusor 전구체에는 ZN(NO3)2 ${\cdot}$ 6H2O와 Capping agent으로의 역할을 위해 PEI와 OH-source 공급을 위한 Ammonium chloride를 첨가하여 합성하였고, 그에 따른 ZnO nanowire의 morphology 및 aspect ratio를 조절하고자 하였다. 마지막으로 ZnO 나노와이어의 구조적, 광학적 특성 평가를 하기위해 XRD, FE-SEM, PL 등을 이용하여 측정 하였고, 향후 나노발전기, 태양전지 등 여러 광학기기 등에 전극재료로서 응용 가능성에 대해 알아보고자 하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제1권1호
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• pp.15-21
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• 1999

Textured bulk $YBa_2Cu_3O_x$ superconductors samples were grown directionally using different precursors of $YBa_2Cu_3O_x$ power. and a mixture of $YBa_2Cu_3O_5, BaCuO_2 and CuO$ powder. The microstructures and superconducting properties of the samples were compared. The mixture powder produced better microstructures i.e. dense and crack-free so that a higher critical current density was achieved at the same hot-zone temperature of 115$0^{\circ}C$ than the reacted powder does. When the reacted powder used as a precursor, as the hot-zone temperature increased upto 1215$^{\circ}C$, the texture of the sample improved and the critical current density increased. The amount of melt in the sample is of secondary importance for the growth of superconducting $YBa_2Cu_3O_x$ grains. The microstructures and superconductivity of good quality superconductors grown directionally were more strongly influenced by the kind of precursor rather than the amount og melt in a sample.

• 한국세라믹학회지
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• 제33권1호
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• pp.17-24
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• 1996

Pb(Mg1/3Nb2/3)O3 powder with high purity chemical homogeniety and reactivity was prepared by solvent eva-poration of common solution. The common solution was fabricated using a Pb(NO3)2 Mg(NO)3 and NB solution which was prepared by dissolving NbC in H2O2 acquous solution. In precusor powder prepared by solvent evaporation method the synthetic temperature of Pb(Mg1/3 Nb2/3)O3 phase was lowered. And the formation of homogeneous Pb(Mg1/3Nb2/3)O3 phase was enhanced but the formation of pyrochlore phase was reduced. The dielectric constant of PMN ceramics from the synthesized powder was found to increase with both sintering temperature and excess MgO and subsequent analysis of the microstructures confirmed that this was due to an increase in grain size. The grain size dependence is explained as a consequence of low-permittivity grain boundaries.

• 한국패류학회지
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• 제3권1호
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• pp.3-14
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• 1987

The electrophoretic and innunological cnalyses of organic matrices in the shells of freshwater bivalves were made in order to dlucidate the biochemical characteristics and species-specific differinces of the applied shells, The water-soluble and insoluble matrices of four species of freshwater bivalves, Andodonta fukudai, Unio douglasiae, Lanceolaria and Chrbicula fluminea, were used as analytical materials, There was non-identity in immuno affinity between anti soluble matrix(anti-Sm) and anti insoluble matrix(anti-ISM)sera against the organic matrix of Andodnta fukudai. The SMs of four species (S. fukudai, U.douglasiae, L. acrorhyncha, and C. fluminea) showed the differences in the precipitate arcs at the level of family, though ISMs did mot show differences. In the electrophoretic analysis, all foru species had two SDS-electrophoretic bands of SM, of which molecular wights appeared to be lower than 55,000, shereas the native organic matrices of foru speceis had higher molecular weighrs than those from SDS-dldctrophoresis. Only calcium ion among many ions in extrapallial fluid(EPF) caused SM to change into insoluble molecules, thus the EPF pretreated with Ca++did not form the precipitate arc when did the immuno diffusion whth anti SM serum. ISM precursor may be polymerized into macromolecules like periostracin, a precusor of periostracum, judging from the similat polymerization patterns in 0.1M Tris formate buffer(pH 3); they may be made insoluble macromolecules due to their strong natrue of hydrophobicity.

• 한국세라믹학회지
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• 제28권3호
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• pp.189-196
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• 1991

Si(OC2H5)4, commercial AlN and Y2O3 powder were used as the precusor of Si3N4, AlN, Y2O3, respectively. After Si3N4 powder was synthesized by carbothermal reduction and nitridation at 135$0^{\circ}C$ for 13h in N2 atmosphere, characteristics of synthesized powder and the ceramics sintered at 178$0^{\circ}C$ for 1h under 30MPa were investigated. In order to evaluate the reliability of sintered body, Weibull modulus was investigated. Premixing of carbon black as a reduction agent had no effect on Si(OH)4 formation, and Si3N4 powder synthesized from Si(OC2H5)4 was $\alpha$-Si3N4 single phase. Mechanical properties of sintered body were measured as follows : flexural strength ; 750MPa, fracture toughness ; 3.71Mn/3/2, hardness : 17.4GPa, thermal shock resistence temperature ; $600^{\circ}C$. Flexural strength at room temperature was 750MPa and was retained up to 110$0^{\circ}C$. The Weibull modulus of sintered body was 10.7.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.931-939
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• 1998

Preparation of the hexagonal Sr-ferrite powsers with high performance by co-spraying precusor of the FeCl$_2$+SrCO$_3$ at a low temperature was proved as a cost =-effective method. The co-spray roasting was carried out in the temperature range of 300~$700^{\circ}C$ after SrCO$_3$ powders were mixed into 12FeCi$_2$.4$H_2O$ liquor. By this low temperature roasting method fine particles of multi-phased FeO$_2$+SrCO$_3$ were formulated. Powders calcined at 105$0^{\circ}C$ for 1 hour show the best magnetic property of M\ulcorner=69.96 emu/g, M\ulcorner=36.98 emu/g, and \ulcornerH\ulcorner=4.31 Oe. This calcining temperature is lower than that of the conventional dry method by 10$0^{\circ}C$.

• 한국결정성장학회지
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• 제10권4호
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• pp.302-308
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• 2000

탄산칼슘을 모재로 한 형광체 제조를 위하여 비정질 탄산칼슘 전구체를 합성할 때 용액의 농도, 반응온도, 유지시간 및 모액의 pH의 영향을 조사함으로써 안정한 비정질 탄산칼슘을 합성할 수 있었으며, 물 속에 침적하여 결정화 조건을 달리하여 줌으로써 calcite, aragonite, vaterite의 결정 상을 얻을 수 있었다. 또한 활성원소로서 Sn을 첨가하여 비정질 탄산칼슘을 합성하고, 이를 결정화시켜 각 결정형에 따른 형광특성을 조사하였다. 결정형에 따른 발광강도는 calcite가 가장 우수하였으며, 발광중 심파장은 순수한 청색을 나타내는 464 nm였다. calcite의 발광강도는 여기파장 255 nm에서 최대가 되었으며, 형광램프용의 형광체로 사용하기 적합한 것으로 기대된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.58.1-58.1
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• 2009

나노 임프린트 리소그래피 기술은 기존의 노광 장비를 이용하는 기존의 리소그래피 공정에 비해 저렴한 공정으로 대면적 패터닝이 가능한 차세대 리소그래피 기술이다. 나노 임프린트 리소그래피는 기존의 나노 리소그래피 기술과는 다르게 기능성 무기물 물질을 직접 패터닝 할 수 있는 기술이다. 본 연구에서는 $TiO_2$ 나노 패턴을 를 기존의 증착, 리소그래피, 식각 등의 공정을 거치지 않고, sol-gel법과 나노 임프린트 리소그래피를 이용하여 직접 전사하는 기술에 대해 연구 하였다. 본 연구에서는 Tetrabutylorthotitanate를 precusor로 하는 ethanol 기반의 $TiO_2$ sol을 제작하여 이용하였다. PDMS mold를 임프린팅용 몰드로 사용하였으며, 이러한 PDMS mold는 노광 기술과 반응성 이온 식각을 이용하여 제작된 master mold로 부터 복제되었다. 제작된 sol을 Si wafer에 spin coating하여 넓게 도포한 후, wafer위에 PDMS mold를 밀착 시킨다. 이후, 5 bar의 압력과 $200^{\circ}C$의 온도에서 나노 임프린트 리소그래피 공정을 진행하여 $TiO_2$ gel 패턴을 형성한다. gel 상태의 $TiO_2$ 패턴을 anealing 공정을 통해 다결정질 TiO2 나노 패턴으로 제작하였다. 제작된 패턴을 scanning electron microscope(SEM)를 이용하여 확인하고, XRD 및 EDX를 이용하여 분석하였다.