• 한국세라믹학회지
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• 제26권1호
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• pp.37-42
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• 1989

Periodic layered domain structures in doped LiNbO3 crystals grown by Czochralski method were obtained by thermal fluctuation and crystal rotation with inhomogeneous radial temprature distribution. The stressinduced domain formation mechanism model was suggested and discussed.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2004년도 춘계총회 및 연구발표회 초록집
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• pp.27.4-27.4
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• 2004

• 세라미스트
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• 제15권3호
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• pp.24-33
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• 2012

• 한국세라믹학회지
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• 제47권2호
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• pp.132-135
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• 2010

Thermal properties of layered metal chalcogenides such as $WT_2$ (T=S,Se) with two-dimensionally disordered structure were evaluated. Thermal conductivity shows a marked decrease after exfoliation and subsequent restacking because of random stacking of two-dimensional crystalline sheet, which circumvents thermal conduction pathways along longitudinal direction in anisotropic materials.

• 한국세라믹학회지
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• 제41권1호
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• pp.41-44
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• 2004

층상구조를 갖는 점토광물은 층상의 이온교환자리에 친소수성 유기물을 화학적으로 치환할 수 있어 도자기 소지의 친소수성 정도를 조절할 수 있다. 본 연구에서는 Montmorillonite를 이온교환법으로 dodecylamine, hexadecylamine과 반응시켜 유기물이 점토광물에 복합화된 유기-점토 복합체를 조조하였다. 유기물이 점토광물 구조에 치환된 위치 및 층상구조의 간격변화는 FT-IR과 WAXD로, 수식된 유기물의 양은 TG-DSC, C/S 기기를 사용하여 조사하였다. 분석을 통하여 유기물은 층상에 선택적으로 치환하여 층간격을 증가 (12${\AA}{\leftrightarro}16{\AA}$) 시키는 역할을 하였고, 비교적 친수성을 보이는 MMT가 첨가된 가소제로 인하여 소수성으로 변하고 있음을 발견하였다.

• 한국세라믹학회지
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• 제32권7호
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• pp.761-768
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• 1995

Double layered BaTiO3 thin films with high dielectric constant as well as good insulating property were prepared for the application to low voltage driving thin film electroluminescent (TFEL) device. BaTiO3 thin films were formed by rf-magnetron sputtering technique. Amorphous and polycrystalline BaTiO3 thin films were deposited at the substrate temperatures of room temperature and 55$0^{\circ}C$, respectively. Two kinds of films prepared under these conditions showed high resistivity and high dielectric constant. The figure of merit (=$\varepsilon$r$\times$Eb.d) of polycrystalline BaTiO3 thin film was very high (8.43$\mu$C/$\textrm{cm}^2$). The polycrystalline BaTiO3 showed a substantial amount of leakage current (I), under the high electric field above 0.5 MV/cm. The double layered BaTiO3 thin film, i.e., amorphous BaTiO3 layer coated polycrystalline BaTiO3 thin film, was prepared by the new stacking method and showed very good dielectric and insulating properties. It showed a high dielectric constant fo 95 and leakage current density of 25 nA/$\textrm{cm}^2$ (0.3MV/cm) with the figure of merit of 20$\mu$C/$\textrm{cm}^2$. The leakage current density in the double layered BaTiO3 was much smaller than that in polycrystalline BaTiO3 under the high electric field. The saturated brightness of the devices using double layered BaTiO3 was about 220cd/$m^2$. Threshold voltage of TFEL devices fabricated on double layered BaTiO3 decreased by 50V compared to the EL devices fabricated on amorphous BaTiO3.

• 한국세라믹학회지
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• 제43권3호
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• pp.193-197
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• 2006

Symmetric three-layer $Al_2O_3/ZrO_2$ composite has been prepared by freeze casting and pressureless sintering at $1400-1600^{\circ}C$ in air. The layered material sintered at $1600^{\circ}C$ showed the maximum fracture strength (410 MPa), measured by a four-point bending test. Contact damage strength was superior in three-layer composite compared with corresponding mono-layered material, possibly due to the development of relatively large compressive stress. The grain growth of $ZrO_2$ particles was mainly governed by coalescence mechanism.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.223-224
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• 2006

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. This transformer has multi-layered structure. The piezoelectric transformers operated m each transformer's resonance vibration mode. The electrodes and poling directions on commercialy available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor ($k_p,\;k_{15}$) becomes effective rather than the transverse mode coupling factor ($k_{31}$). The Resonance frequency is 65.22[kHz] and maximum voltage step-up ratio is 149. Multi-layered transformer has better efficiency and step-up ratio than the single-layered transformer.

• The Korean Journal of Ceramics
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• 제4권1호
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• pp.9-14
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• 1998

Diamond-like carbon(DLC) films were deposited on buffer-layered ZnS substrates by radio frequency plasma enhanced chemical vapor deposition(RF-PECVD) method. Ge and GeC buffer layera were used between DLC and ZnS substrates to promote the adhesion of DLC on ZnS substrates. Ge buffer layers were sputter deposited by RF magnetron sputtering and $GeC^1$ buffer layers were deposited by same method except using acetylene reactive gas. The relatinship between film properties and deposition conditions was investigated using gas pressure, RF power and dc bias voltage as PECVD parameters. The hardness of DLC films were measured by micro Vickers hardness test and the adhesion of DLC films on buffer-layered ZnS substrates were studied by Sebastian V stud pull tester. The optical properties of DLC films on butter-layered ZnS substrates were characterized by ellipsometer and FTIR spectroscopy.

• 한국세라믹학회지
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• 제31권9호
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• pp.1044-1052
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• 1994

Tape casting technique was successfully applied to produce porous ceramics and multi-layered ceramics containing porous layers, where spherical hollow polymer particles were introduced as pore precursors. In the presence of extreme differences in density and size between Al2O3 and pore precursor particles, hindered settling was effective in preventing segregation of component particles and packing behavior of mixed powders was improved through bimodal packing. There were two transitions in packing behavior of mixed powders. The first transition took place at 40~50 vol% pore precursor addition, where majority of pores changed from close to open pore state. The other transition occured at 60~70 vol% pore precursor addition, where pore precursor particles formed a continuous network structure.