• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.456-459
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• 2000

Thin films of vanadium oxide(V$O_x$) have been deposited by r.f. magnetron sputtering from $V_2$$O_5$ prget in gas mixture of argon and oxygen. Crystal structure, surface morphology, chemical composition and bonding properties of films in-situ annealed in $O_2$ ambient with various heat-treatment conditions are characterized through XRD, SEM, AES, RBS and FTIR measurements. The filrns annealed below 200 $^{\circ}C$are amorphous, and those annealed above 30$0^{\circ}C$ are polycrystalline. The growth of grains and the transition of vanadium oxide into the higher oxide have been obsenred with increasing the annealing temperature and time. The increase of O/V ratio with increasing the annealing temperature and time is attributed to the diffusion of oxygen and the partial filling of oxygen vacancies. It is observed that the oxygen atoms located on the V-0 plane of $V_2$$O_5$ layer participate more readily in the oxidation process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.56-61
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• 1999

Highly conductive oxide films of BaRuO$_3$ have been grown heteroepitaxially on (100) LaAlO$_3$ single crystalline substrates by using pulsed laser deposition. The films are c-axis oriented with an in-plane epitaxial relationship of <010><100>BaRuO$_3$ // <110>LaAlO$_3$. Atomic force microscopy (AFM) observation shows that they consist of a fine-arranged network of grains and have a mosaic microstructure. Generally temperature-dependent resistivity shows the transition from metallic curve to semiconductor-metallic twofold curve by the deposition conditions for Ru oxide based materials like SrRuO$_3$, CaRuO$_3$, BaRuO$_3$, etc.. This twofold curve comes from the structural similarity of Ru oxide based materials including BaRuO$_3$. We find that the distance of Ru-Ru bonding in the unit cell of BaRuO$_3$ as well as the grain boundary scattering could be the two important causes of these interesting conductive properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.267-270
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• 2004

A silver indium sulfide($AgInS_2$) epilayer was grown by the hot wall epitaxy method, which has not been reported in the literature. The grown $AgInS_2$ epilayer has found to be a chalcopyrite structure and evaluated to be high qualify crystal. From the photocurrent measurement in the temperature range from 30 K to 300 K, the two peaks of A and B were only observed, whereas the three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks. are ascribed to the band-to-band transition. The valence band splitting of $AgInS_2$ was investigated by means of the photocurrent measurement. The crystal field splitting, $\ddot{A}cr$, and the spin orbit splitting, $\ddot{A}so$, have been obtained to be 0.150 eV and 0.009 eV at 10 K, respectively. And, the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, $E_g(T)$, was determined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.55-58
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• 2003

[ $YBa_2Cu_3Ox$ ](YBCO) oxide superconductor was prepared by sol-gel method to improve its superconducting properties, and it was made to be a fine powder, which has the same property of solid state reacted powder. $BaPbO_3$ was synthesized with $BaCO_3$, BaO, PbO, and $PbO_2$ and analyzed by XRD. YBCO superconductor was prepared by use of sol-gelled YBCO powder and additive $BaPbO_3$ and its critical temperature and transition temperature were shown as 91.9 K, 3.7 K respectively in case 20 wt.% $BaPbO_3$ was added to pure sol-gelled YBCO powder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.118-119
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• 2005

PRAM (Phase Change Random Access Memory) is well known to use reversible phase transition between amorphous (high resistance) and crystalline (low resistance) states of chalcogenide thin film by electrical Joule heating. In this paper, we introduce a stack-type PRAM device with a novel GST/TiAlN structures (GST and a heating layer of TiAlN), and report its electrical switching properties. XRD analysis result of GST thin film indicates that the crystallization of the GST film start at about $200^{\circ}C$. Electrical property results such as I-V & R-V show that the phase change switching operation between set and reset states is observed, as various input electrical sources are applied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.213-214
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• 2005

To measure modulus and damping of semiconductive materials in power cable, we have investigated the modulus and damping of semiconductive materials showed by changing the content of carbon black. Then they were produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[$kg/cm^2$]. The content of conduct ive carbon black was the vailable, and their contents were 20, 30 and 40[wt%], respectively. The modulus and $Tan\delta$ experiments were measured by DMA 2980. Ranges of measurement temperature from -50[$^{\circ}C$] to 100[$^{\circ}C$] and measurement frequency is 1[Hz]. The modulus of specimens was increased according to a increment of a carbon black content. And modulus was rapidly decreased at the glass transition temperature. The $Tan\delta$ of specimens was decreased according to a increment of a carbon black content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.280-281
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• 2005

We have studied the superconducting properties and flux pinning enhancement of $(Y_{0.5}Nd_{0.25}Sm_{0.25})_{1.8}Ba_{2.4}Cu_{3.4}O_y$ [(YNS)-1.8] composite oxides by melt growth process in air. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.5}Nd_{0.25}Sm_{0.25})_2BaCuO_5$ [(YNS)211] nonsuperconducting particles were uniformly dispersed in large (YNS)123 superconducting matrix. The sample showed a sharp superconducting transition at 91 K. The magnetization measurements of the (YSN)-1.8 sample exhibited the enhanced flux pinning, compared with $YBa_2Cu_3O_y$ (Y-123) sample without Sm and Nd.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.216-217
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• 2006

A common problem in many fields of cryogenic power engineering is to apply high voltage to cold parts of superconducting equipment. In many of these cases a bushing provides electrical insulation for the conductor which makes the transition from ambient temperature to the cold environment. The cryogenic high voltage bushing for the 154kV, 100MVA high temperature superconducting(HTS) transformer is described. The bushing is energized with the line-to-ground voltage between the coaxial center and outer surrounding conductors, in the axial direction there is a temperature difference from ambient to about 77 K. For the insulation design of cryogenic bushing, the arrangement of condenser cone and electrical insulation characteristics of GFRP, Air, $LN_2$ and $GN_2$ were discussed in this paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.44-45
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• 2006

초고용량 캐패시터(Supercapacitor)는 이차전지와 더불어 차세대 전지로 분류되는 신형에너지 장치로서 충 방전 속도가 다르고 순간 전력공급이 가능하며 충 방전 수명이 반영구적으로 길고 고출력을 내기 때문에 이차전지가 갖지 못하는 영역에서 동력에너지원으로 사용된다. 본 연구에서는 초고용랑 캐패시터의 전극소재인 탄소계 재료를 대신하여 비탄소계 전극소재인 $Li_4Ti_5O_{12}$의 고상법 제조를 위한 Li/Ti의 최적 조성과 혼합 방법으로 Li-Ti 계에 $Fe_2O_3$, NiO, $Nb_2O_5$, $Sb_2O_3$ 그리고 ZnO와 같은 금속산화물로 치환시켜 합성된 Li -Ti계 금속산화물의 특성 및 충 방전 효과에 미치는 영향을 관찰하고자 하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.232-233
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• 2006

In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.