(Ba·Pb)TiO₃세라믹 반도체의 큐리점 이동에 관한 연구

소대화,강기성 明知大學校 産業技術硏究所 1988 産業技術硏究所論文集 Vol.7 No.-

When Sb₂O₃as a dopant is added into commerical BaTiO₃and BaTiO₃made by solid Synthesis with 3aCO₃and TiO₂, the electrical conduction is increased in more efficient way. The addition of PbTiO₃ to BaTiO₃ by 10 mole %, 20 mole %, 40 mole % respectively cause tile curie points to occurs at higher temperature than that of pure BaTiO₃(Tc= 120℃). In case of PbTiO₃additions, the curie point shows about 4℃ increase by 1 mole%. In accordance with the mole ratio of PbTiO₃, the condition of sintering temperature for the specimens of (Ba.Pb) TiO₃was also changed ; when the ratio of PbTiO₃ was increased, the optimal sintering temperature was lowered.

첨가물에 따른 고온 초전도 후막의 특성

소대화,전용우,이영매,김태완,Korobova, Natalya 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

In this study, by using the electrophoresis, preparation of YBCO superconducting wire deposited on metal Ag base wire was studied with its properties. YBCO powder could be prepared by solid state reactions with calcining and sintering processes. Superconducting wire prepared on metal Ag wire used as cathode of deposition base could be also fabricated in the YBCO/acetone-dispersed solution to obtain several tens of ㎛ thick films. In the process of film deposition, a catalyst I₂added into the suspension solution was very useful for preparing thick film of YBCO, and BaF₂ of additive material was also necessary for preparing crack-free wire of YBCO superconductor. As a result, YBCO superconducting wire added 2~3wt.% of BaF₂with catalyst, I₂had better deposition condition for uniform and dense YBCO wires, and critical current density, Jc was calculated at the value of 1,458A/㎠ (more than 10³A/㎠, 77K, 0[T]) of 30㎛ thick sample by 4-point prove method.

CDI 點火裝置의 進角特性에 關한 考察

蘇大和 명지대학교 1983 明大論文集 Vol.14 No.-

The characteristics of the ignition time with respect to the engine speed(r.p.m) was studied in theoritically to the conventional capacitor discharge ignition(C.D.I.) system which is used in the small gasoline engines. In this system, we found that the advanced angle of the ignition time decreased when the engine speed was increased because of the circuit reactance. It is very disadvantageous for the engine efficiency and it decreases the engine power by increasing the operation speed. In this study, we will discuss the disadvantages of the above, and propose the desirable circuit and design methods of the C.D.I. system for small 2 stroke gasoline engines.

관광동굴의 친환경 조명과 녹색 전원 장치

소대화 明知大學校 産業技術硏究所 2009 産業技術硏究所論文集 Vol.28 No.-

In the cave, there are able to exist CO₂ gas and H₂O humidity from the human breathing and in atmosphere or the underground water, and also the light can be irradiated by the illumination fixtures for tourism and caving. For this reason, the green plants of moss and others could be created and grown on the rock in the cave by the photosynthesis reaction, however, sometimes there would be the dry season to be killed the green mosses and plants, and hence , it could be dried and blackish‘ When the dried mosses were taken off from the surface of the rock like as laminated dried one, the moss lamination could be taken off together with the skin of the formated stalactite in the cave‘ Therefore, the cave environment should be changed and degenerated unfortunately, though it is undesirable‘ So it is necessary to control the cave environment to be better condition somehow by using suitable methods such as selective wave lighting irradiation to make photosvnthesis or not to make it in there bv the lighting fixtures of LED lamps.

현탁용매에 따른 전기영동 초전도 후막의 영향

소대화,박정철,이영매,조용준,Korobova, Natalya 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

For the research of the effects on suspension solution with YBcO and BSCCO for elcectrophoretic deposition to prepare superconducting thick film wire, the preheating technique for the superconducting powders in vaccum system was used with various solvent solutions for electrophoresis such as acetone, toluen and buthanol was investigated. As a result, it was useful to remove the influence of remaining and adsorbed solvent solution which was existed between and on the particle surfaces when the specimens of superconducting wire by electrophoresis were treated in vacuum of 10-3 Torr and temperature around 200℃ in bell-jar system. Of the prepared superconducting wire samples, the critical current density, Jc was measured by 4-point prove method in liquid N₂, and at the value of 10³to 10⁴A/㎠, respectively, for the YBCO and BSCCO superconducting wires.

보조전계 BSCCO 전기영동 전착막의 현탁용매 영향 : Influences of Suspension Solution on Field-assisted EPD Films of BSCCO

소대화,전용우,박정철 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - In the electrophoresis for fabrication of a superconducting wire and film, the enough deposition and formal sustain of a film condition affect to superconducting state of samples. In this paper, a superconducting film was fabricated with various suspension solution such as acetone, buthanol, and ethanol. As a results, the best deposition condition with d.c 250 V and a.c 25 V of applied voltage, and 90 sec of applied time for BSCCO superconducting film by electrophoresis was investigated.

IMO의 선박안정수 규제와 외래침입생물체의 전기화학적 처리기술

소대화,전용우 明知大學校 産業技術硏究所 2005 産業技術硏究所論文集 Vol.24 No.-

The introduction of invasive marine species into new environments by ship's ballast water, attached to ships' hulls and via other vectors has been identified as one of the four greatest threats to the world's oceans by Global Environment Facility (GEF). IMO (International Maritime Organization) is carrying out the international restriction of the effluence suppression and treatment of Ship's ballast water by Ballast Water Management Convention. In this paper, to deal with this international restriction convention and to consider economic potential of ship's ballaster treatment market near future, the equipment and technology of ship's ballaster water treatment was studied.

MTG법에 의한 YBCO 고온 초전도체의 특성 연구

소대화,반점국 明知大學校 産業技術硏究所 1994 産業技術硏究所論文集 Vol.13 No.-

In this paper, by means of adding nonsuperconductive phase silver into YBCO matrix, the superconductivity of Melted Texture Growth(MTG) YBaCuO was improved remarkably. In order to eliminate the crack in the YBCO and the weak link in the grain boundary, Ag contents from 2wt% to 18wt% were doped in the YBCO. It was found that Jc of YBCO increases with the increasing Ag content till 14wt%, over 14wt% of Ag contenr, the Jc tends to stable. The grain size of YBCO became fine when Ag was added in the YBCO and X-ray diffraction showed that the YBCO crystal prepared by the above technique had (001) oriention and growing plane of YBCO was a-b plane. Using Bean´s medel, the Jc was calculated and the best result was Jc = 76000 A/cm²(77K, 100Gs).

전기영동 초전도후막의 전착밀도 개선

소대화,전용우,이영매,임병제,Korobova, Natalya 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

YBCO superconducting thick films were perpared on Ag wire by electrophoresis in acetone and ethanol with chemically modified suspension. The addition of organic compounds, such a PEG into suspension solution for improving critical current density was investigated. Surfac state, deposition conditions, pore distribution and cracks were investigated by using SEM photographs. Controlling preparation conditions were studied for reducing these defects. As a results, in acetone slolution, the surface crack of samples was decreased with increasing PEG. To develop optimum microstructures for samples processes affect the microstructure and hence the properties of ceramic superconductors.

MCP법에 의한 YbBaCuO 초전도체 제조연구

이영매,소대화 명지대학교 대학원 1997 대학원논문집 Vol.1 No.-

In this paper, YbBa_2Cu_3O_x superconductor was sinterd by means of conventional solid reaction and the textured YbBa_2Cu_3O_x was prepared by the Melted-condenced process in which SmBa_2Cu_3O_x crystal was used as seed crystal to introduce the YbBa_2Cu_3O_x crystal growth. The texture of YbBa_2Cu_3O_x was examined by X-ray diffraction, and the fracture of YbBa_2Cu_3O_x sample was observed by SEM, which proved the sample was well oriented. After oxygen absorption of the textured YbBa_2Cu_3O_x sample, the critical temperature was measureed to be 86k. The critical current density was obtained at the value of 770A/㎠(77K, OH) calculated by Bean's Model using the measured values of hysterisys curve of VSM.