SHS 화학로에 의한 $B_4C$ 합성 및 기계적 특성에 관한 연구

이형복,조덕호,박성,이재원,Lee, Hyung-Bock,Cho, Duk-Ho,Park, Sung,Le, Jea-Won 한국세라믹학회 1993 한국세라믹학회지 Vol.30 No.8

Boron cabride was prepared from the mixture of metal boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis Chemical furnace. The most excellent mechanical properties were in the case that Fe was added as a sintering agent before the synthesis of the B4C in the Chemical furnace. Sintered B4C-5wt% Fe specimen showed the relative density of 95%, of theoretical value, and 3-point-flexural strength of 380MPa.

상압소결에 의하여 제조된 SiC-AlN 세라믹스의 상 및 미세구조

최웅,이종국,조덕호,김환,Choi, Woong,Lee, Jong-Kook,Cho, Duk-Ho,Kim, Hwan 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.11

Changes in phase and microstructure were investigated in the SiC-AlN ceramics prepared by pressureless sintering using yttrium aluminum garnet (YAG) as a sintering aid at 200$0^{\circ}C$ and 210$0^{\circ}C$. The SiC/AlN ratio made a remarkable difference in densification, phase relations and the morphology of grains. In the AlN-rich composition, major phase was 2H and microstructure was composed of the densified equiaxed grains irrespective of the sintering temperatures. While those sintered at 200$0^{\circ}C$ were porous with major phase being 3C, the rod-like and the equiaxed grains were coexisted when sintered at 210$0^{\circ}C$ in the SiC-rich composition.

SHS법에 의한 Ti-Si계 세라믹스의 합성 및 소결체의 특성에 관한 연구

김도경,박성,조덕호,조건,이형복,Kim, Do-Kyung,Park, Sung,Cho, Duk-Ho,Cho, Kurn,Lee, Hyung-Bock 한국세라믹학회 1994 한국세라믹학회지 Vol.31 No.3

Intermetallic Ti-Si system ceramics were synthesized from stochiometric mixtures of titanium and silicone powders in vacuum by Self-propagating High-temperature Synthesis(SHS). In each cases of Ti5Si3, Ti5Si4 and TiSi, and TiSi2 synthesis, 20wt% product dilution, direct ignition and SHS chemical furnace method were employed. The combustion modes, which were observed during the synthesis process by using the high speed camera, of Ti5Si3, Ti5Si4, TiSi, and TiSi2 exhibit spin, osciallatory, steady-state, and spin combustion, respectively. With increasing Ti/Si molar ratio an decrease of combustion velocities was found. From the results on the measurement of the flexural strength, the specimen hot pressed at 135$0^{\circ}C$ for 30 min using synthesized Ti5Si4 powders showed the highest flexural strength at 215 MPa.

이산화티탄이 코팅된 알루미나 볼에서 광촉매 반응에 의한 기상벤젠의 분해

이남희,정상철,선일식,조덕호,신승한,김선재,Lee Nam-Hee,Jung Sang-Chul,Sun Il-Sik,Cho Duk-Ho,Shin Seung-han,Kim Sun-Jae 한국재료학회 2004 한국재료학회지 Vol.14 No.6

Photo decomposition of gas phase benzene by $TiO_2$ thin films chemically deposited on alumina balls were investigated under UV irradiation. Photo decomposition rates were measured in real time during the reaction using a photo ionization detector, which ionizes C-H bonding of benzene molecules and then converts into volatile organic compounds (VOCs) concentrations. From the measuring results, the VOCs concentration increased instantly when IN irradiated because C-H bonds of benzene molecules strongly absorbed on the surface of $TiO_2$ films before the IN irradiation was destroyed by photo decomposition. After that, the VOCs concentration decreased with increasing surface area of $TiO_2$ and reaction time under the IN irradiation. At the optimal conditions for the photo decomposition of gas phase benzene, the reaction rate of the photo decomposition for high concentrations (over 60 ppm) was slow but that of relatively low concentration (under 60 ppm) was fast, due to limited surface area of $TiO_2$ thin films for the reaction. Thus, it is concluded that the photo decomposition rate was mainly affected by the surface area of $TiO_2$ or absorption reaction.

라이덴(Leyden) 기법 적용을 통한 농촌노인 가구의 최저생계비 측정

정영숙(Young Sook Chung),조덕호(Duk Ho Cho) 한국노인복지학회 2009 노인복지연구 Vol.0 No.46

농지연금모형 적용을 통한 적정생계비 추정과 농촌노인복지 실현방안

정영숙(Young Sook Chung),조덕호(Duk Ho Cho) 한국노인복지학회 2009 노인복지연구 Vol.0 No.44

광섬유를 이용한 광촉매 성능 측정 표준화의 이해

주현규(Joo Hyun-Ku),하진욱(Ha Jin-Wook),조덕호(Cho Duk-Ho) 한국산학기술학회 2005 한국산학기술학회논문지 Vol.6 No.4

최근 일본이 광촉매 관련 제품에서의 소비자 보호를 위한 적절한 표준화 규격 제정에 강한 의욕을 보이며, 자국내 JIS 규격 외에 ISO 규격 (ISO/TC 206 fine ceramics)을 제정하기 위하여 노력하고 있다. 이에 국내에서는 산업 보호 및 해외시장에서의 종속성을 벗어나기 위하여 2001년부터 선정된 분야에서의 광촉매표준화 시도가 이루어졌다. 그 중의 하나로 본 논문은 광섬유를 빛전달 매개체와 광촉매 코팅 지지체로 이용해서 광촉매 졸을 구성하는 광촉매 자체의 유기물 분해능을 결정하는 방법을 규정하는 과정과 제안과 관련된 것이다. 이 규격은 코팅 가능한 졸이나 졸로 만들 수 있는 자외선 감응 광촉매 재료에 적용하며, 차후 가시광 및 태양광 감응 광촉매 활성 측정 및 비교에도 응용이 가능할 것으로 판단된다. Recently, Japan has showed strong demand for protection of consumers against misleading specification provided by producers, establishing the committee for 1IS and ISO. To protect domestic market and overcome potential subordinate relationship in overseas market, several universities and institutes in Korea have performed collaborative works on the standardization of test method for photocatalytic activity concerning the selected application fields. This article deals with the process and the result for the method of testing photocatalytic sol or suspended powder using optical fiber. Currently, this method is intended for TiO₂, but can be applied for various photocatalytic raw materials that can be activated by visible light and solar irradiation.

MnZn ferrite 의 물리적 성질에 미치는 하소조건의 영향(1)

조덕호 大田産業大學校 1995 한밭대학교 논문집 Vol.12 No.0202

In this study, preparing the specimens of MnZn ferrites with the chemical composition of zero magnetostriction and zero magnetic anisotropy, we investigated the effects of the calcining conditions on the microstructure and physical properties of MnZn ferrites. The results obtained from these experiments are as follows: As the calcining temperature increases, the content of spinel phase formed during calcining process increases linearly and the average particle size milled after calcining increases. Since it is suitable for the calcined ferrites to get the spinel phase about 70% and the average particle milled after calcining to be below 2㎛ in order that sintering of ferrites may be promoted in the subsequent sintering process, the optimum calcining temperature obtained in this study is 900℃ for 2 hours. The specimen not calcined shows volume expansion between 600~700℃ during sintering process and has the shrinkage rate greater than the calcined specimen.

역저당연금제도를 위한 부동산가격의 장기 예측방법

마승렬,조덕호 한국보험학회 2003 保險學會誌 Vol.66 No.-

본 연구는 한국이 주택금융시장에서 노인의 주거 및 생활안정을 보장할 수 있는 새로운 주택금융 형태인 역저당연금제도를 정립하기 위해 동제도의 필수 요소인 부동산가격의 장기 예측모형의 설정에 중점을 두고 있다. 과거의 시계열자료를 사용하여 미래 특정시점의 부동산가격의 현가를 산정하기 위해서는 과거의 시계열 추이가 미래에도 동일하거나 또는 거의 유사한 추이를 따를 것이라는 믿음을 주어야 한다. 본 연구의 분석결과에 의하면 부동산가격의 순할인비율 시계열이 안정적 시계열로 확인되었다. 따라서 우리는 이들 시계열의 역사적 평균값만을 사용하더라도 장기적인 미래 주택가격의 시계열 추이를 합리적으로 예측할 수 있음을 확인할 수 있었다. 이를 바탕으로 본 연구는 미래의 부동산 가격과 수익률시계열에 대한 장기 예측문제의 어려움을 제거하면서 순할인비율 시계열자료의 역사적 평균값만을 이용하여 미래 부동산 가격을 예측하는 단순화된 예측모형을 설정하였다. This study focuses on the building of long term forecasting model of real estate price for establishing the reverse annuity mortgage which aims the residental and living stabilization for the elderly household in the Korean housing market. In order to measure the present value of real estate price in the future certain time using the past time series data, this time series trend should be same or similar in the future time. The result of this study shows that the time series of net discount ratio is stationary, and then we can confidentially forecast the trend of time series of future real estate price through using the historical average value of past time series data. Based upon this analysis output, this paper builds the forecasting model of future real estate price eliminating the difficulty of long term forecasting problems of future time series.

α-Sialon 세라믹스(X=0.15)의 기계적 성질에 미치는 소결분위기 및 ZrO₂의 첨가 영향

임헌진,조덕호,이홍림,이경원 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.1

4.82 wt% AIN and 2.95 wt% Y₂O₃were added to Si₃N₄as sintering agents in order to have α-Sialon composition of X=0.15 and monoclinic ZrO₂between 0 to 10 wt% was admixed with Si₃N₄. Si₃N₄based ceramics were fabricated by hot-pressing at 1750℃ for 90 min under 30 MPa in argon and nitrogen atmospheres Effects of sintering atmospheres and addition of ZrO₂on mechanical proporties of Si₃N₄based ceramics were investigated. As ZrO₂content increased, the fraction of α-Sialon tended to decrease and the amount of cubic ZrO₂increased because Y₂O₃acted as the stabilizer of ZrO₂. The sintering atmospheres didn't affect on the sintering behavior and the product phases in hot-pressing of Si₃N₄. Bending strength increased when ZrO₂was added up to 3 wt%. Hardness showed tendency to decrease with ZrO₂content. ZrO₂didn't contribute to the increase of fracture toughness because stabilized cubic ZrO₂was produced by the added Y₂O₃.