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        검색결과 75

        42.
        2012.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        매연 생성에 대하여 톨루엔의 영향을 알아보기 위하여 순수에틸렌 대향류 확산화염에 톨루엔을 소량 혼합하여 수치해석을 수행하였다. 톨루엔(C7H8)의 혼합 비율은 3%, 5%, 10%, 및 20%로 하였다. 계산에는 CHEMKIN III 기반의 Senkin 코드와 oppdif 코드를 이용하여 0-D 계산과 1-D 계산을 수행하였다. 0-D의 Senkin 계산에서는 톨루엔의 혼합율이 증가할수록 메틸라디칼의 농도는 증가하고 이에 따른 벤젠의 농도도 증가하였다. 이는 순수 에틸렌 화염에 톨루엔을 혼합할 경우 더 많은 매연이 생성될 것이라는 걸 의미한다. oppdif 코드에 의한 1-D 계산에서는 10% 톨루엔 반응식으로부터는 H 라디칼의 생성율이 결정적인 역할을 한다는 것을 알 수 있었다. 위 결과들로부터 확산화염 내 매연 생성에 있어 메틸라디칼, 벤젠과 H 라디칼이 중요한 역할을 한다는 것을 알 수 있었다.
        4,000원
        45.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Experimental measurements of flame shape and heat transfer characteristics were performed for impinged inverse diffusion flame(IDF) using propane as a fuel. The purpose of this study is to identify the favorable co-axial inverse diffusion flame structure for impingement heating. The flame consisted of an entrainment zone and mixing and combustion zone. The heat flux which represents heat transfer rate is measured by using a heat flux sensor that is located at the center of the impingement plate. The inverse diffusion flame structure has been classified into six modes. In these modes, several favorable flames for impingement heating were identified. In this study, the parameters are overall equivalent ratio(Φ), nozzle to impingement plate distance(h/d), vertical distance from the stagnation point and Reynolds number(Re) of combustion air.
        4,000원
        46.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Various inorganic fillers improve the thermal conductivity and physical properties of organic products. Alumina has been used a representative filler in the heat radiation sheet for the heat radiation of electric device. The high filling rate of alumina increases the thermal conductivity and properties of products. We successfully developed the spherical alumina by flame fusion process using the oxygen burner with LPG fuel. In the high temperature flame (25003000) of oxygen burner, sprayed powders were melting and then rotated by carrier gas. This surface melting and rotation process made spherical alumina. Especially effects of chemical composition and particle size of stating materials on the melting behavior of starting materials in the flame and spheroidization ratio were investigated. As a result, spheroidization ratio of boehmite and aluminum hydroxide with endothermic reaction of dehydration process was lower than that of the sintered alumina without dehydration reaction.
        4,000원
        47.
        2008.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Green-emitting Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders under long-wavelength ultraviolet light were prepared via high-temperature flame spray pyrolysis from spray solutions with and without NH4Cl flux. The effects of the temperature of the diffusion flame and the NH4Cl flux on the morphologies, crystal structures and photoluminescence intensities of the Ba1.468Sr0.5SiO4 : Eu0.012, Y0.02 phosphor powders were investigated. The phosphor powders obtained from the spray solution with the NH4Cl flux had higher photoluminescence intensities compared to phosphor powders obtained from the spray solution without the flux. The photoluminescence intensity of the phosphor powders obtained from the spray solution without the flux decreased as the flow rate of the fuel gas increased. On the other hand, the photoluminescence intensity of the phosphor powders obtained from the spray solution with the flux increased as the flow rate of the fuel gas increased. The difference of in the phase purity and morphology of the powders affected the photoluminescence intensities of the phosphor powders.
        4,000원
        49.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanopowders of titanium dioxide incorporating the transition metal element(s) were synthesized by flame synthesis method. Single element among Fe(III), Cr(III), and Zn(II) was doped into the interior of crystal; bimetal doping of Fe and Zn was also made. The characteristics of transition-metal-doped nanopowders in the particle feature, crystallography and electronic structures were determined with various analytical tools. The chemical bond of Fe-O-Zn was confirmed to exist in the bimetal-doped nanopowders incorporating Fe-Zn. The transition element incorporated in the was attributed to affect both Ti 3d orbital and O 2p orbital by NEXAFS measurement. The bimetal-doped nanopowder showed light absorption over more wide wavelength range than the single-doped nanopowders
        4,000원
        51.
        2004.11 구독 인증기관 무료, 개인회원 유료
        It compared quality characteristics for the stone surface treatment system and its products. With the result, the flame burner equipment was mainly used to the surface treatment of granite, but it occurred greatly the high temperature, the rock fragment, the noise and dust. For the other side, the whetstone polishing machine for the polishing was a maintenance for the specific physical properties of stone, and it did not occur the stone fragment and the dust. The durability of the stone products due to the flame burner was investigated with that it falls to 20~25% more than the surface treatment by the whetstone polishing. Share's hardness of the polishing products in the durability test showed more greatly index than the flame burner and conventional product. The polishing products of Pochon stone in the case of the abrasion resistance showed great more 15% than the general products, more 9% than the products by the flame burner.
        4,000원
        53.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        nanopowder has been synthesized by means of the flame method using a precursor of titanium tetraisopropoxide (TTIP, Ti. In order to clarify the effect of cooling rate of hot flame on the formation of crystalline phases, the flame was controlled by varying the mixing ratio and the flow rate of gases. Anatase phase was predominantly synthesized under the condition having the steep cooling gradient in flame, while a slow cooling gradient enabled to form almost rutile nanopowder of above 95%
        4,000원
        54.
        2003.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To comparison the surface treatment methods of stone board materials, the results of Dorry's abrasive test were 23.4 for water-jet system and 18.9 for flame-burner system. Therefore abrasive hardness, the stone board materials by the water-jet system was greater than one by flame-jet system. As a result of Shore's hardness test, the stone board materials by water-jet system was twice greater than one by flame-jet system. Authors carried out microscopic observation to survey a defection of the composition minerals for two methods, but all of the both methods have not founded a defection. Therefore, the stone board materials by water-jet system was greater durability than one by flame-jet for the surface treatment methods.
        4,600원
        59.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The formation of powder by oxidation of Ti-ethoxied vapor in a flat flame burner reactor maintained under 20 torr has been studied. The produced powder were characterized in terms of crystal structure, chemical composition by XRD and TEM. The results showed that the powder consisted of loose agglomerated anatase and rutile particles and their size were about 10 nm and 20 nm, respectively. In the course of synthesis, changes of the flame color were happened to each condition during heating up the bubbler. The flame color transition phenomena reveled that a critical precursor delivery rate was needed for the powder formation (obtainable powder yield). The critical precursor delivery rate was estimated by a simple function of the bubbler temperature and the carrier gas flow rate. The critical precursor delivery rate was reviewed as an important variable of the nanopowder synthesis.
        4,000원
        60.
        1996.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        연소화염법을 이용한 다이아몬드 박막합성은 기판의 표면상태에 크게 의존한다. 특히 탄소결합상이 기판에 조재하는 경우 다이아몬드 핵생성과 성장은 크게 영향을 받는다. 본 연구에서는 일정한 흡입가스비율(R=O2/C2H2)과 기판온도 조건의 연소화염법을 이용하여 몰리브덴 기판위에 다리아몬드박막을 합성하는 과정에서 박막의 핵생성에 미치는 기판 탄소화합물의 영향을 조사하였다. Mb 금속기판표면에 형성된 탄화물로는 Mo2C상과 soot를 택하여 박막합성 전에 Mo기판상에 형성시켰다. Mo 금속기판표면에 형성된 탄화물(Mo2C)상에는 다이아몬드 핵생성과 입자성장이 촉진되어 가장 조대한 양질의 다이아몬드 입자가 형성되었다. 이것은 탄화물상이 반응가스중의 탄소의 확산을 저지함과 동시에 핵생성의 필요한 잠복기간을 감소키켰기 때문이다. 그러나 soot를 구성하는 미세한 탄소결합상들이 다이아몬드 핵생성 장소로 작용하여 결과적으로 다이아몬드 수밀도가 가장 크게 관찰된 반면, 입자성장은 Mo2C기판에 비해 작았다.
        4,000원
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