• 제목/요약/키워드: ultra-flowing

검색결과 27건 처리시간 0.041초

분무건조법에 의해 제조된 Ti-Co-O계 산화물 분말의 고체 탄소에 의한 환원/침탄 (Carbothermal Reduction of Spray Dried Titanium-Cobalt-Oxygen Based Oxide Powder by Solid Carbon)

  • 이길근;문창민;김병기
    • 한국분말재료학회지
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    • 제11권1호
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    • pp.28-33
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    • 2004
  • In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of $TiO_2$ and $CoTiO_3$. This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of $CoTiO_3$ to $TiO_2$ and Co, reduction of $TiO_2$, to the magneli phase($Ti_nO_{2n-1}$, n>3), reduction of the mag-neli phase($Ti_nO_{2n-1}$, n>3) to the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases, and reduction and carburization of the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases to titanium carbide.

철심의 히스테리시스 특성을 고려한 CCVT 2차 전압 보상방법 (Compensating algorithm of the secondary voltage for CCVT considering the hysteresis of a iron core)

  • 강용철;이병은;정태영;이지훈;김연희;박종민;소순홍;장성일
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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    • pp.261-263
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    • 2005
  • In the extra and ultra high voltage system, the coupling capacitor voltage transformer (CCVT) measures the primary voltage with a small scale of voltage transformer (VT). However, the CCVT generates errors caused by the hysteresis characteristics of iron core and by the ferroresonance, inevitably. This paper proposes a compensation algorithm for the secondary voltage of a CCVT considering the hysteresis characteristics of an iron core. The proposed algorithm calculates the seconda교 current of a VT by summing the current flowing the ferroresonance circuit and the burden current; it estimates the secondary voltage of a VT; then the core flux is calculated by integrating of the secondary voltage of a VT, then estimates the exciting current using ${\lambda}-i$ characteristic of the core. The method calculates a primary voltage of a VT considering the estimated primary current. Finally, the correct voltage is estimated by compensating the voltage across the inductor and capacitor. The performance of the proposed algorithm was tested in a 345kV transmission system. The test results show that the proposed method can improve the accuracy of the seconda교 voltage of a CCVT.

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통신용 부품제작을 위한 유기초박막의 전자특성에 관한 연구 (Photo Displacement Properties of Nano structure Organic Ultra Thin Films)

  • 송진원;조수영;김영근;김형곤;이경섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 추계학술대회 논문집
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    • pp.27-32
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    • 2004
  • Maxwell displacement current (MDC) measurement has been employed to study the dielectric property of Langmuir-films. MDC flowing across monolayers is analyzed using a rod-like molecular model. A method for determining the dielectric relaxation time ${\tau}$ of floating 'monolayers on the water surface is presented. MDC floing across monolayers is analyzed using a rod-like molecular model. It is revealed that the dielectric relaxation time ${\tau}$ of monolayers in the isotropic polar orientational phase is determined using a liner relationship between the monolayer compression speed a and the molecular area Am. Compression speed a was about 30,40,50mm/min. LB layers of Arachidic acid deposited by LB method were deposited onto slide glass as Y-type film.The physicochemical properties of the LB films were examined by UV absorption spectrum, SEM and AFM. The structure of manufactured device is Au/Arachidic acid/Al, the number of accumulated layers are 3~9. Also, we then examined of the MIM device by means of I-V characteristic of the device is measured from -3 to +3[V]. The insulation property of a thin film is better as the distance between electrodes is larger.

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분무건조법에 의해 제조된 Ti-Co-O계 산화물 분말의 환원/침탄반응에 미치는 코발트 산화물의 영향 (Effect of Cobalt Oxide on Carbothermal Reduction of Spray Dried Titanium-Cobalt-Oxygen Based Oxide Powder)

  • 이길근;김찬영
    • 한국분말재료학회지
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    • 제12권5호
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    • pp.336-344
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    • 2005
  • In the present study, the focus is on the effect of cobalt oxide powder in the carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fine TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under flowing argon atmosphere. Changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. Titanium-cobalt-oxygen based oxide powder desalted at $600^{\circ}C$ had a mixture of $TiO_2\;and\;Co_{3}O_4$. And the one desalted at $800^{\circ}C$ had a mixture of $TiO_2\;and\;CoTiO_3$. In the case of the former powder, the reduction of cobalt oxide powder in the titanium-cobalt-oxygen based oxide powder occurred at lower temperature than the latter one. However, the carbothermal reduction of titanium dioxide powder in the titanium-cobalt-oxygen based oxide powder with a mixture of $TiO_2\;and\;Co_{3}O_4$ occurred at higher temperature than the one with a mixture of $TiO_2\;and\;CoTiO_3$. And also, the former powder showed a lower TiC formation ability than the latter one.

Electrical Characterization of Nanoscale $Au/TiO_2$ Schottky Diodes Probed with Conductive Atomic Force Microscopy

  • Lee, Hyunsoo;Van, Trong Nghia;Park, Jeong Young
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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    • pp.290.1-290.1
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    • 2013
  • The electrical characterization of Au islands on TiO2 at nanometer scale (as a Schottky nanodiode) has been studied with conductive atomic force microscopy in ultra-high vacuum. The diverse sizes of the Au islands were formed by using self-assembled patterns on n-type TiO2 semiconductor film using the Langmuir-Blodgett process. Local conductance images showing the current flowing through the TiN coated AFM probe to the surface of the Au islands on TiO2 was simultaneously obtained with topography, while a positive sample bias is applied. The boundary of the Au islands revealed a higher current flow than that of the inner Au islands in current AFM images, with the forward bias presumably due to the surface plasmon resonance. The nanoscale Schottky barrier height of the Au/TiO2 Schottky nanodiode was obtained by fitting the I-V curve to the thermionic emission equation. The local resistance of the Au/TiO2 nanodiode appeared to be higher at the larger Au islands than at the smaller islands. The results suggest that conductive atomic force microscopy can be used to reveal the I-V characterization of metal size dependence and the electrical effects of surface plasmon on a metal-semiconductor Schottky diode at nanometer scale.

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R을 이용한 서울시 교통량과 미세먼지 발생의 상관관계 분석 (Relationship Analysis between Fine Dust and Traffic in Seoul using R)

  • 황승연;문진용;김정준
    • 한국인터넷방송통신학회논문지
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    • 제19권4호
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    • pp.139-149
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    • 2019
  • 2018년 현재, 중국에서는 편서풍을 타고 다량의 미세먼지가 한국으로 유입되고 있다. 하지만 국내에서 발생되는 미세먼지양도 무시할 수 없다. 심지어 미세먼지 발생원인의 52%가 국내요인이다. 특히 인구가 밀집된 서울에서는 다른 지역과 비교할 수 없을 만큼 미세먼지 수치가 높다. 서울시에서도 구별로 미세먼지 수치는 다르게 나타난다. 구별로 미세먼지의 발생 차이를 이해하기 위해 서울시 미세먼지 발생원인 중 가장 높은 교통량을 기준으로 판단한다. 2017년의 교통량과 미세먼지의 농도를 비교해 실제로 교통량이 영향을 미치는지, 얼마나 영향을 미치는지, 만약 영향을 주지 않는다면 그 원인은 무엇인지 R을 이용해 비교해보고 서울시 미세먼지 발생의 원인을 확실히 인식한다.

유영국(劉永國)의 초기 구성주의: <랩소디>(1937)에 나타난 유토피아니즘 (Yoo Young-kuk's Early Constructivism: Utopianism in (1937))

  • 유영아
    • 미술이론과 현장
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    • 제9호
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    • pp.93-121
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    • 2010
  • This study is about Yoo Young-kuk's early works which show constructivism, especially focus on his debut painting, for the 7th Dokuritsu Bijutsu Kyokai(獨立美術協會, the Independent Fine Arts Association) in Tokyo in 1937. The work was painted 2 years after he had started his study in Japan in 1935. It was the first painting that applied Constructivism. played an important role for Constructivism to be a leading art in his abstraction. After this picture, Yoo was soon devoted to the principles of Constructivism-- Faktura(material), Tektonika (tectonics), Tekhnika(technique), space, construction-- in his painterly reliefs. This article examined why Yoo concentrated on Constructivism for , what the characteristics were, and what influences were on other works from 1935 to 1949. In addition, I investigated in which period was painted and how Constructivism was spread in 1930s and early 1940s in chapter 2. I scrutinized Rhapsody in chapter 3. When Yoo created Japan was under the Fifteen Years War(1931-1945), and a major discourse was the Japanese Spirit at that time. It was connected with construction of an ideal nation which the Japanese ultra-national fascism pursued. This ideological pursuit was intended to unite the Japanese people for total war system and to restore a national dignity which had been fallen down due to Manchurian Incident(1931). Thus, on the hand, Kokusai Bunka Shinkokai(國際文化振興, The Society for International Cultural Relations) and the Nippon Kosaku Bunka Renmei(日本工作文化連盟, Japanese Werkbund) were supported financially by the Japanese government. On the other hand, the government enacted regulations to opposing parties which would distract Japanese people's unification. As for the Japanese art world, the merge of art groups was carried out through remodeling of Teikoku Bijutsuin(帝國美術院, The Imperial Fine Arts Academy) in 1935. This brought out continuous dispute and disorder. Young artists who felt difficulty of entering an entry of Imperial Fine Arts Exhibition repeatedly grouped and disbanded for small art groups to build their standing, which they pursued Surrealism and Abstract art. Among them Constructivism was considered as the latest trend and was popular in craft, design, architecture as well as fine arts. In the year before he painted , Avant-garde theatres including Constructivism theatre were introduced in a feature article of September, 1936 in Atelier, which was dealing with mainly avant-garde arts. Books related with Constructivism were translated into Japanese, and Gestaltung Education had become active since the publication of A Compendium of Gestaltung Education("構成敎育大系"(1934)), Salvador Dali(1904-1989) was also introduced, so Surrealism was drawn more attention by young artists. reflected popular trends. Yoo analyzed the Japanese avant-gardists' archaic taste in the Independent Art Association that he submitted his painting to. And then he entitled 'Rhapsody' which derives from Ancient Greek's epic poetry and deliberately set up images in a scene. In chapter 3, I examined a theme which was planned carefully by sorting favorite images from the Japanese Surrealism. was a result that Yoo Young-kuk observed objectively the phenomenon that young artists dreamt of Utopia or longed for Nostalgia passively and lethargically under wars. And then he otherized himself from that circumstance. First of all, for he used the typical icons of Japanese Surrealism such as the horizon, flowing clouds, and vast plain that were considered stereotypes of Arcadia. He, however distinguished himself form those Japanese Surrealists. He made his own vision about Utopia by referring Lyubov Popova(1889-1924)'s stage design. His objective point of view was expressed by positive and dynamic images of structure and human's actions. Constructivism which was attempted in had an effect on other early constructive works, and the principles of Constructivism were sought hard in reliefs, paintings, and photos.

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