• 제목/요약/키워드: 김영기

검색결과 943건 처리시간 0.024초

상호확산법에 의한 (Ti,Al)N계 복합질화물의 합성 (Synthesis of (Ti,Al)N Powder by Interdiffusion Nitriding Method)

  • 이영기;김정열;김동건;손용운
    • 열처리공학회지
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    • 제10권2호
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    • pp.138-149
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    • 1997
  • TiN and AlN are ceramic materials with extensive applications due to its excellent mechanical and chemical properties at elevated temperature. The purpose of this research is to develop the method for the synthesis of ternary nitride powder, titanium-aluminum-nitrogen system, which have an excellent property of both TiN and AlN. The ternary nitride such as $Ti_3AlN$, $Ti_2AlN$ and $Ti_3Al_2N_2$ can be synthesized by the interdiffusion nitriding method in Ar gas, however, the ternary nitride coexist with TiN, AlN, $Ti_3Al$ and ${\alpha}$-Ti. The ternary nitride are stable below $1400^{\circ}C$, but these are gradually decomposed into TiN, $Ti_3Al$ and AlN above $1400^{\circ}C$. The thermal oxidation characteristics of the Ti-Al-N compound synthesized by the interdiffusion nitriding method is superior to that of the TiN+AlN mixed powder, and the oxidation for both materials show the differential behaviors.

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자돈 축추골 몸통의 골화에 관한 조직학적 연구 (The histological study on ossification of the body of the piglet axis)

  • 안동춘;김인식;양홍현;백영기
    • 대한수의학회지
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    • 제35권1호
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    • pp.19-28
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    • 1995
  • The histological and histochemical study of the axis body of piglet was performed in order to clarify the ossification process. These experimental animals collected from after birth to 52 days were used for this study. The results were summarized as follows; 1. The epiphysis, the intercentrum 2 and the centrum of proatlas were appeared in the axis body and dens of piglet after birth. 2. In 39 days of age piglet, the ossification of the intercentrum 2 was first observed but the epiphysis was already initiated. The centrum of proatlas was observed cranioventral part of the dens of the 52 days piglet axis. 3. The notochordal remnants revealed distinctively in the part between the centrum 1 and the centrum2, in the apical cartilaginous tissue of dens and in the caudal cartilaginous part of body of axis. 4. Intramembranous ossification occurred in the adjacent area of perichondrium of centrum 2. These ossified trabeculae show the woven bone configuration.

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멸치액젓 중 혈전용해효소의 경구 투여 효과 (Effect of Oral Administration of Fibrinolytic Enzyme from a Fermented Anchovy, Myulchi Jeot-Gal)

  • 정영기;양웅석;김병기
    • 생명과학회지
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    • 제8권6호
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    • pp.737-740
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    • 1998
  • 멸치액젓으로부터 분리한 혈전용해효소를 rat에 경구투여하여 혈액내에서 효소활성을 확인 하였다. 경구투여 후 0, 1, 2, 3, 4시간 후에 혈액을 채취하여 fibrin분해활성을 본 결과 1시간부터 활성이 나타나기시작하여 3시간째에 가장 높았다. Euglobulin Iysis time(ELT)도 경구투여 2, 3시간후에 활성을 보였다. 또한, euglobulin에 의한 amidolysis acti-vity도 1시간부터 활성이 보이기 시작하여 3시간후에 최고활성에 달했다. 이상의 결과로 동물실험을 통한 혈전용해효소의 경구투여에 의한 활성을 혈액내에서 확인할 수 있었다.

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자연 건조 조건에 따른 니트 소재 수축 (Shrinkage of Knitted Fabric Depending on the Condition of Air Drying)

  • 주정아;경문수;김지훈;박용완;김상영;오영기
    • 한국의류학회지
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    • 제41권6호
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    • pp.1050-1059
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    • 2017
  • Drying processes often cause knitted fabrics to shrink. This study obtains proper drying conditions for in the dryer use that can minimize knitted fabric shrinkage by investigating changes in shrinkage according to drying conditions. The experiment samples were all machine washable plain, mesh, and lacoste knitted fabrics made of 100% cotton. Samples were first washed in a washing machine on a normal cycle. They were then layered on a flat surface in an artificial climate chamber and dried for 24 hours at $20^{\circ}C$ and $40^{\circ}C$, respectively. Shrinkage was measured for 180 minutes at 30 minute intervals after washing. The comparison results of the shrinkage in the washing and drying process indicate that 80.0% and 23.0% shrinkage of plain knitted and lacoste knitted fabrics occurred during the washing process. As the samples dried, the shrinkage of the plain and lacoste knitted fabrics then rapidly increased after approximately 30.0% moisture content. The highest air drying shrinkage occurred over one cycle with insignificant changes in shrinkage after repeated treatments.

방사상 배전계통의 손실감소 및 전압보상을 위한 커패시터 최적 배치 및 운용 (Optimal Capacitor Placement and Operation for Loss reduction and Improvement of Voltage Profile in Radial Distribution Systems)

  • 김태균;백영기;김규호;유석구
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 하계학술대회 논문집 D
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    • pp.1009-1011
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    • 1997
  • This paper presents an optimization method which determines locations and size of capacitors simultaneously while minimizing power losses and improving voltage profile in radial distribution systems. Especially, the cost function associated with capacitor placement is considered as step function due to banks of standard discrete capacities. Genetic algorithms(GA) are used to obtain efficiently the solution of the cost function associated with capacitors which is non-continuous and non-differentiable function. The strings in GA consist of the node number index and size of capacitors to be installed. The length mutation operator, which is able to change the length of strings in each generation, is used. The proposed method which determines locations and size of capacitors simultaneously can reduce power losses and improve' voltage profile with capacitors of minimum size. Its efficiency is proved through the application in radial distribution systems.

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1, 4-디히드로피리딘산 유도체의 새로운 제조방법에 관한 연구 (New Synthetic Route to 1, 4-Dihydropyridine Monoacid Derivatives)

  • 심영기;이상희;강재성;김완주
    • 대한화학회지
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    • 제32권2호
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    • pp.144-148
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    • 1988
  • 의약적으로 매우 유용한 1,4-디하히드로피리딘 3,5-디카르복실산 에스테르의 중간체인 1,4-디히드로피리딘 모노 유기산(V)을 알릴에스테르(IV)에 팔라듐 아세테이트 촉매를 사용하여 94%의 높은 수율로 얻었으며 이 중간체를 사용하여 2-(N-벤질-N-메틸아미노) 에틸메틸 2,6-디메틸-4-(3'-니트로페닐)-1,4-디히드로피리딘-3, 5-디카르복실산 에스테르(VII) 및 그 유도체들을 70~85%의 좋은 수율로 합성하였다.

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공동주택 기계실 난방설비 운전 개선 연구 (A Study on Improved Operation of Apartment Heating System in a Machine Room)

  • 서정아;신영기;김용기;이태원
    • 설비공학논문집
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    • 제29권1호
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    • pp.38-42
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    • 2017
  • This study proposes an idea for energy saving in apartment machine rooms. A conventional district heating system is equipped with constant-flow pumps and bypass valves to regulate pump differential pressure. Each family unit is equipped with a constant-flow on/off valve. This leads to excessive hot water circulation and a high return temperature. To reduce energy loss, this study assumes that each family unit is renovated with a heating valve which regulates the return temperature at $35^{\circ}C$. The hot water supply pump is also replaced with a pump with an inverter to vary flow rate. Expected energy savings is then estimated from field test data. According to the results, pump electricity consumption was reduced by 6,100 kWh for a family unit building over about half a year. The supply temperature can also be lowered by $5^{\circ}C$, which can contribute to a production of electricity of 10.3 kWh/ton of hot water.

흰쥐 시상하부의 정중융기에서 카테콜아민 신경세포와 GnRH 신경세포와의 연접에 관한 연구 (Catecholaminergic Innervation of GnRH Neurons in the Rat Median Eminence)

  • 이영기;김경진
    • 한국동물학회지
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    • 제37권4호
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    • pp.504-513
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    • 1994
  • The present study was carried out 1) to show the ontogenic development of CA-and GnRH-containing nerve fobres in the median eminence, 2) to simultaneously demonstrate the synaptic contact between these two nenre fibres in the rat median eminence at the ultrastructural level using light and electron microscopic doublelabel immunostainlngs. GnRH-and CA-nenre terminals were detectable in the median eminence at embryonic day 19.5. The CA-newe terminals were obsenred in the entire legion of the extern31 lavers, while GnRH-newe terminals only in the lateral portion. At the 14th postnatal daw, both %ropes of nerve terminals showed a very similar distribution to those of adult one. In the median eminence of adult rats, a substantial overlap existed in the distribution of GnRH fibres with CA-containing nerve fibres. This overlap was most intense throughout the external palisade zone. Furthermore, an electron microscopic double label immunostaining showed that there was a close apposition of CA- and GnRH-nenre fobres. These axo-axonic contacts occurred frequently in the internal and palisade zones, i.e. at the level of the fobre preterminals. These morphological results suggest that the CA-mediated GnRH secretion may occur via sxo-axonic interaction in the median eminence.

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TJ 커플러 제작용 멀티 절아두이노를 이용한 화재대피시스템 구현삭기 (Implementation of Fire Evacuation System using Arduino)

  • 박차훈;원흥섭;김영욱;김정근;황해수;박영기
    • 한국컴퓨터정보학회:학술대회논문집
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    • 한국컴퓨터정보학회 2017년도 제56차 하계학술대회논문집 25권2호
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    • pp.405-406
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    • 2017
  • 본 논문에서는 아두이노와 이더넷 쉴드 및 스마트폰 어플리케이션을 활용하여 화재 감지와 안전한 대피 경로를 제시하는 자동화 시스템을 제안한다. 실시간으로 구역별 각 정보를 얻을 수 있고, WS2812S를 활용한 가장 안전하고 단거리의 대피로를 제시할 것이다. 구현 시스템은 아두이노 메가를 이용하였고, 이더넷 쉴드를 통해 연결된 센서들이 정보를 지속적으로 읽고 공통 네트워크로 연결된 컴퓨터나 모바일에 정보를 통신한다. 그리고 대피 경로 상의 환풍기를 효율적으로 컨트롤하여 안전성을 증가시키고 화재 위험지역과 대피 안전지역을 구분하여 실제 상황 발생 시에도 원활한 대응에 도움을 줄 것이다. 또한 아두이노를 이용한 화재대피시스템은 사고 발생 초기에 현장과 떨어진 지역에서 작업하여 사고 발생에 대해 정보를 정확히 알 수 없는 부분을 해결하고자 대피 안내 방송을 하여 인명피해를 최소한 하고자 제안하였다.

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한우태자의 기관연골 발생에 관한 형태학적 연구 (Morphological studies on the development of the tracheal cartilage in the Korean native cattle fetus)

  • 이영훈;김인식;양홍현;백영기
    • 대한수의학회지
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    • 제37권1호
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    • pp.15-24
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    • 1997
  • This study was undertaken to obtain basic data on the histological changes in the tracheal cartilage of the embryos and fetuses of the Korean native cattle. Twenty-two embryos and fetuses of the Korean native cattle, ranging from 30mm(peesumptive fetal age 44 days) to 440mm(presumptive fetal age 168 days) in crown-nump(C-R) length, were used for present study. The results were summerized an follows; 1. Mesenchymal cells differentiated as chondroblasts were condensed into tracheal cartilage in the CRL 30mm of the Korean native cattle embryo, and the chondrocytes begun to appear in the tracheal cartilage in the CRL 40mm fetus. 2. The tracheal cartilage in the CRL 70mm fetus was composed of the large number of chondrocytes. The histochemi8cal reactions for glycosaminoglycans showed strong positive reaction in the CRL 380mm, and for collagen substance showed mildly in the 6th experimental group.

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