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검색결과 669건 처리시간 0.025초

Operating Characteristics of Counterrotating Floating Ring Journal Bearings

  • Cheong, Yeon-Min;Kim, Kyung-Woong
    • KSTLE International Journal
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    • 제2권2호
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    • pp.127-132
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    • 2001
  • The steady state performance of the counterrotating floating ring journal bearings is analyzed with isothermal finite bearing theory. The effect of counterrotating speed of the sleeve on the performance of the bearing is investigated. It is shown that counterrotating floating ring journal bearings can have considerable load capacity at the same counterrotating speeds, while conventional circular journal bearings with one fluid film cannot. Investigating the relationship between the frictional torques exerted on the ring due to the inner and outer films and the rotational speed of the ring, the stability of the equilibrium state is identified and the operating characteristics of the counterrotating floating ring journal bearing according to the method of acceleration or deceleration of the rotational speeds of the journal and sleeve are clarified. It is theoretically confirmed that floating ring journal bearings can be used in counterrotating journal-bearing system and become good substitutes for rolling bearings in counterrotating systems.

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농촌어메니티 자원조사감리방법론 개발과 전략계획 (Developing the Auditing Methodology and Strategic Planning of Rural Amenity Resources Investigation)

  • 서보환
    • 농촌계획
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    • 제14권2호
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    • pp.99-110
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    • 2008
  • The purposes of this paper are first, to develop and adapt auditing methodology of rural amenity resource investigation and second, to propose strategic planning of amenity web data base system. Relating with auditing methodology, we make the life cycle of rural amenity resource investigation based on value chain method. we make 8 stage of auditing process and 105 auditing items in details. We adapt these guidelines in real world and then improve developed methodology. Therefore we expect to promote the quality and accuracy of investigation project using these guidelines. Relating with blue print of strategic planning, we first analyse external environment about Competitors, Suppliers, New entrants, Buyers, Substitutes with 5 force model for amenity information system. We second make the blue print of strategic planning of amenity web data base system project. Then we propose the FIRST, BEST, MOST strategy of amenity web data base system and the web hub system.

한국전통복색에서의 청색과 흑색 - 청색의 범주문제를 중심으로 - (A Study on the Bule and Black Colors in Korean Traditional Costume - About the Categroy of Blue Color -)

  • 이은주
    • 한국의류학회지
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    • 제18권1호
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    • pp.121-129
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    • 1994
  • A study focused on the implication of the blue and black colors in Korean traditional costume is presented. The presented study shows that the blue color in most of literatures regarding Korean traditional costume implies not only green and blue colors, but also dark blue and black colors. In a broad sense, the blue color implies a color category which includes green, indigo, blue, dark blue and black. On the other hand, the color includes blue, dark blue and black in a narrow sense. The rotor black, however, should not be interpreted as blue and dark blue because it has two bypes of black colors with and without reddish tone. Four reasons that the color blue was understood as the color black were discussed in this paper. The fundamental reason was that the blue color looked like black because of dark shadows. Secondly, there was a difference of color awareness between the color blue in Korea and in China. Thirdly, there was a color difference related to the type of textiles. Finally, other substitutes were used because of the lack of blue dyes.

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쓰레기 소각재를 혼입한 콘크리트의 재료특성 및 강도특성 (Properties of Concrete Mixed with Waste Incinerated Bottom Ash)

  • 어석홍;홍기호;최덕진;김희성
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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    • pp.217-222
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    • 2002
  • The purposes of this study are to investigate the material characteristics and strength properties of concrete mixed with waste incinerated bottom ash(BA), and to evaluate the leaching of environmentally harmful heavy metals from the bottom ash itself and from hardened concrete mixed with bottom ash. For this purpose, two reference mixes with W/C ratios of 0.45 and 0.55 were used, and the replacement proportion of BA was varied with the ratios of 0%, 30%, 50%, 70%, and 100% by volume of fine aggregate in the reference mixes. The variation of compressive and splitting tensile strength, workability and unit weight of concrete were considered. Test results showed that the strengths, workability and unit weight decreased with increase in proportion of BA replaced. Leaching test results showed that there would be no environmentally harmful problem from using BA as the substitutes of fine aggregates in concrete.

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A Study of Antioxidant and Antibacterial Activates of the Extraction of Perscaria hydropiper L.

  • Oh, Sun-Min;Oh, Kwang-Yul;Ahn, Sun-Choung
    • 한국조리학회지
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    • 제22권6호
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    • pp.14-23
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    • 2016
  • This purpose of this study is to examine the antioxidant and antimicrobial activities of Persicaria hydropiper L. extract in 70% ethanol and in water, a medicinal herb, as an effort to examine the potential of medicinal herbs for development of antioxidants and natural preservative substitutes. The total poly-phenol content in the 70% ethanol extract and in the water extract were 19.88 mg/g and 7.46 mg/g, respectively. The DPPH radical scavenging activity was 90.99% and 64.98% in the 70% ethanol extract and water extract, in which 70% ethanol extract showed a higher activity. The antioxidant effect of Persicaria hydropiper L. extract appears to be very good and due to its excellent growth inhibitory effect on food-poisoning-causing microorganisms in the food, it is thought to be utilized as a potential natural preservative substitute in many areas.

Fabrication of transparent conductive thin films with Ag mesh shape using the polystyrene beads monolayer

  • Jung, Taeyoung;Choi, Eun Chang;Hong, Byungyou
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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    • pp.313-313
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    • 2016
  • Transparent conductive oxide (TCO) films have many disadvantages, such as rarity, possible exhaustion, process temperature limitations, and brittleness on a flexible substrate. In particular, as display technology moves toward flexible displays, TCO will become completely unsuitable due to its brittleness. To address theses issue, many researchers have been studying TCO substitutes. In recent efforts, metal nanowires, conducting polymers, carbon nanotube networks, graphene films, hybrid thin films, and metal meshes/grids have been evaluated as candidates to replace TCO electrodes. In this study, we fabricated the TCO film with Ag meshes shape using polystyrene (PS) beads monolayer on the substrate. The PS beads were used as a template to create the mesh pattern. We fabricated the monolayer on the flexible substrate (PES) with the well-aligned PS beads. Electrodes with Ag mesh shape were formed using this patterned monolayer. We could fabricated the Ag mesh electrode with the sheet resistance with $8ohm{\Omega}/{\Box}$.

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Numerical Study of Important Factors for a Vortex Shedder using Automated Design Cycle

  • Nyein, Su Myat;Xu, He
    • International Journal of Fluid Machinery and Systems
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    • 제8권3호
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    • pp.124-131
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    • 2015
  • The good performance of a vortex shedder is defined by strong and stable vortex generated under the condition of most linearity in Strouhal number and low power loss. In this paper, the flow past a bluff body of circular cylinder with a slit normal to the flow has been analyzed focusing on drag coefficient, linearity of Strouhal number and flow resistance (K-factor). The ANSYS/FLUENT package is used for flow simulation and the integration method of computational code to iSIGHT platform is employed for automated design cycle. This study results the design with (0.20~0.267) blockage ratio and 0.10 slit ratio as the best shedder for vortex flowmeter and this results are in well agreement with the experiment. As the combination of GAMBIT, FLUENT, and iSIGHT substitutes the design parameters automatically according to the input data, this method designs effectively the vortex shedder with less design cycle time and low manufacturing cost eliminating the human intervention bottleneck.

개구-정합 형태를 갖는 UWB용 슬롯 안테나의 설계 (Dsign of Aperture-Matched type Slot Antenna for Ultra Wide-Band)

  • 문병인;김호용;이홍민
    • 한국전자파학회:학술대회논문집
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    • 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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    • pp.217-220
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    • 2005
  • In this paper describes novel m antenna using aperture matched type slot structure. It substitutes edge diffractions by curved-surface diffractions which have a tendency to provide an undisturbed energy flow across the junction, around the curved surface, and into free-space. The proposed antenna is composed of a CPW feed structure, exponential tapered slot and the curved sectional at the edge. experimental resulte show that aperture matched type slot improve the performance of the UWB antenna.

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Transesterification for FAME production of Rapeseed Oil

  • 정귀택;윤대현;강춘형;최병철;이운택;박돈희
    • 한국생물공학회:학술대회논문집
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    • 한국생물공학회 2003년도 생물공학의 동향(XII)
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    • pp.164-168
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    • 2003
  • 유채유를 사용하여 바이오디젤 생산을 위한 1단 전이에스테르화 공정에 있어서 반응온도 $60^{\circ}C$, 유지에 대한 메탄올 몰비 1:10 이상, 1.0 % (w/w) 포타슘 하이드록시드의 조건에서 98.5% 이상의 전화율을 얻을 수 있었다.

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Measurement of Synergistic Effects of Binary Sweetener Mixtures

  • Chung, Hai-Jung
    • Preventive Nutrition and Food Science
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    • 제2권4호
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    • pp.291-295
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    • 1997
  • Some sensory properties of synthetic sweeteners are limiting factors for use in low calorie foods of soft drinks. By combining synthetic sweeteners(Neohesperidin dihydrochacone(NHDC), stevioside) with sucrose, sorbitol or xylitol, these limitations can be overcome. Using trained taste panelists and magnitude estimation methods, synergistic effects were investigated in binary sweetener mixtures, The results showed that synergism, as much as 28% to 69%,was noted at all concentration in xylitol-stevioside, NHDC-stevioside mixtures. Synergistic effects were found only at high concentration levels in mixtures of sucrose-NHDC, sucrose-stevioside, and sorbitol-stevioside, ranging from 11% to 22%.By taking advantage of synergistic effects, ginseng tea and orange flavored beverages, sweetened with either xylitol-stevioside of NHDC-stevioside, were prepared and the sensory quality was compared with that of sucrose containing beverages. It was found that sensory characteristics were judged to be very similar for all formulations. The result suggests the possibility of using of using these sweetener mixtures as sugar substitutes in ginseng tea and orange drink.

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