• Title, Summary, Keyword: Contact type

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Comparison of Collecting Performance according to Contact Types of Heatpipe in Vacuum Tube Type Solar Collector (진공관형 집열기 히트파이프 접촉방식에 따른 집열성능 비교)

  • Yun, Ji-Hun;Jeong, In-Guk;Yi, Chung-Seob;Chung, Kyung-Teak;Suh, Jeong-Se
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.6
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    • pp.122-127
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    • 2011
  • In this study, it was compared collecting performance according to contact types between heatpipe and manifold of vacuum tube type solar collector. Between two types, direct contact type is better in collecting performance. On the other hand, Indirect type have advantage in maintenance. In the result of numerical analysis, As the temperature of heatpipe and flow rate of working fluid increased, difference of outlet mean temperature of two types became large. Also, it could be confirmed, as contact resistance between heatpipe and copper tube in indirect type increased, the difference increased too. Useful data in selection and design in vacuum tube type solar collector were proposed by the results of numerical analysis.

Optical characteristics of the UV intensity distribution in a non-contact type UV photoreactor (비접촉식 자외선 반응조에서 자외선 강도 분포의 광학적 특성)

  • Jeon, Hwa-Bong;Yun, Jung-Won;Kim, Sung-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.2
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    • pp.257-264
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    • 2012
  • The concept of a non-contact type of UV disinfection system was introduced in this study. UV lamps and their quartz sleeves hang over the water surface and there is no interface between the sleeve and water. Obviously, there is no fouling. Based on optical laws and other UV distribution models, a detail mathematical model for a non-contact type UV disinfection system was developed in this study. Pathway length of UV light in a non-contact type photoreactor is longer than that in a submerged type photoreactor because the light is more refractive while passing through 3 interfaces of medium. But the pathway length passing through the water media is not significantly longer than that in a submerged type photoreactor so, the absorption of UV light by water is not significantly different from the other system. Due to the reflection effect, UV intensity is rapidly decreased as the horizontal distance from the light source is increased. The reflective attenuation in a non-contact type photoreactor is higher than that in a submerged type photoreactor. These mean that the short photoreactor is advantageous than the narrow-long photoreactor for the non-contact type photoreactor in an optical point of view.

SMALL MASS RATIO CONTACT BINARY (질량비가 작은 접촉쌍성)

  • 오규동;김천휘;강영운;김용기
    • Journal of Astronomy and Space Sciences
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    • v.20 no.2
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    • pp.133-142
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    • 2003
  • The contact binary system has been classified in five different types according to their physical properties. We suggest that extremely small mass ratio contact binary systems(q<0.2) could be classified as a new type of contact binaries in addition to the classification. According to the Svechnikov & Kuznetsova (1990)'s catalogue, the spectral types of primary components of newly classified contact binaries are distributed at A type, and also the distribution of their various physical characteristics is laid at the center region dividing the early-type contact binaries from late-type contact binaries.

GRADIENT EINSTEIN-TYPE CONTACT METRIC MANIFOLDS

  • Kumara, Huchchappa Aruna;Venkatesha, Venkatesha
    • Communications of the Korean Mathematical Society
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    • v.35 no.2
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    • pp.639-651
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    • 2020
  • Consider a gradient Einstein-type metric in the setting of K-contact manifolds and (κ, µ)-contact manifolds. First, it is proved that, if a complete K-contact manifold admits a gradient Einstein-type metric, then M is compact, Einstein, Sasakian and isometric to the unit sphere 𝕊2n+1. Next, it is proved that, if a non-Sasakian (κ, µ)-contact manifolds admits a gradient Einstein-type metric, then it is flat in dimension 3, and for higher dimension, M is locally isometric to the product of a Euclidean space 𝔼n+1 and a sphere 𝕊n(4) of constant curvature +4.

Analysis of Contact Stress in Slewing Ring Bearings (슬루잉 링 베어링의 접촉응력분포에 관한 연구)

  • 김청균;이승렬
    • Tribology and Lubricants
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    • v.11 no.2
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    • pp.24-33
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    • 1995
  • This paper presents the contact stress distributions between the multi-contact bodies and the total reaction forces for various types of contact geometry for multi-load slewing ring bearings. The FEM results indicate that the slope of the roller type of slewing ring bearing has slightly steeper than that of the ball type. This is because the roller type wire race bearings is stiffer than the ball type bearing. The total reaction force of ball type slewing bearing shows much higher than that of wire race slewing bearings.

Wear Resistance Evaluation of Contact Tip according to Flux Cored Wire (플럭스 코어드 와이어에 따른 용접 중 콘택트 팁 내마모성 평가)

  • Kim, Dong-Yoon;Hwang, In-Sung;Kim, Dong-Cheol;Kang, Moon-Jin
    • Journal of Welding and Joining
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    • v.31 no.4
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    • pp.42-46
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    • 2013
  • The contact tip for flux cored arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. A damaged contact tip causes a productivity reduction and a welding quality problem. In this study, the welding experiments for the wear resistance of contact tip regarding flux cored wire types were performed. With two fold type and a seamless type flux cored wires, the wear rates of contact tips were compared. In addition, the wear rate was checked according to the contact tip position.

Non-contact type AFM using frequency separation scheme (주파수응답 분리방법을 이용한 비접촉식 AFM)

  • 이성규;염우섭;박기환;송기봉;김준호;김은경;박강호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.375-378
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    • 2002
  • In this paper, the frequency response separation scheme is proposed for high scanning speed and simple structure of non-contact type of AFM. A self-sensing cantilever is attached on the actuator for detect the atomic force between tip and the media surface. VCM or PZT are used for actuator. This paper presents the method to simplify the actuator structure and the performance of each actuator for non-contact type AFM. Based on the frequency response separation scheme, the only one actuator plays roles 1311owing low frequency surface and modulating self-sensing cantilever tip in contrast with convention non-contact type AFM. 10 ${\mu}{\textrm}{m}$ standard grid sample imaged to verify proposed scheme. This result shows the possibility simplifying the actuator structure and reducing cost of non-contact type AFM.

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Asymmetric Light curves of Contact and Near-Contact Binaries

  • Rittipruk, Pakakaew;Kang, Young-Woon
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.143.1-143.1
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    • 2012
  • We attempt to investigate the main reason of the asymmetrical light curves of contact and near-contact eclipsing binary base on the hypothesis that cool spot was produced on late type star while hot spot was produced from transferred material from their companion star hitting surface. We select 7 eclipsing binary systems which showed asymmetric light curves and mass transfer. Period variation and mass transfer rate were obtained from O-C diagram. Radial velocity curves and light curves of those 7 eclipsing binary system were adopted from available literature in order to obtain the absolute dimension. For four contact eclipsing binary system (AD Phe, EZ Hya, AG Vir and VW Boo), their component stars belonged to spectral type G to K was fitted by cool spot model. While the other two near-contact systems (RT Scl and V1010 Oph) and one contact system (SV Cen) was fitted by cool spot model. The densities of the materials are adopted from stellar model which calculate by stellar structure code. The calculated spot temperature turns out to agree with the photometric solution but there are no correlate between period variation rate and type of spot.

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Characteristics of Ni/Ti/Al ohmic contact on Al-implanted 4H-SiC (Al 이온 주입된 p-type 4H-SiC에 형성된 Ni/Ti/Al ohmic contact의 특성)

  • Joo, Sung-Jae;Song, Jae-Yeol;Kang, In-Ho;Bahng, Wook;Kim, Sang-Cheol;Kim, Nam-Kyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.208-209
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    • 2008
  • Ni/Ti/Al multilayer system was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Compared with conventional process using Ni, Ni/Ti/Al contact shows perfect ohmic behavior, and possesses much lower contact resistance of about $2.5\times10^{-4}\Omega{\cdot}cm^2$ after $930^{\circ}C$ RTA, which is about 2 orders of magnitude smaller than that of Ni contact. Contact resistance gradually increased as the RTA temperature was lowered in the range of 840 ~ $930^{\circ}C$, and about $3.4\times10^{-4}\Omega{\cdot}cm^2$ was obtained at the lowest RTA temperature of $840^{\circ}C$. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance.

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Bleaching Observation of Cosmetic Color Lenses According to Multipurpose Contact Lens Solutions (다목적 콘택트렌즈 용액에 대한 미용 칼라렌즈의 탈색 관찰)

  • Kim, Hyojin
    • Journal of Korean Ophthalmic Optics Society
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    • v.19 no.3
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    • pp.295-303
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    • 2014
  • Purpose: This study aims to observe bleaching resulted from multipurpose contact lens solutions used to manage lenses with the subjects of colored contact lenses being distributed in Korea. Methods: The lenses have been worn for six months, and their refraction is 0.00D. Three types of colored contact lenses of which margin has been colored with a different manufacturing method have been adopted (type 1: pigment application method, type 2: chemical bonding process, type 3: sandwich method), and multipurpose solutions used were two types containing different components. Each of the colored contact lenses was stored in the multipurpose solutions for 20 days and went through vortexing for 15 seconds per day. Their fluorescence absorbance, surface roughness, brightness index, and color coordinate index were measured before and after the vortexing to see the degree of bleaching. Results: In the two types of multipurpose solutions, every type of the color contact lenses showed no statistically significant difference in their fluorescence absorbance value before and after the vortexing. Regarding surface image, the front surface of the lenses was smooth in every type, and about the back surface, type 3 indicated less protrusion than type 1 and 2. About the difference of color on the lens surface before and after the vortexing, type 3 showed significantly less difference than type 1 and 2; however, all fell into the permissible error. Conclusions: About the bleaching of colored contact lenses resulted from multipurpose solutions for soft contact lenses, there was no difference observed in terms of fluorescence absorbance and color. According to the methods of manufacturing dyes, however, there was difference in the protrusion of the posterior surface image.