• Title, Summary, Keyword: 표면거칠기

Search Result 653, Processing Time 0.043 seconds

Heat Transfer Enhancement of Water Spray Cooling by the Surface Roughness Effect (표면거칠기 효과에 따른 스프레이 냉각의 열전달 향상 연구)

  • Lee, Jung-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.34 no.2
    • /
    • pp.203-212
    • /
    • 2010
  • Water spray cooling has been widely used in a variety of industrial applications. The present study concentrated on quantitative measurements of the heat flux and heat transfer coefficient by water spray as it impinges on the rough surface of a hot steel plate at $900^{\circ}C$. A novel experimental technique was developed for a hightemperature heat flux gauge with a test block, cartridge heaters, and thermocouples that was used to measure the surface heat flux information on the hot steel plate for local heat flux measurements. The roles of the surface roughness on heat transfer are presented in this paper for well-characterized four rough surfaces with average rms roughness heights of $40-80{\mu}M$. The results show that the local heat transfer for rough surfaces is higher than that for a smooth surface. Heat transfer can be significantly increased by the presence of surface roughness elements, which can disrupt the thin thermal boundary layer. In addition, the heat transfer enhancement mechanism on a rough surface can be investigated by a different boiling regime.

Evaluation of Adhesion Property of Epoxy Adhesive with Different Surface Roughness of GFRC (유리섬유강화 복합재료의 표면거칠기에 따른 에폭시 접착제의 접착강도 평가)

  • Kim, Jong-Hyun;Shin, Pyeong-Su;Lee, Sang-Il;Park, Joung-Man
    • Journal of Adhesion and Interface
    • /
    • v.21 no.1
    • /
    • pp.27-33
    • /
    • 2020
  • Adhesion property of epoxy adhesive was evaluated with different surface roughness of glass fiber reinforced composite (GFRC) and optimized condition of surface roughness was confirmed. Different sizes of alumina (Al2O3) particles were blasted to GFRC to control surface roughness of GFRC using sand blasting method. The surface roughness was measured and quantified via surface roughness tester. Contact angle was measured using four types of different solvents. Surface energies and work of adhesion between epoxy adhesive and GFRCs were calculated with different surface roughness of GFRC. Adhesion property between epoxy adhesive and GFRCs was evaluated using single lap shear test and adhesion property increased with surface roughness of GFRC. The fracture surface of GFRCs was observed to evaluate adhesion property. Finally, the optimized roughness condition of GFRCs was confirmed.

Effect of surface roughness onto the scattering in low loss mirrors (기판의 표면거칠기와 반사경 산란에 대한 연구)

  • 조현주;신명진;이재철
    • Korean Journal of Optics and Photonics
    • /
    • v.13 no.3
    • /
    • pp.209-214
    • /
    • 2002
  • The effect of surface roughness on mirror scattering has been studied. Five kinds of substrates with different surface roughness were fabricated. On those substrates, a dielectric multi-layer coating with high reflectivity was deposited by ion beam sputtering and electron beam evaporation. A total integrated scattering measurement set-up was built for the evaluation of deposited samples. Most of the ion beam sputtered mirrors showed lower scattering than the electron beam evaporated one, which deposited on substrates similar in surface roughness. Over ~2 $\AA$ in surface roughness, scattering strongly depend on the micro-structure of the super-polished surface. The lowest scattering we have achieved is 2.06 ppm by ion beam sputtering from the substrate with surface roughness of 0.23 $\AA$.

Surface Smoothing of Blasted Glass Micro-Channels Using Abrasive Waterjet (워터젯을 이용한 블라스팅 유리 마이크로 채널의 표면거칠기 개선)

  • Son, Sung-Gyun;Han, Sol-Yi;Sung, In-Ha;Kim, Wook-Bae
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.37 no.12
    • /
    • pp.1159-1165
    • /
    • 2013
  • Powder blasting, which is an efficient micromachining method for glass, silicon, and ceramics, has a critical disadvantage in that the surface finish is poor owing to the brittle fracture of materials. Low-pressure waterjet machining can be applied to smoothen the rough surface inside the blasted structure. In this study, the surface roughness and sectional dimension of micro-channels are observed during the repetitive application of a waterjet to blasted micro-channels. The asperities and subsurface cracks created by blasting are removed by waterjet machining. Along with the surface roughness, it is found that the sectional dimension increases and the edges of the finished micro-channel become slightly round. Finally, a microfluidic chip is machined by the blasting-waterjet process and a transparent microfluidic channel is obtained efficiently.

A Study on the Influence of the Standard Filter and Phase-Corrected Filter for the Surface Roughness Measurement on the Value of Surface Roughness (표면거칠기 측정용 표준필터와 위상보상형 필터의 위상특성이 표면거칠기 값에 미치는 영향에 대한 연구)

  • 한응교;노병옥
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.13 no.1
    • /
    • pp.67-76
    • /
    • 1989
  • Although the standard 2-CR network filter, one of the filters used for measuring surface roughness, is being used widely in the field of industry it possesses a weak point of causing Phase-distortion when the wavelength is passing through. Phase-corrected filter is used for eliminating these phase-distortion and the difference of phase characteristics between these two filters is thought to have considerable amount of effect on the surface roughness value. Moveover, the definition on this is as yet unclear. Therefore, the Rt and Rz value, obtained when the wavelength are passed through the standard and phase-corrected filters from the same random machine-processed surface, and its standard deviation are compared and experimented in this paper. Also, the ratio of relative bearing curve complying to the phase characteristics of these two filters are acquired. As a result, the use of phese-corrected filter is appropriate in experiments where the form of wavelength is important, and the standard deviation on the same experimented values appeared greater with when using the standard filter. The rate of relative bearing curve became greater as .lambda.$_{c}$, the cut-off value of filter, became smaller.r.

고분자 담체에 대한 혐기성 미생물의 초기부착에 관한 연구

  • 박성열;박영식;이승란;이창한;이송우;송승구
    • Proceedings of the Korean Environmental Sciences Society Conference
    • /
    • /
    • pp.206-207
    • /
    • 2000
  • 고분자 담체의 경우 표면의 화학적 성질인 소수성과 물리적 성질인 표면거칠기는 미생물 부착과 관련이 있지만 두 요소 중, 표면거칠기의 영향이 더 크다고 볼 수 있으며 담체 표면의 소수성이 작고 표면거칠기가 클수록 혐기성 미생물이 잘 부착되었다.

  • PDF

Sub-${\AA}$ surface roughness measurement using phase-measuring interferometer (위상측정 간섭계를 이용한 sub-${\AA}$급 표면거칠기 측정)

  • 조민식;정태호;오문수;이수상;이재철
    • Proceedings of the Optical Society of Korea Conference
    • /
    • /
    • pp.176-177
    • /
    • 2000
  • 고분해능 분광학, 레이저 주파수 안정화, 단원자 레이저, 레이저 자이로 등의 다양한 분야에서 널리 응용되는 저손실, 고반사율 반사경 제작은 고품질의 반사경 기판 사용을 전제로 하고 있다. 1$\AA$이하의 표면거칠기(surface roughness)를 요구하는 반사경 기판의 초연마(super-polishing) 기술과 저손실 반사경 박막코팅 기술은 최근 수 년 사이에 상당한 발전이 이루어졌으며, 이와 함께 초연마 반사경 기판의 표면거칠기 측정기술이 중요한 분야로 주목받고 있다. 표면거칠기 측정기법은 현재까지 여러 가지 방법이 연구, 발전되어 왔는데, 접촉식 측정방법으로 stylus 방법과 비접촉식 측정방법으로 광학 간섭계 방법, 스캔닝 전자현미경(SEM, Scanning Electron Microscopes) 등이 있다. 이들 중 광학 간섭계 방법은 표면형상을 직접 측정 가능하다는 점에서 유망한 비접촉 표면측정 기법으로 알려져 있다. (중략)

  • PDF

The Effect of Hydrogenation on the Elecrical Property and the Surface Roughness of Poly-$\textrm{Si}_{1-x}\textrm{Ge}_{x}$ Thin Film (수소화처리가 다결정 $\textrm{Si}_{1-x}\textrm{Ge}_{x}$박막의 전기적특성 및 표면거칠기에 미치는 영향)

  • Lee, Seung-Ho;Lee, Gyu-Yong;So, Myeong-Gi;Kim, Gyo-Seon
    • Korean Journal of Materials Research
    • /
    • v.8 no.1
    • /
    • pp.71-79
    • /
    • 1998
  • RTCVD법으로 증착된 다결정 Si$_{1-x}$Ge$_{x}$박막에서 Ge조성 증가에 따른 결정립크기변화가 표면거칠기 및 cluster크기에 미치는 영향에 대해 알아본결과, Ge조성 증가에 따라 결정립크기가 증가했으며 증가된 결정립에 의해 Cluster 크기와 표면거칠기값(RMS)들이 증가함을 알 수 있었다. 또한 증착된 다결정 Si$_{1-x}$Ge$_{x}$박막을 RF power와 온도변화에 따라 Ar/H$_{2}$플라즈마를 이용한 수소화처리를 행하여, 수소화 효과와 표면거칠기값 그리고 비저항값 변화에 대해 조사하였다. 수소화처리 후 cluster크기와 표면거칠기값은 기판온도와 RF power 증가에따라 감소함을 알 수 있었으며 특히 기판온도 30$0^{\circ}C$에서는 비저항값이 상당히 증가하였다.

  • PDF

Machining characteristics of micro end-mill using high revolution (고속회전을 이용한 마이크로 엔드밀의 가공특성)

  • Kim, Kisoo;Kim, Sangjin;Cho, Byoungmoo;Kim, Hyeungchul
    • 대한공업교육학회지
    • /
    • v.31 no.2
    • /
    • pp.350-363
    • /
    • 2006
  • Recently, the micro end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in milli-structure parts, micro machine parts and molding industry. The cutting conditions of micro end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to cut stainless steel using high revolution air bearing spindle and micro end-mill and analyze the cutting condition to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on depth of cut, revolution of spindle and feed.