• Title, Summary, Keyword: 표면조도

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알루미늄 도관의 내표면 화학연마

  • Gwon, Hyeok-Chae;Na, Dong-Hyeon;Hong, Man-Su;Ha, Tae-Gyun;Park, Jong-Do
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.205.1-205.1
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    • 2014
  • 4세대 가속기 언듈레이터 진공용기는 길이가 6 m이고 내경이 $7{\times}11mm$로 매우 좁아서 내부 표면의 경면연마가 까다롭다. 미국이나 독일의 경우 입자유동연마 방법으로 표면 거칠기와 표면 산화막 두께를 요구되는 수준으로 낮췄다. 이 방법을 적용해 본 결과, 연질의 알루미늄 표면에 스크레치 및 피트 발생율이 높고 고비용에 처리시간이 길다는 단점이 있었다. 포항가속기에서는 입자유동연마와 병행하여 화학연마 방법으로 관경이 좁은 형상이나 길이에 구애받지 않고 긴 진공용기 크기의 약품조가 없이 표면연마 할 수 있는 장치를 고안하였다. 이 장치는 표면조도 개선 목적의 화학연마, 표면 산화막 두께 개선, 세척 및 건조장치가 한 시스템으로 구성되어 큰 약품조와 수세조가 필요하지 않다는 장점이 있어서 입자유동연마 공정을 대체할 수 있는 방법으로 기대된다. 본 발표에서는 화학연마 장치에 대해 소개하고 연마 전 후 표면조도와 산화막 개선 결과에 대해서 논하고자 한다.

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Development of the Handy Non-contact Surface Roughness Measurement Device by using the Optical Fiber Sensor (광섬유센서에 의한 간이 비접촉 표면조도 측정기의 개발)

  • Hong, Jun-Hee
    • 대한공업교육학회지
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    • v.34 no.2
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    • pp.346-362
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    • 2009
  • The purpose of this study was to develop the handy non-contact measurement device of the surface roughness by using the optical fiber sensor. The advantages of fiber optic sensors are high-speed responsibility, non-effect of the magnetic, convenience of the product and high precision. The measurement theory for surface roughness of optical fiber sensor is one to one correspondence between the reflected light intensity based on the surface roughness of the object and the measurement value of previously known for surface roughness. The reflected light intensity was determined using the distance to the surface from the sensor probe and the limit reflection angle based on the surface roughness. Therefore, in this study, the sensor probe was produced for determining the value of surface roughness only using the limit reflection angle based on the surface roughness with the fixed distance from the surface. A prototype measurement system was composed of a transmitting part, a receiving part and a signal processing circuit. The materials of standard measurement which was used in this experiment were SM45C, STS303 and Al60. According to the results of this study, approximation surface roughness formulas which was deduced from the correlation of between the standard surface roughness and the sensing output were verified that they were effect against the surface roughness measurement value of the option sample. And handy optical fiber surface roughness measurement device which was produced by an order was verified that it was effect for measuring of the precision surface roughness.

A Study on the Flow Analysis according to the change of Surface Roughness Gap in the Leisure Ship (레저선박의 표면조도 간격변화에 따른 유동해석에 관한 연구)

  • Oh, Woo-Jun;Cho, Dea-Hwan;Lee, Dong-Sub;Shon, Chang-Bae;Lee, Gyoung-Woo
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.243-244
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    • 2009
  • From large to small vessels of the surface is not smooth. and The surface ship has a surface roughness. Because surface roughness increases the surface resistance and heat transfer, be considered when designing a ship that is an important design factor. Due to surface roughness study on flow around and due to changes in flow and turbulence intensity for the ongoing research is conducted. Roughness of the surface ships from the ship by air as well as machines can be widely applied. In this study, the surface roughness of the leisure marine interval, any change will affect the surface flow, area due to surface roughness for boundary-experimental study was performed.

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Evaluation of surface roughness using phase-measuring interferometer for a few ten ${\AA}$ and sub ${\AA}$-rough substrates (위상측정 간섭계를 이용한 수십 ${\AA}$급 및 sub ${\AA}$급 반사경 기판 조도 평가)

  • 조민식;정태호;오문수
    • Korean Journal of Optics and Photonics
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    • v.10 no.4
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    • pp.283-288
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    • 1999
  • We investigated the characteristics of surface roughness evaluation using phase-measuring interferometer for a few ten $\AA$ and sub $\AA$-rough substrates. The influence of phase averaging and intensity averaging on the roughness measurement by phase measuring interferometer was investigated and the optimal number of phase and intensity averaging for the least measurement error was searched. For a few ten $\AA$-rough sample, roughness value did not depend so much on the data averaging. Whereas, measurement error for sub $\AA$-rough sample was significantly improved as the number of phase and intensity averaging increased. At the phase averaging of 30 and the intensity averaging of 20, roughness value that measurement error was minimized was obtained, and it was in good agreement with that by optical heterodyne interferometer. Roughness measurement at the optimal data averaging showed also good repeatability error less than 0.01$\AA$.

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The Effects of Surface Coating Material for Aluminum Form on Surface Quality of the Concrete (알루미늄 거푸집 표면코팅재가 콘크리트 표면품질에 미치는 영향)

  • Han, Cheon-Goo;Park, Jae-Soon
    • Journal of the Korea Institute of Building Construction
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    • v.10 no.3
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    • pp.57-64
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    • 2010
  • This study is to analyze the effects of aluminum form surface coating material on surface quality of concrete. When observing the surface quality of concrete affected by the change of aluminum form surface coating material, in general, as the number of use of the coating material increased, the surface quality of concrete decreased and good surface quality was shown in plywood (hereinafter PW). For epoxy (hereinafter EP) resin, when applying form remover, good surface quality was shown. For the surface roughness of concrete by the application form oil of form remover and the number of use of the coating material, as the number of use increased, highest surface roughness value was shown which meant the leveling was bad, but the surface roughness value in EP and PW was the lowest. Just for EP, when applying form remover, surface roughness value was low. For the number of void for concrete by the application of form remover and the number of use of the coating material, In general, the number of void which was generated when applying form oil the remover decreased.

Implementation of Roughness-Induced Turbulent Transition Model on Inflight Icing Code (표면 조도를 고려한 난류 천이 모델의 항공기 결빙 해석자에 대한 적용 연구)

  • Min, Seungin;Yee, Kwanjung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.1
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    • pp.23-33
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    • 2020
  • In this study, the effect of surface roughness distribution and its influence on the inflight icing code was investigated. Previous numerical studies focused on the magnitude of surface roughness, and the effects were only addressed in terms of changes in thermal boundary layers with fully turbulent assumption. In addition, the empirical formula was used to take account the turbulent transition due to surface roughness, which was regarded as reducing the accuracy of ice shape prediction. Therefore, in this study, the turbulent transition model based on the two-equation turbulence model was applied to consider the effects of surface roughness. In order to consider the effect of surface roughness, the transport equation for roughness amplification parameter was applied, and the surface roughness distribution model was implemented to consider the physical properties. For validation, the surface roughness, convective heat transfer coefficient, and ice shape were compared with experimental results and other numerical methodology. As a result, it was confirmed that the excessive prediction of the heat transfer coefficient at the leading edge and the ice horn shape at the bottom of the airfoil were improved accordingly.

Analysis of Turbulent Velocity Fluctuations of Rectangular Shape of the Surface Roughness Change (직사각형 형상의 표면조도 변화에 의한 난류변동분 해석)

  • Oh, Dae-Kyun;Oh, Woo-Jun;Kim, Do-Jung;Lee, Gyoung-Woo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.17 no.2
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    • pp.167-172
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    • 2011
  • In physical engineering, the turbulent flow on the surface roughness is very important. With the welding, design and paint, the hull surface roughness at each stage in the various aspects are important factors to be considered. In this study, the hull surface roughness geometry that was generalized to the PIV was applied to the tank test. The roughness of the surface changed the distance of the interval. Experimental velocity is Re = $1.1{\times}10^4$, Re = $2.0{\times}10^4$ and Re = $2.9{\times}10^4$. The turbulent intensity at the time-average were examined The roughness coefficient occurred with increasing turbulence intensities was stronger. The turbulence intensity away from the roughness in the shape was zero. The variation of turbulence intensity at the experimental flow conditions change was not affected.

Experiments on Slip Coefficients of High-Strength Bolt Connection with Weathering Steel (I) (내후성강재 고장력볼트 이음부 미끄럼계수 평가 실험 (I))

  • Park, Yong Myung;Seong, Taek Ryong
    • Journal of Korean Society of Steel Construction
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    • v.12 no.2
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    • pp.167-175
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    • 2000
  • An experimental research to evaluate the slip coefficient of high-strength slip-critical-type bolt connection of weathering steel plate has been performed in this paper. Experiments were performed with several surface conditions such as clean mill scale with hand or power brush cleaning, shot blast cleaned, inorganic zinc primer coated, and weather coated surfaces. Also, the relaxation of bolt clamping force was estimated during 500 hours. It was ascertained from the experiments that slip coefficients are greater than 0.40 in all faying surface conditions except mill scale surface with power brushing. The quantify of relaxation depended on the surface conditions and was $3{\sim}8%$, i.e., less than 10%.

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Experimental Investigation on the Effect of Low-Speed Icing Condition to the Surface Roughness Formation (저속 결빙조건이 표면 조도 형성에 미치는 영향에 관한 실험적 연구)

  • Kang, Yu-Eop;Min, Seungin;Kim, Taeseong;Yee, Kwanjung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.2
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    • pp.99-108
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    • 2020
  • In the field of aircraft icing prediction, surface roughness has been considered as critical factor because it enhances convective heat transfer and changes local collection efficiency. For this significance, experimental studies have been conducted to acquire the quantitative data of the formation process. Meanwhile, these experiments was conducted under low-speed condition due to the measurement difficulties. However, it has not been investigated that how the flow characteristic of low-speed will effects to the surface roughness. Therefore, the present study conducted experiment under low-speed icing condition, and analyzed the relation between surface roughness characteristics and icing condition. As an analysis method, the dominant parameters used in the previous high-speed experiments are employed, and roughness characteristics are compared. The size of roughness element was consistent with the previous known tendency, but not the smooth zone width.