• Title/Summary/Keyword: Surface profile measurement

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Free-Stream Turbulence Effect on the Heat (Mass) Transfer Characteristics on a Turbine Rotor Surface (자유유동 난류강도가 터빈 동익 표면에서의 열(물질)전달 특성에 미치는 영향)

  • Lee, Sang-Woo;Park, Jin-Jae;Kwon, Hyun-Goo;Park, Byung-Kyu
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1442-1446
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    • 2004
  • The heat (mass) transfer characteristics on the blade surface of a first-stage turbine rotor cascade has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is employed for the measurements of the local heat (mass) transfer coefficient on the curved blade surface. The experiments are carried out for two free-stream turbulence intensities of 1.2% and 14.7%. The high free-stream turbulence results in more uniform distributions of heat load on the both pressure and suction surfaces and in an early boundary-layer separation on the suction surface. The heat (mass) transfer enhancement on the suction surface due to the endwall vortices is found to be relatively small under the high free-stream turbulence.

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Noncontact Type Three Dimensional Profile Measurement for CAD Modeling of Sculptured Surface (자유곡면의 CAD 모델링을 위한 비접촉식 삼차원 형상측정)

  • Park, H.G.;Park, Y.B.;Kim, S.W.
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.1
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    • pp.5-14
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    • 1995
  • An optical measurement method of three dimensional surface profiles which is named the slit beam projection is suggested and practically implemented. This method is intended especially for noncontact and fast digitization of sculptured surfaces for CAD modeling and die manufacturing. Its basic principles are based on geometric optics. Deatiled optical principles and an sub-pixel image processing technique to enhance the measuring resolutions are described in this study. The measuring performances of the slit beam projection are presented and discussed to demonstrate that an actual measuring accuracy of below .+-. 0.2mm can be achived over the whole measuring range(500mm*300mm*200mm)

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Non-contact critical current measurement of superconducting coated conductor using Hall Probe (Hall Probe를 이용한 초전도선재의 비접촉 임계전류 측정 방법)

  • Kim, Ho-Sup;Oh, Sang-Soo;Lee, Nam-Jin;Ha, Dong-Woo;Baik, Seung-Kyu;Ko, Rock-Kil;Ha, Hong-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.12-12
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    • 2010
  • The hall probe measurement system was used to measure the critical current distribution of superconducting coated conductor. The system consists of reel to reel moving apparatus, 7 array hall probe, a rotary encoder and permanent magnet. The magnetic field profile across the width of superconducting coated conductor using Bean's critical state model was calculated. The effect of various parameters of the formulas on the magnetic field distribution and the effect of shape and size of artificial defects, which were formed on the surface of SmBa2Cu3O7-d(SmBCO) coated conductor using laser marking system, on the hall probe magnetic field signal of the hall probe measurement system was investigated.

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A Study on Measurement for Endmill Dia. using Electric Contact Method (공구마모보정을 위한 전기접점식 자동공구 보정시스템 개발)

  • 정상화;신형성;나윤철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.445-449
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    • 2001
  • The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. In this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

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Finite Element Analysis for Prediction of Residual Stresses Induced by Shot Peening (쇼트피닝 잔류응력 예측을 위한 유한요소해석)

  • Kim, Cheol;Yang, Won-Ho;Sung, Ki-Deug;Ko, Myung-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.1
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    • pp.198-204
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    • 2001
  • The shot peening is largely used for a surface treatment of metallic components where small spherical pellets called shots are blasted onto the surface with velocities up to 100 m/s. This treatment leads to improvement of fatigue behavior due to the developed compressive residual stresses, and so it has gained widespread acceptance I the automobile and aerospace industries. The residual stress profile on surface layer depends on the parameters of shot peening, which are, shot velocity, shot diameter, coverage, impact angle, material properties etc. and the method to confirm this profile is the measurement by X-ray diffractometer only. Despite the importance to automobile ad aerospace industries, little attention has been devoted to the accurate modelling of the process. In this paper, the simulation technique is applied to predict the magnitude ad distribution of the residual stress and plastic deformation caused by shot peening with the help of the finite element analysis.

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The Finite Element Analysis for Prediction of Residual Stresses Induced by Shot Peening (쇼트피닝 잔류응력 예측을 위한 유한요소해석)

  • Kim, Cheol;Yang, Won-Ho;Sung, Ki-Deug;Cho, Myoung-Rae;Ko, Myung-Hoon
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.218-223
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    • 2000
  • The shot peening is largely used for a surface treatment in which small spherical parts called shots are blasted on a surface of a metallic components with velocities up to 100m/s. This treatment leads to an improvement of fatigue behavior due to the developed compressive residual stresses, and so it has gained widespread acceptance in the automobile and aerospace industries. The residual stress profile on surface layer depends on the parameters of shot peening, which are, shot velocity, shot diameter, coverage, impact angle, material properties etc. and the method to confirm this profile is only measurement by X-ray diffractometer. Despite its importance to automobile and aerospace industries, little attention has been devoted to the accurate modelling of the process. In this paper, the simulation technique is applied to predict the magnitude and distribution of the residual stress and plastic deformation caused by shot peening with the help of the finite element analysis.

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Quadratic Parabolic Equation to Estimate the Vertical Velocity Distribution in the Natural Streamflow (자연하천의 연직방향 유속분포 추정을 위한 포물선식)

  • Park, Seung-Gi;Kim, Tae-Cheol
    • Journal of Korea Water Resources Association
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    • v.33 no.2
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    • pp.169-179
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    • 2000
  • The study was carried out to investigate the characteristics of vertical velocity distribution measured by current meter at Kangkyung station in Keum river during the period of 1995 to 1997. It suggests the quadratic parabola equation to estimate the vertical velocity profile only from the measurement data of surface velocity. The equation was found to be statistically very stable and showed high significance to express the surface velocity and bottom velocity. The vertical velocity profile was detennined by the relationships to the surface velocity, and a coefficient of the quadratic parabolic equation. The equation was verified to the reserved survey data, and the results were confirmed to be good for the estimation of the characteristics of the vertical velocity distribution. The vertical velocity profile can be applied to calculating the mean velocity and discharge, and to analyse the dispersion of pollutant materials in the streamflow.

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Analysis on the Langmuir adsorption isotherm at the $Pt/H_2SO_4$ electrolyte interface using the ac impedance measurement and phase-shift method ($Pt/H_2SO_4$ 전해질 계면에서 교류임피던스 측정과 위상이동 방법에 의한 Langmuir 흡착등온식 해석)

  • Chun Jang Ho;Cho Sung Chil;Son Kwang Chul
    • Journal of the Korean Electrochemical Society
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    • v.2 no.1
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    • pp.23-26
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    • 1999
  • The Langmuir adsorption isotherm at the $(Pt)/0.1M\;H_2SO_4$ electrolyte interface has been qualitatively analyzed using the ac impedance measurement and phase-shift method. The phase shift $(\phi)$ depends on both the cathode potential (E<0) and frequency (f) and is inversely proportional to the factional surface coverage $(\theta)$. At an intermediate frequency band (ca. $1\~100$ Hz), the phase-shift profile $(\phi\;vs.\;E)$ can be related to the fractional surface coverage $(\theta\;vs.\;E)$. The phase-shift profile $(\phi\;vs.\;E)$ can be used as an experimental method to estimate and analyze the Langmuir adsorption isotherm $(\theta\;vs.\;E)$. The equilibrium constant (K) and the standard free energy $({\Delta}G_{ads})$ of the adsorbed hydrogen atom $(H_{ads})\;and\;3\times10^{-4}$ and 20.1 kJ/mol, respectively.

Tribological Properties of Annealed Diamond-like Carbon Film Synthesized by RF PECVD Method

  • Choi, Won-Seok
    • Transactions on Electrical and Electronic Materials
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    • v.7 no.3
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    • pp.118-122
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    • 2006
  • Diamond-like carbon (DLC) films were prepared on silicon substrates by the RF PECVD (Plasma Enhanced Chemical Vapor Deposition) method using methane $(CH_4)$ and hydrogen $(H_2)$ gas. We examined the effects of the post annealing temperature on the tribological properties of the DLC films using friction force microscopy (FFM). The films were annealed at various temperatures ranging from 300 to $900^{\circ}C$ in steps of $200^{\circ}C$ using RTA equipment in nitrogen ambient. The thickness of the film was observed by scanning electron microscopy (SEM) and surface profile analysis. The surface morphology and surface energy of the films were examined using atomic force microscopy and contact angle measurement, respectively. The hardness of the DLC film was measured as a function of the post annealing temperature using a nano-indenter. The tribological characteristics were investigated by atomic force microscopy in FFM mode.

The necessary number of profile lines for the analysis of concrete fracture surfaces

  • Konkol, Janusz;Prokopski, Grzegorz
    • Structural Engineering and Mechanics
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    • v.25 no.5
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    • pp.565-576
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    • 2007
  • The article describes a technique for the measurement of the level of complexity of fracture surfaces by the method of vertical sections, and a performed statistical analysis of the effect of profile lines on the fractographic and fractal parameters of fractures, i.e. the profile line development factor, $R_L$, and the fracture surface development factor, $R_S$, (as defined by the cycloid method), as well as the fractal dimension, $D_C$, (as determined by the chord method), and the fractal dimension, $D_{BC}$, (as determined by the box method). The above-mentioned parameters were determined for fracture surfaces of basalt and gravel concretes, respectively, which had previously been subjected to fracture toughness tests. The concretes were made from mixtures of a water/cement ratio ranging from 0.41 to 0.61 and with a variable fraction of coarse aggregate to fine aggregate, $C_{agg.}/F_{agg.}$, in the range from 1.5 to 3.5. Basalt and gravel aggregate of a fraction to maximum 16 mm were used to the tests. Based on the performed analysis it has been established that the necessary number of concrete fracture profile lines, which assures the reliability of obtained testing results, should amount to 12.