• Title/Summary/Keyword: Surface

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Machined Surface Inspection Based on Surface Fairing on the Machine Tool (곡면평활화를 고려한 공작기계상에서의 가공곡면 검사)

  • Lee, Se-Bok;Kim, Gyeong-Don;Jeong, Seong-Jong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4 s.175
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    • pp.937-945
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    • 2000
  • The assessment of machined surface is difficult because the freeform surface must be evaluated by surface fairness as well as dimensional accuracy. In this study, the machined freeform surface is modeled by interpolating the data measured on the machine tool into the mathematical continuous surface, and then the surface model is improved with the parameterization to minimize surface fairness. The accuracy reliability of the measured data is confirmed through compensation of volumetric errors of the machine tool and of probing errors. Non-uniform B-spline surface interpolation method is adopted to guarantee the continuity of surface model. Surface fairness is evaluated with the consideration of normal curvature on the interpolated surface. The validity and usefulness of the proposed method is examined through computer simulation and experiment on the machine tool.

Effect of Surface Charge in Hydrophobicity of Insulating Material and Decay of Surface Voltage after Corona Charging

  • Huh, Chang-Su;Youn, Bok-Hee;Seo, You-Jin;Hwang, Sun-Mook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05e
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    • pp.1-5
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    • 2003
  • This paper presented the effects of accumulation of surface charges on hydrophobicity level and the surface states of silicone polymer used for outdoor insulator treated by ultraviolet irradiation and corona discharge through measuring surface voltage decay of a corona-charged specimen were investigated. The surface resistivity by the method of the surface potential decay was compared with the value by the three electrodes methods. From this study, it was found that the accumulation of surface charges above a critical surface voltage on silicone insulating materials could lead to the temporary loss of surface hydrophobicity. In addtion, uv stress lead to a longer decay time of surface charges. We could conclude that the effects of surface charges on hydrophocity level and the changes of surface state by various artificial treatments were understood through a trend of surface potential decay.

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A Study on the Thermal Performance of Embossing Surface Sandwich Panel

  • Son, Cheol-Soo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.9 no.2
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    • pp.69-76
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    • 2001
  • The purpose of this research is to investigate the thermal performance of embossing surface sandwich panel and flat surface sandwich panel. To do this research, thermal performances in summer season at the six points of embossing surface sandwich panel and flat surface sandwich panel are investigated focusing on the temperature. Three kinds of embossing surface sandwich panel and one kind of flat surface sandwich panel are used for this research. At the same size of sandwich panel, the average temperature differences of flat surface sandwich panel between average temperature at the 0.5 mm below copper plate and average outside air temperature and surface temperature are higher than those of embossing surface sandwich panel. The average heat transfer rate of flat surface sandwich panel in higher than that of embossing surface sandwich panel. More study will be needed about the size of diameter and height of embossing, and materials of embossing surface sandwich panel.

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A Study on the Thermal Performance of Embossing Surface Sandwich Panel During the Summer (여름철 엠보싱 샌드위치 패널의 열적 성능에 관한 연구 -평판 샌드위치 패널과 비교를 중심으로-)

  • 손철수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.10
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    • pp.917-924
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    • 2000
  • The purpose of this research is to investigate the thermal performance of embossing surface sandwich panel and flat surface sandwich panel during the summer. To do this research, thermal performances in summer season at the six points of embossing surface sandwich panel and flat surface sandwich panel are investigated focusing on the temperature. Three kinds of embossing surface sandwich panel and one kind of flat surface sandwich panel are used for this research. At the same size of sandwich panel, the average temperature differences of flat surface sandwich panel between average temperature at the 0.5 mm below copper plate and average outside air temperature and surface temperature are higher than those of embossing surface sandwich panel. The average heat transfer rate of flat surface sandwich panel is higher than that of embossing surface sandwich panel. More study will be needed about the size of diameter and height of embossing, and materials of embossing surface sandwich panel.

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EFFECTS OF VARIOUS SURFACE TREATMENTS FOR TITANIUM ON SURFACE MICRO ROUGHNESS, STATIC WETTABILITY, FIBRONECTIN ADSORPTION (표면 처리 방법에 따른 타이타늄의 미세 표면 거칠기, 표면 젖음성, fibronectin 흡착량에 미치는 영향)

  • Shin Hwa-Sub;Kim Young-Su;Shin Sang-Wan
    • The Journal of Korean Academy of Prosthodontics
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    • v.44 no.4
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    • pp.443-454
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    • 2006
  • Purpose: This study aims to get the fundamental data which is necessary to the development direction of implant surface treatment hereafter, based on the understanding the surface structure and properties of titanium which is suitable for the absorption of initial tissue fluid by researching effects of additional surface treatments fir sandblasted with large git and acid-etched(SLA) titanium on surface micro-roughness, static wettability, fibronectin adsorption Materials and Method: In the Control groups, the commercial pure titanium disks which is 10mm in diameter and 2mm in thickness were treated with HCI after sandblasting with 50$\mu$m $Al_2O_3$. The experiment groups were made an experiment each by being treated with 1) 22.5% nitric acid according to SLA+ASTM F86 protocol, 2) SLA+30% peroxide, 3) SLA+NaOH, 4) SLA+ Oxalic acid, and 5) SLA+600$^{\circ}C$ heating. In each group, the value of Ra and RMS which are the gauges of surface roughness was measured, surface wettability was measured by analyzing with Sessile drop method, and fibronectin adsorption was measured with immunological assay. The significance of each group was verified by (SPSS, ver.10.0 SPSS Inc.) Kruskal-Wallis Test. (α=0.05) And the correlation significance between Surface micro-roughness and surface wettability. surface roughness and fibronectin adsorption, and surface wettability and fibronectin adsorption was tested by Spearman's correlation analysis. Result: All measure groups showed the significant differences in surface micro-roughness, surface wettability, and fibronectin adsorption. (p<0.05) There was no significance in correlation among the surface micro-roughness, surface wettability, and fibronectin adsorption. (p>0.05) Conclusion: Surface micro-roughness and surface wettability rarely affected the absorption of initial tissue fluid on the surface of titanium.

Effects of Surface Depression on Pool Convection and Oscillation in GTAW (GTA 용접에서 용융풀의 표면 변형이 유동과 진동에 미치는 영향)

  • 고성훈;최상균;유중돈
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.70-77
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    • 1999
  • Surface depression in the arc welding is calculated numerically to analyze its influence on pool convection and oscillation. The magnitude of surface depression due to arc pressure on the stationary GTA pool surface is relatively small, and fluctuations of the surface and velocity are caused mainly by arc pressure. The inward flow on the surface due to the electromagnetic force and positive surface tension gradient acts to decrease surface depression. Surface depression appears to have minor effects on average flow velocity and thus pool geometry. Pool oscillation occurs due to surface vibration, and oscillation frequencies are affected mainly by the surface tension and pool width. The input parameters such as arc pressure and current have negligible effects on the oscillation frequency, and the surface tension gradient has limited effects. Since the oscillation frequency varies slightly according to penetration, pool oscillation for the partial penetration weld pool is applicable to monitor the pool width.

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An effect of load on surface roughness in surface rolling (표면 Rolling시 가압력이 표면 조도에 미치는 영향)

  • 강명순
    • Journal of the korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.57-65
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    • 1987
  • The surface rolling method which is one of the plastic deformation processes increases the surface roughness with reduction of diameter and hardness. In this study, three NACHI 6000 ZZ bearing were used for surface rolling tool on a mild steel The following results have been obtained with the mild steel. 1) The load is major factor in getting fine surface roughness of roller finishing after grinding The optimal surface roughness of SS41 steel can be obtained at the contact pressure of 210 kgf/cm$^{2}$. 2) At the contact pressure range of 200kgf/cm$^{2}$-210kgf/cm$^{2}$ for optimal surface roughness, The surface hardness increased to Hv200-Hv240 from Hv 125 before surface rolling. 3) Within the diameter variation of 13 .mu.m the surface roughness and the surface hardness were increased, but out of variation of 14.mu.m. The surface roughness become worse and the surface hardness was increased.

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Surface Properties and interfacial Potential Distribution of Surface Treated-Alumina (표면처리한 알루미나의 표면물성과 계면전위분포)

  • 홍영호;함영민
    • Journal of the Korean Ceramic Society
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    • v.33 no.7
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    • pp.823-831
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    • 1996
  • Due to the intrinsic low surface activation of ${\gamma}$-alumina it has been used limitely in practice. Accordingly forward enhancing its utility ${\gamma}$-alumina surface was treated with slfuricf aicd nitric acid and chloric acid respec-tively. Subsequently the effects of surface activity on the surface electrical characteristics were investigated. The ${\gamma}$-alumina was prepared by the precipitation of aluminium nitrate [Al(NO3)3.9H2O] using ammonia water as a precipitator and it was chemically treated with such acids mentioned above. The surface and morphology of the acid-treated ${\gamma}$-alumina were analysed by XRD, BET and the surface activities were measured by the amine titration methods. The interfacial properties of the ${\gamma}$-alumina dispersed in electrolyte solution were esti-mated by the surface charge density measured using potentiometric tiration. Based on the relation between surface charge density and the acid amount the following results were drawn for the surface and interfacial electrical properties ; Acidic properties of surface-treated alumina increase with anion load on alumina surface. P. Z. C decreases with acid amount on alumina surface. The surface charge densities were apart from electrolyte ionic strength. The acidity of ${\gamma}$-alumina is linearly dependent on the P. Z,.C when the ${\gamma}$-alumina was dispersed in aqueous electrolyte solution.

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Investigation on the Description Method of Extrusion Die Surface using NURBS Surface Scheme (NURBS 곡면기법을 이용한 압출금형 곡면의 표현방법에 관한 연구)

  • 유동진;임종훈
    • Transactions of Materials Processing
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    • v.12 no.2
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    • pp.151-160
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    • 2003
  • In the present study, an advanced surface construction method based on NURBS surface scheme is proposed to construct the extrusion die surface. The inlet and outlet profiles we precisely described with NURBS curves using the cubic appropriate control points and weights. The interior control Points of surface are generated using the cubic interpolation of the weights at the inlet and outlet sections. In order to verify of the proposed method, automatic surface generation is carried out for the various types of extrusion die surface.

An effect of load on surface roughness in surface rolling (표면 로울링시 가압력이 표면 조도에 미치는 영향)

  • 강명순;김희남
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.6
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    • pp.935-944
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    • 1987
  • The surface rolling, one of the plastic working processes, provides good surface roughness with the reduction of diameter and the increase of surface hardness. In this study three Nachi 6000ZZ bearing were used for surface rolling on ductile cast iron. The results obtained are as follows; (1) The good surface roughness can be obtained with roller surface radius of curvature of 24mm after the 2nd rolling. (2) The surface roughness of ductile cast iron was 0.48.mu.mRmax by the contact pressure of 140kgf/mm$^{2}$ and surface hardness was Hv 395 with roller surface radius of curvature of 24mm after the 2nd rolling. (3) The reduction of specimen diameter of ductile cast iron were -12.8.mu.m due to rolling. (4) Within the diameter variation of -11.mu.m, surface roughness and surface hardness were increased, but at the range of exceeding -14.mu.m of the diameter variation the surface roughness became worse and the surface roughness became worse and the surface hardness was increased. (5) Dynamic contact area was about 25% to 30% of static contact area. The calculated contact pressure showed a good agreement with the experimental contact pressure.