• Title/Summary/Keyword: surface comparison

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A MEASURE OF ROBUST ROTATABILITY FOR SECOND ORDER RESPONSE SURFACE DESIGNS

  • Das, Rabindra Nath;Park, Sung-Hyun
    • Journal of the Korean Statistical Society
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    • v.36 no.4
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    • pp.557-578
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    • 2007
  • In Response Surface Methodology (RSM), rotatability is a natural and highly desirable property. For second order general correlated regression model, the concept of robust rotatability was introduced by Das (1997). In this paper a new measure of robust rotatability for second order response surface designs with correlated errors is developed and illustrated with an example. A comparison is made between the newly developed measure with the previously suggested measure by Das (1999).

A Research regarding the Figuration Comparison of 3D Printing using the Radiation DICOM Images (방사선 DICOM 영상을 이용한 3차원 프린팅 출력물의 형상 비교에 관한 연구)

  • Kim, Hyeong-Gyun;Choi, Jun-Gu;Kim, Gha-Jung
    • The Journal of the Korea Contents Association
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    • v.16 no.2
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    • pp.558-565
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    • 2016
  • Recent 3D printing technology has been grafting onto various medical practices. In light of this trend, this research is intended to examine the figuration surface's accuracy of 3D images made by using DICOM images after printing by 3D printing. The medical images were obtained from animal bone objects, while the objects were printed after undergoing STL file conversion for 3D printing purposes. Ultimately, after the 3D figuration, which was obtained by the original animal bones and 3D printing, was scanned by 3D scanner, 3D modeling was merged each other and the differences were compared. The result analysis was conducted by visual figuration comparison, color comparison of modeling's scale value, and numerical figuration comparison. The shape surface was not visually distinguished; the numerical figuration comparison was made from the values measured from the four different points on the X, Y and Z coordinates. The shape surface of the merged modeling was smaller than the original object (the animal bone) by average of -0.49 mm in the 3D printed figuration. However, not all of the shape surface was uniformly reduced in size and the differences was within range of -0.83 mm on the experiment.

Expansion of Terzaghi Arching Formula to Consider an Arbitrarily Inclined Sliding Surface and Examination of its Effect

  • Son, Moorak
    • Journal of the Korean GEO-environmental Society
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    • v.17 no.7
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    • pp.27-33
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    • 2016
  • This study expanded Terzaghi arching formula, which assumed a vertical surface as a sliding surface, to consider an arbitrarily inclined surface as a sliding surface and examined the effect of a sliding surface. This study firstly developed a formula to expand the existing Terzaghi arching formula to consider an inclined surface as well as a vertical surface as a sliding surface under the downward movement of a trap door. Using the expanded formula, the effect of excavation, ground, and surcharge conditions on a vertical stress was examined and the results were compared with them from Terzaghi arching formula. The comparison indicated that the induced vertical stress was highly affected by the angle of an inclined sliding surface and the degree of influence depended on the excavation, ground, and surcharge conditions. It is expected that the results from this study would provide a better understanding of various arching phenomenon in the future.

Size-dependent analysis of functionally graded ultra-thin films

  • Shaat, M.;Mahmoud, F.F.;Alshorbagy, A.E.;Alieldin, S.S.;Meletis, E.I.
    • Structural Engineering and Mechanics
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    • v.44 no.4
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    • pp.431-448
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    • 2012
  • In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

Comparison of Heat Transfer and Pressure Drop Characteristics of Heat Exchangers Having Plain Fins Under Dry and Wet Conditions

  • Kim Nae-Hyun;Sin Tae-Ryong;Lee Eung-Ryul
    • International Journal of Air-Conditioning and Refrigeration
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    • v.13 no.3
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    • pp.128-137
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    • 2005
  • In this study, dry and wet surface pressure drop and heat transfer characteristics of heat exchangers having plain fins were investigated. Nine samples having different fin pitches and rows were tested. The wet surface heat transfer coefficient was reduced from experimental data using enthalpy-potential method. The wet surface heat transfer coefficients were approximately equal to the dry surface values except for one row configuration. For one row configuration, the wet surface heat transfer coefficients were approximately $30\%$ lower than the dry surface values. For the pressure drop, the wet surface yielded approximately $30\%$ higher values compared with the dry surface counterpart. Data were compared with existing correlations.

Comparison study of nanosecond laser induced wet and dry ablation of PMMA (나노초 레이저를 이용한 PMMA의 습식 및 건식어블레이션 비교 연구)

  • lee, Ho
    • Journal of the Korean Society of Industry Convergence
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    • v.22 no.3
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    • pp.243-250
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    • 2019
  • The nanosecond laser assisted ablation have been investigated. The biocompatable polymer PMMA was employed as the target material and the two distinctive surface conditions were test. The first surface condition is a dry surface for which the target surface is exposed to air and the second surface condition is the wet surface for which the target surface is covered with dehydrated water. The ablation volume, the laser induced acoustic wave, the laser induced plasma were investigated for both wet and dry condition. The nanosecond laser pulse ablatied more on the wet surface compared to the dry surface. The enhanced ablation of wet surface is attributed to the confined acoustic wave and the laser-induced plasma in the liquid layer.