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  • Title/Summary/Keyword: Geometrical Characteristics

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Geometric Characteristics of Landslides on Natural Terrain according to the Geological Condition (지질조건에 따른 자연사면 산사태의 기하학적 특성)

  • Kim, Kyeong-Su;Song, Young-Suk;Chae, Byung-Gon;Cho, Yong-Chan;Lee, Choon-Oh
    • The Journal of Engineering Geology
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    • v.17 no.1 s.50
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    • pp.75-87
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    • 2007
  • The recognitions of geometrical characteristics and occurrence conditions are very important to evaluate the land-slides in natural terrains. In this paper, the geometrical characteristics of landslides are analyzed according to a geo-logical condition in three landslides areas. The three landslides areas are classified to the geological condition. The three landslides areas are Jangheung, Sangju and Pohang. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. During a heavy rainfall of 150588mm in these areas, 1,582 landslides have occurred in 1998. The geometrical characteristics according to the geological condition analyzed from the investigation of these landslides. The frequency of landslide is high exceedingly above 90% of a slope attitude, while the frequency is very low below 70%. The frequency of landslide is high exceedingly between 26 and 30 of slope angle, while the frequency is very low below 20. The size of the landslides is ranged from several tens to several hundreds The length is ranged from 5 m to 300 m, and the width is ranged from 3 m to 50 m. Also, the depth is less than 1 m. Therefore, the landslides in these areas have small width, long length and shallow depth. The type of the landslides is changed from transitional slide at the scarp to debris flow at the low part of slope.

A Study on the Buckling Characteristics of Double-Layer Latticed Domes whose Boundary Configuration are Elliptical (경계부 형상이 타원형인 복층 래티스 돔의 좌굴 특성에 관한 연구)

  • Seo, Young-Ill;Kwun, Ik-No;Kwun, Taek-Jin
    • Journal of Korean Association for Spatial Structures
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    • v.2 no.3 s.5
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    • pp.71-79
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    • 2002
  • The purpose of this paper is to study the buckling characteristics of elliptical latticed domes under conservative loading conditions. The latticed domes are usually designed in geometrically spherical shape. For this type of latticed domes, many researchers have researched and even the simplified estimation codes for the buckling load level have been available. However, geometrically elliptical latticed domes have been often constructed, and show different buckling characteristics following with geometrical parameters as rise-to-span ratio and so on. Therefore, it is necessary to investigate the general tendency of buckling characteristics of the elliptical latticed domes. In this paper, to find out some buckling characteristics of elliptical latticed domes, height, boundary configuration and gap are used as the shape coefficients. For each model with different parameters, the eigen values and the buckling loads are evaluated.

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A Study on Pressure Ripple Characteristics in Bent-Axis Type Oil Hydraulic Piston Pump (사축식 유압 피스톤 펌프의 압력 맥동 특성에 관한 연구)

  • Cho, I.S.;Shin, C.G.;Jung, J.Y.
    • Tribology and Lubricants
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    • v.27 no.4
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    • pp.218-223
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    • 2011
  • To improve the performance of a bent-axis type axial piston pump driven by the tapered pistons, it is necessary to know the pressure ripple characteristics. The purpose of this paper is to understand the effect on the pressure ripple characteristics and the prediction by comparing experimental and theoretical results. The simulation model of the bent-axis type axial piston pump is developed in the AMESim environment using the geometrical dimension and the driving mechanism of the piston pump. The results can be obtained to predict the performance characteristics of the bent-axis type axial piston pump.

A study on the Effect of Section Shape and L/B ratio on the Performance of Planing Hull Type High Speed Fishing Vessel (활주선형 고속어선의 단면형상 및 장-폭비와 성능과의 관계에 대한 연구)

  • Lee, Kwi-Joo;Lee, Kwang-Il
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.34 no.3
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    • pp.283-286
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    • 1998
  • For the systematic study on the resistance characteristics of the planing hull, the experimental studies on the correlation between geometrical characteristics of the subject hull forms and their hydrodynamic characteristics are carried out. This study is the first stage to develop the advanced planing hull type fishing boat and involves the followings; -Resistance characteristics for typical four different section types, -Resistance characteristics for different length-beam ratio

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Analysis on Glass-Bead Type Retroreflector's Optical Characteristics (유리구슬형 재귀반사기의 광학적 특성 해석)

  • Lee, E.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.4
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    • pp.165-173
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    • 1994
  • Retroreflector is different from other reflecting surfaces as it mades reflection in which radiation is returned in directions close to its incoming direction. Because of this characteristics, retroreflectors find many applications in traffic safety related areas. Retroreflectors are usually made using comer cubes, or partially coated glass beads. These glass beads can be made very small, so that they can be coated on sheets or mixed with paints. The design of glass type retroreflector depends on glass bead's shape and material, and its optical characteristics are related to the refractive index of glass. In this paper, a method of anlyzing glass bead type retroreflector's sptical characteristics with respect to shape and optica property of the glass, is presented. First, the coefficient of retroreflection, which is a measure of retroreflector's optical characteristics, is derived analytically using geometrical optics method. And the result is plotted using numerical methods. The results show good match with those obtained experimentally, which were supplied from a commercial retroreflector manufacturer.

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Development of Swirl Disc Nozzles for Knapsack Sprayers (배부식 방제기를 위한 디스크형 노즐 개발)

  • Gwak H.H.;Kim Y.J.;Rhee J.Y.
    • Journal of Biosystems Engineering
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    • v.31 no.3 s.116
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    • pp.153-160
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    • 2006
  • This study was performed to evaluate some geometrical characteristics of disc type swirl nozzles and to develop nozzles having improved spraying performance for knapsack sprayers. Considered geometrical characteristics of the nozzles were disc thickness, orifice diameter, swirl chamber diameter and shape of the swirl chamber (nozzle chamber). 3 types of nozzle cores were compared. Main results of this study were as follows. 1. Spraying angle (A) was increased with decreasing disc thickness (x), and with increasing orifice diameter (y) or spraying pressure (z). The equation was as a follow. A=3.951x+73.50y+18.97z60.16 2. Spraying flow rate (F) was increased with decreasing disc thickness (x), and with increasing orifice diameter (y) or spraying pressure (z). The equation was as a follow. F=89.95x+611.09y+620.49z868.20 3. Mean spraying droplet size (V) was decreased with decreasing disc thickness (x), with increasing orifice diameter (y) in low spraying pressure, with decreasing orifice diameter (y) in high spraying pressure, and with increasing spraying pressure (z). V=148.77x4746.85x3+1311.76x2917.31x 4. The spray pattern was compared using CV values. The CV value of the nozzle core type 1 was 26.7% in spraying pressure 3kgf/cm2, the CV value of the core type 2 was 23.6% in spraying pressure 2kgf/cm2, the CV value of the core type 3 was 20.6% in spraying pressure 1kgf/cm2. 5. Minimum spraying pressure was improved from 1.5kgf/cm2to1.0kgf/cm2 by changes of nozzle core shape.

On the dynamic behavior of functionally graded cracked beams resting on winkler foundation under moving load

  • Alaa A. Abdelrahman;Mohamed Ashry;Amal E. Alshorbagy;Mohamed A. Eltaher;Waleed S. Abdalla
    • Steel and Composite Structures
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    • v.53 no.2
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    • pp.169-194
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    • 2024
  • Although the excellent characteristics of functionally graded materials (FGMs) cracks could be found due to manufacturing defects or extreme working conditions. The existence of these cracks may threaten the material or structural strength, reliability, and lifetime. Due to high cost and restrictions offered by practical operational features these cracked components couldn't be replaced immediately. Such circumstances lead to the requirement of assessing the dynamic performance of cracked functionally graded structural components especially under moving objects. The present study aims to comprehensively investigate the dynamic behavior of functionally graded cracked Timoshenko beams (FGCTBs) resting on Winkler foundation and subjected to moving load through shear locking free finite elements methodology. The through thickness material distribution is simulated by the exponential gradation law. The geometric discontinuity due to cracks is represented using the massless rotational spring approach. The shear locking phenomena is avoided by using the different interpolation functions orders for both deflections and rotations. Based on Timoshenko beam element, a shear locking free finite elements methodology is developed. The unconditionally stable Newmark procedure is employed to solve the forced vibration problem. Accuracy of the developed procedure is verified by comparing the obtained results with the available results and an excellent agreement is found. Parametric studies are conducted to explore effects of the geometrical, material characteristics, crack geometrical characteristics, the elastic foundation parameter, and the moving load speed on the dynamic behavior for different boundary conditions. Obtained results revealed the significant effect these parameters on the dynamic performance of FGCTBs.

Pattern Development of Waist / Abdominal Area of Obese Womem Using 3D Geometrical Model (3D모델을 이용한 비만체형 여성의 허리-배 부위 패턴 특성 연구)

  • Kim, So-Young;Hong, Kyung-Hi
    • Journal of the Korean Society of Clothing and Textiles
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    • v.29 no.7 s.144
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    • pp.1018-1026
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    • 2005
  • Recent development of 3D scanner and software is regarded as a promising method of acquiring replicas from human body indirectly. It would be very helpful if we could predict the characteristics of 2D pattern from the simple parameters related to 3D shape for ordinary user. Therefore, in this study, investigation of 2D pattern of waist/abdominal area from the 3D geometrical model was conducted for the pattern development of waist nipper. To create body models and develop the surface of them, one ortho commonly used CAD/CAM program, IDEAS(UGS-plm solutions, USA) was used. As for the size of the models, the width, thickness, and circumference ranges of adult women's torso reported in National Anthropometric Survey of Korea (1997) were used as a standard model. Seven size variations were made by changing the width of the waist only, from 19 cm to 40 cm. Therefore, simulated body models include not only the normal body but also obese body who has wider waist and abdomen width than hip width. As results, it was found that the curvature of the unfolded 2D pattern around the abdominal area decreases as the waist width increases. As the width of the waist increases more and more, so that the comparative ratios around the torso becomes in abnormal ranges, there appears inflection points and the direction of curvature was changed. 2D Patterns obtained in this research were quantified by curvature, length of the curve and angle of deflection in the reference frame box for the convenience of the actual pattern making process. It was also possible to find that the shape of patterns of abnormal body resulted in a quite interesting change in the curves of 2D pattern, which could be applied to the custom made waist nipper for obese women.

Comprehensive evaluation of structural geometrical nonlinear solution techniques Part II: Comparing efficiencies of the methods

  • Rezaiee-Pajand, M.;Ghalishooyan, M.;Salehi-Ahmadabad, M.
    • Structural Engineering and Mechanics
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    • v.48 no.6
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    • pp.879-914
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    • 2013
  • In part I of the article, formulation and characteristics of the several well-known structural geometrical nonlinear solution techniques were studied. In the present paper, the efficiencies and capabilities of residual load minimization, normal plane, updated normal plane, cylindrical arc length, work control, residual displacement minimization, generalized displacement control and modified normal flow will be evaluated. To achieve this goal, a comprehensive comparison of these solution methods will be performed. Due to limit page of the article, only the findings of 17 numerical problems, including 2-D and 3-D trusses, 2-D and 3-D frames, and shells, will be presented. Performance of the solution strategies will be considered by doing more than 12500 nonlinear analyses, and conclusions will be drawn based on the outcomes. Most of the mentioned structures have complex nonlinear behavior, including load limit and snap-back points. In this investigation, criteria like number of diverged and complete analyses, the ability of passing load limit and snap-back points, the total number of steps and analysis iterations, the analysis running time and divergence points will be examined. Numerical properties of each problem, like, maximum allowed iteration, divergence tolerance, maximum and minimum size of the load factor, load increment changes and the target point will be selected in such a way that comparison result to be highly reliable. Following this, capabilities and deficiencies of each solution technique will be surveyed in comparison with the other ones, and superior solution schemes will be introduced.

Geometrical Design and SLIPS Lubrication for Enhancement of Negative-pressure-driven Internal Flow Rate in Metal Pipes (금속관 내부의 음압유량 향상을 위한 기하학적 디자인 및 SLIPS 윤활)

  • Kim, Dong Geun;Jang, Changhwan;Kim, Seong Jae;Kim, Daegyoum;Kim, Sanha
    • Tribology and Lubricants
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    • v.37 no.6
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    • pp.253-260
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    • 2021
  • Metal pipes are used in a wide range of applications, from plumbing systems of large construction sites to small devices such as medical tools. When a liquid is enforced to flow through a metal pipe, a higher flow rate is beneficial for higher efficiency. Using high pressures can enhance the flow rate yet can be harmful for medical applications. Thus, we consider an optimal geometrical design to increase the flow rate in medical devices. In this study, we focus on cannulas, which are widely used small metal pipes for surgical procedures, such as liposuction. We characterize the internal flow rate driven by a negative pressure and explore its dependence on the key design parameters. We quantitatively analyze the suction characteristics for each design variable by conducting computational fluid dynamics simulations. In addition, we build a suction performance measurement system which enables the translational motion of cannulas with pre-programmed velocity for experimental validation. The inner diameter, section geometry, and hole configuration are the design factors to be evaluated. The effect of the inner diameter dominates over that of section geometry and hole configuration. In addition, the circular tube shape provides the maximum flow rate among the elliptical geometries. Once the flow rate exceeds a critical value, the rate becomes independent of the number and width of the suction holes. Finally, we introduce a slippery liquid-infused nanoporous surface (SLIPS) coating using nanoparticles and hydrophobic lubricants that effectively improves the flow rate and antifouling property of cannulas without altering the geometrical design parameter.