• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.577-582
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• 2007

A variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions in analysis domain arc generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Thus. the solution space can be represented in terms of the same functions to represent the geometry. The coefficients of basis functions or the control variables play the role of degrees-of-freedom. Furthermore, due to h-. p-, and k-refinement schemes, the high order geometric features can be described exactly and easily without tedious re-meshing process. The isogeometric sensitivity analysis method enables us to analyze arbitrarily shaped structures without re-meshing. Also, it provides a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling. To obtain precise shape sensitivity, the normal and curvature of boundary should be taken into account in the shape sensitivity expressions. However, in conventional finite element methods, the normal information is inaccurate and the curvature is generally missing due to the use of linear interpolation functions. A continuum-based adjoint sensitivity analysis method using the isogeometric approach is derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of boundary. In isogeometric analysis, however, the geometric properties arc already embedded in the B-spline shape functions and control points. The perturbation of control points in isogeometric analysis automatically results in shape changes. Using the conventional finite clement method, the inter-element continuity of the design space is not guaranteed so that the normal vector and curvature arc not accurate enough. On tile other hand, in isogeometric analysis, these values arc continuous over the whole design space so that accurate shape sensitivity can be obtained. Through numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• Macromolecular Research
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• v.12 no.1
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• pp.100-106
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• 2004

We have prepared the polymethylene-bridged, dinuciear, half-sandwich constrained geometry catalysts (CGC)［Zr(η$\^$5/:η$^1$-C$\_$9/H$\_$5/SiMe$_2$NCMe$_3$)］$_2$［(CH$_2$)$\_$n/］［n=6(9), n=12(10)］by treating 2 equivalents of ZrCl$_4$with the corresponding tetralithium salts of the ligands in toluene. $^1$H and $\^$13/C NMR spectra of the synthesized complexes provide firm evidence for the anticipated dinuciear structure. In $^1$H NMR spectra, two singlets representing the methyl group protons bonded at the Si atom of the CGC are present at 0.88 and 0.64 ppm, which are considerably downfield positions relative to the shifts of 0.02 and 0.05 ppm of the corresponding ligands. To investigate the catalytic behavior of the prepared dinuciear catalysts, we conducted copolymerizations of ethylene and styrene in the presence of MMAO. The prime observation is that the two dinuclear CGCs 9 and 10 are not efficient for copo-lymerization, which definitely distinguishes them from the corresponding titanium-based dinuclear CGC. These species are active catalysts, however, for ethylene homopolymerization; the activity of catalyst 10, which contains a 12-methylene bridge, is larger than that of 9 (6-methylene bridge), which indicates that the presence of the longer bridge between the two active sites contributes more effectively to facilitate the polymerization activity of the dinuciear CGC. The activities increase as the polymerization temperature increases from 40 to 70$^{\circ}C$. On the other hand, the molecular weights of the polyethylenes are reduced when the polymerization temperature is increased. We observe that dinuciear metallocenes having different-length bridges give different polymerization results, which reconfirms the significant role that the nature of the bridging ligand has in controlling the polymerization properties of dinuclear catalysts.

• Tunnel and Underground Space
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• v.29 no.4
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• pp.230-242
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• 2019

While various automatic rock fracture survey methods have been researched, the evaluation of the accuracy of these methods raises issues due to the absence of a metric which fully expresses the similarity between automatic and manual fracture maps. Therefore, this paper proposes a geometry similarity metric which is especially designed to determine the overall similarity of fracture maps and to evaluate the accuracy of rock fracture survey methods by a single number. The proposed metric, Scanline Intersection Similarity (SIS), is derived by conducting a large number of scanline surveys upon two fracture maps using Python code. By comparing the frequency of intersections over a large number of scanlines, SIS is able to express the overall similarity between two fracture maps. The proposed metric was compared with Intersection Over Union (IoU) which is a widely used evaluation metric in computer vision. Results showed that IoU is inappropriate for evaluating the geometry similarity of fracture maps because it is overly sensitive to minor geometry differences of thin elongated objects. The proposed metric, on the other hand, reflected macro-geometry differences rather than micro-geometry differences, showing good agreement with human perception. The metric was further applied to evaluate the accuracy of a deep learning-based automatic fracture surveying method which resulted as 0.674 (SIS). However, the proposed metric is currently limited to 2D fracture maps and requires comparison with rock joint parameters such as RQD.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.568-575
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• 2015

A hand-made vehicle with a formula (VF-1) was designed and manufactured with the aim of realizing a lightweight and high-performance vehicle. The driver's body weight and stiffness of the frame were considered. The vehicle was equipped with a one-cylinder Exiv 250 engine with intake manifold potting for realizing weight reduction, high performance, and low cost. The suspension system for the formula was designed through the analyses and tests of vehicle motion and equipment. In a steering system, anti-Ackerman geometry was introduced to increase the transverse force during cornering. A full electric paddle shift system was adopted to decrease the braking distance. For protection against the distortion and warping of the frame, tungsten inert gas (TIG) welding technology was used.

• Korean Institute of Interior Design Journal
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• v.17 no.2
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• pp.122-129
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• 2008

Rudolph Michael Schindler(1887-1953) has been known as one of the pioneering modem architects who pursued not merely stylistic expression but a true embodiment for the human life. His furniture design is particularly noteworthy in Schindler's building. He designed numerous furniture designs where it serves as a core principal of his interior design of each building. Nevertheless, despite his architectural accomplishments, his furniture design has less been discussed. This research focuses on investigating the notion and the characteristics of Schindler's furniture designs based on his architectural language. For an in depth study of Schindler's furniture, this study reconstructs the archival material by analyzing drawings and by fabricating scaled models to reveal the characteristics of Schindler's furniture. To do so, it concentrates on two things: On the one hand, the stylistic characteristics that have to do with simple geometry, human proportion, the use of material and visual technique; on the other hand, different furniture types. This article concludes by describing Schindler's furniture design that has grown from his unique design approach and its underlying formal and spatial design principles.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.28-34
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• 2013

This study is experimentally performed for using the oyster shell as a desiccant in the fluidized bed with bundle of heating pipe. The test material is oyster shell from fishery wastes which can use without costs. The main parameters of experiment are inlet air temperature, velocity of inlet air and heat flux of heating pipes. Also the geometry of heating pipe is treated as important parameter. From this study, the effect of inlet air temperature and input heat flux have much affect to increase the heat and mass transfer. On the other hand, the effect of inlet air velocity has less affect to increase the heat and mass transfer. And it is clarified that the oyster shell has sufficient probability for using as a desiccant in air-conditioning system.

• Transactions of Materials Processing
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• v.26 no.2
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• pp.108-114
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• 2017

Titanium based implants are known to improve their osseointegration by controlling surface roughness from nanometers to micrometers. Implants continuously and/or repeatedly receive irregular loads in the human body, and require a deeper understanding of the tensile and fatigue properties that can determine the fracture characteristics of the materials. In this study, the plastic deformation behavior which depends on the surface geometry of the materials during tensile tests was analyzed using the finite element method. As a result, the tensile properties were greatly decreased with increasing the sharpness of the surface. On the other hand, the average roughness had no significant effect on tensile properties. This investigation shed a light on developing titanium implants with improved osseointegration by surface treatments.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.48-62
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• 1988

A triple hot-wire probe has an essential potentiality for the measure- ment of an instantaneous velocity vector in a three dimensional unsteady flow with large amplitude of velocity fluctuations, the key problems asso- ciated with this instrument are the directional range of applicability and the accuracy. This present paper is concerned with a new method of the techniques of calibration and data processing to estimate the three dimensional flow field using an arbitrary shaped triple hot-wire probe. The method is not based on the assumptions of orthogonality or symmetry and it is especially useful for applications to a hand-made probe where probe geometry is not accurately known. The test application is made to evaluate the effect of cone angles of symmetric non-orthogonal probe.

• Korean Journal of Child Studies
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• v.16 no.1
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• pp.79-88
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• 1995

The purpose of this study was to investigate whether the experience of computer programming in Logo geometry advances the development of young children's concepts and/or representation of Euclidian spatial relations, particularly their concepts of the vertical-horizontal. Papert's claim of the positive effects of Logo programming experiences on young children's cognitive development was tested using the Piagetian Water Level Test (PWLT), the Free Hand Drawing Test (FHDT), and the Computer Drawing Test (CDT). Forty-four subjects were drawn from 2nd graders attending a public elementary school in Ithaca. The subjects were divided into 2 groups: a treatment group (TG) with Logo training for 10 weeks and a control group (CG) without Logo training. Our results showed that TG did not make any significant improvement on PWLT. In contrast, TG outperformed CG on FHDT. We suggested several possible explanations for this contradiction.

• Korean Journal of Mathematics
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• v.22 no.3
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• pp.567-581
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• 2014

Over the years, there has been much research conducted on quadratic curves and the set of points with the generalized notion of eccentricity in a plane with metrics such as taxicab distance or Chinese-checker distance. On the other hand, polar taxicab distance has been newly proposed on the polar coordinate system, a type of curvilinear coordinate system, to overcome the limitation of pre-existing metrics in terms of describing curved routes. Previous study has looked into the fundamental properties of this metric. From this point of view, we study the quadratic curves and the set of points with the generalized notion of eccentricity in a plane with polar taxicab distance.