• 제어로봇시스템학회논문지
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• 제17권5호
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• pp.436-443
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• 2011

Recognition of structures in urban environments is a fundamental ability for unmanned ground vehicles. In this paper we propose the geometrical featured voxel which has not only 3-D coordinates but also the type of geometrical properties of point cloud. Instead of dealing with a huge amount of point cloud collected by range sensors in urban, the proposed voxel can efficiently represent and save 3-D urban structures without loss of geometrical properties. We also provide an urban structure classification algorithm by using the proposed voxel and machine learning techniques. The proposed method enables to recognize urban environments around unmanned ground vehicles quickly. In order to evaluate an ability of the proposed map representation and the urban structure classification algorithm, our vehicle equipped with the sensor system collected range data and pose data in campus and experimental results have been shown in this paper.

• 한국구조물진단유지관리공학회 논문집
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• 제8권2호
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• pp.169-175
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• 2004

본 연구에서는 채널단면을 갖는 캔틸레버 복합적층 구조물의 안정성에 다루었다. 보다 합리적이고 효율적인 설계의 기초자료를 제시하고자 채널단면의 길이비와 곡절각도 등과 같은 기하학적 형상변화와 화이버의 보강각도에 따른 좌굴거동을 분석하고, 그에 따른 상호작용에 의한 안정성을 파악하였다. 이를 근거로 캔틸레버 복합적층 구조물의 적절한 채널단면 및 복합재료의 적층구조형식 등을 공학적 측면에서 고찰하고 제시하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.806-809
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• 2003

Ion-induced secondary electron emission coefficient $({\gamma})$. of the patterned MgO thin film with geometrical structures has been measured by ${\gamma}$ - FIB(focused ion beam) system. The patterned MgO thin film with geometrical structures has been formed by the mask (mesh of ${\sim}$ $10{\mu}m^{2})$ under electron beam evaporation method. It is found that the higher ${\gamma}$. has been achieved by the patterned MgO thin film than the normal ones without patterning.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.1-8
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• 2012

In this paper, we improved the light extraction efficiency by structural change of LEDs on conventional LEDs. We simulated the LEDs light emission as functions of LED side wall angle, various refractive indices the geometrical structures and analyzed the condition improved the light efficiency. We present the results of experimerns and simulations for light output power from LEDs for various refractive indices and the geometrical structures of the LED encapsulants. When the side wall angle range was from 40[$^{\circ}$] to 30[$^{\circ}$], the LED emission increased. LED side wall angle onto LED using the simulation system with a fine tuning of the structure of the LEDs side wall angle is fabricated. Additionally, we changed the side wall angle of LED package with spherical structure and flat structure. The result of spherical structure ray tracting is higher compared with flat structure about 14[%].

• Computers and Concrete
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• 제33권1호
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• pp.91-102
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• 2024

Beam-shaped components commonly rotate along a fixed axis when massive mechanical structures like rotors, jet engine blades, motor turbines, and rotating railway crossings perform their functions. For these structures to be useful in real life, their mechanical behavior is essential. Therefore, this is the first article to use the modified shear deformation theory type hyperbolic sine functions theory and the FEM to study the static bending response of rotating functionally graded GPL-reinforced composite (FG-GPLRC) beams with initial geometrical deficiencies in thermal media. Graphene platelets (GPLs) in three different configurations are woven into the beam's composition to increase its strength. By comparing the numerical results with those of previously published studies, we can assess the robustness of the theory and mechanical model employed in this study. Parameter studies are performed to determine the effect of various geometric and physical variables, such as rotation speed and temperature, on the bending reactions of structures.

• 한국광물학회지
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• 제11권1호
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• pp.45-67
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• 1998

FORTRAN program PHYLS was developed to model the structures of 2:1 1M and 2M1 phyllosilicates on the basis of geometrical analyses. Input to PHYLS requires the chemical composition and d(001) spacing of the mineral. The output from PHYLS consists of the coordinates of the crystallographically independent sites in the unit cell, and such structural parameters as the cell dimensions, interaxial angle, cell volume, interatomic distances, and deformation angles of the polyhedra. PHYLS can generate these structural details according to the user's choice of space group and cation configuration. User can choose one of such space groups as C2/m, C2,and C2/c and such cation configurations as random and ordered tetrachedral/octahedral cation configurations. PHYLS simulated the structures of dioctahedral and trioctahedral phyllosilicates having random tetrahedral cation configuration fairly close to the reported experimentally determined structures. In contrast, the simulated structures for ordered tetrahedral cation configurations showed greater deviation from the experimentally determined structures than those for random configurations. However, if the cations were partially ordered and the sizes of the tetrahedra became similar, the simulated PHYLS may be helpful in various investigations on the relationships between structures and physicochemical properties of the phyllosilicates.

• Advances in Computational Design
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• 제7권3호
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• pp.189-210
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• 2022

Deployable structures have the ability to shift from a compact state to an expanded functional configuration. By extension, reconfigurability is another function that relies on embedded computation and actuators. Linkage-based mechanisms constitute promising systems in the development of deployable and reconfigurable structures with high flexibility and controllability. The present paper investigates the deployment and reconfigurability of modular linkage structures with a pin and a sliding support, the latter connected to a linear motion actuator. An appropriate control sequence consists of stepwise reconfigurations that involve the selective releasing of one intermediate joint in each closed-loop linkage, effectively reducing it to a 1-DOF "effective crank-slider" mechanism. This approach enables low self-weight and reduced energy consumption. A kinematics and finite-element analysis of different linkage systems, in all intermediate reconfiguration steps of a sequence, have been conducted for different lengths and geometrical characteristics of the members, as well as different actuation methods, i.e., direct and cable-driven actuation. The study provides insight into the impact of various structural typological and geometrical factors on the systems' behavior.

• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.452-459
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• 2004

The geometrical structures of various isomers of hexafluoro-1,3-butadiene (HFBD), tetrafluoro-1,3-butadiene (TFBD), and difluoro-1,3-butadiene (DFBD) have been studied theoretically. Natural steric and natural resonance theory (NRT) analyses indicate that the lower energy of skew s-cis conformer of hexafluoro-1,3-butadiene than that of the s-trans conformer is originated from the strong steric repulsions between fluorine atoms particularly in the s-trans conformer. The resonance structures generated by NRT also show that the lone electron pairs of fluorine atoms effectively extend the conjugation, and the large differences in energy among the structural isomers of tetrafluoro-1,3-butadiene and difluoro-1,3-butadiene are in part attributed to the differences in the delocalization energies, in addition to the steric repulsion between fluorine atoms. Other interatomic interactions, such as hydrogen bonding, also play important roles in determination of the structures of isomers of tetrafluoro-1,3-butadiene and difluoro-1,3-butadiene.

• Bulletin of the Korean Chemical Society
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• 제24권11호
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• pp.1649-1654
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• 2003

We have investigated substituent effect on the stabilization energies, and nucleus-independent chemical shifts of pentafulvalenes and on the electronic structures of the corresponding polypentafulvalenes to design environmentally stable semiconductive or conductive polymers. Geometrical optimizations of the molecules were carried out at the density functional level of theory with B3LYP hybrid functional and 6-311+G(d) basis set. Stabilization energies were estimated using isodesmic and homodesmotic reactions. As a criterion of aromaticity nucleus-independent chemical shifts of the molecules were computed using GIAO approach. For the polymers the geometrical parameters were optimized through AM1 band calculations and the electronic structures were obtained through modified extended Huckel band calculations. It is found that strong electronwithdrawing substituents increase isodesmic and homodesmotic stabilization energies of pentafulvalene, though it does not increase the aromaticity. Nitro-substituted pentafulvalene is estimated to have stabilization energy as much as azulene. However, substitution either with electron-donating groups or with electronwithdrawing groups does not significantly affect the electronic structures of polypentafulvalene and poly (vinylenedioxypentafulvalene).

• Ocean Systems Engineering
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• 제13권2호
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• pp.97-121
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• 2023

Through-the-thickness stress distribution in a tubular member has a profound effect on the fatigue behavior of tubular joints commonly found in steel offshore structures. This stress distribution can be characterized by the degree of bending (DoB). Although multi-planar joints are an intrinsic feature of offshore tubular structures and the multi-planarity usually has a considerable effect on the DoB values at the brace-to-chord intersection, few investigations have been reported on the DoB in multi-planar joints due to the complexity of the problem and high cost involved. In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified based on available parametric equations, was used to study the effects of geometrical parameters on the DoB values in two-planar tubular DYT-joints. Parametric FE study was followed by a set of nonlinear regression analyses to develop six new DoB parametric equations for the fatigue analysis and design of axially loaded two-planar DYT-joints.