• 수산해양기술연구
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• 제34권3호
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• pp.283-286
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• 1998

활주선 선형을 갖는 고속어선의 저항특성을 체계적으로 연구하기 위한 제 1단계로서 단면형상 및 장-폭비와 저항특성과의 관계에 대한 실험적 연구를 수행하였다. 본 연구는 새로운 고속 활주형 어선을 개발하기 위한 초기연구로서 다음의 내용을 포함하고 있다. - 4가지 단면형상에 대한 저항 특성 - 4가지 장-폭비에 대한 저항 특성

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.339-341
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• 2006

This paper proposes a method of container position measurement using automatic landing system that is estimated by a laser range finder. In the most of container position measurement methods, CCD cameras or laser scanners have been used to get the source data. However those sensors are not only weak for disturbances, for examples, the light, fog, and rain, but also the system cost is high. When the spreader arrives the goal position, it is still swung by inertia or by wind effect. In this paper, the spreader swung data have been used to find the container position. The laser range finder is equipped in the front side of spreader. It can measure distance and relative position between spreader and container. This laser range finder can be rotated as desired by a motor. And a tilt sensor is equipped on the spreader to measure spreader sway. We estimate the relative position information between the spreader and a container using the laser range finder and tilt sensor through the geometrical analysis.

• Computers and Concrete
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• 제14권1호
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• pp.41-57
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• 2014

Modern trend in structural design is to use smaller elements in order to ensure several purposes such as economy, functionality and aesthetic in appearance. However, because of decreasing rigidity of the structural elements, the system displacements increases and displacements become an important subject in this kind of structures takes into account both geometrical changes and the carrying capacity of the material after linear-elastic boundary. In this study, a method is proposed to calculate the failure loads and to analyse the reinforced concrete space frame systems. The numerical examples gathered from the literature survey are solved with this method utilising the prepared computer program and the comparable results are presented. The results show that the method is sufficiently accurate.

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.329-337
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• 2017

This study concerns the vibrational behavior of multi-walled nested silicon-carbide and carbon nanotubes using the finite element method. The beam elements are used to model the carbon-carbon and silicon-carbon bonds. Besides, spring elements are employed to simulate the van der Waals interactions between walls. The effects of nanotube arrangement, number of walls, geometrical parameters and boundary conditions on the frequencies of nested silicon-carbide and carbon nanotubes are investigated. It is shown that the double-walled nanotubes have larger frequencies than triple-walled nanotubes. Besides, replacing silicon carbide layers with carbon layers leads to increasing the frequencies of nested silicon-carbide and carbon nanotubes. Comparing the first ten mode shapes of nested nanotubes, it is observed that the mode shapes of armchair and zigzag nanotubes are almost the same.

• Earthquakes and Structures
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• 제13권3호
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• pp.241-253
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• 2017

In this paper, dynamic response of the horizontal nanofiber reinforced polymer (NFRP) strengthened concrete beam subjected to seismic ground excitation is investigated. The concrete beam is modeled using hyperbolic shear deformation beam theory (HSDBT) and the mathematical formulation is applied to determine the governing equations of the structure. Distribution type and agglomeration effects of carbon nanofibers are considered by Mori-Tanaka model. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle (virtual work method), the governing equations are derived. To obtain the dynamic response of the structure, harmonic differential quadrature method (HDQM) along with Newmark method is applied. The aim of this study is to investigate the effect of NFRP layer, geometrical parameters of beam, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure up to 91 percent. In addition, using nanofibers as reinforcement leads a 35 percent reduction in the maximum dynamic displacement of the structure.

• 한국전산유체공학회지
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• 제19권1호
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• pp.73-79
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• 2014

Three-dimensional turbulent flows of a distribution manifold are studied by a turbulence model. To investigate the geometrical effects of the manifold, the length and area of exit port are changed. From the results, flow structures related to the outflow uniformity are examined and the deparure angles are obtained. The exit configuration depending on the departure angle has advantages to the outflow uniformity. That is, the decreased exit area in the streamwise direction improves the uniformity of exit flow. For the uniform effusion, the change of exit port by departure angle is more effective them the change of exit area.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.152-155
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• 2008

In this paper, the effect of modification of geometric variables on the performance of a centrifugal compressor blade has been studied numerically. The compressor contains six main blades and six splitter blades. Reynolds averaged Navier-Stokes (RANS) equations with shear stress turbulence (SST) model are discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The design variables from blade lean angle at tip and middle of the blade have been modified. The isentropic blade efficiency and pressure have been predicted with the variation of the variables. Frozen rotor simulation is performed and adiabatic wall condition has been used. One of the six blades of compressor has been used for simulation to reduce the computational load. Optimum number of meshes has been selected by grid-dependency test, and this is used for all the simulations with changing geometric variables. The detailed flow analysis results have been reported as well as the effects of the variables.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.138-143
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• 2008

Recently, a new periodic cellular metal(PCM) named as Wire wove Bulk Kagome(WBK) was introduced. Based on the shape of tetrahedra composing a WBK, WBKs are classified into two types, namely, concave and convex type. They are easily differentiated by changing the assembling sequence. The effect of geometrical parameters such as the wire diameter, strut length and number of layers on the compressive behavior of concave type WBK has already been investigated. In this work, the similar works were performed with the convex type WBKs. It was shown that the compressive strength of the convex type WBK was quite similar to that of the concave type. The compressive strengths of convex type specimens also depend on the slenderness ratio, but a little different from those of concave type specimens in the detailed behavior. And densification occurs earlier than the concave type WBK.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2001년도 추계학술발표대회 논문집 제20권 2호
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• pp.379-382
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• 2001

In the muffler industry, the main purpose of the research works is to determine a way to increase the TL (Transmission Loss) properties of the muffler, without deteriorating the back pressure influence. In order to obtain better results, several works have been done by changing the geometrical characteristics of the muffler or the type of the muffler. This work will focus on the perforated muffler components with concentric chamber, to investigate the effect of a non-uniform porosity along the inner perforated tube of the muffler on the TL. It is noted that varying the perforation ratio affects the peaks frequencies of the TL, especially fer $2\pi < kL < 4\pi$ (in the case of L : 200mm for the concentric resonator). The magnitudes of the TL, for this range of frequencies, vary noticeably by changing the porosity distribution.

• Macromolecular Research
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• 제13권3호
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• pp.180-186
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• 2005

A novel bifunctional dye composed of spirobenzopyran and a cinnamoyl moiety was prepared and its photochromic behavior under the illumination of monochromatic UV light was investigated. This colorless bifunctional dye exhibits typical photochromism in both the film and in solution, through the structural and geometrical transformation from spirobenzopyran to merocyanine accompanied by a photocrosslinking reaction between the cinnamoyl moieties. Two kinds of photochemical reaction were selectively achieved by irradiation with monochromatic UV light at wavelengths of 275 and 365 nm, respectively. The effect of the selective photochemical reaction on the photochromism of the dye and its decaying behavior was investigated.