• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.95-104
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• 2004

This paper describes the design, fabrication, and measurement of a omni-directional beam pattern antenna for base station of the BIS which is one of the ITS services. The antenna is installed on the signal lamp of important crossroad and provides the wireless communication link between vehicles and RSE(Road Side Equipment). The required characteristics of BIS base station antenna are omni-directional beam pattern and specific beam pattern by the road and install environment and installed place of OBU. To get omni-directional beam pattern of antenna, Array configuration and OMA are applied. The measured results of fabricated antenna are as follows; return loss of 640MHz by -10 dB, and a gain of 10.3dBi. It is found that the measured beam patterns are similar to design results.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.5-12
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• 2010

The purpose of this study is to analyze heterogeneous distribution of branch-like structure at downstream region of inner spray. The previous many studies about diesel spray structure have yet stayed in the analysis of 2-D structure, and there are very few of informations which are concerned with 3-D analysis of the structure. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray, and also the combustion characteristics of the diesel engines. Therefore, in order to investigate 3-D structure of evaporative spray the laser beam of 2-D plane was used in this study. Liquid fuel was injected from a single-hole nozzle (l/d=5) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. The incident laser beam was offset on the central axis. From the images analysis taken by offset of laser beam, we examine formation mechanism of heterogeneous distribution by vortex flow at the downstream of the diesel spray. As the experimental results, the branch-like structure formed heterogeneous distribution of the droplets consists of high concentration of vapor phase in the periphery of droplets and spray tip of branch-like structure. Also the 3-D spatial structure of the evaporative diesel spray can be verified by images obtained from 2-D measurement methods.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.77-84
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• 2021

In this study, In order to apply the U-flanged truss hybrid beam to the actual construction site, the structural design of the basic module of the middle and low-rise neighborhood living facilities was performed according to the Korea Design Standard, and the construction cost and construction period were compared with the traditional reinforced concrete structure system. As a result of analyzing the construction cost for the basic module, if the U-flanged truss hybrid beam and D-Deck slab system are used, the construction cost can be reduced by 86% compared to the traditional reinforced concrete structure system. In addition, as a result of analyzing the construction period for a floor area of 1,000m², using the U-flanged truss hybrid beam and D-Deck slab system can save 2.0days in construction period compared to the traditional reinforced concrete structure system. Therefore, the U-flange truss hybrid beam can secure sufficient economic feasibility compared to the existing reinforced concrete method in terms of cost reduction and shortening of construction period.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3403-3414
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• 2022

The purpose of this study is to model and optimize the block-matching and 3D filtering (BM3D) algorithm and to evaluate its applicability in brain single-photon emission computed tomography (SPECT) images using a fan beam collimator. For quantitative evaluation of the noise level, the coefficient of variation (COV) and contrast-to-noise ratio (CNR) were used, and finally, a no-reference-based evaluation parameter was used for optimization of the BM3D algorithm in the brain SPECT images. As a result, optimized results were derived when the sigma values of the BM3D algorithm were 0.15, 0.2, and 0.25 in brain SPECT images acquired for 5, 10, and 15 s, respectively. In addition, when the sigma value of the optimized BM3D algorithm was applied, superior results were obtained compared with conventional filtering methods. In particular, we confirmed that the COV and CNR of the images obtained using the BM3D algorithm were improved by 2.40 and 2.33 times, respectively, compared with the original image. In conclusion, the usefulness of the optimized BM3D algorithm in brain SPECT images using a fan beam collimator has been proven, and based on the results, it is expected that its application in various nuclear medicine examinations will be possible.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.1-11
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• 1998

One of the desired features for the realizations of high quality Information and Telecommunication services in future is "the Sensation of Reality". This will be achieved only with the visual communication based on the 3- dimensional (3-D) moving images. The main difficulties in realizing 3-D moving image communication are that there is no developed data transmission technology for the hugh amount of data involved in 3-D images and no established technologies for 3-D image recording and displaying in real time. The currently known stereoscopic imaging technologies can only present depth, no moving parallax, so they are not effective in creating the sensation of the reality without taking eye glasses. The more effective 3-D imaging technologies for achieving the sensation of reality are those based on the multiview 3-D images which provides the object image changes as the eyes move to different directions. In this paper, a multiview 3-D imaging system composed of 8 CCD cameras in a case, a RGB(Red, Green, Blue) beam projector, and a holographic screen is introduced. In this system, the 8 view images are recorded by the 8 CCD cameras and the images are transmitted to the beam projector in sequence by a signal converter. This signal converter converts each camera signal into 3 different color signals, i.e., RGB signals, combines each color signal from the 8 cameras into a serial signal train by multiplexing and drives the corresponding color channel of the beam projector to 480Hz frame rate. The beam projector projects images to the holographic screen through a LCD shutter. The LCD shutter consists of 8 LCD strips. The image of each LCD strip, created by the holographic screen, forms as sub-viewing zone. Since the ON period and sequence of the LCD strips are synchronized with those of the camera image sampling adn the beam projector image projection, the multiview 3-D moving images are viewed at the viewing zone.

• Steel and Composite Structures
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• v.15 no.3
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• pp.247-266
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• 2013

This paper presents a comparison of results obtained by a newly developed numerical model for predicting the behaviour of structures under fire with experimental study carried out on heated and simply supported steel beam elements. A newly developed numerical model consists of three submodels: 3D beam model designed for calculating the inner forces in the structure, 2D model designed for calculation of stress and strain distribution over the cross section, including the section stiffness, and 3D transient nonlinear heat transfer model that is capable of calculating the temperature distribution along the structure, and the distribution over the cross section as well. Predictions of the calculated temperatures and vertical deflections obtained by the numerical model are compared with the results of the inhouse experiment in which steel beam element under load was heated for 90 minutes.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.764-771
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• 2006

The use of 3-D finite elements for the eigen analysis of beam-like structures with arbitrary section shape may not be practical in certain cases, from the aspect of CPU time. In this connection, this paper presents a systematic algorithm for decomposing an arbitrary section into finite number of basic ones and computing essential sectional quantities required for the eigen analysis using the beam theory. The numerical accuracy of the proposed method is assesed from the comparison with the 3-D finite . element method.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1068-1073
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• 2007

3D finite element analyses of a corrugated steel web girder and a steel truss web girder are conducted to investigate the static and dynamic behaviour of the hybrid girders. And the analyses results are compared with those by the equivalent beam theory. The equivalent theory is a theory that all section properties of a truss structure are replaced by section properties of a beam including the shear coefficient. When applying the equivalent beam theory, the shear coefficient of the corrugated steel web girder is estimated as the area ratio of total section to web section and that of the steel truss web girder is calculated by the equation proposed by Dewolf. Static deflections and natural frequencies by 3D finite element analyses and the those by the equivalent beam theory are relatively in good agreement.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.601-625
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• 2014

Based on continuum mechanics and the principle of virtual displacements, incremental total Lagrangian formulation (T.L.) and incremental updated Lagrangian formulation (U.L.) were presented. Both T.L. and U.L. considered the large displacement stiffness matrix, which was modified to be symmetrical matrix. According to the incremental updated Lagrangian formulation, small strain, large displacement, finite rotation of three dimensional Timoshenko fiber beam element tangent stiffness matrix was developed. Considering large displacement and finite rotation, a new type of tangent stiffness matrix of the beam element was developed. According to the basic assumption of plane section, the displacement field of an arbitrary fiber was presented in terms of nodal displacement of centroid of cross-area. In addition, shear deformation effect was taken account. Furthermore, a nonlinear finite element method program has been developed and several examples were tested to demonstrate the accuracy and generality of the three dimensional beam element.