• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.509-515
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• 2004

In this paper we present the linear combination of a fuzzy opening and closing filter with locally adaptive structuring elements that can preserve the geometrical features of an image. Based on the adaptation algorithm of linear combination of the fuzzy opening and closing filter, the optimal structuring element for image representation is obtained. The optimal structuring element is an indicator of the shape and direction of an object's image, which is useful in filtering, multi resolution, segmentation, and recognition of an image.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.151-154
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• 2000

• Journal of Korean Association for Spatial Structures
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• v.13 no.1
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• pp.51-57
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• 2013

There can be diverse causes in the destruction of a large space structure by strong wind such as characteristics of construction materials and changes in internal and external wind pressure of the structure. To evaluate the wind pressure of roof against the large space structure, wind pressure experiment is performed. However, in this wind pressure experiment, peak internal pressure coefficient is set according to the opening of the roof in Korea wind code. In this article, it was tried to identify the change of internal pressure coefficient and the characteristics of wind pressure coefficient acting on the roof by two kinds of opening on the side of the structure with Hyperbolic Paraboloid Spatial Structures roof. When analyzing internal pressure coefficient according to roof shape, it was found that minimum (52%) and maximum (30%~80%) overestimation was made comparing to partial opening type proposed in the current wind load. It is judged that evaluation according to the opening rate of the structure should be made to evaluate the internal pressure coefficient according to load.

• Journal of Hydrogen and New Energy
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• v.35 no.4
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• pp.363-369
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• 2024

Needle valves are instrumentation devices with quick-opening inherent flow characteristics, used in pipelines requiring rapid flow supply immediately upon opening the flow path. For needle valves applied in liquefied hydrogen plants operating in cryogenic environments, it is necessary from the initial design stage to have various inherent flow characteristics in addition to quick-opening, depending on the intended usage. In this study, the inherent flow characteristics of a 1/2'' liquid hydrogen needle valve were evaluated through computational fluid dynamics analysis. Disk shapes exhibiting various inherent flow characteristics were proposed by deriving the flow coefficient (Cv) according to changes in disk shapes. Among the disk shapes that directly affect the Cv, the disk length and slope angle were selected, and case studies were conducted with nine parameter combinations. From the results of the normalized Cv regarding to opening rates, disk lengths and slope angles exhibiting quick-opening, equal-percentage, and linear inherent flow characteristics were determined.

• Steel and Composite Structures
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• v.28 no.5
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• pp.617-628
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• 2018

Steel shear wall possesses priority over many of the current lateral load-bearing systems due to reasons like higher elastic stiffness, desirable ductility and energy absorption, convenience in construction and implementation technology, and economic criteria. Besides these advantages, this system causes increase in the dimensions of other structural elements due to its high stiffness as one of its intrinsic characteristics. One of the methods for stiffness reduction is perforating the wall panel and creating openings in the wall that can also be used as windows or ducts in buildings service period. The aim of the present study is probing the appropriate geometric shape and location of opening to fulfil economic criterion plus technical and seismic design criteria. In the present research, a number of possible while reasonable opening shapes and locations are defined in various sizes for some steel shear wall specimens. The specimens are modelled in ABAQUS finite elements software and analyzed using nonlinear pushover analysis. Finally, the analyses' results are reported as force-displacement diagrams and the strength, the initial stiffness and the energy absorption are calculated for all specimens and compared together. The obtained results show that both shape and location of the openings affect the seismic parameters of the shear wall. The specimens in which the openings are further from the center and closer to the columns possess higher stiffness and strength while the specimens in which the openings are closer to the center show more considerable changes in their seismic parameters in response to increase in opening area.

• Tunnel and Underground Space
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• v.26 no.6
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• pp.475-483
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• 2016

A numerical analysis model capable of predicting the shape, the size and the potentiality of collapse of tetrahedral blocks considering the persistence obtained from the field survey of joint distribution around the underground excavation surface has been developed. Numerical functions of analyzing both the exposed trace distribution on the excavation surface and the formation of tetrahedral block controlled by the extent of joint surface have been established and linked to the previously developed three dimensional deterministic block analysis model. To illustrate the reliability of advanced numerical model the case of underground excavation in which the collapse of rock block had practically taken place was studied. Representative orientations of joint sets was determined based on the joint distribution pattern observed on the excavation surfaces. The formation of block on the roof of underground opening was analyzed to unveil the potential tetrahedral block the shape of which was very similar to the collapsed rock block. Mechanisms of collapse process has been also analyzed by considering the three dimensional shape of tetrahedral block.

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.113-120
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• 1991

The authors examined the patterns and various ranges of mandibular movements in TMJ lock closed patients in the frontal, sagittal and horizontal plane pre-end post-treatment. And the author obtained the following results. 1. In the frontal plane, the patterns and ranges of mandibular movement of the patients were very irregular and small before treatment. But after the treatment, the patterns were similar to the typical shield shape of the normal subjects. And the velocity of opening and closing was improved after the treatment. 2. In the sagittal plane, the mean amount of maximum mouth opening was 27.0±4.0mm before treatment and 44.0±5.4mm after treatment. And there was statistically significant improvement(p<0.005). The patterns of the movement were very irregular and small before treatment, but were similar to the shape of "Posselt's envelope of motion" after the treatment. The velocity of opening and closing was improved after the treatment 3. In the horizontal plane, the mean amount of maximum laterotrusion was 8l2±2.5mm in the affected side and 6.7±2.2mm in the non-affected side before treatment. There was a significant difference between the sides(p<0.05). After the treatment, the mean was 10.4±2.6mm in the affected side and 8.9±2.3mm in the non-affected side and there was no significant difference between the sides(p>0.05). There was no significant difference in the mean amount of maximum protrusion between the before and aftertreatment(p>0.05), but the patterns of the movements were improved.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.182-189
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• 2009

The noise from the sunroof can be divided into the low frequency buffeting noise and the high frequency turbulence noise generated when a car runs at the high driving speed. The wind deflector suppresses the buffeting noise generation by accelerating the vortex shedding from the front edge of sunroof opening, and guides the flow direction so that air can pass smoothly over the sunroof opening. To reduce the buffeting noise and the high frequency noise, it is very important to locate a deflector in a proper position depending on the driving speed and the sunroof opening width. The deflector's sectional shape also plays an important role in efficiently reducing the buffeting and high frequency noise. In this paper, we determined the optimum deflector's sectional shape and examined the flow characteristics behind a sunroof deflector through CFD analysis with changing the deflector height, the driving speed and the sunroof opening width. It is found that the deflector needs to be located in the higher location to control the buffeting noise by shedding the higher frequency vortices to accelerating vortices from the sunroof front edge. The deflector may act as a new noise source at the high driving speed, then it is desirable to put the deflector at the proper height to reduce the flow fluctuations and the noise generation. We also made a road test to verify CFD analysis results in this study.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.2
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• pp.73-88
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• 2000

A series of analysis and experiment on the fishing gear and method of the existing midwater pair trawl net with 12,800mm of maximum mesh size is carried out to determine the most effective shape factor. As the first step of this study, the fishing gear and method for the existing net are analyzed to solve problems, such as being low of the net height by increasing the towing speed, twist of net pendant and twine, suspension of float between knots of mesh. etc. Standing on these results, the existing net are modified by very effective shape based on the theory and technology designing the fishing gear. Also, the model experiment is carried out to determine the most effective shape factor of the modified net in the circulation water channel. The obtained results can be summarized as follows : 1. On the length of net pendants(No.2 and No.3) connected with side line, opening efficiency of net with length 8.0cm of net pendant is the greatest and in the order of 11.5cm, 15.0cm. 2. On the number of the net pendant, opening efficiency of net with 4 lines of net pendant is the greatest and in the order of 3 lines, 2 lines. Center part of side panel is pushed out backward, and the pushed length is increasing by increasing flow speed. 3. On the sinking force, opening efficiency of the net is increasing by increasing sinking force. And opening efficiency shows almost the same when sinking force is greater about 1.5 times than that of the existing net in case of the net with 3 lines of net pendant, and about 1.6 ~ 1.7 times than that of the existing net in case of the net with 2 lines.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.41-48
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• 2008

The aim of this study is to present a graphical method in order to evaluate stages in shrinkage cracking. Firstly, the distribution of crack openings is established by sorting the openings of individual cracks in the soil cracking system. Secondly, it is normalized in a range of 0 to 1 to obtain the normalized crack opening distribution. Thirdly, three S-shape curve models introduced by Brooks and Corey(1964), Fredlund and Xing(1994) and van Genuchten(1980) are chosen to fit the normalized crack opening distribution using a curve fitting method. The accuracy of fitting which is described through fitting parameters by the van Genuchten equation is much higher than that by the Brooks and Corey equation and slightly higher than that by the Fredlund and Xing equation; thus the van Genuchten model is used. Finally, the stages of shrinkage cracking are graphically evaluated by drawing three separate straight lines corresponding to three linear parts of the fitted normalized crack opening distribution. The proposed method is tested with different sample thicknesses. The measured data are fitted by the selected model with the fairly high regression coefficient and small root mean square error. The results show graphically that shrinkage cracking comprises three stages; namely, primary, secondary and residual stages. Subsequently, the ranges of evaluated crack opening for each of these stages are presented.