• Journal of radiological science and technology
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• v.33 no.4
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• pp.341-348
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• 2010

By accessing the current status of FPD system use in the hospitals located in Seoul and Gyeonggi Province as well as the entrance skin dose and the image quality evaluation realized by C-D Phantom, and the image assessment by the medical professionals regarding the radiography for the extremity, the following results were derived. 1. According to the evaluation made in the actual use of FPD system (12 machines), the grid ratio varied from 8:1 to 13:1, and 6 machines used the grid ratio with 12:1, realizing the largest number. Among the machines, there were 8 machines that allowed a removable grid while 3 machines did use a removable grid (25.0%). 2. When it came to the equipments used for the experiment, it showed that the amount of the entrance skin dose increased from 4.13 times up to 4.79 times with the grid use. 3. The difference in the entrance skin dose depending on the changes in the exposure condition(0.5times or 2.0times) was not significantly different regardless of the patients' thickness. 4. In terms of the image quality depending on C-D Phantom, the grid use was distinguished well. However, the images were well distinguishable as the exposure condition got increased. 5. In the clinical assessment, the grid use was less effective for the Hand PA, which was considered to shoot a thin body part. It was evaluated that the grid use was preferred for the Knee AP, which was shooting for a relatively thick body part. Nonetheless, 3 out of 5 people said that they would not use the grid if the entrance skin dose to reduced.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.51-55
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• 2004

A composite Iso-grid panel is manufactured and tested by compressive load. Vertical stringers and side stringers are joined with skin by secondary bonding using a liquid type adhesive. Bonding fixtures were developed to attach the stringers to skin. A-scan was done for inspection of secondary bonding region. The out of displacement field is visualized by shadow moire system. The strain and vertical displacement are measured by strain gages and L VDT (Linear Variable Differential Transformer). A local buckling is occurred at all grid sections. After that, the final failure is occurred. The strain of side stringer is much less than that of vertical stringer and skin. Due to the side stringer, the local buckling is delayed. Therefore the ratio of the first buckling to failure load is greater than that of vertical stringer stiffened panel.

• Journal of radiological science and technology
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• v.15 no.2
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• pp.3-9
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• 1992

In an experiment using chest radiography, the authors measured the scattered ray content ratio and exposed skin dose giving varieties to the object thickness, tube voltage, additional filters and gird. The result was as follows, In the 80 kV the required mAs for the density 1.8 was $10{\sim}20$ times as much as in the 140 kV, and when 10 : 1 grid was used the required mAs was $3{\sim}5$ times as much as when grid was not used. Under the same tube voltage the scattered ray content ratios were increased as the additional filter thickness became thicker. And when 10 : 1 grid was used the ratio could be decreased $2{\sim}5$ times as much as when grid was not used. Skin doses exposed to the patients were increasing as the thickness of the object became thicker, and were decreasing as filters became thicker while showing slow the decreasing effects above the 1/8 VL. And when the grid was used skin doses were increased $2{\sim}4$ times as much as when not used. In order to improve the image qualities while reducing the exposures in the chest radiography, the authors suggest followings. The additional filters up to the 1/2 VL will be suitable according to the thickness of the objects in the 80kv, while the 10 : 1 grid and additional filter of 1/8 VL will be suitable in the 140 kV.

• Computational Structural Engineering : An International Journal
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• v.3 no.1
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• pp.19-29
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• 2003

In the present study, finite element linear buckling analysis is performed for grid-stiffened composite plates. A hybrid element with drilling degrees of freedom is employed to reduce the effect of the sensitivity of mesh distortion and to match the degrees of freedom between skins and stiffeners. The preliminary static stress distribution is analyzed for the determination of accurate load distribution. Parametric study of grid structures is performed and three types of buckling modes are observed. The maximum limit of buckling load was found at the local skin-buckling mode. In order to maximize buckling loads, stiffened panels need to be designed to be buckled in skin-buckling mode.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.844-847
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• 2005

A seamless analysis of complex geometry is one of greatly interesting topic. However, there are still gaps between the industrial applications and fundamental academic studies owing to time consuming modeling process. To resolve this problem, an auto mesh generation program based on grid-based approach has been developed for IT-product in the present study. At first, base mesh and skin mesh are generated using the information of entities which extracted from IGES file. Secondly the provisional core mesh with rugged boundary geometry is constructed by superimposing the skin mesh as well as the base mesh generated from the CAD model. Finally, the positions of boundary nodes are adjusted to make a qualified mesh by adapting node modification and smoothing techniques. Also, for the sake of verification of mesh quality, the hexahedral auto mesh constructed by the program is compared with the corresponding tetrahedral free mesh and hexahedral mapped mesh through static finite element analyses. Thereby, it is anticipated that the grid-based approach can be used as a promising pre-processor for integrity evaluation of various IT-products.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.55-61
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• 1998

The purpose of this study is to compare the predictive behaviors of the extended $k-{\varepsilon}$ turbulence model and the standard $k-{\varepsilon}$ turbulence model. Grid dependency is tested with the H-type grid and the O-type grid. Computations have been performed for a circular-to-rectangular transition duct. Numerical results for several sections along the streamwise have been obtained to compare with experimental results. The Reynolds number is 390,000 based on the bulk velocity at the inlet. The computed axial velocity contours, transverse velocity profiles, static pressure contours, peripheral skin friction coefficient, and peripheral wall static pressure distributions have been compared with experimental results. The computed results obtained with the extended $k-{\varepsilon}$ turbulence model show better agreement with experimental results than those obtained with the standard $k-{\varepsilon}$ turbulence model. Comparing to the computed results obtained with the H-type grid and O-type grid, those with H-type grid agree well with experimental results.

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.9-16
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• 1998

Predictive behaviors by the extended k-${\varepsilon}$ turbulence model and the standard k-${\varepsilon}$ turbulence model are compared. Grid dependency is tested with the H-type grid as well as the O-type grid. Computations have been performed on a circular-to-rectangular transition duct. The Reynolds number is 390,000 based on the bulk velocity at the inlet. The computed axial velocity contours, transverse velocity profiles, static pressure contours, peripheral skin friction coefficient, peripheral wall static pressure distributions and turbulence kinetic energy have been compared with experimental results. The computed results than those obtained with the standard k-${\varepsilon}$ turbulence model. Comparing to the computed results obtained with the H-type grid and O-type grid, those with H-type grid seem to agree well with experimental results.

• Geotechnical Engineering
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• v.12 no.4
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• pp.87-100
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• 1996

The pull -out test has been used to investigate the friction properties between soil and grid type geosynthetics which is useful to measure the passive bearing resistance as well as the skin friction. In this paper, the friction properties between geogrid and a weathered granite soil are investigated by performing various pull-out tests. From the test results, a rational pull out test equipment and test method is suggested by evaluating the effects of major factors (such as geogrid width, location of soil box facing, vertical loads and pulll -out displacement rate, etc.) on pull -out test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1051-1057
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• 2013

In this study, an automatic surface-strain measurement system called "ASIAS-bio" has been developed. This system can be used even in cases in which it is very difficult to apply a regular grid pattern necessary for measuring surface-strain, such as curved or uneven surfaces; surfaces damaged by corrosion or contamination; or soft materials such as rubber, foam, and biological tissues. This system works independently of the measurement conditions including the material and its surface condition, grid pattern and size, grid marking method, and degree of deformation. A comparison between the strain distributions of the sheet metal parts measured by using this system and those obtained by a commercial system showed that this system was sufficiently reliable. In addition, the deformation of the swine joint capsule and human knee skin was measured by using this system to demonstrate its usefulness.

• Journal of Korea Entertainment Industry Association
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• v.15 no.7
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• pp.145-158
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• 2021

This study is aimed at identifying the important factors required by customers through importance-satisfaction analysis of how they choose skin care shops on the basis of certain factors and attributes at this time when there is an urgent need to improve the level of quality that meets their expectations and demands in combination with the quantitative expansion of skin care shops. To achieve this, a survey was carried out to 217 people over the age of 20 in Gwangju and Jeonnam area with experience in using skin care shop services. The SPSS v. 21.0 program was used to analyze the collected data. The results are summarized as follows. IPA grid analysis of the difference in importance-satisfaction of sub-factors for skin care shop choice showed that the items corresponding to the upper-left side of maintenance and strengthening, the upper-right side of stainability, and the lower-left side of gradual improvement were the 'sanitary control of tools and products', 'basic situation(legal compliance)', and 'workers' sanitary control', 'internal control of skin care shops', 'professionalism and skills of workers'and 'quality of services', respectively. Consequently, the results of this study will be based on the efficient operation of skin care shops, and further more the utilization of them is expected to expand the quantitative and qualitative base of the skin care industry.