• The Journal of Engineering Geology
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• v.24 no.2
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• pp.179-189
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• 2014

We analyzed the three-dimensional distribution of micropores and internal structures in both fresh and weathered granite using micro-focus X-ray computed tomography (micro-CT). Results show that the pore radius in fresh granite is mostly in the range of $17-50{\mu}m$, the throat radius is in the range of $5-25{\mu}m$, and the coordination number (CN) of pores is less than 10. In contrast, the pore radius in weathered granite is mostly in the range of $20-80{\mu}m$, the throat radius is in the range of $8-30{\mu}m$, and the CN is less than 12. In general, a positive linear relationship exists between pore radius and CN. In addition, both the size and the density of pores increase with an increasing degree of rock weathering. The size of the throats that connect the pores also increases with an increasing degree of weathering, which induces fracture propagation in rocks. Micro-CT is a powerful and versatile approach for investigating the three-dimensional distributions of pores and fracture structures in rocks, and for quantitatively assessing the degree of pore connectivity.

• Journal of the Korean Society of Combustion
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• v.22 no.2
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• pp.50-56
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• 2017

This study was conducted an experiment for the thermal flow mechanism of the surrounding butane gas can and pressure change in butane can with oversized cookware. And numerical analysis was performed to analyze the process of heat transfer around butane can. Effect of radiant heat from small size cookware is very small. Thus small size cookware does not have a significant impact on the butane gas range safety. But radiant heat of oversized cookware is larger than small size cookware. Therefore it gives an adverse effect on the butane can. And when internal pressure of butane can is greater than about 406.8~447.2 kPa, a safety device of portable butane gas range were working. The causes of safety device working is because of trivet height. Trivet height is lowered, the radiant heat is increased. This radiant heat is to raise pressure of inside butane can. Experimental and numerical analysis results, the lower thermal conductivity of the cookware is greater the effects of radiant heat.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.37-45
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• 1999

Many automated welding equipment are used in the industry. However, there are some problems to get quality welds because of the geometric error, thermal distortion, and incorrect joint fit-up. These factors can make the gap between base plates in case of a thick plate welding. The welding product with the quality welds can not be obtained without consideration of the gap. In this paper, the robot path and welding conditions are modified to get the quality weld by detecting the position and size of the gap. In this work, a low-priced laser range sensor is used. The 3-dimensional information is obtained using the motion of a robot, which holds a laser range sensor. The position and size of the gap is calculated using signal processing of the measured 3-dimensional information of joint profile geometry. The data measured by a laser range sensor is segmented by an iterative end point method. The segmented data is optimized by the least square method. The existence of gap is detected by comparing the data with the segmented shape of template. The effects of robot measuring speed and gap size are also tested. The recognizability fo the gap is verified as good by comparing the real joint profile and the calculated joint profile using the signal processing.

• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.253-260
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• 2013

In this study, laboratory model test carried out to present the suitable range of particle size distribution and clogging behavior of recycled aggregates and crushed stone as horizontal drains in soft ground. The recycled aggregates and crushed stone showed clogging phenomenon because the top fill material and bottom clay inflow into the horizontal drains. The pp mat was the most effective method to minimize clogging phenomenon. The horizontal coefficient of permeability in case of installing the pp mat showed largely 2.1 times more than the case of not installing. When the pp mat is not installing, the thickness of fine grained soil inflow into the horizontal drains showed 6.7~13.3% range in top fill material and 3.3~6.7% range in bottom clay. Overall, the reduction of the discharge capacity by fine grained soil inflow showed small in recycled aggregates and crushed stone. Also, the appropriate criterion range of particle size distribution is presented to make use of a horizontal drains in soft ground on the basis of laboratory test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.425-429
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• 2014

The visibility range is defined from where one can see. And it can be changed by illuminance, the character size, and eyesight and so on. In this paper the visibility range of 120 students is measured for 4 character sizes and 3 illuminations in a classroom. In order to forecast the visibility range of unmeasured data, using least square approximation theory, functions whose independent variable is illuminance and whose dependent variable is the visibility range is proposed. Because the visibility range is invariant according to illuminance, common logarithmic functions for 4 character sizes are used. The small difference between the postulated functions and the measured data verifies the accuracy of the functions.

• Journal of Powder Materials
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• v.18 no.6
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• pp.488-495
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• 2011

This study was performed to fabricate the porous titanium foam by space holder method using NaCl powder, and to evaluate the effect of NaCl volume fractions (33.3~66.6 vol.%) on the porosities, compressive strength, Young's modulus and permeability. For controlling pore size, CP titanium and NaCl particles were sieved to different size range of 70~150 ${\mu}m$ and 300~425 ${\mu}m$ respectively. NaCl of green Ti compact was removed in water followed by sintered at $1200^{\circ}C$ for 2 hours. Total porosities of titanium foam were in the range of 38-70%. Pore shape was a regular hexahedron similar that of NaCl shape. Porous Ti body showed that Young's modulus and compressive strength were in the range of 0.6-6 GPa and 8-127 MPa respectively. It showed that pore size and mechanical properties of Ti foams was controllable by NaCl size and volume fractions.

• Journal of the Korean Institute of Educational Facilities
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• v.7 no.3
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• pp.23-35
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• 2000

Today the supply of school sports halls for multi-functional use is absolutely insufficient in school facilities of Korea. For economical reasons and efficiency of use, a joint utilization of these halls by schools, sports clubs and other users should be strived for. This will lead, as a result, to a minimization overall in the demand for halls. Above all to satisfy this demand, the regulations of sports facilities suitable to the students' standards of play and physical conditions must be preceded in Korea. And a study on the architectural planning of this hall size for primary, middle and high school is needed. This study aims at establishing the range of optimum size of school sports hall in Korea by surveying and analyzing the regulations of sports facilities about clear height of hall, obstacle-free zone and court area in Japan, England, Germany and U.S.A. Therefore, this study will offer valuable basic data in planning the school sports hall.

• Journal of Fashion Business
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• v.16 no.1
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• pp.150-159
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• 2012

This study intend to analyze differences between 3D body scanning sizes and direct measurement sizes of same subjects. The subjects of study are female students of university in China. 3D data analyze as a 3D Body Measurement Soft System. The conclusion found is as below: In case of circumferences, error between direct-measurement size and 3D body scanning size is from 4.9mm to 62.2mm. The neck circumference size of directmeasurement is bigger than 3D body scanning size. The height error range is from 0.6mm to 51mm. Height of underbust, waist and hip are that direct-measurement sizes are higher than 3D body scanning sizes. Gap of width is from 3.8mm to 21.9mm. The gap range is too narrow relatively to others. Only direct-measurement size of neck width is wider than 3D body scanning size. Error range of length is from 0.3mm to 41.8mm. 3D body scanning sizes of lateral neck to waistline, upperarm length, arm length, neck shoulder point to breast point, shoulder center point to breast point, lateral shoulder to breast point are longer than direct-measurement sizes. They have a negative margin of error. I intend to set up same measurement point between direct-measurement and 3D body scanning but they have some errors because direct-measurement point is applied by a person. 3D body scanning measurement point is settled by automatic system. A measurement point of direct-measurement and 3D body scanning isn't unite. So we need to make a standard of setting up measurement points.

• Particle and aerosol research
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• v.5 no.2
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• pp.63-70
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• 2009

The size distribution and number concentration of atmospheric aerosol were measured and compared using APS 3321 and Dust Monitor 1.108. The particle size distribution and number concentration measured by two devices were also compared at a particle generation system of standard PSL and fly ash. The number concentration of atmospheric aerosol measured by APS was higher than that by Dust Monitor in particle size range of less than $3.0{\mu}m$, but there was good accordance between them in particle size range of over $3.0{\mu}m$. In the particle generation system of PSL and fly ash, different measurement results were shown because the particle concentration was higher than that of atmospheric aerosol. The number concentration measured by Dust Monitor was higher than that by APS in most particle size ranges. However, the peak concentration of PSL particles measured by Dust Monitor was lower than that by APS. The difference of the collection efficiency in a scrubber by APS and Dust Monitor measurement was less than 10%, but in the particle size of $1.5{\mu}m$, it was over 20%.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.78-89
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• 1996

Every mechanical component is fabricated with the variations in its size and shape, and the allowable range of the variation is specified by the tolerance in the design stage. Geometric tolerances specify the size or the thickness of each shape entity itself or its relative position and orientation with respect to datums. Since the range of shape variation can be represented by the variation of the coordinate system attached to the shape, the transformation matrix of the coordinate system would mathematically express the range of shape variation if the interval numbers are inserted for the elements of the transformation matrix. For the shape entity specified by the geometric tolerance with reference to datums, its range of variation can be also derived by propagating the transformation matrices composed of interval numbers. The propagation depends upon the order of precedence of datums.