• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.179-189
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• 1999

This study attempts to propose an evaluation considering the property of concrete pore which affects the deterioration of neutralization and the rebar resistance of concrete. Understanding pore property of concrete in using extent, for practical using of concrete manufacturing condition. basic quality property and durability estimation etc, the results of the experiment are as follows. 1) The result of analysis pore property of every specimen with the method of area ratio, in limitation of $10^{-6}{\sim}10^{-5}m$, the pore distribution ratio was maximum. It was high value as W/C was increased and the unit cement content was decreased. 2) In case of using admixture. the volume of pores was some increased as variation of mixing content. In high W/C range, it was very increased compared with plain concrete. 3) Concerned with compressive strength and volume of pores in hardened concrete, it is possible compressive strength estimation using the property of concrete pores. 4) Direct measurement of concrete pore property is difficult. the valuation of the dynamic modulus of elasticity using ultrasonic wave velocity was available. 5) Quantitatively evaluation of concrete structure durability by past result of pore distribution estimation, and it can be estimative scale of property study on the concrete materials.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.73-84
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• 1994

Using a model system that can compare the before and after of canal preparation in the same tooth, we measured the area of the cross section, and canal wall thickness of the distal portion of the mesial root of the mandibular molar, and compared the amount of reduction in the canal using hand flared preparation the Gates-Glidden drill flared preparation according to the changes in the MAF. The results were as follows. 1. After canal preparation, the canal wall thickness had no significant difference between the hand flared preparation and Gates-Glidden drill flared preparation. 2. The canal wall thickness, after canal preparation, there was no significant difference between the sizes of the MAF. 3. The area variation range of each cross section of root had no significant difference between MAF size and methods of canal preparation. 4. After canal preparation, the frequency of the canal wall thickness under 0.5mm showed 3.5mm below the furcation to be the most frequent with statistical significance(p<0.05). 2mm below the furcation and 5mm below the furcation followed but there was no statistical significance. 5. The danger zone of the mesial root of the mandibular molar seems to be around 3.5mm.

• Imaging Science in Dentistry
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• v.30 no.2
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• pp.101-108
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• 2000

Purpose : The effects of step numbers of copper wedge and exposure on the coefficient of determination (r²) of the conversion equation to Cu-equivalent image and on the Cu-equivalent value (mmCu) and it's coefficient of variation measured at each copper step and the mandibular premolar area were evaluated. Method: Digital image analyzing system consisted of scanner, personal computer, and a stepwedge with 10 steps of 0.03 mm copper in thickness as reference material was prepared for quantitative assessment of the bone mineral density. NIH image program was used for analyzing images. Results : The film having moderately high film density showed the discrepancy between the real thickness and the measured Cu-equivalent value of each copper step. The Cu-equivalent image was dependent on the determinational coefficient of the conversion equation than the coefficient of variance of the measured value. Conclusion : Obtaining conversion equation with high coefficient of determination and proper film exposure are supposed to be neccessary for quantitative assessment of bone density. Multiple steps in the range of the corresponding copper thickness to the bone density of the area to be measured should be prepared.

• Structural Engineering and Mechanics
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• v.30 no.3
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• pp.263-278
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• 2008

Structural pipe-in-pipe cross-sections have significant potential for application in offshore oil and gas production systems because of their property that combines insulation performance with structural strength in an integrated way. Such cross-sections comprise inner and outer thin walled pipes with the annulus between them fully filled by a selectable thick filler material to impart an appropriate combination of properties. Structural pipe-in-pipe cross-sections can exhibit several different collapse mechanisms and the basis of the preferential occurrence of one over others is of interest. This paper presents an elastic analyses of a structural pipe-in-pipe cross-section when subjected to external hydrostatic pressure. It formulates and solves the static and elastic buckling problem using the variational principle of minimum potential energy. The paper also investigates a simplified formulation of the problem where the outer pipe and its contact with the filler material is considered as a 'pipe on an elastic foundation'. Results are presented to show the variation of elastic buckling pressure with the relative elastic modulus of the filler and pipe materials, the filler thickness and the thicknesses of the inner and outer pipes. The range of applicability of the simplified 'pipe on an elastic foundation' analysis is also presented. A brief review of the types of materials that could be used as the filler is combined with the results of the analysis to draw conclusions about elastic buckling behaviour of structural pipe-in-pipe cross-sections.

• Computers and Concrete
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• v.9 no.2
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• pp.133-151
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• 2012

This paper presents an analytical procedure for the analysis of high strength steel fiber reinforced concrete members considering the cracking effect in the serviceability loading range. Modifications to a previously proposed formula for the effective moment of inertia are presented. Shear deformation effect is also taken into account in the analysis, and the variation of shear stiffness in the cracked regions of members has been considered by reduced shear stiffness model. The effect of steel fibers on the behavior of reinforced concrete members have been investigated by the developed computer program based on the aforementioned procedure. The inclusion of steel fibers into high strength concrete beams and columns enhances the effective moment of inertia and consequently reduces the deflection reinforced concrete members. The contribution of the shear deformation to the total vertical deflection of the beams is found to be lower for beams with fibers than that of beams with no fibers. Verification of the proposed procedure has been confirmed from series of reinforced concrete beam and column tests available in the literature. The analytical procedure can provide an accurate and efficient prediction of deflections of high strength steel fiber reinforced concrete members due to cracking under service loads. This procedure also forms the basis for the three dimensional analysis of frames with steel fiber reinforced concrete members.

• The Korean Journal of Ecology
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• v.18 no.3
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• pp.353-366
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• 1995

To study the relationship between the germination response and geographical distribution, the seeds of Rumex acetocella were collected from nine sites (Taegwallyong, Alps lodge, Kans'ong, Sokch'o, Chumunjin, Suwon, Taechon, Sukgok, Mokpo) of different latitudes and altitudes. The populations of Rumex acetocella were subdivided into four groups based on the characteristics of the seed germination. The first group of Rumex acetocella (Taegwallyong, Alps lodge) germinated rapidly in early spring, the second group (Suwon, Teachon) in late summer through early autumn, and the third group(Sukgok, Mokpo) slowly in late autuman with various conditions. The thermal time values needed for the germination rate of 10% to 60% for these three groups indicated that the germination rate was low at the lower latitude, while it was increased as the latitude elevated. The population of the fouth group (Kansong, Sokcho, Chumunjin) showed the narrow optimum temperature range of germination response and the highest thermal time value to germinate 10% to 30% of seeds. The seeds in the high latitude region with relatively mild winter germinated synchronously in early autumn. These different germination responses of Rumex acetocella to geographic variations were thought to be an ecological strategy to survive in different environmental conditions.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.269-271
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• 2002

It is reported that exposure for the patient and the medical staff from IVR is large. Direct measurement of patient exposure is difficult, since the measurement disturbs reading of images. The fluorescence glass-dosimeter system consisting of small-size glass chips is developed in recent years. Owing to its small size and physical characteristics, direct monitoring of surface dose may be feasible. The dose measurement for patient and medical staff during head interventional radiology (IVR) examinations was tried by using the fluorescence glass-dosimeter system. A dose response of the glass dosimeter is almost linear in large dose range but its energy dependency is high. About 20% variation of sensitivity was observed in the effective energy of 45-60keV which was used in IVR. In spite of this shortcoming, the fluorescence glass-dosimeter system is a convenient means for a dose monitoring during IVR performance.

• Restorative Dentistry and Endodontics
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• v.26 no.2
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• pp.127-133
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• 2001

There are several factors affecting the effectiveness of polymerization of the esthetic restorative materials. Among those factors, the initiator. camphoroquinone has the unique characteristic. of which the light sensitivity is very dependent on the wavelength of blue light. Camphoroquinone shows the most light absorption ability in the wavelength range of 470nm. So most of clinically used light curing systems adopt this phenomenon as their polymerization mechanism. The most popular way of light curing system is standard 40 second curing. But the problem of standard curing technique shows the rapid increase of resin viscosity followed by the acceleration of polymerization and the limited resin flow, resulted in reduction of the physicalproperty of restoration by retained stress. The object of this study was to verify the effects of narrow-banded wavelength on the microhardness of the esthetic restorative materials. a composite resin and a compomer, using filters which have peak wave length of 430nm, 450nm, 470nm, respectively. The results were as follows: 1. All the experimental groups showed lower hardness value than the control group. 2. In DyractAP, the hardness value by wavelength showed the same changing pattern on both upper and lower surfaces. 3. In DenFil, the hardness value by wavelength showed different changing pattern on upper and lower surfaces. 4. The hardness ratio showed similar pattern to the hardness variation of lower surface. but there was no significant difference between measurement in 10 minutes and 3 days later, besides the increase of hardness value.

• The Research Journal of the Costume Culture
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• v.19 no.4
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• pp.661-673
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• 2011

This study aimed to identify the intrinsic characteristics of camouflage patterns by reviewing their origin, transitions and types from a theoretical background and analyzing their forms of expression in contemporary fashion. For a literature review and an empirical analysis of the camouflage patterns used in contemporary fashion, the study referred to domestic and foreign fashion magazines published between 2000 S/S and 2010 S/S, including Gap Press, Fashion News, Vogue and Harper's Bazaar, and other related data available on the internet. The findings of this study show that the forms of camouflage patterns used in contemporary fashion can be divided into four types: abstract patterns, plant patterns of flowers or leaves, animal patterns and dotted patterns. In terms of coloration, the camouflage patterns work to refresh the design, breaking from the image of military uniforms through the use of a wide range of color variation and combinations as well as the traditional camouflage colors based on khaki and beige. In terms of expression, most of them utilize printing. However, other techniques of expression, such as embroidery, beading, knitting, and collages are used to emphasize the beauty of handcrafted decorations along with the aesthetic value of reliefs. Through these tendencies of expression, the characteristics of contemporary fashion using camouflage are explained with an emphasis on feminine beauty, the expression of neutrality, and the use as decorative factors.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.345-353
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• 2000

Carbon nanofibers were prepared from the decomposition of various carbon-containing gases over pure Ni, pure Fe and their alloys with Cu. They yields, properties, and structure of carbon nanofibers obtained from the various reaction conditions were analyzed. Type of reacting gas, reaction temperature and catalyst composition were changed as the reaction variable. With Ni-Cu catalysts, the maximum yields of carbon nanofibers were obtained at temperatures between 550 and 650$^{\circ}C$ according to the reacting gas mixtures of C2H2-H2, C2H4-H2 and C3H8-H2, and the surface areas of the carbon nanofibers produced were 20∼350㎡/g. In the case of CO-H2 mixture, the rapid deposition of carbon nanofibers occurred with Fe-Cu catalyst and the maximum yield were obtained around 550$^{\circ}C$ with the range of surface areas of 140∼170㎡/g. The electrical resistivity of carbon nanofiber regarded as the key property of filler for the application of electromagnetic interference shielding was very sensitive to the type of reactant gas and the catalyst composition ranging 0.07∼1.5Ωcm at a pressure of 10000 psi, and the resistivity of carbon nanofibers produced over pure nickel catalyst were lower than those over alloy catalysts. SEM observation showed that the carbon nanofibers produced had the diameters ranging 20∼300 nm and the straight structure of carbon nanofibers changed into the twisted or helical conformation by the variation of reacting gas and catalyst composition.