• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.111-122
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• 2021

Purpose: The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. Materials and Methods: Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900℃ using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. One-way ANOVA, Tukey HSD test were performed (α = 0.05). Results: There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. Conclusion: Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

• Composites Research
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• v.36 no.6
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• pp.435-440
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• 2023

This study aimed to enhance the thermal conductivity of B₄C/Al composite materials, commonly used in transport/storage containers for spent nuclear fuel, by incorporating both boron carbide (B₄C) and cubic boron nitride(cBN) as reinforcing agents in an aluminum (Al) matrix. The composite materials were successfully manufactured through a stir casting process and practical neutron-absorbing materials were obtained by rolling the fabricated composite ingot. The evaluation of the thermal conductivity of the fabricated composites was carried out because thermal conductivity is critical for neutron absorbing materials. The thermal conductivity measurement results indicated an approximately 3% increase in thermal conductivity under the same volume fraction when compared to composite materials using only B₄C particles. Through neutron absorption cross-sectional area calculations, it was confirmed that the neutron absorption capability decreased to a negligible level. Based on the findings of this study, new design approaches for neutron absorption materials are proposed, contributing to the development of high-performance transport/storage containers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.27-34
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• 2024

This study was conducted to examine the feasibility of using Fe-activated wood-derived biochar as a conductive filler for manufacturing cement-based strain sensor. To evaluate the compressive and electrical properties of cement composite with 3% Fe-activated biochar, three cubic specimens of size 50 x 50 x 50mm³ and three prismatic cement-based sensors of size 40 x 40 x 80mm³ were prepared respectively. The four-probe method of electrical resistance measurement was used for cement-based sensors. For cement-based sensors with FE-activated biochar, the conductive performance such as electrical resistance and impedance under different water content and repeated compression was investigated. Results showed that the fractional changes in the DC electrical resistivity of cement-based sensors increase with increasing time and the maximum fractional changes in the resistivity decrease with increasing the moisture contents during 900s. At moisture content of 7.5% range, the conductive performance of cement composite including 3% Fe-activated biochar as a conductive filler showed the most stable, while the strain detection ability tended to decrease somewhat as the repeated compressive stress increased between repeated compressive strain and fractional change in resistivity (FCR).

• Journal of Sasang Constitutional Medicine
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• v.10 no.1
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• pp.101-142
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• 1998

1. Objects The base of classification of Sasang Constitution was the different congenital formation of organs such as lungs, spleen, liver, kidneys, and it was expanded from the viscera region of lungs, spleen, liver, kidneys to the body shape of trunk. The researched about body shape of Sasang Constitution have had points of issues which derived by measurement with hands. But this study was measured the characteristics of body shape putting in importance of anatomical position with the computerized 3-Dimension scanner, which minimized the errors of measurement, and it was abled the cubic measurement such as volume, area of cross section as well as round length. 2. Materials & Method The examinee was healthy male 40 persons and female 20 persons from 20's to 40's, who was diagnosed by the specialist of Sasang Constitutional Medicine. The body shape was measured round length, area of cross section, and volume of 31 anatomical points and the 25 hypothesis with the Rapid 3D Color Scanner Model 3030 RGB/PS. And the characteristics of each constitution's body shape was derived. 3. Results & Concousion In female, Taeumin had the largest trunk and Soeumin had the smallest trunk compared to other constitution, but Soyangin had only the smallest neck. Soeumin has the smallest round length of nipple and the $CV_{12}$, and Soyangin has the smallest breadth of ASIS. Soyangin had the smallest volume from thyroid bone to the highest points of armpits and from sternum to nipple. Taeumin had the largest volume from sternum to the $CV_{12}$ and from sternum to xiphoid process. In male, Taeumin had the largest trunk and Soeumin had the smallest trunk from the level of thyroid bone to ASIS. Soyangin has the longest distance and Soeumin has the shortest distance from nipple to the lowest of breast. Taeumin had the largest volume of trunk and Soeumin had the smallest volume of trunk. In the ration of four-Cho, Taeumin had the longest distance from the highest points of armpits to nipple and Soyangin had the shortest distance of that. Soyangin had the smallest ratio of the height of upper middle cho. Soeumin had the smallest ratio from the $CV_{12}$ to navel among trunk. In the correlation among the four Cho, Taeumin had the negative correlation between the Upper-Cho and the Lower-Middle-Cho significantly.

• Journal of Environmental Impact Assessment
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• v.28 no.5
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• pp.492-506
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• 2019

Heavy metal contaminants in the shooting range are mostly present in a warhead circle or a metal fragment present as a particle, these fine metal particles are weathered for a long period of time is very likely that the surface is present as an oxide or carbon oxide. In particular, lead which is a representative contaminant in the shooting range soil, is present as more fine particles because it increases the softness and is stretched well. Therefore, by physical washing experiment, we conducted a degree analysis, concentration of heavy metals by cubic diameter, composition analysis of metallic substances, and assessment of applicability of gravity, magnetism and floating selection. The experimental results FESEM analysis and the measurement results lead to the micro-balance was confirmed thatthe weight goes outless than the soil ofthe same size in a thinly sliced and side-shaped structure according to the dull characteristics it was confirmed that the high specific gravity applicability. In addition, the remediation efficiency evaluation results using a hydrocyclone applied to this showed a cumulative remediation efficiency of 71%,twice 80%, 3 times 91%. On the other hand, magnetic sifting showed a low efficiency of 17%,floating selection -35mesh (0.5mm)target soil showed a relatively high efficiency to 39% -10mesh (2mm) efficiency was only 16%. The target treatment diameter of soil washing should be 2mm to 0.075mm, which is applied to the actual equipment by adding an additional input classification, which would require management as additional installation costs and processes are constructed. As a result, it is found that the soilremediation of shooting range can be separately according to the size of the warhead. The size is larger than the gravel diameter to most 5.56mm, so it is possible to select a specific gravity using a high gravity. However, the contaminants present in the metal fragments were found to be processed by separating using a hydrocyclone of the soil washing according to the weight is less than the soil of the same particle size in a thinly fragmented structure.