• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.2937-2947
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• 2024

The Republic of Korea is performing independent national inspections under the IAEA's State System of Accounting for and Control (SSAC), and developing an evaluation methodology for the material unaccounted for (MUF) to reinforce capabilities with the purpose of assessment for the accounting system of the facility handling bulk nuclear materials. In relation to this, a new approach for MUF evaluation was proposed in this study based on the guide to the expression of uncertainty in measurement (GUM). Both the conventional MUF evaluation method and the GUM method were applied to a hypothetical list of inventory items including material balance. Considering the ease of uncertainty propagation according to the GUM, it was assumed that independent uncertainty factors correspond to random factors, while correlated uncertainty factors correspond to systematic factors. The total MUF uncertainties were similar for both methods; however, it was verified that some uncertainties were affected by the measurement procedure in the GUM method. Furthermore, the GUM method was found to be more conducive to conducting a factor analysis for the MUF uncertainty. It was therefore concluded that application of the GUM approach could be beneficial in cases of national safeguard inspections where factor analysis is required for MUF assessment.

• Restorative Dentistry and Endodontics
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• v.49 no.3
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• pp.23.1-23.10
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• 2024

Objectives: Previous in vitro studies determined the whitening effects of bleaching products on stained resin composite surfaces. This in vitro study aimed to verify the effectiveness of a whitening system on composite resin previously subjected to pigmentation, specifically examining the depth of whitening effectiveness within the material structure. Materials and Methods: A commercially available nano-filled composite resin was used. Specimens were stained using a coffee-based solution and a 10% carbamide peroxide-based gel was employed as the whitening agent. The pigment's penetration and the effect of the bleaching gel were evaluated by measuring color (CieLab values) from the outer edge to the inner part of the specimens. Color measurements were taken at 14 points, starting from 0.1 mm from the external perimeter up to 3.0 mm. Results: Analysis of variance tests showed a statistically significant difference between the Control Group (CG), Pigmentation Group, and Whitening Group. The whitening agent was effective up to 1.5 mm in depth, with Whiteness index (W) values not statistically different from those of CG up to 0.5 mm in depth. Conclusions: Whitening agents on nano-filled resin composite previously pigmented appear effective in restoring the W to values similar to the original, particularly in the superficial layers of the sample.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.243-254
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• 2002

For the purpose of evaluating the biocompatability of 3 kinds of metallic materials frequently used in pediatric dentistry (stainless steel crown, orthodontic band, orthodontic wire), cellular and molecular studies, including cell growth and proliferation, screening of cell death with determination of types whether necrosis or apoptosis and changes in expressions of related signaling molecules were examined, using cultured human gingival fibroblasts (HGF-1), HGF-1 was cultured in Dulbecco's modified Eagle's medium. among which the 3rd to 6th generations of HGF-1 were used. The specimen were divided into stainless steel crown (R), band (B) and wire (W). The immunocytochemical study was done for the detection of anti-PCNA (proliferating cell nuclear antigen) labeling. With extracted protein, western blot was done for the detection of ERK1/2, JNK, and p38, using individual antibodies. Cultured cells proliferated, remarkably till 7 day and slightly at 11 day. There was no statistical significance in the counts of proliferating HGF-1 between control and experimental groups (p>0.05). Relative growth rates were no statistically significant difference between control and experimental groups (p>0.05). PCNA labeling indexes showing similar patterns in control and experimental groups. The expressions of ERK1 and ERK2, p38 were similar in control and experimental groups. The expression of JNK increased at 1st day, slightly decreased at 4th day and markedly increased at 7th and 11 day. Although the patterns of control and experimental groups were similar, the increased expressions of JNK at late period suggest a possible stress due to inhibited cell growth and proliferation, and worse culture condition. Conclusively, the 3 kinds of metal specimens used in this study did not induce cellular and molecular hazards during short term culture of HGF-1. But, for the better clinical stability, the establishment of long period culture and animal experiment was thought necessary.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.281-295
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• 2017

We determined chemical compositions like abundance of major and trace elements, Sr and Nd isotope compositions for two tektites from the Thailand and Vietnam. Their chemical compositions are similar to each other, and seem to be similar to those of PAAS (Post Archean Australian Shale) rather than upper continental crust. In particular, primitive mantle-normalized spider diagrams and chondrite-normalized REE patterns for two tektites are the same, suggesting that they might be derived from the same source material. The $^{87}Sr/^{86}Sr$ and $^{143}Nd/^{144}Nd$ ratios from Thailand tektite are $0.718870{\pm}0.000008(2{\sigma}_m)$ and $0.512024{\pm}0.000012(2{\sigma}_m)$, respectively, and those from Vietnam are $0.717022{\pm}0.000008(2{\sigma}_m)$ and $0.511986{\pm}0.000013(2{\sigma}_m)$, respectively. The $^{87}Sr/^{86}Sr$ and $^{143}Nd/^{144}Nd$ ratios from Thailand tektite are slightly enriched than those of Vietnam tektite. $^{87}Sr/^{86}Sr$ ratios from the Vietnam and Thai tektites were plotted on the range of Australasian tektites reported previously. $^{143}Nd/^{144}Nd$ ratio of Vietnam tektite from this study was lower than the range of $^{143}Nd/^{144}Nd$ ratio from the Australasian tektite reported previously whereas that of Thai tektite was included in the range of $^{143}Nd/^{144}Nd$ ratio from the Australasian tektite. The geochemical characteristics from two tektites in this study indicate that they may be derived from the very similar source materials.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.408-419
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• 2007

In the child, it is very important that he/she will have the ability to suppress aesthetic restorative materials of secondary caries. With the representative preventive material against caries, the importance of fluoride is more emphasized. This study examined the differences in fluoride release and re-uptake among some restorative materials, following a treatment of APF gel and fluoride varnish. The surface roughness was observed under scanning electron microscope. Studying this will provide for the research to find effective restorative materials and fluoride type in tooth caries prevention. It is applied from presence at a clinic that restorative materials are resin, flowable resin, compomer and glass ionomer. Fluoride release was measured at 24-hour intervals for 7 days, 3-day intervals from 8th to 38th day using an ion-selective electrode and analyzer. Then, the materials were treated with the fluoride gel and fluoride varnish respectively, fluoride release was measured and specimens were evaluated under scanning electron microscope for 4 weeks. It was concluded that 1. Fluoride was released for 38 days from restorative materials under 1 ppm in case of flowable resin, 1-2 ppm in compomer and 2-8 ppm in glass ionomer, a few of fluoride was released after 45 days 2. Fluoride has more releasing after application of APF gel than fluoride varnish. Fluoride re-uptake was observed under 0.6-0.2 ppm in fluoride varnish and 0.6-2.6 ppm in APF gel after starting the procedure one day(p<0.05). For the remaining 4 weeks, they demonstrated a similar release. 3. Specimens were evaluated under scanning electron microscope. Applied fluoride in the experimental group surface was rougher than the control group that did not receive fluoride application. Fluoride varnish group had a smoother surface than both the APF gel group and the varnish APF gel group that received a fluoride application.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.908-913
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• 2001

Paper sludge Ash (PA) and Fly Ash (FA) wastes are usually land-filled for reclamation or substituted for cements as a resource. It could also offer some advantages when they are substituted for clay to preserve the environment. To recycle those wastes, the sintered specimen made of PA-FA-Clay system were examined to find the microstructure and physical properties. The ratio of clay to wastes was fixed as 30:70 by wt%, while PA to FA within waste portion were varied in the range of $1:6{\sim}7:0$. Those specimens were fired in $1150{\sim}1350^{\circ}C$. It was found that the relative density of sintered specimen was increased with amount of PA added at low sintering temperature (i.e, $1150{\sim}1200^{\circ}C$). This is due to increased amount of liquid during sintering. It is shown, however that at high sintering temperature ($1250{\sim}1350^{\circ}C$), the relative density of specimens was decreased with amount of PA added. This is because of overfiring phenomenon which may be able to induce an inhomogeneous microstructure and increased porosity. The mechanical properties of sintered specimen were depended upon the homogeneity of microstructure in accordance with SEM (Scanning Electron Microscopy) and pore size distribution analysis. For example, the compressive strength of 10PA-60FA-30Clay specimen sintered at $1225^{\circ}C$ was twice higher than that of 70PA-30Clay specimen even thought the relative density of those specimen was similar. This decreased strength of 70PA-30Clay specimen appears to be an inhomogeneity of microstructure due to overfiring.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.230-237
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• 2010

A homologous series of linear liquid crystal dimers, ${\alpha},{\omega}$-bis(4-nitroazobenzene-4'-carbonyloxy)alkanes (NATWESn, n = 2~8, 10, the number of methylene units in the spacer) have been synthesized, and the thermal behavior of the series has been investigated. All the dimers formed enantiotropic nematic phases. The nematic-isotropic transition temperatures of the dimers and their entropy variation at the phase transition showed a large odd-even effect as a function of n. This behavior was rationalized in terms of the change in the average shape of the spacer on varing the parity of the spacer. The thermal stability and degree of order in the nematic phase and the magnitude of the odd-even effect of NATWESn were very similar to those of the corresponding ether compounds, while they were significantly different from those of the monomesogenic compounds, 4-{4'-(nitrophenylazo)phenoxy}alkanoyl chlorides and the side-chain liquid-crystalline polymers, the poly[1-{4-(4'-nitrophenylazo) phenoxycarbonylalkanoyloxy}ethylene]s. The results were discussed in terms of the 'irtual trimer model'by Imrie.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.265-269
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• 2015

Chlorella vulgaris (C. vulgaris) is a spherical unicellular green algae and the diameter ranges from 2 to $10{\mu}m$. C. vulgaris possess nutritional excellence because it contains various functional materials including high protein contents, chlorophyll, carotenoid, and chlorella growth factor (CGF). In order to study effects of mutagen, ethyl methane sulphonate (EMS) was used as a chemical mutagen and some mutants could be obtained. We named 2 type mutants as E14 and E24 obtained after treating with EMS. In the cell growth, growth patterns of mutants were similar to those of the wild type. Chlorophyll contents of E14 and E24 increased up to 99 and 52%, respectively compared to those of the wild type. The carotenoid content of E14 increased to 7%, but the value of E24 decreased 5% compared to that of the wild type. For the lipid contents E24 increased to 23%, while E14 decreased 12% when compared to those of the wild type. As a result, there is no difference between the mutants and wild type in the cell growth, but considering that mutants contains more physiological materials than those of the wild type, we can expect the mutants of C. vulgaris could be used as important high added-value materials.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.333-343
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• 2011

The yellow poplar is an appropriate species for the age of low carbon green growth, because its absorption rates of ozone is greatly excellent, and also the absorption rates of carbon dioxide causing climate changes is very remarkable. The yellow poplar, which is a kind of rapid growth tree, shows a lack of performance as a structural member, however, it is suitable to use a variety of purposes like furniture materials, interior materials, plywood materials, and so on. In this study, the structural size skin-timbers were made by using the yellow poplar, and the compressive capacity was evaluated, also the numerical model was developed for the various uses. The rectangular shape skin-timber presented a good performance by showing 56.3% residual strength about the solid material. In case of the cylinder shape skin-timber showed a possibility to use diversely as a furniture material, as well as a structural uses, because almost 50% compressive capacity of material even though its residual area rates was 25%. Both rectangular shape and the cylinder shape represented that 'Brooming or end rolling' were the major failure mode, and partly splitting failure mode. The compressive capacity of the rectangular shape which residual area rates was large was higher than the cylinder shape, but it did not show statistical significance about the compressive capacity between them. Thus, it will be possible to use them mixed for a convenience of users. The result of the numerical analysis model was quite similar to actual test of the compressive capacity. Therefore, the yellow poplar can be utilized in the development of various uses by applying numerical analysis model about a variety of shapes and dimensions.

• Korean Journal of Environmental Agriculture
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• v.32 no.4
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• pp.338-342
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• 2013

BACKGROUND: Two Field tests were conducted at Buan and Yangpyung in 2012 and 2013 to confirm controlling effect of mulberry popcorn disease and mulberry Sucker pests which are becoming serious in mass cultivation area of eco-friendly farming mulberry. METHODS AND RESULTS: As the treatments, 4 Natural products and 3 microbials were applied and 4 mulching materials were used. On the prevent effect of mulberry popcorn disease(Sclerotinia shiraiana) by using mulching materials, nonwoven fabric mulching showed worse effect than non-mulched treatment plot. Moreover, rice straw mulching showed significantly worse effect compare to nonwoven fabric and herb mulching treatments. Natural plant extracts and microbials showed 40~65% control value in 2013, which is little bit worse than 2012 results. On the control effect of mulberry Sucker(Amomoneura mori), organic products which combined with neem, sophora and derris showed excellent result as similar control level of Thiophanate-methyl. It means the chemical products can be replaced with organic product. CONCLUSION(S): According to the 2 years studied results, integrate eco-friendly farming measures are recommended for control of mulberry popcorn disease, because any single method is seemed not sufficient enough. However, natural plant extracts mixture is recommended as a product to control of mulberry Sucker.