• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.607-616
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• 2022

Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.

• Analytical Science and Technology
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• v.22 no.4
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• pp.285-292
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• 2009

It has been observed that, after long term storage, some ammunitions are misfired by tamping (combustionstopping) due to aging of the chemicals loaded in the ammunitions. Used in ammunitions are percussion powder which provides the initial energy, igniter which ignites the percussion powder, and a delay system that delays the combustion for a period of time. The percussion powder is loaded first, followed by the igniter and then the delay system, and the ammunitions explode by the energy being transferred in the same order. Tamping occurs by combustion-stopping of the igniter or insufficient energy transfer from the igniter to the delay system or the combustion-stopping of the delay system, which are suspected to be caused by low purity of the components, inappropriate mixing ratio, size distribution of particulate components, type of the binder, blending method, hydrolysis by the humidity penetrated during the long term storage, and chemical changes of the components by high temperature. Goal of this study is to find the causes of the combustion-stopping of the igniter and the delay system of the ammunitions after long term storage. In this study, a method was developed for testing of the combustion-stopping, and the size distributions of the particulate components were analyzed with field-flow fractionation (FFF), and then the mechanism of chemical change during long term storage was investigated by thermal analysis (differential scanning calorimetry), XRD (X-ray diffractometry), and XPS (X-ray photoelectron spectroscopy). For the ignition system, M (metal)-O (oxygen) and M-OH peaks were observed at the oxygen's 1s position in the XPS spectrum. It was also found by XRD that $Fe_3O_4$ was produced. Thus it can be concluded that the combustion-stopping is caused by reduction in energy due to oxidation of the igniter.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.3
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• pp.189-196
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• 2022

Plasma refers to an ionized gas that is often referred to as "the fourth phase of matter", following solid, liquid, and gas. Plasma has traditionally been utilized for industrial applications such as welding and neon signs, but its promise in biomedical fields such as cancer treatment and dermatology has lately been recognized. Indeed, due to its beneficial effects in promoting collagen production, improving skin tone, and eliminating harmful bacteria in the skin, plasma treatment constitutes an important target for dermatological research. In this study, a plasma device for cosmetic manufacturing based on nitrogen, the main component of the atmosphere, was designed and assembled. Moreover, nitric oxide (NO) was selected since is easier to follow and evaluate than other nitrogen plasma active species, and its contents were measured to perform a quantitative and qualitative evaluation of plasma. First, an injection method, using different proximities labeled "sinking" and "non sinking" treatments, was performed to test the most efficient plasma treatment method. As a result, it was observed that the formulation obtained by a non sinking treatment was more effective. Furthermore, toner and ampoule were selected as cosmetics formulations, and the characteristics of the formulation and changes in the injected plasma state were observed. In both formulations, the successful injection of NO plasma was 2 times higher in toner formulation than ampoule formulation, and it gradually decreased with time, having dissipated after a week. It was confirmed that the nitrogen plasma used did not affect the stability of the toner and ampoule formulations at low temperature (4 ℃), room temperature (25 ℃), and high temperature (37 ℃ and 50 ℃) conditions. The results of this study demonstrate the potential of plasma cosmetics and highlight the importance of securing the stability of the injected plasma.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.37-49
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• 1998

The specimens used were Ag-25 Pd-15 Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age- hardening characteristics of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing. X-ray diffraction and electron microscope observations, electrical resistance, ergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, i.e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the $L1_0$ type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage II, decomposition of the ${\alpha}$ solid solution to a PdCu ordered phase($L1_0$ type) and an Ag-rich ${\alpha}2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was conclued that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipetation procedure was ${\alpha}{\to}{\alpha}+{\alpha}_2+PdCu {\to}{\alpha}_1+{\alpha}_2+PdCu$ at Pd/Cu = 1.7 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.152-161
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• 2020

This study determined the removal ofrates for three types of pesticides which were spiked from Chonggak radish during the preparation of chonggak kimchi. When Chonggak radish (leaves) were brined with 10% salt solution and rinsed with water, the removal rate of the three pesticides was 43.8%, 41.9% and 89.8% for diazinon, diniconazole and dimethomorph, respectively. When Chonggak kimchi (leaves) were prepared and fermented for 4 weeks at 4℃, the removal rate of the three pesticides was 82.4%, 77.2% and 98.9% for diazinon, diniconazole and dimethomorph, respectively. Pesticide residues in chonggak radish (roots) were removed by up to 54.7-85.1% of initial concentration through brining and washing. During the fermentation of chonggak kimchi (roots) for 4 weeks at 4℃, the amount of pesticide residues was decreased by 94.0%, 91.8% and 90.0% of initial concentration for diazinon, diniconazole and dimethomorph, respectively. The highest relative removal rate by percentage for the three pesticides asreached 66.5% by salting chonggak radish (leaves). On the other hand, the highest relative removal rate by percentage of pesticides was shown during fermentation, reaching 51.8% and 55.8% for diazinon and diniconazole, respectively, in Chonggak kimchi (roots). As a result of examining the differences ofbetween the three pesticide removal rates rates according to temperature while fermentedduring fermentation of Chonggak kimchi with three pesticides for 4 weeks at 0℃ and 4℃, diazinon pesticide removal was has a high pesticide removal rate of 2.7-10.8% from fermented Chonggak kimchi (roots) at 4℃ compared to 0℃. In the other pesticides, the difference in removal rate of the pesticideresidual pesticides residues by aging temperature was found to be insignificant.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.21-35
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• 1997

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-20Pd-20Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electic furace and centrifugal casting machine in Ar atmoshpere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age-hardening characteristics of the small Au-containing Ag-pPd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, emergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, I. e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the Llo type face centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affedted by the Cu concentration. In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase(L1o type) and an Agrich ${\alpha}2$ phase occurred and a discontiunous precipitation occurred at the grain boundary. Form the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}\to{\alpha}+{\alpha}2+PdCu\to{\alpha}1+{\alpha}2+PdCu$ at Pd/Cu = 1 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.12-27
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• 2023

In this study, among the construction-type parks in Gangdong-gu, targeting parks with high environmental and ecological value located on the urban green axis, a plan was prepared for the ecological renewal of urban parks, and a design that applied to them was proposed. The renewal target site was selected by analyzing the general condition of Gangdong-gu and urban parks, the land use and green area ratio, park green area, and the green axis of Gangdong-gu. Gangdong-gu has 54 parks, including 2 neighborhood parks and 52 children's parks. In the first stage of the current status review, 17 parks were extracted through locational value analysis, such as location and adjacency to the natural axis and green axis. In the second stage, eight parks were selected among the first-stage extraction parks based on the ratio of green spaces and open spaces within each park service area. In the third stage, two of the second stage extraction parks were selected based on whether the legal standard of the park area was met, and in the fourth stage, one of the third stage extraction parks was selected through an aging survey of the park. As for the urban ecological status of the renewal target site, the status of land use in the aspect of entropy reduction, the status of soil cover in the aspect of water circulation, and the status of planting structure in the aspect of biodiversity were investigated. As for the status of the three renewal sites, the green area was insufficient at 18.3-45.3%, and the facility area was 54.7%-81.7%, which was judged to have low urban temperature reduction effects. The impervious pavement area accounted for 34.5% to 48.9% of the park area, accounting for most of the facility area, and it was judged that the water circulation function was insufficient. The planting structure consisted of a single layer and a double layer structure, and although the tree layer was good, the lower vegetation was poor, and there was no planting site of edible plants or large hardwood trees, so the biodiversity was low. After the ecological renewal design of Seonrin Children's Park, Dangmal Children's Park, and Saemmul Children's Park, which were selected as the renewal targets in this study, the ecological area ratio of each park increased by 1.4 to 3 times than before the renewal. If the urban parks located on the urban green axis are examined from the perspective of the urban ecosystem and renewed ecologically, it is judged that the expected effect will be high in reducing entropy, improving water circulation, and laying the foundation for biodiversity in terms of the urban ecosystem.

• Food Science of Animal Resources
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• v.28 no.3
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• pp.283-288
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• 2008

Eight subprimal cuts purchased from the branded Hanwoo beef of 3 quality grades ($1^{++}$, $1^+$, 1) at 13 stores were evaluated the tenderness using Warner-Bratzler shear (WBS). The beef frequency ratio (%) depending on postmortem aging periods were investigated. The 37.5 (quality grade $1^{++}$), 45.8 (quality grade $1^+$), and 36.4% (quality grade $1^{++}$) of branded beef were aged for < 7 d, 26.6 (quality grade $1^{++}$), 47.2 (quality grade $1^+$) and 36.4% (quality grade 1) were aged for $7{\sim}13$ d, and 31.3 (quality grade $1^+$), 4.2 (quality grade $1^+$) and 25.8% (quality grade $1^+$) were aged for 14 to 20 d. The temperature of cold room in stores was ranged average 2.27 to $2.42^{\circ}C$. WBS values for ansimsal (tenderloin), witdngsimsal (ribeye), cheggtsal (shortloin), doganisal (knuckle) and moongchisatae (hind shank) from branded Hanwoo beef of quality grade $1^{++}$ were tender than those from branded Hanwoo beef of quality grade 1 (p<0.05). WBS values for ansimsal (tenderloin) were 2.56 (quality grade $1^{++}$), 2.76 (quality grade $1^+$) and 3.10 kg (quality grade 1), respectively, and those for doganisal (knuckle, quality grade $1^{++}$), hongdukesal (eye of round, quality grade $1^+$) and bosupsal (top sirloin, quality grade 1) were 4.76, 4.96 and 5.66kg, respectively (p<0.05). The frequency ratio (%) of WBS < 3.9 kg in the all subprimal cuts from branded Hanwoo beef of quality grade $1^{++}$ were 100 [ansimsal (tenderloin) and cheggtsal (shortloin)], 87.5 [witdngsimsal (ribeye)] and 62.5% [bosupsal (top sirloin)], whereas that of WBS > 4.6 kg were 50.0% [hongdukesal (eye of round) and doganisal (knuckle)]. The frequency ratio of WBS < 3.9 kg in the an subprimal cuts of quality grade $1^+$ were 100 [ansimsal (tenderloin) and witdngsimsal (ribeye)] and 44.4% [cheggtsal (shortloin) and gurisal (chuck tender)], whereas that of WBS > 4.6 kg were 66.7 [hongdukesal (eye of round)], 55.6 [doganisal (knuckle)] and 44.4% [bosupsal (top sirloin)]. The frequency ratio (%) of WBS < 3.9 kg in the all subprimal cuts of quality grade 1 were 88.9 [ansimsal (tenderloin)], 62.5 [cheggtsal (shortloin)] and 44.4% [witdngsimsal (ribeye)], whereas that of WBS > 4.6 kg were 100.0 [doganisal (knuckle)] 62.7 [hongdukesal (eye of round)], 62.5 [gurisal (chuck tender)] and 55.6% [moongchisatae (hind shank)]. From these results, subprimal cuts from branded Hanwoo beef were marketed with short aging periods and high frequency ratio (%) of WBS > 4.6 kg.