• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.357-364
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• 2018

Fly ash is a material used as a concrete admixture. When fly ash is used for concrete manufacturing, it is expected to improve the performance such as reduction of cement usage and increase of chemical resistance. However, fly ash have some problems such as unburned carbon content and amorphous film on the surface of fly ash particles. When concrete is manufactured using fly ash containing a large amount of unburned carbon, there is a problem that the slump is lowered due to adsorption of AE agent. In addition, the amorphous film on the surface of the particles prevents the reactive substances from leaching out of the fly ash. Therefore, a method of surface treatment of fly ash using plasma has been studied to remove such unburned carbon and amorphous films. However, plasma has the problem that $O_3$ is generated when $O_2$ is used as an active gas. $O_3$ is a harmful substance and adversely affects the health of the experimenter. In this study, the surface of fly ash was treatment by arc discharge. Experimental results show that the unburned carbon is removed when the surface of fly ash is treatment by arc discharge and the amorphous film was broken and the reactivity was improved. Therefore, it is considered that arc discharge can treatment the surface of fly ash and improve the quality of fly ash.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.152-158
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• 2019

Measure the type and content of VOCs for A-company epoxy coating and B-company floor coating(Type A, B), which are used as flooring materials for parking lots. Than the VOCs used gas detectors to measure gas emissions, assuming the worst environment to reduce errors in external environments in the formaldehyde, toluene and xylene harmful to workers and tenants. As a result, A-company epoxy coating has the largest amount of VOCs, and compared to A-company epoxy coating, B-company floor coating of A type represented about 79% less and B type about 96% less. In addition, A-company epoxy coating was also the highest in gas emission measurement for formaldehyde, toluene and xylene using gas detector after 1 hour and 8 hours in closed environment conditions. B-company floor coating A type was less than A-company epoxy coating, which was about 42.3% less measured. And type B satisfied all TWA even in closed environment conditions.

• The Journal of Society for e-Business Studies
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• v.24 no.2
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• pp.71-89
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• 2019

In order to come up with satisfying product and improvement, firms use traditional marketing research methods to obtain consumers' opinions and further try to reflect them. Recently, gathering data from consumer communication platforms like internet and SNS has become popular methods. Meanwhile, with the development of information technology, mobile companies are launching new digital products for children to protect them from harmful content and provide them with necessary functions and information. Among these digital products, Kids Phone, which is a wearable device with safe functions that enable parents to learn childern's location. Kids phone is relatively cheaper and simpler than smartphone but it is noted that there are several problems such as some useless functions and frequent breakdowns. This study analyzes the reviews of Kids phones from domestic mobile companies, identifies the characteristics, strengths and weaknesses of the products, proposes improvement methods strategies for devices and services through SNS consumer analysis. In order to do that customer review data from online shopping malls was gathered and was further analyzed through text mining methods such as TF/IDF, Sentiment Analysis, and network analysis. Customer review data was gathered through crawling Online shopping Mall and Naver Blog/$Caf\acute{e}$. Data analysis and visualization was done using 'R', 'Textom', and 'Python'. Such analysis allowed us to figure out main issues and recent trends regarding kids phones and to suggest possible service improvement strategies based on sentiment analysis.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.165-173
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• 2019

Hydrazine[$N_2H_4$] is a typical propellant for a rocket fuel in the field of aerospace. Since it is very toxic and harmful to the environment, various environmentally-friendly propellants have been developed. In this study, relatively a safe propellant, hydroxylammonium nitrate[$NH_3OHNO_3$], was prepared via a neutralization reaction of hydroxylamine[$NH_2OH$] and nitric acid[$HNO_3$]. FT-IR was used to analyze the chemical composition, chemical structure and functional groups of HAN. Thermogravimetric analysis showed the decomposition temperature of HAN. Ion chromatography was also used to evaluate the content of nitrate ions. It was proved that the peaks of FT-IR at $3161cm^{-1}$ and $1324cm^{-1}$ indicates the functionalities of N-H and N-O present in HAN. The decomposition temperature of HAN synthesized at pH 5 to 7 was $120-140^{\circ}C$, and pH 8 resulted in higher decomposition temperature than $140^{\circ}C$. Meanwhile, the sample obtained from pH 6-7 showed the concentration of nitric acid ion with 70%.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.455-462
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• 2020

Leuconostoc mesenteroides CJNU 0705 was isolated from a breast milk sample and identified by 16S rRNA gene sequencing and confirmed by its ability to produce dextran from tryptic soy agar plates supplemented with 2% sucrose. This strain can absorb various heavy metals including lead (Pb) and cadmium (Cd) which are both found in fine dust and have been shown to be harmful to human skin. In addition, Leu. mesenteroides CJNU 0705 has demonstrated antimicrobial activity against Propionibacterium acnes, the primary causative agent of acne. Given these traits it was natural to evaluate the use of this strain in the fermentation of several natural extracts from green tea, carrot, annual wormwood, parsley, broccoli, and corn silk, which are known to improve skin health, to see if it could increase their dextran content when supplemented with no sucrose, 2% sucrose, or 2% sucrose and 3% yeast extract. The extracts supplemented with both yeast and sucrose were found to produce the most dextran, which was confirmed by the scanning electron microscope (SEM) images. These results suggest that Leu. mesenteroides CJNU 0705 and its fermented natural extracts could be used as functional materials for improving human skin health.

• Informatization Policy
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• v.28 no.2
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• pp.57-80
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• 2021

This study aimed to identify the causes of adult cyberbullying, an issue which arouses little academic interest despite its seriousness and its harmful consequences, in order to provide basic data for the formulation of reasonable measures for preventing and reducing adult cyberbullying. To that end, the author of the study analyzed the results of the government-led Cyber Violence Survey conducted in 2019. First, the online survey panel owned by the research company selected a sample of 1,500 adult men and women in their 20s to 50s in proportion to reflect the composition of the local population. The survey was conducted online, with male subjects and female subjects accounting for 51.5% and 48.7% of the respondents, respectively. The result of the analysis shows that the respondents' attitude towards cyberbullying was fully mediaed according to such factors as gender, age, family relations, relationship with colleagues, Internet usage time, and contact with illegal content. In addition, partial mediation was observed with regard to online delinquency colleague numbers and cyberbullying victimization. As a result, the respondents' attitude towards cyberbullying was found to be the most important factor affecting adult cyberbullying. Based on these results, this study suggests that the formation of a non-conservative attitude towards cyberbullying should be considered to be more important than any other factors when preparing programs aimed at preventing cyberbullying.

• Food Science and Industry
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• v.55 no.2
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• pp.128-139
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• 2022

Although edible insects are attracting attention as future alternative food because of their nutritional, eco-friendly, and economic advantages and functionality, consumption is low, so measures to promote consumption are needed. The problems in edible insect consumption were identified as the aversion to the edible insects, lack of publicity for edible insects newly registered in the Food Code, and difficulties in continuously supplying high-quality edible insects and selling products. To solve these problems, it is necessary to establish effective public relations plans for new edible insects and develop processing methods for improving their taste and flavor, education content about edible insects, and products interesting to the target age. In addition, it is necessary to establish a one-stop cluster that can perform quality control of harmful substances and nutrients, purchase raw materials, sell products, educate, and publicize.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.3
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• pp.513-525
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• 2022

The immutability of blockchain is core elements of security of blockchain and guarantee data integrity. However, the characteristic that the data recoreded once in the blockchain cannot be modified has place for abuse by a specific user. In fact improper contents that is inappropriate to be recorded on the blockchain, such as harmful data and user personal data, is exposed on Bitcoin. As a way to manage improper content existing in the blockchain, there is a redactable blockchain using chameleon hash proposed for the first time by Ateniese. The redactable blockchain meet the right to be forgotten of GDPR by allowing data modification and deletion. Recently, Research on personal data management is being conducted in a redactable blockchain. Research by Jia et al. proposed a model that enables users to manage their personal data in the redactable blockchain. However, semi trusted regulators, which are blockchain participation nodes, have powerful authority in the blockchain, such as modification rights and deprivation of transaction rights for all blocks, which may cause side effects. In this paper, to weaken the authority of regulators in Y. Jia et al., we propose a method of authority subject altering and authority sharing, and propose a redactable blockchain-based authority change and access control system model based on applicable scenarios.

• Korean Journal of Poultry Science
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• v.38 no.1
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• pp.71-80
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• 2011

This study was conducted to investigate the effects of dietary supplementation of CS682, a fermentation product of Actinomycetae Nocardia sp. CS682, and DCS682$^{(R)}$, a commercial product, on the performance, blood parameters, small intestinal microflora, and immunoglobulin contents in broilers. In Exp. 1, a total of 240 ROSS$^{(R)}$ broiler chickens of 1d old were assigned to six dietary treatments: Control, Antibiotics (6 ppm avilamycin), CS682-0.25 (CS682 0.25%), CS682-0.50, CS682-0.75 and CS682-1.00. There were significant (p<0.05) differences among treatments in feed conversion. The CS682-0.25 treatment was significantly (p<0.05) lower than Antibiotics and other CS682 treatments in 0~2 wk feed conversion. The CS682 treatments influenced MCV (mean corpuscular volume) in blood. The cfu of Escherichia coli in small intestinal content was lowest in Antibiotics treatment followed by CS682 treatments and Control. In Exp. 2, a total of 1,000 ROSS$^{(R)}$ broiler chickens of 1 d old were assigned to five dietary treatments: Control, Antibiotics (6 ppm avilamycin), DCS682-0.05 (DCS682$^{(R)}$ 0.05%), DCS682-0.10 and DCS682-0.20. There were significant differences (p<0.05) among treatments in mortality. The DCS682-0.20 treatment was lower than DCS682-0.10 in 0~3 wk and lower than Control in 0~5 wk mortality. Antibiotics treatment was lowest in all microbial population in small intestinal content. The cfu of E. coli and Salmonella typhimurium of DCS682 treatments were higher than Antibiotics treatment but lower than the Control. The results of present broiler experiments indicated that supplementation of 0.20~0.25% CS682 and DCS682, improve feed conversion, mortality and control harmful intestinal microbes.

• Food Science and Preservation
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• v.24 no.8
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• pp.1168-1179
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• 2017

In this study, we tried to screen the Bacillus strain having safety probability by isolation of strains from traditional fermented food, measurement of probiotic properties, and the fermentative characteristics of Cheonggukjang. We isolated 400 Bacillus-like isolates from traditional fermented foods. Selected strains examined on the prevalent characteristic such as extracellular enzyme and antibacterial activities, and their safety probability was confirmed by biogenic amine productivity, hemolytic, and harmful substances and enzyme productivity. We selected the 5 strains by analysis of biogenic amine, antibacterial and B. cereus toxic associated gene. Five selected strains were examined on cell surface hydrophobicity, and bile and acid tolerance, and we selected the SRCM100730 as the final strain. SRCM100730 was confirmed B. amyloliquefaciens by 16S rRNA sequencing, and named the B. amyloloquefaciens SRCM100730 (KCCM11966P). Finally, we manufactured Cheonggukjang using SRCM100730 for confirmation of fermentation properties. Manufactured Cheonggukjang did not contain B. cereus, and showed that ${\gamma}$-PGA and extracellular enzyme activities were superior to commercial Chunggukjang. Amino nitrogen content was 544.02 mg% and 26 free amino acid were detected, and the bitterness-related amino acid content was lower than commercial Cheonggukjang. Especially, the amount of GABA was 3 fold higher than commercial Cheonggukjang. These results suggest that SRCM100730 have high availability in commercial probiotics market and fermented food industry.