• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.1-10
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• 2021

The purpose of the study is to contribute to the positive development of blockchain technology by providing data to examine security vulnerabilities and threats to blockchain-based services and review countermeasures. The findings of this study are as follows. Threats to the security of blockchain-based services can be classified into application security threats, smart contract security threats, and network (P2P) security threats. First, application security threats include wallet theft (e-wallet stealing), double spending (double payment attack), and cryptojacking (mining malware infection). Second, smart contract security threats are divided into reentrancy attacks, replay attacks, and balance increasing attacks. Third, network (P2P) security threats are divided into the 51% control attack, Sybil attack, balance attack, eclipse attack (spread false information attack), selfish mining (selfish mining monopoly), block withholding attack, DDoS attack (distributed service denial attack) and DNS/BGP hijacks. Through this study, it is possible to discuss the future plans of the blockchain technology-based ecosystem through understanding the functional characteristics of transparency or some privacy that can be obtained within the blockchain. It also supports effective coping with various security threats.

• Journal of Environmental Science International
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• v.17 no.4
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• pp.439-449
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• 2008

Algicidal bacterium was isolated from sea water during the declining period of Cochlodinium polykrikoides blooms and this bacterium had a significant algicidal activity against C. polykrikoides. In this study, algicidal bacterium was identified on the basis of biochemical and chemotaxonomic characteristics, and analysis of 16S rDNA sequences. The algicidal bacterium showed 98.6% homology with Micrococcus luteus ATCC $381^T$. Therefore, this bacterium was designated Micrococcus luteus SY-13. The optimal culture conditions of the algicidal bacterium was $25^{\circ}C$, initial pH 8.0, and 3.0% NaCl concentration. M. luteus SY-13 is assumed to produce secondary metabolites which have algicidal activity. When 10% culture filtrate of this strain was applied to C. polykrikoides ($1.0\;{\times}\;10^4\;cells/ml$) cultures, over 98% of C, polykrikoides cells were destroyed within 6 hours. The culture filtrate of M. luteus SY-13 exhibited similar algicidal activity after heat-treatment at $121^{\circ}C$ for 15 min. While algicidal activity remained in filtrates with pH adjusted to 8.0, loss of algicidal activity occurred when the pHs of filtrates were adjusted to over 9.0 or heat-treated at $121{\times}180^{\circ}C$ for 1 hour. M. luteus SY-13 showed significant algicidal activities against C. polykrikoides (98.9%) and a wide algicidal range against various harmful algal bloom (HAB) species. However, there was no algicidal effect on diatom and marine livefood organisms except Isocrysis galbana. These results suggest that M. luteus SY-13 could be a candidate for use in the control of HABs.

• KSBB Journal
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• v.14 no.4
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• pp.434-439
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• 1999

A wild yeast S-13 which has excellent killer toxin activity to gas-producing yeast of traditional Doenjang and Kochujang was selected among forty seven strains of Meju yeasts and identified as Hansenular capsulata S-13 by investigation of the morphological, cultural and physiological properties. The optimal conditions for the production of killer toxin were investigated. H. capsulata s-13 showed the higest killer toxin activities when it was cultured up to the late-log phase of 36 hr in YEPD medium (pH4.5) at $25^{\circ}C$ H. capsultara S-13 showed killer toxin activities to seven strains of industrial yeasts such as S. cerevisiae, C. veratilis and P. membranaefacieus.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.667-674
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• 2004

The objective of this study was to investigate the effects of pH and temperature on the formation of bromate, which is ozonation by-products, during ozonation. In this experiment, the operating parameters including pH 3 ～ 10 and temperature 15 ～ $30^{\circ}C$ were studied. Through the study for the bromate formation, reaction rate constant, and ozonation effect index on pH and temperature, the results obtained are as follows. At the same initial pH condition, the increase of pH shown similar trends even if the reaction variables such as temperature and reaction time of ozonation were exchanged. As pH and temperature were increasing, the bromate concentration was increased but bromine(HOBr+OBr) was decreased with increasing pH from 3 to 10. The activation energy(J/mol) for bromate formation decreased with increasing pH. The rate constants of bromate formation for the reaction of ozone and bromide, and ozone dosage coefficient$(K_{0})$ increased with temperature and pH. Ozonation effect index(OI) decreased with increasing temperature and pH.

• The Korean Journal of Food And Nutrition
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• v.33 no.3
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• pp.266-278
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• 2020

This study was conducted with 375 workers in Changwon to examine the effects of working patterns on dietary habits and health. A self-administered questionnaire was conducted July 22 October 30, 2019. According to the results of the dietary habits and health related factors analysis, non-shift administrative workers showed significantly higher rates of green tea intake (p<0.05), and shift production workers showed significantly higher smoking rates (p<0.001) and waist circumferences (p<0.01). According to the results of the Pearson's correlation coefficient analysis, work hours showed negative correlations with job satisfaction (r=0.22, p<0.01) and positive correlations with perceived stress level (r=0.14, p<0.01). Temporary workers showed negative correlations with feel job satisfaction(r=0.14, p<0.01), perceived stress level (r=0.12, p<0.05), and concern about health (r=0.13, p<0.05). Diabetes showed positive correlations with hypertension (r=0.20, p<0.01), low HDL cholesterolemia (r=0.22, p<0.01), abdominal obesity (r=0.13, p<0.05), and hypertriglyceridemia(r=0.22, p<0.01). Based on these results, this researcher proposes that continuous attention and support of industries and communities are necessary for nutritional education and counseling relative to improving workers' dietary lives as well as disease prevention and control.

• Macromolecular Research
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• v.13 no.6
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• pp.467-476
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• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.

• The Journal of Korean Academic Society of Nursing Education
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• v.27 no.4
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• pp.392-401
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• 2021

Purpose: This study was conducted to identify the relationship of health status, aging anxiety, social networking, generativity, and happiness and to investigate the main factors influencing happiness of late middle-aged adults. Methods: The study collected data from a total of 153 middle-aged men and women aged 50 to 64 years old from a consumer panel of Macromill-Embrain, the biggest online survey provider in Korea. The data were analyzed using descriptive statistics, Pearson's correlation coefficient and a stepwise multiple regression using the SPSS 22.0 program. Results: The subjects' happiness mean score was 16.17±9.29. Statistically significant differences in happiness were found according to education (F=4.38, p=.014), economic status (t=5.13, p<.001), and religion (t=2.18, p=.031). Happiness was correlated significantly with health status (r=.41, p<.001), aging anxiety (r=-.62, p<.001), family support (r=.43, p<.001), friend support (r=.36, p<.001) and generativity (r=.63, p<.001). The factors influencing happiness of late middle-aged adults were generativity (𝛽=.37, p<.001), aging anxiety (𝛽=-.35, p<.001), family support (𝛽=.20, p<.001), and economic status (𝛽=.13, p=.033). The explanatory power of the model was 58.0%. Conclusion: This study will be used as basic data when developing a nursing intervention program for successful aging by identifying factors that affect the happiness of late middle-aged adults.

• Journal of Korean society of Dental Hygiene
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• v.20 no.4
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• pp.435-445
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• 2020

Objectives: This study investigated the relationship between obesity and dental caries of Korean adolescents. Methods: Data from the Korea National Health and Nutrition Examination Survey (KNHNES VI) (2013 to 2015) were used and targeted adolescents aged 13 to 18 years. For statistical analysis, the SPSS 18.0 program was used, and the significance level was set at 0.05. Results: For the general and health-related characteristics, female students (p=0.001) showed higher decayed, missing, and filled teeth (DMFT) index than male students. Furthermore, DMFT showed higher tendency, as age was higher (p<0.001). Smoking (p=0.011) and drinking experience (p=0.027) revealed higher DMFT. The dental caries experience was significantly different among students who were female (p=0.033), older (p=0.001), and overweight or underweight (p=0.022). In the BMI for the general and health-related characteristics, male students had higher obesity rate than female students (p=0.003), and obese subjects had higher dental checkup in the last year (p=0.013). In multiple linear regression analysis of obesity and DMFT, the unadjusted model showed that the obesity group's DMFT was about 0.8 higher than that of the normal group (p=0.024). However, statistical significance was not shown in the adjusted models. In the logistic regression analysis of obesity and dental caries experience, the unadjusted model 1 (1.93 times), the adjusted model 2 (1.79 times), and model 3 (1.76 times) showed significantly higher dental caries experience. Conclusions: Both obesity and dental caries are related to diet habits and lifestyles and have a negative impact on adult health. Therefore, it is necessary to create a healthy social environment around the adolescent, and proper intervention through education is required to form healthy habits.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.1
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• pp.103-110
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• 2012

Neoadjuvant chemotherapy for resectable esophageal carcinoma has been a focus of study, but no agreement has been reached on clinical randomized controlled trials and relevant systematic evaluation. The purpose of this study was to perform a meta-analysis on published randomized controlled trials (RCTs) that compared neoadjuvant chemotherapy and surgery with surgery alone for resectable esophageal carcinoma. Medline and manual searches was conducted in PubMed, ASCO (American Society of Clinical Oncology) meeting summary, Embase, the Cochrane Library (up to October 2010), Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Database, Wanfang Database. The selection contents were to identify all published and unpublished RCTs that compared neoadjuvant chemotherapy and surgery with surgery alone for resectable esophageal carcinoma. Sixteen RCTs which included 2,594 patients were selected. The risk ratio (RR) (95% confidence interval [CI]; P value), expressed as neoadjuvant chemotherapy and surgery versus surgery alone (treatment versus control), was 1.02 (0.95, 1.10; P=0.54) for 1-year survival, 1.29 (1.13, 1.47; P=0.0001) for 3-year survival, 1.31 (1.13, 1.51; P=0.0003) for 5-year survival, 1.00 (0.95, 1.04; P= 0.85) for rate of resection and 0.89 (0.64, 1.23; P=0.48) for operative mortality. The results showed that neoadjuvant chemotherapy for resectable esophageal carcinoma can raise the overall survival rate of patients with esophageal carcinoma, but it does not affect treatment-related mortality.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.257-263
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• 1998

Alcaligenes eutrophus was successfully recovered from high cell density broth by pre-treatment with Fe-based coagulants. An inorganic coagulant, Fe$_2$(SO$_4$)$_3$, and a polymerized coagulant, Ferix-3, were used. Good coagulation was observed in broad pH range of 3 to 13, the floe size was increased with increasing pH of culture broth. The optimum pH of fermentation broth for cell recovery was 10 to 13. The optimum coagulant dosages to recover cells with 95% cell recovery were increased with increasing cell concentration. Optimal coagulant dosage was lower when the polymerized coagulant was used rather than the inorganic coagulant. The coexistence of NH$_4$$\^$+/ was increased coagulant requirement, and the coagulant requirement was 0.066g Fe$_3$$\^$+//g NH$_4$$\^$+/.