• Tunnel and Underground Space
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• v.31 no.3
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• pp.167-183
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• 2021

It is essential to understand the complex thermo-hydro-mechanical-chemical (THMC) coupled behavior in the engineered barrier system and natural barrier system to secure the high-level radioactive waste repository's long-term safety. The heat from the high-level radioactive waste induces thermal pressurization and vaporization of groundwater in the repository system. Groundwater inflow affects the saturation variation in the engineered barrier system, and the saturation change influences the heat transfer and multi-phase flow characteristics in the buffer. Due to the complexity of the coupled behavior, a numerical simulation is a valuable tool to predict and evaluate the THMC interaction effect on the disposal system and safety assessment. To enhance the knowledge of THMC coupled interaction and validate modeling techniques in geological systems. DECOVALEX, an international cooperation project, was initiated in 1992, and KAERI has participated in the projects since 2008 in Korea. In this study, we introduced the main contents of all tasks in the DECOVALEX-2023, the current DECOVALEX phase, to the rock mechanics and geotechnical researchers in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.398-407
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• 2021

Firefighters (who are responsible for people's safety) have one of the jobs that are expected to have problems due to aging in the workforce. An increase in the average age of firefighters can lead to serious social problems. The aim of this study is to survey firefighters in Jeollanam-do about their awareness of aging in firefighters, and to propose a plan to prepare them for aging through investigation and analysis of work problems that may occur due to an aging workforce. The survey shows that the higher the age group, the higher the awareness of aging firefighters, and the higher the total work experience and internal/external work experience, the higher the awareness of aging. As a plan to solve various problems that may arise from aging in firefighters, regular operation of physical fitness promotion programs, field work, job rotation, and managerial measures (such as a change of position to an administrative department) are prepared, and drone or robot technology is used. These solutions include the introduction of applied high-tech technologies to firefighting activities, establishment of retirement management policies, and preparation of plans to revitalize the connection to private employment. In order to maximize the applicability of the field, government institutional plans and preparations are essential.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.607-617
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• 2020

Human bio-monitoring (HBM) data is a very important resource for tracking total exposure and concentrations of a parent chemical or its metabolites in human biomarkers. However, until now, it was difficult to execute the integration of different types of HBM data due to incompatibility problems caused by gaps in study design, chemical description and coding system between different sources in Korea. In this study, we presented a standardized code system and HBM knowledge model (KM) based on relational database modeling methodology. For this purpose, we used 11 raw datasets collected from the Ministry of Food and Drug Safety (MFDS) between 2006 and 2018. We then constructed the HBM database (DB) using a total of 205,491 concentration-related data points for 18,870 participants and 86 chemicals. In addition, we developed a summary report-type statistical analysis program to verify the inputted HBM datasets. This study will contribute to promoting the sustainable creation and versatile utilization of big-data for HBM results at the MFDS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.153-160
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• 2021

Nitrous oxide is a global warming substance and is known as the main cause of the destruction of the ozone layer because its global warming effect is 310 times stronger than carbon dioxide, and it takes 120 years to decompose. Therefore, in this study, we investigated the characteristics of NOx emission from N2O reduction by thermal decomposition of N2O. Bunsen premixed flames were adopted as a heat source to form a high-temperature flow field, and the experimental variables were nozzle exit velocity, co-axial velocity, and N2O dilution rate. NO production rates increased with increasing N2O dilution rates, regardless of nozzle exit velocities and co-axial flow rates. For N2O, large quantities were emitted from a stable premixed flame with suppressed combustion instability (Kelvin Helmholtz instability) because the thermal decomposition time is not sufficient with the relatively short residence time of N2O near the flame surface. Thus, to improve the reduction efficiency of N2O, it is considered effective to increase the residence time of N2O by selecting the nozzle exit velocities, where K-H instability is generated and formed a flow structure of toroidal vortex near the flame surface.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.107-113
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• 2022

A number of studies have been conducted to confirm the preventive effect of xylitol on dental caries as a whole or partial alternative to dietary sugars. This study reviewed the oral health effects of xylitol on the prevention mechanism of dental caries, the prevention of dental caries, the inhibition of mother-to-child transmission, and the oral health effects in the elderly based on existing studies on the oral health of xylitol. Carbohydrates and dietary sugars in food are fermented by acid-producing microorganisms in the mouth and produce dental plaque and acid, which cause dental caries. However, most dental decay-causing bacteria cannot produce acids by metabolizing xylitol. Xylitol, stored in cells as a non-metabolizable metabolite by Streptococcus mutans (S. mutans), affects bacterial glucose metabolism and inhibits bacterial growth. Xylitol consumption also reduces the amount of plaque and the population of S. mutans in both plaque and saliva. In addition, xylitol acts in the remineralization process. Xylitol has been confirmed to effectively prevent dental caries, inhibit mother-to-child transmission of MS, prevent dental caries, and increase salivary flow in the elderly. In conclusion, xylitol is an adequate sugar substitute for dental health, from infants to the elderly. For future studies, the researchers recommend reviewing the effects of xylitol on the oral and intestinal microbial environment and the side effects of excessive intake.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.112-118
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• 2022

In this study, the diffusion characteristics were evaluated using the concrete mix design of nuclear safety-related structures. Among the concrete structures related to nuclear power safety, we selected the composition of intake and drainage structures that are immersed in seawater or located on the tidal platform and evaluated the chloride ion permeation resistance by compressive strength and electrical conductivity and the diffusion characteristics by immersion in salt water. analyzed. Compressive strength was measured on the 1st, 7th, 14th, 28th, 56th, and 91st days until the 91st day, which is the design standard strength of the nuclear power plant concrete structure, and chloride ion permeation resistance was evaluated on the 28th and 91st. After immersing the 28-day concrete specimens in salt water for 28 days, the diffusion coefficient was derived by collecting samples at different depths and analyzing the amount of chloride. As a result, it was found that after 28 days, the long-term strength enhancement effect of the nuclear power plant concrete mix with 20% fly ash replacement was higher than that of concrete using 100% ordinary Portland cement. It was also found that the nuclear power plant concrete mix has higher chloride ion permeation resistance, lower diffusion coefficient, and higher resistance to salt damage than the concrete mix using 100% ordinary Portland cement.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.176-183
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• 2023

The extraction and filtration of red ginseng with a mixed solvent of water and alcohol-a common processing method-and the production of a concentrate through heat treatment, such as steaming, leads to its hydrolysis or polymerization. Approximately 200 ginsenosides have consequently been detected in small amounts, in addition to the identification of the functions of approximately 30 major ginsenosides. This complicates the identification of the functionality of red ginseng and its efficacy, and has negative effects as a functional food, as the astringent taste becomes stronger with an increase in the number of extractions. The red ginseng concentrate was, therefore, extracted at a low temperature (less than 40 ℃) and processed to eliminate these negative aspects, with a specific focus on the characteristics of the functional components of ginsenosides.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.620-627
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• 2023

Ship noise is one of the important factors for the living and health of seafarers, and ef orts to reduce ship noise are actively underway. There are two methods of noise reduction: passive noise Control (PNC) and active noise control (ANC). Unlike cars and airplanes, ANC is not widely used for noise reduction on ships. This study aimed to reduce the noise generated in the engine room by using soundproof panels and high-frequency vibration generators, as well as active noise control (ANC). For this purpose, an experimental model was made using an acrylic box, and the noise reduction effect was measured under four conditions. The experimental results are as follows: First, the soundproof panel had a noise reduction effect in all ranges from 55 dB to 85 dB. In the case of using a high-frequency vibration generator, there was no ef ect in the low noise range such as 55 dB(A), but there was a noise reduction effect in the high noise range such as 70.8 dB(A) and 85 dB(A).Second, when the soundproof panel and the high-frequency vibration generator were used simultaneously, the noise reduction ef ect was up to -2.2 dB(A). The results of this experiment were obtained from an experimental model made of acrylic, and they may be different from actual ships made of steel plate. In future studies, we plan to experiment using iron plate (considering the material, thickness, and structure) used in actual ships. We hope that this study will help to improve the living environment and health of seafarers on ships.

• Information Systems Review
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• v.22 no.4
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• pp.185-203
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• 2020

With the advent of 4th industrial revolution, the manufacturing industry is converging with ICT and changing into the era of smart manufacturing. In the smart factory, all machines and facilities are connected based on ICT, and thus security should be further strengthened as it is exposed to complex security threats that were not previously recognized. To reduce the risk of security incidents and successfully implement smart factories, it is necessary to identify key security factors to be applied, taking into account the characteristics of the industrial environment of smart factories utilizing ICT. In this study, we propose a 'hierarchical classification model of security factors in smart factory' that includes terminal, network, platform/service categories and analyze the importance of security factors to be applied when developing smart factories. We conducted an assessment of importance of security factors to the groups of smart factories and security experts. In this study, the relative importance of security factors of smart factory was derived by using AHP technique, and the priority among the security factors is presented. Based on the results of this research, it contributes to building the smart factory more securely and establishing information security required in the era of smart manufacturing.

• Journal of Korean Academy of Nursing
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• v.23 no.4
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• pp.585-601
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• 1993

Data on 63 patients who had had motorcycle accidents and who were admitted to four general hospitals in the Chung Chung Nam Do area from July / 1993 to August 1993 were analyzed. The tool used for this study was a structured questionnaire which consisted of ten items on self- esteem, 18 items on health locus of control and 37 items profiling health prometion lifestyle. Injury severity scores were calculated bated based on data from the patients’ medical records. The collected data were analyzed using the SPSS, yielding descriptive statistics, t-test, ANOVA, Pearson’s Product Moment Correlation. The findings of this study are as follows. 1) Of the 63 injured motorcyclists, 35(55.6%) were helmeted and 28(44.4%) were nonhelmeted, and the nonhelmeted motorcyclists were predominantly young and male. The demographic variables for the helmeted and nonhelmeted groups were heterogeneous for age and occupation. 2) The results of the comparison between the two groups showed a statistically significant difference in the injury severity score(t=-4.70, p=0.000). The helmeted group had lower scores on injury severity score (9.00±3.93) than the nonhelmeted group(14.32土5.05). More than 60% of the nonhelmeted motorcyclists had brain injuries compared to only a third of the helmeted cyclists. 3) There .was a statistically significant difference between the two groups on self esteem(t=4.5, 000). The helmeted group had a higher mean score (31.27±2.72) than the nonhelmeted group(27.46±3.80). 4) The means for Internal health locus of control (IHLC), Powerful others health locus of control (PHLC), and Chance health locus of control (CHLC) in the two groups were similar to instrument norms reported in other literature. The mean scores on the IHLC in the two groups were higher than scores on the PHLC or the CHLC. However, there was a significant difference between the mean scores for the two groups on the PHLC (t=2.85, P=0.006). 5) The mean score for the helmeted group on the health promotion lifestyle profile was higher than the mean score for the nonhelmeted group(107.30±11.10, 96.57土 15.54 respectively), and there was a significant difference between the mean scores (t=3.64, p=0.001) . The highest score for helmeted group on the health promotion lifestyle profile was in the health care domain. However, for the nonhelmeted group the highest score was in the exercise domain and the lowest score was in the health care domain. 6) With regard to the relationship between health promotion lifestyle, health locus of control and self esteem in the two groups, the correlation coefficient between health promotion lifestyle and internal health locus of control for the helmeted group was 50(p〈0.01). For the nonhelmeted group, there was no correlation between health promotion lifestyle and internal health locus of control. However, there were significant correlation between health pro-motion lifestyle and external locus of control(r=0. 46, p〈0.01), and self esteem(r=0.495, p〈0.01). 7) Among the demographic variables, age and education had an impact on individual’s self-esteem The modifying factors of age made a contribution to explaining health - promoting lifestyle. In the present study, more than 40% rf the motorcyclists were riding without a helmet. The incidence of brain injury for patients riding without a helmet was nearly twice as high in the nonhelmeted rider as compared to the helmeted rider. The nonhelmeted motorcyclists in this study had lower self-esteem, obtained a higher score on the IHLC, and were not strongly engaged in performing health promotion activities as compared to the helmeted riders. However, some of the nonhelmeted riders who had a strong belief in PHLC were positively associated with engaging in health promotion activities. Based on the results obtained from this study, strategies to promote helmet usage for motorcyclists have to be developed.