• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1982-1992
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• 2019

The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 10⁸ and 1.25 ± 0.12 × 10⁸ CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 10⁹ CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 10⁶ CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.839-845
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• 2007

Temperature dependence of kinetic constants in the anaerobic acidogenesis was investigated using anaerobic chemostat-type reactor. Glucose was used as a substrate in this experiment. Temperature ranging from 15 to $30^{\circ}C$ were studied. The saturation constant$(k_s\upsilon)$ and growth yield(Y) decreased with increasing temperature, while the maximum specific substrate utilization rate$(\upsilon_{max})$ increased. A temperature correction factor$(Q_{10})$ values of the substrate utilization rate and bacteria growth rate were the range from 1.3 to 2.2 and 1.5 to 2.2, respectively. The growth yield(Y) for the acidogenesis process was less sensitive to temperature changes than the maximum specific substrate utilization rate$(\upsilon_{max})$. The simulation model of the relationship between the substrate and sludge retention time(SRT) at the temperature range of 20 to $30^{\circ}C$ is obtained as the following ; $1/SRT={(6.53){\cdot}(1.038)^{T-20}{\cdot}(S/X)}/{(1.38){\cdot}(0.983)^{T-20}+(S/X)}$.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.246-251
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• 2005

The aim of this study was to evaluate an efficacy about activation on macrophage, using model that measured cell viability, nitric oxide (NO), iNOS (inducible nitric oxide synthase) expression and tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) on Raw 264.7 cells following treatment of Germanium-fortified Yeast in 0, 5, 10, 25, 50, 100, $200\;{\mu}g/ml$ and the same concentration of dried yeast without germanium. Cell viability (%) and NO produced in activated-macrophage were dose-dependant, a significant increase of the cell viability (132.5%) and NO in $10\;{\mu}g/ml$ (p < 0.05). Increase in iNOS level was in $10\;{\mu}g/ml$. $TNF-{\alpha}$ was produced dose-dependant, e.g. in activated-macrophage with a significant increase of the $TNF-{\alpha}$ in 5 and $10\;{\mu}g/ml$ (p < 0.05). Therefore, Germanium-fortified Yeast had an efficacy of NO mediated iNOS and $TNF-{\alpha}$ production by activated macrophage. This result showed that Germanium-fortified Yeast induced activation of cellular immunity, returned to normalcy on injured immune system and procured anticancer system by activation of macrophage, which was important in immune and anticancer function.

• The Journal of the Korea Contents Association
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• v.18 no.2
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• pp.509-519
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• 2018

This is a correlational study to investigate the degree of expectation regarding aging, depression and health promotion lifestyle and to identify the factors influencing health promotion lifestyle among health checkup examinee. The subjects of the study were 143 health checkup examinee who visited the M medical center located in G Metropolitan city. Data were collected from July 5 to 21, 2016 using the structured questionnaire of self-report form. Data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation, and hierarchical regression. As a result, health promoting lifestyle were correlated with expectation regarding aging positively, and with depression negatively. The factors influencing the health promotion lifestyle were education level, perceived health status, time to move to health care facilities, expectation regarding aging, and depression. With controlled general characteristics, the level of health promotion lifestyle was better explained by the addition of the independent variables of expectation regarding aging, and depression, and the explanatory power of the final model was calculated as 27.0%. Therefore, in order to improve health-promoting lifestyle, it is necessary to consider cognitive factors (knowledge, expectation regarding aging) and psychological factor (depression) besides physical approach.

• Journal of Food Hygiene and Safety
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• v.19 no.3
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• pp.126-131
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• 2004

This study was conducted to investigate of inhibition activity of yuza (Citrus junos) extracts and juice on nitrite scavenging and N-nitrosodimethylamine (NDMA) formation in model system. Yuza juice was separated into organic acid, ascorbate and phenolic portion using sep-pak $C_{18}$ cartridge, respectively. Nitrite scavenging activity and inhibition of NDMA formation from yuza extract has shown higher inhibition with pH of reaction condition lower and amount of added sample more. And peel extract of yuza was higher than those of flesh extract. Nitrite scavenging activity was excellent juice portion rather that 3 portions. Of the 3 portions, it activity was the highest in the organic acid portion, and decreased in the following order; phenolic acid, ascorbate portion. Therefore, organic acid of yuza was suggested to expect effective ihhibitor of NDMA formation.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.141-147
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• 2018

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, $180^{\circ}$ rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.444-455
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• 2018

This empirical study examined the relationships among emotional labor, social support, and organizational commitment of franchise food service industry employees, and analyzed the mediating effects of social support from the fellow and director on the relationship between emotional labor and organizational commitment. A total of 268 employees in the franchise food service industry, such as fast food, chicken, and coffee in Seoul, were analyzed by frequency analysis, reliability analysis, correlation analysis, confirmatory factor analysis, and structural equation model analysis using the SPSS Program. The results of verifying the research hypotheses could be summarized as follows. First, the surface emotional labor of franchise food service industry employees had negative effects on the organizational commitment. Deep emotional labor had significant positive effects on the organizational commitment, and fellow and director support had significant positive effects on the organizational commitment. Second, the social support from the fellow and director had partially mediating effects on the relationship between emotional labor and organizational commitment. This suggests that emotional labor and social support play essential roles in enhancing the organizational commitment of franchise food service industry employees.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.490-497
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• 2018

This study is to identify factors influencing therapeutic diversification strategy for Korean pharmaceutical companies. So, it purposes to find deciding factors for companies to adopt strategy for diversification or specialization. In this paper, we set six factors that are expected to influence diversification. The factors are asset scale, sales, profitability, and growth potential. Also, we included number of employees and SG&A cost ratio as factors that reflect business characteristics. We analyzed the impacts of each factor on diversification and found a relationship amongst each other. In this paper, regression analysis is applied with forward selection method, considering that it takes 5 years for companies to decide on diversification strategy. As a result, asset scale, the number of employees and profitability have significantly influenced decisions of diversification at t-1 time, and growth potential was significantly influenced at t-2 time. Korean pharmaceutical companies generally tend to go with specialization model if they have larger asset scale, higher profitability and growth potential. However, they have tendency to decide on diversification strategy, if they have large number of employees. Overall, the result of this study is expected to provide useful information for Korean pharmaceutical companies to set the suitable strategy for their situation to become a competitive company in global pharmaceutical market.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.667-674
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• 2020

The adsorption of reactive orange 16 (RO 16) dye by activated carbon was investigated using the amount of adsorbent, pH, initial concentration, contact time and temperature as adsorption variables. The investigated process parameters were separation coefficient, rate constant, rate controlling step, activation energy, enthalpy, entropy, and free energy. The adsorption of RO 16 was the highest at pH 3 due to the electrostatic attraction between the cations (H⁺) on the surface of the activated carbon and the sulfonate ions and hydroxy ions possessed by RO 16. Isotherm data were fitted into Langmuir, Freundlich and Temkin isotherm models by applying the evaluated separation factor of Langmuir (RL=0.459~0.491) and Freundlich (1/n=0.398~0.441). Therefore, the adsorption operation of RO 16 by activated carbon was confirmed as an appropriate removal method. Temkin's adsorption energy indicated that this adsorption process was physical adsorption. The adsorption kinetics studies showed that the adsorption of RO 16 follows the pseudo-second-order kinetic model and that the rate controlling step in the adsorption process was the intraparticle diffusion step. The positive enthalpy change indicated an endothermic process. The negative Gibbs free energy change decreased in the order of -3.16 <-11.60 <-14.01 kJ/mol as the temperature increased. Therefore, it was shown that the spontaneity of the adsorption process of RO 16 increases with increasing temperature.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2
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• pp.133-141
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• 2020

A geological repository comprises a natural barrier and an engineered barrier system. Its design components consist of canisters, buffers, backfill, and near-field rock. Among the engineered barrier system components, bentonite buffers minimize the groundwater flow from near-field rock and prevent the release of nuclide. Investigation of the hydraulic conductivity of the buffer to groundwater flow is an important factor in the performance evaluation of the stability and integrity of the engineered barrier of the repository. In this study, saturated hydraulic conductivity tests were performed using Gyeongju bentonite at various dry densities and temperatures, and a hydraulic conductivity prediction model was developed through multiple regression analysis using the 120 result sets of hydraulic conductivity. The test results showed that the hydraulic conductivity tends to decrease as the dry density increases. In addition, the hydraulic conductivity increased with increasing temperature. The multiple regression analysis results showed that the coefficient of determination (R²) of the hydraulic conductivity prediction equation was as high as 0.93. The hydraulic conductivity prediction equation presented in this study could be used for the design of engineered barrier systems.