• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.5-12
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• 2012

Antibiotics have been considered emerging compounds due to their continuous input and persistence in environment. Due to the limited biodegradability and widespread use of these antibiotics, an incomplete removal is attained in conventional wastewater treatment plants and relative large quantities are released into the environment. In this study, it was determined the adsorption and photocatalysis kinetics of antibiotics (Sulfamethoxazole, SMX) with various catalyst (Titanium dioxide; $TiO_2$, Hydroxyapatite; HAP) conditions under UV/$TiO_2$/HAP system. In addition, the statistical analysis of response surface methods (RSM) was used to determine the effects of operating parameters on UV/$TiO_2$/HAP system. $TiO_2$/HAP adsorbent were found to follow the pseudo second order reaction in the adsorption. In the result of applied intrapaticle diffusion model, the constants of reaction rate were $TiO_2$=$0.064min^{-1}$, HAP=$0.2866min^{-1}$ and $TiO_2$/HAP=$0.3708min^{-1}$, respectively.The result of RSM, term of regression analysis in analysis of variance (ANOVA) showed significantly p-value (p<0.05) and high coefficients for determination values($R^2$=96.2%, $R^2_{Adj}$=89.3%) that allowed satisfactory prediction of second order regression model. And the estimated optimal conditions for Y(Sulfamethoxazole removal efficiency, %) were $x_1$(initial concentration of Sulfamethoxazole)=-0.7828, $x_2$(amount of catalyst)=0.9974 and $x_3$(reation time)=0.5738 by coded parameters, respectively. According to the result of intraparticle diffusion model and photocatalysis experiments, it was shown that the $TiO_2$/HAP was more effective system than conventional AOPs(advanced oxidation processes, UV/$TiO_2$ system).

• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.198-206
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• 1996

Leaching of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ in paddy soil was studied using lysimeter cultures in a greenhouse. The radionuclides were applied to the water surfaces shortly before transplanting and five different times between transplanting and harvest. Fertilizer KCl and slaked lime were added simultaneously in the rate of 83kg and 200kg, respectively, per l0a following the first application after transplanting. Percolating water was sampled until two days before harvest. Concentrations of the radionuclides in percolating water decreased in the order of $^{85}Sr$ > $^{54}Mn$ > $^{60}Co$ > $^{137}Cs$ on the whole. Time taken to reach the maximum was the shortest for $^{137}Cs$(< one week) and the longest for $^{54}Mn$ and $^{85}Sr$. Six days' water dropping started 47 days after transplanting reduced the concentrations of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ by factors of 30-180, 3-75, 2-4 and 3-6, respectively, depending on the application time. After the significant decrease, $^{54}Mn$ concentration tended to gradually increase but $^{137}Cs$ did to the contrary Percent leaching varied 0.09-6.2% for $^{54}Mn$, 0.009-0.9% for $^{60}Co$, 1.4-14.4% for $^{85}Sr$ and 0.002-0.06% for $^{137}Cs$, with the application time. The highest leaching came from the application at 40 days after transplanting for all the radionuclides. The addition of KCl and lime increased percent leaching of the radionuclides by factors of 9, 85, 4 and 9, respectively.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.281-291
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• 1999

The objective of this study was to optimize the freezing/thawing method of in vitro produced Hanwoo blastocysts. Day 7 blastocysts after IVF were vitrified using EFS40 (40% ethylene glycol, 18% ficoll, 0.3 M sucrose and 10% FBS added m-DPBS) as a freezing solution and electron microscope (EM) grid (V-G) or straw (V-S) as an embryo container. In both method, freezing/thawing were treated by 2-step, treatment time was required in V-G method and V-S method, for 2 min / 3 min and 3.5 min / 10 min, respectively. Embryo survival was assessed as re-expanded and hatched rates at 24 h and 48 h after warming, respectively. The results obtained in these experiments were summarized as follows: when the effect of exposure in vitrification solution and chilling injury from freezing procedure on in vitro produced expanded blastocysts were examined, at 24 h after warming, embryo survival in exposure group (100.0%) was not different compared to that in control group (100.0%), although those results were significantly different with two vitrified groups (V-G: 87.8, V-S: 77.8%) (P＜0.001). However, at 48 h after warming, hatched rates of V-G group (67.8%) were significantly higher than those of V-S group (53.3%) (P＜0.05). In addition, this hatched rate in V-G group was not different with that in exposure group (73.3%). When the effects of embryo developmental stage (early, expanded and early hatching blastocysts) and embryo container (EM grid and straw) to the in vitro survival of vitrified-warmed day 7 Hanwoo blastocysts were simultaneously examined, fast developed embryos were indicated the better resistance to freezing than delayed developed one, irrespective of embryo containers (early; 57.1 ＆ 24.4%, expanded; 84.7 ＆ 60.6%, early hatching; 91.7 ＆ 80.0%) (P＜0.001). Especially, in expanded and early hatching blastocysts, embryo survival of V-G group (67.8, 95.0%) was significantly higher than those of V-S group (53.0, 65.0%) at 48 h post warming, respectively (P＜0.05, P＜0.001). Therefore, this study indicates that Hanwoo blastocysts can be cryopreserved more simple, efficient and successful by vitrification method using EM grid.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.217-221
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• 2013

This study developed predictive models for the kinetic behavior of Staphylococcus aureus on processed cheeses. Mozzarella slice cheese and cheddar slice cheese were inoculated with 0.1 ml of a S. aureus strain mixture (ATCC13565, ATCC14458, ATCC23235, ATCC27664, and NCCP10826). The inoculated samples were then stored at $4^{\circ}C$ (1440 h), $15^{\circ}C$ (288 h), $25^{\circ}C$ (72 h), and $30^{\circ}C$ (48 h), and the growth of all bacteria and of S. aureus were enumerated on tryptic soy agar and mannitol salt agar, respectively. The Baranyi model was fitted to the growth data of S. aureus to calculate growth rate (${\mu}_{max}$; ${\log}CFU{\cdot}g^{-1}{\cdot}h^{-1}$), lag phase duration (LPD; h), lower asymptote (log CFU/g), and upper asymptote (log CFU/g). The growth parameters were further analyzed using the square root model as a function of temperature. The model performance was validated with observed data, and the root mean square error (RMSE) was calculated. At $4^{\circ}C$, S. aureus cell growth was not observed on either processed cheese, but S. aureus growth on the mozzarella and cheddar cheeses was observed at $15^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$. The ${\mu}_{max}$ values increased, but LPD values decreased as storage temperature increased. In addition, the developed models showed acceptable performance (RMSE = 0.3500-0.5344). This result indicates that the developed kinetic model should be useful in describing the growth pattern of S. aureus in processed cheeses.

• Journal of Distribution Research
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• v.17 no.2
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• pp.93-115
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• 2012

This study empirically examines the impact of changes in market shares among retailing types on the price index. The retailing type is classified into 6 groups: department store, big mart, super market, convenient store, specialty merchant, and on-line store. The market shares of retailing types are calculated by the ratio of each retailing type monthly sales to total monthly retailing sales in which total retailing sales is the sum of each retailing type sales. We employed several price indices: consumer price index (CPI), CPI for living necessaries, and fresh food price index. In addition, this study used fundamental price indices based on 25 product families as well as 42 representative products. The empirical model also included several variables in order to control for the macroeconomic effects and those variables are the exchange rate, M1, an oil price, and the industrial production index. The data is monthly time-series data spanning over the period from January 2000 to December 2010. In order to test for the stability of data series, we conducted ADF test and PP test in which the model and length of lag were determined by the relevant previous literature and based on the AIC. The empirical results indicate that changes in market shares among retailing types have impacts on the price index. Table A shows that impacts differ as to which price index to use and which product families and products to use. For department store, it lowers the price of food and non-alcoholic beverages, home appliances, fresh food, fresh and vegetables, but it keeps the price high for fresh fruit. The big mart retailing type has a positive impact on the price of food, nut has a negative effect on clothing and foot wear, non-food, and fresh fruit. For super market, it has a positive impact on food and non-alcoholic beverages, fresh food, fresh shellfishes, but increases the price of CPI for living necessaries and non-food. The specialty merchant retailing type increases the price level of CPI for living necessaries and fresh fruit. For on-line store type, it keeps the price high for CPI for living necessaries and non-food as well as fresh fruit. For the analysis based on 25 product families shows that changes in market shares among retailing types also have different effects on the price index. Table B summarizes the different results. The 42 representative product level analysis is summerized in Table C and it indicates that changes in market shares among retailing types have different effects on the price index. The study offers the theoretical and practical implication to these findings and also suggests the direction for the further analysis.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.223-232
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• 1984

The influences of some factors involved in removing glucose from egg white by the glucose oxidase system be fore drying were investigated. And the properties between foams prepared from raw and enzyme-treat ed egg white was compared. The results obtained we re summarized as follows; 1. The dianisidine method was found to be suitable for the measurement of egg white glucose in the range up to 100ug/ml. 2. The optimal pH of glucose oxidase activity on glucose was found to be a bout 5.0, and thats activity was most stable in the pH range of about 4.0~5.0 when that enzyme was treat ed for 30 minute at $50^{\circ}C$. 3. The optimal temperature for glucose oxidase reaction on glucose was found to be about $20^{\circ}C$, and that enzyme activity was s table up to $50^{\circ}C$. 4. The removing rate of glucose from egg white with glucose oxidase was influenced by the enzyme concentration, pH and oxygen addition, and the react ion time of the desugarization was about 10 hour sunder the conditions of 0.5% hydrogen peroxide, pH 7.0 and $26^{\circ}C$. 5. All of the each egg white treated with glucose oxidase, glucose oxidase+pancreatin, glucose oxidase+trypsin showed highly foaming ability than that of natural egg white(control), but thats foam stability, on the contrary, was reversed.

• Korean journal of communication and information
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• v.27
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• pp.247-282
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• 2004

The purpose of this study is to examine the mobile phone service usage patterns of Korean teenagers and their motivation to use it, and to explore the relationships between the teenagers' social-psychological characteristics and their trails of mobile phone usage. After reviewing prior theoretical studios, three hypotheses regarding the research questions shown above were generated. Questionnaire study was conducted with 400 high school students in Busan and Ulsan metropolitan areas. They were to answer three categories of questions, such as frequencies of voice calls and text messaging services and the other mobile services, questions asking their social-psychological characteristics, and their motivations for using mobile phone services. Findings show that the teenagers more likely to tend to use voice calls when communicating family members. They tend to avoid those services with high rate of use as multimedia, game, and broadcasting services via mobile phones. The teenagers use mobile phone services for the similar purposes to conventional telephone uses. Therefore, the classical theories showing the alternative purposes or motivations to use conventional telephone usage, which divided the main purposes for phone uses in to two; work/instrumental and socializing/entertaining, proved to be reasonable. The cheap messaging services with texts are popular among the teenagers and are used for socializing/entertaining purposes rather than instrumental/functional purposes. In addition, the teenagers' social-psychological characteristicss are significantly associated with the amount of mobile phone uses. A characteristic of "individual-centeredness" is positively related with non-voice service uses, while "group-centeredness" explains heavy amount of using voice calls and text messaging services. Such characteristics as "immediacy," "directness," "innovativeness," and "other-direction" are positively associated with the frequencies and amounts of mobile phone uses, while "inner-direction" and "tradition-direction" are negatively correlated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.136-152
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• 2017

The thermodynamic models, PC-SAFT (Perturbed-Chain Statistical Associated Fluid Theory) state equation and the Two-model approach liquid activity coefficient model NRTL (Non Random Two Liquid) + Henry + Peng-Robinson, for modeling the Rectisol process using methanol aqueous solution as the $CO_2$ removal solvent were compared. In addition, to determine the new binary interaction parameters of the PC-SAFT state equations and the Henry's constant of the two-model approach, absorption equilibrium experiments between carbon dioxide and methanol at 273.25K and 262.35K were carried out and regression analysis was performed. The accuracy of the newly determined parameters was verified through the regression results of the experimental data. These model equations and validated parameters were used to model the carbon dioxide removal process. In the case of using the two-model approach, the methanol solvent flow rate required to remove 99.00% of $CO_2$ was estimated to be approximately 43.72% higher, the cooling water consumption in the distillation tower was 39.22% higher, and the steam consumption was 43.09% higher than that using PC-SAFT EOS. In conclusion, the Rectisol process operating under high pressure was designed to be larger than that using the PC-SAFT state equation when modeled using the liquid activity coefficient model equation with Henry's relation. For this reason, if the quantity of low-solubility gas components dissolved in a liquid at a constant temperature is proportional to the partial pressure of the gas phase, the carbon dioxide with high solubility in methanol does not predict the absorption characteristics between methanol and carbon dioxide.

• Food Science of Animal Resources
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• v.26 no.1
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• pp.37-42
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• 2006

The current study was conducted to investigate the effect of types of crate and season on transport condition and mortality, and ultimately to identify the best practice for reducing economic lose. Total loading weight stocking density, transport and lairage times and mortality were surveyed from the management data sheet of two companies for each first week of January, April, August and October, An average loading weight, length of transport and lairage times and mortality were 3.9 ton, 96 min, 478 min and 0.6%, respectively. Mortality after lairage was not significant between two types of crate. In addition, container type crate showed higher loading weight and stocking density than box type one. Spring and winter had significantly higher mortality with 0.7 and 0.8%, respectively, then summer and fell of 0.5%. An interaction between crate type and season on mortality showed that mortality for box type on was higher in spring and winter with 0.8 and 0.7%, respectively, compared to summer and fall of 0,3 and 0.4% respectively. In the case of container type crate, spring, fall and winter had greatly different death into with 0.7, 0.5 and 0.8%, respectively, while there was no difference between spring and summer, and between summer and winter, Mortality after transportation was similar between both crate type, with higher rate for spring and winder than other seasons. The result was likely related to death of exposure due to extended waiting time without heating facility.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.374-385
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• 2013

Sediment particle motions have been numerically simulated over a sinusoidal ripple. Turbulent boundary layer flows are generated by Large Eddy Simulation, and the sediment particle motions are simulated using Lagrangian particle tracking method. Two unsteady flow conditions are used in the experiment by employing two different wave amplitudes while keeping other conditions such as wave period same. As expected, the amount of suspended sediment particles is clearly dependent on the wave amplitude as it is increasing with increasing flow intensity. However, it is also observed that the pattern of suspension may be different as well due to the only different condition caused by wave amplitude. Specially, the time of maximum sediment suspension within the wave period is not coincident between the two cases because sediment suspension is strongly affected by the existence of turbulent eddies that are formed at different times over the ripple between the two cases as well. The role of these turbulent eddies on sediment suspension is important as it is also confirmed in previous researches. However, it is also found the time of these eddies' formation may also dependent on the wave amplitude over rippled beds. Therefore, it has been proved that various flow as well as geometric conditions under waves has to be considered in order to have better understanding on the sediment suspension process over ripples. In addition, it is found that high turbulent energy and strong upward flow velocities occur during the time of eddy formation, which also supports high suspension rate at these time steps. The results indicate that the relationship between the structure of flows and bedforms has to be carefully examined in studying sediment suspension at coastal regions.