• Korean Journal of Social Welfare
• /
• v.68 no.4
• /
• pp.169-198
• /
• 2016

This study shows the meaning on context of social work practicum that college students have experienced. It reveals to find a essence of social work practicum based on college students through free variation. They met a "high barrier" from the beginning of social work practicum. There were "confused boundary of role as well as work". "Dilemma" has been accessed, so they felt various emotions for social work and social worker to be able to exist. "Various practice place" meant to continue as a multi-player with a weak appearance and confront for time as who he/she is. This was connected to whole life time for individually. Disclosure was as below. identity as a social worker(to be) was consisted beyond interaction between student and supervisor. Organization of social work practicum was considered when they had taken a part in. Gap must find out to be disappeared between ideal things and real things about social work practicum. Ideal type of college education for social work as well as whole education for all were needed.

• Journal of Internet Computing and Services
• /
• v.15 no.6
• /
• pp.15-26
• /
• 2014

This study focus on a economic value of the Big Data technologies by real options model using big data technology company's stock price to determine the price of the economic value of incremental assessed value. For estimating stochastic process of company's stock price by big data technology to extract the incremental shares, Generalized Moments Method (GMM) are used. Option value for Black-Scholes partial differential equation was derived, in which finite difference numerical methods to obtain the Big Data technology was introduced to estimate the economic value. As a result, a option value of big data technology investment is 38.5 billion under assumption which investment cost is 50 million won and time value is a about 1 million, respectively. Thus, introduction of big data technology to create a substantial effect on corporate profits, is valuable and there are an effects on the additional time value. Sensitivity analysis of lower underlying asset value appear decreased options value and the lower investment cost showed increased options value. A volatility are not sensitive on the option value due to the big data technological characteristics which are low stock volatility and introduction periods.

• Korean Journal of Food Science and Technology
• /
• v.29 no.5
• /
• pp.1006-1015
• /
• 1997

Whole soybean meju was fermented with four Bacillus strains for 45 hr in its model system. The pH range of the product was $7.98{\sim}8.68$, the contents of amino nitrogen and ammoniacal nitrogen were $286{\sim}439\;mg%,\;0.11{\sim}0.23%$, respectively and that of reducing sugar ranged $0.65{\sim}2.24%$. During fermentation, the enzyme activities increased up to $30{\sim}40\;hr$ of fermentation and slightly decreased after 45 hr. Stachyose was special sugar components for B. licheniformis and raffinose was for B. natto. The components of the organic acid showed distinctive patterns among four products and the patterns of amino acids and fatty acids were almost similar to those of other reports. The main and common odor concentrates of meju were pyrazine components, 3-methyl-1-butanol, acetic acid and ethanol. Chunggukjang, mixed with B. natto and B. licheniformis showed more acceptabilities than other combinations. Soybean paste, mixed with B. megaterium and B. subtilis, soysauce, mixed with B. megaterium and A. oryzae showed excellent acceptability, respectively.

• Elastomers and Composites
• /
• v.40 no.3
• /
• pp.188-195
• /
• 2005

Chemical and physical changes and the contents of functional groups in the carbon black surface after the ozone treatment was investigated using elemental analysis, pH, tint strength, DBP, $N_2SA$, IA, and acid-base reaction. As the treatment time was increased, surface structure, particle size and surface area of carbon black did not change, while surface oxygen contents increased, and pH decreased and then saturated after $1{\sim}2$ hour. The contents of carboxylic, lactone, hydroxyl, and carbonyl groups were analyzed with four bases such as $NaHCO_3,\;Na_2CO_3,\;NaOH$, and $NaOC_2H_5$. Before oxidation, the carbonyl group was dominantly present on the surface, but by increasing the treatment time, the contents of the carboxylic and carbonyl groups increased to a saturated level after $1{\sim}2$ hour. Before and after the oxidation, the lactone and hydroxyl groups were nearly absent. These results showed that the reaction mechanism of carbon black and ozone is similar to that of ethylene and ozone. Weight of oxidized carbon black was increased after treating AIBN, while free radical was slightly decreased by ESR analysis. When carbon black was treated with organic compounds containing mercapto- groups, the results of ESR showed that free radical peak intensity was almost diminished compared to original carbon black.

• Journal of Animal Science and Technology
• /
• v.50 no.3
• /
• pp.429-436
• /
• 2008

A bacterium producing cold-active cellulase and xylanase was isolated from pig feces. The isolate, DK42 strain, was found to be the Gram-positive, non-motile, catalase-positive, and spore-forming stain. Under an electron microscope, the cells were observed to be rod-shaped. The isolate was identified as Bacillus licheniformis DK42 on the basis of morphological and biochemical properties as well as 16S rRNA gene sequences. The characterization of crude cellulase and xylanase from B. licheniformis DK42 was investigated. Cellulase exhibited an optimum temperature and pH at 45℃ and 6.0, whereas xylanase exhibited an optimum temperature and pH at 55℃ and 6.0. Especially cellulase maintained approx. 50% of its maximum activity even at 10℃, indicating that it is cold-active. Both cellulase and xylanase were stable after 2hr at 35℃, whereas they lost their activities after 30min at 65℃.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.25-36
• /
• 2021

Hydrogen in hydrogen-electric vehicles has a wide range of combustion and explosion ranges, and is a combustible gas with a very fast flame propagation speed, so it has the risk of leakage, diffusion, ignition, and explosion. The fuel tank has a Thermally active Pressure Relief Device (TPRD) to reduce the risk of explosion and other explosions, and in the event of an accident, hydrogen inside the tank is released outside before an explosion or fire occurs. However, if an accident occurs in a semi-closed space such as an underground parking lot, the flow of air flow is smaller than the open space, which can cause the concentration of hydrogen gas emitted from the TPRD to accumulate above the explosion limit. Therefore, in this study, the leakage rate and concentration of hydrogen over time were analyzed according to the diameter of the nozzle of the TPRD. The diameter of the nozzle was considered to be 1 mm, 2.5 mm and 5 mm, and ccording to the diameter of the nozzle, the concentration of hydrogen in the underground parking lot increases in a faster time with the diameter of the nozzle, and the maximum value is also analyzed to be larger with the diameter of the nozzle. In underground parking lots where air currents are stagnant, hydrogen concentrations above LFL (Lowe Flammability Limit) were analyzed to be distributed around the nozzle, and it was analyzed that they did not exceed UFL (Upper Flammability Limit).

• Korean Journal of Ecology and Environment
• /
• v.54 no.4
• /
• pp.315-326
• /
• 2021

The clear-water phase (CWP) is a notable limnological phenomenon in freshwater systems caused by predatory interactions between large filter-feeding zooplankton and phytoplankton. However, the mechanisms and factors that influence the extent of CWP, particularly in complex water systems with both fluvial and lacustrine characteristics, remain poorly understood. The present study evaluated CWP occurrence patterns at different sites in a large reservoir located in a temperate monsoon region (Lake Paldang, Korea); the relationships among factors associated with CWP occurrence, such as transparency, zooplankton diversity, and chlorophyll a concentration were investigated. Transparency exhibited significant correlations with precipitation and retention time, as well as the relative abundance of zooplankton (p<0.01), suggesting that a change in the retention time due to precipitation can alter CWP. Data collected before and after CWP occurrence were analyzed using paired t-test to determine variations in CWP occurrence based on the water system characteristics. The results demonstrated that various factors were associated with CWP occurrence in the fluvial-type and lacustrine-type sites. The correlation between zooplankton biomass and transparency was stronger in the lacustrine-type sites than in the fluvial-type sites. The lacustrine-type sites, where cladoceran emergence is common and is associated with long retention times, favored CWP occurrence. The results suggest that lacustrine-type sites, which are conducive to zooplankton development and have relatively long retention times, enhance CWP occurrence. Furthermore, CWP occurrence was notable in spring, and the present study revealed that site-specific CWP could occur throughout the year, regardless of the season.

• Journal of Korea Port Economic Association
• /
• v.39 no.3
• /
• pp.191-210
• /
• 2023

The Covid-19 pandemic has had a significant impact on global logistics and supply chains, leading to major discrepancies in logistics performance across countries worldwide. Through an examination of logistics performance index and supply chain tracking data, this study aimed to identify the changes in global supply chains and logistics environments during the pandemic. The analysis of the logistics performance index showed that overall, countries around the world, especially developed nations, showed improvements in metrics such as customs and border management efficiency, the quality of trade and transport infrastructure, capability and quality of logistics services, and cargo tracking abilities. However, the competitive pricing feasibility of international transportation and the on-time delivery frequency of goods saw a decline due to the pandemic's effects. The supply chain tracking data revealed that ports in Asian countries demonstrated high processing efficiency. In contrast, the U.S. and European countries took comparatively more time. Particularly for air cargo, parcels, and express shipments, the U.S. showed relatively longer processing times, leading to logistical delays. In conclusion, during the Covid-19 pandemic, Asian countries maintained relatively high efficiency in their logistics and trade environments. Conversely, the U.S. and some European countries showed delays and decreased efficiency in various metrics. In the future, efforts should be made to address delays and congestion, namely, the deceleration of logistics processes.

• Clinical and Experimental Pediatrics
• /
• v.45 no.4
• /
• pp.473-481
• /
• 2002

Purpose : Ascending cholangitis is the most common complication after Kasai operations. The aim of this study is to evaluate the therapeutic efficacy of cefotaxime as an empirical antibiotic on ascending cholangitis after Kasai operations. Methods : Thirty-nine episodes of cholangitis in twenty-nine children who underwent Kasai operations at Seoul National University Children's Hospital from January 1991 to December 2000 were included in this study. Empirical cefotaxime treatments were divided into three groups : cefotaxime and amikacin treatment group(CA group), cefotaxime and gentamicin treatment group(CG group) and cefotaxime treatment group(C group). A diagnosis of cholangitis was made on the basis of unexplained fever(>$38^{\circ}C$) and either development of acholic stool or elevation of serum total bilirubin (>1.5 mg/dL). Therapeutic efficacy was judged by elimination of fever up to 72 hours, 120 hours, and 168 hours after antibiotic treatment. Results : There were therapeutic responses in 51%(20/39) up to 72 hours after antibiotic treatment : 54%(13/24) in CA group, 43%(3/7) in CG group and 50%(4/8) in C group. There were therapeutic responses in 69%(27/39) up to 120 hours, in 79%(31/39) up to 168 hours and in 82%(32/39) up to 2 weeks. There were no differences in therapeutic efficacy among the three regimens. In 12 of 39 episodes, the etiologic pathogens including Escherichia coli and enterococcus were cultured from the blood. Conclusion : Cefotaxime can be tried as an initial antibiotic in Korean children with ascending cholangitis after Kasai operation prior to the identification of microorganism on culture. However, further evaluation of pathogen and its resistant strain to cefotaxime should be done.

• Journal of Embryo Transfer
• /
• v.21 no.3
• /
• pp.233-239
• /
• 2006

This study was carried out to investigate the effect of intra-uterine infusion of lipopolysaccharides (LPS) on uterine involution in dairy cows with retained placenta. The LPS isolated from Bacteroides helcogenes and Fusobaoterium varium was infused at the rate of 100 ug (n=11) and 200 ug (n=11) with 30 ml of phosphate buffer saline in each cow at 20 days post-partum. The cows in conrol group (n=11) with retained placenta were infused with 30 ml phosphate buffer saline in each cow at 20 days postpartum. Cross-sectional ultrasonography was performed at days 40 postpartum to examine uterine involution and exudate in the all dairy cows in study. The cows in control group have shown 45.5, 27.3 and 27.3% gravid horn with less than 30 mm (normal), $31{\sim}50mm$ (medium) and more than 51 mm (large) in diameter. Respective average values of gravid horn diameter in cows treated with LPS 200 ug were noticed 72.7, 18.2 and 9.1%. However, the gravid horn diameter in all the cows treated with 100 ug of LPS was less than 30 mm. The 18.2, 63.6 and 54.6% cows in the control, LPS 100 ug and LPS 200 ug, respectively, have shown no exudate in uterine cavity. However, the respective rates of small amount of exudate retention in uterine cavity were 45.5, 0.0, and 9.1%. Approximately 36.4% cows in all 3 treated groups have shown minute quantity of exudate. In conclusion, the LPS intra-uterine infusion promoted postpartum uterine involution in dairy cows with retained placenta.