• Atmosphere
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• v.21 no.4
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• pp.349-359
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• 2011

The climatology in stratospheric ozone over the Korean Peninsula, presented in previous studies (e.g., Cho et al., 2003; Kim et al., 2005), is updated by using daily and monthly data from satellite and ground-based data through December 2009. In addition, long-term satellite data [Total Ozone Mapping Spectrometer (TOMS), Ozone Monitoring Instrument (OMI), 1979~2009] have been also analyzed in order to deduce the spatial distributions and temporal variations of the global total ozone. The global average of total ozone (1979~2009) is 298 DU which shows a minimum of about 244 DU in equatorial latitudes and increases poleward in both hemispheres to a maximum of about 391 DU in Okhotsk region. The recent period, from 2006 to 2009, shows reduction in total ozone by 6% relative to the values for the pre-1980s (1979~1982). The long-term trends were estimated by using a multiple linear regression model (e.g., WMO, 1999; Cho et al., 2003) including explanatory variables for the seasonal variation, Quasi-Biennial Oscillation (QBO) and solar cycle over three different time intervals: a whole interval from 1979 to 2009, the former interval from 1979 to 1992, and the later interval from 1993 to 2009 with a turnaround point of deep minimum in 1993 is related to the effect of Mt. Pinatubo eruption. The global trend shows -0.93% $decade^{-1}$ for the whole interval, whereas the former and the later interval trends amount to -2.59% $decade^{-1}$ and +0.95% $decade^{-1}$, respectively. Therefore, the long-term total ozone variations indicate that there are positive trends showing a recovery sign of the ozone layer in both North/South hemispheres since around 1993. Annual mean total ozone (1985~2009) is distributed from 298 DU for Jeju ($33.52^{\circ}N$) to 352 DU for Unggi ($42.32^{\circ}N$) in almost zonally symmetric pattern over the Korean Peninsula, with the latitudinal gradient of 6 DU $degree^{-1}$. It is apparent that seasonal variability of total ozone increases from Jeju toward Unggi. The annual mean total ozone for Seoul shows 323 DU, with the maximum of 359 DU in March and the minimum of 291 DU in October. It is found that the day to day variability in total ozone exhibits annual mean of 5.7% in increase and -5.2% in decrease. The variability as large as 38.4% in increase and 30.3% in decrease has been observed, respectively. The long-term trend analysis (e.g., WMO, 1999) of monthly total ozone data (1985~2009) merged by satellite and ground-based measurements over the Korean Peninsula shows increase of 1.27% $decade^{-1}$ to 0.80% $decade^{-1}$ from Jeju to Unggi, respectively, showing systematic decrease of the trend magnitude with latitude. This study also presents a new analysis of ozone density and trends in the vertical distribution of ozone for Seoul with data up to the end of 2009. The mean vertical distributions of ozone show that the maximum value of the ozone density is 16.5 DU $km^{-1}$ in the middle stratospheric layer between 24 km and 28 km. About 90.0% and 71.5% of total ozone are found in the troposphere and in the stratosphere between 15 and 33 km, respectively. The trend analysis reconfirms the previous results of significant positive ozone trend, of up to 5% $decade^{-1}$, in the troposphere and the lower stratosphere (0~24 km), with negative trend, of up to -5% $decade^{-1}$, in the stratosphere (24~38 km). In addition, the Umkehr data show a positive trend of about 3% $decade^{-1}$ in the upper stratosphere (38~48 km).

• Clinical and Experimental Pediatrics
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• v.52 no.12
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• pp.1337-1347
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• 2009

Purpose:Taurine (2-aminoethanesulfonic acid) is a simple sulfur-containing amino acid. It is abundantly present in tissues such as brain, retina, heart, and skeletal muscles. Current studies have demonstrated the neuroprotective effects of taurine, but limited data are available for such effects during neonatal period. The aim of this study was to determine whether taurine could reduce hypoxic-ischemic (HI) cerebral injury via anti-apoptosis mechanism. Methods:Embryonic cortical neurons isolated from Sprague-Dawley (SD) rats at 18 days gestation were cultured in vitro. The cells were divided into hypoxia group, taurine-treated group before hypoxic insult, and taurine-treated group after HI insult. In the in vivo model, left carotid artery ligation was performed in 7-day-old SD rat pups. The pups were exposed to hypoxia, administered an injection of 30 mg/kg of taurine, and killed at 1 day, 3 days, 1 week, 2 weeks, and 4 weeks after the hypoxic insult. We compared the expressions of Bcl-2, Bax, and caspase-3 among the 3 groups by using real- time polymerase chain reaction (PCR) and western blotting. Results:The cells in the taurine-treated group before hypoxic insult, although similar in appearance to those in the normoxia group, were lesser in number. In the taurine-treated group, Bcl-2 expression increased, whereas Bax and caspase-3 expressions reduced. Conclusion:Taurine exerts neuroprotective effects onperinatal HI brain injury due to its anti-apoptotic effect. The neuroprotective effect was maximal at 1-2 weeks after the hypoxic injury.

• Clinical and Experimental Pediatrics
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• v.51 no.10
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• pp.1102-1111
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• 2008

Purpose : Resveratrol, extracted from red wine and grapes, has an anti-cancer effect, an antiinflammatory effect, and an antioxidative effect mainly in heart disease and also has neuroprotective effects in the adult animal model. No studies for neuroprotective effects during the neonatal periods have been reported. Therefore, we studied the neuroprotective effect of resveratrol on hypoxic-ischemic brain damage in neonatal rats via anti-apoptosis. Methods : Embryonic cortical neuronal cell culture of rat brain was performed using pregnant Sprague-Dawley (SD) rats at 18 days of gestation (E18) for the in vitro approach. We injured the cells with hypoxia and administered resveratrol (1, 10, and $30{\mu}g/mL$) to the cells at 30 minutes before hypoxic insults. In addition, unilateral carotid artery ligation with hypoxia was induced in 7-day-old neonatal rats for the in vivo approach. We injected resveratrol (30 mg/kg) intraperitoneally into animal models. Real-time PCR and Western blotting were performed to identify the neuroprotective effects of resveratrol through anti-apoptosis. Results : In the in vitro approach of hypoxia, the expression of Bax, caspase-3, and the ratio of Bax/Bcl-2, indicators of the level of apoptosis, were significantly increased in the hypoxia group compared to the normoxia group. In the case of the resveratrol-treated group, expression was significantly decreased compared to the hypoxia group. And the results in the in vivo approach were the same as in the in vitro approach. Conclusion : The present study demonstrates that resveratrol plays neuroprotective role in hypoxic-ischemic brain damage during neonatal periods through the mechanism of anti-apoptosis.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.5 no.4
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• pp.1-34
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• 2010

Recently, failure rates of Kosdaq IPO firms are increasing and their survival rates tend to be very low, and when these firms do fail, often times backed by a number of governmental financial supports, they may inflict severe financial damage to investors, let alone economy as a whole. To ensure investors' confidence in Kosdaq and foster promising and healthy businesses, it is necessary to precisely assess their intrinsic values and survivability. This study investigates what contributed to the failure of IPO firms and analyzed how these elements are factored into corresponding firms' stock returns. Failure risks are assessed at the time of IPO. This paper considers factors reflecting IPO characteristics, a firm's underwriter prestige, auditor's quality, IPO offer price, firm's age, and IPO proceeds. The study further went on to examine how, if at all, these failure risks involved during IPO led to post-IPO stock prices. Sample firms used in this study include 98 Kosdaq firms that have failed and 569 healthy firms that are classified into the same business categories, and Logit models are used in estimate the probability of failure. Empirical results indicate that auditor's quality, IPO offer price, firm's age, and IPO proceeds shown significant relevance to failure risks at the time of IPO. Of other variables, firm's size and ROA, previously deemed significantly related to failure risks, in fact do not show significant relevance to those risks, whereas financial leverage does. This illustrates the efficacy of a model that appropriately reflects the attributes of IPO firms. Also, even though R&D expenditures were believed to be value relevant by previous studies, this study reveals that R&D is not a significant factor related to failure risks. In examing the relation between failure risks and stock prices, this study finds that failure risks are negatively related to 1 or 2 year size-adjusted abnormal returns after IPO. The results of this study may provide useful knowledge for government regulatory officials in contemplating pertinent policy and for credit analysts in their proper evaluation of a firm's credit standing.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.5
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• pp.127-139
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• 2017

In recent 10 years the attention to social entrepreneurship has raised increasing among scholars, public sector, and community development. However less research has been conducted on how social entrepreneurship intention create a social enterprise and what factors can be affected to the social entrepreneurial intentions. This paper aims at contributing to identify the antecedents of entrepreneurial behavior and intentions. Especially, we have had a strong interests in compassion factors which haven't been used as important variables to encourage for people to do social entrepreneurial activities. Also, we try to find the moral obligation and perceived social support as antecedents of social entrepreneurial intentions. Finding show that compassion and moral obligation affect to the social entrepreneurial intention. Especially this study identify the external factor of society with the variable, perceived social support. Once individuals recognize that the infrastructure and societal positive mood on social entrepreneurship is friendly to social entrepreneurship, people have a tendency to try to do some social entrepreneurial activities. Only few empirical studies exist in this research domain. A study of more than 271 Korean college students has studied which personal traits predict certain characteristics of social entrepreneurs (such as having social vision or looking for social innovational opportunities). In addition to those antecedents, students experience is the critical factor that enabled continued expansion of the social entrepreneurial activities. The results of this research show how we can nurture social entrepreneurs and how we can develop the social environment to promote social entrepreneurship.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.171-179
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• 1999

The $CO_2$-rich waters in the Chojeong area are characterized by low pH (5.0~5.8), high $CO_2$pressure (about 1 atm) and high amounts of total dissolved iou (up to 989 mg/L) and chemically belong to Ca-HC $O_3$type. The oxygen. deuterium and tritium isotope data indicate that the mixing process occurred between $CO_2$-rich water and surface water and/or shallow groundwaters and also suggest that the $CO_2$-rich water has been derived from meteoric waters. According to $\delta$$^{13}$ C values (-8.6~-5.3$\textperthousand$). the $CO_2$ in the water is attributed from deep seated $CO_2$gas. The high dissolved carbon (-14.4~-6.8$\textperthousand$. $\delta$$^{13}$ C) in groundwater of the granitic terrain might be affected by $CO_2$-rich water, whereas the dissolved carbon (-17.9~-15.2$\textperthousand$. $\delta$$^{13}$ C) in groundwater of the metamorphic terrain is likely controlled by soil $CO_2$ and from the reaction with calcite in phyllite. Sulfur isotope data (＋3.5~＋11.3$\textperthousand$,$\delta$$^{34}$ $S_{SO4}$) also support the mixing process between $CO_2$-rich water and shallow groundwater. Strontium isotopic ratio ($^{87}$ Sr/$^{86}$ Sr) indicates that the $CO_2$-rich water (0.7138~0.7156) is not related to vein calcite (0.7184) of Buak mine or calcite (0.7281~0.7346) in phyllite. By nitrogen isotope ($\delta$$^{15}$ $N_{NO3}$) the sources of nitrogen (up to 55.0 mg/L, N $O_3$) in the $CO_2$-rich water are identified as fertilizer and animal manure. It also indicates the possibility of denitrification during the circulation of nitrogen in the Chojeong area. The possible evolution model of the $CO_2$-rich water based on the hydrochemical and environmental isotopic data was proposed in this study. The $CO_2$-rich waters from the Chojeong area were primarily derived from the reaction with granite by supply of deep seated $CO_2$. and then the $CO_2$-rich water was mixed and diluted with the local groundwater.ter.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.87-97
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• 2018

The cesium (Cs) removal from the contaminated water system has been considered to be difficult because the cesium likes to exist as soluble phases such as ion and complexes than the solid in water system. Many researches have focused on developing the breakthrough adsorbent to increase the cesium removal efficiency in water. In this study, the laboratory scale experiments were performed to investigate the feasibility of the adsorption process using the bamboo charcoal for the Cs contaminated water system. The Cs removal efficiency of the bamboo charcoal were measured and the optimal adsorption conditions were determined by the adsorption batch experiments. Total 5 types of commercialized bamboo charcoals in Korea were used to identify their surface properties from SEM-EDS and XRD analyses and 3 types of bamboo charcoals having large specific surface areas were used for the adsorption batch experiment. The batch experiments to calculate the Cs removal efficiency were performed at conditions of various Cs concentration (0.01 - 10 mg/L), pH (3 - 11), temperature ($5-30^{\circ}C$), and adsorption time (10 - 120 min.). Experimental results were fitted to the Langmuir adsorption isotherm curve and their adsorption constants were determined to understand the adsorption properties of bamboo charcoal for Cs contaminated water system. From results of SEM-EDS analyses, the surfaces of bamboo charcoal particles were composed of typical fiber structures having various pores and dense lamella structures in supporting major adsorption spaces for Cs. From results of adsorption batch experiments, the Cs-133 removal efficiency of C type bamboo charcoal was the highest among those of 3 bamboo charcoal types and it was higher than 75 % (maximum of 82 %) even when the initial Cs concentration in water was lower than 1.0 mg/L, suggesting that the adsorption process using the bamboo charcoal has a great potential to remove Cs from the genuine Cs contaminated water, of which Cs concentration is low (< 1.0 mg/L) in general. The high Cs removal efficiency of bamboo charcoal was maintained in a relatively wide range of temperatures and pHs, supporting that the usage of the bamboo charcoal is feasible for various types of water. Experimental results were similar to the Langmuir adsorption model and the maximum amount of Cs adsorption (qm:mg/g) was 63.4 mg/g, which was higher than those of commercialized adsorbents used in previous studies. The surface coverage (${\theta}$) of bamboo charcoal was also maintained in low when the Cs concentration in water was < 1.0 mg/L, investigating that the Cs contaminated water can be remediated up with a small amount of bamboo charcoal.

• Korean Journal of Animal Reproduction
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• v.24 no.2
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• pp.171-178
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• 2000

To improve the pig farm management and efficiency of swine industry by inducing the farrowing to day-time from night, In the first experiment, reproduction records of purebred and crossbred pigs were collected and analyzed to estimate the $\varepsilon$ ffec 잉 of factors affecting day and night farrowing. The general linear model was used to estimate the least square means of the factors affecting various reproductive characteristics. And also, chi-square tests were used to examine the independence of the reproductive traits and environmental factors using the SAS (1992). The comparisons between pure and crossbred pigs for total number born, percentage of number born alive, gestation length, time length for farrowing were determined. The results indicated that the gestation length of crossbred (115.11 d) was slightly longer than that of purebred (114.89 d, p＜0.05). For the seasonal effects on total number born, the largest was found in spring and no differences were found among summer, fall and winter. The average gestation length was 1 day longer in spring and winter than in summer and fall. The total number born and number born alive were smaller in first, second, and greater or equal to sixth parity than other parities. And also, the percentage of no. born alive was least in greater or equal to sixth parity. For the effect of mating methods, natural and artificial insemination, on total number born and number born alive, no differences between the two methods were found. However, the percentage of number born alive for natural mating was 98.06% and was higher than artificial insemination(93.75%). The time length for farrowing was I hour were found for the 6 hrs of farrowing time. In general situation of pig farms, day-time farrowing was 34.8% and night farrowing was 65.2%, indicating that night farrowing was almost double of the night farrowing.

• Applied Microscopy
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• v.35 no.1
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• pp.31-39
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• 2005

Synapses are contact points where one neuron communicates with another. The morphological change of synapses under various physiological or pathological conditions has long been hypothesized to modify their functional properties. 3-dimensional (3-D) reconstruction of synapses with serial ultrathin sections has contributed to the understanding of ultrastructural dimensions and compositions of synapses. The 3-D reconstruction procedures, however, require a great amount of expertise as well as include prohibitively timeconsuming processes. Here, we introduce efficient 3-D reconstruction technique using high-voltage electron microscopy (HVEM). Primarily, we established an optimal section thickness and staining condition to observe synaptic structures in detail under HVEM. The result showed that synaptic profiles were preserved at the section thickness of 250 nm without the overlapping of synaptic ultrastructures. An increase in the reaction time of en bloc staining was most efficient to enhance contrast than the extension of postembedding staining or the addition of uranyl acetate during dehydration. Then, 3-D reconstruction of parallel fiber-Purkinje cell synapses in the rat cerebellum was carried out with serial HVEM images and reconstruction software. The images were aligned and the contours of synapses were outlined on each section. 3-D synapses were finally extracted from the section files by grouping all the synaptic contours. The reconstructed synapse model clearly demonstrated the configuration of pre and postsynaptic components. These results suggest that 3-D reconstruction of synapses using HVEM is much efficient and suitable for massive quantitative studies on synaptic connectivity than conventional TEM approach using numerous ultrathin sections.

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.365-375
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• 1995

The anemia-inducing strain of Friend virus (FVA) is a murine retrovirus which stimulates the proliferation of erythroid progenitor cells. The progenitor cells synthesized by FVA-stimulation are unable to proceed with differentiation and accumulate in the spleen resulting in splenomegaly in infected mice. Using FVA-inoculated mice as a model, we have investigated the antiretroviral effects of 2',3'-dideoxycytidine (ddC) and recombinant $interferon-{\alpha}-A\;(rIFN-{\alpha}-A)$ on FVA infection. The extent of the infection was determined by measuring the weights of the spleens. Daily intraperitoneal injection of ddC (100 mg/kg body weight), $rIFN-{\alpha}-A$ (10 KU/mose) and the combination of both drugs to FVA inoculated mice for 18 days resulted in suppression of the growth of spleens by 15.1%, 52.7% and 61.6%, respectively. When ddC was dissolved in drinking water (0.1 mg/ml) and administered to a group of FVA inoculated mice ad libitum, and $rIFN-{\alpha}-A$ (10 KU/mouse) was intraperitoneally injected daily to another group of ddC (0.1 mg/ml) drinking mice for 18days, the growth of spleens was suppressed by 38.4% and 83.2%, respectively. These results indicate that administration of ddC via drinking water is more effective in suppressing FVA infection than the daily injection of ddC, and that the combined effects ddC and $rIFN-{\alpha}-A$ are not synergistic but additive. In order to determine whether ddC treatment alters the characteristic of the progenitor cells with respect to $Ca^{++}$ uptake, $Ca^{++}$ uptake in erythroid cells and the effect of cyclohexyladenosine (CHA) on the $Ca^{++}$ uptake were studied. $Ca^{++}$ uptake in the erythroid progenitor cells was about 20-fold greater than in mouse erythrocytes and the inhibition of $Ca^{++}$ uptake by CHA was the greatest in the progenitor cells from FVA infected mice which were treated with ddC. The inhibition was obviated by theophylline. Results of CHA binding studies showed that the erythroid progenitor cells contain both high and low affinity CHA binding sites, whereas mose erythrocytes contain only the low affinity CHA binding sites.