• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.171-177
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• 2007

In order to investigate the effect of the methanogenic bacteria in bacteria in leachate on the degradability of landfill waste, this study has created 4 cylinder-shape PVC lysimeters (Diameter: 30cm, Height: 200cm, Volume: 140L) and for the biological treatment and recirculation of the leachate, two anaerobic batch reactors (Diameter: 20cm, Height: 30cm) were created. To simulate a conventional landfill, no recycling was done in L1. In L2, 1,068ml of leachate (twice of rainfall amount) was recycled. In L3 and L4, the leachate was anaerobically digested in a dark room (with $35{\pm}1^{\circ}C$) for a week and them recycled by 1,064ml and 2,128ml, respectively, with recycled water only. In terms of cumulative $CH_4$ production, however, L3 and L4 were much higher (three times) than L1 and L2. Between L3 and L4, the latter was 1.23 times higher than the former in terms of cumulative CH4 production. In other words, the more the methanogenic bacteria-activated leachate is recycled, the more active the degradation due to active methane fermentation by the recyled methanogenic bacteria. And methane recovery is different according to the amount of recycled the methanogenic bacteria in leachate.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.409-416
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• 1993

After spraying simulated sulphuric acid rain (SSAR) to the leaves of Glycine max, Quercus aliena var. pellucida and Pinus rigida, the leachates were consecutively collected and quantitatively determined for the concentration of K and Ca. The amount of the leached ion decreased with subsequent acid treatment for all plants. But as the pH of SSAR decreased, the amount of the leached ion increased. The cumulative quantities of K leached from each species were 1.04 to 1.46 times higher at pH 4.0, 1.09 to 1.58 times higher at pH 3.5 and 1.24 to 2.03 times higher at pH 3.0 compared with pH 5. 6 treatments. The cumulative quantities of Ca leached from each species were 1.23 to 1.47 times higher at pH 4.0, 1.50 to 1.92 times higher at pH 3.5, and 2.45 to 3.30 times higher at pH 3.0 compared with pH 5.6 treatments. The Ca /K ratio in 1000 ml leachate was 1.10 to 2.91 for Q. aliena var. pellucida and 1.68 to 2.98 for P. rigida, but 0.66 to 0.91 for G, max. The Ca /K ratio in 1000 rnl leachate increased for all three species, as the pH of SSAR decreased. Foliage analysis after acid rain treatment showed leaching effect at pH 3.0.

• The Korean Journal of Financial Management
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• v.25 no.2
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• pp.191-213
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• 2008

This study tests and reconfirms the wealth transfer of mergers and acquisitions(M&As) by examining the changes in and the relationship between shareholder and bondholder wealth after the announcements of M&As for the publicly listed firms in Korea Stock Exchange and KOSDAQ market during $1999{\sim}2006$. The change in shareholder wealth is measured by the Cumulative Abnormal Return(CAR) at the M&A announcements, and the change in bondholder wealth is calculated using the Yield Spread Change(YSC) and the change in acquiring firms' credit ratings. The empirical tests show that the CAR of 344 sample acquiring firms at the announcement is 3.59%, which confirms results of the prior research on M&As in Korean market. The average YSC for 35 sample acquiring firms between $2001{\sim}2006$ proves to be negative when we use the yield spread of firms with comparable credit ratings as a benchmark, which means that the acquiring firms' bondholders gain with the announcements of M&As. We find the same result using another benchmark-the yield spread of government bonds. The improvement in the acquiring firms' credit ratings one year after the M&As also indicates that the M&As, on average, increase bondholder wealth. Our test results are consistent with those of the existing studies on the effect of bondholder wealth after the M&As in the United States, which shows that the bondholder wealth increases after the M&As. We do not find the evidence that there is a wealth transfer from the acquiring firms' bondholders to the shareholders after the M&A announcements. Rather, this study confirms that the wealth of the acquiring firms' bondholders increases in the M&As in Korea.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.326-336
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• 1997

Four ice nucleation-active bacteria (INA-bacteria), Pseudomonas syringae, Xanthomonas campestris, Escherichia coli JM109/pEIN229 and Gluconobacter oxydans/pKIN230, were treated with heat, pressure and gamma-irradiation to compare viability and their ice nucleation activity (INA) after sterilization. Gamma-irradiated INA-bacteria showed the least decrease in T90 value (the temperature at which the 90% of drops are frozen). According to cumulative INA spectra, gamma-irradiated INA-bacteria showed little decrease in class A ice nuclei $(nucleate\;H_{2}O\;at\;higher\;than\;-5^{\circ}C)$, pressurized INA-bacteria showed more than 90% decrease in class A ice nuclei, and heat-treated INA-bacteria barely showed class A ice nuclei. Differential scanning calorimetry (DSC) was used to examine the effect of INA-bacteria on the thermophysical properties of water at freezing temperature. Freezing peaks were appeared at about $11{\sim}15^{\circ}C$ higher on thermograms and enthalpies of phase change were decreased for the water containing INA-bacteria compared with the pure water, while melting peaks were not shifted. INA measured by DSC method were significantly correlated with INA measured by drop freezing method $(R^{2}>0.993,\;p<0.0001)$, indicating that DSC can be used as a new, simple and precise method for measuring INA.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.12-17
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• 2002

Tn establish the criteria for appropriate seedling production method in the summer, the effect of container size and seedling age on the growth and yield were evaluated with tomato. The seedling quality was higher when seedlings were grown polyethylene in 9cm pots than in 72 cell plugs. Seedling quality increased with increase in seedling age in polyethylene pots, whereas seedling age did not affect seedling quality in plug trays. Fruits matured earlier on plants started from pot-grown transplants for a long duration than with plug tray-grown transplants for a shorter duration. Not only total yield in 4 months, but the early yield in the first 2 months, was higher with pot-nursed transplants than with plug tray-nursed transplants. With pot-grown transplants, The early yield in initial 2 months was the lowest in 25 day-old transplants, whereas there was no significant differences between 35- and 45-day-old transplants. Seedling age did not affect the cumulative yield for 3 months after the first harvest. With plug tray-grown transplants, the cumulative yield tar initial 3 months was the highest in plants grown for 35 days in the nursery, followed by 25 day and 45 day. However, there were no significant differences among seedling ages in the total yield.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.616-627
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• 1998

In order to evaluate the cytogenetic hazard among hospital workers potentially exposed to low dose of radiation, the analysis of chromosome aberrations(CA) and sister chromatid exchanges(SCE) in lymphocytes were performed in 79 hospital workers and 79 non-exposed workers. The mean frequency of chromosomal exchange and deletion(respectively, $0.20\times10^{-2}/cell\;and\;0.39\times10^{-2}/cell$) in the exposed group were significantly higher than those$(0.07\times10^{-2}/cell\;and\;0.23\times10^{-2}/cell)$ in control group. The frequency of sister chromatid exchanges was 5.04/cell in the control vs. 6.57/cell in the exposed group. There were also significant differences in the mean frequencies of CA and SCE adjusted for age, sex, smoking, drinking between two groups. There were no evidence of significant increase of CA and SCE according to the department or duration of employment. But the frequency of cells having chromosome aberration was significantly higher in the exposed group than in the control group related to duration of employment. There was no dose-effect relationship between the cumulative doses and the frequency of CA and SCE. But in the case of last 1 yr cumulative dose, there were evidence of significant dose-dependant increase of chromosome type CA and percentage of cells with aberration. The result suggest that there is cytogenetic hazard in risk group like hospital workers handling low dose radiation. And the analysis CA and SCE are useful biological indicators for the exposure of low dose level of radiation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.340-347
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• 2015

This study was conducted to analyze the relationship between climate factors and fruit characteristics of 'Sangjudungsi' persimmon (Diospyros kaki THUNB) has been mainly cultivated in Sangju of Korea. We has been surveyed the yield and fruit characteristics such as fruit weight and soluble solids of 'Sangjudungsi' persimmon from 2010 to 2015 for five years. Also, as major meteorological factor, mean air temperature, cumulative temperature and days, the data of sunshine duration, diurnal range, and rainfall were collected from Sangju Regional Meteorological Administration. As result of that, the annual variation of fruit weight was affected by sunshine duration for April and October related starting point of fruit weight increase. The content of soluble solids was affected by sunshine duration for April and October similarly with fruit weight and was negatively correlated with the number of days with precipitation in the year. These results indicate the characteristics related to fruit quality like the above were affected by the sunshine duration and precipitation which is critical factor for the intensity of radiation during rapid growth period (April and October). Fruit number and yield per tree was commonly affected by mean air temperature of April and cumulative temperature days of October. These results also indicate that temperature for period of rapid growth stage of persimmon may have an important role in the fruit number and yield per tree.

• Journal of Applied Biological Chemistry
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• v.54 no.4
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• pp.296-302
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• 2011

Insect-resistant transgenic rice was developed by inserting the mCry1Ac1 a modified gene from the soil bacterium Bacillus thuringiensis (Bt). For biosafety assessment, we studied the effects on survival of cantor Daphnia magna, a commonly used as a model organism in ecotoxicological studies. D. magna fed on Bt rice and its near non-genetically modified (GM) counterparts (Nakdong) grown in the same environment (100% ground rice suspension). The Bt rice was comfirmed to have the insertion of T-DNA and protein expression by the polymerase chain reaction and ELISA analysis. Feeding study showed similar cumulative immobility and abnormal response of D. magna between Bt rice and non-GM counterparts. 48 h-$EC_{50}$ values of Bt rice and non-GM rice showed 4,429 and 2,889 mg/L respectively. The rice no observed effect concentration (NOEC) values for D. magna was suggested 1,000 mg/L. We conclude that the tested Bt-rice and Nakdong similar cumulative immobility for D. magna the widely used model organism. We found out that there is strong possibility that the growth of Bt rice didn't affect to non-target insects.

• Journal of Korean Academy of Nursing
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• v.4 no.1
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• pp.121-134
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• 1974

This study is an attempt to evaluate the use of an oral contraceptive by: 1. Deforming the acceptance rate of the oral contraceptive according to socio-demographic characteristics 5. Estimating the duration of the use of the contraceptive f. Discovering reasons why the contraceptive was discontinued 4. Computing the cumulative continuation and discontinuation rate according to socio-demographic characteristics, history of pregnancies, and attitude of husband at the time of selection of the contraceptive. One hundred sixty-eight women of child bearing age (14-49 years), residing in Yonhee Dong, Seoul, Korea and registered as oral contraceptive accepters at Yonsei Community Health Center, were interviewed during a three week period in 1973. The questionnaire was designed to determine the socio-demographic characteristics of the oral contraceptive accepters, the current status of their family planning practice, medical reactions if any, discontinuation practice, and the duration of the use of the contraceptive. The major findings of the study were as follows; 1. The acceptance rate was highest for women between 30 and 34 years of age, the mean age being 34.4 years. 2. Fifty six point five percent of all respondents said that thirty years of age was the ideal age to stop having children. 3. The average number of living children was 3.5 and fifty four point eight percent of respondents felt 2 boys and I girl was the ideal number of children. 4. The average number of pregnancies was 5.2 and the average number of induced abortion was I. 4. 5. Fifty eight point eight percent of the respondents had experience in the use of contraceptive methods in the past. 6. Forty one point seven percent of the respondents replied that they chose the oral contraceptive because, "it was not complicated to use." 7. Sixty four point eight percent of the women said their husband approved of their taking the pill. 8. The cumulative discontinuation rate was sixty point five percent of the total respondents for one year in first segment. 9. Sixty six point nine percent of the respondents had experienced side-effect while using the pill. The side effects for 68.9 percent of these women were castro-intestinal upsets. Twenty point eight percent of the women who had side effects consulted with medical personnel about them. Women who had more education had more side effects. 10. Seventy three point two percent of the women who discontinued the pill did so because of medical reasons. Women who were younger discontinued the pill for personal reasons more-often than older women. Among personal reasons listed for discontinuing the pill was the attitude of the husband. 11. The average duration of continuance of the contraceptive was 5.3 cycles under 29 years of age; 7.4 cycles between 30 and 34 years of age; and 8.4 cycles over 40 years of age. 12. The discontinuation rate was seem to increase sharply in the early cycle and increase more slowly in later cycle. Conclusions and suggestions: Since the attitude of the husband was shown to be important, the current family planning program should be expended to include approach to husband. For women who must use the oral contraceptive, education and support must be enhanced so that the discontinuation rate due to side effects will be decreased.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.363-369
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• 2006

Effects of three packing materials and exposure time on the mortality of Plodia interpunctella and Tribolium castaneum were studied using $CO_{2}-modified$ atmosphere control. Materials used were triple layered craft paper (KKK), triple layered craft paper with one laminate coating layer (KLK), and triple layered craft paper with one HD film coating layer (KHK). In the test balls (${\phi}1.2\;m$) containing 85% $CO_{2}-modified$ atmosphere, concentration of $CO_{2}$ in small packing envelopes ($9.8{\times}9.8cm$) made of the materials after one day was higher in KKK ($26.67{\pm}0.58%$) than KLK ($23.33{\pm}0.58%$) or KHK ($20.67{\pm}0.58%$). Both P. interpunctella and T. castaneum showed higher mortality in KKK than in either KLK or KHK Similar results were obtained by larger space ($9{\times}4{\times}3m$) and packing volume (20 kg) studies. The effect of the packing materials was clearer on T. castaneum more tolerant to $CO_{2}$ than P. interpunctella. Regression of the insect mortality on cumulative concentration time (${\int}_{0}^{t}c{\times}tdc{\approx}{\sum}concentration{\times}time$) was highly significant. Control of P. interpunctella and T. castaneum by $CO_{2}-modified$ atmosphere were discussed in relation to packing materials, cumulative concentration time of $CO_{2}$ and food products.