• The Korean Journal of Financial Management
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• v.24 no.4
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• pp.201-232
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• 2007

In this study, we investigated public announcements of stock splits using the Korean Stock Market data from 2000 through 2007. The purposes of this study are to examine whether stock splits have the information contents in the Korean capital markets, and to investigate the possible cause of the market reactions. We measured the market reactions with abnormal returns, cumulative abnormal returns and cumulative average abnormal returns. For the purpose, two specific hypotheses were tested. One is 'Signalling Effects' where stock splits function as a signal through which managers transmit a favorable information for investors. The other is 'Liquidity Effects' where stock splits increase the trading convenience. We have th following results. Firstly, positive market effects were found when stock splits were announced. Secondly, there was difference in trading convenience between the high and the low split ratios. Finally, the long term performance through stock splits in the Korean capital markets was not significant.

• 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.

• Journal of Forest and Environmental Science
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• v.35 no.4
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• pp.213-222
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• 2019

Climate change has been intensifying and affecting forest ecosystems. Over the years, the intensity and frequency of climate change have increased and the effects of climate change have been aggravating due to cumulative greenhouse gases such as CO₂, which has resulted in several negative consequences, drought being the main threat among all. Drought affects forest ecosystems directly and indirectly. Insufficient soil moisture, due to drought, may affect the growth of plants and soil respiration (SR), and soil temperature may increase because of desiccated soil. In addition, the mortality rate of plants and soil microorganisms increases. As a result, these effects could reduce forest productivity. Thus, in this article, we have presented various research studies on artificial drought using throughfall exclusion, and we have mainly focused on SR, which is significantly related to forest productivity. The research studies done worldwide were sorted as per the main groups of Köppen-Geiger climate classification and intensively reviewed, especially in tropical climates and temperate climates. We briefly reviewed the properties among the exclusion experiments about the temperate climate, which mostly includes Korean forests. Our review is not a proof of concept, but an assumption for adequate investigation of drought effects in the Korean forest.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.594-597
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• 2004

A pedigree file of 4,628 records of Muzaffarnagari sheep, maintained at Central Institute for Research on Goats (CIRG), Makhdoom, was used to calculate the inbreeding coefficient of the flock. The flock had been closed for about 25 years (1978 to 2002). The investigation was aimed to study the effects of inbreeding on survivability of lambs. The cumulative survivability of lambs i.e., lambs survived up to 3, 7 and 15 days, 1, 2, 3, 6, 9 and 12 months after birth was considered for the study. The average level of inbreeding of lambs was 1.60%, ranging from 0 to 26.4%. The average inbreeding coefficient of dam over the periods was 1.00% and it ranged from 0 to 25.0%. Significant (p<0.05) adverse effect of lamb's inbreeding was observed on survivability of lambs at all ages except up to 3 and 7 days after birth. On an average, 1% increase in individual inbreeding coefficient should reduce the 0.31, 0.34, 0.32, 0.31, 0.33, 0.44 and 0.49 percent lamb survival up to the age of 15 day and 1, 2, 3, 6, 9 and 12 months, respectively. Ewes inbreeding had non-significant effects on lamb survival at all ages.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.700-707
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• 2010

Effects of protease-resistant antimicrobial substances (PRA) produced by Lactobacillus plantarum and Leuconostoc citreum on rumen methanogenesis were examined using the in vitro continuous methane quantification system. Four different strains of lactic acid bacteria, i) Lactococcus lactis ATCC19435 (Control, non-antibacterial substances), ii) Lactococcus lactis NCIMB702054 (Nisin-Z), iii) Lactobacillus plantarum TUA1490L (PRA-1), and iv) Leuconostoc citreum JCM9698 (PRA-2) were individually cultured in GYEKP medium. An 80 ml aliquot of each supernatant was inoculated into phosphate-buffered rumen fluid. PRA-1 remarkably decreased cumulative methane production, though propionate, butyrate and ammonia N decreased. For PRA-2, there were no effects on $CH_4$ and $CO_2$ production and fermentation characteristics in mixed rumen cultures. The results suggested that PRA-1 reduced the number of methanogens or inhibited utilization of hydrogen in rumen fermentation.

• Smart Structures and Systems
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• v.22 no.4
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• pp.441-457
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• 2018

Characteristic parameter values of seismic isolators deviate from their nominal design values due to uncertainties and/or errors in their material properties and element dimensions, etc. Deviations may increase over service life due to environmental effects and service conditions. For accurate evaluation of the seismic safety level, all such effects, which would result in deviations in the structural response, need to be taken into account. In this study, the sensitivity of the probability of failure of the structures equipped with nonlinear base isolation systems to the uncertainties in various isolation system characteristic parameters is investigated in terms of various isolation system and superstructure response parameters in the context of a realistic three-dimensional base-isolated building model via Monte Carlo Simulations. The inherent record-to-record variability nature of the earthquake ground motions is also taken into account by carrying out analyses for a large number of ground motion records which are classified as those with and without forward-directivity effects. Two levels of nominal isolation periods each with three different levels of uncertainty are considered. Comparative plots of cumulative distribution functions and related statistical evaluation presented here portray the potential extent of the deviation of the structural response parameters resulting from the uncertainties and the uncertainty levels considered, which is expected to be useful for practicing engineers in evaluating isolator test results for their projects.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.79-90
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• 2023

Existing reinforced concrete (RC) frame buildings have seismic vulnerabilities because of seismically deficient details. In particular, since cumulative damage caused by successive earthquakes causes serious damage, repair/retrofit rehabilitation studies for successive earthquakes are needed. This study investigates the repair effect of fiber-reinforced polymer jacketing system for the seismically-vulnerable building structures under successive earthquakes. The repair modeling method developed and validated from the previous study was implemented to the building models. Additionally, the main parameters of the FRP jacketing system were selected as the number of FRP layers associated with the confinement effects and the installation location. To define the repair effects of the FRP jacketing system with the main parameters, this study conducted nonlinear time-history analyses for the building structural models with the various repairing scenarios. Based on this investigation, the repair effects of the damaged building structures were significantly affected by the damage levels induced from the mainshocks regardless of the retrofit scenarios.

• Journal of Environmental Health Sciences
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• v.49 no.1
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• pp.1-10
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• 2023

Low-dose radiation exposure has received considerable attention because it reflects the general public's type and level of exposure. Still, controversy remains due to the relatively unclear results and uncertainty in risk estimation compared to high-dose radiation. However, recent epidemiological studies report direct evidence of health effects for various types of low-dose radiation exposure. In particular, international nuclear workers' studies, CT exposure studies, and children's cancer studies on natural radiation showed significantly increased cancer risk among the study populations despite their low-dose radiation exposure. These studies showed similar results even when the cumulative radiation dose was limited to an exposure group of less than 100 mGy, demonstrating that the observed excess risk was not affected by high exposure. A linear dose-response relationship between radiation exposure and cancer incidence has been observed, even at the low-dose interval. These recent epidemiological studies include relatively large populations, and findings are broadly consistent with previous studies on Japanese atomic bomb survivors. However, the health effects of low-dose radiation are assumed to be small compared to the risks that may arise from other lifestyle factors; therefore, the benefits of radiation use should be considered at the individual level through a balanced interpretation. Further low-dose radiation studies are essential to accurately determining the benefits and risks of radiation.

• Environmental Analysis Health and Toxicology
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• v.31
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• pp.1.1-1.13
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• 2016

Objectives To investigate the accuracy and scientific validity of the current very low risk factor for hereditary diseases in humans following exposures to ionizing radiation adopted by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection. The value is based on experiments on mice due to reportedly absent effects in the Japanese atomic bomb (A-bomb) survivors. Methods To review the published evidence for heritable effects after ionising radiation exposures particularly, but not restricted to, populations exposed to contamination from the Chernobyl accident and from atmospheric nuclear test fallout. To make a compilation of findings about early deaths, congenital malformations, Down's syndrome, cancer and other genetic effects observed in humans after the exposure of the parents. To also examine more closely the evidence from the Japanese A-bomb epidemiology and discuss its scientific validity. Results Nearly all types of hereditary defects were found at doses as low as one to 10 mSv. We discuss the clash between the current risk model and these observations on the basis of biological mechanism and assumptions about linear relationships between dose and effect in neonatal and foetal epidemiology. The evidence supports a dose response relationship which is non-linear and is either biphasic or supralinear (hogs-back) and largely either saturates or falls above 10 mSv. Conclusions We conclude that the current risk model for heritable effects of radiation is unsafe. The dose response relationship is non-linear with the greatest effects at the lowest doses. Using Chernobyl data we derive an excess relative risk for all malformations of 1.0 per 10 mSv cumulative dose. The safety of the Japanese A-bomb epidemiology is argued to be both scientifically and philosophically questionable owing to errors in the choice of control groups, omission of internal exposure effects and assumptions about linear dose response.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.3
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• pp.341-352
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• 2012

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to determine whether or not marked decreases in dry forage intake after 40 min of feeding are mainly caused by the two factors, that is, ruminal distension and increased plasma osmolality induced thirst produced by dry forage feeding. Six large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing $85.1{\pm}4.89kg$) were used in two experiments. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 am during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, saliva lost via the esophageal fistula was replenished by an intraruminal infusion of artificial parotid saliva (RIAPS) in sham feeding conditions (SFC) control, and the treatment was maintained under normal feeding conditions (NFC). In experiment 2, a RIAPS and non-insertion of a balloon (RIAPS-NB) control was conducted in the same manner as the SFC control of experiment 1. The intraruminal infusion of hypertonic solution and insertion of a balloon (RIHS-IB) treatment was carried out simultaneously to reproduce the effects of changing salt content and ruminal distension due to feed entering the rumen. The results of experiment 1 showed that due to the effects of multiple dry forage suppressing factors when feed boluses entered the rumen, eating rates in the NFC treatment decreased (p<0.05) after 40 min of feeding and cumulative dry forage intake for the 2 h feeding period reduced to 43.8% of the SFC control (p<0.01). The results of experiment 2 indicated that due to the two suppressing factors of ruminal distension and increased plasma osmolality induced thirst, eating rates in the RIHS-IB treatment were, as observed under NFC, reduced (p<0.05) and cumulative dry forage intake for the 2 h feeding period decreased to 34.0% of the RIAPS-NB control (p<0.01). The combined effects of ruminal distension and increased plasma osmolality accounted for 77.5% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality induced thirst are the main factors in the suppression of dry forage intake in large-type goats.