• Journal of Families and Better Life
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• v.31 no.3
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• pp.141-151
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• 2013

The purpose of this study is to test the economic rationality hypothesis of the low fertility trap among 412 college students at 13 private universities located in Seoul. The respondents were requested to complete the self-administered questionnaire, and the hierarchical multiple regression analyses were performed for analyzing the data. The major findings of this study were as follows: First, the students' views on the prospects for their future employability were 54.6% for big business, 64.51% for medium-sized business, and 49.63% for public sector. In the most employable job, the mean desired monthly salary was 3,505,400 won, while the mean expected monthly salary 2,753,600 won. Second, hierarchical regression analyses revealed that the family income in parental home was positively related to youths' consumption aspirations. Finally, the gap between youths' consumption aspirations and their expected income was negatively related to their desired number of children, while not significantly related to their planned age of first child birth. Thus, the low fertility trap hypothesis was supported in terms of birth rate drop, but not supported in terms of childbearing postponement. The implications of the study results are discussed.

• Journal of Families and Better Life
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• v.23 no.2 s.74
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• pp.159-166
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• 2005

The purpose of this study was to understand the relationship between fertility rate and the women's employment experience in household having one child, to observe the effects of related personal factor, family factor and social factor. The sample population included 276 married women in the reproductive ages(25$\~$45 years old) which are no additional pregnant or delivery after the first child birth. The major findings of the research are as follows: First, it shows some relevance between the plan of child birth and the experience of women for employment. Specially, the married women experiencing discontinuance of employment become to have a plan and motivation about the second child birth. Second, the motivations of child birth in woman of lower fertility household are related to her age, the existence of young child, and the education. Thirdly, as a result of Logit analysis, they have the plan to deliver additionally after first child birth in case of younger age and higher educational achievement than Master degree.

• Human Ecology Research
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• v.53 no.1
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• pp.49-66
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• 2015

This study analyzes the effects of women's labour force participation and work-family reconciliation support on life-cycle fertility in Korea. The analysis is based on the longitudinal data from Korean Labour and Income Panel Study (KLIPS), which include the available information on life-cycle fertility and employment history. Employing a dynamic model of fertility, we estimated the life-cycle fertility of all the 15-49 years old women considered in this study by using a duration model. The major results of this study were as follows: First, women's labour force participation had a negative effect on the first birth, second birth, and all births (transition to births starting at different parities). Women's employment tended to lengthen the interval between births. Second, the availability of maternal leave had a positive effect on the first birth and all births for working women. Providing maternal leave to working women decreased the opportunity cost of childbearing and in turn, reduced the interbirth interval of women. However, the availability of parental leave had no significant effect on the births of working women. Third, the financial support for childcare had a positive effect on the first birth and all births. The economic support for childcare led to the reduction in the interbirth interval of women by increasing the probability of births. The use of a childcare center for the first child, which substitutes for the time that women needed to take care of their children, classified as time-intensive consumption goods, did not have any effect on the second birth. Fourth, the part-time employment of women had a positive effect on the second birth. A flexible working time schedule tended to decrease the interval between the first and the second births.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.1
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• pp.22-29
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• 2019

Objective: As paternal age increases, the quality of sperm decreases due to increased DNA fragmentation and aneuploidy. Higher levels of structural chromosomal aberrations in the gametes ultimately decrease both the morphologic quality of embryos and the pregnancy rate. In this study, we investigated whether paternal age affected the euploidy rate. Methods: This study was performed using the medical records of patients who underwent in vitro fertilization (IVF) procedures with preimplantation genetic screening (PGS) from January 2016 to August 2017 at a single center. Based on their morphological grade, embryos were categorized as good- or poor-quality blastocysts. The effects of paternal age were elucidated by adjusting for maternal age. Results: Among the 571 total blastocysts, 219 euploid blastocysts were analyzed by PGS (38.4%). When the study population was divided into four groups according to both maternal and paternal age, significant differences were only noted between groups that differed by maternal age (group 1 vs. 3, p= 0.031; group 2 vs. 4, p= 0.027). Further analysis revealed no significant differences in the euploidy rate among the groups according to the morphological grade of the embryos. Conclusion: Paternal age did not have a significant impact on euploidy rates when PGS was performed. An additional study with a larger sample size is needed to clarify the effects of advanced paternal age on IVF outcomes.

• Korean Journal of Pharmacognosy
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• v.2 no.1
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• pp.29-34
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• 1971

A comparative study on Angelica and Cnidium, the two genera of Umbelliferae growing in Korea, was carried about the cytology and fertility of pollen. The somatic chromosome number of Umbelliferae was found almost to be 2N=22. Both species of Kang-whal and Chun-gung were found to be in polyploid with different chromosome numbers each other. The pollen fertility among the species of Angelica was high, but Toh-chun-gung was zero percent. The species of Angelica have been generated with pollen fertility, but species of Cnidium with only root or rootlet.

• Korea journal of population studies
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• v.28 no.2
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• pp.183-203
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• 2005

Over the past four decades reproductive behavior has changed rapidly in much of the developing countries. The average total fertility rate has fallen by half from six or more to near three today. Between 1960 and 2000 the largest fertility decline occurred in Asia and Latin America. The mortality rate has decreased in most developing countries. The purpose of this study is to review the pattern of demographic transition in developing countries. At first, this study focuses on the regional fertility transition. In Africa, the total fertility rate has decreased from 6.59 to 4.85 between 1960 and 2000. However, the rate has rapidly fallen from 5.76 to 2.34 in East Asia. The same pattern is found in Latin America. The mortality rate has also decreased in most of developing countries. It is also interesting to find that there is a clear difference among developing countries. In terms of crude death rate, Latin American countries show the lowest rate, while African countries remain still high rate. The study also shows the relationship between socioeconomic indicators and fertility/mortality in developing countries. The result supports the hypothesized relationship between education and fertility. However, the effects of urbanization and income on fertility do not show consistent result. About mortality rate, however, the study shows the significant relationship between urbanization and infant mortality rate, between income and mortality. The study finally emphasizes that we should include 'AIDS' in the study of mortality in African countries.

• Development and Reproduction
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• v.20 no.3
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• pp.219-225
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• 2016

Most of the commercial devices for vitrification are directly immersed into the warming solution (WS) for increasing of warming rate. However, the previous modified cut standard straw (MCS) which has reported is difficult to immerse into the WS. The aim of this study was to investigate whether the long cut straw (LCS) could be useful as a stable tool for vitrified-warmed human blastocysts. A total of 138 vitrified-warmed cycles were performed between November 2013 and November 2014 (exclusion criteria: women ${\geq}38$ years old, poor responder, surgical retrieval sperm, and severe male factor). The artificial shrinkage was conducted using 29-gauge needles. Ethylene glycol and dimethyl sulfoxide (7.5% and 15% (v/v)) were used as cryoprotectants. Freezing and warming were conducted using the LCS tool. The cap of LCS was removed using the forceps in the liquid nitrogen ($LN_2$) and then directly immersed into the first WS for 1 min at $37^{\circ}C$ (1 M sucrose). Only re-expanded blastocysts were transferred after it was cultured in sequential media for 18-20 h. A total of 294 blastocysts were warmed, and all were recovered (100%). Two hundred eighty-five embryos were survived (96.9%). The vitrified-warmed blastocysts of all patients were transferred without any cancellation. We were able to achieve a reasonable implantation (24.2%), following by clinical pregnancy (36.2%), which then continued to ongoing pregnancy (36.2%), and live birth (31.2%). Using LCS is achieved the acceptable rates of survival, pregnancy and live birth. Therefore, the LCS could be considered as a stable and simple tool for human embryo vitrificaton.

• Korea journal of population studies
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• v.30 no.3
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• pp.137-156
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• 2007

Total fertility rate (TFR) increased from the lowest 1.08 in 2005 to 1.13 in 2006, and a debate is made whether the increase is temporary or continuous as a result of various pro-natal policies. This study intends to explore policy implications revealed in recent fertility change using vital statistics. For this purpose, tempo-adjusted fertility rate by birth order, fertility rate by age of mother and birth order, age-specific fertility for married, and age-specific divorce rate for married are analyzed. The increase of TFR and births for 2006 is largely due to increase of first births at early thirties with slowdown of delayed first marriage and first child birth. The increase of female population (the third wave effect of baby boom) and first marriages of late twenties in 2006 and 2007 would lead to increase of fertility during 2007-2008. But further increase is uncertain because of the decrease trend of marital fertility and increase trend of never-married for twenties. TFRs for first and second births reduced rapidly, while TFRs for third and above births showed no changes, and second births were largely affected by tempo adjustment of fertility. Thus, constructing social environment for first and second births is more effective and necessary than encouraging third births. In addition, social responsibility of child care, child-women health issues due to delayed births, and the need for multi-cultural family support system are discussed.

• Journal of Genetic Medicine
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• v.2 no.2
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• pp.79-81
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• 1998

Genetic amniocenteses were performed in a series of 127 patients as a routine study. Samples from the patients were cultured by in situ method, flask method or both according to the state of amniotic fluid. The overall success rate of culture was 97.6% and no culture failure was observed in the flask method. It took 5 days first of all and 8.15 days average from set-up to harvest and there were 7.2 colonies per dish in in situ method. Therefore, it is suggested that in situ method which decreased the mean culture days and made clonal analyses possible, is a clinically available and even more reliable method in parallel with flask method in prenatal diagnosis.

• Toxicological Research
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• v.18 no.2
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• pp.167-174
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• 2002

Historical control data have been shown to be valuable in the proper interpretation and validation of reproductive toxicology studies. The present data were compiled from rat fertility and early embryonic development studies conducted at Korea Institute of Toxicology during the 1994∼2001 period. These data were assembled in order to provide background information for the general and reproductive data collected in 11 fertility and early embryonic development studies using Sprague-Dawley rats obtain-ing from the Breeding Facility, Korea Institute of Toxicology, Korea. A total of 274 males and 274 females were used in these studies during the eight-year period. Parameters of fertility and early embryonic development included clinical sign, body weights, food consumption, organ weights, estrus cycle, copulation index, precoital time, fertility index, pregnancy index, sperm parameters, and early embryonic development parameters. Most of the values were comparable to the previous historical control data reported by other investigators. These data can be wed not only as a historical data base for the meaningful interpretation of data from reproductive and developmental toxicity studies, but also as a contribution to biological characterization of Sprague-Dawley rats.