• Korea journal of population studies
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• v.30 no.3
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• pp.107-135
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• 2007

This paper uses a static Gamma count model, a traditional hurdle model and an endogenous switching Poisson model, respectively for determining married women's completed fertility rates in Korea. This paper analyzes the impact of household income, women's wage and education, and women's job market participation on the number of children of married women above age 40 and on the expected number of children of women aged below 40. The paper shows that a household income significantly increases the number of children for at least women aged above 40, however, this income effect is disappearing for younger generation. The empirical model suggests that women having a job tend to have fewer children for a group 39 years old and below and find that there is an endogeneity problem between child birth and labor force participation, too. The education level of married women gives a positive effect for giving a birth, itself, while it gives a negative impact on the number of children. Based on the empirical results, it concludes that Becker's Quantity-Quality theory works for Korea, too.

• Development and Reproduction
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• v.11 no.3
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• pp.263-272
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• 2007

Contrast to mouse where its in vitro maturation rates are high without specific supplements or presence of the cumulus cells, there are some species, such as porcine, where its in vitro oocyte maturation rates are still very low. This comparative study was conducted to investigate the role of malate dehydrogenase(Mor2) during oocyte maturation by RNAi in the mouse and porcine. The Mor2 double-stranded RNA(dsRNA) was prepared speciesspecifically and microinjected into the cytoplasm of denuded germinal vesicle(GV) oocytes. Oocytes were cultured for 48 h(porcine) and 16 h(mouse) in M199 with 10% porcine follicular fluid, pyruvate, p-FSH, EGF, cystein, and estradiol-$17{\beta}$. We measured changes in oocyte morphology, maturation rates and mRNA levels after Mor2 RNAi. We confirmed gene sequence-specific knock down of Mor2 mRNA in both species after Mor2 RNAi. In contrast to our previous finding that mMor2 RNAi resulted in GV arrest in the mouse, we found that pMor2 RNAi resulted in MI arrest in denuded porcine oocytes(58%), but developed to MII(84.4%) in COCs. To determine whether this difference between mouse and porcine RNAi is due to differences in culture media, we cultured mouse oocytes in the M199 media for 16 h after mMor2 RNAi. Mouse oocytes were developed to MII stage(62%) and there was no statistical difference compared to that of non-injected(76.8%) and buffer-injected(73.3%) control groups. Therefore, we concluded that the mouse and porcine oocytes are having different metabolic systems in relation to malate dehydrogenase for oocyte maturation. This could be a basis for differences in maturation rates in vitro in two species. Further scrutinized studies on the metabolic pathways would led us in finding better culture system to improve oocyte maturation rates in vitro, especially in more challenging species like the porcine.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.785-796
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• 2006

This study was designed to evaluate the changes in sperm motility, viability, HOST(hypo-osmotic swelling test), IVP(in vitro penetration), SCSA(sperm chromatin structure assay) during storage of liquid semen collected from boars with different farrowing rates using AI, and to find the relationship between boar fertility through AI and sperm diagnostic parameters during semen storage. The results of HOST were significantly decreased according to the increasing of in semen storage days and the results of IVP were significantly decreased at 3 days of semen storage (P<0.05). The %Red was significantly different among the >80%, 70󰠏80% and <70% farrowing rate group at semen storage day 6(P<0.05). The correlation coefficients between the %Red and farrowing rate were increased according to the semen storage. In conclusion, these results suggest that the sperm parameters evaluated in these studies may be useful indicators to predict the fertility of AI and evaluate the semen quality in boars.

• Animal Bioscience
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• v.34 no.12
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• pp.1879-1885
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• 2021

Objective: Owing to the lack of a breeding index for efficient and quick fertility evaluations of Holstein bulls when using traditional or genome-wide detection methods, this study aimed to determine whether in vitro fertilization (IVF) could be used as an indicator of conception rate of artificial insemination (AI). Methods: Conventional and sexed frozen semen from nine bulls were used for IVF and AI. Results: The IVF and AI conception rates of each bull were confirmed to be positively correlated between the conventional frozen and sexed frozen semen. The correlation coefficient R values of nine bulls between IVF and AI methods were 0.73 and 0.97 for the conventional frozen and sexed frozen semen, respectively. The average conception rate of three bulls undergoing AI was 69.5% and 64.2%, 61.8% and 58.8%, and 48.2% and 46.2% in first-, second-, and third-born cows when conventional frozen and sexed frozen semen were used, respectively, which showed a positive correlation with the fertilization rate in the same parity. We propose an evaluation standard to assess the fertilization ability of bulls based on their IVF test results, which is categorized into three grades: grade one, normal fertility bull with an AI conception rate of 40%±5% and IVF rate of 45% to 60%; grade two, higher fertility bull with an AI conception rate of 50%±5% and IVF rate of 61% to 80%; and grade three, highest fertility bull with an AI conception rate of 60%±5% and IVF rate of >80%. Conclusion: These findings reveal that IVF results can be used as a breeding index for bulls to evaluate their AI conception ability, which may shorten the time required to select bulls for breeding.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.729-736
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• 2023

Traditionally, Germany, a conservative welfare state, has pursued a male breadwinner model based on gender division of labor. For a long time, Germany tried to address low fertility through economic support centered on cash benefits, but it was not successful. In 2007, the German government began to shift the paradigm of family policy for work-life balance under the slogan of "A mix of time policy, income transfer, and infrastructure." When the issue of low birth rates emerged as a national concern in Germany, there was a growing social sentiment that not only the government but also private companies should contribute to increasing fertility by providing family-friendly personnel policies and working conditions. Private companies have been voluntarily improving family-friendly working conditions beyond legal obligations, aiming to secure personnel and prevent turnover. Germany's fertility rate is currently rising toward the European average level in 2023, which can be attributed to the government's work-life balance policies and the participation of private companies. In terms of improving work-life balance policies in Korea, it has been proposed to change the perception of the need for fathers to participate in child care, to make parental leave compulsory for men, to guarantee employment for women after childbirth, to expand child care facilities, and to revitalize family-friendly policies in companies.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.103-110
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• 1993

This study was made to evaluate the chemical properties of 481 farmers' orchard fields in An-Seong area. And the reasonable ferilizer rates were recommended utilizing the result of soil analysis. The results are summarized as follows : 1. As the soil fertility status of collected soil samples were evaluated on the basis of temporary optimal range for each soil chemical properties, 12.7 to 49.6% of the total 481 farmers' fields were range for soil improvement. 2. The contents of chemical component have a tendancy to decrease with depth gradually from surface to subsoil. 3. According to the relationship between the contents of soil component in subsoil and those in surface soil, the fertility condition of subsoil could be estimated on the basis of analysis data of surface soil. 4. The multiple regression equation for pear yield prediction to the organic matter and exchangable calcium contents in the soil were obtained. 5. Referring the average value, distribution ratio compared to the optimum level for each soil chemical properties and standard fertilizer rate, the soil fertility status could be categorized as "High" "Medium" and "Low". For each category, the recommended amounts for NPK and organic matter application were established. 6. The recommended rates through soul fertility diagnosis were less than farmer's dosage in the range 7.1~7.7 kg/10a for N, 0.8~11.5 kg/10a for $P_2O_5$, 7.1~19.9 kg/10a for $K_2O$ and 90~116 kg/10a for lime.

• Korea journal of population studies
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• v.26 no.1
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• pp.31-57
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• 2003

This study is intended to examine (l)whether the value of son-for example, old age security and succession of family lineage- causing son preference in the traditional society can be explained at the individual level, (2)whether women without son in the son preference country continue her childbearing until having at least one son or give up the desire of having a son at a certain level. To accomplish these purposes, the 1974 Korean National Fertility Survey data are analyzed by the quadratic hazard models controlling unobserved heterogeneity. Unlike ordinary regression model, even omitted variables that affect hazard rates and are uncorrelated with the included independent variables can distort the parameter estimates in the hazard model. Therefore the nonparametric maximum likelihood estimator(NPMLE) of a mixing distribution developed by Heckman and Singer is used to control unobserved heterogeneity. Based on the statistical result in this study, the value of son causing son preference is determined at the societal level, not at the individual level. And Korean women without a son did not continue endlessly childbearing during child bearing ages until having a son. In general, they gave up the desire having a son when she had born six daughters continuously. Thus, 30-40 years ago, the number of daughters that women without a son giving up the desire of son was six, which is about the level of total fertility rate during 1960s. In these days, we can often see many women who have only two or three daughters and do not any son. This means that the level of giving up the desire of son, which is one factor representing the strength of son preference, becomes lower. If the strength of son preference did not become much weaker, then the fertility rates in Korea could not reach the below replacement level.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.2
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• pp.143-151
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• 2010

Objective: The aim of this study was to compare day 3 embryo transfer (D3ET) with day 5 ET (D5ET) in fresh in vitro fertilization (IVF) cycle on pregnancy outcomes. Methods: We conducted a retrospective matched case control study that included 90 women with D3ET and 90 women with D5ET from January 2007 to June 2009. Subjects were matched for reproductive profiles and IVF cycle characteristics. Two good quality embryos were transferred in both groups. Pregnancy rates (PR), implantation rate, and multiple PR were compared. Results: Demographics, stimulation parameters and embryological data were comparable in both groups. Main pregnancy outcomes with D3ET and D5ET groups were not statistically different: implantation rate (39.4% vs. 32.8%), positive PR (57.8% vs. 46.7%), clinical PR (53.3% vs. 45.6%), ongoing PR (50.0% vs. 42.2%), respectively. Both groups showed high multiple PR (37.5% vs. 34.1). Conclusion: D5ET may not be beneficial and necessary in comparison with D3ET on pregnancy outcomes, and elective single ET should be considered to decrease multiple pregnancies in women with favorable conditions and good quality embryos undergoing IVF.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.4
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• pp.349-359
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• 2010

Objective: This study was performed to compare the clinical outcome of elective single embryo transfer (eSET) performed at the cleavage stage to that of elective double embryo transfer (eDET). Methods: Of the women less than 36 years old who visited Daegu Maria from January 2008 to April 2009, the only women (n=330) with more than 8 mm of endometrial thickness and at least one good quality embryo, who were treated with GnRH agonist long protocol, were included in this study. After information about complications that can arise by multiple embryo transfer, either eSET or eDET was conducted by their request (167 and 163, respectively).Results: The implantation rate of eSET group was significantly higher than that of eDET group (53.9% vs. 40.2%, p<0.01). The twin pregnancy rate of eSET group was significantly lower than that of eDET group (1.1% vs. 32.3%, p<0.001). However, there were no significant differences between two groups in the clinical pregnancy (53.3% vs. 60.7%, p=0.172), ongoing pregnancy (47.3% vs. 54.6%, p=0.185) and live birth rates (44.9% vs. 50.9%, p=0.275). The number of the surplus embryos which developed to the blastocyst stage and cryopreserved at that stage was significantly higher in eSET group than that of eDET group ($3.2{\pm}2.6$ vs. $2.1{\pm}2.4$, p<0.001). Conclusion: These results suggest that eSET should reduce significantly the multiple baby pregnancy without decreasing the whole pregnancy rate in women with less than 36 years old.

• Clinical and Experimental Reproductive Medicine
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• v.18 no.1
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• pp.73-80
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• 1991

We compared fertilizing potential measurements by the zona-free hamster egg penetration assay with the in vitro fertilization and embryo transfer program was evaevulated for their ability to fertilize zona free hamster egg. Spermatozoa from 12 presumeably fertile donors and from the male partners of 56 infertile couples were evaluated for their ability to fertilizing potentials. Penertration rates of fertile donors were $36.2{\pm}27.7%$ ; Fertilization rates of infertile couples between with normal semen parameters and with abnormal semen parameters were $28.7{\pm}19.1$, $5.7{\pm}8.9%$, respectively. Sperm motility of couples with penetration rates between on 15-30% and on 30> were $54.1{\pm}4.6$, $55.5{\pm}8.3%$ respectively. Hamster penetration rates of couples participating in an in vitro fertilization and embryo transfer program was $38.9{\pm}29.9%$. But in one case, a positive fertility assessment was obtained in the absence of fertilization of the wife's eggs attributable to egg immaturity. This method may have potential value as a diagnostic tool in evaluation human sperm fertilization capacity which avoids the ethical and logistical problems associated with fertilizing of human eggs in vitro.