• Journal of Families and Better Life
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• v.33 no.4
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• pp.83-104
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• 2015

The purpose of this study is to provide diverse points of view to understand the low fertility issue of Korean society. For this phenomenological qualitative study, in-depth interviews were conducted with 14 married couples(28 persons) all raising three children. Participants were asked about overall family and work life, child care role performance, thoughts about child rearing, and their sociocultural context. Interview data were explored based on 6 analyzing steps offered by S, J, Talyor and R. Bogdan(1984). Most participants of this study were formed positive perceptions about having three children. Parents' positive perception was closely related with their attitude of not worrying too much about their children's future as well as child caring contexts around them. Parents' perception about having three children was also linked with their child care role construction process. In detail, parents with more positive perceptions tended to increase their level of child care involvement. This was particularly true for fathers. Mother and father's job situation emerged as an important factor to shape their child care involvement. In addition, child care attitude of people around them explained father's child care involvement. Applying these qualitative results, we first expect to provide detailed ideas about lives with three children in Korea. Second, based on our study findings, a more realistic and helpful policy to help the low fertility problem could be developed. Lastly, we also hope to provide helpful phenomenological qualitative research about low fertility issues of Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.962-967
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• 2010

The influences of the different mixture of urea fertilizer and pig manure compost as a nitrogen (N) source on Chinese cabbage yield, N uptake, and N agronomic efficiency (AE) were evaluated in two soils having different soil fertility levels. Increasing urea application level was very effective to improve yield and N uptake of Chinese cabbage, and the highest yield was obtained by urea fertilization alone in two soils. On the other hand, the lowest yield and N uptake was obtained from compost alone application in two soils. There was no significant difference in terms of the nitrogen AE between low and high fertility soils that were fully applied with urea. The AE values of Chinese cabbage applied by compost alone were significantly higher in the soil having a low fertility (28.8 g $g^{-1}$) than that in soil with high fertility (16.2 g $g^{-1}$), suggesting that N in compost was more responsive in improving the yield of Chinese cabbage in low fertility soils.

• Clinical and Experimental Pediatrics
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• v.54 no.11
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• pp.429-435
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• 2011

Although Korean population has been growing steadily during the past four decades, the nation is rapidly becoming an aging society because of its declining birth rate combined with an increasing life expectancy. In addition, Korea has one of the lowest fertility rates in the world due to fewer married couples, advanced maternal age, and falling birth rate. The prevalence of low birth weight infants and multiple births has been increased compared with the decrease in the birth rate. Moreover, the number of congenital anomalies is expected to increase due to the advanced maternal age. In addition, the number of interracial children is expected to increase due to the rise in the number of international marriages. However, the maternal education level is high, single-mother birth rate is low, and the gender imbalance has lessened. The number of overweight babies has been decreased, as more pregnant women are receiving adequate prenatal care. Compared to the Asian average birth weight, the average birth weight is the highest in Asia. Moreover, the rate of low birth weight infants is low, and infant mortality is similarly low across Asia. Using birth data from Statistics Korea and studies of birth outcomes in Korea and abroad, this study aimed to assess the changes in maternal and infant characteristics associated with birth outcomes during the past four decades and identify necessary information infrastructures to study countermeasures the decrease in birth rate and increase in low birth weight infants in Korea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.4
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• pp.345-352
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• 2011

Soil fertility different depend on application rate of manure and compost for many years. While each crop has different adaptability depend on soil fertility, crop and species or varieties should be chosen depending on the adaptability and productivity. These experiments were carried out to compare the five winter cereal crops for whole crop silage on growth, yield and feed value as affected by soil organic content. The rate of increase on no. of spikes at high fertile soil compared with medium fertile soil was sequently high Samhan (Oat's variety) > Cheongwoo (Wheat) > Gogu (Rye) > Youngyang (Barley) > Shinyoung (Triticale). The rate of decrease at low fertile soil compared with medium fertile soil was sequently high Youngyang > Gogu > Cheongwoo > Shinyoung > Samhan. The triticale was lower variation of no. of spikes as affected by soil organic content than that of other winter cereals. The variations of dry matter yield as affected by soil fertility was higher oat and barley and lower triticale. Forage yield of triticale was higher about 69 percent than that of barley at low fertile soil. Forage yield was the highest in triticale and the lowest in rye in all soil fertility. In high fertile soil, rate of increasing digestible dry matter (DDM) yield compared with medium fertile was high in Samhan and Youngyang. Rate of reduced DDM yield in low fertile soil compared with medium fertile was low in Shinyoung and Cheongwoo.

• Korea journal of population studies
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• v.30 no.2
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• pp.97-116
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• 2007

As the fertility level in Korea continues to drop with detrimental implications for the society, it has regained much attention of academics and policy makers. This study, building on the previous research on fertility behavior, attempts to explore the plan of young married women to have an additional child. While such plan is not always put into practice, it is still closely related to fertility behavior. In addition, it can provide useful clues to understanding behavior in the future. Utilizing a recent nationwide survey on marriage and fertility, the study analyzes the plan of further birth among young married women according to the number of their children. The results show that the plan for first child is quite universal as no difference is found by their socioeconomic and demographic characteristics. However, having plan for second child differs by the work status of husbands, presence of mother of young married women, and the sex of first child. The effects of first two factors suggest that young married women take into consideration stability of home economics and availability of care sharing. As for the plan for the child, the present and ideal sex composition of children appear most important. The results indicate that the mechanism of fertility progression differs by the current number of children. Thus, consideration of such differential would help us deepen our understanding of fertility behaviors and need to reflect in the study. The study also argues that comprehensive and systematic qualitative research should be accompanied by to capture complexity of fertility decision making process.

• Clinical and Experimental Reproductive Medicine
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• v.46 no.4
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• pp.173-177
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• 2019

Objective: We investigated the clinical characteristics of men with testosterone replacement therapy (TRT)-induced hypogonadism and its effect on assisted reproductive technology (ART) in infertile couples. Methods: This study examined the records of 20 consecutive male patients diagnosed with azoospermia or severe oligozoospermia (< 5 × 10⁶/mL) who visited a single infertility center from January 2008 to July 2018. All patients were treated at a primary clinic for erectile dysfunction or androgen deficiency symptoms combined with low serum testosterone. All men received a phosphodiesterase 5 inhibitor and TRT with testosterone undecanoate (Nebido^®) or testosterone enanthate (Jenasteron^®). Patients older than 50 years or with a chronic medical disease such as diabetes were excluded. Results: The mean age of patients was 37 years and the mean duration of infertility was 16.3 ± 11.6 months. At the initial presentation, eight patients had azoospermia, nine had cryptozoospermia, and three had severe oligozoospermia. Serum follicle-stimulating hormone levels were below 1.0 mIU/mL in most patients. Three ongoing ART programs with female factor infertility were cancelled due to male spermatogenic dysfunction; two of these men had normal semen parameters in the previous cycle. After withholding TRT, serum hormone levels and sperm concentrations returned to normal range after a median duration of 8 months. Conclusion: TRT with high-dose testosterone can cause spermatogenic dysfunction due to suppression of the hypothalamic-pituitary-testicular axis, with adverse effects on infertility treatment programs. TRT is therefore contraindicated for infertile couples attempting to conceive, and the patient's desire for fertility must be considered before initiation of TRT in a hypogonadal man.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.3
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• pp.148-152
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• 2011

Objective: Laser-assisted intracytoplasmic sperm injection (LA-ICSI), also known as micro-opening or thinning of the zona pellucida (ZP) prior to ICSI, may help to reduce mechanical damage to the oocyte during the procedure. The aim of the present study was to evaluate and analyze the efficacy of our institutional LA-ICSI program, which features laser-assisted ZP thinning prior to ICSI, in comparison with conventional ICSI (C-ICSI), performed on patients with different clinical characteristics. Methods: Patients undergoing a total of 212 ICSI cycles were randomly divided into an LA-ICSI group (106 cycles) and a conventional ICSI group (106 cycles). To reduce tissue damage, we thinned the ZP by approximately 70%, using a laser, before ICSI. Patients thus treated formed the LAICSI group. Comparisons included the morphological quality of transferred embryos, blastocyst development of the remaining embryos, and clinical pregnancy, in terms of ICSI method and patient characteristics. Results: Fertilization, development of remaining embryos, and pregnancy rate were significantly higher in the LA-ICSI group compared with the C-ICSI group. Fertilization, embryonic development, and the pregnancy rate were all improved in younger patients (<38 years of age) and in those who underwent a low number of IVF-ET attempts (<3 trials). In addition, the pregnancy rate was increased in older patients. Conclusion: LA-ICSI may be useful in improving the chance of pregnancy in all ICSI patients.

• The Korean Journal of Applied Statistics
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• v.33 no.4
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• pp.421-437
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• 2020

This paper implemented a method to predict the fertility rate, mortality rate, and international migration rate using the R program, which has been widely used in recent years, that calculates population projection by substituting the results into the Leslie matrix. In particular, the generalization log gamma model for the fertility rate by Kaneko (2003), LC-ER model for mortality rate by Li et al. (2013), and functional data model for international migration rates proposed by Ramsay and Silverman (2005) and Hyndman and Booth (2008), Hyndman et al. (2013) can be directly demonstrated with R programs. Demography and bayesPop have been introduced as a representative demographic package implemented in R; however, it can be analyzed only for data uploaded to Human Mortality Database (HMD) and Human Fertility Database (HFD) with data changes and modifications requiring application of other data. In particular, in Korea, there is a limitation in applying this package because it is provided only for short-term data in HMD. This paper introduces an R program that can reflect this situation and the different patterns of low fertility, aging, migration of domestic and foreigners in Korea, and derives a population projection for the year 2117.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.45-52
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• 1996

This study was conducted to know how cold tolerance of rice is inherited. Several crosses were made between cold tolerant and susceptible varieties, and their progenies were evaluated for days to heading, spikelet number per panicle and spikelet fertility under both cold water and natural conditions. In F$_1$ and F$_2$ generations, earlier heading, more number of spikelet per panicle and higher spikelet fertility under the cold condition were dominance, and less delay or reduction in heading days and spikelets per panicle by cold treatment were over dominance or partial dominance, while less reduction in spikelet fertility by cold-water irrigation was complete dominance. Heritability in most characters by cold treatment was high and there was less difference of heritabilities in heading days and spikelets per panicle between cold treatment and natural conditions, while there was much difference of heritability in spikelet fertility between two conditions. Heterosis in spikelet fertility was considerably high, while those in heading days and spikelets per panicle were relatively low. Heterosis in remote crosses was especially larger under the cold-water treatment condition compare with that under natural condition.

• Journal of Family Resource Management and Policy Review
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• v.12 no.2
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• pp.15-30
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• 2008

According to the research taken by the National Statistical Office, the fertility rate of a Korean fertile female is 1.17. This figure is the lowest in the world, and the reduction in the fertility rate over the last 30 years was the biggest in the world. It can be seen as a warning alarm about the effects of a low birth rate and a silver society. Assuming that there are several factors involved in this phenomenon, this study inquired into the attitude towards children, attitude towards nourishing children, attitude towards sex roles and the harmony between the jobs and families of married females, and examined the factors that influence the willingness to give birth. Final 581 copies of the survey questionnaire were used for analysis and the collected data were analysed by SPSS, Pearson's correlation analysis, t-test, ANOVA, and Duncan's Multiple Range Test. Three main conclusions were reached: Firstly, the value variables, such as sex-role attitudes and the preference for work or home, affect the willingness to give birth. Therefore, it can be said that one's values have a significant effect on these variables and the willingness to give birth. Secondly, both working morns and housewives have a strong tendency to give a birth if they are supported on child rearing. Finally, the employment of the married women itself can be a variable that can affect childbirth. In other words, the working hours affect employed married women so as sex-role attitudes, the preference between work and home, ideal number of children, and the income to housewives. Also, even in whole married women, the employment itself can be a major factor of the willingness to have a baby. Therefore, unemployed married women have more of a tendency to have children than employed married women.