• Reproductive and Developmental Biology
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• v.35 no.4
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• pp.435-439
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• 2011

Sildenafil citrate (SIL) a phosphodiesterase 5 inhibitor (PDE5I) has been used for long time as a first line oral drug for erectile dysfunction. Though it has beneficial effects on erectile organ it also has some adverse effects in other cells and/or tissues related to reproductive system when exposed to longer duration. The objective of the present study is to evaluate the long term effect of SIL on sperm parameters in Wistar albino rat. The animals are divided into two groups, for group I - rats were treated with saline (vehicle alone) and group - II oral administration of 5 mg/kg b.w. of SIL was administrated orally once in a day for 120 days. At the end of the trial period animals were sacrificed and epididymal sperm were subjected to various analysis. Results showed significant reduction in sperm count, motility, viability and morphologically intact sperm in long term PDE5I exposed animals when compared to control. Acrosomal status and fertility test also showed significant reduction in long term PDE5I exposed animals. The present study clearly indicated that long term SIL has shown to induce alteration in sperm quality and quantity, leading to decline in fertility rate. Indicate that SIL impinge on spermatogenesis as well as epididymal function. Understanding the molecular down-stream events involved in long-term exposure to PDE5 inhibitor can be valuable to supervise on related infertility issues and to suggest corrective measures.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.263-268
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• 2008

Estimates of genetic gain (in volume growth) and diversity (expressed as status number, $N_s$) were determined in a clonal seed orchard of Pinus koraiensis. The genetic thinning was based on clonal breeding values (represented by general combining ability) obtained from progeny tests, clonal fertility estimated by strobilus production, and clonal size variation determined by the ramet numbers per clone. Parental GCA values for volume growth were calculated, based on height and diameter at breast height measured from field trials. Clonal fertility was estimated from the assessments of strobilus production over twelve years from 1991 to 2003, and used for the calculation of status number. There are 179 clones and 5,268 ramets in 12ha area of P. koraiensis clonal seed orchard. Genetic gain and diversity estimates were determined under assumptions of 30% pollen contamination and inferior genetic value of contaminating pollen. Genetic gain increased as thinning rates were set from 10% to 60%. However, for the higher thinning intensities, the increase of genetic gain was not remarkable. Genetic thinning by means of truncation selection resulted in a greater genetic gain but a large decrease in status number. Status number was represented around 40 clones for 10% through 60% thinning intensities, but for the higher thinning intensities, it was a bit fluctuated. Based on the present results, it could be concluded that thinning rate should not be stronger than 60% to optimize genetic gain while conserving genetic diversity. Consequently 50% or 60% thinning rate might be appropriate for genetic thinning in the clonal seed orchard of P. koraiensis. The effect of pollen contamination on the genetic gain and the consequence of genetic thinning for seed production in the clonal seed orchard, and seed orchard management scheme were also discussed.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.143-149
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• 2018

This paper focuses on how Singapore has adopted the 'Marriage Promotion Policy' for resolving the low birthrate and how it has been using the Social Development Network (SDN) to cope with the problem of low fertility. Social Development Network is an organization that shows Singapore's national stewardship to marriage, and has developed from the beginning to the social phenomenon of increasing number of highly educated women and decreasing fertility. The predecessor of Social Development Network is 'Social Development Unit' (SDU), absorbed the 'Social Development Service' (SDS) that was launched later, and reborn as Social Development Network in 2009. At its inception, Social Development Network has been recruiting and organizing its own memberships without the help of commercial marriage agencies, and since 2006 has been dedicated to delegating dating and matchmaking services to private companies and supporting projects. The purpose of this paper using literature analysis is to analyze the status and role of Social Development Network from the theoretical point of view of marital stewardship to the present, and to suggest meaningful implications for Korea which has the same social experience.

• Reproductive and Developmental Biology
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• v.39 no.1
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• pp.7-11
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• 2015

Preservation of liquid semen is an important factor for breeding management in swine industry. Oxidative stress of spermatozoa during liquid preservation has a detrimental effect on sperm quality and decreases fertility. Objective of this study was to determine the effect of antioxidant, Quercetin, on capability of porcine liquid semen preservation. Freshly collected porcine semen from boars (n=3), having proven fertility was counted, diluted to $3{\times}10^7/mL$ and divided into 5 different semen extenders. Aliquots of diluted semen with different extenders were subjected to measure the pH, motility, viability and sperm DNA structure status on elapse time after preservation for 10 days. For the first 3 days, semen preserved in all 5 different extenders maintained their initial pH and either gradually decreased or increased thereafter, indicating lipid peroxidation has started. Sperm motility (r=0.52, p=0.01) and viability (r=0.55, p=0.03) had positive correlation with semen pH. Sperm motility was maintained well (p<0.05) in especially 2 extenders containing Tris and antioxidant compared to other extenders, suggesting both Tris and antioxidant worked as pH regulator and had beneficial effects on sperm characteristic during preservation. Sperm DNA structure status accessed by sperm chromatin structure assay on elapsed time after preservation, tended to be higher in semen preserved without antioxidant. Taken together, addition of antioxidant to extender prevents the sperm from oxidative stress during storage in mechanism by which antioxidant slows the lipid peroxidation, and thus reduced the reactive oxygen species in preserved porcine semen resulted in maintaining semen pH, sperm motility and viability for 7~10 days.

• Journal of the Korean Regional Science Association
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• v.40 no.3
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• pp.43-61
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• 2024

The purpose of this study is to identify the difference of regional characteristics affecting 'marriage stage' and 'childbirth stage' and to compare how these factors differ between metropolitan and non-metropolitan areas using a heckman two-stage selection model. The main findings are as follows. First, regional characteristics affecting marriage stage and childbirth stage are different. Second, in the metropolitan area, regional characteristics such as population density, the proportion of female employee, and housing prices have a relatively greater impact on 'marriage', and in the non-metropolitan area, regional characteristics such as population density and unemployment rate have more impact on 'childbirth'. The empirical analysis suggests that marriage and childbirth stage need to be distinguished when establishing low fertility policies, and these approaches should be differentiated at regional level.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.2
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• pp.94-100
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• 2020

The inverse correlation between maternal age and pregnancy rate represents a major challenge for reproductive endocrinology. The high embryo ploidy error rate in failed in vitro fertilization (IVF) cycles reflects genetic misfires accumulated by older oocytes over time. Despite the application of different follicular recruitment protocols during IVF, gonadotropin modifications are generally futile in addressing such damage. Even when additional oocytes are retrieved, quality is frequently poor. Older oocytes with serious cytoplasmic and/or chromosomal errors are often harvested from poorly perfused follicles, and ovarian vascularity and follicular oxygenation impact embryonic chromosomal competency. Because stimulation regimens exert their effects briefly and immediately before ovulation, gonadotropins alone are an ineffective antidote to long-term hypoxic pathology. In contrast, the tissue repair properties (and particularly the angiogenic effects) of platelet-rich plasma (PRP) are well known, with applications in other clinical contexts. Injection of conventional PRP and/or its components (e.g., isolated platelet-derived growth factors as a cell-free substrate) into ovarian tissue prior to IVF has been reported to improve reproductive outcomes. Any derivative neovascularity may modulate oocyte competence by increasing cellular oxygenation and/or lowering concentrations of intraovarian reactive oxygen species. We propose a mechanism to support intrastromal angiogenesis, improved follicular perfusion, and, crucially, embryo ploidy rescue. This last effect may be explained by mRNA upregulation coordinated by PRP-associated molecular signaling, as in other tissue systems. Additionally, we outline an intraovarian injection technique for platelet-derived growth factors and present this method to help minimize reliance on donor oocytes and conventional hormone replacement therapy.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.2
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• pp.15-20
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• 2020

Due to urbanization and industrialization, the population of rural areas has sharply decreased, and the social phenomena of low fertility and aging have occurred due to many factors such as the spread of individualism and single-person households derived from urbanization and economic growth. In order to cope with the low birth rate and the aged society, the Korean government has invested 152.1 trillion won from 2006 to 2015 and to proceeded total 231 projects in 3 different areas including the low fertility(95 projects), the aged society(78 projects), and the growth momentum(58 projects). Among the social problems caused by the low birth rate and the aged society, there have been not enough studies on the closed schools which will result from the social phenomenon of decreases in the school age population. The purpose of this study is to analyze the current extent of utilizing closed schools in Korea, to derive some types based on the analysis, and to provide basic data on the use of closed schools in Korea in the future. The types of closed schools can be classified into education facilities, social welfare facilities, cultural facilities, public sports facilities, income growing facilities, and others. Based on the classification, the analyses of the characteristics of each type for the facilities are presented.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.3
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• pp.161-170
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• 1975

Status of agriculture in Jeju province were investigated to find out problems and solutions in view of weather, soils and crop productions. Two hundred harmful windy days per year force to build strong wind-break forest near to farm. Somewhat severe drought situation in croping could be completely avoided by good irrigation system using abundant underground water resources. Poor fertility of soils should be improved by using much compost, lime, fused phosphate, and high dose fertilizers. Optimum fertilizer level for each crop should be determined with special consideration on characteristics of volcanic ash soil.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.3
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• pp.203-212
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• 2008

Objective: During cryopreservation process, cold shock and cryo-injury affect the fertilizing capacity of the sperm by damaging cell membranes with loss of functional integrity. A longstanding concept for preventing the cryo-damage is to stabilize the plasma membrane by incorporating cholesterol. This study was to determine the effects of cholesterol in freezing media on the motility and functional integrity of human sperm after cryopreservation. Methods: Control group (non-cholesterol treated) and different concentrations of cholesterol-treated sperm (14 healthy males) were frozen and thawed. After freezing and thawing of sperm, the quality of sperm was evaluated by sperm analysis, acrosome reaction test and sperm chromatin structure assay. Results: When human sperm were incubated in sperm freezing medium (SFM) containing $0.5{\mu}g$ cholesterol and then freezing/thawing, the motility of sperm have significantly improved compared to those untreated cholesterol ($33.46{\pm}1.48%$ vs. $30.10{\pm}1.07%$, p<0.05). The rate of calcium ionophore-induced acrosome reactions in post-thawed sperm was significantly higher than that ($53.60{\pm}1.60%$ vs. $47.40{\pm}1.86%$, p<0.05) in SFM containing cholesterol. Sperm chromatin structure assay revealed that DNA damage to the sperm in the cholesterol-treated group was lower than that of non-treated group. Conclusion: These results suggest that increased cholesterol content of sperm plasma membrane by supplementation of cholesterol in SFM improves sperm motility, capacitation status, and DNA integrity. Therefore, addition of cholesterol into SFM could be a useful for protecting human sperm from cold shock and cryo-injury during cryopreservation.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.1-7
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• 2001

Total upland area for cultivating the vegetable crops in the Alpine soils of Northeastern South Korea has been extending its limit to meet the increasing demand of vegetable food in recent decades. About 70% of these alpine soils are located in over 7% of the slope and most of vegetable crops have been cultivated intensively without practicing the best management systems. Thus, soil erosion and continuous cropping system have degenerated the soil fertility and shown detrimental effects on water quality. We initiated an intensive and extensive investigation to characterize the fertility problems encountered in these uplands. Objectives of this paper were to characterize the fertility status in the Alpine soils cultivated with vegetable crops for many years and to provide the recommendations for adequate soil management measures including fertilization and erosion control. Soils in general have good drainage with textural classes of loam or sandy loam. Their topographical characteristics tended to lead them to shallow plow layers, and the steepness of the terrain created erosion hazard. Of the soils examined, about 11% of uplands over 30% gradient was found in need of an urgent reforestation. A high content of gravel and firm hardness of soil attributed to inhibit the utilization of farm machinery and plant-root development. The average soil pH 5.6 was slightly low relative to pH 5.70 of the national average. Organic matter content was high compared with 2.0% of national average, but decreased with the prolonged cultivation periods. Available $P_2O_5$ concentration was unusually high due to the consequence of over dose application with chemical and organic fertilizers. Exchangeable cations as Ca, Mg, and K were appeared to be decreased in these regions with prolonging the cultivation periods. There were no significant differences in cation exchange capacity (CEC) and electrical conductivity (EC) among locations. Heavy metal contents were mostly lower than the threshold of danger level designated by Soil Environment Conservation Law of South Korea. Results indicated that a proper countermeasure and the best management practice should be immediately implemented to conserve the top soil and fertility in the Alpine regions.