• KDI Journal of Economic Policy
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• v.31 no.1
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• pp.105-138
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• 2009

Although the decline in fertility rate is generally observed along the history of economic development throughout the world, the continuing decline hitting below the replacement level in Korea over the recent years gathered serious social concerns on the ground that it accelerates the process of population aging. The total fertility rate in Koreareached 2.08 in 1983, and gradually fell to the levels of 1.08 in 2005 and 1.26 in 2007. The policy debate over the role of the government has been focused mainly on the level of theoretical discussion without substantial basis on firm empirical evidence and the determinants of fertility. The objective of the paper is to empirically investigate the fertility effect of the female wage, which is understood as one of the most important determinants of fertility in Koreasince 1980 focusing on one aspect of fertility, namely birth spacing. Using the Korean National Fertility Survey conducted in 2006, I estimate a duration model of first and second births taking into account individual heterogeneity, which turned out to be an important factor to control for. Compared with previous studies in the literature on the Korean fertility, the study has an advantage of using the complete pregnancy history of women in a more representative sample. Unlike the previous studies, the analysis also deals with the endogeneity of marriage by treating a certain age, rather than age at marriage, as the time in which a woman becomes exposed to the risk of pregnancy. The study shares the common problem in the literature on birth spacing of lacking relevant wage information for respondents in a retrospective survey. I estimate the wage series as a function of the basic characteristics using the annual Wage Structure Survey from 1980 to 2005, which is considered as a nationally representative sample for wage information of employees. The results suggest that the increase in female wage by 10 percent leads to a decrease in second birth hazard by 0.56~0.92 percentage points and that the increase in spouse's wage by the equal amount is accompanied by the increase in second birth hazard by 0.36~1.13 percentage points. These estimates are more precisely estimated and of smaller magnitude than those presented by the previous studies. The results are robust to the different specifications of the wage equation. The simulation analysis based on the predicted values shows that about 17% of the change in the second birth hazard over the period 1980 to 2005 was due to the change in the female wage. Although there is some limitation in data, the results can be viewed as one estimate of the role of female wage on the recent fertility decline in Korea. The question raised by the paper is not a normative one of whether a government should promote childbearing but a positive one thatexplains fertility decline. Therefore, if there is a wide consensus on promoting childbearing, the finding suggests that the policies designed to reduce the opportunity cost of women in the labor market would be effective. The recent movement of implementing a wide range of family-friendly policies including child care support, maternity leave, parental leave and tax benefit in developed countries should be understood in this context.

• Korean Journal of Plant Resources
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• v.31 no.2
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• pp.124-135
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• 2018

The study was performed to explore the molecular changes in the vegetative stage (3-and 5-leaf) of sorghum under waterlogging stress. A total of 74 differentially expressed protein spots were analyzed using LTQ-FT-ICR MS. Among them, 12 proteins were up-regulated and 3 proteins were down-regulated. Mass spectrometry (MS) results showed that about 50% of the proteins involved in various metabolic processes. The level of protein expression of malate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase related to carbohydrate metabolic process increased in both 3 and 5-leaf stage under waterlogging stress. These proteins are known to function as antistress agents against waterlogging stress. The expression of oxygen-evolving enhancer protein 1 protein related to photosynthesis was slightly increased in the treated group than in the control group, however the expression level was increased in the 5-leaf stage compared to the 3-leaf stage. Probable phospholipid hydroperoxide glutathione peroxidase protein and superoxide dismutase protein related to response to oxidative stress showed the highest expression level in 5-leaf stage treatment. This suggests that the production of reactive oxygen species by the waterlogging stress was the most abundant in the 5-leaf treatment group, and the expression of the antioxidant defense protein was increased.

• Journal of Life Science
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• v.19 no.8
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• pp.1104-1111
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• 2009

This study was conducted to evaluate the effect of Sikhe made by medicinal herb on the functional level of liver. Water extract I (12.9% W/W) and II (25.8% W/W) were obtained from medicinal materials: Caragana Sinica, Glycyrrhiza uralensis, Atractylodes rhizoma alba, Atractylodes rhizoma alba, Crataegus pinnatifida, Paeonia lactiflora Pasll., Hordeum vulgare Linne, Oryza sativa Linne, ginger, peer and jujube. Experimental groups were divided into the control diet group (C), high fat diet group (HF), high fat diet treated with 5% extract I group (HFE I ) and high fat diet treated with 5% extract II group (HFE II). In sensory evaluation, overall quality scores associated with color, aroma, flavor and taste were significantly higher in water extract II than in water extract 1. After investigating functional and lipid levels of livers in rats, we found that the administration of water extract I or water extract II to the high fat diet group (HF) did not affect the gain of body weight but mildly reduced GOT or GPT activity in the high diet group. Moreover, administration of these medicinal herbal extracts significantly decreased the levels of total lipid, triglyceride and total cholesterol in the high fat diet group (HF). However, administration of these medicinal herbal extracts did not affect the level of phospholipid. In conclusion, as Sikhe made by medicinal herb slightly decreased the activity of GOT or GPT and amount of lipid in liver, prevention against high fat diet is thought to be important for liver protection.

• Journal of Life Science
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• v.23 no.4
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• pp.501-509
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• 2013

Formaldehyde (FA) is widely used in industries, and it is an indoor and outdoor pollutant. Exposure to FA may cause inflammation and respiratory oxidative stress. Studies have demonstrated that FA can cause cancer in animal models. During the regeneration process of injured starfish (Asterina pectinifera), several changes have been observed in the expression of cytokines. In particular, higher TGF-${\beta}1$ expression has been detected in arm cut starfish extract after eight days. The current study was designed to elucidate the in-vitro and the in-vivo pharmacological effects of starfish extract on FA exposure. We investigated the protective effects of intact starfish extract and arm cut starfish extract on an IMR-90 cell line and on mouse lung injury in response to FA exposure. In the presence of FA, inhalation of the arm cut starfish extract was associated with more promising cell proliferation, TNF-${\alpha}$, NF-${\kappa}B$ decrement, and $I{\kappa}-B{\alpha}$ increment. In the experimental group, the pulmonary structure of the arm cut starfish extract-treated group in the presence of FA exposure was similar to the control group, whereas the FA exposure group showed damage to the pulmonary structure. Moreover, the arm cut starfish extracts was more effective than the intact starfish extracts in terms of the expression of TNF-${\alpha}$, NF-${\kappa}B$, $I{\kappa}-B{\alpha}$, and surfactant protein A. The results obtained in this study demonstrate that arm cut starfish extracts are more effective in protecting pulmonary structure and function against FA exposure than intact starfish extracts.

• Journal of Life Science
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• v.26 no.10
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• pp.1169-1181
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• 2016

The purpose of this study was to investigate the effects of the regular Upright Body Type Excercise on posture, muscle strength of leg, lung capacity and depression of people with mental illness. The subjects of this study were recruited from B mental health center (5 years and more mental illness patients, n=19) located in P city. For the exercise group, They were carried out the Upright Body Type Excercise Program during 8 weeks (60 min/time, 3 times/week). They were randomly divided into two groups. Exercise group (n=10) and Control group (n=9). And also, they were agreed with consent forms before the experiments. Research results were as follows. Through the upper body type exercise, there was significantly difference in PEF and FEV1/FVC in the trained group. And also, there was much improved in depression level in the trained group. The change of melancholy feeling before and after the program was not statistically significant. However, because of limitations of sampling size due to the peculiarities of the program participants, in consideration of the limit of statistical validation exists clearly, intended to better understand the subjective experience of attendees, qualitative analyzing(qualitative research) was carried out in parallel. It was conducted a deep interview only person accepted among program participants, thematic analysis, subject analysis tasks to be subdivided by classifying by considering the semantic units of what participants expressed, was thus carried out. It found that the degree of melancholy feeling of mental disorders who participated in the Upright Body Typed Exercise Program was reduced. The course of the experience of change in depression appered the three subjects and six sub-themes such as "the start of the change", "interest of the program", "recognition of the need of the body’s health", "physical health promotion", "recovery of physical function", "negative change of habits (attitude)", "reduction of sense of depression", "confidence that it is possible to", "hope for the future". Therefore, upper body type exercise is much helpful in lung capacity and mental health of people with mental illness. So, this type of exercise mostly needed in the people with mental illness group than the other group for the quality of life.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.8
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• pp.1182-1187
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• 2005

This study was designed to investigate the supplementary effects of Lentinus edodes which were harvested at different time period and part on acetylcholine content and its related enzyme activities in the brain of diabetic mouse model (KK mouse). We fed mice with standard diet (Control diet; CON) or 4 different kinds of experimental diets (DGC: on time harvested, cap of Dong Go; DGS: on time harvested, stipe of Dong Go; HSC: late harvested, cap of Hyang Sin: HSS: late harvested, stipe of Hyang Sin) to KK mouse for 8 weeks. Neurotransmitter such as acetylcholine contents, acetylcholinesterase activities, monoamine oxidase-B ac-tivities and lipid peroxide contents in the brain were measured. The results showed that acetylcholine content was significantly higher in DGC and HSC groups than CON group. The activities of acetylcholinesterase and monoamine oxidase-B enzyme were significantly inhibited in the brain of DGC and HSC groups compared with CON group. Lipid peroxide content was lower in DGC group than CON group. These results suggested that the cap of Lentinus edodes which were harvested on time and late time contain increased acetylcholine content and decreased acetylcholinesterase activities, monoamine oxidase-B activities and lipid peroxide contents. Thus the cap of Lentinus edodes which were harvested at different time periods may play an effective role in enhancing cognitive function.

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.448-468
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• 1996

To maintain its functional integrity, bone is continuously remodelled by a process involving resorption by osteoeclasts and formation by osteoblasts, In order to respond to changes in the physical environment or to trauma with the relevant action, this process is strictly regulated by locally synthesized or systemic fators, Prostaglandin $E_2(PGE_2$) is perhaps one of the best studied factors, having been known to affect bone cell function for several decades.$PGE_2$ has both anabolic and catabolic activities. Excess of $PGE_2$ has been implicated in a number of pathological states associated with bone loss in a number of chronic inflammatory conditions such as periodontal disease and rheumatoid arthritis. $PGE_2$ and other arachidonic acid metabolites have been shown to be potent stimulators of osteoclastic bone resorption in organ culture. The anabolic effects of $PGE_2$ were first noticed when an increase in periosteal woven bone formation was seen after the infusion of $PGE_2$ into infants in order to prevent closure of the ductus arteriosus. The cellular basis for the catabolic actions of $PGE_2$ has been well characterized. $PGE_2$increases osteoclast recruitment in bone marrow cell cultures. Also $PGE_2$ has a direct action on osteoclast serving to inhibit activity and can also indirectly activate osteoclast via other cells in the vicinity, presumably osteoblast. The cellular mechanisms for the anabolic actions of $PGE_2$ are not nearly so well understood. The purpose of this paper was to study the effects of $PGE_2$ and dibutyl(DB)cAMP on osteoblastic clone MC3T3El cells and on the generation of osteoclasts from their precursor cells. The effect of $PGE_2$ and DBcAMP on the induction of alkaline phoaphatase(AlP) was investigated in osteoblastic clone MC3T3El cells cultured in medium containing 0.4% fetal bovine serum. $PGE_2$ and DBcAMP stimulated ALP activity and MTT assay in the cells in a dose-dependent manner at concentrations of lO-SOOng/ml. Cycloheximide, protein synthesis inhibitor, inhibited the stimulative effect of $PGE_2$ and DBcAMP on ALP activity in the cells. $PGE_2$also increased the intracellular cAMP content in a dose-dependent fashion with a maximal effect at 500ng/ml. The effect of $PGE_2$ on the generation of osteoclasts was investigated in a coculture system of mouse bone marrow cells with primary osteoblastic cells cultured in media containing 10% fetal bovine serum.After cultures, staining for tartrate-resistant acid phosphatase(TRAP)-marker enzyme of osteoclast was performed. The TRAP(+) multinucleated cells(MNCs), which have 3 or more nuclei, were counted. More TRAP(+) MNCs were formed in coculture system than in control group. $PGE_2(10^{-5}10^{-6}M)$ stimulated the formation of osteoclast cells from mouse bone marrow cells in culture. $PGE_2(10^{-6}M)$ stimulated the formation of osteoclast cells from mouse bone marrow cells in coculture of osteoblastic clone MC3T3E1 cells This results suggest that $PGE_2$ stimulates the differentiation of osteoblasts and generation of osteoclast, and are involved in bone formation, as well as in bone resorption.

• Tuberculosis and Respiratory Diseases
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• v.51 no.6
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• pp.530-539
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• 2001

Background : Bronchial asthma is an inflammatory disease of the airways that is associated with airway remodeling. The vascular endothelial growth factor (VEGF) is a potent, multifunctional cytokine that contributes to angiogenesis and inflammation. Matrix metalloproteinase-9 (MMP-9) is a major proteolytic enzyme that in duces bronchial remodeling in asthma. However, there is no data available on the possible role of the VEGF or on the potential relationship between the VEGF and MMP-9 in acute asthma. Therefore, the VEGF was studied to determine whether or not it participates in airway inflammation during acute asthma. An additional aim of this study was to determine whether or not the VEGF levels correlated with the MMP-9 levels in the sputum of acute asthma patients. Methods: Both the VEGF and MMP-9 levels were measured by an enzyme immunoassay and zymographic analysis in the sputum of patients with either stable asthma or with acute asthma. The VEGF and MMP-9 levels were also evaluated during a spontaneous asthma attack. Results : The VEGF levels were significantly higher in the sputum of acute asthmatic patients than in either the stable patients the control subjects. The VEGF levels in the sputum during asthma exacerbation were significantly higher than those on the remission days, and those levels decreased after asthma therapy. In acute asthmatic patients, the VEGF levels in the sputum correlated with the number of neutrophils and eosinophils. In addition, a significant correlation was established between the VEGF and MMP-9 levels in the sputum. Conclusion : These results suggest that VEGF overproduction is associated with airway inflammation during acute asthma and is related to the MMP-9 function.

• Sleep Medicine and Psychophysiology
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• v.21 no.1
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• pp.5-13
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• 2014

Objectives: Depression, sleep complaints and cognitive impairments are commonly observed in the elderly. Elderly subjects with depressive symptoms have been found to show both poor cognitive performances and sleep disturbances. However, the relationship between sleep complaints and cognitive dysfunction in elderly depression is not clear. The aim of this study is to identify the association between sleep disturbances and cognitive decline in late-life depression. Methods: A total of 282 elderly people who underwent nocturnal polysomnography in a sleep laboratory were enrolled in the study. The Korean version of the Neuropsychological Assessment Battery developed by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD-K) was applied to evaluate cognitive function. Depressive symptoms were assessed with the geriatric depression scale (GDS) and subjective sleep quality was measured using the Pittsburg sleep quality index (PSQI). Results: The control group ($GDS{\leq}9$) when compared with mild ($10{\leq}GDS{\leq}16$) and severe ($17{\leq}GDS$) depression groups, had significantly different scores in the Trail making test part B (TMT-B), Benton visual retention test part A (BVRT-A), and Stroop color and word test (SCWT)(all tests p<0.05). The PSQI score, REM sleep duration, apnea-hypopnea index and oxygen desaturation index were significantly different across the three groups (all indices, p<0.05). A stepwise multiple regression model showed that educational level, age and GDS score were predictive for both TMT-B time (adjusted $R^2$=35.6%, p<0.001) and BVRT-A score (adjusted $R^2$=28.3%, p<0.001). SCWT score was predicted by educational level, age, apnea-hypopnea index (AHI) and GDS score (adjusted $R^2$=20.6%, p<0.001). Poor sleep quality and sleep structure alterations observed in depression did not have any significant effects on cognitive deterioration. Conclusion: Older adults with depressive symptoms showed mild sleep alterations and poor cognitive performances. However, we found no association between sleep disturbances (except sleep apnea) and cognitive difficulties in elderly subjects with depressive symptoms. It is possible that the impact of sleep disruptions on cognitive abilities was hindered by the confounding effect of age, education and depressive symptoms.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.153-164
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• 1999

The solubilization of BTEX was evaluated in aqueous surfactant solutions with and without several additives. Anionic surfactant(Sodium Dodecyl Sulfate, SDS) and nonionic surfactants (NEODOL(equation omitted)25-3 and $SOFTANOL\circledR-90$ were used as test surfactants. The effects of surfactant HLB(Hydrophile-Lipophile Balance) Number and hydrocarbon molar volume and polarity of BTEX on the MSR(Molar Solubilization Ratio), micelle-water partition coefficient of BTEX, and CMC(C,itical Micelle Concentration) were investigated. Optimizing treatment conditions applicable to enhanced solubilization was also studied by manupulating salinity or electrolyte control with additives of ethyl alcohol, hydrotrope, and electrolyte solution. The most effective surfactant for solubilization was found $SOFTANOL\circledR-90$, since HLB number of 13.6 is similar to those values of BTEX ranging between 11.4 and 12.2, which was also proved experimentally. Ethyl alchohol of 3% was the most effective additives in reducing CMC and improving solubilization among the conditions using SDS, NEODOL(equation omitted)25-3, and $SOFTANOL\circledR-90$ with three additives. The partitioning of BTEX between surfactant micelles and aqueous solutions was characterized by a mole fraction micelle-phase/aqueous phase partion coefficient, $K_m$. Values of log $K_m$. for BTEX compounds in surfactant solutions of this study range from 2.95 to 3.76(100mM SDS) and 2.95 to 3.49(117mM $SOFTANOL\circledR-90$. Log $K_m$ appears to be a linear function of log $K_{ow}$ for SDS and $SOFTANOL\circledR-90$. A knowledge of partitioning of BTEX in aqueous surfactant system can be a prerequisite for the understanding of the behavior of hydrophobic organic compounds in soil-water systems in which surfactants play a role in remediation of contaminated soil and facilitated transport.