• Tuberculosis and Respiratory Diseases
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• v.60 no.1
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• pp.76-82
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• 2006

Background : The objective of this study was to understand sleep-related problems, and to determine whether the sleep questionnaires is a clinically useful method in patients who need polysomnography. Methods : Subjects were patients who performed polysomnography and who asked to answer a sleep questionnaires at the Sleep Disorders Clinic of St. Paul's Hospital, Catholic University of Korea. Baseline characteristics, past medical illness, behaviors during sleep-wake cycle, snoring, sleep-disordered breathing and symptoms of daytime sleepiness were analyzed to compare with data of polysomnography. Results : The study population included 1081 patients(849 men, 232 female), and their mean age was $44.2{\pm}12.8years$. Among these patients, 38.9% had an apnea-hypopnea index(AHI)<5, 27.9% had $5{\leq}AHI<20$, 13.2% had $20{\leq}AHI<40$, and 20.0% had $40{\leq}AHI$. The main problems for visiting our clinic were snoring(91.7%), sleep apnea(74.5%), excessive daytime sleepiness(8.0%), insomnia(4.3%), bruxism(1.1%) and attention deficit(0.5%). The mean value of frequency of interruptions of sleep was 1.6 and the most common reason was urination(46.3%). Epworth Sleepiness Scale(ESS) had a weak correlation with AHI(r=0.209, p<0.01). When we performed analysis of sleep questionnaires, there were significant differences in the mean values of AHI according to the severity of symptoms including snoring, daytime sleepiness, taking a nap and arousal state after wake(p<0.05). Conclusion : On the basis of statistical analysis of sleep questionnaires, the severity of subjective symptoms such as ESS, snoring, daytime sleepiness and arousal state after wake correlated with the AHI significantly. Therefore the sleep questionnaires can be useful instruments for prediction of the severity of sleep disorder, especially sleep-disordered breathing.

• 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 Environment and Ecology
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• v.29 no.4
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• pp.570-579
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• 2015

Lindera sericea, which belongs to genus Lindera in the Lauraceae family, is labeled under Least Concerned (LC) among Korean rare plants, floristics specific species IV grade and also flagpole species of the Mudeung National Park. It is distributed in Mt. Mudeung, Mt. Cheonbong and Mt. Chogye within gradients from $12^{\circ}$ to $51^{\circ}$. The slope area is from northeast to northwest sides and the altitude range of distribution site is between 220 m and 533 m. The vascular plants in the quadrate where Lindera sericea were studied were identified as a total of 72 taxa; 37 families, 54 genera, 66 species, 5 variants and 1 forma. Among the floristics specific species, IV grade species was Lindera sericea and III grade species were Stewartia pseudocamellia and Acer palmatum. Korean endemic species were Stewartia pseudocamellia and Carex okamotoi. As for the vegetation group, Quercus mongolica and Q. serratak - Lindera sericea, Styrax japonicus populations were found in Mt. Mudeung area where Lindera sericea appeared, Stewartia pseudocamellia-Lindera sericea and Sasa borealis populations were found in Mt. Cheonbong areas, Carpinus laxiflora - Lindera sericea and Sasa borealis populations were found in Mt. Chogye area, and Stewartia pseudocamellia-Lindera sericea and Sasa borealis populations were found in Songgwangsa area. A total number of 662 Lindera sericea individuals were examined. The number of trees with 1 trunk including younger individuals was 353 (53.32%), and the number of trees with 2 to 5 stems was 270 (40.79%). The number of trees with the greatest number of sprouts was 27. Of 662 trees in total, the total number of sprouts was 1,198. Among these, 699 trees (58.34%) were between 50 cm and 150 cm in height. The tallest tree was 585 cm. The most common root-collar diameter of sprouts (992, 82.81%) was under 1 cm, followed by the sprouts with collar diameter from 1.0 to 1.5 cm(156, 13.2%). Among them, the largest root-collar diameter was 3.2 cm. This Lindera sericea specimen had the tallest trunk (565 cm) which was torn lengthwise on one side. Its root and breast parts were decayed by 50% and 25 respectively. Some branches of the three trunks that were more than 4 m in length were dead in the apical portion. Therefore, it is proposed that the Korean Lindera sericea maintains an apical dominance tree type while showing morphological adaptation as a typical shrub because it autonomously decays some branches and trunks over a certain height while increasing the number of its sprouts.

• Journal of Life Science
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• v.20 no.3
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• pp.437-443
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• 2010

This study was designed to examine the aerobic capacity and ventilatory response during an incremental exercise in elite high school cyclists. Twelve boys ($17{\pm}1\;yr$, $175{\pm}5\;cm$, $70{\pm}9\;kg$) participated in anthropometric measurements, incremental exercise testing, and pulmonary function tests. During incremental exercise testing using a cycle ergometer, their maximal oxygen uptake ($VO_2max$), maximal power output, ventilation, ventilatory equivalents for oxygen ($V_E/VO_2$) and carbon dioxide ($V_E/VCO_2$), respiratory rate, and tidal volume were measured. Time variables such as inspiratory time (Ti), expiratory time (Te), breathing time (Tb), and inspiratory duty cycle (Ti/Tb), as well as inspiratory flow rate ($V_T$/Ti) were assessed. Pulmonary function of vital capacity (FVC), forced expiratory volume in one second ($FEV_1$), $FEV_1$/FVC, and peak expiratory flow were evaluated. Their $VO_2max$, maximal heart rate, and Wmax were $57.5{\pm}3.9\;ml{\cdot}kg^{-1}{\cdot}min^{-1}$, $194.1{\pm}8.6\;beat{\cdot}min^{-1}$, and 452 W, respectively. $VO_2max$ was not related to any anthropometric parameters. Most ventilatory variables progressively increased with exercise intensity. As intensity increased, Ti, Tb, Tb decreased while Ti/Tb was maintained. Below an intensity of 250 W, height, weight, body mass index, and body surface were highly correlated with $V_T$/Ti and Ti/Tb (p<0.05). Collectively, $VO_2max$ appeared to be lower than adult cyclists, suggesting a different pattern of ventilatory control as age advances. Morphological characteristics were not related to $VO_2max$ in the population. Time variables of ventilatory response seemed to be related only at an exercise intensity level of less than 250 W. $V_T$/Ti may be related to exercise endurance capacity, but Ti/Tb was similar to adult cyclists.

• The Korean Journal of Food And Nutrition
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• v.20 no.1
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• pp.53-62
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• 2007

In this study, physicochemical, microbiological and organoleptic analyses were carried out on cabbage kimchi, a representative fermented food, that was made with 0.5%, 1.0%, and 1.5% mulberry leaf powder during fermentation. This kimchi was then compared to, kimchi without added mulberry leaf powder. The pH values showed minimal differences between the two types of kimchi at the beginning of fermentation. The total acidities were low in every plot of kimchi and increased according to the fermentation. The total microbial cell and Lactobacilus counts increased rapidly in the exponential phase according to the fermentation, and showed little increase in the stational phase. Among the analyzed plots, the lowest population was found in the kimchi containing 1.0% of mulberry leaf powder. This kimchi, in particular, also had the best quality scores, overall acceptance and organoleptic test results during fermentation. Fermentation was slowed in the kimchi with mulberry leaf powder, according to the amount of added as compared to the kimchi without it also showed less acidity. The color appearance, however, of the kimchi with added mulberry leaf powder, was inferior to that of the kimchi without mulberry leaf powder.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.65-78
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• 2018

According to the in social aspects such as population growth, urbanization and industrialization, development of livestock industry by meat consumption, amount of organic wastes (containing sewage sludge and food waste, animal manure, etc) has been increased annually in South Korea. Precise monitoring of 11 organic wastes biogas facilities were conducted. The organic decomposition rate of organic wastewater was 68.2 % for food wastes, 66.8 % for animal manure and 46.2 % for sewage sludge and 58.8 % for total organic wastes. As a result of analyzing the biogas characteristics before and after the pretreatment, the total average of the whole facility was measured to be 560 ppm using iron salts and desulfurization, and decreased to 40 ppm when the reduction efficiency was above 90 %. Particularly, when iron salt is injected into the digester, the treatment efficiency is about 93 %, and the average is reduced to 150 ppm. In the case of dehumidification, the absolute humidity and the relative humidity were analyzed. The dew point temperature of the facility where the dehumidification facility was well maintained as $14^{\circ}C$, the absolute humidity was $12.6g/m^3$, and the relative humidity was 35 %. Therefore, it is necessary to compensate for the disadvantages of biogasification facilities of organic waste resources and optimize utilization of biogas and improve operation of facilities. This study was conducted to optimize biogas utilization of type of organic waste(containing sewage sludge and food waste, animal manure) through precision monitoring.

• The Korean Journal of Quaternary Research
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• v.19 no.1
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• pp.1-17
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• 2005

This study aims to study the distribution and formation age of Quaternary deposits in the downstream of Yeongsan Estuarine River, encompassing Muan, Illo and Donggang counties. For this purpose the authors examine several borehole data, and step trench survey for excellent profiles was studied in connection with grain size population and magnetic susceptibility. As a result, it is interpreted that the coastal plain of the Yeongsan River was formed by sea level rise after Last Glacial Maximum(LGM). The fore edge/escarpment of coastal terraces distributed 7-10 m asl is assumed to be formed during the last glacial period, while the coastal terraces distributed above 7-10m asl formed during MIS 5a. In addition, the fore edge/escarpment of coastal terraces distributed above 15 m asl is presumed to be have been formed during the stadial of last interglacial period, while the formation age of coastal terraces distributed above 15m(asl) is assumed to be MIS 5e. This formation age can be estimated by the coastal terrace ages of the southeastern coast of Korean Peninsula. The characteristics of Quaternary deposits linked to paleolithic culture will eventually lead to the reconstruction of ecosystem environment of paleolithic peoples.

• Journal of Distribution Science
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• v.10 no.5
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• pp.37-44
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• 2012

In this paper, we investigate several factors that affect the locational decision of discount stores by using previous studies on the marketing area and the location of commercial facilities. We selected 21 primary variables that are expected to influence the decision of store location and, by factor analysis, grouped them into five underlying factors. Among these, the demographic factor, which shows the potential purchasing power level, had the greatest impact on the locational decision for the store. However, we found individual stores positioned according to unique locational characteristics in addition to the demographic factor. It means that we have to additionally consider if the vicinity of the market is based on any physical properties. Many previous studies proposed four decision factors for store location: the economic factor, the demographic factor, the land utilization factor, and traffic factor. However, the fivefold factors-our distinctive contribution-are more concrete and persuasive according to Korean reality. We show that location preference is based on the following criteria: (1) the area is densely populated, (2) houses stand close together, (3) residents have a high income level, (4) road traffic is developed and easy to access, and (5) public transportation is well developed. The demographic factor has the greatest impact on the location of a discount store. The number of households has a greater relevance to the demographic factor than does the individual consumer. Second, discount stores relatively prefer places where houses are located close together because such places offer easy access to the market. Third, a place whose residents have a high income level will be preferred, with its large cars and excellent traffic conditions. Fourth, a location would be highly rated if the roads around commercial facilities are well developed and their accessibility is good. Finally, discount stores must be located close to bus stops because female consumers, including housewives-the most important customers-evaluate stores based on distance. In this research, the variable of consumer attitude and preference was excluded, and the location factors of discount stores were analyzed according to a microscopic view through physical spatial data. In the future, the opening of new discount stores based on the five factors indicated above will require a comparatively shorter time from the first project feasibility analysis. In addition, the result of our study can be applied to the field of public policy for constructing and attracting large-scale distribution facilities.

• Korean Journal of Health Education and Promotion
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• v.21 no.2
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• pp.17-32
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• 2004

The purpose of this study was to evaluate the patterns of stresses arising from various life styles and their related sociodemographic factors in urban residents. The subjects were recruited from the population of two ‘Dong’s (administrative blocks) representative of Daejeon city through stratified cluster random sampling during the period ranging from June I st to Aug. 31 st, 2003. Self-administered questionnaires, including items asking about subjects' sociodemographic characteristics, daily life styles, measurement of stresses by General Health Questionnaire (Goldberg, 1978), were delivered to 396 residents and their responses were analyzed with the following results. 1. Based on the discriminant scores of HPI, 46.7％ of the subjects were found to have less than 4 points (poor life style), whereas 53.3％ had points higher than 5 (good life style). Higher than 5 points were scored more frequently in females than in the male, in the age group of 40's - 60's than the 30's, in the group with spouse than without, in the group with both spouse and offsprings than without, and in the group owning a house than not. 2. Based on the degree of stress, 17.7％ of the subjects were determined to be healthy, 74.5％ were potentially under stress, and 7.8％ were at higher risk of stress. The proportion of healthy individuals were significantly higher in the male, advanced aged group(40's and 60's), the group with higher education years( over highschool), with higher monthly income over two million Won, and with spouse, than their respective counterparts. On the other hand the proportion of the individuals potentially under stress and at higher risk of stress was significantly higher in the female, in the age group of 30's and over 60's, in the group with academic career lower than middle school, with monthly income lower than two million Won, and without spouse. 3. Based on the relation of HPI with degree of stresses, subjects with HPI scores lower than 4 had increased rate of falling into the groups under potential stress and at higher risk of stress, while on the other hand those with over 5 points were found to be healthy in light of stress. 4. Based on the specific relation of each item of HPI with degree of stress, the proportion of healthy individuals was higher in the groups who take appropriate hours of sleep(7-8hours), who take breakfasts everyday, who take physical exercises everyday, who don't smoke, who don't drink alcohol, who take snacks everyday, who are overweight and obese, whereas the proportion of the group under potential stress and at higher risk of stress was higher in their comparable counterparts. 5. The relation of mean scores of HPI with stress scores in both male and female subjects showed negative correlation that the higher HPI scores, the lower stress scores. 6. Multivariate regression analysis to reveal the factors influencing the stress of the subjects showed that for men the significant factors were age, education, presence of job or not, exercise, subjective health status, with the explanatory power of 26.3％. For women, they included educational years, presence of spouse or not, job, owning a house or not, sleeping hours, drinking habit, taking snacks, subjective health status, with the explanatory power of 31.8％. The above study results suggests that stresses of urban residents have significant correlation with daily life styles and this correlation is also remarkably distinguished by different age and sex.

• Journal of Oral Medicine and Pain
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• v.31 no.4
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• pp.355-364
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• 2006

Headache is a common disease which influences not only individually but also socially. Temporomandibular disorders(TMD) refers to pain and dysfunction within the temporomandibular joint(TMJ) and associated muscles. TMD is presented commonly, and 70% of population are found to have one or more related symptom. A number of studies have been conducted to verify the association between headache and TMD, and some authors have proposed that headache and TMD may be related. In this study, we studied the patterns of headache presented by the patients who visited the TMJ and Orofacial pain clinic. Among the patients participated in this study, tension type headache showed the highest prevalence(48.5%), followed by migraine without aura(15.0%), probable migraine(10.6%), migraine with aura(7.1%), probable tension type headache(4.8%), and other primary headaches(1.8%). The high prevalence of tension type headache may be due to the accompaniment of orofacial pain by pericranial muscle tenderness. Comparison of sex showed that the rate of migraine was higher in female than male(female to male ratio 35.8:25.3). In age analysis, the rate of migraine was high in the twenties(42.2%) and the thirties(40.0%). As the age increased, the rate of migraine decreased, and this trend was in accordance with the previous studies. The percentage of the patients who had previously received treatment was only 26.2%, and that of those who were aware of the diagnosis was merely 8.7%. Therefore, it is not common for headache patients to get treatment, however, since orofacial pain is often accompanied by headache, more systematic diagnosis as well as precise treatment would be necessary. Moreover, since TMD could induce and aggravate headache, proper evaluation and management of TMD would be essential for diagnosis and treatment of headache. In the future, more systematic and broad investigation on the influence of causative factors of TMD on headache as well as the change in headache pattern with the treatment of TMD would be required.