• Korean Journal of Environment and Ecology
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• v.25 no.3
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• pp.358-364
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• 2011

To examine the possibility of natural regeneration of six Acer species in broadleaved mixed forest in Korean peninsula, samples of six Acer species' samaras were collected at several seed sources from September to October 2009 and 2010, and seed morphological characteristics and viability were studied using cutting method. Inflorescense type of Acer mandshuricum(AM), A. pseudosieboldianum(APS) and A. palmatum(AP) is corymb, that of A. pictum subsp. mono(APSM) and A. okamotoanum(AO) is flat-topped panicle, and that of A. ukurunduense(AU) is raceme. Number of seed-set per inflorescense proves the highest value 38.5 sets in AU and the lowest value 2.4 sets in APS. Diameter of the seeds proves highest value 13.5mm in AO, and the lowest value 4.7mm in APS. Angles between the wings proves the highest values $130.05^{\circ}$ in APS, and the lowest value $48.60^{\circ}$ in AU. Air dry weight of 20 seed-sets proves highest value 3,900mg, in AO, and the lowest value 404mg in AU. Viable seed ratio of AP proves 50%, and that of AU does 43.2%. Those of other four species ranges 8.6~22.2%. Considering postdispersal seed predators and disturbance of litter, viable seeds of APSM, AO, AM, and APS supplied in the natural forest in Korea might be insufficient for seedling establishment. This study showed that sound viable seed supply might be key factors of natural regeneration of major Acer species in Korea. The openings made by insect pests were observed on the seed-coat of APSM, AM, AU, and APS samara, and Bradybatus sharpi were observed in the samaras of APSM and AO. Further study on the seed insect fauna, pre- and post-dispersal seed viability, and annual variation on these factor should be needed.

• Korean Journal of Environment and Ecology
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• v.23 no.1
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• pp.41-49
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• 2009

This research conducted a survey on the feeding crane's size, formation and distribution distance subsequent to road pattern and feeding flock's size during the wintering season eight times at the Cheolwon basin in Korea from December 2005 until February 2006. The survey results are as follows: First, the feeding flocks of the Red-crowned and White-naped Crane were found to mainly consist of two to four individuals. Mono-specific feeding flocks were more identified than hetero-specific feeding flocks in both Red-crowned and White-naped Cranes. There existed a significant difference in the ratio by size between the feeding Red-crowned and White-naped Cranes. The crane's average distribution distance from the paved road was much farther than from the unpaved road, paved farm road and unpaved farm road. In case of the white-naped crane, there was a difference in its distance length from between the road and farm road and there existed a significant difference only in the paved road in the distance length by road pattern between these two bird species[Red-crowned and White-naped Crane]. Such a result indicates that crane species don't prefer the road with frequent vehicular traffic to the road with low vehicular traffic. 5 or more individuals of feeding flocks of the Red-crowned Crane were located at a farther distance length from the paved road comparing to less than 5 individuals of the whole feeding flocks and less than 5 individual feeding flocks. 5 or more individuals of feeding flocks of the White-naped Crane were located at a farther distance length from the paved road, paved farm road and unpaved farm road than less than 5 individuals of feeding flocks of the White-naped Crane; however, there existed no difference in distance length subsequent to their group size. Conclusively, it was found out that the flocks with a larger size were more greatly affected by interrupting factors. Considering such results, there seems to be a more relation to the fact that larger size feeding flocks of crane species have a higher efficiency in the lookout for their surroundings.

• Korean Journal of Environment and Ecology
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• v.23 no.5
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• pp.418-430
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• 2009

The main purpose of this study is to investigate the relationship between the topography of land and vegetation and the preferred habitat of wintering cranes. Investigations were conducted twelve times in Cheorwon basin, South Korea, during two wintering seasons (12/2005 - 2/2006; 1/2007 - 2/2007). The density of rice grain in the middle of rice paddies was higher than that of the areas along the edge of rice paddies. However it was observed that red-naped cranes preferred to feed along the edges of rice paddies rather than to feed in the middle of the paddies. White-naped cranes, on the other hand, Preferred to feed in the middle of paddies. To be more specific, red-crowned cranes preferred feeding sites such as levees of the paddies or the areas where the level of the rice beds was comparatively more elevated. But the preference of the white-naped cranes turned out to be just the opposite. Another finding was that both red-naped cranes and white-naped cranes preferred concealed areas for their feeding site, and the frequency rate of their feeding in concealed areas has little to do with weather factors. This finding contradicts a widely accepted view that cranes prefer open spaces for their feeding site. Besides, red-crowned cranes, compared with white-naped cranes, preferred to feed in more concealed areas. The frequency rate of feeding in both concealed areas and non-concealed areas had little to do with the size of feeding flocks. There was no difference between a flock of fewer than five cranes and a flock of more than five cranes in terms of frequency rate of their feeding. In conclusion, the result of these investigations indicate that red-naped cranes comparatively prefer concealed areas for their feeding site, and white-naped cranes are less prone to them, and there is no direct connection between their preference of feeding site or frequency and the size of their flock. This is presumed to be the characteristics unique to their individual species.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.76-84
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• 1999

Objectives: A number of studies have shown that sleep deprivation results in reduced vigilance and increased negative affects such as tension, depression and anger. However there are few studies about effects of sleep deprivation on anxiety. The purpose of this study was to investigate the effects of 40 hour sleep deprivation on state anxiety, affects, sleepiness and fatigue. The authors also intended to study the effect of trait-anxiety on these psychological variables after sleep deprivation. Methods: Twenty nine subjects(22 men, 7 women, $24.59{\pm}1.35$ years of age) participated in this study. Subjects had no past history of psychiatric disorders and physical illnesses, and had normal sleep-waking cycle without current sleep disturbances. All of the subjects completed sleep dairy for two weeks to exclude some who suffered from chronic sleep deprivation or sleep disturbances. Subjects were instructed to get a normal sleep as usual at night before the study. After awakening, subjects remained awake for 40 hours under continuous surveillance. They completed State-Trait Anxiety Inventory, Index of General Affect, Stanford Sleepiness Scale and Fatigue Questionnaire every three hours, therefore they completed the scales 14 times totally. Subjects were dictated not to take caffeine, alcohol, or any medications on the day of the study. Heavy exercises and naps were restricted too. Results: Sleep deprivation resulted in increased state anxiety, negative general affects, and increased sleepiness and fatigue(p<.001). Dividing into high trait-anxiety group and low trait-anxiety group, there was significant sleep deprivation x traitanxiety interaction effect on general affect(p<.05). But, there was no significant sleep deprivation x trait-anxiety interaction effect on state-anxiety, sleepiness and fatigue. During sleep deprivation, the highest ratings of scales on anxiety, negative affect, sleepiness and fatigue occurred between 4 : 00AM and 7 : 00AM. Conclusions: These results show that sleep deprivation results in increased anxiety, mood state disturbance and increment of sleepiness and fatigue. These findings also suggest that trait-anxiety is a factor that influences the degree of worsening in general affect caused by sleep deprivation. During sleep deprivation, the rating curves of anxiety, affect, sleepiness and fatigue show rhythmicity that may be related to circadian rhythm.

• Sleep Medicine and Psychophysiology
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• v.4 no.1
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• pp.66-76
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• 1997

Objectives : The purpose of this study is to analyse sleep habits and sleep disorders in the elderly population ased 65-84 years. Methods : Epidemiological survey was performed at home by means of semi structured interviews in the city of Pusan, Korea. Subjects were randomly selected. The questionnaire consisted of 128 items including demographic findings, sleep habits, sleep disorders, somatic illnesses, and psychological distresses. Results : (1) The mean retiring time was 10.28 h (SD 1.30 h) and the mean wake-up time was 5.24 h (SD 1.33 h). The mean duration of sleep was 5.63 h (SD 1.80 h). The mean sleep onset time was 44.51 min. The mean frequency of daytime napping was 2.49 (SD 3.23). The subjects reported they woke up an average of 2.05 (SD 1.59) times per night. All of the above results were not related to age or gender. However, the mean frequency of difficulty in initiating/maintaining sleep was 2.2 times for men and 3.2 times for women (p<0.05). (2) The prevalence of insomnia was 57.7% and was not related to age or gender. Difficulty in initiating sleep was the most commonly reported insomnia complaint(52.4%). Early morning awakening was reported by 50.0% of patients and difficulty in maintaining sleep was reported by 45.1% of them. Worrying in bed and physical pain were strong contributing factor to insomnia. Conclusions : The results of our study showed several characteristics of sleep habits in the elderly. Sleep disorder in old age is not inevitable or trivial. Since sleep disturbance in older adults is common and distressing, it has implications for general health and well-being. Active concern and therapeutic intervention for the sleep habits and sleep disorders in the elderly are needed.

• Sleep Medicine and Psychophysiology
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• v.11 no.1
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• pp.22-28
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• 2004

Objective: The purpose of this study is to investigate the prevalence rate of OSA in subjects whose main sleep complaint is insomnia and to find differential factors of OSA in these insomniac subjects. Method: We reviewed the medical records and polysomnographic findings of patients referred to the Sleep Laboratory at Seoul National University Hospital from January 1996 to December 2002. Four-hundred and seventy subjects complained of insomnia as their main sleep problem (235 males and 235 females, mean age $53.6{\pm}12.4\;years$). First, we investigated the prevalence rate of OSA in these insomniac patients. Second, we compared the clinical and demographic characteristics of the OSA-associated group with those of the non-associated group. Third, we examined whether the degree or presence of differential factors within the OSA group correlate with severity of OSA, as determined by the respiratory disturbance index (RDI). Results: Among 470 insomniac subjects, 125 subjects (26.6%) were diagnosed as OSA by nocturnal polysomnography. OSA-associated subjects were significantly older ($58.4{\pm}12.3\;years$ vs. $51.8{\pm}11.2\;years$, p<0.01), and had significantly higher body mass index (BMI) ($23.4{\pm}3.3\;kg/m^2$ vs. $22.5{\pm}3.1\;kg/m^2$, p=0.44) than non-associated subjects. The OSA-associated group had more subjects with male gender (64.0% vs. 44.9%, p<0.01), hypertension (20.0% vs. 9.3%, p<0.01) or snoring (96.0% vs. 63.5%, p<0.01). Within the OSA-associated group, age had a significant positive correlation with RDI (p=0.01). Conclusion: We found that a considerable portion of patients complaining of insomnia as their main sleep problem were diagnosed as OSA. Snoring, old age, male gender, obesity, and comorbid hypertension were found to be differential factors of OSA in insomniac patients. We suggest that diagnostic efforts including nocturnal polysomnography are needed for insomniac patients with any of the above risk factors of OSA.

• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.107-119
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• 1996

To understand vegetation changes along environmental gradients in the natural forests in the east side of the Cascade Range in Washington state, USA, line transects were used to sample six different forest environments in the Wenatchee National Forest in the north-facing and south-facing sites at 975, 1280 and 1700m elevation. Data were analyzed using ordination by detranded correspondence analysis. Pseudotsuga menziesii was found as one of the dominant species on all the six sites regardless of elevation or aspect, while Pinus ponderosa was dominant on south slopes only. Abies grandis and A. lasiocarpa were dominant species on north slopes at elevations of 1280 and 1700m, respectively. Moisture, as it related to aspect, was identified as one of the most important environmental gradients for explaining the variation of vegetation types. On north-facing slopes, compared to south-facing slopes, where moisture was not as limiting and canopies could grow denser, probably, elevation or competitive interaction was more important. Species diversity tended to decrease with increasing environmental severity, with south slopes having less diversity than north slopes due to extended water stress and harsher temperature extremes on south slopes. The age structure on north-facing and south-facing slopes was different. Light intensity, moisture and climate were different between these two slopes. Large scale disturbances(e.g., big fire or insects) were major causes in changing age structure. Younger trees showed a closer relationship between size and age than adult trees. DBH values of shade intolerant species in south-facing slope were bigger than those of north-facing slope, which suggested that aspect of stands be the most important factor for age and size.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.627-633
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• 2014

Annual biomass production and amount of organic carbon in Abies koreana forest at Mt. Halla were conducted as a part of Korea National Long-Term Ecological Research (KNLTER). We measured standing biomass change of litter, soil production and organic carbon amounts of the forest floor and soil layer of A. koreana forest in Mt. Halla from 2009 to 2013 in permanent plots. Standing biomass, which was determined by allometric method, was converted into $CO_2$. The standing biomass in A. koreana forest was 98.88, 106.42, 107.67, 108.31, $91.48ton\;ha^{-1}$ in 2009, 2010, 2011, 2012 and 2013 year, respectively. The amount of annual carbon allocated to above ground was 35.95, 38.69, 38.96, 39.46, $33.2ton\;C\;ha^{-1}$ and below ground biomass was 8.54, 9.2, 9.49, 9.28, $7.97ton\;C\;ha^{-1}$ in 2009, 2010, 2011, 2012 and 2013 year, respectively. Amount of organic carbon returned to the forest via litterfall was 1.09, 1.80, 1.32, 2.46 and $1.20ton\;C\;ha^{-1}$ in 2009, 2010, 2011, 2012 and 2013. Amount of organic carbon in annual litter layer on forest floor was 2.74, 2.43, 2.00 and $1.16ton\;C\;ha^{-1}$ in 2010, 2011, 2012 and 2013 year, respectively. Amount of organic carbon within 20cm soil depth was 55.77, 54.9, 50.69, 44.42 and $41.87ton\;C\;ha^{-1}20cm^{-1}$ in 2009, 2010, 2011, 2012 and 2013 year, respectively. Then standing biomass and organic carbon distribution increased steadily until 2012. But there declined in 2013 because of the typhoon Bolaven. Thus, standing biomass and organic carbon distribution of this subalpine forest were largely affected by natural disturbance factor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1395-1404
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• 2013

The purpose of this study was to evaluate the diet quality in Korean middle-aged women based on their self-rated health status (SRH) as well as to investigate the relationship between SRH and the diet quality. For the study, we obtained data for analysis from the combined 2008~2009 Korean National Health and Nutrition Examination Survey (KNHANES). The study subjects were divided into two groups-'Good' group (${\geq}3.06$, n=622) and 'Bad' group (<3.06, n=1,092)- on the basis of the average SRH value (3.06). The women in the 'Good' group had achieved a higher education level and had a significantly high monthly average income (P<0.05), whereas women in the 'Bad' group had a larger waist circumference (P<0.05). In addition, women in the 'Good' group engaged in more physical activities (P<0.01). In comparison with the women in 'Bad' group, women in the 'Good' group were found to have a superior nutritional status, with a nutrient adequacy ratio (NAR) of protein (P<0.05), calcium (P<0.05), iron (P<0.05), vitamin A (P<0.05), vitamin $B_2$ (P<0.05), and niacin (P<0.01). The mean adequacy ratio (MAR) of women in the 'Good' group was also significantly higher than that of the women in the 'Bad' group. The index of nutritional quality (INQ) of protein (P<0.05), iron (P<0.05), vitamin $B_1$ (P<0.05), and niacin (P<0.05) in women belonging to the 'Good' group were also significantly higher than that in the women assigned the 'Bad' group. The results of regression analysis on the relevance between the diet quality and SRH, MAR, and INQ showed a significantly positive relevance (P<0.001), even after adjusting for disturbance factors. The results of this study show that diet quality seems to be the important factor for improving SRH of women. Therefore, we suggest that developing dietary guidelines and educating women about the guidelines would improve health of middle-aged women in Korea.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.210-218
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• 2018

Background: Soil respiration (Rs) is a major factor of the absorption and accumulation of carbon through photosynthesis in the ecosystem carbon cycle. This directly affects the amount of net ecosystem productivity, which affects the stability and sustainability of the ecosystem. Understanding the characteristics of Rs is indispensable to scientifically understand the carbon cycle of ecosystems. It is very important to study Rs characteristics through analysis of environmental factors closely related to Rs. Rs is affected by various environmental factors, such as temperature, precipitation, soil moisture, litter supply, organic matter content, dominant plant species, and soil disturbance. This study was conducted to analyze the effects of micro-topographical differences on Rs in forest vegetation by measuring the Rs on the ridge and southern slope sites of the broadly established Quercus mongolica forest in the central Korean area. Method: Rs, Ts, and soil moisture data were collected at the southern slope and ridge of the Q. mongolica forest in the Mt. Jeombong area in order to investigate the effects of topographical differences on Rs. Rs was collected by the closed chamber method, and data collection was performed from May 2011 to October 2013, except Winter seasons from November to April or May. For collecting the raw data of Rs in the field, acrylic collars were placed at the ridge and southern slope of the forest. The accumulated surface litter and the soil organic matter content (SOMC) were measured to a 5 cm depth. Based on these data, the Rs characteristics of the slope and ridge were analyzed. Results: Rs showed a distinct seasonal variation pattern in both the ridge and southern slope sites. In addition, Rs showed a distinct seasonal variation with high and low Ts changes. The average Rs measurements for the two sites, except for the Winter periods that were not measured, were $550.1\;mg\;CO_2m^{-2}h^{-1}$ at the ridge site and $289.4\;mg\;CO_2m^{-2}h^{-1}$ at the southern slope, a difference of 52.6%. There was no significant difference in the Rs difference between slopes except for the first half of 2013, and both sites showed a tendency to increase exponentially as Ts increased. In addition, although the correlation is low, the difference in Rs between sites tended to increase as Ts increased. SMC showed a large fluctuation at the southern slope site relative to the ridge site, as while it was very low in 2013, it was high in 2011 and 2012. The accumulated litter of the soil surface and the SOMC at the depth range of 0~5 cm were $874g\;m^{-2}$ and 23.3% at the ridge site, and $396g\;m^{-2}$ and 19.9% at the southern slope site. Conclusions: In this study, Rs was measured for the ridge and southern slope sites, which have two different results where the surface litter layer is disturbed by strong winds. The southern slope site shows that the litter layer formed in autumn due to strong winds almost disappeared, and while in the ridge site, it became thick due to the transfer of litter from the southern slope site. The mean Rs was about two times higher in the ridge site compared to that in the southern slope site. The Rs difference seems to be due to the difference in the amount of litter accumulated on the soil surface. As a result, the litter layer supplied to the soil surface is disturbed due to the micro-topographical difference, as the slope and the change of the community structure due to the plant season cause heterogeneity of the litter layer development, which in turn affects SMC and Rs. Therefore, it is necessary to introduce and understand these micro-topographical features and mechanisms when quantifying and analyzing the Rs of an ecosystem.