• Korean Journal of Psychosomatic Medicine
• /
• v.27 no.2
• /
• pp.173-180
• /
• 2019

Objectives : Loneliness is associated with negative mental and physical health. However, little is known about the risk factors of loneliness in the Korean elderly living alone. The aim of this study was to examine sociodemographic and social network related risks for loneliness among the elderly living alone. Methods : This is a cross-sectional study that enrolled 1,091 subjects who are the community-residing elderly living alone. Sociodemographic status, medical condition, cognition, mood disorder and levels of loneliness were collected using a self-administered questionnaire and a specific semi-structured interview conducted by a trained nurse. Descriptive statistics were used to analyze data regarding sociodemographic variable and loneliness. Univariate and Multivariate regression analyses were applied to examine factors associated with loneliness. Results : The mean score of loneliness was 3.8 (SD=1.7). No family contact (standardized β=0.115, p<0.001), no religious attendance (standardized β=0.057, p=0.028), no gathering with friends (standardized β=0.088, p=0.001) and high score of Short for of Geriatric Depression Scale (standardized β=0.502, p<0.001) were significantly associated with high loneliness in the elderly living alone. Conclusions : Family function, social network and depressive mood could be significant risk factors for high loneliness in the elderly living alone. Public health promotion efforts to reduce loneliness should focus on improving family function, social network and decreasing depression.

• Environmental and Resource Economics Review
• /
• v.25 no.2
• /
• pp.199-228
• /
• 2016

This study investigates the effects of economic factors and forest environments on rural residential area development in seven north central states of the U.S. by focusing on the relative importance of not only economic factors but also forest environments by forest type as core drivers of residential development. An empirical model of locations and magnitudes of population changes since 1950 in the north central region is first constructed, and then a panel model with fixed effects for counties is used to explain population growth by age group over time at the county level. Then a set of three equations is estimated for three major age groups, and a cross-sectional model is estimated for the last time period that regresses county-level environmental amenity variables on fixed effects coefficients for counties. Finally, an equation explaining changes in rural housing density is estimated. The results imply that immigrant age is a key factor influencing the choice of the place of residence and that the effects of environmental amenity factors on population growth and subsequent housing development in a county vary according to the age group.

• The Korean Journal of Community Living Science
• /
• v.20 no.3
• /
• pp.413-421
• /
• 2009

The purpose of this study was to analyze the patterns and the interrelationships for meeting guidelines of three health behaviors including physical activity(PA), sedentary behavior(SB), and dietary behavior(DB) for Korean adolescents using 2007 KYRBS(Korea Youth Risk Behavior Survey) data. A cross-sectional design was used to assess 73392 middle-high school students. PA(moderate physical activity${\geqq}$5times/week, or vigorous ${\geqq}$3times/week), SB(watching TV, computer, DVD, video, etc. < 3 hr/day), and DB(servings of fruits ${\geqq}$1 times/day, or vegetables ${\geqq}$ 3 times/day) were categorized into two levels (meeting guidelines or not). Chi-squared tests were conducted to compare the prevalence of students not meeting these three health behaviors between boys and girls, and logistic linear regression was used to determine the interrelationships of three health behaviors. Students meeting guidelines for PA, SB, and DB were 31.0%(boys 42.6%, girls 18.0%), 74.7%(boys 75.4%, girls 74.0%), and 38.5%(boys 38.6%, girls 38.4%), respectively. In addition, there were significant differences between both genders for PA and SB (PA; $x^2(1)$=35175.11, p<.0001, SB; $x^2(1)$=19.44, p<.0001). Only 10.9% of students met all three guidelines and 12.4% did not meet all three. Pattern that simultaneously did not meet PA and DB were high in both boys(27.1%) and girls(37.2%). Students who did not meet DB were at greater risk of not meeting PA(Boys; OR 1.49, 95% CI 1.43 to 1.55, Girls; OR 1.42, 95% CI 1.34 to 1.50), and not meeting SB(Boys; OR 1.41, 95% CI 1.34 to 1.48, Girls; OR 1.36, 95% CI 1.29 to 1.43) compared with students who met DB. The findings of this study supported further evidence for the need of a multiple behavior approach considering gender and interrelationships among three behaviors.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.2A
• /
• pp.75-83
• /
• 2012

In this study, an analytical studies were carried out for the buoyancy preflexion method to improve structural performance of concrete floating structures. The buoyancy preflexion means that the preflexion effects were induced to the floating structure due to the difference in buoyancy between the pontoon modules composing the floating structures. In order to verify the buoyancy preflexion effects, an analytical studies were carried out for the floating structures. The size and dimensions of FE model were determined through the structural design process. The parameter of this analytical study was length ratios of central module part, which induces buoyancy preflexion effects, to the total length. The analysis results were pre-compression on the bottom concrete slab and displacement of freeboard due to buoyancy preflexion effects. These results were processed according to the loading step, buoyancy preflexion loads on the bottom and live loads on the topside. Then, the buoyancy preflexion effects on structural performance was analyzed. As the results of this study, it was found that the buoyancy preflexion significantly influence on structural performance of floating structures. According to the length ratio, the buoyancy preflexion effects have a tendency of parabolic form and maximized at the length ratio of 40~60%. The buoyancy preflexion method is simple in principle and easy in application. Also, it can effectively induce pre-compression on the bottom concrete slab. Therefore, it can be concluded that the buoyancy preflexion method contribute to the improvement of structural performance and decreasing of the cross-sectional depth of floating structures.

• Korean Journal of Community Nutrition
• /
• v.6 no.4
• /
• pp.604-616
• /
• 2001

This study was to investigate weight-control experience disorder and nutrient intake of college student attending web class via the internet. The subject were 1200 college students(392 male, 808 female) attending web class concerned with nutrition and weight control. This cross-sectional survey was conducted by self-administered questionnaire and data were analyzed by Students t-test and $\chi$$^2$-test. Nutrient intake collected from 3 day-recalls were analyzed by the Computer Aided Nutritional Analysis Program. Mean height, weight and RBW(relative body weight) of the male college students were 174.7 cm, 68.0 kg and 101.2%, respectively. Mean height, weight and RBW of the female college students were 162.3% cm, 52.7% kg and 95.3% respectively. Among the male college students, low weight were 1.0%, underweight were 12.8%, overweight were 12.5%, obese were 6.9% by RBW standard. Among the female college students, low weight were 5.1%, underweight 30.2%, overweight were 5.2%, obese were 1.5% by RBW standard. Percentages of weight control experience were 21.7% and 67.0% in the male and female college students, respectively. According to RBW, 22.4% of the weight control experience group were low weight or underweight in the female college students but none of weight control experience group were low weight or underweight in the male college students. Percentage of eating disorder were 6.8%(2.8%, male, 8.7% female) in the college students. Among the female college students, most nutrient intakes were significantly lower in the weight-control experienced group compared to the weight-control nonexperienced group. Among the male college students, there was a tendency that the intake of nutrients, except carbohydrate, calcium and vitamin A was higher in the eating disorder group compared to the non-eating disorder group. However, among the female college students, there was a tendency that the intake of nutrients, except calcium and thiamin was lower in the eating disorder group compared to the non-eating disorder group. Therefore, nutrition education via the internet is required for college students to know proper weight loss methods, desirable eating habits and eating disorder problem well.

• Korean Journal of Community Nutrition
• /
• v.21 no.2
• /
• pp.178-189
• /
• 2016

Objectives: The objectives of the study were to assess body composition, physical activity level (PAL), basal metabolic rate (BMR), and daily energy expenditure (DEE) and to examine associations between PAL and body composition, BMR, and DEE of elderly in Busan. Methods: A cross-sectional study was conducted among 226 elderly aged 65-93 years. Body composition was measured by Inbody 720. PAL was calculated by daily activity diary. BMR was calculated by Harris-Benedict (H-B) formula, Dietary Reference Intakes (DRI) formula, and Inbody 720 measurement. DEE was calculated by H-B formula, DRI formula, Inbody 720 measurement, and estimated energy requirements (EER) formula. Results: The mean fat free mass (FFM) in elderly men was significantly higher than that in elderly women (p<0.001). The mean percent body fat and fat mass (FM) in elderly women were significantly greater than those in elderly men (p<0.001, p<0.001). The mean PAL in elderly men (1.59) was significantly higher than that in elderly women (1.53) (p<0.001). The mean DEEs calculated by 3 methods except for H-B formula in elderly men were higher than EER for elderly men (2000kcal). The mean DEEs calculated by 4 different methods in elderly women were higher than EER for elderly women (1600kcal). Age showed significantly negative correlations with height (p<0.001, p<0.001), FFM (p<0.001, p<0.001), BMRs calculated by H-B formula (p<0.001, p<0.001), DRI formula (p<0.001, p<0.001) and Inbody 720 measurement (p<0.05 p<0.01) and DEEs calculated by H-B formula (p<0.001, p<0.001), DRI formula (p<0.001, p<0.001), Inbody 720 measurement (p<0.05, p<0.05), and EER formula (p<0.001, p<0.001) in elderly men and elderly women. PAL showed significantly positive correlations with FFM (p<0.05), BMR by Inbody 720 measurement (p<0.05) in elderly men and negative correlations with FM (p<0.05) in elderly women. Conclusions: Based on the results, PAL was associated with greater FFM in elderly men and lesser FM in elderly women. Therefore, nutritional education to increase physical activity for health promotion in late life is needed in the elderly.

• Korean Journal of Community Nutrition
• /
• v.19 no.6
• /
• pp.537-549
• /
• 2014

Objectives: This study was conducted to examine blood pressure and other characteristics of a high sodium intake group assessed with 24-hr urine analysis and the dietary factors related to the risk of high sodium intake among Korean adults. Methods: A cross-sectional study was conducted with adults aged 20-59 years. Subjects who completed 24-hr urine collection (N = 205) were divided into 3 groups (tertile) according to the sodium intake estimated with 24-hour urine analysis. We compared the blood pressure, BMI and dietary related factors of the 3 groups (low, medium, high sodium intake group) with General Linear Model (GLM) and Duncan's multiple range test (p < 0.05). The risk factors related to high sodium intake were assessed with odds ratio (p < 0.05). Results: The sodium intake (mg/day) of the 3 groups were $3359.8{\pm}627.9$, $4900.3{\pm}395.1$ and $6770.6{\pm}873.9$, respectively, corresponding to daily salt intake (g/day) 8.5, 12.4 and 17.2, respectively. High sodium group showed significantly elevated age, BMI and systolic/diastolic blood pressure. Being male gender was associated with significantly increased risk of sodium intake (OR = 1.972; 95%CI: 1.083-3.593). The other factors related to high sodium intake were higher BMI (${\leq}25$) (OR = 2.619; 95% CI: 1.368-5.015), current alcohol consumption (OR = 1.943; 95%CI: 1.060-3.564), and having salty soybean paste with salt percentage > 14% (OR = 3.99; 95% CI: 1.404-6.841). The dietary attitude related to increased risk of high sodium intake included 'enjoy dried fish and salted mackerel' (p < 0.001) and 'eat all broth of soup, stew or noodle' (p < 0.001). Conclusions: Because high sodium intake was associated with higher blood pressure, nutrition education should focus on alcohol consumption, emphasis on related dietary factors such as using low salt soybean paste, improvements in the habit of eating dried fish and salted mackerel or eating all broth of soup, stew or noodle.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.5
• /
• pp.393-400
• /
• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Journal of Distribution Science
• /
• v.13 no.5
• /
• pp.53-60
• /
• 2015

Purpose - The purpose of this paper is to shed light on the importance of the slope and curvature of the volatility curve implied in option prices in the KOSPI 200 options index. A number of studies examine the implied volatility curve, however, these usually focus on cross-sectional characteristics such as the volatility smile. Contrary to previous studies, we focus on time-series characteristics; we investigate correlation dynamics among slope, curvature, and level of the implied volatility curve to capture market information embodied therein. Our study may provide useful implications for investors to utilize current market expectations in managing portfolios dynamically and efficiently. Research design, data, and methodology - For our empirical purpose, we gathered daily KOSPI200 index option prices executed at 2:50 pm in the Korean Exchange distribution market during the period of January 2, 2004 and January 31, 2012. In order to measure slope and curvature of the volatility curve, we use approximated delta distance; the slope is defined as the difference of implied volatilities between 15 delta call options and 15 delta put options; the curvature is defined as the difference between out-of-the-money (OTM) options and at-the-money (ATM) options. We use generalized method of moments (GMM) and the seemingly unrelated regression (SUR) method to verify correlations among level, slope, and curvature of the implied volatility curve with statistical support. Results - We find that slope as well as curvature is positively correlated with volatility level, implying that put option prices increase in a downward market. Further, we find that curvature and slope are positively correlated; however, the relation is weakened at deep moneyness. The results lead us to examine whether slope decreases monotonically as the delta increases, and it is verified with statistical significance that the deeper the moneyness, the lower the slope. It enables us to infer that when volatility surges above a certain level due to any tail risk, investors would rather take long positions in OTM call options, expecting market recovery in the near future. Conclusions - Our results are the evidence of the investor's increasing hedging demand for put options when downside market risks are expected. Adding to this, the slope and curvature of the volatility curve may provide important information regarding the timing of market recovery from a nosedive. For financial product distributors, using the dynamic relation among the three key indicators of the implied volatility curve might be helpful in enhancing profit and gaining trust and loyalty. However, it should be noted that our implications are limited since we do not provide rigorous evidence for the predictability power of volatility curves. Meaning, we need to verify whether the slope and curvature of the volatility curve have statistical significance in predicting the market trough. As one of the verifications, for instance, the performance of trading strategy based on information of slope and curvature could be tested. We reserve this for the future research.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.1 no.1
• /
• pp.86-98
• /
• 1998

In order to provide an information as input data of possible storm surges in advance, the typhoon center and maximum wind position analysis scheme must be developed for the initialization of pressure and wind field.This study proposes a semi-automatical and objective analysis method and a procedure on a real time basis using the satellite TBB data of the GMS IR1, NOAA satellite CH4 and CH5, and shows the result of an experimental analysis. It includes a simple method of determining the parameters of the typhoon using minimum top temperature of the convective cloud near the inner eyewall. The method analyzing the isotropic cross sectional variation of TBB gradient from center to environment was developed to determine the center of Rmax of typhoon. This position of intense eyewall from typhoon center can be considered as the position of maximum wind. The results of estimation of typhoon center show very good agreement to the results of synoptic analysis. It is found that the Rmax is approximately 50-200km. From the comparison of the GMS and NOAA IR TBB data, it is found that the Rmax from NOAA data tends to be longer than those from GMS data.