• Journal of Korean Society of Water and Wastewater
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• v.34 no.4
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• pp.251-258
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• 2020

Sewer deterioration models are needed to forecast the remaining life expectancy of sewer networks by assessing their conditions. In this study, the serious defect (or condition state 3) occurrence probability, at which sewer rehabilitation program should be implemented, was evaluated using four probability distribution functions such as normal, lognormal, exponential, and Weibull distribution. A sample of 252 km of CCTV-inspected sewer pipe data in city Z was collected in the first place. Then the effective data (284 sewer sections of 8.15 km) with reliable information were extracted and classified into 3 groups considering the sub-catchment area, sewer material, and sewer pipe size. Anderson-Darling test was conducted to select the most fitted probability distribution of sewer defect occurrence as Weibull distribution. The shape parameters (β) and scale parameters (η) of Weibull distribution were estimated from the data set of 3 classified groups, including standard errors, 95% confidence intervals, and log-likelihood values. The plot of probability density function and cumulative distribution function were obtained using the estimated parameter values, which could be used to indicate the quantitative level of risk on occurrence of CS3. It was estimated that sewer data group 1, group 2, and group 3 has CS3 occurrence probability exceeding 50% at 13th-year, 11th-year, and 16th-year after the installation, respectively. For every data groups, the time exceeding the CS3 occurrence probability of 90% was also predicted to be 27th- to 30th-year after the installation.

• Journal of The Korean Astronomical Society
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• v.46 no.3
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• pp.133-140
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• 2013

The empirical mass discrepancy-acceleration (MDA) relation of disk galaxies provides a key test for models of galactic dynamics. In terms of modified laws of gravity and/or inertia, the MDA relation quantifies the transition from Newtonian to modified dynamics at low centripetal accelerations $a_c{\lesssim}10^{-10}ms^{-2}$. As yet, neither dynamical models based on dark matter nor proposed modifications of the laws of gravity/inertia have predicted the functional form of the MDA relation. In this work, I revisit the MDA data and compare them to four different theoretical scaling laws. Three of these scaling laws are entirely empirical; the fourth one - the "simple ${\mu}$" function of Modified Newtonian Dynamics - derives from a toy model of gravity based on massive gravitons (the "graviton picture"). All theoretical MDA relations comprise one free parameter of the dimension of an acceleration, Milgrom's constant aM. I find that the "simple ${\mu}$" function provides a good fit to the data free of notable systematic residuals and provides the best fit among the four scaling laws tested. The best-fit value of Milgrom's constant is $a_M=(1.06{\pm}0.05){\times}10^{-10}ms^{-2}$. Given the successful prediction of the functional form of the MDA relation, plus an overall agreement with the observed kinematics of stellar systems spanning eight orders of magnitude in size and 14 orders of magnitude in mass, I conclude that the "graviton picture" is sufficient (albeit probably not a necessary nor unique approach) to describe galactic dynamics on all scales well beyond the scale of the solar system. This suggests that, at least on galactic scales, gravity behaves as if it was mediated by massive particles.

• Research in Community and Public Health Nursing
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• v.19 no.1
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• pp.36-45
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• 2008

Purpose: This study was to estimate the prevalence of dementia in order to estimate the associations of dementia with its risk factors in the community elderly. Methods: The multistage random cluster sampling method was used to select the subjects. The response rate was 94.3%. For the 1st stage screening survey, the Korean-version Mini-Mental State Examination (K-MMSE) and the Bathel Index of activities of daily living (ADL) and instrumental activities of daily living (IADL) were used as primary screening tools. At the 2nd stage. diagnoses were confirmed according to the Clinical Dementia Rating Scale (CBR) and Computer Tomogram (CT). Results: Age-sex adjusted prevalence (%) [95% CI] of dementia was 6.25% [4.47-7.83] (male 4.21% [2.40-6.02]; female 8.28% [5.71-10.85]). Four statistically significant risk factors of the dementia were identified: age 70-74 (OR=1.367), age 75-79 (OR=1.712), age 80-84 (OR=2.465), age 85 over (OR=7.363) illiteracy (OR=3.827); unconsciousness after head injury (OR=3.383), and no exercise (OR=2.188). Hosmer and Lemeshow goodness-of-fit index of dementia risk model was E (legit of dementia)= -4.337+$0.312^*Age(70{\sim}74)+0.538^*Age(75{\sim}79)+0.902^*Age(80{\sim}84)+1.996^*Age$(85over)+$1.342^*$Illiteracy+$1.219^*$Unconsciousness after head trauma+$0.783^*$No exercise. We confirmed that the overall prevalence of dementia in adults aged 65 and older was 94.3%. The risk factors of dementia were explained by age, illiteracy unconsciousness after head trauma and no exercise. Conclusion: These data have been used to estimate the incidence of dementia in elderly community population and to manage the possible role of risk factors as predictors of dementia.

• Journal of Korean Public Health Nursing
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• v.16 no.2
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• pp.285-303
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• 2002

This descriptive correlational study was conducted to identify the variables related to a health promoting behavior in nursing students. 238 nursing students were selected by a convenience sampling method. The data were collected by self - reported questionnaires from 12 to November 19, 2001. The data were analyzed by using descriptive statistics, pearson correlation coefficient, stepwise multiple regression with an SPSS program. The result of this study were as follows: 1. The average score of health promoting behavior was 2.47(SD=0.36)of a 4 point scale. Self actualization (mean=2.94, SD=0.50), interpersonal support (mean=2.91, SD=0.53), stress management(mean=2.58, SD=0.48), health responsibility(mean=2.07, SD=0.48)) nutrition & exercise(mean=2.07, SD=0.48)) were also analyzed. 2. Health promoting behavior showed significant positive correlations with self­esteem(r=0.446, p<0.001) perceived health status(r=0.180, p<0.01), perceived benefits (r=0.183. p<0.01). self-efficacy(r=0.311, p<0.001), social support(r=0.447, p<0.001), control(r=0.169, p<0.01). 3. The combination of self-esteem, social support, affect related to action explained $38.0\%$ of the variance in health promoting behavior. On the basis of the above findings. self-esteem and social support were identified as the variables which explained most of Pender's health promoting model. Nursing strategies enhancing self-esteem and social support which have a more significant effect on health promoting lifestyles should be developed.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.1-6
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• 2015

This paper investigates the longitudinal flight dynamics and stability of flapping-wing micro air vehicles. Periodic external forces and moments due to the flapping motion characterize the dynamics of this system as NLTP (Non Linear Time Periodic). However, the averaging theorem can be applied to an NLTP system to obtain an NLTI (Non Linear Time Invariant) system which allows us to use a standard eigen value analysis to assess the stability of the system with linearization around a reference point. In this paper, we investigate the dynamics and stability of a hawkmoth-scale flapping-wing air vehicle by establishing an LTI (Linear Time Invariant) system model around a hovering condition. Also, a direct time integration of full nonlinear equations of motion of the flapping-wing micro air vehicle is conducted to see how the longitudinal flight dynamics appear in the time domain beyond the reference point, i.e. hovering condition. In the study, the flapping-wing air vehicle exhibited three distinct dynamic modes of motion in the longitudinal plane of motion: two stable subsidence modes and one unstable oscillatory mode. The unstable oscillatory mode is found to be a combination of a pitching velocity state and a forward/backward velocity state.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.15-24
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• 2000

The dielectric relaxation of high-dielectric capacitors could be understood as a dynamic property of the capacitor in the time domain, which is regarded as a primarily important charge loss mechanism during the refresh time of DRAMs. Therefore, the equivalent circuit of the dielectric relaxation of the high-dielectric capacitor is essentially required to investigate its effects on DRAM. Nevertheless, There is not any theoretical method which is generally applied to realize the equivalent circuit of the dielectric relaxation. Recently, we have developed a novel procedure for the circuit modeling of the dielectric relaxation of high-dielectric capacitor utilizing the frequency domain. This procedure is a general method based on theoretical approach. We have also verified the feasibility of this procedure through experimental process. Finally, we successfully investigated the effect of dielectric relaxation on DRAM operation with the obtained equivalent circuit through this new method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.10
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• pp.794-801
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• 2017

In this paper, we proposed airborne target recognition using multi-channel combining method in DTV-based passive radar. By combining multi-channel signals, we obtained the HRRP with sufficient range resolution. HRRP was obtained by AR method or zero-padding. From the obtained HRRP, we extracted scattering centers by CLEAN algorithm using the gradient descent. We extracted feature vectors and performed target recognition after training neural network using the extracted feature vectors. To verify performance of proposed methods, we assumed frequency bands of three broadcasting transmitters operated in Korea(Mt. Gwan-ak, Mt. Yong-moon, Kyeon-wol-ak) and used full scale 3D CAD model of four targets. Also we compared the target recognition performance of the proposed method with that of using only single-channel of three broadcasting transmitters. As a result, proposed methods showed better performance than using only single-channel at three broadcasting transmitters.

• Journal of Ecology and Environment
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• v.40 no.2
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• pp.107-119
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• 2016

Background: Previous studies on the biological integrity on habitat and landuse patterns demonstrated ecological stream health in the view of regional or macrohabitat scale, thus ignored the mesoscale habitat patterns of pool, riffle, and runs in the stream health analysis. The objective of this study was to analyze influences on the mesohabitat structures of pool, riffle, and run reaches on the fish guilds and biological integrity in Geum-River Watershed. Results: The mesohabitat structures of pool, riffle, and run reaches influenced the ecological stream health along with some close relations on the fish trophic and tolerance guilds. The mesoscale components altered chemical water quality such as nutrients (TN, TP) and BOD and these, then, determined the primary productions, based on the sestonic chlorophyll-a. The riffle-reach had good chemical conditions, but the pool-reach had nutrient enrichments. The riffle-reach had a predominance of insectivores, while the pool-reach has a predominance of omnivores. Also, the riffle-reach had high proportions of sensitive fish and insectivore fish, and the pool-reach had high proportions of tolerant species in the community composition. The intermediate fish species in tolerance and omnivorous fish species in the food linkage dominated the community in the watershed, and the sensitive and insectivorous fishes decreased rapidly with a degradation of the water quality. All the habitat patterns were largely determined by the land-use patterns in the watershed. Conclusions: Trophic guilds and tolerance guilds of fish were determined by land-use pattern and these determined the stream health, based on the Index of Biological Integrity. This study remarks the necessity to include additional variables to consider information provided by mesohabitats and land-use distributions within the selected stream stretch. Overall, our data suggest that land-use pattern and mesohabitat distribution are important factors to be considered for the trophic and tolerance fish compositions and chemical gradients as well as ecological stream health in the watershed.

• Korean Journal of Health Education and Promotion
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• v.33 no.1
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• pp.23-32
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• 2016

Objectives: The aim of this study was to examine the effects of home-based cognitive physico-occupational therapy(HBCPOT) on cognitive function, depression, and quality of life in dementia patients, using a cognitive impairment model. Methods: The data was analysed for Mini-Mental State Examination-Korean version (MMSE-KC) for assessing cognitive function, Quality of life-Alzheimer's Disease (QOL-AD) and Geriatric Depression Scale (GDS) in 31 dementia patients who received home-based cognitive physico-occupational therapy for one hour once a week for 12 weeks by a trained occupational therapist at the Dementia Prevention and Management Center of Y-city during 20111-2013. Results: Among these 31 patients, 18(58.1%) were female, and 25(80.6%) had Alzheimer's Disease. After HBCPOT, the mean scores of MMSE-KC and QOL-AD were significantly improved, but GDS score was not significantly decreased. Conclusions: It was suggested that HBCPOT was effective in improving cognitive function and quality of life.

• Journal of Families and Better Life
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• v.9 no.2
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• pp.303-322
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• 1991

The aim of present study was to explore there were relationships among familism(collectivism vs. individualism), filial responsibility, and helping behavior of the middle-aged women towards parents. The respondents were 552 married women in their thirties, forties and fifties. OK Sun-hwa(1989)'s Seelbach (1978)'s, Cicirelli (1983)'s and Chang Sun-ju(1989)'s scale were utilized to tap the familism, filial responsibility, and helping behavior of the middle age daughter and daughter in low respectively. The major results of the study were summerized as follows; 1) Married women perceived relatively high levels of familism and filial responsibility and a moderate level of helping towards their parents and in-law parents as well. Among the demographic variables, education, income and age of the married daughters and daughters-in-law were found to be correlated to both familism and filial responsibility of support for their parents, Also, education and age were negatively related to helping behaviors. 2) Marred women reported similar levels of filial responsibility of support towards parents in law and their own parents, However significant difference were found between the amounts of helping behavior towards parents-in-law and their own parents. 3) Regression analysis revealed that living arrangement(living with parents or not ), the level of filial responsibility , and education level provided to be significant predictors on the helping behavior towards parent-in-law explaining 46% of the total variance. On the other hand, filial responsibility , living pattern, and income level for the parents were powerflu in predicting helping behavior towards their own parents accounting 24% of the total explained variance. 4) A path analysis model indicated that while educational level and living arrangement influenced directly to helping behavior toward parent-in-law, living arrangement, income level of parents and familism were directly associated with helping behavior for parents of their own. Therefor , helping behavior of the middles aged women was significantly mediated by familism and filial responsibility for support towards both parents-in-law and their own parents.