• Journal of The Korean Astronomical Society
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• v.36 no.3
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• pp.89-95
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• 2003

Observations of dark matter dominated dwarf and low surface brightness disk galaxies favor density profiles with a flat-density core, while cold dark matter (CDM) N-body simulations form halos with central cusps, instead. This apparent discrepancy has motivated a re-examination of the microscopic nature of the dark matter in order to explain the observed halo profiles, including the suggestion that CDM has a non-gravitational self-interaction. We study the formation and evolution of self-interacting dark matter (SIDM) halos. We find analytical, fully cosmological similarity solutions for their dynamics, which take proper account of the collisional interaction of SIDM particles, based on a fluid approximation derived from the Boltzmann equation. The SIDM particles scatter each other elastically, which results in an effective thermal conductivity that heats the halo core and flattens its density profile. These similarity solutions are relevant to galactic and cluster halo formation in the CDM model. We assume that the local density maximum which serves as the progenitor of the halo has an initial mass profile ${\delta}M / M {\propto} M^{-{\epsilon}$, as in the familiar secondary infall model. If $\epsilon$ = 1/6, SIDM halos will evolve self-similarly, with a cold, supersonic infall which is terminated by a strong accretion shock. Different solutions arise for different values of the dimensionless collisionality parameter, $Q {\equiv}{\sigma}p_br_s$, where $\sigma$ is the SIDM particle scattering cross section per unit mass, $p_b$ is the cosmic mean density, and $r_s$ is the shock radius. For all these solutions, a flat-density, isothermal core is present which grows in size as a fixed fraction of $r_s$. We find two different regimes for these solutions: 1) for $Q < Q_{th}({\simeq} 7.35{\times} 10^{-4}$), the core density decreases and core size increases as Q increases; 2) for $Q > Q_{th}$, the core density increases and core size decreases as Q increases. Our similarity solutions are in good agreement with previous results of N-body simulation of SIDM halos, which correspond to the low-Q regime, for which SIDM halo profiles match the observed galactic rotation curves if $Q {\~} [8.4 {\times}10^{-4} - 4.9 {\times} 10^{-2}]Q_{th}$, or ${\sigma}{\~} [0.56 - 5.6] cm^2g{-1}$. These similarity solutions also show that, as $Q {\to}{\infty}$, the central density acquires a singular profile, in agreement with some earlier simulation results which approximated the effects of SIDM collisionality by considering an ordinary fluid without conductivity, i.e. the limit of mean free path ${\lambda}_{mfp}{\to} 0$. The intermediate regime where $Q {\~} [18.6 - 231]Q_{th}$ or ${\sigma}{\~} [1.2{\times}10^4 - 2.7{\times}10^4] cm^2g{-1}$, for which we find flat-density cores comparable to those of the low-Q solutions preferred to make SIDM halos match halo observations, has not previously been identified. Further study of this regime is warranted.

• Child Health Nursing Research
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• v.21 no.1
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• pp.20-27
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• 2015

Purpose: The purpose of this study was to investigate factors affecting childhood asthma and atopic dermatitis. Methods: For this study, data for 1,170 children (1-11 years) from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES V-2, 2011) were analyzed. First correlation matrices were computed to test the normality of every data set and then to be in accordance with the real demographic composition, data were added weight before being analyzed. Results: The child with asthma of a three generation family (OR=3.91, 95% CI [1.33, 11.45], p=.013) compared with a two generation family showed higher asthma development, and maternal asthma (OR=9.71, 95% CI [2.66, 35.40], p=.001) showed higher asthma development in child. The only factor affecting atopic dermatitis was parental perceptions of child health: poor (OR=3.40, 95% CI [1.29, 8.98], p=.014). Conclusion: These results suggest that childhood asthma and atopic dermatitis are both affected by parental perceptions of child health. Accordingly, management and support programs for children who have asthma and/or atopic dermatitis and their families should be comprehensive and also give attention to any other health problems because health perception represents quality of life.

• Korea journal of population studies
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• v.28 no.2
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• pp.165-182
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• 2005

The main purposes of this study are to describe the elderly dementia, and to explore characteristics of the elderly dementia among the aged 65 and over in Daegu area. In this study, 1,120 subjects which were 0.6 percent of the population were selected and face-to-face interviews were conducted. The face-to-face interviews were conducted from July 1, 2004 to August 31, 2004. KMMSE was introduced to measure the status of the interviewees' dementia. The findings of this study are as follows: 8.9 percent of respondents turns out to be dementia patients. Among the dementia patients, 52.5 percent are mild dementia patients, 35.0 percent are mid-level symptoms and 12.5 percent are severe symptoms of dementia patients. Cross-tabulation analyses and logistic regression analysis were introduced to explore the demographic, living, and behavioral differentials of the elderly's dementia. According to the logistic regression analysis, it turns out that white educational attainment, participating in the leisure activities for both physical exercise and mental activities, having meals regularly, adequate amount of meals, and high economic status decrease the odds ratio of elder dementia among the elderly who are 65 and above in Daegu area and are statistically significant. On the other hand, age increases the odds ratio of the elder dementia of the elder among Koreans above 65 in Daegu area. Finally, policy implications and some suggestions for the improvement of the elder dementia are introduced and discussed.

• Korean Journal of Community Nutrition
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• v.19 no.2
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• pp.163-175
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• 2014

Objectives: We aimed to evaluate dietary intake among female breast cancer survivors in a cross-sectional study. Methods: A total of 127 women who had breast cancer surgery at least 6 months before baseline were included. Dietary intake of female breast cancer survivors was assessed through self-reported 3 day-dietary records. To compare dietary intake between breast cancer survivors and general female population without cancer, we selected the 1:4 age matched women from the 2011 Korean National Health and Nutrition Examination Survey (KNHANES). In the KNHANES, participants were asked about their dietary intake using the 24-hour dietary recalls. We also examined whether dietary intake varied by age group, cancer stage, or time since surgery among breast cancer survivors. We used the generalized linear model to compare their dietary intakes. Results: Intakes of total energy, beta-carotene, folate, vitamin C, plant iron and fruits were lower among breast cancer survivors with longer time since surgery compared to those with shorter time (p<0.05). Breast cancer patients with higher stage at diagnosis tended to consume less legumes (p=0.01) than those with lower stage. When we compared dietary intake between breast cancer survivors and the general female population without cancer, breast cancer survivors were more likely to consume most of macro- and micro-nutrients in larger quantity (p<0.05) and adhere to healthier diet characterized by higher intakes of legumes, seed and nuts, vegetables and fishes and shells than the general female population who never had been diagnosed with cancer (p<0.05). Conclusions: Our study results suggested that the intakes of nutrients and foods varied by time since surgery and cancer stage among breast cancer survivors and dietary intakes among breast cancer survivors differed from that in the general population. Further prospective studies are warranted to explore the association between dietary intakes of specific food items and survival among Korean breast cancer survivors.

• Journal of Korean society of Dental Hygiene
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• v.5 no.2
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• pp.171-184
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• 2005

In order to investigate correlation between mother's dental ca re for her children and their dental caries, this study was conducted wi th the dental examination record of 365 children who showed the same number of questionnaires with those examined for dental conditions and questionnaires written by mothers among children between three and six years of age and their mothers in Yeoncheon, Gyeonggi province in June 2004 to estimate frequency and percentage of general properties of subjects and mother's oral health care behaviors for her children by research items, to carry out cross-tabulation analysis and correlation analysis following Chi-square distribution for the presence of dental caries in deciduous teeth and oral health care behaviors, and to use decision tree analysis among data mining techniques for those factors associated with the presence of dental caries in deciduous teeth, and drew the following conclusions. 1. For mother's oral health care behaviors and attitudes for her children, 225 mothers(61.6%) confirmed their children's teeth-brushing; 278(76.2%) used no fluorine; and 286(78.6%) observed their children's teeth, 322 mothers(88.2%) instructed their children in teeth-brushing while 268 (73.4%) provided dental care, 232 mothers(63.7%) treated their children's cavity; 290(79.4%) believed that their children had good dental conditions; and 294(80.5%) answered that they began to provide their children with dental care in deciduous teeth. 2. As for the presence of dental caries in deciduous teeth and dental health care behaviors, there were statistically significant differences in employment, confirmation after teeth-brushing, teeth observation, instruction in time for teeth-brushing, use of fluorine, cavity treatment, time for dental care, and perception of dental conditions(p<0.05). 3. As for correlation between dental caries in deciduous teeth and oral health care behaviors, mothers who worked, who believed that their children didn't have good dental condition, and who thought that it was necessary to begin to provide dental care in permanent teeth were found to get their children to suffer from dental caries in deciduous teeth. Besides, those who failed to confirm teeth-brushing, who used no fluorine, and who failed to observe teeth and gave no instruction in time for teeth-brushing were shown to get their children to suffer from dental caries in deciduous teeth. 4. Variables to determine the presence of dental caries in deciduous teeth were classified by cavity treatment, mother's employment, time for dental care, and observation of children's teeth. The first node to determine the presence of dental caries in deciduous teeth was found to be cavity treatment; the next criteria for classification after cavity treatment were shown to be mother's employment and time for dental care. In case of children with no cavity, they were found to be mother's employment and teeth observation.

• Journal of Korean society of Dental Hygiene
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• v.20 no.3
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• pp.313-324
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• 2020

Objectives: The aim of this study was to confirm the association among the health status, health behaviors, and periodontitis according to total, age and sex in cases of adult metabolic syndrome(MetS). Methods: This cross-sectional study used collected data from the 7^th Korea National Health and Nutrition Examination Survey (KNHANES) conducted from 2016 to 2018 with 3,394 adults with MetS aged 19-79 years. The complex samples logistic regression analysis confirmed the relevant factors for periodontitis. Results:Periodontitis was diagnosed in 43.6% of all MetS cases. Diabetes (Odds Ratio [OR]=1.554), abdominal obesity (OR=1.336), current smoking (OR=2.465), past smoking (OR=1.379), and not-using oral care products (OR=1.414) were associated with periodontitis in MetS. In the age of 19-39 years with MetS group, diabetes (OR=5.379), elevated blood pressure (OR=3.975), current smoking (OR=7.430), and not using oral care products (OR=3.356) were associated with periodontitis. In the 40-79 age group, diabetes (OR=1.398), abdominal obesity (OR=1.360), current smoking (OR=2.022), and not using oral care products (OR=1.416) were associated with periodontitis. In the male MetS group, current smoking (OR=3.119), past smoking (OR=1.625), and brushing teeth more than three times (OR=0.743) were associated with periodontitis. In the female MetS group, diabetes (OR=1.733), impaired fasting glucose (OR=1.434), abdominal obesity (OR=1.479), and not using oral care products (OR=1.992) were associated with periodontitis. Conclusions: Improvement in blood sugar control, obesity, smoking cessation, and oral health education, including how to use oral care products in all individuals with MetS may result in improved oral health. In addition, improvement in elevated blood pressure in the MetS group aged under 40 years, and brushing teeth more than three times a day in the male MetS group can reduce the risk of periodontitis. Therefore, public and oral health professionals should emphasize on the relationship between age and sex during the metabolic syndrome management program and share relevant information with patients.

• Nutrition Research and Practice
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• v.12 no.2
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• pp.160-165
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• 2018

BACKGROUND/OBJECTIVES: Korea is quickly becoming an aged society. Dementia is also becoming a vital public health problem in Korea. Cognitive impairment as a pre-stage of dementia shares most risk factors for dementia. The aim of the present study was to determine associations of serum levels of vitamins A, C, and E with the risk of cognitive impairment among elderly Koreans. SUBJECTS/METHODS: In this cross-sectional study, a total of 230 participants aged 60-79 years from Yangpyeong cohort were included. Cognitive function was assessed by the Korean version of the Mini-Mental State Examination for Dementia Screening. The logistic multivariable regression model was applied to determine the effect of serum vitamins A, C, and E on the risk of cognitive impairment. RESULTS: There was no significant association between the risk of cognitive impairment and serum levels of vitamin A and vitamin C. There was a significant odd ratio when the second tertile group of beta-gamma tocopherol level was compared to the first tertile group [odds ratio (OR) = 0.37, 95% confidence interval (CI) = 0.14-0.98, P for trend = 0.051]. In subgroup analyses, there were significant negative associations between beta-gamma tocopherol level and the risk of cognitive impairment in men (OR = 0.17, 95% CI = 0.03-0.87, P for trend = 0.028), non-drinkers or former drinkers (OR = 0.13, 95% CI = 0.02-0.66, P for trend = 0.025), and non-smokers or former smokers (OR = 0.27, 95% CI = 0.09-0.82, P for trend = 0.017). CONCLUSION: Serum beta-gamma tocopherol levels tended to be inversely associated with the risk of cognitive impairment. Further prospective large-scaled studies are needed to examine this association.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.508-526
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• 1995

This experiment was performed to study mechanisms of desensitization by chemical desensitizing agents in hypersensitive dentin and compare effects of these agents by measuring the activity of intradental nerves and observing their occluding aspects on dentinal tubules with SEM over time after application of chemical desensitizing agents to the exposed dentinal surfaces. Canines of adult cats weighing 2-3 kg were cross-sectioned at 1.5 mm from incisal apex, and the smear layer of the exposed dentinal susface was removed by 32 % $H_3PO_4$ for 15 sec. Chemical desensitizing agents such as 10% $SrCl_2$, 5% $KNO_3$ and 30% $K_2C_2O_4$, were applied to the exposed dentin surfaces for 2 minutes. Intradental nerve activity was measured immediately after application of the agents, at 15 minutes and at 30 minutes by stimulating with 4M NaCl. To compare occluding ability of desensitizing agents on dentinal tubules in vivo and in vitro, the structures of the exposed dentinal surfaces of nonvital and vital teeth were morphologically observed by SEM. The results obtained were as follows : 1. Intradental nerve activity was decreased immediately after the application of 10 % $SrCl_2$, 5% $KNO_3$ and 30% $K_2C_2O_4$. (p<0.01), among which 30% $K_2C_2O_4$. showed the highest desensitizing effect(p<0.01). 2. The immediately decreased intradental nerve activity after application of 10 % $SrCl_2$ and 5% $KNO_3$ was increased over time. 10% $SrCl_2$ and 5% $KNO_3$ showed no desensitizing effect respectively at 30 minutes and at 15 minutes after application. 3. The immediately decreased intradental nerve activity after application of 30 % $K_2C_2O_4$ was persistently continued during the period of observation (p<0.01). 4. Precipitates of $SrCl_2$ and $KNO_3$ were not noted on the exposed dentinal surfaces and within dentinal tubules by SEM examination. On the other hand, 30 % $K_2C_2O_4$ produced precipitates on the exposed dentinal surfaces and openings of dentinal tubules without any formed preciptates within dentinal tubules. 5. Ten percent $SrCl_2$, 5 % $KNO_3$ and 30 % $K_2C_2O_4$ showed no differences in their occluding aspects on dentinal tubules either in vivo or in vitro studies and either immediately following application or at 30 minutes. These results suggest that the desensitizing effect of $SrCl_2$ and $KNO_3$ is resulted from their reducing effect on the intradental nerve activity rather than from their precipitates' occluding the dentinal tubules. However, desensitizing effect of 30 % $K_2C_2O_4$, is probably resulted from its precipitates' occluding the openings of the dentinal tubules as well as from it's reducing effect on the intradental nerve actibity.

• Journal of radiological science and technology
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• v.35 no.2
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• pp.133-139
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• 2012

For the examination of nuclear medicine, myocardial scan is a good method to evaluate a hemodynamic importance of coronary heart disease. but, the automatized qualitative measurement is additionally necessary to improve the decoding efficiency. we suggests the creation of cardiac three-dimensional model and model of three-dimensional cardiac thickness as a new measurement. For the experiment, cardiac reduced cross section was obtained from SPECT. Next, the pre-process was performed and image segmentation was fulfilled by level set. for the modeling of left cardiac thickness, it was realized by applying difference equation of two-dimensional laplace equation. As the result of experiment, it was successful to measure internal wall and external wall and three-dimensional modeling was realized by coordinate. and, with laplace formula, it was successful to develop the thickness of cardiac wall. through the three-dimensional model, defects were observed easily and position of lesion was grasped rapidly by the revolution of model. The model which was developed as the support index of decoding will provide decoding information to doctor additionally and reduce the rate of false diagnosis as well as play a great role for diagnosing IHD early.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.327-331
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• 2011

Purpose: The purpose of this study was an accurate grasp of the astigmatic change due to eyes accommodation on near vision and suggested problems occurring accommodative astigmatism using near glasses. Methods: 154 subjects(308eyes) from 20 to 40 years selected for this study who had many opportunity of near vision. First, far vision corrective refraction measured using the phoropter, and then both eyes opened simultaneously for maintaining the function of binocular put away dot chart 40 cm. One eye was fogging and the other eye measured near vision astigmatism axis and degrees astigmatism using cross cylinder, and then compared with far astigmatism. Results: Increased degree of astigmatism persons on near vision more than decreased or did not changed degree of astigmatism persons, which could affect visual acuity more than 0.75 diopters in 30 eyes with an increase of 9.7% of total subjects. Direct astigmatism and oblique astigmatism were increased on near vision. Astigmatic axes were rotated base in direction on both eyes and 66.9% of subjects were more than ${\pm}$5$^{\circ}$ rotation. Due to the rotation axis of astigmatism, residual astigmatism is expected to occur and expect to adversely affect the eyes. Conclusions: Long-term using the glasses without correction of increased astigmatic and rotated axis on near vision should occur new residual astigmatism and increase the asthenopia also. Considered to be taken astigmatic change on near vision during near refraction examination.