• 한국해양학회지
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• v.25 no.2
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• pp.62-73
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• 1990

An experimental study is performed in order to catch the characteristics of the flow field at arrested salt wedge, using a rectangular open channel. Arrested salt wedge is generally so stable that the observations are easy, but velocities and interfacial waves are measured with the aid of visualization method, by injection of fluorescent dyes. The density interface, which is defined as the zone of maximum density variation with depth, exists in about 0.5 cm below the visual interface, and vertical density profile is quite well satisfied with Homeborn model. Interfacial layer has high turbulent intensity and its thickness decreases as the overall Richardson number increases and has magnitude of roughly 17% of upper layer. Cross-sectional velocity distribution just shows the influence of a side-wall friction and in the upper layer vertical velocity profile also becomes uniformly as Reynolds number increases, but in the lower layer it shows nearly parabolic type. Supposes that we divide salt wedge into three domains, that is, river mouth, intermediate and tip zone, entertainment coefficient is small at the intermediate zone and large at the river mouth and the tip zone. River mouth or intermediate zone has comparatively stable interface and capillary wave therefore s produced and propagated downstream. On the other hand, tip zone is very unstable, cusping ripple or bursting ripple is then produced incessantly. Arrested salt wedge form is nearly linear and has no relation to densimetric Froude number and Reynolds number.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.443-451
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• 1999

Objective: To examine the relationship between hypertension prevalence and the four commonest anthropometric measurements for obesity(body mass index(BMI), wasit-hip ratio(WHR), waist circumference(WC) and body fat in Korean adults. Methods: We studied the cross-sectional association of the anthropometric indices and blood pressure in 1,197 individuals(who were participants in the population-based cohort study). Hypertension was defined as blood pressure $\geq160/95\;mmHg$ or current use of antihypertensive medication. Informations on life-style factors were obtained from personal interview. Results: There were close associations between BMI, WHR and WC with blood pressure in both men and women. After age adjustment, BMI and WC showed significantly positive correlation with systolic and diastolic blood pressure levels in both men and women. Odds ratio(ORs) of being hypertensive were estimated comparing the highest to the lowest quantile, adjusting for age, smoking status, alcohol intake levels, education attainment. The simultaneously adjusted ORs of being hypertensive, comparing the highest vs the lowest categories, was for BMI 2.0(95% confidence interval(CI)=0.9-3.2) in men and 3.2 (95% CI=1.7-6.1) in women, for WC 2.1(95% CI=1.0-4.4) in men and 3.1 (95% CI=1.6-5.9) in women, for fat(%) 4.2(95% CI=1.9-9.5) in men and 2.1(95% CI=1.2-3.6) in women. Conclusion: In addition to measures of overall obesity(BMI) as well as central obesity(WHR, WC), body fat(%) was independently associated with prevalence of hypertension. Among obesity indices, body fat was the most predictor variable in hypertensive state in male and BMI was in female.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.499-504
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• 1999

Objectives : To evaluate whether a relation between blood lead and zinc proto porphyrin(ZPP) was modified by gender in Korean lead workers. Methods : A cross-sectional study was conducted with 1,304 male and 101 female subjects in 1997. The relation between blood lead and ZPP were evaluated with linear, exponential, and quadratic models. Then, the different effect of gender on the relation was examined by adding the interaction terms in the each model. Results : $Mean{\pm}SD$ of blood lead and ZPP level was different between male$(27.7{\pm}10{\mu}g/dl\;and\;51.3{\pm}23.4{\mu}g/dl)$ and female subjects$(22.5{\pm}9.2{\mu}g/dl\;and\;78.7{\pm}38.6{\mu}g/dl)$. After adjusting for possible confounders, the effect modification by gender was significant in linear$(\beta=1.119,\;p<0.001)$, exponential$(\beta=Exp(0.008),\;p<0.05)$, and quadratic model$(\beta=1.388,\;p<0.001)$. In separate analysis, a quadratic relation between blood lead and ZPP was shown in male lead workers$(\beta=0.036,\;p<0.001)$, but an exponential relation in female lead workers$(\beta=Exp(0.029), p<0.001)$. Conclusion : Our data showed that the increasing rate of ZPP in female were always higher than in male lead workers, suggesting that females were more susceptible to occupational lead exposure than males.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.780-790
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• 2020

In this study, the cell-wall microstructure and anti-swelling effectiveness (ASE) of heat-treated larch wood were evaluated and the correlation between them was analyzed. For this purpose, some larch lumbers were heat-treated for 12, 18, and 24 hours at temperatures of 190℃ and 220℃. By observing the scanning electron microscopy cross-sectional image of the heat-treated larch, it was confirmed that the shape of heat-treated wood cell changed, the cut-section of the wood cell wall was rough, and the intercellular space has become wide as the intercellular bonds had broken because of heat-treatment. In addition, the evaluation of the swelling for each treatment condition revealed that, as the heat-treatment temperature and duration increased, the amount of absorbed water and swelling decreased and the ASE increased. The decrease in the amount of absorbed water is thought to be affected by the chemical change in the cell wall by heat-treatment. On the contrary, the decrease in the swelling and the increase in the ASE are thought to be due to a combination of chemical changes and physical changes such as structural changes in the cell wall.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.81-89
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• 1994

Ti film of lOnm thickness and Co film of 18nm thickness were sequentially e-heam evaporated onto Si (100) substrates. Metal deposited samples were rapidly thermal-annt.aled(KTA) in thr N1 en vironment a t $900^{\circ}C$ for 20 sec. to induce the reversal of metal bilayer, so that $CoSi_{2}$ thin films could be formed. The sheet resistance measured by the 4-point probe was 3.9 $\Omega /\square$This valur was maintained with increase in annealing time upto 150 seconds, showing high thermal stab~lity. Thc XRII spectra idrn tified the silicide film formed on the Si substrate as a $CoSi_{2}$ epitaxial layer. The SKM microgr;iphs showed smooth surface, and the cross-sectional TKM pictures revealed that the layer formed on the Si substrate were composed of two Co-Ti-Si alloy layers and 70nm thick $CoSi_{2}$ epl-layer. The AES analysis indicated that the native oxide on Si subs~rate was removed by TI ar the beginning of the RTA, and Ihcn that Co diffused to clean surface of Si substrate so that epitaxial $CoSi_{2}$ film could bt, formed. In thc rasp of KTA at $700^{\circ}C$. 20sec. followed by $900^{\circ}C$, 20sec., the thin film showed lower sheet resistance, but rough surface and interface owing to $CoSi_{2}$ crystal growth. The application scheme of this $CoSi_{2}$ epilayer to VLSI devices and the thermodynarnic/kinetic mechan~sms of the $CoSi_{2}$ epi-layer formation through the reversal of Co/Ti bdayer were discussed.

• Nutrition Research and Practice
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• v.7 no.1
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• pp.43-48
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• 2013

Quantities as well as distributions of adipose tissue (AT) are significantly related to cardiovascular disease (CVD) risk factors and can be altered with caloric restriction. This study investigated which cross-sectional slice location of AT is most strongly correlated with changes in CVD risk factors after caloric restriction in obese Korean women. Thirty-three obese pre-menopausal Korean women ($32.4{\pm}8.5$ yrs, BMI $27.1{\pm}2.3\;kg/m^2$) participated in a 12 weeks caloric restriction program. Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) were measured using computed tomography (CT) scans at the sites of L2-L3, L3-L4, and L4-L5. Fasting serum levels of glucose, insulin, triglyceride, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), leptin and homeostasis model assessment-insulin resistance (HOMA-IR) were observed. Pearson's partial correlation coefficients were used to assess the relationship between AT measurement sites and changes in CVD risk factors after calorie restriction. When calories were reduced by 350 kcal/day for 12 weeks, body weight (-2.7%), body fat mass (-8.2%), and waist circumference (-5.8%) all decreased (P < 0.05). In addition, following caloric restriction, serum levels of glucose (-4.6%), TC (-6.2%), LDL-C (-5.3%), leptin (-17.6%) and HOMA-IR (-18.2%) decreased significantly (P < 0.05) as well. Changes in VAT at the level of L3-L4 were significantly greater than those at other abdominal sites, and these changes were correlated with changes in TC (P < 0.05), LDL-C (P < 0.001), SBP (P < 0.001) and HOMA-IR (P < 0.01). These results show that VAT at L3-L4 had a stronger correlation with CVD risk factors than with other AT measurement sites after caloric restriction.

• Clinical and Experimental Pediatrics
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• v.54 no.12
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• pp.501-506
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• 2011

Purpose: A high level of air pollutants can increase the number of patients with allergy-related diseases such as asthma and allergic rhinitis (AR). To analyze the association between air pollution and allergic disease, we investigated 2 areas in Korea: Incheon, an industrial area, and Jeju, a non-industrialized area. Methods: Second grade students at elementary schools (11 schools in Incheon and 45 schools in Jeju) were examined in a cross-sectional study. A questionnaire was used and a skin prick test was performed. The levels of $NO_2$, $CO_2$, $O_3$, particulate matter (PM) $PM_{10/2.5}$, formaldehyde, tVOCs, and dust mites in the classrooms and grounds were determined. Results: The levels of outdoor CO, $PM_{10}$, and $PM_{2.5}$ were significantly higher in Incheon (P<0.01). The levels of indoor CO, $CO_2$, $PM_{10}$, $PM_{2.5}$ were significantly higher in Incheon (P<0.01). The prevalence rates of AR symptoms at any time, AR symptoms during the last 12 months, diagnosis of rhinitis at any time, and AR treatment during the last 12 months were significantly higher in Incheon (P<0.01). The prevalence rate of wheezing or whistling at any time, and wheezing during the last 12 months were significantly higher in Incheon (P<0.01). Conclusion: We found that the children living in Incheon, which was more polluted than Jeju, had a higher rate of AR and asthma symptoms compared to children in Jeju. To determine the effect of air pollution on the development of the AR and asthma, further studies are needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1393-1401
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• 2010

In this experimental study, we have examined the correlation between a human carpal motion and a surface electromyogram. The carpal motion patterns have been identified and the main muscles involved in the carpal motion have been determined by investigating the anatomical structure of a carpal. The torque acting against the carpal motion has been applied by using a device for carpal rehabilitation training, and the surface electromyogram signal corresponding to the torque at the main muscles has been measured. The root-mean-square (RMS) magnitude of the surface electromyogram signal has been calculated and used to analyze the correlation between the surface electromyogram signal and carpal motion. The experimental results have proved that for carpal torque values below $0.1\;N{\cdot}m$, the RMS magnitude of the surface electromyogram signal is linearly proportional to the carpal torque magnitude and that the carpal torque magnitude is linearly proportional to the cross-sectional area of the carpal muscles. Further, the analysis of the contribution of each muscle to the carpal motion has shown that the contribution of the most dominant muscle is consistently 60%. These three results can be applied to develop more sophisticated devices or robots for carpal rehabilitation training.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.828-843
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• 1998

To find the association of perception of health status with lifestyle of different ethnic groups living in north-eastern part of China, a cross-sectional questionnaire survey was done by 10 local health workers for 375 Korean immigrants and 217 Chinese whose age was 30 years old or more. Because Korean immigrants showed higher mortality than Chinese, we expected to find significant lifestyle related with perception of health status which was known to be a predictor of mortality by different ethnic groups. The results were as follows : 1. We found that 59.7% of Yanbian Koreans and 42.9% of Yanbian Chinese felt unhealthy (p=0.000). 2. For Yanbian Koreans, significant variables associated with perception of health status were selected through logistic regression analysis and they were sex; female to male with an OR=2.45 (95% confidence interval[CI] 1.06, 5.64), prevalence of chronic illness with an OR=5.48 (95% CI: 4.62, 15.56), mont of meal; small or moderate to full with an OR=2.67 (95% CI : 1.40, 5.09), preference of spicy food with an OR=1.78 (95% CI : 1.04, 3.04), and less amount intake of vitamin $B_2$, with an OR=2.29 (95% CI : 1.33, 3.93). 3. For Yanbian Chinese, significant variables associated with perception of health status were prevalence of chronic illness with an OR=4.97 (95% CI : 2.11, 11.68), history of taking ginseng with an OR=3.72 (95% CI : 1.33, 10.43), and less intake of vitamin C with an OR=0.18 (95% CI : 0.07, 0.46). In conclusion, sex, presence of chronic illness, dietary habit, and amount of $vitamin-B_1$ intake were associated with perception of health status in Yanbian Koreans. Presence of chronic illness, experience of ginseng intake, and amount of vitamin C intake were associated with perception of health status in Yanbian Chinese. To prove cause-effect relation between perception of health status and lifestyle, further study is needed for these different ethnic groups.

• Journal of Preventive Medicine and Public Health
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• v.31 no.1 s.60
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• pp.59-71
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• 1998

To examine the association of hypertension with cluster of obesity, abnormal glucose and dyslipidemia in Korean urban population, we conducted this cross-sectional study among 3027 men and 2127 women age 20-85 years who visited a prevention center between May 1991 and June 1995 for a multiphasic health check at St. Mary's Hospital, Seoul. By the self-administered questionnaire, the informations of educational attainments, monthly income, alcohol consumption, cigarette smoking, and physical excercise level were obtained. Height, weight, and blood pressure were measured by a trained nurse. The fasting blood sugar (FBS), total cholesterol, high density lipoprotein (HDL) cholesterol and triglyceride were tested by enzyme method. Low density lipoprotein (LDL) cholesterol was calculated by 'total cholesterol - HDL cholesterol - triglyceride/5'. For testing the differences of cardiovascular risk factors between hypertension and normotension group, 1-test and $\chi^2$-test were performed. For the age adjusted odds ratios of hypertension in persons with obesity, abnormal glucose, and dyslipidemia compared with normal, logistic regression was performed by using SAS pakageprograme. The results obtained were as follows: 1. Age, weight, body mass index(BMI), blood glucose, total cholesterol, LDL cholesterol, and triglyceride of hypertension group in men and women were significantly higher than normotension group, but height and HDL cholesterol of hypertension group only in women significantly lower than normotension group. The frequency of obesity $(BMI\geq25kg/m^2)$, abnormal glucose $(\geq\;120mg/dl)$, hypercholesterolemia $(\geq\;240mg/dl)$, lower HDL cholesterol (<45 mg/dl in women only), higher LDL cholesterol $(\geq\;160mg/dl)$, and hyper hypertriglyceridemia $(\geq\;250mg/dl)$ in hypertension group of men and women were significantly higher than normotension group. 2. Systolic and diastolic blood pressure were negatively correlated with hight, but positively with age, weight, BMI, total cholesterol, LDL cholesterol, and triglyceride in men and women. BMI was positively correlated with fasting blood sugar, total cholesterol, LDL cholesterol and triglyceride but negatively with HDL cholesterol. 3. The age adjusted odds ratios of hypertension were as follows in men and women : among persons who were obese compared with those nonobese, 2.53 (95% Confidence Intervals [C.I.] 2.08-3.07) and 2.22 (95%C.I. 1.71-2.87): among persons who were abnormal glucose compared with those normoglycemic, 1.43 (95%C.I 1.13-1.82) and 2.01 (95%C.I 1.36-2.94): and among persons who were dyslipidemia (hypercholesterolemia or lower HDL cholesterol or higher LDL cholesterol or hypertriglyceridemia) compared with those normal lipid, 1.59 (95%C.I 1.30-1.95) and 1.51 (95%C.I 1.16-1.96). After combined more than one risk factor, the odds ratios were increased. Among persons with cluster of obesity, abnormal glucose, and dyslipidemia, the odds ratio of hypertension was 2.25 (95%C.I 1.47-3.37) in men and 3.02 (95%C.I 1.71-5.30) in women. In conclusion, it was suggested that hypertension was associated with cluster of obesity, abnormal glucose, dyslipidemia in this Korean urban population.