• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.604-615
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• 1998

Although previous studies revealed the association of physical activity with mortality rate, it is unclear whether there is a linear trend between physical activity and mortality rate. In this study, the association of physical activity with the risk of all-cause mortality was analysed using Cox's proportional hazard model for a cohort of 14,204 healthy Korean men aged 40-59 years followed up for 4 years(Jan. 1993-Dec. 1996). Physical activity and other life style were surveyed by a postal questionnaire in December 1992. Total of 14,204 subjects were grouped into quartiles by physical activity. Using death certificate data, 123 deaths were identified. The second most active quartile had a lowest mortality .ate with relative risk of 0.44(95% C.I. : 0.23-0.84) compared with most sedentary quartile, showing a J-shape pattern of physical activity-mortality curve. By examining the difference in proportion of cause of the death between most active quartile and the other quartiles, there was no significant difference of proportional mortality from cardiovascular deaths, cerebrovascular deaths or deaths from trauma. The covariates were stratified into two group between which the trend of RR was compared to test the effect modification. There was no remarkable effect modification by alcohol intake, smoking, body mass index, calorie consumption, percent fat consumption. In conclusion, moderate activity was found to have more protective effect on all-cause mortality than vigorous activity and that the J-shape pattern of physical activity-mortality curve was not due to the difference of mortality pattern or effect modification by alcohol intake, smoking, body mass index, calorie consumption and percent fat consumption.

• Water for future
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• v.26 no.1
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• pp.115-124
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• 1993

This study is to determine the critical duration of design rainfall and to utilize it for the design of detention pond with pump station. To examine the effect of the duration and temporal distribution of the design rainfall, Huff's quartile method is used for the 9 cases of durations ranging from 20 to 240 minutes with 10 years return period, and the ILLUDAS model is used for runoff analysis. The storage ration which is the ratio of maximum storage amounts to total runoff volume, is introduced to determine the critical duration of design rainfall. The duration which maximizes the storage ratio is adopted as the critical duration. This study is applied to 18 urban drainage watersheds with pump station in Seoul, of which the range of watershed area is $0.24-12.70\textrm{km}^2.$ The result of simulation shows that the duration which maximizes storage ration is 30 and 60 minutes on the whole. It is shown also that the storage ration of 2nd- and 3rd-quartile pattern is larger than that of 1st- and 4th-quartile pattern of temporal distribution. A simplified empirical formula for Seoul area is suggested by using the regression analysis between the maximum storage ration and the peak ratio, and can be utilized for the preliminary design and planning of detention pond with pump station.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.249-258
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• 2020

Many climate studies have used the general circulation models (GCMs) for climate change, which can be currently available more than sixty GCMs as part of the Assessment Report (AR5). There are several types of uncertainty in climate studies using GCMs. Various studies are currently being conducted to reduce the uncertainty associated with GCMs, and the bias correction method used to reduce the difference between the simulated and the observed rainfall. Therefore, this study mainly considered climate change scenarios from nine GCMs, and then quantile mapping methods were applied to correct biases in climate change scenarios for each station during the historical period (1970-2005). Moreover, the monthly rainfall for the future period (2011-2100) is obtained from the RCP 4.5 scenario. Based on the bias-corrected rainfall, the standard deviation and the inter-quartile range (IQR) from the first to third quartiles were estimated. For 2071-2100, the uncertainty for the selection of GCMs is larger than that for the selection of bias correction methods and vice versa for 2011-2040. Therefore, this study showed that the selection of GCMs and the bias correction methods can affect the result for the future climate projection.

• Tuberculosis and Respiratory Diseases
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• v.68 no.2
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• pp.87-92
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• 2010

Background: D-dimer testing is widely applied as a first step in the diagnostic work-up of pulmonary embolism (PE). Although this is the most sensitive assay for ruling out PE, the prognostic implications of D-dimer testing in patients with normotensive PE are not well known. The aim of this study was to determine if D-dimer testing on admission predicts major adverse cardiac events (MACE) in patients with normotensive PE. Methods: A total of 180 consecutive patients with normotensive PE admitted between January 2003 and June 2009 were included. The group was divided into quartiles on the basis of their D-dimer levels. We compared the frequency of MACE by quartile of D-dimer level and estimated sensitivity, specificity, and predictive values for MACE in the first and fourth quartile. Results: In the 37 (20.6%) patients with MACEs, the median D-dimer level (7.94[IQR:4.03~18.17]${\mu}g/mL$) was higher than in patients with a benign course (5.29[IQR:2.60~11.52]${\mu}g/mL$, p<0.01). The occurrence of MACEs was increased with increasing D-dimer level (p=0.017). In the first quartile (D-Dimer <$2.76{\mu}g/mL$) sensitivity, specificity, and positive and negative predictive values for predicting MACEs were, respectively, 91.9%, 29.4%, 25.2%, and 93.3%. Conclusion: Patients with D-dimer levels below $2.76{\mu}g/mL$ have a low risk of MACEs. Our study suggest that D-dimer level may be used to identify low risk patients with normotensive PE.

• Korean Journal of Community Nutrition
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• v.18 no.1
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• pp.77-87
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• 2013

This study was conducted to investigate the nutrient intakes of subjects by quartile of percent energy intake from cooked rice, consumption of cooked rice mixed with multi-grains and to evaluate rice consumption in relation to the risk of metabolic syndrome. The subjects were 5,830 males and females aged between 20~64 years based on 2007-2008 KNHNES data. Levels of percent energy intake from cooked rice were classified into 4 groups (Q1, Q2, Q3, Q4 groups: 25% of each) using data of 24-hour recall method from KNHNES. Using medical examination and questionnaire, subjects were classified according to diagnostic criteria of metabolic syndrome. The subjects with higher age, being married, lower education, lower economic level were more likely to take higher percent energy intake from cooked rice. Quartile Q3 of percent energy intake from cooked rice tended to show higher Index of Nutritional Quality (INQ) for fiber, calcium, iron, potassium and vitamin A. INQ of protein, dietary fiber, calcium, thiamin, phosphorus, potassium, riboflavin, niacin and vitamin C by consumption of cooked rice mixed with multi-grains was higher than that by consumption of cooked white rice when adjusted for age. No association with a risk for metabolic syndrome was found for quartile of percent energy intake from cooked rice or cooked rice mixed with multi-grains compared to cooked white rice after adjusting for energy, gender, age, BMI, alcohol, smoking, income and physical activity. In conclusion, consumption of over 54% energy intake from cooked rice or only cooked white rice showed relatively low INQs, but was not associated with a higher risk for metabolic syndrome.

• Journal of Korea Spatial Information System Society
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• v.10 no.3
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• pp.55-65
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• 2008

For obtaining telematics traffic information(travel time or speed in an individual link), there are many kinds of devices to collect traffic data. Since the GPS satellite signals have been released to civil society, thank to the development of GPS technology, the GPS has become a very useful instrument for collecting traffic data. GPS can reduce the cost of installation and maintenance in contrast with existing traffic detectors which must be stationed on the ground. But. there are Problems when GPS data is applied to the existing filtering techniques used for analyzing the data collected by other detectors. This paper proposes a method to provide users with correct traffic information through filtering abnormal data caused by the unusual driving in collected data based on GPS. We have developed an algorithm that can be applied to real-time GPS data and create more reliable traffic information, by building patterns of past data and filtering abnormal data through selection of filtering areas using Quartile values. in order to verify the proposed algorithm, we experimented with actual traffic data that include probe cars equipped with a built-in GPS receiver which ran through Gangnam Street in Seoul. As a result of these experiments, it is shown that link travel speed data obtained from this algorithm is more accurate than those obtained by existing systems.

• Nutrition Research and Practice
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• v.16 no.1
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• pp.74-93
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• 2022

BACKGROUND/OBJECTIVES: There has been an increased interest in determining calcium magnesium, sodium, and potassium's distinct effects on hypertension over the past decade, yet they simultaneously regulate blood pressure. We aimed at examining the association of dietary calcium, magnesium, sodium, and potassium independently and jointly with hypertension using National Health and Nutrition Examination Survey data from 2007 to 2014. MATERIALS/METHODS: The associations were examined on a large cross-sectional study involving 16684 US adults aged>20 years, using multivariate analyses with logistical models. RESULTS: Sodium and calcium quartiles assessed alone were not associated with hypertension. Potassium was negatively associated with hypertension in the highest quartile, 0.64 (95% confidence interval [CI], 0.48-0.87). When jointly assessed using the high and low cut-off points, low sodium and corresponding high calcium, magnesium, and potassium intake somewhat reduced the odds of hypertension 0.39 (95% CI, 0.20-0.76). The sodium-to-potassium ratio was positively associated with hypertension in the highest quartile1.50 (95% CI, 1.11-2.02). When potassium was adjusted for sodium intake and sodium-to-potassium ratio assessed among women, increased odds of hypertension were reported in the highest quartile as 2.02 (95% CI, 1.18-3.34) and 1.69 (95% CI, 1.12-2.57), respectively. The association of combined minerals on hypertension using dietary goals established that men meeting the reference intakes for calcium and exceeding for magnesium had reduced odds of hypertension 0.51 (95% CI, 0.30-0.89). Women exceeding the recommendations for both calcium and magnesium had the lower reduced odds of 0.30 (95% CI, 0.10-0.69). CONCLUSIONS: Our results suggest that the studied minerals' association on hypertension is stronger when jointly assessed, mostly after gender stratification. As compared to men, women increased their risk of hypertension even with a low sodium intake. Women would also reasonably reduce their risk of developing hypertension by increasing calcium and magnesium intake. In comparison, men would somewhat be protected from developing hypertension with calcium intake meeting the dietary goals and magnesium exceeding the nutritional goals.

• Journal of the Korean Statistical Society
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• v.30 no.1
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• pp.63-76
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• 2001

An adaptive estimation and testing method is proposed for comparing dispersions among several ordered groups. Based upon the large sampling theory for nonparametric quartile estimators, we derive the order restricted estimators and construct a simple test statistic. This test statistic has a mixture of several chi-square distributions as its asymptotic null distribution. The proposed test is illustratively applied to survival time data for the patients with carcinoma of the oropharynx.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.401-410
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• 2009

Purpose : Pelvis and lumbar spine radiography, among various types of diagnostic radiography, include gonads of the human body and give patients high radiation dose. Nevertheless, diagnostic reference levels for patient radiation dose in pelvis and lumbar spine radiography has not yet been established in Korea. Therefore, the radiation dose that patients receive from pelvis and lumbar radiography is measured and the diagnostic reference level on patient radiation dose for the optimization of radiation protection of patients in pelvis and lumbar spine radiography was established. Methods : The conditions and diagnostic imaging information acquired during the time of the postero-anterior view of the pelvis and the postero-anterior and lateral view of the lumbar spine at 125 medical institutions throughout Korea are collected for analysis and the entrance surface dose received by patients is measured using a glass dosimeter. The diagnostic reference levels for patient radiation dose in pelvis and lumbar spine radiography to be recommended to the medical institutes is arranged by establishing the dose from the patient radiation dose that corresponds to the 3rd quartile values as the appropriate diagnostic reference level for patient radiation dose. Results : According to the results of the assessment of diagnostic imaging information acquired from pelvis and lumbar spine radiography and the measurement of patient entrance surface dose taken at the 125 medical institutes throughout Korea, the tube voltage ranged between 60~97 kVp, with the average use being 75 kVp, and the tube current ranged between 8~123 mAs, with the average use being 30 mAs. In the posteroanterior and lateral views of lumbar spine radiography, the tube voltage of each view ranged between 65~100 kVp (average use: 78 kVp) and 70~109 kVp (average use: 87 kVp), respectively, and the tube current of each view ranged between 10~100 mAs(average use: 35 mAs) and between 8.9~300 mAs(average use: 64 mAs), respectively. The measurements of entrance surface dose that patients receive during the pelvis and lumbar spine radiography show the following results: in the posteroanterior view of pelvis radiography, the minimum value is 0.59 mGy, the maximum value is 12.69 mGy and the average value is 2.88 mGy with the 1st quartile value being 1.91 mGy, the median being 0.59 mGy, and the 3rd quartile value being 3.43 mGy. Also, in the posteroanterior view of lumbar spine radiography, the minimum value is 0.64 mGy, the maximum value is 23.84 mGy, and the average value is 3.68 mGy with the 1st quartile value being 2.41 mGy, the median being 3.40 mGy, and the 3rd quartile value being 4.08 mGy. In the lateral view of lumbar spine radiography, the minimum value is 1.90 mGy, the maximum value is 45.42 mGy, and the average value is 10.08 mGy with the 1st quartile value being 6.03 mGy, the median being 9.09 mGy and the 3rd quartile value being 12.65 mGy. Conclusions : The diagnostic reference levels for patient radiation dose to be recommended to the medical institutes in Korea is 3.42 mGy for the posteroanterior view of pelvis radiography, 4.08 mGy for the posteroanterior view of lumbar spine radiography, and 12.65 mGy for the lateral view of lumbar spine radiography. Such values are all lower than the values recommended by 6 international organizations including World Health Organization, where the recommended values are 10 mGy for the posteroanterior view of pelvis radiography, 10 mGy for the posteroanterior view of lumbar spine radiography and 30 mGy for the lateral view of lumbar spine radiography.

• Journal of Nutrition and Health
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• v.38 no.2
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• pp.144-150
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• 2005

The aim of this study was to analyze an association between milk consumption and serum lipid profiles in postmenopausal women in Korea. The dietary data by the Food Frequency Questionnaire were evaluated among 208 postmenopausal women who did not receive hormone therapy and their serum concentrations of triglyceride (TG), total, HDL-, and LDL-cholesterol, and alkaline phosphatase were analyzed. When the relationship between milk consumption and serum lipid profiles were analysed by linear regression, we found a negative relationship of milk consumption with ALP and a positive relationship with HDL-cholesterol. Animal calcium intake was significantly correlated with ALP and HDL-cholesterol. In addition, the serum level of HDL-cholesterol of the upper quartile (UQ) subjects who took animal calcium over 313 mg/day was significantly higher than the lower quartile (LQ) subjects who consumed milk below 101 mg/day when we compared the UQ and LQ subjects. The HDL-cholesterol level of the UQ subjects who consumed 235 ml of milk tended to be higher than the that of the LQ who consumed 53 ml. As for serum concentrations of TG, total cholesterol, and LDL-cholesterol, there was no significant difference between the UQ and LQ groups of milk consumption. Based on our study, we concluded that continual consumption of approximately one cup of milk per day was associated with low cardiovascular risks with favorable lipid profiles and ALP in postmenopausal women. (Korean J Nutrition 38(2): 144～150, 2005)