• Journal of the Korean Society of Food Culture
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• v.36 no.4
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• pp.349-361
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• 2021

This study was conducted to investigate the dietary adaptation and use of the university foodservice (UF) in Korea according to the residence period of foreign students. The average length of residence in Korea of t he subjects was 8.2 months. The period of residence was divided into quartiles: 1-4 months in the first quartile (average 2.2 months), 5-7 months in the second quartile (average 6.3 months), 8 months in the third quartile, and 9-66 months in the fourth quartile (average 18.3 months). The regularity of meals tended to be the highest in the 1st quartile and lowest in the 2nd quartile and then increased in the 3rd and 4th quartiles. The frequency of consumption of delivery food and convenience store food was lowest in the first quartile and highest in the second quartile and then decreased with the period of residence. The frequency of night eating increased according to the period of residence after the second quartile. The degree of adaptation to Korean foods was highest in the first quartile. The use of the university cafeteria was significantly higher in the 1st and 4th quartiles than in the 2nd and 3rd quartiles (p<0.05, p<0.01, respectively). The satisfaction with the UF decreased as the residence period increased. Based on these results, since international students are very positive and try to adapt to the dietary life in Korea in their early years of studying in Korea, it would be desirable to intensively support them to adjust to their dietary life at this time. In addition, since it takes about 18 months or more to assimilate the Korean food culture and show positive changes, it is necessary to continuously operate the Korean food culture adaptation program for international students over this period.

• Journal of dental hygiene science
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• v.17 no.3
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• pp.233-241
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• 2017

This study identified an effective control method for periodontitis by investigating the association between blood levels of vitamin D and periodontitis in Korean elderly based on raw data from the fifth Korea National Health & Nutrition Examination Survey of 2010 (KNHANES). In this study, 1,021 adults over 65 years of age were evaluated based on data from the KNHANES. Periodontal disease was assessed using community periodontal index (CPI), with CPI codes ${\geq}3$ defined as periodontitis. Blood levels of vitamin D were measured from blood samples and divided into four groups (first quartile: ${\leq}13.23ng/ml$, second quartile: 13.24~16.95 ng/ml, third quartile: 16.96~21.58 ng/ml), and fourth quartile >21.59 ng/ml). Using multiple logistic regression analyses, the variables were adjusted for general characteristics, oral health-related characteristics, health-related characteristics, and bone mineral density. The statistical analysis was performed using the SAS (ver. 9.2). The results of this study are as follows: the prevalence of periodontitis was 42.6% in Korean elderly. After adjusting for general, oral health-related, and health-related, the risk of periodontitis in the first quartile group was 1.74 times (95% confidence interval [CI], 1.02~2.98) higher than that of the fourth quartile group (p=0.041). After adjusting for general, oral health-related, and health-related characteristics as well as bone mineral density, the risk of periodontitis in the first quartile group was 1.73 times (95% CI, 1.02~2.96) higher than that of the four quartile group (p=0.042). There was a significant relationship between blood vitamin D level and periodontitis in Korean elderly. For the prevention of periodontitis, factors related to vitamin D should be considered along with other risk factors.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.1
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• pp.39-51
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• 1999

This study has an object to evaluate runoff characteristics with ILLUDAS model and SWMM owing to each rainfall distribution type of Huff's quartile and each rainfall duration time of 30 ,60, 120 and 180 minutes. As a result of this study, Type-Ⅰ Extreme (TIE) rainfall distribution pattern with Huff's 2nd quartile is adequate for Cheju volcanic island . To decide optimal rain fall duration , time of concentration and critical duration should be compared and analyzed each other. In this study, 30 and 120 miniutes were suggeste to iptiaml duration time of A and B study basins. It is concluded that the magnitude of peak runoff discharge is maximum with Huff's 4th quartile, and that of total runoff volume is maximum with Huff's 4th quartile for ILLUDAS model and with Huff's 1st quartile for SWMM. As rainfall duration time increasing is increasing . Also in case of total runoff volume, volumen by SWMM is less than by ILLUDAS model as to variation ratio of total runoff volume in A and B study basin. Therefore, the resulots of this study canb e sued as basic data in determining adequate rainfoal duration time and rainfall distribution type and used for urban drainage systems analysis and design at small urbanization catchment is Cheju volcanic island.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.150-155
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• 1998

It is necessary to describe a data set after collection of data in elementary statistics course. Two major numerical summary of the data set may be measures of central location and dispersion. There are various unmerical summary methods in presenting how data are dispersed and each method has its own advantages and disadvantages. Quartiles are discussed among several methods to describe dispersion of data set. When data type is discrete, exact quartile values are sometimes ambiguous to find, whereas exact quartile values are obtained for contionuous data. Examples of both data types are given. Programs listed below may be used to provide quartiles in MINITAB and SAS.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.39-46
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• 2005

We propose an equivariant and robust estimator in multivariate regression model based on the least quartile difference (LQD) estimator in univariate regression. We call this estimator as the multivariate least quartile difference (MLQD) estimator. The MLQD estimator considers correlations among response variables and it can be shown that the proposed estimator has the appropriate equivariance properties defined in multivariate regressions. The MLQD estimator has high breakdown point as does the univariate LQD estimator. We develop an algorithm for MLQD estimate. Simulations are performed to compare the efficiencies of MLQD estimate with coordinatewise LQD estimate and the multivariate least trimmed squares estimate.

• Preventive Nutrition and Food Science
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• v.19 no.4
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• pp.333-342
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• 2014

Limited epidemiologic data is available regarding the cardiovascular effects of mercury exposure. The purpose of this study was to determine the relationship between mercury exposure from fish consumption and cardiovascular disease in a nationally representative sample of Korean adults using the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV 2008~2009). Survey logistic regression models accounting for the complex sampling were used to estimate the odds ratios (OR) adjusted for fish consumption frequency, age, education, individual annual income, household annual income, body mass index (BMI), waist circumference (WC), alcohol consumption status, and smoking status. The mean blood mercury level in the population was $5.44{\mu}g/L$. Trends toward increased blood mercury levels were seen for increased education level (P=0.0011), BMI (P<0.0001), WC (P<0.0001), and fish (i.e., anchovy) consumption frequency (P=0.0007). The unadjusted OR for hypertension in the highest blood mercury quartile was 1.450 [95% confidential interval (CI): 1.106~1.901] times higher than that of the lowest quartile. The fish consumption-adjusted OR for hypertension in the highest blood mercury quartile was 1.550 (95% CI: 1.131~2.123) times higher than that of the lowest quartile, and the OR for myocardial infarction or angina in the highest blood mercury quartile was 3.334 (95% CI: 1.338~8.308) times higher than that of the lowest quartile. No associations were observed between blood mercury levels and stroke. These findings suggest that mercury in the blood may be associated with an increased risk of hypertension and myocardial infarction or angina in the general Korean population.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.2
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• pp.69-84
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• 1984

This study was carried out to investigate the time distribution of single storms and to establish the model of storm patterns in korea. Rainfall recording charts collected from 42 metheorological stations covering the Korean peninsula were analyzed. A single storm was defined as a rain period seperated from preceding and succeeding rainfall by 6 hours and more. Among the defined single storms, 1199 storms exceeding total rainfall of 80 mm were qualified for the study. Storm patterns were cklassified by quartile classification method and the relationship between cummulative percent of rainfalls and cummulative storm time was established for each quartile storm group. Time distribution models for each stations were prepared through the various analytical and inferential procedures. Obtained results are summarized as follows: 1. The percentile frequency of quartile storms for the first to the fourth quartile were 22.0%, 26.5%, 28.9% and 22.6%, respectively. The large variation of percentile frequency was show between the same quartile storms. The advanced type storm pattern was predominant in the west coastal type storm patterns predominantly when compared to the single storms with small total rainfalls. 3. The single storms with long storm durations tended to show delayed type storm patterns predominantly when compared to the single storms with short storm durations. 4. The percentile time distribution of quartile storms for 42 rin gaging stations was estimated. Large variations were observed between the percentiles of time distributions of different stations. 5. No significant differences were generally found between the time distribution of rainfalls with greater total rainfall and with less total rainfall. This fact suggests that the size of the total rainfall of single storms was not the main factor affecting the time distribution of heavy storms. 6. Also, no significant difference were found between the time distribution of rainfalls with long duration and with short duration. The fact indicates that the storm duration was no the main factor affecting the time distribution of heavy storms. 7. In Korea, among all single storms, 39.0% show 80 to 100mm of total rainfall which stands for the mode of the frequency distribution of total rainfalls. The median value of rainfalls for all single storms from the 42 stations was 108mm. The shape of the frequency distribution of total rainfalls showed right skewed features. No significant differences were shown in the shape of distribution histograms for total rainfall of quartile storms. The mode of rainfalls for the advanced type quartile storms was 80~100mm and their frequencies were 39~43% for respective quartiles. For the delayed type quartile storms, the mode was 80~100mm and their frequencies were 36!38%. 8. In Korea, 29% of all single storms show 720 to 1080 minutes of storm durations which was the highest frequency in the frequency distribution of storm durations. The median of the storm duration for all single storms form 42 stations was 1026 minutes. The shape of the frequency distribution was right skewed feature. For the advanced type storms, the higher frequency of occurrence was shown by the single storms with short durations, whereas for the delayed type quartile storms, the higher frequency was shown gy the long duration single storms. 9. The total rainfall of single storms was positively correlated to storm durations in all the stations throughout the nation. This fact was also true for most of the quartile storms. 10. The third order polynomial regression models were established for estimating the time distribution of quartile storms at different stations. The model test by relative error method resulted good agreements between estimated and observed values with the relative error of less than 0.10 in average.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.1
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• pp.22-29
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• 2016

Serum gamma-glutamyltransferase (GGT) has been widely used as a marker of alcohol intake and liver failure. Recently, the relativity between GGT and various diseases has been identified with growing interest. In this study, we examined relativity between GGT value and risk factors of coronary heart diseases among those with normal GGT value, excluding heavy drinkers. Specifically, we compared the differences based on age and gender. Data from the 2011 KNHNES were used (N=3,619). When the subjects were categorized according to quartile based on the serum GGT levels, there was 10~20, 21~27, 28~38, 39~71 IU/L in men, and 6~12, 13~16, 17~22, 23~42 IU/L in women. The mean of most variables was the highest in the $4^{th}$ quartile (Q4), however age and LDL Cholesterol were the highest in the $2^{nd}$ quartile (Q2) in men. The FRS and 10-year CHD risk was the highest in the $2^{nd}$ quartile in men, and the highest in the $4^{th}$ quartile in women. Increased GGT was correspondingly linked with age in women but age was the highest in GGT in the $2^{nd}$ quartile in men. In the 70's, the highest Q1 and Q2 was in men and the highest Q3 and Q4 in women. Although GGT value was within the normal range, increased GGT showed correlation with various risk factors. The FRS and 10-year CHD risk showed different patterns according to age and gender along with increased GGT value.

• Journal of Korean Medicine for Obesity Research
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• v.2 no.1
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• pp.25-36
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• 2002

Objective: The purposes of this study are to know the relations of abdominal obesity and ischemic stroke and to know what index could represent the abdominal obesity appropriately. Methods. We have done case-control study and recruited 97 ischemic stroke patients and 117 controls. Case is matched by control by individual matching. All participants had questionnaire, interview and then were examined waist-hip ratio, waist circumference and body mass index. Results : WC, WHR and Hypertension history had differences in two groups, case and control groups. But BMI and other factors weren't significant. According to Quartile of Waist Circumference, the two groups had the differences in hypertension history, diabetes history, smoking status, WHR, BMI, and weight and in the Quartile of Waist-Hip Ratio Quartile, past history of hypertension and diabetes, WC, BMI and weight had the significances. Sex, Age Adjusted and Multivariate Odds Ratio (95% Confidence Interval) of WC Quartile are 2.083, 1.628, 4.491 and 4.418, 4.964, 12.306, and in WHR, the Ors are 2.252, 5.743, 15.776 and 2.632, 8.918, 23.596. Conclusions: We knew from these results that abdominal obesity is very important risk factor of ischemic stroke and WHR more than WC is a good indicator of abdominal obesity, so we should reduce the WHR to prevent of ischemic stroke.

• Toxicological Research
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• v.30 no.1
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• pp.39-44
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• 2014

Bisphenol A (BPA) is widely used in the production of polycarbonate plastics, epoxy resins, and food and beverage containers. In the present study, we aimed to investigate the relationship between urinary concentrations of BPA and waist circumference in Korean adults. A total of 1,030 Korean adults (mean age, $44.3{\pm}14.6$ years) were enrolled in the study on the integrated exposure to hazardous materials for safety control, conducted by the Ministry of Food and Drug Safety from 2010 to 2012. Abdominal obesity was defined as having a waist circumference of at least 90 cm and 85 cm for men and women, respectively. The participants were divided into 4 groups according to the urinary BPA concentration quartile. Waist circumference was significantly higher among subjects with a urinary BPA concentration in the highest quartile relative to those in the lowest quartile (p = 0.0071). Linear regression analysis revealed a significant positive association between urinary BPA concentrations and body mass index, body fat, after adjusting for potential confounders. Moreover, subjects with urinary BPA concentrations in the fourth quartile were more likely to be obese compared to those with urinary BPA concentrations in the first quartile (odds ratio, 1.938; 95% CI: 1.314~2.857; p for trend = 0.0106). These findings provide evidence for a positive association between urinary BPA concentration and waist circumference in Korean adults.