• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.25-37
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• 2005

Objective : To estimate the magnitude of psychosocial distress and examine eligible factors associated with the development of psychosocial distress in Korean employees, using a nationwide sample. Methods : A total of 6,977 workers were recruited from 245 companies. A structured questionnaire was used to assess sociodemographics, health-related behaviors, job characteristics, social support at work, personality traits (locus of control, type A behavior pattern), self-esteem, and psychosocial distress. Results : The results showed that 23 % of workers were categorized as high stress, 73% as moderate, and 5% as normal. Hierarchical multiple regression analysis showed that psychosocial distress was more common in younger workers, both male and female. Regular exercise was negatively associated with increase of psychosocial distress. In job characteristics, as expected, low decision latitude, high job insecurity, and low social support at work were related to high psychosocial distress. Personality traits such as locus of control and type A behavior pattern, and self-esteem were more powerful predictors of psychosocial distress than general characteristics, health-related behavior, and job characteristics. There were some gender differences. While men who are less educated and single (unmarried, divorced, and separated) experienced higher levels of psychosocial distress than those who are educated and married, women who feel high job demand experienced higher levels of psychosocial distress than those who feel low job demand. Conclusions : The proportion of the high stress group was higher than expected, and psychosocial factors like social support and personality characteristics (e. g. locus of control, type A behavior pattern and self-esteem) were more significant factors for psychosocial distress than other variables. This finding suggests that some psychosocial factors, especially inadequate social support, low self-esteem and lack of internal locus of control for the development of psychosocial distress, will also operate as an intervention strategy in the worksite stress reduction program. It is strongly required that worksite stress reduction programs should be established in at both occupational and level as well as in individual levels.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.883-893
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• 2019

In this study, crop coefficients were calculated in two different methods and the results were evaluated. In the first method, appropriateness of GLDAS-based evapotranspiration was evaluated by comparing it with observed data of Cheongmi-cheon (CMC) Flux tower. Then, crop coefficient was calculated by dividing actual evapotranspiration with potential evapotranspiration that derived from GLDAS. In the second method, crop coefficient was determined by using MLR (Multiple Linear Regression) analysis with vegetation index (NDVI, EVI, LAI and SAVI) derived from MODIS and in-situ soil moisture data observed in CMC, In comparison of two crop coefficients over the entire period, for each crop coefficient GLDAS K_c and SM&VI K_c, shows the mean value of 0.412 and 0.378, the bias of 0.031 and -0.004, the RMSE of 0.092 and 0.069, and the Index of Agree (IOA) of 0.944 and 0.958. Overall, both methods showed similar patterns with observed evapotranspiration, but the SM&VI-based method showed better results. One step further, the statistical evaluation of GLDAS K_c and SM&VI K_c in specific period was performed according to the growth phase of the crop. The result shows that GLDAS K_c was better in the early and mid-phase of the crop growth, and SM&VI K_c was better in the latter phase. This result seems to be because of reduced accuracy of MODIS sensors due to yellow dust in spring and rain clouds in summer. If the observational accuracy of the MODIS sensor is improved in subsequent study, the accuracy of the SM&VI-based method will also be improved and this method will be applicable in determining the crop coefficient of unmeasured basin or predicting the crop coefficient of a certain area.

• Korean Journal of Remote Sensing
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• v.31 no.5
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• pp.441-448
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• 2015

Lack of agricultural information for food supply and demand in Democratic People's republic Korea(DPRK) make people sometimes confused for right and timely decision for policy support. We carried out a study to estimate paddy rice yield in DPRK using MODIS NDVI reflecting rice growth and climate data. Mean of MODIS $NDVI_{max}$ in paddy rice over the country acquired and processed from 2002 to 2014 and accumulated rainfall collected from 27 weather stations in September from 2002 to 2014 were used to estimated paddy rice yield in DPRK. Coefficient of determination of the multiple regression model was 0.44 and Root Mean Square Error(RMSE) was 0.27 ton/ha. Two-way analysis of variance resulted in 3.0983 of F ratio and 0.1008 of p value. Estimated milled rice yield showed the lowest value as 2.71 ton/ha in 2007, which was consistent with RDA rice yield statistics and the highest value as 3.54 ton/ha in 2006, which was not consistent with the statistics. Scatter plot of estimated rice yield and the rice yield statistics implied that estimated rice yield was higher when the rice yield statistics was less than 3.3 ton/ha and lower when the rice yield statistics was greater than 3.3 ton/ha. Limitation of rice yield model was due to lower quality of climate and statistics data, possible cloud contamination of time-series NDVI data, and crop mask for rice paddy, and coarse spatial resolution of MODIS satellite data. Selection of representative areas for paddy rice consisting of homogeneous pixels and utilization of satellite-based weather information can improve the input parameters for rice yield model in DPRK in the future.

• Journal of Chest Surgery
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• v.30 no.8
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• pp.760-769
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• 1997

This study aimed to determine factors that influence blood flow through coronary bypass grafts and to analyze relationship between the graft flow and postoperative outcome. Blood flow through 146 bypass grafts(GBF) was measured with transit-time ultrasound flowmeter during coronary artery bypass grafting operations in 50 patients. Single and multiple regression analyses were done for relationships between the GBF and four variables: internal diameter of recipient coronary artery, myocardial value of bypassed branch(es), type of graft, and finding of preoperative myocardial perfusion scan. The relationship between GBF and postoperative scan finding was also analyzed. 1. The mean GBF was significantly higher in sequential grafts than in single vein grafts or in internal thoracic artery grafts(61.5 vs. 46.9 and 42.5 ml/min). 2. Myocardial value and recipient artery diameter were found to be the factors determining GBF. There was no correlation between GHF and presence of perfusion defect in the preoperative scan. 3. Myocardial value was found to be more important than recipient artery diameter in determinintg GBF. 4. Reversible perfusion defects were more frequently found in the areas upplied by grafts with low GBP. But this fact had only mild statistical significance. These results suggest that blood flow through a bypass graft is more determined by the size of its supplyinf: myocardium than by the size of recipient artery. So, we can expect effective improvement in myocardial flow reserve after grafting of small(1~1.5mm) coronary arteries, if they supply substantial area of myocardium.

• Neonatal Medicine
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• v.16 no.2
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• pp.197-204
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• 2009

Purpose: The objective of this study was to describe the frequency of hepatobiliary dysfunction (HD) at our hospital and determine the possible risk factors and complications associated with the development of HD in very low birth weight infants (VLBWI) treated with parenteral nutrition (PN). Methods: A retrospective study of VLBWI (n=92) that required PN between 2004 and 2008 in the NICU at the Bucheon St. Marys Hospital of Catholic University was performed. HD was defined by a direct bilirubin (DB) >2 mg and a transaminase of 60 IU/L defined cholestasis and liver injury. Groups I, II, and III were limited to cases of cholestasis, liver injury without cholestasis, and no abnormalities, respectively. The VLBWI were compared to each other. Results: Thirty-six subjects (39.1%) had cholestasis and 51 (55.4%) had liver injury. In addition, 36 (39.1%), 19 (20.7%), and 37 (40.2%) subjects were classified as groups I, II, and III, respectively. The three groups showed significant differences in gestational age, 1- and 5-minute Apgar scores, use of surfactant, duration of parenteral nutrition, frequency of RBC transfusions, bronchopulmonary dysplasia (BPD), and patent ductus arteriosus (PDA) (P<0.05). The multiple regression analysis with cholestasis as the dependent variable, showed a significant correlation with gestational age, use of surfactant, frequency of RBC transfusions, and PDA. Conclusion: Various factors, such as birth weight, gestational age, 1- and 5-minute Apgar scores, use of surfactant for respiratory distress syndrome (RDS), frequency of RBC transfusions, BPD, and PDA may be related to hepatobiliary dysfunction in VLBWI treated with PN.

• Neonatal Medicine
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• v.17 no.1
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• pp.53-63
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• 2010

Purpose : Extrauterine growth restriction (EUGR) in preterm infants is a major problem in neonatal intensive care units (NICUs) and it has been related to long-term growth deficit and neurodevelopmental issues. The aim of this study was to investigate the frequency of and risk factors for EUGR. Methods : The study subjects consisted of very low birth weight (VLBW) infants with a gestational age $\leq$32 weeks that were born at the Seoul National University Children's Hospital between November 2005 and April 2009. EUGR was defined as weight for gestation, lower than the 10th percentile on discharge. Results : The frequency of EUGR was 67% (n=111/166). By multiple logistic regression, the presence of small for gestational age (SGA) was the greatest predictor of EUGR, birth weight and daily weight gain during the first 28 days were independent predictors of EUGR. Risk factors for EUGR in non-SGA infants were evaluated because 56% (64/114) of non-SGA infants developed EUGR at discharge. Daily weight gain in the first 28 days was also decreased in EUGR group and independently predicted the risk of EUGR in the non-SGA group. Conclusion : EUGR was a common problem in the NICU. SGA was the most significant predictive factor of the EUGR. Half of the non-SGA infants also developed EUGR, revealing poor weight gain in the early days was as an important predictor. These results support the importance of early nutritional intervention for weight gain which have lagged behind other modern therapeutic interventions when the infant is clinically unstable.

• Neonatal Medicine
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• v.17 no.1
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• pp.75-83
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• 2010

Purpose : This study was performed to determine the predictors of failed closure of a patent ductus arteriosus (PDA) following the first course of indomethacin in symptomatic preterm infants. Methods : Forty three of 43 preterm infants, admitted to the neonatal intensive care unit diagnosed with PDA and treated with indomethacin at the Korea University Medical Center between January 1990 and October 2007, ware studied. The perinatal risk factors affecting the failed closure of PDA were retrospectively assessed. Results : The failed PDA closure group included 16 (37%) out of 43 infants three of whom underwent surgery. The closure group included 27 (63%) out of 43 infants. In the failed closure group, the Apgar scores (1 min, 5 min) were significantly higher (P<0.05) and antenatal steroid administration was significantly lower (P<0.05). In addition, dopamine administration was significantly lower (P<0.05) and the mean postnatal age at diagnosis was significantly lower (P<0.05). Multiple logistic regression for the prediction of failed PDA closure found only antenatal steroid administration (OR 0.092, CI 0,010-0.826, P=0.0331) as an associated factor. Conclusion : In patients with antenatal steroid administration the failed PDA closure rate was significantly lower. Therefore, antenatal steroid administration can be considered as an important factor for the closure of PDA in preterm pregnancies.

• Journal of the Korean Society of School Health
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• v.10 no.2
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• pp.157-167
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• 1997

This study was conducted to investigate follow up tests and related factors in students who tested positive for in urine tests. For the purpose of this study, the authors analysed a self-administered questionnaire collected from 316 middle school students and 451 high school students who had positive urinalysis results in Kyungpook province during the month of February, 1996. The major findings of this study were as follows : The proportion of follow up tests among students was 39.2% in middle school students and 34.1% in high school students. There was a significant relation among a number of factors : parents' environment, health concern, and knowledge of urinalysis results, existence of nursing teachers, education concerning urinalysis, medical facility visits, and notification methods. In a multiple logistic regression analysis a higher economic level, parents' concern, knowledge of urinalysis results, medical facility visits, anti direct notification of parents were all significantly related with the follow up tests. On consideration of the above findings, in order to perform practical and effective follow-up management of students who have a positive result in urine test, direct notification of urine test result to parents as well as active health guidance in school are required.

• Journal of Biosystems Engineering
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• v.8 no.1
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• pp.9-16
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• 1983

This study was conducted to find out the effects of such parameters as specific draft resistance, slip rate, and fuel consumption rate on plowing performance in paddy fields spread with chopped rice straw. The plowing operation by an 8 P.S. power tiller was carried out in 6 different fields having the soil moisture content of 27~36 percent in dry basis in clay loam soil texture, and applying chopped rice straw of 10, 20, 30 and 60cm in length in the spring of 1982. The effects of soil hardness and moisture content on the plowing performance were also investigated. The results of the study are summarized as follows; 1. The minimum draft during the plowing operation was 110kg in the 30cm rice straw plot having the soil moisture content of 32 percent in dry basis. 2. The multiple regression equation of the specific draft(D) as a function of soil moisture content(M) and cutting length of rice straw(L) was obtained as follows. $D=14.1978-0.8565M+0.0661LxM-2.9685L+0.0133M^2+1.093L^2$ 3. In the 30cm rice straw plot with the soil moisture content of 32 percent in dry basis, the minimum specific draft resistance and the rate of slip were 0.35kg per $cm^2$ and 16 percent respectively. The specific draft resistance varied sensitively in accordance with the soil moisture content, and the slip rate of power tiller was dependent upon the cutting length of rice straw rather than the soil moisture content. 4. The highest plowing performance was 5.3 ares per hour at the soil moisture content of 35 percent and soil hardness of 10kg per $cm^2$. The relationship between the plowing performance and the soil moisture content was obtained by a quadratic equation. 5. The minimum fuel consumption rate in the plowing operation was recorded 6.5 liters per 10 ares in 30cm chopped rice straw plot with the soil moisture content of 32 percent in dry basis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2189-2198
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• 2012

This study was designed to measure the difference in health-related quality of life (HRQOL) among social classes and explore the factors that may explain it. Study subjects were 7,992 Korean adults aged 20-69 from the 4th (2007-2009) Korea National Health and Nutrition Examination Surveys data. We described mean value of EQ-5D index as a HRQOL by class and performed hierarchical multiple regression analysis to find the factors. The result was as follows. In the distribution of EQ-5D index level among social classes, new middle class (class II) had the highest score (0.966 in men and 0.955 in women); upper and middle-upper class (class I) 0.965 in men and 0.936 in women; working class (class IV) 0.958 in men and 0.936 in women; old middle class (class III) 0.955 in men and 0.932 in women; low class (class VI) 0.941 in men and 0.908 in women; and rural self-management class (class V) the lowest score (0.918 in men and 0.866 in women). In men, chronic disease, job stress, education and income level were found to make the difference in the health-related quality of life among social classes; in women, those factors and health behavior explained the difference. In conclusion, the lower social class has lower HRQOL. Except for education and income level, chronic disease may be the major factor to explain the difference in the health-related quality of life among social classes.