• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.316-331
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• 2019

Carbon dioxide($CO_2$) emission from rivers to the atmosphere is a key component in the global carbon cycle. Most of the rivers are supersaturated with $CO_2$. At a global scale, the amount of $CO_2$ emission from rivers is reported to be five-fold greater than that from lakes and reservoirs, but relevant data are rare in Korea. The objectives of this study is to estimate the $CO_2$ net atmospheric flux(NAF) from the upstream of Gangjeong-Goryeong Weir(GGW), Dalseong Weir(DSW), Hapcheon-Changnyeong Weir(HCW), and Changnyeong-Haman Weir(CHW) located in Nakdong River South Korea) using field and laboratory experiments and to apply data mining techniques to develop parsimonious prediction models that can be used to estimate $CO_2$ NAF with physical and water quality variables that can be collected easily. As a result, the study sites were all heterotrophic systems that often released $CO_2$ to the atmosphere, except when the algal photosynthesis was active.The median $CO_2$ NAF was minimum $391.5mg-CO_2/m^2$ day at GGW and maximum $1472.7mg-CO_2/m^2$ day at DSW. The $CO_2$ NAF showed a negative correlation with pH and Chl-a since the overgrowth of the algae consumed $CO_2$ in the water and increased the pH. As the parsimonious multiple regression model and random forest model developed, this study showed an excellent performance with the $Adj.R^2$ value higher than 0.77 in all weirs. Thus, these methods can be used to estimate $CO_2$ NAF in the river even if there is no $pCO_2$ measurement data.

• 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.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.731-745
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• 2021

In this study, the monthly temperature of the Han River basin was predicted by statistical multiple regression models that use global climate indices and weather data of the target region as predictors. The optimal predictors were selected through teleconnection analysis between the monthly temperature and the preceding patterns of each climate index, and forecast models capable of predicting up to 12 months in advance were constructed by combining the selected predictors and cross-validating the past period. Fore each target month, 1000 optimized models were derived and forecast ranges were presented. As a result of analyzing the predictability of monthly temperature from January 1992 to December 2020, PBIAS was -1.4 to -0.7%, RSR was 0.15 to 0.16, NSE was 0.98, and r was 0.99, indicating a high goodness-of-fit. The probability of each monthly observation being included in the forecast range was about 64.4% on average, and by month, the predictability was relatively high in September, December, February, and January, and low in April, August, and March. The predicted range and median were in good agreement with the observations, except for some periods when temperature was dramatically lower or higher than in normal years. The quantitative temperature forecast information derived from this study will be useful not only for forecasting changes in temperature in the future period (1 to 12 months in advance), but also in predicting changes in the hydro-ecological environment, including evapotranspiration highly correlated with temperature.

• Journal of Preventive Medicine and Public Health
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• v.43 no.2
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• pp.151-158
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• 2010

Objectives: The aim of this study was to evaluate the association between cigarette smoking and total mortality, cancer mortality and other disease mortalities in Korean adults. Methods: A total of 14 161 subjects of the Korean Multi-center Cancer Cohort who were over 40 years of age and who were cancer-free at baseline enrollment reported their lifestyle factors, including the smoking status. The median follow-up time was 6.6 years. During the follow-up period from 1993 to 2005, we identified 1159 cases of mortality, including 260 cancer mortality cases with a total of 91 987 person-years, by the national death certificate. Cox proportional hazard regression model was used to estimate the hazard ratio (HR) of cigarette smoking for total mortality, cancer mortality and disease-specific mortality, as adjusted for age, gender, the geographic area and year of enrollment, the alcohol consumption status, the education level and the body mass index (BMI). Results: Cigarette smoking was significantly associated with an increased risk of total mortality, all-cancer mortality and lung cancer mortality (p-trend, < 0.01, <0.01, <0.01, respectively). Compared to non-smoking, current smokers were at a higher risk for mortality [HR (95% CI)=1.3 (1.1 - 1.5) for total mortality; HR (95% CI)=1.6 (1.1 -2.2) for all-cancer mortality; HR (95% CI)=3.9 (1.9-7.7) for lung cancer mortality]. Conclusions: This study's results suggest that cigarette smoking might be associated with total mortality, all-cancer mortality and especially lung cancer mortality among Korean adults.

• Journal of Trauma and Injury
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• v.24 no.2
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• pp.89-94
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• 2011

Purpose: A few studies have assessed the factors affecting the prognoses for major trauma patients and those improving the circumstances when dealing with the trauma system. In that light, we analyzed factors, such as pre-hospital factors, the time to admission, the length of stay in the emergency department (ED) and emergency operation, influencing the outcomes for trauma patients. Methods: The patients who visited our emergency department from April 1, 2009, to February 29, 2011, due to major trauma were enrolled in the study. The inclusion criterion was a revised trauma score (RTS) < 7 or injury severity score (ISS) ${\geq}$ 16. We used reviews of medical records, to analyze each step of emergency medical care with respect to patients' sex, age, visit time and visit date. Continuous variables were described as a median with an interquartile range, and we compared the variables between the survival and the mortality groups by using the Mann-Whitney U test. Fisher's exact test was used for nominal variables. Using the variables that showed statistical significance in univariate comparisons, we performed a logistic regression analysis, and we tested the model's adequacy by the using the Hosmer-Lemeshow method. Results: A total of 261 patients with major trauma satisfied either the RTS score criterion or the ISS score criterion. Excluding 12 patients with missing data, 249 patients were included in this study. The overall mortality rate was 16.9%. Time to ED arrival, time to admission, time of ED stay, RTS, ISS, and visit date being a holiday showed statistically significant differences between the survival and the mortality groups in the univariate analysis. RTS, ISS, length of ED stay, and visit date being a holiday showed statistical significance in the multivariate analysis. Conclusion: The mortality rate did not show a significant relationship with the time to ED arrival, use of 119, on time to admission. Rather, it elicited a quite significant correlation with the trauma scoring system (RTS and ISS), the time of ED stay, and the visit date being a holiday.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2419-2423
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• 2015

Background: There are few choices for treatment of advanced cancer patients who do not respond to or tolerate conventional anti-cancer treatments. Therefore this study aimed to deploy the benefits and clinical efficacy of continuous dendritic cell-cytokine induced killer cell infusions in such patients. Materials and Methods: A total of 381 infusions (from 67 advanced cases recruited) were included in this study. All patients underwent peripheral blood mononuclear cell apheresis for the following cellular therapy and dendritic cells-cytokine induced killer cells were expanded in vitro. Peripheral blood T lymphocyte subsets were quantified through flow cytometry to address the cellular immunity status. Clinical efficacy and physical activities were evaluated by RECIST criteria and Eastern Cooperative Oncology Group scores respectively. Logistic regression model was used to estimate the association between cellular infusions and clinical benefits. Results: An average of $5.7{\pm}2.94{\times}10^9$ induced cells were infused each time and patients were exposed to 6 infusions. Cellular immunity was improved in that cytotoxic $CD8^+CD28^+$ T lymphocytes were increased by 74% and suppressive $CD8^+CD28^-$ T lymphocytes were elevated by 16% (p<0.05). Continuous infusion of dendritic cells-cytokine induced killer cells was associated with improvement of both patient status and cellular immunity. A median of six infusions were capable of reducing risk of progression by 70% (95%CI 0.10-0.91). Every elevation of one ECOG score corresponded to a 3.90-fold higher progression risk (p<0.05) and 1% increase of $CD8^+CD28^-$ T cell proportion reflecting a 5% higher risk of progression (p<0.05). Conclusions: In advanced cancer patients, continuous dendritic cell-cytokine induced killer cell infusions are capable of recovering cellular immunity, improving patient status and quality of life in those who are unresponsive to conventional cancer treatment.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6569-6573
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• 2015

Objective: To evaluate the application value of serum CA19-9, CEA, CA125 and CA242 in diagnosis and prognosis of pancreatic cancer cases treated with concurrent chemotherapy. Materials and Methods: 52 patients with pancreatic cancer, 40 with benign pancreatic diseases and 40 healthy people were selected. The electrochemiluminescence immunoassay method was used for detecting levels of CA19-9, CEA and CA125, and a CanAg CA242 enzyme linked immunoassay kit for assessing the level of CA242. The Kaplan-Meier method was used for analyzing the prognostic factors of patients with pancreatic cancer. The Cox proportional hazard model was applied for analyzing the hazard ratio (HR) and 95% confidential interval (CI) for survival time of patients with pancreatic cancer. Results: The levels of serum CA19-9, CEA, CA125 and CA242 in patients with pancreatic cancer were significantly higher than those in patients with benign pancreatic diseases and healthy people (P<0.001). The sensitivity of CA19-9 was the highest among these, followed by CA242, CA125 and CEA. The specificity of CA242 is the highest, followed by CA125, CEA and CA19-9. The sensitivity and specificity of joint detection of serum CA19-9, CEA, CA125and CA242 were 90.4% and 93.8%, obviously higher than single detection of those markers in diagnosis of pancreatic cancer. The median survival time of 52 patients with pancreatic cancer was 10 months (95% CI7.389~12.611).. Patients with the increasing level of serum CA19-9, CEA, CA125, CA242 had shorter survival times (P=0.047. 0.043, 0.0041, 0.029). COX regression analysis showed that CA19-9 was an independent prognostic factor for patients with pancreatic cancer (P=0.001, 95%CI 2.591~38.243). Conclusions: The detection of serum tumor markers (CA19.9, CEA, CA125 and CA242) is conducive to the early diagnosis of pancreatic cancer and joint detection of tumor markers helps improve the diagnostic efficiency. Moreover, CA19-9 is an independent prognostic factor for patients with pancreatic cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3879-3887
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• 2012

Background: Development of effective educational strategies should accompany increases in public awareness and the availability of genetic testing for breast cancer (BC). These educational strategies should be designed to fulfill the knowledge gap while considering factors that influence women's interest in order to facilitate decision making. Objective: To determine the possible correlates of Saudi women's interest in BC genes testing including socio-demographics, the level of awareness towards BC genes, the family history of BC and the perceived personal risk among adult Saudi women in Al Hassa, Saudi Arabia. Subjects and methods: This cross-sectional study was carried out during the second BC community-based campaign in Al Hassa, Saudi Arabia. All Saudi women aged ${\geq}18$ years (n=781) attending the educational components of the campaign were invited to a personal interview. Data collection included gathering information about sociodemographics, family history of BC, the perceived personal risk for BC, awareness and attitude towards BC genes and the women's interest in BC genes testing. Results: Of the included women (n=599), 19.5% perceived higher risk for BC development, significantly more among < 40 years of age, and with positive family history of BC before 50 years of age. The participants demonstrated a poor level of awareness regarding the inheritance, risk, and availability of BC genetic testing. The median summated knowledge score was 1.0 (out of 7 points) with a knowledge deficit of 87.8%. The level of knowledge showed significant decline with age (> 40 years). Of the included women 54.7% expressed an interest in BC genetic testing for assessing their BC risk. Multivariate regression model showed that being middle aged (Odds Ratio 'OR'=1.88, confidence intervals 'C.I'=1.14-3.11), with higher knowledge level (OR=1.67, C.I=1.08-2.57) and perceiving higher risk for BC (OR=2.11, C.I=1.61-2.76) were the significant positive correlates for Saudi women interest in BC genetic testing. Conclusion: Saudi women express high interest in genetic testing for BC risk despite their poor awareness. This great interest may reflect the presence of inappropriate information regarding BC genetic testing and its role in risk analysis.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3955-3960
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• 2012

Objective: To investigate the effects of $CD4^+$, IL17 and Foxp3 expression on prognosis of operable non-small cell lung cancer (NSCLC) with different pTNM stages. Methods: Expression of $CD4^+$, IL17 and Foxp3 in 102 cases of NSCLC tissues and adjacent cancer tissues was detected by immunohistochemistry and associations with prognosis with different pTNM stages were analyzed. The Chi-square test was used to compare count data. Survival differences were evaluated by Kaplan-Meier single factor analysis and the COX regression model was used to analyze the relationship between influential factors and the disease prognosis. The significance level was ${\alpha}$=0.05. Results: Expression of CD4, IL-17 and Foxp3 significantly varied in different pTNM stages of NSCLC tissues (P < 0.05). The same was true for CD4 expression (P < 0.05). The median survival time (MST) in the positive CD4 expression group was evidently higher than that in the negative group (25.8/23.9 months). Compared with stage III, the MST difference of stages I and II in the positive CD4 expression group were statistically significant (P < 0.05). The MST in positive IL-17 and Foxp3 expression groups was obviously lower than that in the corresponding negative group (P < 0.05) (25.6/35.1 months and 24/35.3 months, respectively). There was a significant difference of MST between any two of three stages of positive IL-17 expression group (P < 0.05), and it was the same with positive Foxp3 expression group. TNM stage, negative CD4 expression, and positive IL-17 and Foxp3 expression were the main risk factors for the prognosis of NSCLC. Conclusion: Surgical prognosis of NSCLC can be better assessed by the combination of clinical staging and expression of IL17 and Foxp3.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.829-844
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• 2013

This study performed comprehensive tests on the four hypotheses on the capital structures for the firms listed in the KOSPI during the period from 2006 to 2011. It may be of concern to find any financial profiles on firms' leverage across the book- and market-value bases since there was relatively little attention drawn to any financial changing profile of the leverage surrounding the period of the pre-and the post-global financial crises. The findings of this study may also be compared with those of the previous related literature, by which it may be expected to enhance the robustness and consistency of the results across the different classifications on capital markets. It was found that three explanatory variables such as PFT, SIZE, and RISK, were found to be the statistically significant attributes on leverage during the tested period. Moreover, the outcome by the Fisher Exact test showed that a firm belonging to each corresponding industry may possess its reversion tendency towards the industry mean and median leverage ratios.