• Management & Information Systems Review
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• v.39 no.2
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• pp.17-37
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• 2020

The purpose of this study is to investigate the global spillover effects through the existence of linear and nonlinear causal relationships between the US, European and BRIC financial markets after the period from the introduction of the Euro, the financial crisis and the subsequent EU debt crisis in 2007~2010. Although the global spillover effects of the financial crisis are well described, the nature of the volatility effects and the spread mechanisms between the US, Europe and BRIC stock markets have not been systematically examined. A stepwise filtering methodology was introduced to investigate the dynamic linear and nonlinear causality, which included a vector autoregressive regression model and a multivariate GARCH model. The sample in this paper includes the post-Euro period, and also includes the financial crisis and the Eurozone financial and sovereign crisis. The empirical results can have many implications for the efficiency of the BRIC stock market. These results not only affect the predictability of this market, but can also be useful in future research to quantify the process of financial integration in the market. The interdependence between the United States, Europe and the BRIC can reveal significant implications for financial market regulation, hedging and trading strategies. And the findings show that the BRIC has been integrated internationally since the sub-prime and financial crisis erupted in the United States, and the spillover effects have become more specific and remarkable. Furthermore, there is no consistent evidence supporting the decoupling phenomenon. Some nonlinear causality persists even after filtering during the investigation period. Although the tail distribution dependence and higher moments may be significant factors for the remaining interdependencies, this can be largely explained by the simple volatility spillover effects in nonlinear causality.

• Journal of Korean Medical Science
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• v.33 no.47
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• pp.303.1-303.10
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• 2018

Background: Cell division cycle 6 (CDC6) is an essential regulator of DNA replication and plays important roles in the activation and maintenance of the checkpoint mechanisms in the cell cycle. CDC6 has been associated with oncogenic activities in human cancers; however, the clinical significance of CDC6 in prostate cancer (PCa) remains unclear. Therefore, we investigated whether the CDC6 mRNA expression level is a diagnostic and prognostic marker in PCa. Methods: The study subjects included 121 PCa patients and 66 age-matched benign prostatic hyperplasia (BPH) patients. CDC6 expression was evaluated using real-time polymerase chain reaction and immunohistochemical (IH) staining, and then compared according to the clinicopathological characteristics of PCa. Results: CDC6 mRNA expression was significantly higher in PCa tissues than in BPH control tissues (P = 0.005). In addition, CDC6 expression was significantly higher in patients with elevated prostate-specific antigen (PSA) levels (> 20 ng/mL), a high Gleason score, and advanced stage than in those with low PSA levels, a low Gleason score, and earlier stage, respectively. Multivariate logistic regression analysis showed that high expression of CDC6 was significantly associated with advanced stage (${\geq}T3b$) (odds ratio [OR], 3.005; confidence interval [CI], 1.212-7.450; P = 0.018) and metastasis (OR, 4.192; CI, 1.079-16.286; P = 0.038). Intense IH staining for CDC6 was significantly associated with a high Gleason score and advanced tumor stage including lymph node metastasis stage (linear-by-linear association, P = 0.044 and P = 0.003, respectively). Conclusion: CDC6 expression is associated with aggressive clinicopathological characteristics in PCa. CDC6 may be a potential diagnostic and prognostic marker in PCa patients.

• Journal of Intelligence and Information Systems
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• v.23 no.3
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• pp.139-153
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• 2017

Corporate bankruptcy can cause great losses not only to stakeholders but also to many related sectors in society. Through the economic crises, bankruptcy have increased and bankruptcy prediction models have become more and more important. Therefore, corporate bankruptcy has been regarded as one of the major topics of research in business management. Also, many studies in the industry are in progress and important. Previous studies attempted to utilize various methodologies to improve the bankruptcy prediction accuracy and to resolve the overfitting problem, such as Multivariate Discriminant Analysis (MDA), Generalized Linear Model (GLM). These methods are based on statistics. Recently, researchers have used machine learning methodologies such as Support Vector Machine (SVM), Artificial Neural Network (ANN). Furthermore, fuzzy theory and genetic algorithms were used. Because of this change, many of bankruptcy models are developed. Also, performance has been improved. In general, the company's financial and accounting information will change over time. Likewise, the market situation also changes, so there are many difficulties in predicting bankruptcy only with information at a certain point in time. However, even though traditional research has problems that don't take into account the time effect, dynamic model has not been studied much. When we ignore the time effect, we get the biased results. So the static model may not be suitable for predicting bankruptcy. Thus, using the dynamic model, there is a possibility that bankruptcy prediction model is improved. In this paper, we propose RNN (Recurrent Neural Network) which is one of the deep learning methodologies. The RNN learns time series data and the performance is known to be good. Prior to experiment, we selected non-financial firms listed on the KOSPI, KOSDAQ and KONEX markets from 2010 to 2016 for the estimation of the bankruptcy prediction model and the comparison of forecasting performance. In order to prevent a mistake of predicting bankruptcy by using the financial information already reflected in the deterioration of the financial condition of the company, the financial information was collected with a lag of two years, and the default period was defined from January to December of the year. Then we defined the bankruptcy. The bankruptcy we defined is the abolition of the listing due to sluggish earnings. We confirmed abolition of the list at KIND that is corporate stock information website. Then we selected variables at previous papers. The first set of variables are Z-score variables. These variables have become traditional variables in predicting bankruptcy. The second set of variables are dynamic variable set. Finally we selected 240 normal companies and 226 bankrupt companies at the first variable set. Likewise, we selected 229 normal companies and 226 bankrupt companies at the second variable set. We created a model that reflects dynamic changes in time-series financial data and by comparing the suggested model with the analysis of existing bankruptcy predictive models, we found that the suggested model could help to improve the accuracy of bankruptcy predictions. We used financial data in KIS Value (Financial database) and selected Multivariate Discriminant Analysis (MDA), Generalized Linear Model called logistic regression (GLM), Support Vector Machine (SVM), Artificial Neural Network (ANN) model as benchmark. The result of the experiment proved that RNN's performance was better than comparative model. The accuracy of RNN was high in both sets of variables and the Area Under the Curve (AUC) value was also high. Also when we saw the hit-ratio table, the ratio of RNNs that predicted a poor company to be bankrupt was higher than that of other comparative models. However the limitation of this paper is that an overfitting problem occurs during RNN learning. But we expect to be able to solve the overfitting problem by selecting more learning data and appropriate variables. From these result, it is expected that this research will contribute to the development of a bankruptcy prediction by proposing a new dynamic model.

• Journal of agricultural medicine and community health
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• v.38 no.1
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• pp.14-24
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• 2013

Objectives: Pregnant women in rural areas do not have access to sufficient obstetric services in their own communities due to the shortage of obstetricians. Therefore, most of these women must seek obstetrician outside of their communities. The purpose of this study was to investigate the relationship between obstetric complications and accessibility to local obstetric care in Korea. Methods: This study was an ecological study in which the unit of analysis was an administrative district. Using Korea National Health Insurance Corporation data, the total number of deliveries and the delivery proportion within and outside of the community from 2001 to 2008 were calculated for 232 administrative districts nationwide. Three outflow levels were categorized based on each district's out-of-community delivery proportion: high outflow (upper one third), moderate outflow (middle one third), and low outflow (lower one third). In addition, three obstetric complication rates (the rate of complications following abortion, ectopic and molar pregnancy, the abortion rate, and the eclampsia rate) were calculated for the 232 districts. One-way ANOVA and multivariate linear regression were used to evaluate obstetric complications among the three outflow levels. Results: The high outflow districts had higher rates of eclampsia and complications following abortion, ectopic, and molar pregnancy compared to the other districts (ANOVA, p<0.05). However, there was no significant difference in the abortion rate among the three groups. Multiple linear regression analysis showed that high outflow districts were statistically significant in the rate of complications following abortion, ectopic and molar pregnancy and eclampsia rate after adjusting for local tax per capita (p<0.01). Conclusion: These results indicate that poor access to local obstetric care correlate with poor obstetric outcomes (delayed or excessive bleeding, embolism, genital tract or pelvic infection, shock or other complications following abortion and ectopic or molar pregnancy, or eclampsia).

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.1
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• pp.29-43
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• 2002

The purpose of this paper is to examine atmospherical factors affecting user's satisfaction in natural park to answer the research question: what are the effects of atmosphere on user's satisfaction in natural parks(NP). After reviewing the literature, mechanism of NP, and use elements in NP, We constructed the conceptual framework and have formulated the hypothesis of this research. We had obtained data through a questionnaire, which surveyed 508 visitors at 6 of the 73 NP in Korea in 2001, based on stratified sampling method. We have analyzed the data using descriptive statistical methods, the mean difference test, Pearson's correlation analysis, and the multiple linear regression method. We found that 1) the five atmospheric variables, j.e., number of users(NOU), crowding, damage to park resources(DPR), and maintenance of park resources and facilities(MPRF), encounter level(EL) affecting user's satisfaction, have tuned out to be statistically significant at a five percent level. The direction of the relationship between user's satisfaction and MPRF, NOU, EL is the same as that of the dependent variable and the opposite of crowding, and BPR, 2) in bivariate analysis, the positive relationships between user's satisfaction and park resources, MPRF are fairly high and statistically significant. The higher the value of DPR, and crowing, the lower the degree of user's satisfaction, 3) in multivariate analysis, such variables as NOU, crowding, DPR, EL, and MPRF affecting user's satisfaction have been statistically significant at five percent level, and 4) the relative contribution of MPRF, park resources, park facilities, NOU, crowding, DPR, and size of activity space on user's satisfaction have been determined to have respectively 6.00, 4.78, 2.53, 1.83, 1.64, 1.59 and 2.03 times more important than that of EL. Among the atmospheric variables, MPRF is the most important at 1.26 times higher than that of park resources. The research results suggest that the development of devices for the increase in user's satisfaction and user management program based on the knowledge we have found, be recommended in the planning and development process of natural park. The approach adopted by this research is valid and useful for evaluation criteria of NP. It is recommended that more empirical studies by activity types, activity spaces, and seasons on atmospheric elements affecting user's satisfaction be performed in the future.

• Biomedical Science Letters
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• v.18 no.2
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• pp.131-138
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• 2012

Autologous peripheral blood stem cell transplantation (PBSCT) has been used as a major treatment strategy for hematological malignancies. The number of CD34 positive cells in the harvested product is a very important factor for achieving successful transplantation. We studied the factors that can predict the number of CD34 positive cells in the harvested product of acute myelocytic leukemia (AML), multiple myeloma (MM) and Non-Hodgkin's lymphoma (NHL) patients after mobilizing them with chemotherapy plus G-CSF. A total of 73 patients (AML 19 patients, MM 28 patients, NHL 26 patients) with hematological malignancies had been mobilized with chemotherapy and granulocyte colony-stimulating growth factor from April, 2000 to February, 2012. Group's characteristics, checkup opinion of pre-peripheral blood on the day of harvest & outcome of PBSC were analyzed and evaluated using SPSS statistics program after grouping patients as below; group 1: CD34 cell counts < $2{\times}10^6/kg$ (n=16); group 2: $2{\times}10^6/kg{\leq}CD34$ cell counts < $6{\times}10^6/kg$ (n=32); group 3: CD34 cell counts ${\geq}6{\times}10^6/kg$ (n=25). We analyzed the clinical characteristics, the peripheral blood (PB) parameters and the number of CD34 positive cells in the PB and their correlation with the yield of CD34 positive cells collected from the mobilized patients. The total number of leukapheresis sessions was 263 (mean: 3.55 session per patient), and the mean number of harvested CD34 positive cells per patient was $7.37{\times}10^6/kg$. The number of CD34 positive cells in product was significantly correlated with the number of platelet and CD34 positive cells in peripheral blood (P<0.05). The number of PB CD34 positive cells was the best significant factor for the quantity of harvested CD34 positive cells on the linear regression analysis (P<0.05). Many factors could influence the mobilization of peripheral blood stem cells. Platelet count and PB CD34 positive cells count were the two variables which remained to be significant in multivariate analysis. Therefore, the number of platelet and CD34 positive cells in peripheral blood on the day of harvest can be used as an accurate predictor for successful peripheral blood stem cell collection.

• Journal of Nutrition and Health
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• v.53 no.2
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• pp.129-140
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• 2020

Purpose: Although the importance of life satisfaction in patients with chronic diseases has been emphasized, limited studies have been performed on the health-related quality of life (HRQoL) among elderly patients with chronic diseases. This study examined the HRQoL among Korean patients with diabetes aged 65 years or older. Methods: This study used data from the Korea National Health and Nutrition Examination Survey 2008-2016. The analysis included data of 2,353 elderly patients with diabetes aged 65 years or older who were aware that they had type 2 diabetes. Each participant was categorized into one of three age groups (65-69 years, 70-74 years, and ≥ 75 years). The EuroQol-5 Dimensions (EQ-5D) scale was computed to estimate the HRQoL. Multivariate linear regression analysis was used to compare the demographic characteristics, lifestyle characteristics, nutrient intake, and EQ-5D scores between the age groups. Results: The intake levels of most nutrients were similar in the three age groups, but the total energy intake levels were significantly lower, and the sodium intake levels were significantly higher in the older age groups (p < 0.001). In addition, all items of the EQ-5D index, except for anxiety/depression, tended to decrease with age. In particular, the oldest age group (≥ 75 years) showed significantly lower levels on most items and the EQ-5D index than those in the other age groups (p < 0.001). Conclusion: Elderly patients with type 2 diabetes may have low levels of life satisfaction, which worsens with increasing age. Therefore, it is important to develop and manage personalized guidelines and medical systems so that elderly patients have a higher quality of life for the remainder of their lives. The results of this study are expected to be used as basic data for the systematic management of diabetes in elderly Korean patients.

• Clinical and Experimental Pediatrics
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• v.57 no.12
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• pp.526-532
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• 2014

Purpose: Matrix metalloproteinases (MMPs) have been implicated in atherosclerosis, and therefore, are considered risk factors for metabolic dysfunction in adults. However, there is little data on circulating levels of MMPs and tissue inhibitors of MMPs (TIMPs) with regard to obesity-related biomarkers in the general adolescent population. In the present study, we determined the associations of MMP-8, MMP-9, and TIMP-1 levels and MMP-8/TIMP-1 and MMP-9/TIMP-1 ratios with obesity-related biomarkers in apparently healthy adolescent boys. Methods: We measured MMP and TIMP concentrations in plasma samples using the enzyme-linked immunosorbent assay and analyzed their associations with obesity-related biomarkers, such as liver enzymes and lipid profiles, in a sample of 91 Korean boys aged 13-14 years who participated in a general health check-up. Results: The mean age of the boys was $13.8{\pm}0.3years$; 72 boys were normal weight and 19 were overweight/obese. The Pearson correlation coefficients revealed a significant correlation between MMP-8 and aspartate aminotransferase (r=0.217, P=0.039) and alanine aminotransferase (r=0.250, P=0.017) and between TIMP-1 and aspartate aminotransferase (r=0.267, P=0.011). In a multivariate linear regression analysis, serum alanine aminotransferase was positively associated with the MMP-8 level. There were no significant differences in the MMP-8, MMP-9, and TIMP-1 levels or MMP-8/TIMP-1 and MMP-9/TIMP-1 ratios between control and overweight/obese subjects. Conclusion: We found a significant association between the MMP-8 level and alanine aminotransferase in the apparently healthy adolescent boys. These findings indicate that there may be a pathophysiological mechanism underlying the relationship between MMP-8 and liver enzymes in young adolescents.

• Environmental Analysis Health and Toxicology
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• v.28
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• pp.15.1-15.8
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• 2013

Objectives The aim of this study was to determine the association between low-level mercury exposure and neurobehavioral functions in adults living in coastal regions of Korea. Methods We selected 172 adults aged 20-65 years living in a city in the coastal region of Korea. A sociodemographic survey was conducted, mercury levels in the blood, urine, and hair were measured, and the associations according to computerized neurobehavioral tests were determined using univariate analysis. After adjustment for associated variables, a multivariate linear regression analysis was performed. Results The geometric mean mercury levels in the blood, urine, and hair were $5.41{\mu}g/L$ (range, $0.00-15.84{\mu}g/L$), $1.17{\mu}g/g$-creatinine (range, $0.00-32.86{\mu}g/g$-creatinine), and 1.37 mg/kg (range, 0.42-6.56 mg/kg), respectively. Variables that were associated with simple reaction time according to the neurobehavioral test results were age and urine mercury level. Variables associated with choice reaction time were the recent use of Korean traditional medicine and urine mercury level. Variables associated with the right-hand finger tapping speed test were age, gender, smoking behavior, education level, monthly household income, and urine mercury level. Variables associated with the left-hand finger tapping speed test were age, gender, education level, and urine mercury level. After adjustment for associated variables, there was no significant association between urine mercury level and simple reaction time (${\beta}=25.96$; p =0.47), choice reaction time (${\beta}=50.37$; p =0.32), or the number of left-hand finger taps (${\beta}=-1.54$; p =0.21). However, urine mercury level was significantly associated with the number of right-hand finger taps (${\beta}=-3.86$; p =0.01). Conclusions We found no evidence that low-level mercury exposure in adults is associated with deficits in neurobehavioral functions. A longer follow-up study is required to confirm this conclusion.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.397-402
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• 2014

Purpose: To investigate the relationship between axial length (AL) and anthropometric parameters in Korean children. Methods: This study included 40 urban school children aged 11-12 years (mean age, $11.95{\pm}0.22$ years; 45.0% girls) residing in Seoul, South Korea. AL (using partial coherence laser interferometry), corneal radius, refractive error, height (m), and weight (kg) were measured. Body mass index (BMI $[kg/m^2]=weight/[height]^2$) and degree of obesity (DO[%]=[actual weight standard weight]/standard weight) were calculated. Furthermore, the number of hours spent reading, watching television, and using a computer every day was determined using a detailed questionnaire. Results: The students had a mean spherical equivalent refraction of $1.06{\pm}0.84$ D. Weight (r=0.427, p=0.006), BMI (r=0.508, p=0.001), and DO (r=0.371, p=0.018) showed a significant positive correlation with AL. Furthermore, longer AL was significantly associated with heavier weight (p=0.041), and higher BMI (p=0.015), and higher DO quartiles (p=0.042). After adjust for age, sex, and near-work activities, multivariate linear regression models showed that weight, BMI, and DO were still significantly associated with AL. Among the near-work activities, daily reading time was significantly associated with AL. Conclusions: AL was positively related to weight as well as daily reading time in Korean urban school children.