• Journal of Environmental Impact Assessment
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• v.30 no.5
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• pp.271-296
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• 2021

Since the thermal stratification in a reservoir inhibits the vertical mixing of the upper and lower layers and causes the formation of a hypoxia layer and the enhancement of nutrients release from the sediment, changes in the stratification structure of the reservoir according to future climate change are very important in terms of water quality and aquatic ecology management. This study was aimed to develop a data-driven inflow water temperature prediction model for Daecheong Reservoir (DR), and to predict future inflow water temperature and the stratification structure of DR considering future climate scenarios of Representative Concentration Pathways (RCP). The random forest (RF)regression model (NSE 0.97, RMSE 1.86℃, MAPE 9.45%) developed to predict the inflow temperature of DR adequately reproduced the statistics and variability of the observed water temperature. Future meteorological data for each RCP scenario predicted by the regional climate model (HadGEM3-RA) was input into RF model to predict the inflow water temperature, and a three-dimensional hydrodynamic model (AEM3D) was used to predict the change in the future (2018~2037, 2038~2057, 2058~2077, 2078~2097) stratification structure of DR due to climate change. As a result, the rates of increase in air temperature and inflow water temperature was 0.14~0.48℃/10year and 0.21~0.41℃/10year,respectively. As a result of seasonal analysis, in all scenarios except spring and winter in the RCP 2.6, the increase in inflow water temperature was statistically significant, and the increase rate was higher as the carbon reduction effort was weaker. The increase rate of the surface water temperature of the reservoir was in the range of 0.04~0.38℃/10year, and the stratification period was gradually increased in all scenarios. In particular, when the RCP 8.5 scenario is applied, the number of stratification days is expected to increase by about 24 days. These results were consistent with the results of previous studies that climate change strengthens the stratification intensity of lakes and reservoirs and prolonged the stratification period, and suggested that prolonged water temperature stratification could cause changes in the aquatic ecosystem, such as spatial expansion of the low-oxygen layer, an increase in sediment nutrient release, and changed in the dominant species of algae in the water body.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.4
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• pp.41-54
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• 2021

This study targets the urban park corresponding to the core areas (Hubs) of Green Infrastructure and estimates their value utilizing the Contingent Valuation Method (CVM) and determines the planning factors which affect them. The research aims to provide basic data for supporting the value improvement in the planning stage for urban parks representing green infrastructure. The primary purpose of this research is to derive variables that affect economic value and planning factors to improve the use-value of urban parks, one of the Hubs of the green infrastructure. In this study, Sejong Lake Park, located in Sejong City, is the target site. This study collected the responses of 105 people by conducting a survey on the intention to pay for the use-value and the planning factors that affect it, targeting visitors to Sejong Lake Park. The study conducts Contingent Valuation Method (CVM) on this survey responses. The results are as follows: first, as a result of analyzing the variables which affect willingness to pay for use-value, residence and age influence the willingness to pay significantly among socioeconomic characteristics. Next, the survey responses of Double-bounded dichotomous choices (DB-DC) CVM are converted into variables through statistic techniques. Furthermore, the variables are used for a Logit model to draw coefficients. The average willingness to pay per person for the use-value of Sejong Lake Park using the derived coefficients was approximately found to be 8,597 won. Therefore, as of 2019, Sejong Lake Park, with a total of 430,000 visitors, is estimated to have an annual economic value of 3.7 billion won. Third, the average Likert scale of the planning factor affecting the decision to pay for the economic value of Sejong Lake Park was the highest along the waterfront landscape, and the convenience facilities and waterfront landscape showed the highest willingness to pay, 10,000 won. In the range between 2,500 won and 5,000 won, the waterfront area ranks highest. Therefore, it can be said that visitors to Sejong Lake Park take account of the economic value of using the waterfront landscape the most. This study is meaningful as a thesis on use-value and the planning factors that affected value evaluation results of urban parks, and the analysis of the correlation between the planning factors of urban parks as hubs located in urban areas.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.137-144
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• 2021

Purpose : The usability of X-Jaw split VMAT was evaluated by comparative analysis of the dose distribution between the treatment plan divided by X-Jaw and Full field VMAT treatment plan in left breast cancer treatment including supraclavicular lymph nodes. Materials and Methods : 10 patients with left breast cancer, including supraclavicular lymph nodes, were simulated using vacuum cushion, and 2 Full field Arc VMAT and 4 X-Jaw split Arc VMAT were planned The treatment plan was designed to include more than 95% of the Planning Target Volume (PTV) and to be minimally irradiated in the surrounding Organ at risk (OAR). Dose analysis of PTV and OAR was performed through dose volume histogram (DVH). Results : The Full field VMAT treatment plan and the X-Jaw split VMAT treatment plan of 10 patients were expressed as average values and compared. The difference between the two treatment plans was not large, with a Conformity index (CI) of 1.05±0.04, 1.04±0.03, and a Homogeneity index (HI) of 1.07±0.008, 1.07±0.009. For OAR, V5 in the left lung is 56.1±6.50%, 50.4±6.30%, and V20 is 20.0±4.15%, 13.52±3.61%. Compared to Full field VMAT, V5 decreased by 10.0% V20 by 32.6% in X-Jaw split VMAT. The V30 of the heart is 3.68±1.85%, 2.23±1.52%, and the Mean dose is 8.93±1.65 Gy, 7.67±1.52 Gy. In the X-Jaw split VMAT, V30 decreased by 39.3% and the Mean dose decreased by 14.1%. The left lung and heart, which are normal tissues, were found to have a statistical significance of that p-value is less than 0.05. Conclusion : In the case of left breast cancer treatment, which includes Supraclavicular lymph nodes with a large PTV volume and a length of X Jaw of 15 cm or more, the X-Jaw split VMAT shows improved dose distribution, which can reduce radiation dose of OAR such as lungs and heart, while maintaining similar PTV coverage with HI and CI equivalent to Full field VMAT. It is thought to be effective in reducing radiation complications.

• Journal of Industrial Convergence
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• v.21 no.3
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• pp.159-169
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• 2023

This study analyzed the factors affecting the opinions of life-sustaining treatment among the elderly in Korea. The study subjects were 10,097 people who responded to the survey on the condition of the elderly (2020), and using the SPSS 25.0 program, first, the demographic characteristics of the research subjects were identified through descriptive statistics and the average and normality of major variables were identified. Second, the chi-square was analyzed by conducting a cross-analysis of opinions on life-sustaining treatment according to the characteristics of the elderly. Third, a correlation analysis was performed to analyze the correlation between major variables. Fourth, the relative influence on the life-sustaining treatment of the elderly was identified through multiple regression analysis. The main research findings are as follows. First, 8,565 (84.8%) of the elderly were opposed to medical treatment (life-sustaining treatment) to save them even if they were unconscious or difficult to live. Second, as a result of cross-analysis on life-sustaining treatment for the elderly, the 𝑥² values of education level, health status, living together with children, and cost of living in old age were found to be significant. Third, the educational level of the elderly, living together with children, and the cost of living in old age were found to have statistically significant negative effects on life-sustaining treatment. Such research results indicate that the elderly with a high level of education oppose life-sustaining treatment compared to those with a low level of education. In addition, in the case of the elderly with traditional values who responded that one of their children should live with the elderly (parents), the ratio of people in favor of life-sustaining treatment was high, and in the case of the elderly with modern values who responded that they did not have to live together, the ratio of opposition to life-sustaining treatment was high. appeared to be high. In addition, in the case of the elderly with traditional values who responded that the burden of living expenses in old age should be shared between the state and society and their children, the proportion in favor of life-sustaining treatment was high. This high figure expressed the desire for well-dying. Based on these research results, the value system was re-examined as a factor influencing the elderly's opinion on life-sustaining treatment, and basic data for welfare policies for the elderly were provided.

• Radiation Oncology Journal
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• v.25 no.2
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• pp.70-78
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• 2007

[ $\underline{Purpose}$ ]: This study analyzed the tumor response, overall survival, progression free survival and related prognostic factors in patients with muscle invasive bladder cancer subjected to bladder preserving treatment. $\underline{Materials\;and\;Methods}$: Between August 1995 and June 2004, 37 patients with muscle invasive (transitional cell carcinoma, clinically stage T2-4) bladder cancer were enrolled for the treatment protocol of bladder preservation. There were 33 males and 4 females, and the median age was 67 years (range $38{\sim}86\;years$). Transurethral resection of the bladder (TURB) was performed in 17 patients who underwent complete resection. The median radiation dose administered was 64.8 Gy (range $55.8{\sim}67\;Gy$). The survival rate was calculated by the Kaplan-Meier method. $\underline{Results}$: An evaluation of the response rate was determined by abdomen-pelvic CT and cystoscopy at three months after radiotherapy. A complete response was seen in 17 patients (46%). The survival rate at three years was 54.7%, with 54 months of median survival (range $3{\sim}91$ months). During the study, 17 patients died and 13 patients had died from bladder cancer. The progression free survival rate at three years was 37.2%. There were 24 patients (64.9%) who had disease recurrence: 16 patients (43.2%) had local recurrence, 6 patients (16.2%) had a distant recurrence, and 2 patients (5.4%) had both a local and distant recurrence. The survival rate (p=0.0009) and progression free survival rates (p=0.001) were statistically significant when compared to the response rate after radiotherapy. $\underline{Conclusion}$: The availability of complete TURB and appropriate chemoradiotherapy were important predictors for bladder preservation and survival.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.43-60
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• 1968

In order to find the effects of nitrogen type (ammonium sulfate and urea fertilizer) and fertilized depth, (0~10cm, 0cm, 5~10cm, 10~15cm, 15~20cm, and 20cm below) on leaching and absorption of nitrogen in paddy soil, and growth and yields of rice, the pot culture experiment was carried out, using the variety Jaekun, one of the Korean leading variety. Experimental results were Summarized as follows: 1. No variations of the pH of percolating water were induced by the differences of nitrogen types and their fertilized depth (Table. 2). 2. The leaching of nitrogen was less in ammonium sulfate and top soil fertilizing plots than in urea and subsoil fertilizing plot, and the growth of rice in early stage was more promoted in ammonium sulfate and topsoil fertilizing plots (Table. 1, 7 and 8). 3. Leachng of nitrogen through the percolating water almost came to an end at the most numerous tiller stage (Table 1). 4. The absorption of nitrogen of each part of the rice plant in the harvesting stage correlated closely with the yields of each part (Table 5, 6, 9 and 10) and the leaching of nitrogen in the early stage was inversely proportion to the absorption of nitrogen of rice plant in the harvesting time (Table 1, 5, 6, 9 and 10). 5. The number of spikes was more numerous in ammonium sulfate plots than in urea plots on an average, so that the yields were higher in the ammonium sulfate plots than in urea plots although no differences in the grain number per spike were found in above two plots. The number of spikes was more numerous in topsoil fertilizing plots than in subsoil fertilizing plots, but the grain number per spike was less in former than in latter, so that no difference in yields was found. The absorption of nitrogen correlated closely with the yields in complete paddy grains (Table 5, 9, and 10). 6. At the ammonium sulfate fertilizing plots, the number of spikes was more numerous in topsoil fertilizing plots than in subsoil fertilizing plots, (among the each of the topsoil plots, 0~10cm and 5~10cm fertilizing plots kept more spikes than the 0cm fertilizing plots), but the grain number per spike was less in former than in latter (among the each of topsoil plots, no differences were found), so that no significant difference in yields was showed between the topsoil and subsoil fertilizing plots, but the results showed the tendency that the yields were highest in 0~10cm plots and the lowest in 20cm below plots. At the urea fertilizing plots, the number of spikes decreased in proportion to the increasing of fertilized depth, but no variations were found in the grain number per spike, so that the yields decreased in proportion to the increasing of fertilized depth. The absorption of nitrogen correlated closely with the yields in complete paddy grains (Table 5, 6, 9, and 10). 7. When fertilized in topsoil, the number of spikes was more numerous in ammonium sulfate plot than in urea plot, but the grain number per spike variated reversely, so that no differences were found in the yields between the ammonium sulfate and the urea plots, when fertilized in subsoil, both the number of spikes and the grain number per spike were larger in ammonium sulfate than in urea plot, so that the yields were also higher in ammonium sulfate plots (Table 5, 6, 9 and 10). 8. The weight of straw and its nitrogen absorption were higher in ammonium sulfate plot than in urea plot and decreased in proportion to the increasing of fertilized depth. Among the each of topsoil fertilizing plots, the 0~10cm and the 5~10cm fertilizing plots excelled the 0cm plot (Table 5, 6, 9 and 10). 9. No significant variations in the fertilizer treatments were found in the characters of heading date, maturing date, length of culm, length of spike, weight of empty grain, 1,000 grain weight, and one liter weight.