• Title/Summary/Keyword: Model Based

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A Study of Decision-making Support Method based on System Dynamics for Reservoir Risk Judgment (시스템 다이내믹스 기반의 저수지 위험판단 의사결정지원 방안 연구)

  • Duckgil Kim;Jiseong You;Hayoung Jang;Daewon Jang
    • Journal of Wetlands Research
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    • v.26 no.3
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    • pp.279-284
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    • 2024
  • Recently, the frequency and intensity of torential rains caused by climate change are increasing, and the damage to reservoir collapse in local governments continues to occur. Most local government reservoirs are aged reservoirs that have been built for more than 50 years, and there is a high risk of collapse due to recent heavy rainfall. In order to prevent reservoir collapse or overflow caused by heavy rainfall, a decision-making support system that can judge risks due to changes in storage capacity is needed. In this study, a reservoir discharge simulation model was constructed using a system dynamics technique that can dynamically represent causal relationships between various variables. Through discharge simulation, the change in storage capacity due to rainfall was analyzed, and the operation time and termination time of the discharge facility to prevent overflow of the reservoir were analyzed. Using the results of this study, it is possible to determine the timing of the overflow of the reservoir due to torrential rain, and also the capacity and operation timing of the discharge facility to prevent overflow can be known. hrough this, it is expected that local governments will be able to judge the risk of damage to reservoirs and establish a preliminary response plan to prevent damage.

The Study on the Application for Christian Education by Moed, Jewish Mishnah (유대교 미쉬나 모에드(Moed)의 기독교교육을 위한 적용방안)

  • Jang-Heum Ok
    • Journal of Christian Education in Korea
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    • v.75
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    • pp.33-56
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    • 2023
  • Purpose of study: The purpose of this study is to analyze the origins and texts of the Jewish scriptures, the Mishnah Moed, and to examine them from the perspective of educational theology to suggest practical application methods for Christian education. Research content and method: In order to achieve the purpose of the research, the contents were set as follows. First, for analyzing the origin and text of Mishnah Moed, the historical process until Mishnah Moed was edited was reviewed, and the contents of the text of Mishnah Moed were classified into 2 groups of 12 Masekkot from the viewpoint of the researcher; The first group is the contents Shabbath and Festivals : Shabbat, Pesahim, Yoma, Sukkah, Rosh haShanah, Megillah and the other group is as a rule to keep the festival, Erubin, Sheqalim, Betzah, Taanith, Moed Qatan, Hagigah. Second, in order to analyze the mishnah moed in educational theology, the church calendar for the festivals currently used in Christianity was analyzed by dividing it into the origin of the church year, the contents of the church year, and the scriptures of the church year. Third, as an educational model for applying Mishnah Moed to Christian education, the goal of seasonal education, the content of seasonal education, and the method of seasonal education were presented. Conclusions and Suggestions: The conclusion of the research is as follows; First, seasonal education based on the teachings of the Bible must be conducted within the Christian community. Second, The education is needed for leading a life that correctly understands and practices the historical process of the Christian festivals. Third, various church education programs should be developed and utilized according to the Christian Bible routine. Fourth, numerous symbols symbolizing the Christian festivals must be created and educated. Fifth, except for the festivals of the sufferings of Jesus Christ, the rest of the festivals must be observed as Celebration.

Smoking-attributable Mortality in Korea, 2020: A Meta-analysis of 4 Databases

  • Eunsil Cheon;Yeun Soo Yang;Suyoung Jo;Jieun Hwang;Keum Ji Jung;Sunmi Lee;Seong Yong Park;Kyoungin Na;Soyeon Kim;Sun Ha Jee;Sung-il Cho
    • Journal of Preventive Medicine and Public Health
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    • v.57 no.4
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    • pp.327-338
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    • 2024
  • Objectives: Estimating the number of deaths caused by smoking is crucial for developing and evaluating tobacco control and smoking cessation policies. This study aimed to determine smoking-attributable mortality (SAM) in Korea in 2020. Methods: Four large-scale cohorts from Korea were analyzed. A Cox proportional-hazards model was used to determine the hazard ratios (HRs) of smoking-related death. By conducting a meta-analysis of these HRs, the pooled HRs of smoking-related death for 41 diseases were estimated. Population-attributable fractions (PAFs) were calculated based on the smoking prevalence for 1995 in conjunction with the pooled HRs. Subsequently, SAM was derived using the PAF and the number of deaths recorded for each disease in 2020. Results: The pooled HR for all-cause mortality attributable to smoking was 1.73 for current men smokers (95% confidence interval [CI], 1.53 to 1.95) and 1.63 for current women smokers (95% CI, 1.37 to 1.94). Smoking accounted for 33.2% of all-cause deaths in men and 4.6% in women. Additionally, it was a factor in 71.8% of men lung cancer deaths and 11.9% of women lung cancer deaths. In 2020, smoking was responsible for 53 930 men deaths and 6283 women deaths, totaling 60 213 deaths. Conclusions: Cigarette smoking was responsible for a significant number of deaths in Korea in 2020. Monitoring the impact and societal burden of smoking is essential for effective tobacco control and harm prevention policies.

A Study on Customer Experience with Food Truck Services: Focusing on Topic Modeling Techniques (푸드트럭 서비스 이용객 경험에 관한 연구: 토픽모델링 기법 중심으로)

  • Jooa Baek;Yeongbae Choe
    • Journal of Service Research and Studies
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    • v.14 no.3
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    • pp.188-205
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    • 2024
  • The food truck business, which involves selling various types of food from mobile vehicles, has gained significant popularity in urban centers and at events. These food trucks have rapidly expanded due to their relatively low initial investment and high flexibility, attracting customers with unique menus and personalized services. However, as competition increases, the need to manage service quality to boost customer satisfaction and encourage repeat visits has become more critical. Despite this growing importance, there has been limited empirical research on the topic. This study aims to analyze customer experiences with food truck services to gain strategic insights for improving service quality. By applying structural topic modeling to customer review data, the study identified 50 key topics. The process included a comprehensive evaluation of model diagnostics and interpretability to determine the optimal number of topics, ultimately selecting the most relevant ones related to service experiences. The impact of these identified topics on overall customer satisfaction was empirically tested using regression analysis. The results showed that aspects such as "Food Taste," "Friendly Staff," and "Positive Emotion" had a positive influence on customer satisfaction, whereas "Delayed Service," "Negative Emotion," and "Beverage Service" had a negative impact. Based on this analysis, the study proposes concrete methods for food truck operators to systematically analyze customer feedback and use it to drive service improvements and innovation. This research highlights the importance of data-driven decision-making in small business environments like food trucks and contributes to expanding the application of topic modeling in the service industry.

Predicting 30-day mortality in severely injured elderly patients with trauma in Korea using machine learning algorithms: a retrospective study

  • Jonghee Han;Su Young Yoon;Junepill Seok;Jin Young Lee;Jin Suk Lee;Jin Bong Ye;Younghoon Sul;Se Heon Kim;Hong Rye Kim
    • Journal of Trauma and Injury
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    • v.37 no.3
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    • pp.201-208
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    • 2024
  • Purpose: The number of elderly patients with trauma is increasing; therefore, precise models are necessary to estimate the mortality risk of elderly patients with trauma for informed clinical decision-making. This study aimed to develop machine learning based predictive models that predict 30-day mortality in severely injured elderly patients with trauma and to compare the predictive performance of various machine learning models. Methods: This study targeted patients aged ≥65 years with an Injury Severity Score of ≥15 who visited the regional trauma center at Chungbuk National University Hospital between 2016 and 2022. Four machine learning models-logistic regression, decision tree, random forest, and eXtreme Gradient Boosting (XGBoost)-were developed to predict 30-day mortality. The models' performance was compared using metrics such as area under the receiver operating characteristic curve (AUC), accuracy, precision, recall, specificity, F1 score, as well as Shapley Additive Explanations (SHAP) values and learning curves. Results: The performance evaluation of the machine learning models for predicting mortality in severely injured elderly patients with trauma showed AUC values for logistic regression, decision tree, random forest, and XGBoost of 0.938, 0.863, 0.919, and 0.934, respectively. Among the four models, XGBoost demonstrated superior accuracy, precision, recall, specificity, and F1 score of 0.91, 0.72, 0.86, 0.92, and 0.78, respectively. Analysis of important features of XGBoost using SHAP revealed associations such as a high Glasgow Coma Scale negatively impacting mortality probability, while higher counts of transfused red blood cells were positively correlated with mortality probability. The learning curves indicated increased generalization and robustness as training examples increased. Conclusions: We showed that machine learning models, especially XGBoost, can be used to predict 30-day mortality in severely injured elderly patients with trauma. Prognostic tools utilizing these models are helpful for physicians to evaluate the risk of mortality in elderly patients with severe trauma.

Derivation of On-site Major Exposure Factor using NDD Analysis when Landfilling NORM Waste (NORM 폐기물 매립 시 NDD 분석을 활용한 부지 내 주요 피폭인자 도출)

  • Ji Hyeon Lim;Shin Dong Lee;Geon Woo Son;Kwang Pyo Kim
    • Journal of Radiation Industry
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    • v.18 no.3
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    • pp.183-193
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    • 2024
  • As part of the social response to the radon bed incident in 2018, the Nuclear Safety and Security Commission took measures to collect and dispose of all radon beds. The Waste Management Act provides landfill disposal as one of the disposal methods for natural radioactive product waste, which is one of the NORM wastes. When NORM wastes are landfilled, workers and the public at the landfill site are exposed to radiation through various pathways, such as leaching of radionuclides through soil and groundwater, and multiple exposure factors are involved simultaneously. In order to improve the reliability of radiological impact assessment, the values of main exposure factors should be selected more accurately. Therefore, before developing the main exposure factors for site characteristics, it is necessary to prioritize main exposure factors reflecting domestic characteristics of NORM waste landfills. Therefore, in this study, the main exposure factors for NORM waste landfill were derived using NDD analysis. To derive the main exposure factors, the analysis tool was first selected as RESRAD-ONSITE computer code, and the exposure scenarios were mainly selected as a resident farmer and suburban resident scenario, recreation scenario, and industrial worker scenario. Then, the priority 1 and 2 factors were selected for sensitivity analysis, and a Korean standard model was established to reflect Korean characteristics. Finally, the sensitivity analysis was conducted through NDD, and the main exposure factors were derived based on this. In the resident farmer scenario, the contaminated zone distribution coefficients of 226Ra, 210Pb, 232Th, 228Ra, 234U, and 238U, as well as precipitation and evapotranspiration factors, were derived as the main exposure factors. In the suburban resident scenario, the contaminated zone distribution coefficients of 226Ra, 210Pb, 232Th, 228Ra, 234U, and 238U, as well as precipitation and evapotranspiration coefficients, were derived as the main exposure factors. In the recreation scenario, the contaminated zone distribution coefficient of 232Th was derived as the main exposure factor. For the industrial worker scenario, the erosion rate was derived as the main exposure factor. The main exposure factors for each scenario were analyzed to be different depending on the scenario characteristics. The results of this study can be utilized as a basis for radiological environmental impact assessment of NORM waste landfill in Korea.

Effects of the teacher characteristics on self-directed learning mediated by students' class attitude and class satisfaction in mathematics (수학 교과에서 교사특성이 수업태도와 수업만족도를 매개로 고등학생의 자기주도학습에 미치는 영향)

  • Hyesung Park;Sungyeun Kim
    • The Mathematical Education
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    • v.63 no.3
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    • pp.437-450
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    • 2024
  • Self-directed learning in mathematics education is crucial because it enables students to think creatively and critically while continuously improving. The purpose of this study was to examine the mediating effects of class attitude and class satisfaction in mathematics on the relationship between mathematics teacher characteristics and self-directed learning. Furthermore, the study aimed to determine whether these structural relationships differ between male and female student groups. To achieve this, the theoretical model was tested using the 9th-year data (high school 3rd grade) of the Seoul Education Longitudinal Study (SELS) 2010, comprising 2,325 students (1,187 males and 1,138 females). The results revealed that the mediating effects of mathematics class attitude and class satisfaction on the relationship between teacher characteristics in mathematics and high school students' self-directed learning were significant. At this time, the direct effect of mathematics teacher characteristics on selfdirected learning was not significant, indicating that mathematics class attitude and class satisfaction had full mediating effects. Multi-group analysis results showed no significant differences in path coefficients between male and female student groups. Based on the research findings, implications for teacher education were presented to improve high school students' self-directed learning abilities in mathematics education, focusing on the mediating effects of affective factors in the classroom.

Discussion on Detection of Sediment Moisture Content at Different Altitudes Employing UAV Hyperspectral Images (무인항공 초분광 영상을 기반으로 한 고도에 따른 퇴적물 함수율 탐지 고찰)

  • Kyoungeun Lee;Jaehyung Yu;Chanhyeok Park;Trung Hieu Pham
    • Economic and Environmental Geology
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    • v.57 no.4
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    • pp.353-362
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    • 2024
  • This study examined the spectral characteristics of sediments according to moisture content using an unmanned aerial vehicle (UAV)-based hyperspectral sensor and evaluated the efficiency of moisture content detection at different flight altitudes. For this purpose, hyperspectral images in the 400-1000nm wavelength range were acquired and analyzed at altitudes of 40m and 80m for sediment samples with various moisture contents. The reflectance of the sediments generally showed a decreasing trend as the moisture content increased. Correlation analysis between moisture content and reflectance showed a strong negative correlation (r < -0.8) across the entire 400-900nm range. The moisture content detection model constructed using the Random Forest technique showed detection accuracies of RMSE 2.6%, R2 0.92 at 40m altitude and RMSE 2.2%, R2 0.95 at 80m altitude, confirming that the difference in accuracy between altitudes was minimal. Variable importance analysis revealed that the 600-700nm band played a crucial role in moisture content detection. This study is expected to be utilized in efficient sediment moisture management and natural disaster prediction in the field of environmental monitoring in the future.

Effect of Expanded Polystyreneon Growth and Development Time of Tenebrio molitor (발포폴리스티렌이 Tenebrio molitor의 성장 및 발달 기간에 미치는 영향)

  • Ji Yun Yun;Se Min Lee;Soo Jin Jeong;Ava Johnston;Emelyn Anderson;Steven Kim;Dong Sub Kim
    • Journal of Bio-Environment Control
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    • v.33 no.3
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    • pp.172-177
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    • 2024
  • Many studies have reported that mealworms can ingest plastic during their larval stage. The purpose of this study was to investigate the effects of expanded polystyrene consumption on the growth and development of mealworms during their larval stage. We found that the growth rate is significantly different between mealworms consumed wheat bran and mealworms consumed expanded polystyrene (p < 0.001). The transformation into pupa occurred faster among the mealworms consumed expanded polystyrene than those consumed wheat bran (p < 0.001). However, the survival rate was not significantly different between the two groups of mealworms (p = 0.786). Based on the data, we conclude that mealworms consuming expanded polystyrene have a slower weight gain and a shorter development period than mealworms consuming wheat bran, but the expanded polystyrene does not affect the survival rate before the transformation into pupa. Practically, we anticipate that mealworms can be a resource for the sustainable and eco-friendly removal of expanded polystyrene waste.

Study on the shielding performance of bismuth oxide as a spent fuel dry storage container based on Monte Carlo simulation

  • Guo-Qiang Zeng;Shuang Qi;Peng Cheng;Sheng Lv;Fei Li;Xiao-Bo Wang;Bing-Hai Li;Qing-Ao Qin
    • Nuclear Engineering and Technology
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    • v.56 no.8
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    • pp.3307-3314
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    • 2024
  • For traditional spent fuel shielding materials, due to physical and chemical defects and cost constraints, they have been unable to meet the needs. Therefore, this paper carries out the first discussion on the application and performance of bismuth in neutron shielding by establishing Monte Carlo simulation on the neutron flux model of shielded spent fuel. Firstly, functional fillers such as bismuth oxide, lead oxide, boron oxide, gadolinium oxide and tungsten oxide are added to the matrices to compare the shielding rates of aluminum alloy matrix and silicone rubber matrix. The shielding rate of silicone rubber mixture is higher than aluminum alloy mixture, reaching more than 56%. The optimal addition proportion of bismuth oxide and lead oxide is 30%, and the neutron radiation protection efficiency reaches 60%. Then, the mass attenuation coefficients of bismuth oxide, lead oxide, boron oxide, gadolinium oxide and tungsten oxide in silicone rubber matrix are simulated with the change of functional fillers proportion and neutron energy. This simulation result shows that the mixture with functional fillers has good shielding performance for low energy neutrons, but poor shielding effect for high energy neutrons. Finally, in order to further evaluate the possibility of replacing lead oxide with bismuth oxide as shielding material, the half-value layers and various properties of bismuth oxide and lead oxide are compared. The results show that the shielding properties of bismuth oxide and lead oxide are basically the same, and the mechanical properties, heat resistance, radiation resistance and environmental protection of bismuth oxide are better than that of lead oxide. Therefore, in the case of neutron source strengths in the range of 0.01-6 MeV and secondary gamma rays produced below 2.5 MeV, bismuth can replace lead in neutron shielding applications.