• Journal of the Korea Society for Simulation
• /
• v.32 no.4
• /
• pp.77-84
• /
• 2023

In the agricultural sector, power sources are being developed that use alternative energy sources such as electric tractors and hydrogen tractors, away from internal combustion engine tractors. As parts such as engines and transmissions used in conventional internal combustion engine tractors are replaced with motors and batteries, the center of gravity changes, and thus the risk of rollover should be considered. The purpose of this study is to analyze the overturn angle of the main parts of the electric tractor through dynamic simulation to minimize the overturn accident and to derive the optimal arrangement of parts to improve stability. A total of nine dynamics simulations were conducted by designing three components of the PTO motor, drive motor and the battery pack, and three factors of the arrangement method. As a result of the experiment, it was confirmed that Type3 Level3, in which the drive motor and the PTO motor are located at the front and rear of the tractor, and two battery packs are located in the middle of the tractor, has a high rollover angle. As a result of this study, the stability increased as the center of gravity was placed backward and located below. Future research needs to be done to find the optimal location of parts considering their performance and placement efficiency.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.18 no.4
• /
• pp.51-63
• /
• 2023

The purpose of this study is to develop and implement a secondary teacher training program based on the TPACK model to strengthen the capacity of teachers of youth entrepreneurship education in the context of the increasing importance of entrepreneurship as a future competency, and to provide theoretical and practical implications based on it. To this end, a teacher training program was developed through the process of analysis, design, development, implementation, and evaluation based on the ADDIE model, and 22 secondary school teachers in Gangwon Province were trained and the effectiveness and validity were analyzed. First, the results of the paired sample t-test of TPACK in entrepreneurship education conducted before and after the program showed statistically significant improvements in all sub-competencies. Second, the satisfaction survey of the training program showed that the overall satisfaction was high with M=4.83. Third, the validity of the program was reviewed by three experts, and it was found to be highly valid with a validity of M=5.0, usefulness of M=4.7, and universality of M=5.0. Based on the results, it is suggested that in order to expand entrepreneurship education, opportunities for teachers' holistic capacity building such as TPACK should be expanded, teachers' understanding and practice of backward design should be promoted, and access to various resources that can be utilized in entrepreneurship education should be improved.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.39 no.4
• /
• pp.214-221
• /
• 2023

In order to fabricate stable dentures in patients with severe resorption of residual ridges, various factors must be considered. One of them is the neutral zone, which is defined as the potential region in which the pressure of the tongue outward in the oral cavity and the pressure of the cheeks and lips directed inward from the outside of the oral cavity equalize during functioning. In patients with severe ridge resorption, if the teeth are usually arranged above the residual ridge, the teeth are located on the lingual side rather than the original position. Therefore, the functional space of the tongue is invaded, the tongue is positioned backward, and the sealing of the lingual border is broken, which acts as a factor reducing the maintenance of denture. In addition, it is also important for the stability of dentures to assume an interalveolar crest line connecting the maxillary and mandibular ridge crests, and to arrange the maxillary and mandibular artificial teeth to match the masticatory force to the interalveolar crest line. Therefore, good clinical results were obtained by fabricating dentures for the patient with poor alveolar residual ridge using neutral zone impression and ridge relationship analysis.

• The korean journal of orthodontics
• /
• v.34 no.1 s.102
• /
• pp.93-107
• /
• 2004

Enlow's counterpart analysis explains the complex with anatomic and developmental characteristics where craniofacial aspect of Individuals has been developed. Counterpart analysis does not compare individual measurement with the normal value from the average of majority but analyzes by comparison of values that each individual has. In this study we examined surgical changes in skeletal Class III malocclusion patients(male 40, female 40) and compared them with normal occlusion patients using counterpart analysis. The results indicated that : 1. Skeletal anterior-posterior discrepancy was relieved by shortening of the ramus width(B3). 2. The ramus alignment(R3, R4) was displaced posteriorly and the occlusal plane angle(R5) was rotated clockwise. 3. Skeletal Class III pattern was relieved in the post-operative group, but differences in the level of the cranium(R1, R2) was remaining compared to the normal occlusion patients. 4. In the comparison of surgery methods, the two-jaw surgery group presented changes In the maxillary length(A4), ramus alignment(R3, R4) and occlusal plane angle(R5) compared to the one-jaw surgery group, but the differences were not significant. In the past study about Korean skeletal Class m patients, the skeletal characteristics are upward backward rotation of the cranial base, posterior displacement of the maxilla, forward inclination of the ramus and lengthening of the mandibular body, but in this study, skeletal Class m pattern was relieved by shortening of the ramus width and maxillary advancement by orthognathic surgery, because orthognathic surgery is usually performed on limited areas in the maxilla and the mandible.

• The korean journal of orthodontics
• /
• v.32 no.3 s.92
• /
• pp.209-225
• /
• 2002

Enlow's counterpart analysis reflects the characteristics of each individual sample to find out the cause of the malocclusion and further applying them to the clinic. Enlow's counterpart analysis was performed on 100 Korean samples (50 male, 50 female) with normal occlusion and 100 skeletal class III patients (50 male, 50 female) scheduled for orthognathic surgery. The following conclusions were obtained. 1. The cause of malocclusion in skeletal class III patients were complex and interrelated : backward upward rotation of the cranial base, forward inclination of the ramus, increase in the mandibular body length, and posteriorly located maxilla. 2. Seen on R2 (male-1.68mm, female-2.33mm), in skeletal class III, the maxilla Is mote posteriorly located than the normal group. 3. The cause of malocclusion In skeletal class III patients, consists of retrognathic maxilla(A1) male $22\%$, female $26\%$, prognathic mandible(B1) male $44\%$, female $34\%$, and combination of an retrognathic maxilla and prognathic mandible were male $28\%$, female $38\%$. 4. There was no significant difference in the anterior-posterior length of the maxilla(A4) between skeletal class III males with the normal group, while in the female subjects, the skeletal class m group showed a smaller maxilla(A4) compared to the normal group. 5. In skeletal class III patients the proganthic mandible was primarily caused by the Inclination of the ramus(R3, R4) and mandibular body length(B4, B6) rather than ramus width(B3).

• Journal of Intelligence and Information Systems
• /
• v.22 no.1
• /
• pp.139-157
• /
• 2016

Bankruptcy involves considerable costs, so it can have significant effects on a country's economy. Thus, bankruptcy prediction is an important issue. Over the past several decades, many researchers have addressed topics associated with bankruptcy prediction. Early research on bankruptcy prediction employed conventional statistical methods such as univariate analysis, discriminant analysis, multiple regression, and logistic regression. Later on, many studies began utilizing artificial intelligence techniques such as inductive learning, neural networks, and case-based reasoning. Currently, ensemble models are being utilized to enhance the accuracy of bankruptcy prediction. Ensemble classification involves combining multiple classifiers to obtain more accurate predictions than those obtained using individual models. Ensemble learning techniques are known to be very useful for improving the generalization ability of the classifier. Base classifiers in the ensemble must be as accurate and diverse as possible in order to enhance the generalization ability of an ensemble model. Commonly used methods for constructing ensemble classifiers include bagging, boosting, and random subspace. The random subspace method selects a random feature subset for each classifier from the original feature space to diversify the base classifiers of an ensemble. Each ensemble member is trained by a randomly chosen feature subspace from the original feature set, and predictions from each ensemble member are combined by an aggregation method. The k-nearest neighbors (KNN) classifier is robust with respect to variations in the dataset but is very sensitive to changes in the feature space. For this reason, KNN is a good classifier for the random subspace method. The KNN random subspace ensemble model has been shown to be very effective for improving an individual KNN model. The k parameter of KNN base classifiers and selected feature subsets for base classifiers play an important role in determining the performance of the KNN ensemble model. However, few studies have focused on optimizing the k parameter and feature subsets of base classifiers in the ensemble. This study proposed a new ensemble method that improves upon the performance KNN ensemble model by optimizing both k parameters and feature subsets of base classifiers. A genetic algorithm was used to optimize the KNN ensemble model and improve the prediction accuracy of the ensemble model. The proposed model was applied to a bankruptcy prediction problem by using a real dataset from Korean companies. The research data included 1800 externally non-audited firms that filed for bankruptcy (900 cases) or non-bankruptcy (900 cases). Initially, the dataset consisted of 134 financial ratios. Prior to the experiments, 75 financial ratios were selected based on an independent sample t-test of each financial ratio as an input variable and bankruptcy or non-bankruptcy as an output variable. Of these, 24 financial ratios were selected by using a logistic regression backward feature selection method. The complete dataset was separated into two parts: training and validation. The training dataset was further divided into two portions: one for the training model and the other to avoid overfitting. The prediction accuracy against this dataset was used to determine the fitness value in order to avoid overfitting. The validation dataset was used to evaluate the effectiveness of the final model. A 10-fold cross-validation was implemented to compare the performances of the proposed model and other models. To evaluate the effectiveness of the proposed model, the classification accuracy of the proposed model was compared with that of other models. The Q-statistic values and average classification accuracies of base classifiers were investigated. The experimental results showed that the proposed model outperformed other models, such as the single model and random subspace ensemble model.

• Korean Journal of Applied Biomechanics
• /
• v.12 no.2
• /
• pp.51-63
• /
• 2002

This study sought to identify the kinematic characteristics at entrance to the straight course from the curvilinear course in the 200m-track game. For this purpose, this study was conducted for 4 sprinters by setting the 10m-section combined from the curvilenear track to the straight course and shooting them with the camcorder. It was set up to include all the sections of analysis by using the framework of the control point knowing the coordinate of the space and actual analysis was conducted on the motion showing the best records by conducting it for each subject five times. As a result, the following conclusion was drawn: It was found that the subjects showed the average stride of 4.5${\pm}$0.41 times at the 10-meter section and the required time of 1.42${\pm}$0.04sec. They showed the ratio average stride to height of 1.25${\pm}$0.20% and the average speed of 7.06${\pm}$0.19m/s. The displacement in the center of gravity of the human body at the section combined from the curvilinear course to the straight course was moving along the inward course of the curvilinear course, and the displacement of the leg located at the outward direction(right) was found to be larger than that of the leg located at the inward direction(left). In the speed of the left and right hand segments, it was found that the speed of the right hand located in the outward direction was faster than that of the left hand located at the inward, and it was found that the subjects progressed in the curvilinear course. The subjects showed the larger angle of the shoulder joint when the upper arm was located in the forward direction than when the it was located in the backward direction. In the curvilinear course, they showed the lower value of the lateral angle of the trunk when the right foot located at the outward direction left the ground than when the left foot located at the inward direction left the ground. And it was found that the lateral angle of the trunk became lower with approaching the straight course.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.44 no.3
• /
• pp.1-12
• /
• 2016

This study aimed to interpret the fundamental cause of road-kill occurrences and analyzed spatial characteristics of the road-kill locations from Route 44 in Seorak National Park, Korea. Logistic regression analysis was utilized for backward elimination on variables. Seorak National Park Service has constructed GIS-data of 81 road-kill occurrences from 2008 to 2013 and these data were assigned as dependent variables in this study. Considered as independent variables from previous studies and field surveys, vegetation age-class, distance to streams, coverage of fences and retaining walls, and distance to building sites were assigned as road-kill impact factors. The coverage of fences and retaining walls(-1.0135) was shown as the most influential factor whereas vegetation age-class(0.0001) was the least influential among all of the significant factor estimates. Accordingly, the rate of road-kill occurrence can increase as the distance to building sites and stream becomes closer and vegetation age-class becomes higher. The predictive accuracy of road-kill occurrence was shown to be 72.2% as a result of analysis, assuming as partial causes of road-kill occurrences reflecting spatial characteristics. This study can be regarded as beneficial to provide objective basis for spatial decision making including road-kill occurrence mitigation policies and plans in the future.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.2
• /
• pp.97-109
• /
• 2022

Purpose: This study aims to investigate the risk indicators contributing to implant failure, and analyze the relationship between risk indicators and marginal bone loss (MBL) through long-term follow-up over 3 years. Materials and Methods: From 2003 to 2017, patients' medical charts with a history of dental implant surgery at Chonnam National University Dental Hospital were reviewed retrospectively. The patient's demographic variables, and clinical variables were recorded. Periapical radiographs were used to evaluated the changes in MBL around implants. And we analyzed implant survival rates. Multiple regression analysis with backward elimination was conducted to correlate the patient's clinical variables and implant failure and Pearson correlation analysis was performed to the correlated between implant long-term survival rates and MBL and initial stability. Results: In multiple regression analysis, there was a statistically significant negative correlation between abutment connection type (β = -.189, P < .05), with or without SPT (β = -.163, P < .05), diabetes (β = -.164, P < .05), osteoporosis (β = -.211, P < .05) and MBL. Anticoagulant medication influenced the long-term success rate of implants. PTV values at the second implant surgery showed a statistically significant negative correlation with long-term implant survival (P < .05). Conclusion: For the long-term success of the implant, the appropriate abutment connection type must be selected and the periodic SPT is recommended. Systemic diseases such as diabetes and osteoporosis and anticoagulant medication should be considered. Furthermore, since high PTV at the second implant surgery correlated with the long-term survival rates of the implant, initial stability should be carefully considered before undergoing the prosthetic procedure.

• Journal of agricultural medicine and community health
• /
• v.39 no.3
• /
• pp.176-186
• /
• 2014

Objectives: As a sequel to the former analysis of the quality of life (QoL) among young-old and old-old in Korea, this research was aimed to identify factors related to the quality of life and the gender difference after controlling for the related factors among Korean elderly. Methods: Selected elderly data of 1,339 subjects from the 5th Korea National Health and Nutrition Examination Survey conducted in 2010 was analyzed. In this survey, QoL was measured using Euro Quality of Life (EQ-5D) instrument. Data were analyzed using complex survey data analysis on IBM-SPSS 20.0. The related factors were identified using general linear models with backward elimination. The gender difference was tested also using general linear models. Results: The distributions of educational level, family income level, and presence of cohabitant were different between male and female elderly in both young-old and old-old age group. So were the health behaviors and perceived health, and experience of stress, depression, and suicidal thoughts. QoL and its subscales- mobility, self care, daily living, pain and discomfort, and anxiety and depression- were consistently better among male elderly regardless of age group. Among the variables considered, education, family income level, presence of cohabitant, perceived health, age group and BMI were found to be related to the QoL at p=.05, and presence of chronic diseases at p=.10. The difference in QoL between male and female elderly after controlling for the variables was statistically significant. Conclusion: Improving QoL is particularly important for the elderly. In order to improve QoL of the elderly, age- and gender- differences need to be considered when developing services and programs for the elderly.