• International Journal of Automotive Technology
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• 제4권2호
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• pp.101-108
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• 2003

There are a lot of factors that influence automotive fuel economy such as average trip time per kilometer, average trip speed, the number of times of vehicle stationary, and so forth. These factors depend on road conditions and traffic environment. In this study, various driving data were measured and recorded during road tests in Seoul. The accumulated road test mileage is around 1,300 kilometers. The objective of the study is to identify the driving patterns of the Seoul metropolitan area and to analyze the fuel economy based on these driving patterns. The driving data which was acquired through road tests was analysed statistically in order to obtain the driving characteristics via modal analysis, speed analysis, and speed-acceleration analysis. Moreover, the driving data was analyzed by multivariate statistical techniques including correlation analysis, principal component analysis, and multiple linear regression analysis in order to obtain the relationships between influencing factors on fuel economy. The analyzed results show that the average speed is around 29.2 km/h, and the average fuel economy is 10.23 km/L. The vehicle speed of the Seoul metropolitan area is slower, and the stop-and-go operation is more frequent than FTP-75 test mode which is used for emission and fuel economy tests. The average trip time per kilometer is one of the most important factors in fuel consumption, and the increase of the average speed is desirable for reducing emissions and fuel consumption.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.233-239
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• 2021

The objective of this study is to find out the factors affecting the employees' loyalty in private joint-stock commercial banks in Mekong Delta, Vietnam. Then, possible solutions can be proposed, which can be implemented to improve employees' engagement in private joint-stock commercial banks in Mekong Delta, Vietnam, in the future. The author conducted a survey of 300 employees at 6 private joint-stock commercial banks in 6 provinces in Mekong Delta: An Giang, Tra Vinh, Can Tho, Ben Tre, Soc Trang, and Tien Giang. The author also used the Cronbach Alpha reliability analysis method, exploratory factor analysis (EFA), and multivariate regression analysis. The results show the degree of influence of factors on employees' loyalty - according to decreasing importance: Income, Job characteristics, Working environment, Colleagues, Leadership. The authors propose some solutions based on the research findings, including focusing on assigning the right employees to the right jobs, creating a competitive and fair working environment, focusing on a reasonable income policy, and transparency in working relationships to help bank managers in the Mekong Delta, Vietnam improve human resource management to improve employee loyalty to private joint-stock commercial banks in Vietnam.

• Journal of Korean society of Dental Hygiene
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• 제19권3호
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• pp.409-419
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• 2019

Objectives: The purpose of this study was to analyze the factors affecting antibiotic prescription in dental outpatients. Methods: The present study was conducted using data from the National Health Insurance Service - National Sample Cohort. We analyzed prescriptions issued in the dental outpatient department in 2015, for adults over 19 years of age. Antibiotic prescription rates and mean prescription days were analyzed by sex, age, insurance type, presence of diabetes mellitus and hypertension, season in treatment, type of dental institution, and location of dental institution. Multivariate logistic regression was also performed to analyze the factors affecting antibiotic prescription in dental outpatients. Results: A total of 257,038 prescriptions were analyzed. The mean prescription days of antibiotics in dental outpatients were $3.04{\pm}1.08days$, and the prescription rate was 93.0%. Two variables (presence of diabetes mellitus and insurance type) were excluded from the multivariate logistic regression analysis model because they did not significantly affect antibiotic prescription. The possibility of antibiotic prescription was higher in men ${\geq}61years$ of age and those with hypertension. Furthermore, antibiotics were most frequently prescribed in dental clinics rather than dental hospitals, and more frequently in Busan compared to other areas (p<0.001). Conclusions: Several factors were determined to affect antibiotic prescription, and detailed guidelines for consistent antibiotic prescription are needed.

• Annals of Surgical Treatment and Research
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• 제95권5호
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• pp.258-266
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• 2018

Purpose: This study analyzes the impact of laparoscopic liver resection on intra-abdominal adhesion. Methods: Patients who underwent salvage liver transplantation after liver resection for hepatocellular carcinoma from January 2012 to October 2017 at our institution were included. Information about the severity of intra-abdominal adhesions was collected from a prospectively maintained database. Intra-abdominal adhesions were graded after the agreement of 2 surgeons who participated in the salvage liver transplantation based on predetermined criteria. Adhesion severity and demographic, operative, and postoperative data were compared between the laparoscopic group and the open group. Multivariate logistic regression was performed to consider potential factors related to severe adhesion during salvage transplantation. Results: Sixty-two patients who underwent salvage liver transplantation after liver resection were included in this study. Among them, 52 patients underwent open surgery, and 10 patients underwent laparoscopy. Adhesion was significantly more severe in the open group than in the laparoscopy group (P = 0.029). A multivariate logistic regression model including potential factors related to severe adhesion showed that laparoscopy (odds ratio, 0.168; 95% confidence interval, 0.029-0.970; P = 0.048) was the only significant factor. Conclusion: Laparoscopic liver resection for hepatocellular carcinoma can minimize intra-abdominal adhesion during salvage liver transplantation.

• Geomechanics and Engineering
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• 제16권6호
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• pp.655-667
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• 2018

To evaluate the stability of a rock slope with one pre-exiting vertical crack, this paper performs corresponding probabilistic stability analysis. The existence of cracks is generally ignored in traditional deterministic stability analysis. However, they are widely found in either cohesive soil or rock slopes. The influence of one pre-exiting vertical crack on a rock slope is considered in this study. The safety factor, which is usually adopted to quantity the stability of slopes, is derived through the deterministic computation based on the strength reduction technique. The generalized Hoek-Brown (HB) failure criterion is adopted to characterize the failure of rock masses. Considering high nonlinearity of the limit state function as using nonlinear HB criterion, the multivariate adaptive regression splines (MARS) is used to accurately approximate the implicit limit state function of a rock slope. Then the MARS is integrated with Monte Carlo simulation to implement reliability analysis, and the influences of distribution types, level of uncertainty, and constants on the probability density functions and failure probability are discussed. It is found that distribution types of random variables have little influence on reliability results. The reliability results are affected by a combination of the uncertainty level and the constants. Finally, a reliability-based design figure is provided to evaluate the safety factor of a slope required for a target failure probability.

• Geomechanics and Engineering
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• 제16권6호
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• pp.577-588
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• 2018

A major concern in deep excavation project in soft clay deposits is the potential for adjacent buildings to be damaged as a result of the associated excessive ground movements. In order to accurately determine the wall deflections using a numerical procedure such as the finite element method, it is critical to use the correct soil parameters such as the stiffness/strength properties. This can be carried out by performing an inverse analysis using the measured wall deflections. This paper firstly presents the results of extensive plane strain finite element analyses of braced diaphragm walls to examine the influence of various parameters such as the excavation geometry, soil properties and wall stiffness on the wall deflections. Based on these results, a multivariate adaptive regression splines (MARS) model was developed for inverse parameter identification of the soil relative stiffness ratio. A second MARS model was also developed for inverse parameter estimation of the wall system stiffness, to enable designers to determine the appropriate wall size during the preliminary design phase. Soil relative stiffness ratios and system stiffness values derived via these two different MARS models were found to compare favourably with a number of field and published records.

• Computers and Concrete
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• 제24권2호
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• pp.137-150
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• 2019

In this paper, surrogate models such as multivariate adaptive regression splines (MARS) and M5P model tree (M5P MT) methods have been investigated in order to propose a new formulation for the 28-days compressive strength of self-compacting concrete (SCC) incorporating metakaolin as a supplementary cementitious materials. A database comprising experimental data has been assembled from several published papers in the literature and the data have been used for training and testing. In particular, the data are arranged in a format of seven input parameters covering contents of cement, coarse aggregate to fine aggregate ratio, water, metakaolin, super plasticizer, largest maximum size and binder as well as one output parameter, which is the 28-days compressive strength. The efficiency of the proposed techniques has been demonstrated by means of certain statistical criteria. The findings have been compared to experimental results and their comparisons shows that the MARS and M5P MT approaches predict the compressive strength of SCC incorporating metakaolin with great precision. The performed sensitivity analysis to assign effective parameters on 28-days compressive strength indicates that cementitious binder content is the most effective variable in the mixture.

• Clinical and Experimental Pediatrics
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• 제64권8호
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• pp.408-414
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• 2021

Background: Complementary food in infancy is necessary for human growth, neurodevelopment, and health. However, the role of allergen consumption in early infancy and its effects on the development of food allergy or tolerance remain unclear. Purpose: To investigate the influence of age at the time of complementary food introduction on the development of asthma and atopic dermatitis in Korean children aged 1-3 years. Methods: We combined data from the Korea National Health and Nutrition Examination Survey collected from 2010 to 2014 and analyzed 1619 children aged 1-3 years who were included in the survey. Multivariate regression analysis was used to identify associations among type of feeding, age at the time of complementary food introduction, and doctor-diagnosed atopic dermatitis and asthma. Results: Age at the time of complementary food introduction was not significantly associated with doctor-diagnosed atopic dermatitis and asthma in children aged 1-3 years. In the univariate analysis, children with asthma showed higher water and sodium intake levels than nonasthmatic children. However, this relationship was not significant in the multivariate regression analysis. Conclusion: The present study revealed no statistically significant relationship between age at the time of complementary food introduction and the risk of atopic dermatitis and asthma in young Korean children. A national prospective study is needed to clarify the influence of age at the time of complementary food introduction on the development of allergic diseases.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.135-142
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• 2021

This study aims to examine the impact of audit committee characteristics on income management of companies listed on the Stock Exchange of Vietnam. Research data was collected from all 745 listed companies on Vietnam's stock market over four years, from 2015 to 2018. After excluding companies that did not qualify, there were 216 companies with 864 observations. With the help of dedicated software Stata 15, the impact of audit committee characteristics (through independent variables and control variables such as Audit Committee Independence, Auditing Committee size, Auditing Committee Expertise, Auditing Committee Meeting Frequency, Company Size, Financial Leverage, and Operating Cash Flow) to earning management through a multivariate regression model was determined. Research results from Vietnamese listed companies during this period show that the size and expertise of the audit committee are inversely related to the discretionary accruals representing earning management. At the same time, the research results also identify a positive relationship between firm size and earning management, and the inverse relationship between financial leverage, net cash flow from operating operations and earning management. However, the multivariate regression results do not find clear evidence of a relationship between audit committee independence and the audit committee meeting frequency to earning management.

• Geomechanics and Engineering
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• 제37권3호
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• pp.197-211
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• 2024

This research studies the effect of geotechnical factors on EPB-TBM performance parameters. The modeling was performed using simple and multivariate linear regression methods, artificial neural networks (ANNs), and Sugeno fuzzy logic (SFL) algorithm. In ANN, 80% of the data were randomly allocated to training and 20% to network testing. Meanwhile, in the SFL algorithm, 75% of the data were used for training and 25% for testing. The coefficient of determination (R²) obtained between the observed and estimated values in this model for the thrust force and cutterhead torque was 0.19 and 0.52, respectively. The results showed that the SFL outperformed the other models in predicting the target parameters. In this method, the R² obtained between observed and predicted values for thrust force and cutterhead torque is 0.73 and 0.63, respectively. The sensitivity analysis results show that the internal friction angle (φ) and standard penetration number (SPT) have the greatest impact on thrust force. Also, earth pressure and overburden thickness have the highest effect on cutterhead torque.