• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.205-215
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• 2006

In this study 3-D shell FEM model was applied to analyze the behavior of curved steel box girders stiffened by diaphragms. The reliability of the analytical method has been proved by comparing with the existing results. It was also found from this analysis that main factors affecting a distortional stress are length of a girder, curvature of the girder, and spacing of diaphragms. A modelled bridge with 30m of span length and 40m of radius was analyzed to find an optimum spacing of diaphragm, and as a result of applying different spacings, 5m was found to be most appropriate to control the stress ratio regulated by specifications. In the effect of diaphragm shape, the rhamen-typed diaphragm is found to be more effective than the fully filled-up one in the range of opening ratio of 0.4 to 0.6. But, the fully filled-up diaphragm had more efficiency in terms of reducing the distortional stress than X-truss typed diaphragm.

• Journal of Venture Innovation
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• v.7 no.2
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• pp.57-76
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• 2024

A virtual influencer is a digital artifact that primarily operates on social media and acts like the human influencer. This study investigate how the attractiveness and reputation of virtual influencers affect consumers' purchase intentions. Based on previous studies, we developed a research model and questionnaire, and analyzed a total of 371 survey questionnaires using a structural equation model. The study results show that reputation positively affect attachment, imitation desire, and interaction, while attractiveness positively influence attachment and imitation desire but not interaction. Lastly, purchase intention was positively influenced by imitation desire, attachment, and interaction; which indicates that attractiveness, reputation, and interactivity are crucial factors in virtual influencer implementation strategies. The quality and reliability of contents provided by virtual influencers are essential not only for gaining popularity but also for maintaining a good reputation. Additionally, continuous interaction is necessary in order to foster close relationships with consumers. A few practical insights are presented for firms considering to implement a virtual influencer.

• Tunnel and Underground Space
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• v.34 no.4
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• pp.301-311
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• 2024

In South Korea, following the 2016 Gyeongju and 2017 Pohang earthquakes, the need for earthquake disaster prevention has been increasing. Reliable techniques for probabilistic seismic hazard analysis and ground motion models are required for quantifying earthquake damage. Recently, there has been growing demand for deep underground facilities, necessitating accurate quantification techniques for earthquake damage in deep underground. In this study, ground motion models within rock were proposed using ground motion data measured at borehole seismic stations. A regression analysis, a type of empirical technique, was applied to 17 periods selected in a range from 0.01 to 10 s of spectral accelerations to develop the ground motion models. Residual analysis was performed to evaluate and improve the prediction performance of the ground motion model, with correction factors added to the model equation. When applying the proposed model, the group means of residuals approached zero, and the standard deviation of total residuals, similar to existing models proposed in other countries, confirmed the reliability of the proposed model.

• Smart Structures and Systems
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• v.33 no.5
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• pp.365-374
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• 2024

This paper adopts a new approach in which nonlinear vibrations can be controlled using fuzzy controllers by optimal grey evolutionary algorithm. If the fuzzy controller cannot stabilize the systems, then the high frequency is injected into the system to assist the controller, and the system is asymptotically stabilized by adjusting the parameters. This paper uses the GM (grey model) and the neural network prediction model. The structure of the neural network is improved from a single factor, and multiple data inputs are extended to various factors and numerous data inputs. The improved model expands the applicable range of uncontrolled elements and improves the accuracy of controlled prediction, using the model that has been trained and stabilized by multiple learning. The simulation results show that the improved gray neural network model has higher prediction accuracy and reliability than the traditional GM model, improving controlled management and pre-control ability. In the combined prediction, the time series parameters and the predicted values obtained from the GM (1,1) (Grey Model of first order and one variable) are simultaneously used as the input terms of the neural network, considering the influence of the non-equal spacing of the data, which makes the results of the combined gray neural network model more rationalized. By adjusting the model structure and system parameters to simulate and analyze the controlled elements, the corresponding risk change trend graphs and prediction numerical calculation results are obtained, which also realize the effective prediction of controlled elements. According to the controlled warning principle and objective, the fuzzy evaluation method establishes the corresponding early warning response method. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage.

• Journal of the Korea Society of Computer and Information
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• v.29 no.9
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• pp.255-268
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• 2024

The purpose of this study was to analyze the effect of service quality and privacy risk on customer satisfaction and continuous use intention for convenience store parcel delivery service, and verify the moderating effect of contactless tendency. This study employed PLS-path modeling to test the research hypotheses. The results of the study were as follows: 1) service quality factors of convenience store parcel delivery (i.e., service price, reliability, and convenience) had significant effects on customer satisfaction. However, responsiveness had no significant effect on customer satisfaction; 2) privacy risk had a significant effect on both customer satisfaction and continuous use intention; 3) customer satisfaction had a significant effect on continuous use intention; and 4) contactless tendency moderated the relationship between responsiveness and satisfaction. The findings of the study are expected to provide valuable insights for future research and the development of practical service strategies.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.271-276
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• 2024

The success of construction projects is influenced by various factors, with accurate management and prediction of the construction period playing a crucial role. The construction period is determined through contracts between the client and the contractor, and it is considered a key element in the management of construction projects, alongside cost management. To ensure the successful completion of projects, accurate prediction of the construction period is essential, as it aids in the efficient allocation of time and resources. The main objective of this study is to maximize the performance of construction period prediction models by applying and comparing various methods for handling missing data. Optimizing the model's performance requires accuracy and completeness of data, with the process of outlier removal and missing data imputation potentially having a significant impact on the model's predictive capability. During this process, the effect of changes in the dataset on model performance will be closely examined to identify the most effective method for handling missing data. Outlier removal and missing data imputation are crucial steps in the data preprocessing phase, and they can significantly improve the model's accuracy and reliability. This research aims to apply these data preprocessing methods and analyze their outcomes to find the most effective missing data imputation method for construction period prediction. After the selection process, considering the model's performance and stability, the mode imputation method was identified as the most suitable for predicting the construction period. The findings of this research are expected to contribute not only to improving the accuracy of construction period predictions but also to enhancing the overall efficiency and success rate of construction project management.

• Journal of radiological science and technology
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• v.47 no.5
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• pp.367-374
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• 2024

Education on start-ups and social support through various programs can greatly assist students who are either planning to start a business or have future entrepreneurial aspirations. This study aims to examine the impact of entrepreneurship education, social support, and awareness of the intend to start a business for students enrolled in radiological science program at local universities. The reliability of the questionnaire tool was confirmed with a Cronbach's Alpha coefficient of .06 or higher in the variable. The result of the independent sample t-test using the Boot Strap technique was classified by gender, revealed significant differences in the intention to start a business and innovation. The Bias-Corrected and Accelerated (BCa) 95% confidence interval for the intention to start a business and innovation was lower at .268 and .100, respectively, and the upper limit was .825 and .457, indicating a significant difference as the interval did not include zero. As a result of regression analysis, analysis demonstrated that among the sub-factors of entrepreneurship, innovation (p<.05) and risk sensitivity (p<.001) significantly influenced the willingness to start a business. These findings suggest that comprehensive education on start-ups, along with the provision of appropriate support mechanisms, is essential to ensure the students do not miss out on entrepreneurial opportunities due to a lack of related resources and support.

• Journal of Educational Research in Mathematics
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• v.8 no.1
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• pp.11-29
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• 1998

The purpose of this thesis was to improve the plans and methods of teaching and learning activities and contribute to developing teachers` quality and reeducating them by investigating teachers' attitudes toward teaching and learning have a significant effect on the students' attitudes toward mathematics and the students' ability development at mathematics. The inventory was composed of 56 items : three main areas and eight sub-areas. Added seven background factors were sex, by whom was established (is it a public or nongovernmental \ulcorner), teaching career, age, what kind of school (is it general or vacational high school or middle school\ulcorner), region, college. For this analysis of materials used SAS program. And analysis of variance was applied on the seven background factors. All subjects in this study were 341 secondary school mathematics teachers in pusan city and Kyungsangnam-do were surveyed by the questionnaire of Likert type to which the respondents' seven background elements were added. Main results this study were as follows : 1. The overall attitude of the measured secondary school mathematics teachers tends to be positive but a little indifferent. Also attitude toward the students was a little more positive than the other attitudes. 2. There were significant differences (1%) among the sub-level areas except three of them. (r = 0.17~0.60) 3. There were significant differences (5%) by the result of Multiple comparison test among the schools in learning and teaching. So the teachers working at middle schools and general high schools were more positive than those working at vocational high schools. 4. The result of comparison among region was that teachers working in towns and cities were more positive than those working in the country. But there was no significant difference between the teachers working in large cities and those working in other region. 5. There was no significant difference in the overall attitudes toward teaching and learnig among the sex, by whom was established(is it public or nongovernmental\ulcorner), teaching career, age, college. The study left much deficiency to be desired and has to be followed by a continuing study to make it better. For the following study, it is necessary to examine the validity and reliability of the measuring tools more thoroughly and investigate the attitudes with sufficient samples all over the country.

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.997-1006
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• 2003

This study was conducted to investigate the national methane emission from livestock enteric fermentation. For methane emission estimation, livestock were mainly categorized to cattle, swine, poultry, sheep, goats and horses, and cattle were further sub-categorized to calves, fattening cattle, breeding cows in Hanwoo and calves, fattening cattle and lactating cows in dairy cattle. Tier 2 methane emission factors were deduced based on the characteristics of animal performances, live weight, slaughter weight, daily weight gain, and feed digestibility in each category. Tier 2 emission factors of Hanwoo range from 39 to 49 kg/head/year and it is similar to that of Tier 1(47kg/head/year). Tier 2 emission factor of dairy cattle was 107 kg/head/year and it is slightly lower than that of Tier 1(118kg/head/year). Total methane emission from livestock enteric fermentation by Tier 2 method was estimated to be 126.8 tones in 2001. The methane emissions by Hanwoo, dairy cattle, swine, goats, horses and sheep were 61.70, 47.76, 13.08, 2.25, 0.17 and 0.01 tones, respectively. By the use of Tier 2 method instead of Tier 1, the accuracy and reliability of methane emission estimates from livestock enteric fermentation in Korea is considered to be improved.

• Korean Journal of Environment and Ecology
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• v.21 no.6
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• pp.554-558
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• 2007

Current biomass stock of forest has been calculated by using biomass expansion factors (BEFs) that convert timber volumes to dry weight and stem density. The objective of this study was to estimate stem density values and to develop BEFs that are dependent on tree age classes for Quercus acuta stands in Jeonnam Wando-gun. Sample trees on the three different age classes were harvested to obtain each components biomass with stem analysis. Stem density values as tree age classes were ranged from 0.557 to 0.636. Aboveground BEFs were ranged from 1.168 to 1.324. BEFs were increased with increasing age classes. There was a significant difference between BEFs and stem density values with tree age classes. These results suggest that the reliability of the national carbon stock inventory could be improved by applying age classes BEFs, which are formulated on the basis of representative for Quercus acuta.