• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.150-150
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• 2022

This study investigates the roles of decomposition methods on high accuracy in daily rainfall prediction from light gradient boosting machine (LightGBM) algorithm. Here, empirical mode decomposition (EMD) and singular spectrum analysis (SSA) methods were considered to decompose and reconstruct input time series into trend terms, fluctuating terms, and noise components. The decomposed time series from EMD and SSA methods were used as input data for LightGBM algorithm in two hybrid models, including empirical mode-based light gradient boosting machine (EMDGBM) and singular spectrum analysis-based light gradient boosting machine (SSAGBM), respectively. A total of four parameters (i.e., temperature, humidity, wind speed, and rainfall) at a daily scale from 2003 to 2017 is used as input data for daily rainfall prediction. As results from statistical performance indicators, it indicates that the SSAGBM model shows a better performance than the EMDGBM model and the original LightGBM algorithm with no decomposition methods. It represents that the accuracy of LightGBM algorithm in rainfall prediction was improved with the SSA method when using multivariate dataset.

• Educational Technology International
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• v.11 no.1
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• pp.1-26
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• 2010

The purpose of this study was to identify differences in teachers perception on educational attributes and effectiveness of IPTV according to demographic factors. To investigate possibility of educational application, the participants of the study were teachers selected from IPTV initiative schools in elementary and middle levels nationwide. 55 teachers participated from 22 IPTV model schools nationwide, which were 9 elementary schools, 6 middle schools, 7 high schools. As results of research, there were some significant foundings. In terms of the perception on educational attributes of IPTV, there are explicit perceptional difference between "capital area teachers" and "the other regional teachers". However, there were no significant difference according to school level. Perception of male teachers were more positive than those of female teachers. Also, there were no significant difference according to teaching experience. On the other hand, in terms of the perception on educational effects of IPTV, we could conclude that teachers from metropolitan cities have more negative perception on IPTV than teachers from other kinds of cities have. Regardless of school levels, teachers showed merely fair perception on effectiveness of IPTV. There was significant difference between male teachers and female teachers in perception on educational effectiveness. Also, Results showed no significant differences according to teaching experiences. Future tasks for the development of IPTV strategies require specific need analysis of teachers and collaborative works of policy makers, teachers, researchers, and IPTV service providers.

• Current Optics and Photonics
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• v.7 no.5
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• pp.485-495
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• 2023

The pixel size in high-resolution complementary metal-oxide-semiconductor (CMOS) image sensors continues to shrink due to chip size limitations. However, the pixel pitch's miniaturization causes deterioration of optical performance. As one solution, a quad color filter (CF) array with pixel binning has been developed to enhance sensitivity. For high sensitivity, the microlens structure also needs to be optimized as the CF arrays change. In this paper, the covered microlens, which consist of four microlenses covered by one large microlens, are proposed for the quad CF array in the backside illumination pixel structure. To evaluate the optical performance, the suggested microlens structure was simulated from 0.5 ㎛ to 1.0 ㎛ pixels at the center and edge of the sensors. Moreover, all pixel structures were compared with and without in-pixel deep trench isolation (DTI), which works to distribute incident light uniformly into each photodiode. The suggested structure was evaluated with an optical simulation using the finite-difference time-domain method for numerical analysis of the optical characteristics. Compared to the conventional microlens, the suggested microlens show 29.1% and 33.9% maximum enhancement of sensitivity at the center and edge of the sensor, respectively. Therefore, the covered microlens demonstrated the highly sensitive image sensor with a quad CF array.

• East Asian Journal of Business Economics (EAJBE)
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• v.12 no.1
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• pp.13-22
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• 2024

Purpose: The purpose of this study is to investigate impact of smart city awareness on citizen satisfaction and to measure various factors influencing smart city competitiveness that were rarely addressed in previous studies. For the impacts on the competitiveness of smart cities, this study explored the effects of data-driven service, economic impact, social trust through sharing, environmental protection, and sustainable growth. Research design, data and methodology: To collect data, this study employed an online survey conducted by a reputable research organization. Data analysis involved the use of factor analysis, ANOVA, and regression analysis. Results: This study identified key aspects important for enhancing citizen satisfaction. Furthermore, this research unveiled the significant impacts of data-driven service, economic impact, social trust through sharing, environmental protection, and sustainable growth on the competitiveness of smart cities. Conclusions: The results yield valuable managerial and policy implications. The study suggests that enhancing citizen satisfaction through improved awareness of the smart city is crucial for effective city marketing management. Additionally, the results highlight special aspects necessary to improve smart city competitiveness, including the implementation of promotional policies supported by the government, promoting global competitiveness for domestic companies, and fostering citizen participation for effective city marketing management.

• International Journal of High-Rise Buildings
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• v.13 no.1
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• pp.97-102
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• 2024

In this paper, we would like to share our ongoing research on global population and demographic shifts and the corresponding need for diverse responses. As population growth varies worldwide, the pressing issue is the current global housing shortage. The USA alone lacks 4 million homes, underlining the urgency for new construction and renewal of existing. Our focus is primarily on new building processes, which must also incorporate elements of renewal for future sustainability. Our research addresses several key questions: How will roles for construction professionals change? What should be the primary goal of the design process? What types of technologies are currently available, and which aspects of the process can be enhanced with AI? A significant part of our study is exploring sustainable building methods that reduce embodied carbon and increase speed of construction. Our goal is to extend the transition from smart homes to cities, analyzing the evolution towards smart communities and cities. A critical aspect of our research is the 'kit of parts concept, involving prefabrication and modular construction. This approach is essential for both rebuilding and new projects, potentially lowering costs in manufacturing and design for long term. Lastly, we present a detailed comparison of the construction industry with manufacturing.

• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.1
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• pp.40-54
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• 2024

This study aims to identify the regional distribution in the prevalence of dental caries and related multidimensional factors among 12-year-old children in Korea. Data from the 2018 Child Oral Health Survey were used to calculate the average DMFT index of 12-year-old children in metropolitan cities, and a multi-level regression model was applied to explain the regional distribution of dental caries prevalence and related factors. Factors were divided into two levels by administrative structure. This study finds a significant regional difference in the prevalence of dental caries in 12-year-old Korean children across metropolitan cities. Multilevel analysis showed that district-level factors (average number of pit and fissure-sealed permanent teeth, dental treatment demand rate, preventive treatment rate, sex ratio, and number of dentists per 100,000 people) and metropolitan-level factors (intakes of cariogenic beverages and number of pediatric dental hospitals and clinics per 100,000 people) had a significant effect on dental caries prevalence (p < 0.05). Individual characteristics and local socio-environmental factors influence the prevalence of dental caries. Especially considering the strong dependence on preventive treatment and accessibility to dental care services, it is necessary to provide adequate preventive treatment and expand health care resources in high-risk areas of dental caries.

• Journal of Korean Society of Rural Planning
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• v.30 no.2
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• pp.79-96
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• 2024

The purpose of this study is to analyze the factors affecting residential mobility between urban and rural. After classifying urban and rural region based on discriminatory attributes of the regions, we applied a multinomial logistic model, using the sample data of 2020 Korea Population and Housing Census. The major findings are as follows. The young highly educated in cities avoided rural. The young less educated in rural engaged in 2, 3th industries as well as agricultural industry, but remained in low-paying and unstable jobs. In addition, various classes moved to rural and rising house prices in cities pushed people to rural. Therefore, it is necessary to develop diversified regional industry models and provide opportunities for high quality and stable jobs in rural by linking industrial demand, education and jobs. Also, preserving the rural environment, settlement conditions and residential environment are needed for satisfying various needs of urban residents who migrate to rural areas. While regional policies so far have focused on maintaining the population size and promoting a population influx, rural development and population policies should be established in a way that responds to diverse population classes in an era of population decline.

• Journal of the Korean Institute of Rural Architecture
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• v.26 no.2
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• pp.27-36
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• 2024

Many houses have been left vacant in cities worldwide due to changes in the economy, society, and urban composition. The increase in vacant houses causes social problems and decrease in the value of real estate. Considering the cost of preparing a new residence because the existing residence no longer functions, it is an important problem to solve empty houses in the existing residence. Accordingly, policy attempts and studies to reduce and utilize vacant houses are in progress in various countries. In South Korea, the ratio of vacant houses was 6.4% of all houses as of 2021, and in Jeolla-buk-do, it was 11.6%, which is higher than the national average. Jeollabuk-do conducted a fact-finding survey on countermeasures against vacant houses; 17,732 vacant houses (2.4%) were surveyed. The urbanization, population, and terrain of Jeollabuk-do, consisting of 14 cities and counties, were considered. The ratios, types, grades, and spatial autocorrelations of vacant houses were analyzed after classification into city areas (focus, small, and medium) and county areas (plains and mountains) areas to derive policies according to the distribution of vacant houses. The average difference in ratio, type, grade, and spatial autocorrelation of vacant houses was used to analyze the characteristics of the distribution of vacant houses according to these classifications. There were significant differences in the averages of the ratios, grades, and spatial autocorrelations between city and county areas. The autocorrelation of vacant house distribution exhibited differences between urban and county areas.

• Journal of the Korea Safety Management & Science
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• v.26 no.2
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• pp.55-64
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• 2024

As the distribution of vehicles and logistics increases due to the development of human civilization and the increase in population, various roads play an important role in domestic traffic and transportation. However, the recent emergence of large cities and new cities is causing traffic problems, and the increase in roads is inevitable for the smooth distribution of vehicles and logistics. In Korea, mountainous regions occupy 70% of the country, so tunnels are used to open roads. Without this, it is difficult to open the road. Currently, there are 3,720tunnels (as of December 31, 2023) installed on high-speed national highways, general national highways, and local roads nationwide, with a length of 2.499 and increasing every year. Accordingly, fire accidents in tunnels will also increase, and due to the nature of tunnel fire accidents, there is a high probability that they will escalate into large-scale disasters, resulting in casualties and property damage, as well as significant social losses due to the disruption of logistics transportation, etc. As the possibility of potential hazards is increasing, the purpose of this study is to build a safe and efficient tunnel system by optimizing maintenance and management for fire and disaster accidents in tunnels.

• International Journal of Computer Science & Network Security
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• v.23 no.12
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• pp.115-122
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• 2023

Makkah Al-Mukarramah is the capital of Islamic world. It receives special attention from the Saudi government's rulers to transform it into a smart city for the benefit of millions of pilgrims. One of the 2030 vision objectives is to transform specific cities to smart ones with advanced technological facilitation, Makkah is one of these cities. The history of Makkah is not well known for some Muslims. As a result, we built the concepts of our application "Ain Makkah" to enable visitors of Makkah to know the history of Makkah by using technology. In particular "Ain Makkah" uses Augmented Reality to view the history of Al-Kaaba. A 3D model will overlay Al-Kaaba to show it in the last years. Our project will use Augmented Reality to build a 3D model to overlay Al-Kaaba. Future work will expand the number of historical landmarks of Makkah.