• Wind and Structures
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• v.27 no.6
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• pp.399-416
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• 2018

In order to reveal the independent relationship between track irregularity and wind loads, the stochastic characteristics of train-bridge coupling systems subjected to wind loads were investigated by the multi-sample calculation. The vehicle was selected as 23 degrees of freedom dynamical model, and the bridge was described by three-dimensional finite element model. It was assumed that the wind loads were random processes with strong spatial correlation, while the track irregularities were stationary random ones. As a case study, a high-speed train running on a cable-stayed bridge subjected to wind loads was studied. The effect of rail irregularities was deemed to be independent of the effect of wind excitations on the coupling system in the same wind circumstance for the same project, leading to the conclusion that the effect of wind loads and moving vehicle could be calculated separately. The variance results of the stochastic responses of vehicle-bridge coupling system under the action of wind loads and rail irregularities together were equivalent to the sum of the variance of the responses induced by each excitation. Therefore, when one of the input excitations is different, only the effect of changed loads needs to be assessed. Moreover, the new calculated results were combined with the effect of unchanged loads to present the stochastic response of coupling system subjected to the different excitations, reducing the cost of computations. The stochastic characteristics, the CFD (cumulative distribution function) of the coupling system with different wind velocities, vehicle speed, and vehicle marshalling were studied likewise.

• Journal of Korean Library and Information Science Society
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• v.50 no.2
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• pp.25-42
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• 2019

This study identified the experiences that the disabled actually feel in the library space in the face of growing social demands for spatial functions in public libraries. This study also tried to determine the requirements for the space that disabled wanted. For the research, 15 subjects were selected for each of the five people who were blind, deaf, and handicapped with experience using the library and individual in-depth interviews were conducted for the research. The study found that the experience of the disabled in the library space differed by type of disability and generally more negative experiences were found than positive ones. Misperception about the disabled of library staff and the non-disabled were having a significant impact on the disabled's negative experience for library space. There were a wide variety of opinions on the requirements for library space and there were generally negative perceptions about the current level of library space for the Integrated library service space.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.211-216
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• 2022

Steganography technology protects the existence of hidden information by embedding a secret message in a specific location on the cover medium. Security and resistance are strengthened by applying various hybrid methods based on encryption and steganography. In particular, techniques to increase chaos and randomness are needed to improve security. In fact, the case where the shuffling method is applied based on the discrete cosine transform(DCT) and the least significant bit(LSB) is an area that needs to be studied. I propose a new approach to hide the bit information of Hangul messages by integrating the selective shuffling method that can add the complexity of message hiding and applying the spatial domain technique to steganography. Inverse shuffling is applied when extracting messages. In this paper, the Hangul message to be inserted is decomposed into the choseong, jungseong and jongseong. It improves security and chaos by applying a selective shuffling process based on the corresponding information. The correlation coefficient and PSNR were used to confirm the performance of the proposed method. It was confirmed that the PSNR value of the proposed method was appropriate when compared with the reference value.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.291-297
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• 2021

The current formal and memorized design repetition training and practice is wandering in the uniform flat design thinking expression. To change these two-dimensional current issues into a three-dimensional design method, set the direction for each grade level under the integrated convergence educational goal and carry out projects step by step to understand design, the principle of spatial composition, the introduction of traditional design history, and the overall design of craft design. Creative and practical skills such as approach should be cultivated. Designers can only be produced through systematic education and training. In order to lead society and succeed, a designer who has experienced solutions and countermeasures on how to adapt themselves to the demands of various changes in the times must come to the field. Education experts insisted on innovation of the organizational structure and subject of the education system, and emphasized the importance of education in response to the rapid pace of change in the 21st century. This study aims to propose an educational system that combines academic research with a structural approach to tasks by setting a project that reflects the needs of society for convergence practice in which design and adjacent disciplines are linked through understanding and analysis of these issues.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.161-161
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• 2023

Bias correction of values is a necessary step in downscaling coarse and systematically biased global climate models for use in local climate change impact studies. In addition to univariate bias correction methods, many multivariate methods which correct multiple variables jointly - each with their own mathematical designs - have been developed recently. While some literature have focused on the inter-comparison of these multivariate bias correction methods, none have focused extensively on the effect of diverse configurations (i.e., different combinations of input variables to be corrected) of climate variables, particularly high-dimensional ones, on the ability of the different methods to remove biases in uni- and multivariate statistics. This study evaluates the impact of three configurations (inter-variable, inter-spatial, and full dimensional dependence configurations) on four state-of-the-art multivariate bias correction methods in a national-scale domain over South Korea using a gridded approach. An inter-comparison framework evaluating the performance of the different combinations of configurations and bias correction methods in adjusting various climate variable statistics was created. Precipitation, maximum, and minimum temperatures were corrected across 306 high-resolution (0.2°) grid cells and were evaluated. Results show improvements in most methods in correcting various statistics when implementing high-dimensional configurations. However, some instabilities were observed, likely tied to the mathematical designs of the methods, informing that some multivariate bias correction methods are incompatible with high-dimensional configurations highlighting the potential for further improvements in the field, as well as the importance of proper selection of the correction method specific to the needs of the user.

• Journal of Environmental Science International
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• v.32 no.6
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• pp.429-440
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• 2023

Quantitative habitat model is established with species occurrence and spatial abundance data, which were usually acquired by professional field ecologists and citizen scientists. The importance of citizen science data is increasing, but the quality of these data needs to be evaluated. This study aims to identify and compare both expert-based data and citizen science data based on the performance power of quantitative models derived from both data sets. A Maximum Entropy (MaxENT) model was developed using eight environmental variables, including climate, topography, landcover and distance to forest edge. The AUC values derived from the MaxENT model were 0.842 and 0.809, respectively, indicating a high level of explanatory power. All environmental variables has similar values for both data sets, except for the distance to forest edge and rice paddy, which was relatively higher for expert-based survey data than that of the citizen science data as the distances increased. This result suggests that habitat model derived from expert-based survey data shows more ecological niche including wider ranges from forest edges and isolated habitat patches of rice paddy. This is presumably because citizen scientists focuses on direct observation methods, whereas professional field surveys investigate a wider variety of methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.268-268
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• 2021

Groundwater resource is mostly used in Abomey-calavi (southern region of Benin) as main source of water for domestic, industrial, and agricultural activities. Groundwater intake across the region is not perfectly controlled by a network due to the presence of many private boreholes and traditional wells used by the population. After some decades, this important resource is becoming more and more vulnerable and needs more attention. For a better groundwater management in the region of Abomey-calavi, the present study attempts to predict a future probable groundwater drought using Recurrent Neural Network (RNN) for future groundwater level prediction. The RNN model was created in python using jupyter library. Six years monthly groundwater level data was used for the model calibration, two years data for the model test and the model was finaly used to predict two years future groundwater level (years 2020 and 2021). GRI was calculated for 9 wells across the area from 2012 to 2021. The GRI value in dry season (by the end of March) showed groundwater drought for the first time during the study period in 2014 as severe and moderate; from 2015 to 2021 it shows only moderate drought. The rainy season in years 2020 and 2021 is relatively wet and near normal. GRI showed no drought in rainy season during the study period but an important diminution of groundwater level between 2012 and 2021. The Pearson's correlation coefficient calculated between GRI and rainfall from 2005 to 2020 (using only three wells with times series long period data) proved that the groundwater drought mostly observed in dry season is not mainly caused by rainfall scarcity (correlation values between -0.113 and -0.083), but this could be the consequence of an overexploitation of the resource which caused the important spatial and temporal diminution observed from 2012 to 2021.

• The Journal of Sustainable Design and Educational Environment Research
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• v.22 no.4
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• pp.1-8
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• 2023

The downsizing of schools is accelerating due to a rapid decline in the school-age population, and as the crisis over regional and school disappearance increases, the need for smaller schools to respond to future educational needs is increasing. Through flexible curricula and digital/artificial intelligence-based classroom teaching improvements, students' satisfaction with school life, student creativity and character development, improved academic achievement, and strengthened cooperative communication capabilities will be observed, and teachers' teaching and learning methods will change. Educational effects such as these are important, and transforming school facilities into future-oriented spaces, including school space innovation, is required to accomplish them. This study examined the future of education systems in small schools, focusing on analyzing the educational effects and awareness of the sustainability of spatial innovation, in terms of school space changes, school education correlation, and smart environment, to develop innovation projects in small schools. A desirable direction for implementation is presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.231-240
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• 2024

Titanium dioxide (TiO₂) holds significant scientific and technological relevance as a key photocatalyst and resistive random-access memory, demonstrating unique physicochemical properties and serving as an n-type semiconductor. Understanding the density and arrangement of oxygen vacancies (VOs) is crucial for tailoring TiO₂'s properties to diverse technological needs, driving increased interest in exploring oxygen vacancy complexes and superstructures. In this mini review, we summarize the recent understandings of the fundamental properties of oxygen vacancies in bulk rutile (R-TiO₂) and anatase (A-TiO₂) based on DFT and beyond method. We specifically focus on the excess electrons and their spatial arrangement of disordered single VO in bulk R and A-TiO₂, aligned with the experimental findings. We also highlight the theoretical works on investigating the geometries and stabilities of ordered VOs complexes in bulk TiO₂. This comprehensive review provides insights into the fundamental properties of excess electrons in reduced TiO₂, offering valuable perspectives for future research and technological advancements in TiO₂-based devices.

• Journal of the Korean Institute of Rural Architecture
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• v.26 no.2
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• pp.47-56
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• 2024

Through an examination of future societal development, it was found that the demographic structure is gradually aging, thus placing higher demands on elderly welfare centers. This study conducted surveys on three elderly day care centers in the entire region, aiming to enhance the pivotal role of elderly day care centers in the welfare facilities for the elderly. The current usage status, interior architectu/ral evaluations, and questionnaire surveys of these centers were analysed. The results of investigation into the architectural environment of the elderly day care centers showed that in terms of physical environment, smaller-scale centers did not lag behind larger ones in internal facilities, but larger-scale centers excelled in spatial utilization. Furthermore, the results of questionnaire survey results revealed correlations between family relationships, health status, level of assistance required, and satisfaction with facility usage, while no correlation was found between usage time, health status, and satisfaction with facility usage. This study conducted basic investigations such as architectural and physical surveys, and questionnaire surveys on elderly day care centers. Based on the survey results, future design practices should continuously explore and innovate to meet the needs of an aging society, further improve the community care system, provide more comprehensive and meticulous services for the elderly, and lay the foundation for enhancing the quality of life for the elderly and providing comfortable services.