• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.1
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• pp.55-65
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• 2024

This study aimed to assess the accuracy of tooth widths, intermolar widths, and arch lengths acquired through two intraoral scanners, including iTero Element Plus Series (Align Technology, Santa Clara, CA, USA) and Trios 4 (3Shape, Copenhagen, Denmark), specifically on mixed dentition. A total of 30 subjects were divided into 2 groups, each undergoing both alginate impressions and intraoral scanning using either the iTero or Trios scanner. The plaster models were measured with a caliper, while the digital models were measured virtually. In the iTero group, all tooth width measurements exhibited differences compared to the plaster values, except for maxillary left lateral incisors (p = 0.179), mandibular right (p = 0.285), and left (p = 0.073) central incisors. The Trios group did not display significant differences in any of the tooth width measurements. Intermolar width comparisons for both groups indicated differences, except for mandibular primary canine to primary canine values (p = 0.426) in the iTero group. Regarding arch length, the mandibular anterior, maxillary right, and left arch lengths in the iTero group demonstrated larger caliper values than those of iTero. Conversely, in the Trios group, all parameters showed smaller caliper values, especially in upper anterior, maxillary right, mandibular right, and mandibular left arch lengths with significance (p = 0.027, 0.007, 0.003, and 0.047, respectively). Despite the differences between the two groups, digital models might be clinically suitable alternatives for plaster models. Pediatric dentists should carefully assess these differences, as a comprehensive evaluation would result in precise orthodontic treatment planning and favorable outcomes for young patients with mixed dentition.

• KIPS Transactions on Computer and Communication Systems
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• v.13 no.1
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• pp.10-20
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• 2024

As the online commerce market continues to expand with an increase of diverse products and content, users find it challenging in navigating and in the selection process. Thereafter both platforms and shopping malls are actively working in conducting continuous research on recommendations system to select and present products that align with user preferences. Most existing recommendation studies have relied on user data which is relatively easy to obtain. However, these studies only use a single type of event and their reliance on time dependent data results in issues with reliability and complexity. To address these challenges, this paper proposes a recommendation system that analysis user preferences in consideration of the relationship between various types of event data. The proposed recommendation system analyzes the correlation of multiple events, extracts weights, learns the recommendation model, and provides recommendation services through it. Through extensive experiments the performance of our system was compared with the previously studied algorithms. The results confirmed an improvement in both complexity and performance.

• Steel and Composite Structures
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• v.50 no.4
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• pp.383-401
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• 2024

The research comprehensively studies the axial compression performance of T-shaped concrete-filled thin-walled steel tubular (CTST) long columns after fire exposure. Initially, a series of tests investigate the effects of heating time, load eccentricity, and stiffeners on the column's performance. Furthermore, Finite Element (FE) analysis is employed to establish temperature and mechanical field models for the T-shaped CTST long column with stiffeners after fire exposure, using carefully determined key parameters such as thermal parameters, constitutive relations, and contact models. In addition, a parametric analysis based on the numerical models is conducted to explore the effects of heating time, section diameter, material strength, and steel ratio on the axial compressive bearing capacity, bending bearing capacity under normal temperature, as well as residual bearing capacity after fire exposure. The results reveal that the maximum lateral deformation occurs near the middle of the span, with bending increasing as heating time and eccentricity rise. Despite a decrease in axial compressive load and bending capacity after fire exposure, the columns still exhibit desirable bearing capacity and deformability. Moreover, the obtained FE results align closely with experimental findings, validating the reliability of the developed numerical models. Additionally, this study proposes a simplified design method to calculate these mechanical property parameters, satisfying the ISO-834 standard. The relative errors between the proposed simplified formulas and FE models remain within 10%, indicating their capability to provide a theoretical reference for practical engineering applications.

• Journal of Korean Association for Spatial Structures
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• v.24 no.2
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• pp.31-41
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• 2024

This study aims to investigate the seismic response of a large span thin shell structures and assess their displacement under seismic loads. The study employs finite element analysis to model a thin shell structure subjected to seismic excitation. The analysis includes eigenvalue analysis and time history analysis to evaluate the natural frequencies and displacement response of the structure under seismic loads. The findings show that the seismic response of the large span thin shell structure is highly dependent on the frequency content of the seismic excitation. The eigenvalue analysis reveals that the tenth mode of vibration of the structure corresponds to a large-span mode. The time history analysis further demonstrates, with 5% damping, that the displacement response of the structure at the critical node number 4920 increases with increasing seismic intensity, reaching a maximum displacement of 49.87mm at 3.615 seconds. Nevertheless, the maximum displacement is well below the allowable limit of the thin shell. The results of this study provide insight into the behaviour of complex large span thin shell structures as elevated foundations for buildings under seismic excitation, based on the displacement contours on different modes of eigenvalues. The findings suggest that the displacement response of the structure is significant for this new application of thin shell, and it is recommended to enhance the critical displacement area in the next design phase to align with the findings of this study to resist the seismic impact.

• Korean Journal of Community Nutrition
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• v.29 no.1
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• pp.16-33
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• 2024

Objectives: The purpose of this study was to examine mothers' knowledge levels on complementary foods and their perception of convenience complementary foods. Methods: An online survey was conducted with mothers aged 20-49 years who had purchased convenience complementary foods and had a preschool child aged 4 months or older. The respondents were categorized into 3 groups based on their knowledge scores: low- (0-50 points), mid- (55-65 points), and high- (70-100 points) knowledge groups. Results: The average score of mothers' knowledge on complementary foods was 58.8 out of 100 points. Working mothers were found to have lower levels of knowledge compared to mothers who were housewives. Only 1/4 of responding mothers had educational experience on complementary foods. Mothers expressed a desire for information on the types of complementary foods (72.2%) and the intake amounts (60.3%) corresponding to each phase of their child's development. Multivariate analysis of variance revealed significant differences in health (P = 0.002), variety (P = 0.039), and hygiene (P = 0.041) among the factors taken into consideration when purchasing convenience complementary foods according to the mothers' knowledge levels. Mothers in the high-knowledge group placed a greater importance on 'balanced nutrition' (P = 0.022) and 'hygienic cooking' (P = 0.010) compared to mothers in the low-knowledge group. The results of the modified importance-performance analysis, which compared the importance and performance of the factors taken into consideration when purchasing convenience complementary foods, highlighted the need for efforts in 'health,' 'hygiene,' and 'price,' while also indicating an excessive effort in 'convenience.' Conclusions: This study suggests expanding relevant education programs to enhance mothers' knowledge on complementary foods, especially for working mothers. In the industry, marketing strategies for complementary food products could be developed that align with the needs of mothers, focusing on health, hygiene, and price.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.363-373
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• 2023

Numerous studies have established a correlation between sociodemographic characteristics and water usage, identifying population as a primary independent variable in mid- to long-term demand forecasting. Recent dramatic sociodemographic changes, including urban concentration-rural depopulation, low birth rates-aging population, and the rise in single-person households, are expected to impact water demand and supply patterns. This underscores the necessity for operational and managerial changes in existing water supply systems. While sociodemographic characteristics are regularly surveyed, the conducted surveys use aggregate units that do not align with the actual system. Consequently, many water demand forecasts have been conducted at the administrative district level without adequately considering the water supply system. This study presents an upward water demand forecasting model that accurately reflects real water facilities and consumers. The model comprises three key steps. Firstly, Statistics Korea's SGIS (Statistical Geological Information System) data was reorganized at the DMA level. Secondly, DMAs were classified using the SOM (Self-Organizing Map) algorithm to consider differences in water facilities and consumer characteristics. Lastly, water demand forecasting employed the PCR (Principal Component Regression) method to address multicollinearity and overfitting issues. The performance evaluation of this model was conducted for DMAs classified as rural areas due to the insufficient number of DMAs. The estimation results indicate that the correlation coefficients exceeded 0.9, and the MAPE remained within approximately 10% for the test dataset. This method is expected to be useful for reorganization plans, such as the expansion and contraction of existing facilities.

• Resources Recycling
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• v.33 no.2
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• pp.46-53
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• 2024

The residual heat and high CaO content present in the slag remaining in the ladle after the completion of continuous casting in the electric arc furnace (EAF) steelmaking process have been utilized to reduce power consumption and lime usage in the ladle furnace (LF) process. However, if the timing of such processes does not align with the LF and continuous casting operations, the recycling rate will decrease. To increase the slag recycling rate, the effect of ladle slag recycling methods, specifically pouring ladle slag into the slag pot in advance for subsequent recycling, on LF operations was analyzed. The slag liquefaction rate was calculated using the thermodynamic program Factsage 8.3 for ladle molten slag recycling methods. By applying each of the 10 heats operations for the ladle slag recycling methods, the desulfurization ability and LF operation performance were compared. It was found that when slag was immediately recycled into the ladle after continuous casting was completed, power consumption decreased by 0.3 MWh, LF operation time was shortened by 1.2 minutes, and the desulfurization rate increased by 5.8%.

• The Research Journal of the Costume Culture
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• v.32 no.2
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• pp.287-298
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• 2024

Clothing is intimately intertwined with daily lives as every individual relies on it. The pervasive issue of plagiarism in the fashion industry has led to an increased demand to protect intellectual property rights. Currently, studies on the protection of fashion design intellectual property rights in China remain in the exploratory stage and warrant further investigation. This paper addresses the issue in two parts. The first part contains an analysis of the theoretical foundation for the protection of fashion design copyrights. It is further divided into three subsections. The first subsection primarily examines the concept of copyrights and laws. The second subsection focuses on the concept of fashion design copyrights and laws. The third subsection analyzes copyright laws concerning fashion designs in China. The second section offers an analysis of infringement cases involving fashion designs published during the Baiyi Cup Intellectual Property Case Summary Writing Competition held in China in 2023. It outlines the shortcomings of the current Chinese copyright laws regarding the protection of fashion designs, and proposes measures for improvement. This study argues that the institutional framework for intellectual property rights in the Chinese fashion industry should align with practical considerations and explores suitable legal regulations and how they relate to specific circumstances in China. Besides refining the legal framework, fashion designers and enterprises must take measures to entablish the intellectual property rights of their clothing brands.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.6
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• pp.205-220
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• 2023

This study aimed to analyze the needs and interests of the public on endangered wildlife using complaint big data. We collected 1,203 complaints and their corresponding text data on endangered wildlife, pre-processed them, and constructed a document-term matrix for 1,739 text data. We performed LDA (Latent Dirichlet Allocation) topic modeling and network analysis. The results revealed that the complaints on endangered wildlife peaked in June-August, and the interest shifted from insects to various endangered wildlife in the living area, such as mammals, birds, and amphibians. In addition, the complaints on endangered wildlife could be categorized into 8 topics and 5 clusters, such as discovery report, habitat protection and response request, information inquiry, investigation and action request, and consultation request. The co-occurrence network analysis for each topic showed that the keywords reflecting the call center reporting procedure, such as photo, send, and take, had high centrality in common, and other keywords such as dung beetle, know, absence and think played an important role in the network. Through this analysis, we identified the main keywords and their relationships within each topic and derived the main issues for each topic. This study confirmed the increasing and diversifying public interest and complaints on endangered wildlife and highlighted the need for professional response. We also suggested developing and extending participatory conservation plans that align with the public's preferences and demands. This study demonstrated the feasibility of using complaint big data on endangered wildlife and its implications for policy decision-making and public promotion on endangered wildlife.

• Journal of Korean Critical Care Nursing
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• v.17 no.2
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• pp.25-41
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• 2024

Purpose : This study aimed to investigate changes in critical nursing activities from 2009 to 2020 and explore the relationship between nurse staffing and such activities in intensive care units. Methods : A total of 446,445 adult patients admitted to intensive care units in tertiary and general hospitals from 2009 to 2020 were identified using the National Health Insurance claims database. The Critical Nursing Activities Index was calculated based on the following critical nursing activities: ventilator, extracorporeal membrane oxygenation (ECMO), and continuous renal replacement therapy (CRRT). Trend analysis was performed to analyze changes in critical nursing activities over 12 years and to assess linear trends across different staffing levels. Results : The annual utilization days for ventilators, ECMO, and CRRT, as well as the Critical Nursing Activities Index significantly increased over the study period (p-for-trend<.001) in tertiary and general hospitals, except for ventilator use in general hospitals. Ventilator, ECMO, and CRRT utilization exhibited a significant upward trend with higher nurse staffing levels (Bonferroni adjusted p-for-trend<.001). The Critical Nursing Activities Index was significantly higher in hospitals with higher staffing levels compared to those with lower staffing levels (Bonferroni adjusted p <.05). Conclusion : The findings underscore the need for improved nurse staffing levels in intensive care units. Government policies should ensure that staffing levels align with critical nursing activities among critically ill patients to uphold the quality of care.