• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.167-174
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• 2022

The objective of this study is to evaluate the dynamic properties of DUS (damping-up system) composed of the materials with excellent damping capacity, and to compare with those of the conventional hangar bolt. The main parameters are the type and hardness (𝜂_H), of rubber and the prestress force (value converted from the compression strain (𝜂_R) in the stress-strain relationship of rubber). The dynamic properties were examined from the natural frequency (𝜔_n), maximum response acceleration (A_m), amplification coefficient (𝛼_p), maximum relative displacement (𝚫_m), and damping ratio (𝜉_D). The test results showed that the A_m, 𝛼_p, and 𝚫_m values of DUS were 46.3%, 46.6% and 62.9% lower, respectively, and the 𝜉_D value was 3.89 times higher, when compared to those of the conventional hangar bolt. In particular, the 𝛼_p value was 1.3 for DUS, and 2.45 for the conventional hanger bolt, which were similar to those of rigid and flexible components specified in KDS 41 17 00, respectively. Consequently, in the optimal details of DUS, the 𝜂_H values of 50 and 45 were required for the NR (natural rubber) and EPDM (ethylene propylene diene monomer), and the 𝜂_R value of 5% was also recommended.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.587-592
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• 2021

Change in the cortical thickness of long bones occurring with aging and osteoporosis is known to be a risk factor for fracture. The present study aims to investigate the dependencies of phase velocities of ultrasonic guided waves on the cortical thickness in 7 soft tissue-bone mimicking phantoms consisting of acrylic plates covered by a 2 mm-thick silicone rubber layer by using the axial transmission technique with a pair of transducers with a center frequency of 200 kHz and a diameter of 12.7 mm. Two distinct propagating waves with different velocities, the First Arriving Signal (FAS) and the Slow Guided Waved (SGW), were consistently observed for all the soft tissue-bone mimicking phantoms. The FAS velocity decreased slightly with increasing thickness, whereas the SGW velocity increased strongly with increasing thickness. The FAS and the SGW velocities were found to be closely consistent with the S0 and the A0 Lamb mode velocities for a free acrylic plate, respectively, suggesting that the presence of the soft tissue mimicking material (2 mm-thick silicone rubber layer) covering the acrylic plates does not influence significantly the velocity measurements.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.653-664
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• 2021

As the construction standards for energy-saving eco-friendly housing have recently been strengthened, the proportion of window work has increased with the demand for high-efficiency housing. Windows have high frequency of use, and there is the potential for many defects to occur depending on the characteristics of construction. According to a government agency's survey of defects in public rental apartment housing, defects in the windows work accounted for the highest portion of complaints received. Accordingly, related previous studies were considered, and it was found that the existing studies in Korea lacked research that reflected the construction characteristics of window work and the importance of maintenance. In addition, existing overseas studies considered both the constructor and the resident's position, considering the cost aspect together, and showed a trend of structuring the relationship between defects and causes. Therefore, this study will analyze the causes of defects that can occur in the construction phase of the windows work, reflect the construction characteristics, and derive major factors that consider the importance of maintenance based on the possibility of recurrence after repairing defects. Ultimately, this research will contribute to preventing defects in the construction phase and reducing maintenance costs by presenting a highly effective defect management plan through selecting the major factors for each defect type that can be intuitively judged by analyzing the causal relationship between defect types and causes.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.3
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• pp.5-26
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• 2022

The purpose of this study is to analyze high school students' understanding and use of the recommended books lists. The survey distributed to high school students in seven high schools located in Seoul, and 311 students responded. Using SPSS 24, the data was analyzed by frequency, binary logistic model, and one-way ANOVA. Results show the followings. First, the meaningful factors affecting students' use of recommended books lists are gender, grade levels, and the degree to which students think recommended books lists include the books that are suitable and interesting. Particularly, the degree to which students think recommended books lists include the suitable books for them is the strong factor affecting students' use of the recommended books lists. Second, male students are less likely to use recommended books lists than female students. Male students consistently are less likely to use the recommended books lists made by school librarians, subject teachers, and reading experts and/or organizations. Third, teacher-librarians believed that the recommended books lists would help students who do not enjoy reading and have difficulties in reading. However, the study finds that students who enjoy reading and read well are more willing to use the recommended books lists made by school librarians, subjects teachers, and reading experts and/or organizations than those who do not. Fourth, students are most willing to use the recommended books lists for college preparation. The findings suggest the further research topics in designing the recommended books lists suitable for high school students and in scaffolding the high school students' use of book information reflected in recommended books lists.

• Journal of Internet of Things and Convergence
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• v.8 no.4
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• pp.85-96
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• 2022

The purpose of this study was to investigate how the management strategies and organizational culture required in the digital economy have an effect on business performance. It provided basic data on management strategies and organizational culture necessary to approach as a digital leading country. For data collection, a survey was conducted from March 1 to May 30, 2022 for companies located in J province and engaged in industries related to the digital economy. The survey was conducted online and non-face-to-face, and a total of 225 companies participated in the survey. For statistical analysis, frequency analysis, exploratory factor analysis and reliability analysis, cluster analysis, independent sample t-test, and multiple regression analysis were performed. The research results are as follows. First, organizational culture was classified into high and low groups according to preference in innovation oriented, relationship oriented, task oriented, and hierarchical oriented. Second, the 4 types of organizational culture showed differences in prospectors strategy, analyzers strategy, defenders strategy, differentiation strategy, cost leadership strategy, financial performance, and non-financial performance according to preference. Third, management strategies affecting financial performance were found to be analyzers strategy, differentiation strategy, prospectors strategy, and cost leadership strategy. Fourth, management strategies affecting non-financial performance were found to be differentiation strategy, defenders strategy, analysis strategy, offensive strategy, cost leadership strategy, and focus strategy. Fifth, organizational culture affecting financial performance was found to be task oriented. Sixth, organizational culture affecting non-financial performance was found to be innovation oriented and relationship oriented. Through these studies, it is expected that the economy will be revitalized in the domestic market and a growth ecosystem that can take a new leap forward is created in the global market.

• Journal of Food Hygiene and Safety
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• v.37 no.4
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• pp.238-248
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• 2022

This study was conducted to evaluate the safety of 208 types of residue pesticides on 150 dried agricultural products in Ulsan. The pesticide residues were detected using GC-MS/MS, LC-MS/MS, GC/ECD, GC/NPD, and LC/PDA. The detection rate was 19.3% (29 of 150 samples), and 28 types of pesticides were detected. Two of the 29 pesticide residues exceeded the maximum residue limit (MRL). Difenoconazole was detected in Ulleungdo aster, and chlorothalonil and chlorpyrifos were detected in chili pepper leaves. In the vegetable group, the frequency of pesticide residues was found to be the highest in dried leafy vegetables, followed by dried fruiting vegetables other than cucurbit vegetables, and then dried stalk and stem vegetables. The pesticide types detected in the commercial dried agricultural products were fungicide (60%), insecticide (23.8%), and acaricide (16.3%). In the validation study, the values of limit of detection (LOD), limit of quantitation (LOQ), coefficient of determination (R²), and recovery rate were in the range of 0.0001-0.0409 mg/kg, 0.0003-0.1241 mg/kg, 0.994-0.999, and 81.58-116.79%, respectively. The ratio of estimated daily intake (EDI)/acceptable daily intake (ADI) was 0.00002-0.31395%.

• Korean Journal of Plant Resources
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• v.36 no.1
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• pp.100-106
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• 2023

In order to control the fire blight disease, all plants within the radius of the diseased orchard were removed in the early stage of the outbreak, or antibiotics control was performed for prevention. Since the beginning of antibiotics use on plants, the potential for development of resistance to antibiotics by the plant pathogen and unintended detrimental effects on the fruit trees and environment has become a problem. The purpose of this study is to determine the degree of phytotoxicity to fruit trees caused by excessive spraying of the fire blight disease disinfectant and to establish basic data for safe disinfectant guide. We analyzed whether damage to the fruit tree and the maximum residual limit of fruit was exceeded when three kinds of the fire blight disease disinfectants were continuously sprayed in excess of the number of safe use during the growing season. There was no phytotoxicity in apple 'Fuji' and pear 'Niitaka', and oxolinic acid was detected beyond the limit of quantitation in 'Fuji' grown without a bag, and the other disinfectants were detected below the maximum residue limit. When these disinfectants are continuously sprayed in excess of the number of safe, phytotoxicity may remain on the fruit. Therefore, it is necessary to observe the prescribed dilution factor and observe the safe frequency and the timing of use.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.105-115
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• 2023

This study seeks to find a way to induce users to expand their direct participation in sports through the acceptance of digital technology. From July 1 to August 30, 2022, a survey was conducted targeting home training users who applied the Internet of Things (IoT). 129 people participated in the survey through non-face-to-face self-administration method. For data processing, frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, multiple regression analysis, and 3-step mediation regression analysis were conducted using IBM's SPSS 21.0 program. The results of the study are as follows. First, in the relationship between the home training PPM model and direct participation in sports, ease appeared to have a mediating effect. In the factors of push, simple functionality showed a complete mediating effect, and inefficiency showed a partial mediating effect. Among pull factors, enjoyment and possibility of experience showed a complete mediating effect. In the mooring factors, individual innovativeness showed a complete mediating effect. Second, in the relationship between home training PPM model and direct participation in sports, usefulness showed a mediating effect. In the factors of push, simple functionality showed a complete mediating effect, and inefficiency showed a partial mediating effect. Among pull factors, enjoyment and possibility of experience showed a complete mediating effect. Among the mooring factors, individual innovativeness showed a partial mediating effect. Through this research, it is expected that the sports industry will contribute to the expansion of consumption expenditure and economic growth through the expansion of digital technologies such as NFT, Metaverse, and virtual/augmented reality.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.451-470
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• 2023

Purpose: Since COVID-19 was first discovered in China in December 2019, it has rapidly spread around the world, causing serious economic and social problems not only in individuals' lives, but also in businesses and countries. Individuals, businesses, and governments have all made various efforts to prevent the spread of COVID-19. Although the roles of individuals, companies, and the government are important to respond to and manage infectious diseases, previous studies have only partially studied the roles. Therefore, in this study, the roles of individuals, companies, and the government to achieve results in responding to infectious diseases disaster management A comprehensive study was conducted on this issue, and it was attempted to understand the impact of workers' perceptions of infectious disease disaster management and government and corporate capabil]ities on disaster response performance. Method: The survey was conducted for workers in the automobile manufacturing industry in Ulsan, Gyeongju, and Yangsan, and frequency analysis, factor analysis, correlation analysis, and regression analysis were performed. Result: It was found that worker perception had a positive effect on both government and corporate capabilities as well as disaster management performance. In addition, government capacity and corporate capacity had a positive effect on disaster management performance. Conclusion: The results of this study are meaningful in that they reveal that not only workers' perceptions but also the capabilities of the government and companies are important to achieve disaster response performance. In addition, workers should make good use of opportunities for education and participation provided by the government and corporations, and make the most social efforts that workers can make.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.295-306
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• 2019

The purpose of this study was to Happiness Sharing Kumdo Class Participating Adolescents' achievement goal orientation on ego-resiliency and quality of life and to provide guidance measures for the correct growth of vulnerable participants through the happiness sharing Kumdo class, which will be activated as a sports support program. To achieve the purpose of this research, 236 Adolescent participating in the Happiness Sharing Kumdo Class was selected and surveyed in Seoul, Gyeonggi Province and Incheon. Based on the data collected, the following results were derived by conducting frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, and multiple regression analysis. First, verification of the effect of achievement goal orientation of Adolescent participating in Happiness Sharing Kumdo Class on ego-resiliency showed that task-orientation has significant influence on diversity, future-orientation, and emotion control, and ego-orientation has significant influence on diversity and emotion control. Second, verification of the effect of achievement goal orientation of Adolescent participating in Happiness Sharing Kumdo Class on quality of life showed that task-orientation has significant influence on quality of physical, psychological, social, environmental and educational quality, and ego-orientation has a significant influence on quality of physical and environmental quality. Third, verification of the effect of ego-resiliency on quality of life by Adolescent participating in Happiness Sharing Kumdo Class showed that diversity has not significant influence all factors of quality of life, but future-orientation has significant influence on quality of psychological and environmental quality, and emotion control has a significant influence on quality of physical, psychological, social and educational quality.