• The Journal of Bigdata
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• v.7 no.2
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• pp.31-41
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• 2022

Steel is one of the most fundamental components to mechanical industry. However, the quality of products are greatly impacted by the surface defects in the steel. Thus, researchers pay attention to the need for surface defects detector and the deep learning methods are the current trend of object detector. There are still limitations and rooms for improvements, for example, related works focus on developing the models but don't take into account real-time application with practical implication on industrial settings. In this paper, a real-time application of steel surface defects detection based on YOLOv4 is proposed. Firstly, as the aim of this work to deploying model on real-time application, we studied related works on this field, particularly focusing on one-stage detector and YOLO algorithm, which is one of the most famous algorithm for real-time object detectors. Secondly, using pre-trained Yolov4-Darknet platform models and transfer learning, we trained and test on the hot rolled steel defects open-source dataset NEU-DET. In our study, we applied our application with 4 types of typical defects of a steel surface, namely patches, pitted surface, inclusion and scratches. Thirdly, we evaluated YOLOv4 trained model real-time performance to deploying our system with accuracy of 87.1 % mAP@0.5 and over 60 fps with GPU processing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.109-117
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• 2023

Schedule delays present a major risk factor, as they can adversely affect construction projects, such as through increasing construction costs, claims from a client, and/or a decrease in construction quality due to trims to stages to catch up on lost time. Risk management has been conducted according to the importance and priority of schedule delay risk, but quantification of risk on the depth of schedule delay tends to be inadequate due to limitations in data collection. Therefore, this research used the BERT (Bidirectional Encoder Representations from Transformers) language model to convert the contents of aconstruction log, which comprised unstructured data, into WBS (Work Breakdown Structure)-based structured data, and to form a model of classification and quantification of risk. A process was applied to eight highway construction sites, and 75 cases of rain schedule delay risk were obtained from 8 out of 39 detailed work kinds. Through a K-S test, a significant probability distribution was derived for fourkinds of work, and the risk impact was compared. The process presented in this study can be used to derive various schedule delay risks in construction projects and to quantify their depth.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.71-83
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• 2009

Shotcrete is an important primary support for tunnelling in rock. The quality control of shotcrete is a core issue in the safe construction and maintenance of tunnels. Although shotcrete may be applied well initially onto excavated rock surfaces, it is affected by blasting, rock deformation and shrinkage and can debond from the excavated surface, causing problems such as corrosion, buckling, fracturing and the creation of internal voids. This study suggests an effective non-destructive evaluation method of the tunnel shotcrete bonding state applied onto hard rocks using the impact-echo (IE) method and ground penetration radar (GPR). To verify previous numerical simulation results, experimental study carried out. Generally, the bonding state of shotcrete can be classified into void, debonded, and fully bonded. In the laboratory, three different bonding conditions were modeled. The signals obtained from the experimental IE tests were analyzed at the time domain, frequency domain, and time-frequency domain (i.e., the Short- Time Fourier transform). For all cases in the analyses, the experimental test results were in good agreement with the previous numerical simulation results, verifying this approach. Both the numerical and experimental results suggest that the bonding state of shotcrete can be evaluated through changes in the resonance frequency and geometric damping ratio in a frequency domain analysis, and through changes in the contour shape and correlation coefficient in a time-frequency analysis: as the bonding state worsens in hard rock condition, the autospectral density increases, the geometric damping ratio decreases, and the contour shape in the time-frequency domain has a long tail parallel to the time axis. The correlation coefficient can be effectively applied for a quantitative evaluation of bonding state of tunnel shotcrete. Finally, the bonding state of shotcrete can be successfully evaluated based on the process suggested in this study.

• Journal of Korea Planning Association
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• v.54 no.3
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• pp.27-48
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• 2019

The government has implemented housing welfare policy to ease low-income households' housing-cost burden and improve their quality of life. However, public housing residents and housing choice voucher recipients still show a high level of housing-cost burden. In this regard, this study aims to provide policy implications for current housing welfare policy by analyzing and comparing the factors that determine both subsidized and unsubsidized households' housing-cost burden. For the empirical analysis, this study uses "2017 Korea Housing Survey" and divides groups into public housing residents, housing choice voucher recipients, and unsubsidized low-income renters. We compared the level of housing-cost burden by employing t-test and chi-squared analyses and the factors affecting the housing-cost burden by employing logistic regression analyses between the three groups. According to the empirical analysis, the housing cost is the most burdensome for the housing choice voucher recipients group, followed by the unsubsidized low-income renters and public housing residents. In addition, the factors affecting housing-cost burden are different between the three groups. In case of public housing residents, housing characteristics usually affect the housing-cost burden. For housing choice voucher recipients and unsubsidized low-income renters, both housing and household characteristics influence the housing-cost burden. Looking at the detailed factors, except for the housing tenure and regional average rents that are common factors for all groups, the amount of deposit is an important factor for public housing residents, and household employment status is an important factor for both housing choice voucher recipients and unsubsidized low-income renters. The policy implications of this study are as follows: First, it is necessary to review the blind spot of the current housing welfare policy. Second, a comprehensive review of the housing choice voucher program is required. Third, it is necessary to make policy efforts to ease the level of housing-cost burden for renters. Fourth, a program is needed for those public housing residents who need a deposit support. Fifth, there should be further assistance with public housing for the poorest people.

• Journal of Korea Entertainment Industry Association
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• v.13 no.6
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• pp.155-163
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• 2019

The purpose of this study was to compare and analyze life habits and senior fitness according to metabolic syndrome by sex and age in the elderly and prevent metabolic syndrome in the elderly. A questionnaire survey for life habits and senior fitness measurement were conducted with 159 old men and 233 old women(a total of 392) who used welfare facilities for the elderly located in G Metropolitan City. The results were as follows. 1. In the comparison of life habits according to metabolic syndrome by sex and age, while old men showed a significant difference in smoking, drinking and drug intake, and stress relief, old women showed a significant difference in drinking and drug intake and dietary habits. 2. In the comparison of senior fitness according to metabolic syndrome by sex and age, while old men had a significant difference in lower and upper body muscle strength, old women had a significant difference in lower and upper body muscle strength, and general endurance. Based on the findings, the elderly's life habits according to metabolic syndrome had a difference in smoking, drinking and drug, and dietary life and senior fitness had a significant difference in muscle strength, flexibility, and endurance. Thus, the elderly need the methods for exercise habits and stress relief for healthy life. Also, old men should steadily strive to improve flexibility, endurance, agility, and balance and old women should steadily strive to improve agility and balance. When the elderly are careful for decreased fitness with age and strive to maintain healthy life habits, their quality of life will be improved and metabolic syndrome will be prevented.

• 한국노년학
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• v.29 no.3
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• pp.1159-1182
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• 2009

The purpose of this study is to examine everyday emotional experience of urban elderly in Korea. Specifically, this study explores gender differences in the effect of place/location of activity and companionship on the daily emotional experience. Data were collected from 148 urban elderly (men=76, women=72) in Seoul, using Experience Sampling Method(ESM). The unit of analysis was the self-report and in total 5,530 self-reports were provided. The statistical methods used for the data analyses were descriptive statistics, t-test, χ² verification, and ANOVA. The major findings are as follows. First, the elderly in Korea spend a quite substantial portion of their time at home, and they spend the largest share of their time in company with their spouse. Second, women report higher intensity of stress and irritation than men in terms of overall emotional experience. Third, the effect of activity location and companionship on emotional experience turned out to be different depending on gender. Emotional experience of daily lives and overall quality of life are shown to be inter-related. Based on these findings, this study provides a significant implication that situational contexts of experience should be considered in order to understand the daily emotional experience of the contemporary Korean elderly.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.272-278
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• 2023

Attention, an important element of human cognitive function, is an important cognitive function that focuses only on necessary stimuli from various stimuli through sensory systems. Although various studies have shown that environmental conditions may affect the level of attention, the effect on attention by applying cooling directly to the skin has not been studied much. Differences in attention depending on when and whether cryotherapy was applied during learning and relaxation activities were examined among 36 subjects. The FAIR attention test, a visual attention evaluation tool, was used, and statistical analysis was conducted on the results of the sub-index of FAIR: Performance index, Quality index, and Continuity index. Among participants who performed rest activities, the application of cryotherapy appeared to have no effect on any subindex. Among the participants who performed learning activities, the group that applied pre-cryotherapy (P=469.0, C=435.4)) and the group that applied post-cryotherapy (P=457.4, C=425.4) showed higher Performance index and Continuity index than the group that did not apply cryotherapy (P=335.8, C=301.7). From these results, it can be concluded that cryotherapy maintains the level of alertness and awakens attention, albeit to a limited extent.

• Journal of Korean Elementary Science Education
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• v.42 no.4
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• pp.497-512
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• 2023

While scientific explanation is a fundamental component of science, teachers often lack familiarity with the formal structure of scientific explanations and the criteria for assessing their quality. Consequently, this study aims to clarify the concept of scientific explanation and proposes a tool for constructing scientific explanations. The primary objective is to explore the tool's impact on enhancing the explanatory skills of pre-service teachers when it comes to the phenomenon of condensation. The research findings indicate that many pre-service teachers initially operated at a description level during the pre-test. However, the implementation of the tool enabled them to advance their explanatory skills beyond the associative level. Notably, the tool was analyzed for its ability to provide pre-service teachers with a conceptual framework for explaining phenomena and guiding logical explanations and micro-level interpretations. This study holds significance in demonstrating that pre-service teachers can comprehend the formalities and criteria of scientific explanations and apply them to enhance their own explanatory abilities. Moving forward, efforts should be made to enhance the scientific explanation level among pre-service teachers across various topics and subject areas. Furthermore, pre-service teachers need classroom experiences that foster the construction of scientific explanations in authentic contexts.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.62-62
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• 2020

Ginseng is a shade-plant cultivated using shading facilities. However, at too low light levels, root growth is poor, and at high light levels, the destruction of chlorophyll reduces the photosynthesis efficiency due to leaf burn and early fall leaves. The ginseng has a lightsaturation point of 12,000~15,000 lux when grown at 15 to 20℃ and 9,500 lux at 25℃. This study was conducted to select the optimal light intensity of 3-year-old ginseng grown in blue-white film plastic house. The seeds were planted in the blue-white film plastic house with different light receiving rate (March 17, 2020). Between April and September, the average air temperature in the house was 20.4-20.7℃. Average soil temperature was 18.3℃-18.5℃. The chemical properties of the test soil was as follows. The pH level was 7.0-7.4, EC was 0.5-0.6 dS/m, OM was at the levels of 33.6-37.7 g/kg, P₂O₅ was 513.0-590.8 mg/kg, slightly higher than the allowable 400 mg/kg. The amount of light intensity, illuminance, and solar radiation in the blue-white film house was increased as the light-receiving rate increased and the amount of light intensity was found to be 9-14% compared to the open field, 8-13% illuminance and 9-14% solar irradiation respectively. The photosynthesis rate was the lowest at 3.1 µmolCO²/m²/s in the 9% light blue-white plastic house and 4.2 and 4.0 µmolCO²/m²/s in the 12% and 14% light blue-white plastic house, respectively. These results generally indicate that the photosynthesis of plants increases with the amount of light, but the ginseng has a lower light saturation point at high temperatures, and the higher the amount of light, the lower the photosynthetic efficiency. The SPAD (chlorophyll content) value decreased as the increase of light-receiving rate, and was the highest at 32.7 in 9% light blue-white plastic house. Ginseng germination started on April 11 and took 13-15 days to germinate. The overall germination rate was 82.9-85.8%. The plant height and length of stem were long in the 9% light-receiving plastic house. The diameter of stem was thick in the 12-14% light-receiving plastic house. In the 12% and 14% light-receiving plastic house, the length and diameter of taproot was long and thick, so the fresh weight of root per plant was 20 g or more, which was heavier than 16.9 g of the 9% light-receiving plastic house. The disease incidence (Alternaria blight, Gray mold and Damping-off etc.) rate were 0.9-2.7%. The incidence of Sclerotinia rot disease was 7.5-8.4%, and root rot was 0-20.0%. The incidence ratio of rusty root ginseng was 34.4-38.7% level, which was an increase from the previous year's 15% level.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.85-96
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• 2023

In a reality where negative perceptions and social prejudices towards individuals with mental illnesses persist, the absence and lack of social support systems acquired through personal intimate social networks can be considered a significant hindrance to the quality of life for those with mental disorders. Therefore, this study examined the impact of the characteristics of social networks and social support on the life satisfaction of individuals with mental illnesses. A survey was conducted with 180 patients from seven mental health treatment facilities in the Daegu area. The data were analyzed using MANOVA, hierarchical multiple regression analysis, and Sobel test for mediation analysis with SPSS 25 software. The key findings of the study revealed that the intimacy aspect of social networks had a positive and significant effect on social support and life satisfaction. On the other hand, the size of the social network showed a negative influence on social support. Furthermore, social support partially mediated the relationship between the intimacy of social networks and life satisfaction, and it fully mediated the relationship between the size of social networks and life satisfaction. Based on these research outcomes, practical and policy-related recommendations are provided to enhance life satisfaction through increased social support for this population.