• Geomechanics and Engineering
• /
• 제24권3호
• /
• pp.215-226
• /
• 2021

To study the evolution mechanism of cracks in rocks with multiple defects, rock-like samples with multiple defects, such as strip-shaped through-going cracks and cavity groups, are used, and the crack propagation law and changes in AE (acoustic emission) and strain of cavity groups under different inclination angles are studied. According to the test results, an increase in the cavity group inclination angle can facilitate the initial damage degree of the rock and weaken the crack initiation stress; the initial crack initiation direction is approximately 90°, and the extension angle is approximately 75~90° from the strip-shaped through-going cracks; thus, the relationship between crack development and cavity group initiation strengthens. The specific performance is as follows: when the initiation angle is 30°, the cracks between the cavities in the cavity group develop relatively independently along the parallel direction of the external load; when the angle is 75°, the cracks between the cavities in the cavity group can interpenetrate, and slip can occur along the inclination of the cavity group under the action of the shear mechanism rupture. With the increase in the inclination angle of the cavity group, the AE energy fluctuation frequency at the peak stress increases, and the stress drop is obvious. The larger the cavity group inclination angle is, the more obvious the energy accumulation and the more severe the rock damage; when the cavity group angle is 30° or 75°, the peak strain of the local area below the strip-shaped through-going fracture plane is approximately three times that when the cavity group angle is 45° and 60°, indicating that cracks are easily generated in the local area monitored by the strain gauge at this angle, and the further development of the cracks weakens the strength of the rock, thereby increasing the probability of major engineering quality damage. The research results will have important reference value for hazard prevention in underground engineering projects through rock with natural and artificial defects, including tunnels and air-raid shelters.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제41권1호
• /
• pp.1-11
• /
• 2021

In order to reuse existing onshore turbine foundations, it is important to redesign and reinforce the existing foundations according to the upgraded tower diameter and turbine load. In the present study, a slab extension reinforcement method and structure details of an anchorage part were examined in consideration of the reuse of spread footings, which are the most widely used foundation type in onshore wind turbine foundations. Experiments were conducted to evaluate the load resistance performance of a reinforced spread footing according to structure details of an anchorage part. The results showed that (1) the strength of an anchorage part could be increased by more than 30 % by adding reinforcement bars in the anchorage part, (2) pile-sleeves attached to an anchor ring contributed to an increase in rotational stiffness by preventing shear slip behavior between the anchor ring and the concrete, and (3) slab connectors contributed to an increase in the strength and deformation capacity by preventing the separation of new and old concrete slabs.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제40권6호
• /
• pp.613-622
• /
• 2020

The South Korean government plans for a 37 % reduction in CO2 emissions against business as usual by 2030. Subsequently, the Ministry of Land, Infrastructure and Transport declared a 26.9 % reduction target in greenhouse gas emissions from buildings by 2020 and established the Green Standard for Energy and Environmental Design (G-SEED) to help improve the environmental performance of buildings. Construction companies often work with consulting firms to prepare for G-SEED certification. In the process, owing to inefficient data sharing and work connections, it is difficult to achieve economic efficiency and obtain certification. The objective of this study was to develop an economic model to assist contractors in achieving the required G-SEED scores for materials and resources. To do this, we automated the process for material comparison and selection on the basis of an analysis of actual consulting data, and developed a model that selects material alternatives that can meet the required scores at a minimum cost. Information on materials is input by applying a genetic algorithm to the optimization of alternatives. When the model was applied to actual data, the construction cost could be lowered by 79.3 % compared with existing methods. The economical material selection model is expected to not only reduce construction costs for owners desiring G-SEED certification but also shorten the project design time.

• Therapeutic Science for Rehabilitation
• /
• 제10권1호
• /
• pp.63-75
• /
• 2021

Objective : The purpose of this study was to examine the roles and practices of occupational therapists in public health centers based on their working experience of occupational therapists who are working in these facilities. Methods : We used Giorgi's descriptive phenomenological research method. Six occupational therapists were interviewed, and their recorded data were analyzed using Claizzi's thematic analysis. Results : As a result, 4 categories, 16 themes, and 24 elements were elicited. The major roles of occupational therapists in public health centers were the evaluation of clients, home-visit occupational therapy, management of dementia programs and community connection projects. Interventions that are needed to create a healthy community include case and program management, compensatory approaches, and healthy lifestyle interventions. The difficulties experienced by occupational therapists include their limited number job insecurity, performance-oriented administrative policy, and the lack of communication among professionals. Occupational therapists require education in health management and practice in public health centers to build their capacities. Conclusion : The results of this study could be used for guidelines for occupational therapists who work in community healthcare centers, as well as basic training for competent occupational therapists in the community.

• Journal of Korea Society of Industrial Information Systems
• /
• 제25권6호
• /
• pp.33-45
• /
• 2020

This paper aims to look at the perspective that the latest cutting-edge technologies are predicting individual diseases in the actual medical environment in a situation where various types of wearable devices are rapidly increasing and used in the healthcare domain. Through the process of collecting, processing, and transmitting data by merging clinical data, genetic data, and life log data through a user-participating wearable device, it presents the process of connecting the learning model and the feedback model in the environment of the Deep Neural Network. In the case of the actual field that has undergone clinical trial procedures of medical IT occurring in such a high-tech medical field, the effect of a specific gene caused by metabolic syndrome on the disease is measured, and clinical information and life log data are merged to process different heterogeneous data. That is, it proves the objective suitability and certainty of the deep neural network of heterogeneous data, and through this, the performance evaluation according to the noise in the actual deep learning environment is performed. In the case of the automatic encoder, we proved that the accuracy and predicted value varying per 1,000 EPOCH are linearly changed several times with the increasing value of the variable.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제22권3호
• /
• pp.352-361
• /
• 2021

An underwater positioning method that can be applied to structures for underwater construction is being developed at the Korea Institute of Ocean Science and Technology. The method uses an extended Kalman filter (EKF) based on an inertial navigation system for precise and continuous position estimation. The observation matrix was configured to be variable in order to apply asynchronous measured sensor data in the correction step of the EKF. A Doppler velocity logger (DVL) can acquire signals only when attached to the bottom of an underwater structure, and it is difficult to install and recover. Therefore, a complex sensor device for underwater structure attachment was developed without a DVL in consideration of an underwater construction environment, installation location, system operation convenience, etc.. Its performance was verified through a water tank test. The results are the measured underwater position using an ultra-short baseline, the estimated position using only a position vector, and the estimated position using position/velocity vectors. The results were compared and evaluated using the circular error probability (CEP). As a result, the CEP of the USBL alone was 0.02 m, the CEP of the position estimation with only the position vector corrected was 3.76 m, and the CEP of the position estimation with the position and velocity vectors corrected was 0.06 m. Through this research, it was confirmed that stable underwater positioning can be carried out using asynchronous sensors without a DVL.

• Journal of Digital Convergence
• /
• 제19권1호
• /
• pp.199-209
• /
• 2021

The purpose of this study was to analyze the factors that affect the satisfaction of smart seniors using smartphone delivery applications. We established the hypothesis by dividing the factors that will affect the satisfaction of smart seniors using smartphone delivery applications into the characteristics of the delivery app and the personal characteristics of the smart senior. In order to verify the hypothesis, we surveyed adult men and women aged 50 to 65 years old who had experience using delivery apps, and we performed confirmatory factor analysis, correlation analysis, and path analysis to perform statistical processing for data analysis. The analysis results are as follows. First, we found that usefulness among the characteristics of delivery app had a statistically significant positive effect on the delivery app satisfaction of smart seniors. Second, we found that social empathy among the personal characteristics of smart seniors had a statistically significant positive effect on the delivery app satisfaction of smart seniors. Third, we found that delivery app satisfaction had a statistically significant positive effect on reuse intention. Based on research result, we suggested that in order to improve the satisfaction and use of delivery app by smart seniors, it is necessary to develop delivery app that can be usefully used by smart seniors and focus on social empathy.

• Journal of Digital Convergence
• /
• 제19권1호
• /
• pp.475-483
• /
• 2021

The purpose of this study is to identify the temporal and spatial characteristics of pass accuracy by utilizing the second processing data and official records collected from the 2018 FIFA World Cup Russia video data. For a total of 128 games, the success rate of passes based on the results of the game, passing time, and passing position was two-way ANOVA with repeated measure. The results showed no difference between winning and losing groups, and no interaction effects were found for passing time and location. The difference in passing time was high in the first half, with the highest success rate in the middle of the first half (79.2%) and the middle of the second half (77.9%) in the 15~30 minutes and the 60~75 minutes. Pass success rates were in the order of defense-midfield area (83.9%), midfield-attack area (81.7%), defense area (70.6%) and attack area (61.1%). In conclusion, there was no difference in the passing success rate of the winning and losing teams depending on the characteristics of the relative competitive strength of the World Cup games, and it is believed that follow-up research is needed to analyze the game contents rather than the factors of the winning and losing in the future.

• The Journal of the Korea Contents Association
• /
• 제21권3호
• /
• pp.505-517
• /
• 2021

Lots of studies have been conducted on work-life balance in various fields. In particular, while a plethora of studies on the work-life balance have focused mainly on organizational culture and work performance, research to investigate the impact of work-life balance on employees' organizational commitment is scarce. This study aims to empirically analyze how work-life balance of employees affects organizational commitment and mediation effects of job satisfaction on the relationships through a survey of 463 employees working in small and medium-sized enterprises, public institutions, and conglomerates in the COVID-19 era. Also, it examines the impact of a smart work environment as a new way of working during the COVID-19 pandemic on job satisfaction and organizational commitment. The findings of the study are summarized as follows. First, work-life balance was shown to positively affect job satisfaction, and job satisfaction had a positive influence on emotional organizational commitment of employees. Second, job satisfaction was found to be completely mediated both in the relationship between work-life balance and organizational commitment and in the relationship between work-family balance and organizational commitment, and partially mediated in the relationship between work-growth balance and organizational commitment. Third, the smart work environment had a positive effect on job satisfaction and organizational commitment. The results of the study show that work and family, work and leisure, and work and growth balance are significantly important factors to improve employees' work attitudes in the changing work environment as a result of COVID-19. The present results suggest that the introduction of work-life balance and the smart work environment is required to increase organizational productivity.

• Journal of the Korean Recycled Construction Resources Institute
• /
• 제8권4호
• /
• pp.553-561
• /
• 2020

Water-soluble rubber asphalt-based waterproofing material, which is one of the waterproofing materials for building structures, is mainly used indoors (toilet, kitchen, balcony, etc.). In general, asphalt-based materials are used for non-exposed installation, rather than as exposed type as they do not deviate from their usual basic black pigmentation, and water-soluble rubber asphalt-based coating waterproofing materials are basically limited to indoors because of their low physical properties. Accordingly, in order to improve the tensile and elongation properties, a silane coupling agent, an inorganic filler, and a processor oil w ere added to improve the physical properties, and accordingly, the basic physical properties of the outdoor coating waterproofing material quality standard were analyzed. As a result, the water-soluble rubber asphalt coating waterproofing material compared with the exposure quality standard showed a result that exceeded the basic physical property quality standard of silicone rubber in all items under test evaluation, but the tensile strength and tear strength of the first class of urethane rubber were chloroprene. It was found that the performance compared to the quality standards of rubber-based tear strength was about 34.2% to about 40.8%.