• Smart Structures and Systems
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• v.22 no.6
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• pp.675-687
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• 2018

In the previous studies on the porous rock strength the effect of pore number and its diameter is not explicitly defined. In this paper crack initiation, propagation and coalescence in Brazilian model disc containing a single cylindrical hole and or multiple holes have been studied numerically using PFC3D. In model with internal hole, the ratio of hole diameter to model diameter was varied between 0.03, 0.17, 0.25, 0.33, and 0.42. In model with multiple hole number of holes was different in various model, i.e., one hole, two holes, three holes, four holes, five holes, six holes, seven holes, eight holes and nine holes. Diameter of these holes was 5 mm, 10 mm and 12 mm. The pre-holed Brazilian discs are numerically tested under Brazilian test. The breakage load in the ring type disc specimens containing an internal hole with varying diameters is measured. The mechanism of cracks propagation in the wall of the ring type specimens is also studied. In the case of multi-hole Brazilian disc, the cracks propagation and b cracks coalescence are also investigated. The results shows that breaking of the pre-holed disc specimens is due to the propagation of radially induced tensile cracks initiated from the surface of the central hole and propagating toward the direction of diametrical loading. In the case of disc specimens with multiple holes, the cracks propagation and cracks coalescence may occur simultaneously in the breaking process of model under diametrical compressive loading. Finally the results shows that the failure stress and crack initiation stress decreases by increasing the hole diameter. Also, the failure stress decreases by increasing the number of hole which mobilized in failure. The results of these simulations were comprised with other experimental and numerical test results. It has been shown that the numerical and experimental results are in good agreement with each other.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.14-24
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• 2019

It is necessary to look into multiple subjects, such as effectiveness, laws and polices of blockchain in order to easily accept blockchain technology in small and mid-sized enterprises(SME). This study analyzes the positive effects of applying the block chain to SMEs, examines the laws and policies required to apply them, and identifies the tasks. As a result, we confirmed that it can create positive effects such as optimizing supply chain management, simplifying import and export process documents, improving product quality, facilitating flow of funds, and improving transaction reliability. Also, we confirmed that it is necessary to improve the basic law of electronic transaction, electronic commerce law, electronic financial transaction law, personal information protection legislation, and needs policy supplement for platform development, education system for SMEs, transaction standardization guidelines, tax reduction policy, and block chain research and development. More extensive practical research and specific individual legal studies are needed in the future.

• International journal of advanced smart convergence
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• v.8 no.3
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• pp.123-130
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• 2019

In the study, we suggest that the activation plan of the public nature burial in the capital area through funeral information system as follows. First, according to the report on the social survey announced by the National Statistical Office in December 2017, the Korean people's preference of nature burial was 43.6% while the actual utilization rate of national nature burial in 2017 was only 8.8%, which showed a huge gap between preference and utilization rate of nature burial. Therefore, through the activities to improve the awareness of nature burial by performing the national promotion and education, and also the investment for the expansion or improvement of nature burial facilities in the level of central government and local government, the preference of nature burial should be led to the actual demand. Second, during the period from 2011 to 2018, the utilization rate of public nature burial in the capital area was annually increased by average 26.9%, which showed the huge increase of demand for nature burial. Thus, each local government should carry forward the policies for expanding the supply of public nature burial focusing on the woodland burial showing the high preference of users of public nature burial. Third, even though the public cremation facilities are installed or operated by local governments in the capital area, Seongnam City without the public cremation facilities should install the public nature burial for the enhancement of users convenience by providing the One Stop Total Funeral Service.

• Journal of Child Welfare and Development
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• v.16 no.2
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• pp.47-66
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• 2018

This study aimed to identify any possible correlations among the empathy ability, peer relationships, and smartphone addiction of upper-grade elementary school students; the effects of empathy ability and peer relationships on smartphone addiction; and to verify the mediating effect of the empathy ability between peer relationships and smartphone addiction. To this end, the empathy ability, peer relationship, and smartphone addiction tests were conducted among 154 six-grade elementary school students in Gyeonggi and Our findings were as follows; First, in terms of the correlations among empathy ability, peer relationships, and smartphone addiction, the empathy ability and peer relationships were shown to have a positive correlation while the empathy ability and smartphone addiction turned out to have a negative correlation, which was also the case between peer relationships and smartphone addiction. Second, when it came to the effects of the empathy ability and peer relationships on smartphone addiction, the emotional empathy as part of the empathy ability and the esteem out of peer relationships were shown to have a negative effect on smartphone addiction, indicating that an increase of emotional empathy and esteem resulted in less smart phone addiction. Third, in terms of the effect of peer relationships on smartphone addiction with the empathy ability as a medium, peer relationships and smartphone addiction were shown to be partially mediated by the empathy ability. These findings are meaningful in that they could serve as the basic data for the development of smartphone addiction prevention programs for elementary school students.

• Industry Promotion Research
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• v.6 no.2
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• pp.47-53
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• 2021

This study is a study on the change of life and leisure satisfaction caused by the reduction of working hours of office workers, summarizing the results of the analysis as follows: First, the change in the working hours of office workers was found to be men (42.4 percent), but women (54.7 percent) had a high increase in personal satisfaction, monthly income of 2 to 3 million won 96.1 percent, and personal satisfaction increased in small and medium-sized cities and towns. Second, leisure satisfaction due to shorter working hours was somewhat high in monthly income of 3 million won to 4 million won (43.6%) and more than 6 million won (39.1%), but there was no change in leisure satisfaction by gender, age, academic background, number of family members, marital status, worker status and region. The revitalization of leisure is a very important task in personal life, but it is meaningful in that it provided implications for socializing leisure as leisure satisfaction is positively spreading in life changes.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.25-31
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• 2021

Moving toward an aged society, traffic accidents involving elderly drivers have also attracted broader public attention. A rapid increase of senior involvement in crashes calls for developing appropriate crash-severity prediction models specific to senior drivers. In that regard, this study leverages machine learning (ML) algorithms so as to predict the severity of vehicle-pedestrian collisions induced by elderly drivers. Specifically, four ML algorithms (i.e., Logistic model, K-nearest Neighbor (KNN), Random Forest (RF), and Support Vector Machine (SVM)) have been developed and compared. Our results show that Logistic model and SVM have outperformed their rivals in terms of the overall prediction accuracy, while precision measure exhibits in favor of RF. We also clarify that driver education and technology development would be effective countermeasures against severity risks of senior driver-induced collisions. These allow us to support informed decision making for policymakers to enhance public safety.

• Journal of Convergence for Information Technology
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• v.9 no.10
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• pp.213-219
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• 2019

This study is a descriptive research on the relationship among smartphone addiction, lack of sleep and sleeping hours of undergraduates. The subjects include 280 students enrolled in G university and data were collected from Sep. 6 to Oct. 10, 2018. On average, each score of smartphone addiction, sleeping hours and lack of sleep was $34.79{\pm}7.6$, $6.43{\pm}1.34$ and $10.14{\pm}3.14$ respectively. Smartphone addition had a significantly positive correlation with lack of sleep(r=.277, p<0.01) and a positive correlation with its sub-areas, such as disability in daily life(r=.269, p<0.01), virtual(r=.151, p<0.01), withdrawal(r=.303, p<0.01), tolerance(r=.184, p<0.01). The education and counselling for preventing undergraduates from smartphone addiction and further studies on them are required.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.47-58
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• 2021

Recently, personal mobility (PM)-related complaints and PM accidents have increased as the number of users soars due to growth in the domestic PM market and the emergence of a number of electric scooter-sharing services. As a result, the need for PM education and practice spaces is emerging as a way to reduce accidents caused by poor PM manipulation and operation. In this study, we analyze the relevant conflict factors in order to come up with a systematic operation and activation plan for PM, and as an alternative, we review and propose how to operate a PM playground and test zone. It is expected that basic data collection and analysis of rudimentary driver behavior through PM playground operations will improve users' operational safety, and various conflicts of interest between users and non-users will be resolved by installing facilities to secure their safety.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.307-313
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• 2021

Most of the stores of small business owners are those that use a large number of electrical devices, and in particular, there are many stores that use a cold storage system. In severe cases, there is a lot of power load on the store, which can cause a loss to the assets in the store as the power supply is cut off. Accordingly, in this paper, an LSTM-based power load prediction system was designed to measure the energy demand rate of stores and to save energy. Since it can be used as a data-based power saving system for small and medium-sized stores, it is expected to be used as a data-based power demand prediction system for small businesses in the future, and to be used in the field of preventing damage due to power load.

• Journal of the Korea Society of Computer and Information
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• v.27 no.4
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• pp.61-77
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• 2022

The purpose of this study is to explain intention to use untact medical diagnosis and consultation services. We carried out the analysis of the survey data using Smart PLS 3.0 to test the hypotheses how the expected benefit variables and perceived risk variables of untact medical diagnosis and consultation services affect intention to use. According to the empirical analysis results, this study confirmed that quality of telemedicine service had a significant effects on perceived usefulness, Perceived Easy of Use. And accessibility had a significant effects on perceived easy of use, cost saving and expected benefits had a significant effects on use Intention of untact medical diagnosis and consultation services. Performance risk and service risk had a significant effect on medical risk. And medical risk had a significant negative(-) effects on use Intention of untact medical diagnosis and consultation services. This study has its meaning because it found out that it deals structurally and expansively with use intention of untact medical diagnosis and consultation services through positive and negative factors.