• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.83-91
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• 2006

Recently, the intensive rainstorm possibly induced by global warming plays a key role on the instability of railway adjacent slopes. The instability of slopes results as covering and loss of railway lines induced by slided soil mass. According to the site investigation on the failed slopes triggered by rainfall, low types of slope failure were observed: shallow, intermediate, gully erosion, and soil-rock interface failures. The observation reveals the different characteristics of slope failure depending on the thickness of soil layer, morphological features of slope, etc. Based upon the observations, flume tests were conducted to analyze the sliding mechanism of each failure. The variables of flume test are soil layer thickness, rainfall intensity, and morphology of slope under the constant condition of the percentage of fine, initial soil moisture content, slope angle and compaction energy. Test results show that shallow failure was mostly observed from the surface of the slope and caused by the soil erosion; in addition, compared to the other types of failure, the occurrence of initial erosion is late, however, the development of erosion is fast. In gully erosion failure, the collected water from the water catchment area helps erosion of the upper soil layer and transfer of residual corestone, which impedes the erosion process once the upper soil layers are eroded and corestone are exposed. The soil-rock interface failure shows the most fast initial erosion process among the failure types. Interestingly, the common feature observed from the different types of failure was the occurrence of the initial deformation near the toe of slopes which implies the existence of surbsurface flow along the downslope direction.

• Korea Science and Art Forum
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• v.25
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• pp.449-461
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• 2016

This study was to investigate convention service quality that affect convention destination visiting values and intention to behavior from foreign convention attendances' perspectives. From the literature review, convention service quality and destination visiting value were discussed to provide logical linkage among proposed concepts. A total of 308 useful date were collected from on site survey at the convention centers in Seoul. Factor analysis and multiple regression analysis were performed to achieve the objective of this study. Factor analysis showed that there were four underlying dimensions in the convention service quality such as mutual human interaction, program quality, useful information, transportation and convenient facility. Multiple regression showed that these convention service quality affects destination visiting values and behavior intention. More discussion and implication are provided in the conclusion section.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.117-124
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• 2016

Researches on soil microbial community are increasing to assess ecosystem responses to anthropogenic disturbances and to provide an indicator of ecosystem recovery. Microbial communities are able to respond more rapidly to environmental changes than plants and therefore they may provide an early indication of the ecosystem recovery trajectory. This study was conducted using 16S rRNA gene pyrosequencing of soil samples to compare soil bacterial community composition between artificially covered soils of the Baedudaegan ridgeline and their adjacent forest soils in two restoration project sites, Ihwaryeong and Yuksimnyeong, which were completed in 2012 and 2013, respectively. Richness of the Phylum level was 29.3 in Ihwaryeong and 32.3 in Yuksimnyeong. Significant difference in the richness between artificial restored soils and adjacent forest soils(p<0.01) was observed, however no significant difference was observed for site location and soil depth. Acidobacteria(37.3%) and Proteobacteria(31.1%) were more abundant than any other phylum in collected soil samples. Also, we found the significant difference in the relative abundance of the two abundant phyla between artificially restored soils and their adjacent forest soils (Proteobacteria, 38.1% in restored soils vs 24.2% in adjacent forest soils, p<0.01; Acidobacteria, 55.4% in restored soils vs 19.2% in adjacent forest soils, p<0.001). The results support the previous researches indicating that soil bacterial community composition is affected by nutritional status of soils and that Acidobacteria is also strongly influenced by pH, thus favoring soils with lower pH. This study could be utilized to monitor and evaluate restoration success of forest soil environment quantitatively.

• Korean Journal of Construction Engineering and Management
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• v.24 no.4
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• pp.3-13
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• 2023

The purpose of this study is to compare and analyze the performance and work productivity of wet type pavement cutters and sludge suction type pavement cutters (hereinafter referred to as automatic pavement cutters) developed to reduce scattering dust. We first investigated the development status of wet type manual pavement cutters that are mainly used in Korea and automatic pavement cutters, and analyzed the pavement cutting work in detail. And the standard cutting performance was derived by measuring the cutting time by depth by applying the two equipment to the test bed under the same conditions. However, there is a limitation that the data measured in the test bed does not reflect the various variables of the actual pavement cutting site. Therefore, in this study, data was collected through field surveys, and the correlation between cutting distance and time was analyzed, and then a model for calculating the productivity of pavement cutters was presented through simple regression analysis. As a result of comparative analysis of the values derived from the regression equation with the standard cutting performance derived from the test bed, the cutting performance derived through the regression equation showed a similar trend to the standard cutting performance. Finally, we verified the usability of the automated pavement cutter developed by qualitatively analyzing three tasks that are difficult to measure quantitatively but affect productivity.

• The Mathematical Education
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• v.61 no.2
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• pp.257-271
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• 2022

As information and communication technologies are being developed so rapidly, education research is actively conducted to provide optimal learning for each student using big data and artificial intelligence technology. In this study, using the mathematics learning data of elementary school 5th to 6th graders conducting blended mathematics classes, we tried to find out what factors predict mathematics academic achievement and developed an artificial intelligence model that predicts mathematics academic performance using the results. Math learning propensity, LMS data, and evaluation results of 205 elementary school students had analyzed with a random forest model. Confidence, anxiety, interest, self-management, and confidence in math learning strategy were included as mathematics learning disposition. The progress rate, number of learning times, and learning time of the e-learning site were collected as LMS data. For evaluation data, results of diagnostic test and unit test were used. As a result of the analysis it was found that the mathematics learning strategy was the most important factor in predicting low-achieving students among mathematics learning propensities. The LMS training data had a negligible effect on the prediction. This study suggests that an AI model can predict low-achieving students with learning data generated in a blended math class. In addition, it is expected that the results of the analysis will provide specific information for teachers to evaluate and give feedback to students.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.513-521
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• 2008

The objective of this study is the evaluation of the impact on the construction condition due to historical observation data and IPCC SRES A2 climate change scenario. For this purpose, daily precipitation and daily mean temperature data which have been observed over the past 30 years by Korea Meteorological Administration are collected and applied. Also, A2 scenarios during 2011~2040 and 2051~2080 are used for this analysis. According to the results of trend analyses on annual precipitation and annual mean temperature, they are on the increase mostly. The available working day and the day occurred an extreme event are used as correlation indices between climate factor and construction condition. For the past observation data, linear regression and Mann-Kendall test are used to analyze the trend on the correlation index. As a result, both working day and extreme event occurrence day are increased. Likewise, for the future, variation analysis showed the similar result to that of the past and the occurrence frequency of extreme events is increased obviously. Therefore, we can project to increase flood damage potential on the construction site by climate change.

• Smart Media Journal
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• v.11 no.7
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• pp.9-18
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• 2022

With the outbreak of COVID-19, the world is in unexpected chaos. In particular, the Korean economy, which has a large number of self-employed people, is experiencing enormous damage from COVID-19. The purpose of this study is to analyze the causal impact of start-ups and closures by industry due to the COVID-19 outbreak. For the causal impact analysis, we collected and analyzed 8,312,224 cases of start-up and closure of 190 businesses that occurred on the local administrative license data public site for 11 years from 2010 to 2020. As a result of the analysis of the causal impact of COVID-19, there were 29 industries in which start-ups increased(increase rate 313.14% ~ 6.39%), 23 industries in which start-ups decreased(decrease rate 70.62% ~ 11.27%), 21 industries in which closures increased(increase rate 157.55% ~ 13.57%), and 18 industries in which business closures decreased(reduction rate 49.45% ~ 12.91%). The industries in which start-ups increased and closures decreased due to the COVID-19 outbreak were disinfection, food transportation, and general sales of health functional food. The industries in where start-ups decreased and closures increased due to the COVID-19 outbreak were youth game providing industry, danran pub business, and general game providing industry. It is expected that the results of this study will help practitioners who manage various infectious diseases to understand the causal impact of infectious disease outbreaks and to prepare countermeasures.

• 한국노년학
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• v.29 no.2
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• pp.669-682
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• 2009

The purpose of this study was to explore the role of professional identity as mediating variable in the relationship between job- and organization- related factors and job satisfaction. This study surveyed social workers who worked at 24 senior welfare facilities in Daegu·Gyeoungbuk province from Aug. 1. to Aug. 30. 2006. A total of 137 questionnaires were collected using on-site survey (response rate 76.7%). Statistical analyses were performed using SPSS 12.0 for Windows. Descriptive analysis and frequency analysis were performed on overall measurement items and hierarchical regression analysis was conducted to test the mediating effect of professional identity. The reliability of statements was acceptable since the coefficient alphas were > .70. Results of hierarchical regression showed that professional identity was verified as a partial mediator in the relationship between factors related with job and organization and job satisfaction. As the population ages, there will be an increasing need for professional social workers effectively to work with and help care for the elderly. This study highlighted that job- and organization- related factors, namely self-regulations and social supports, are significantly related with job satisfaction of social workers. Especially, such effect was more significantly apparent in high professional identity which is playing a partial mediator. This result implies that there is potential to change work environments of social workers ensuring a delegation of power and responsibility. Therefore, efforts should be made to improve the promotion system and connect social worker as servant with community through diverse service learning programs.

• Journal of Trauma and Injury
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• v.36 no.3
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• pp.187-195
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• 2023

Purpose: This study aimed to determine the risk factors associated with the severity of fall-related injuries among patients who suffered a fall from similar heights and analyze differences in injury sites according to intentionality and injury severity. Methods: The Emergency Department-based Injury In-depth Surveillance (EDIIS) data collected between 2019 and 2020 were used in this retrospective study. Patients with fall-related injuries who fell from a height of ≥6 and <9 m were included. Patients were categorized into the severe and mild/moderate groups according to their excessive mortality ratio-adjusted Injury Severity Score (EMRISS) and the intention and non-intention groups. Injury-related and outcome-related factors were compared between the groups. Results: In total, 33,046 patients sustained fall-related injuries. Among them, 543 were enrolled for analysis. A total of 256 and 287 patients were included in the severe and mild/moderate groups, respectively, and 93 and 450 patients were included in the intention and non-intention groups, respectively. The median age was 50 years (range, 39-60 years) and 45 years (range, 27-56 years) in the severe and mild/moderate groups, respectively (P<0.001). In multivariable analysis, higher height (odds ratio [OR] 1.638; 95% confidence interval [Cl], 1.279-2.098) and accompanying foot injury (OR, 0.466; 95% CI, 0.263-0.828) were independently associated with injury severity (EMR-ISS ≥25) and intentionality of fall (OR, 0.722; 95% CI, 0.418-1.248) was not associated with injury severity. The incidence of forearm injuries was four (4.3%) and 58 cases (12.9%, P=0.018) and that of foot injuries was 20 (21.5%) and 54 cases (12.0%, P=0.015) in the intention versus non-intention groups, respectively. Conclusions: Among patients who fell from a similar height, age, and fall height were associated with severe fall-related injuries. Intentionality was not related to injury severity, and patients with foot injury were less likely to experience serious injuries. Injuries in the lower and upper extremities were more common in intentional and unintentional falls, respectively.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.849-858
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• 2023

Investigating disaster sites such as earthquakes and landslides involves significant risks due to potential secondary disasters like facility collapse. In situations where direct access is challenging, there is a need to develop methods for safely acquiring high-precision 3D disaster information using light detection and ranging (LiDAR) equipped drone survey systems. In this study, the feasibility of using drone LiDAR in disaster scenarios was examined, focusing on the collapse accident at Jeongja Bridge in Bundang-gu, Seongnam City, in April 2023. High-density point clouds for the accident bridge were collected, and the bridge's 3D terrain information was reconstructed and compared to the measurement performance of 10 ground control points. The results showed horizontal and vertical root mean square error values of 0.032 m and 0.055 m, respectively. Additionally, when compared to a point cloud generated using ground LiDAR for the same target area, a vertical difference of approximately 0.08 m was observed, but overall shapes showed minimal discrepancies. Moreover, in terms of overall data acquisition and processing time, drone LiDAR was found to be more efficient than ground LiDAR. Therefore, the use of drone LiDAR in disaster sites with significant risks allows for safe and rapid onsite investigations.