• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.15-23
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• 2005

For reliability assessment for machine tools, failure mode analyses by two viewpoints were studied in this paper. First, this study developed the reliability data analysis program, which searches f3r optimal failure distribution like failure rate or MTBF(Mean Time Between Failure) using failure data and reliability test data of mechanical parts in the web. Moreover, this data analysis program saves both failure data or reliability data and their failure rate or MTBF for database establishment. Second, this paper conducted failure mode analysis through such performance tests as circular movement test and vibration testing for machine tools when reliability data is not available. A developed web-based analysis program shows correlations between failure mode and performance test result and also accumulates all the data. These kinds of data analysis programs and stored data furnish valuable information for improving the reliability of mechanical system.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.201-207
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• 2007

Researchers have used a variety of methods to measure patterns of animal movement, including the use of spatial data (mapping the position of a moving animal at specified intervals) and direct estimation of travel path length by pacing under a moving animal or group. I collected movement data from five groups of siamangs (Symphalangus syndactylus) using two different methods concurrently to estimate the effects of the method of data collection on estimates of daily path length (DPL). Estimates of DPL produced from spatial data collected at 15-minute intervals were 12% lower than estimates of DPL produced by pacing under the traveling animal. The actual magnitude of the difference was correlated with the travel distance, but there was no correlation between the proportional difference and the travel distance. While the collection of spatial data is generally preferable, as spatial data permit additional analyses of patterns of movements in two or three dimensions, the relatively small difference between the DPL's produced using different methods suggests that pacing is an acceptable substitute where the collection of spatial data is impractical. I also subsampled the spatial data at increasing time intervals to assess the effect of sampling interval on the calculation of daily path lengths. Longer sampling intervals produced significantly shorter estimates of travel paths than shorter sampling intervals. These results suggest that spatial data should be collected at short time intervals wherever possible, and that sampling intervals should not exceed 30 minutes. Researchers should be cautious when comparing data generated using different methods.

• The Korean Journal of Community Living Science
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• v.27 no.spc
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• pp.651-663
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• 2016

This study explores the background and the processes underpinning the educational reform movement based on local community. This educational community initiated the alternative education reform movement, which is referred to as the small school movement. A qualitative case study was implemented by collecting data from thirty articles, three focused interviews. This study drew out three key factors as the operation of educational community in regional area. First, it claimed a total of 30 papers related to the educational community for content analysis. Second, key words were derived in the local educational community context. They developed their own alternative educational programs, such as self-supportive meeting, season carnivals, community revitalization activities, and so on. Their focus was on finding out and establishing better educational relationships among the concerned communities. Third, the community continues to reinforce the internal rules and climate through meta-education, a process, in which education educates itself. As a result, they could enjoy substantial success in a visible educational community. This small school revival movement later grew into the new school movement. Furthermore, a variety of teachers, parents groups, and interested scholars have been engaged in the community movement through professional networking. This study suggests that the key innovator-initiated movement, which involves education reform, upgraded Korean education, and improved their own expertise and autonomy, is expected to be the first step to solve the current Korean educational problems by the educational community.

• Archives of Plastic Surgery
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• v.39 no.3
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• pp.204-208
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• 2012

Background : Isolated pure blowout fractures are clinically important because they are the main cause of serious complications such as diplopia and limitation of extraocular movement. Many reports have described the incidence of blowout fractures associated with diplopia and limitation of extraocular movement; however, no studies have statistically analyzed this relationship. The purpose of this study was to demonstrate the correlation between the location of isolated pure blowout fractures and orbital symptoms such as diplopia and limitation of extraocular movement. Methods : We enrolled a total of 354 patients who had been diagnosed with isolated pure blowout fractures, based on computed tomography, from June 2008 to November 2011. Medical records were reviewed, and the prevalence of extraocular movement limitations and diplopia were determined. Results : There were 14 patients with extraocular movement limitation and 58 patients complained of diplopia. Extraocular movement limitation was associated with the following findings, in decreasing order of frequency: floor fracture (7.1%), extended fracture (3.6%), and medial wall (1.7%). However, there was no significant difference among the types of fractures (P=0.60). Diplopia was more commonly associated with floor fractures (21.4%) and extended type fractures (23.6%) than medial wall fractures (10.4%). The difference was statistically significant (Bonferroni-corrected chi-squared test P<0.016). Conclusions : Data indicate that extended type fractures and orbital floor fractures tend to cause diplopia more commonly than medial wall fractures. However, extraocular movement limitation was not found to be dependent on the location of the orbital wall fracture.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.349-359
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• 2019

This study investigated the current state of Korean Maker Movement and explored the ways for activating Maker Movement in Korea. To do this purpose, we analyzed the data of 'A survey of the Korea Maker Movement in the second half of 2018', conducted by Korea Foundation for the Advancement of Science & Creativity involved 20's~50's Koreans. As a results, first, awareness, interest and behavior intention of Maker Movement was not high in Korea. Second, there were significant different between participants and non-participants of Maker Community in Maker awareness and Maker activities. Third, the positive relation between Maker Community participation and Maker Orientation is parallel multiple mediated by Maker activating motives such as fun, relieving stress, expressing own idea, saving cost, social recognition. Lastly, based upon the results, we presented several ways to activate Maker Movement in Korea.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.623-632
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• 2018

Both investors and researchers are attentive to the prediction of stock price movement directions since the accurate prediction plays an important role in strategic decision making on stock trading. According to previous studies, taken together, one can see that different factors are considered depending on stock markets and prediction periods. This paper aims to analyze what data mining techniques show better performance with some representative index and stock price datasets in the Korea stock market. In particular, extreme gradient boosting technique, proving itself to be the fore-runner through recent open competitions, is applied to the prediction problem. Its performance has been analyzed in comparison with other data mining techniques reported good in the prediction of stock price movement directions such as random forests, support vector machines, and artificial neural networks. Through experiments with the index/price datasets of 12 years, it is identified that the gradient boosting technique is the best in predicting the movement directions after 1 to 4 days with a few partial equivalence to the other techniques.

• Journal of the Korea Convergence Society
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• v.11 no.7
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• pp.169-180
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• 2020

The purpose of this study was to find the characteristics of the foreign and domestic travels and to seek out the significance of the study, by grouping the geotweets users who moved abroad, according to the average and the standard deviation of moving distances. Geotweets which caused foreign and domestic travels occurred divided, after building a data mart and the moving distances of users were measured by using the Haversine formula. It has moved more often among groups of foreign travelers in countries that use the same language and have similar lifestyles. There has been a lot of movement in developed countries with well-established infrastructure in a group of domestic travelers. This study tried to draw common features, by calculating the travel distances by each user and grouped users according to the characteristics of user's moving distances. There are significant differences in national economic power, age, jobs, etc. among users from a total of 21 countries analyzed by this study, so a more precise analysis would be able to be conducted, only if the whole conditions are considered. A future study should additionally consider real factors.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.201-210
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• 2014

Recently, the more complicated with the elements made of information system, the more dangerous in migration them. So it is need to accomplish information system migration systematically. According to the movement of public institution, a large scale of information system migration is in processing and will be made. In this paper, I would like to suggest the use of migration solution in order to speed & effect information system migration process. This will be provided the pursuit function of information system movement, movement location pursuit in real time, monitoring function through the situation room, separation migration possibility on the basis of business attribute. Therefore, if you use the suggested solution, it will be decreased trial and error & minimized the movement time.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.287-295
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• 2022

The GNSS coordinate time series is used as important data for geophysical analysis such as terrestrial reference frame establishment, crustal deformation, Earth orientation parameter estimation, etc. However, various factors may cause discontinuity in the coordinate time series, which may lead to errors in the interpretation. In this paper, we describe the discontinuity in the coordinate time series due to the equipment replacement for domestic GNSS stations and discuss the change in movement magnitude and velocity vector difference in each direction before and after discontinuity correction. To do this, we used three years (2017-2019) of data from 40 GNSS stations. The average magnitude of the velocity vector in the north-south, east-west, and vertical directions before correction is -12.9±1.5, 28.0±1.9, and 4.2±7.6 mm/yr, respectively. After correction, the average moving speed in each direction was -13.0±1.0, 28.2±0.8, and 0.7±2.1 mm/yr, respectively. The average magnitudes of the horizontal GNSS velocity vectors before and after discontinuous correction was similar, but the deviation in movement size of stations decreased after correction. After equipment replacement, the change in the vertical movement occurred more than the horizontal movement variation. Moreover, the change in the magnitude of movement in each direction may also cause a change in the velocity vector, which may lead to errors in geophysical analysis.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.