• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.69-76
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• 2017

Bluetooth Low Energy (BLE), also known as Bluetooth Smart, has ultra-low power consumption; in fact, BLE-enabled devices can run on a single coin cell battery for several years. In addition, BLE can estimate the approximate distance between two devices using the Received Signal Strength Indication (RSSI) feature, enabling relatively precise navigation in indoor and small outdoor areas where GPS is not an option. In this paper, an experimental setup is presented in which BLE is used for navigation within a small outdoor area. BLE-based beacons are installed in fixed positions, which periodically transmit a universally unique identifier (UUID). A smart device receives the UUID and sends it to a database server using cellular or Wi-Fi technology. The server returns fixed position information corresponding to the received UUID codes, and the smart device uses that information to compute its current position based on relative signal strengths, and display it on a map. These results demonstrate the successful application of BLE technology for navigation in small outdoor areas. This system can be implemented for indoor navigation as well.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.169-173
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• 2015

This study is to predict the life exponent by measuring, over 7 years, the insulation resistance of high-voltage cables in 22 kV operation for 13 years. We found out the lifetime index in order to determine the time-dependent trend of deteriorating performance of power cables. The insulation resistances decreased according to elapsed time. We found that: the initial measurements of the cable systems were in agreement with the deterioration properties of the Arrhenius Law. By analyzing the life curve of the cable system, we also verified that the value of the life exponent (n) in the v-t characteristics defined by Weibull distribution has values from 10 to 11. When designing the cable system, the initial value of life exponent was chosen as 9 without any grounding. We have verified that the theoretical grounding based on the design safety of n=9 was actually the best one available. In the short term, we apply our research result to the diagnosis and evaluation of the power cables. In the long run, however, we plan to reduce the cost of the installation and management of cable systems in operation at power stations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.393-401
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• 2024

Recently, the Internet of Things (IoT) has been widely used in industries and daily life that directly affect human safety, life, and assets. However, IoT devices, which need to meet low-cost, lightweight, and low-power requirements, face a significant problem of shortened battery lifetime due to battery draining attacks and interference. To solve this problem, the 802.11ba standard for the Wake-up Receiver (WuR) has emerged, this feature is playing a crucial role in minimizing energy consumption. However, the WuR protocol did not consider security mechanisms in order to reduce latency and overhead. Therefore, in this study, anAdaptive Power Saving Mechanism (APSM) is proposed for low-power WuR to counter battery draining attacks. APSM can minimize abnormally occurring power consumption by exponentially increasing power-saving time in environments prone to attacks. According to experimental results, the proposed APSM improved energy consumption efficiency by a minimum of 13.77% compared to the traditional Legacy Power Saving Mechanism (LPSM) when attack traffic ratio is 10% or more of the total traffic.

• Journal of Internet Computing and Services
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• v.17 no.5
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• pp.151-160
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• 2016

The purpose of this research is to investigate Korean popular attitudes and social perceptions of 'sharing economy' terminology at the current moment from a creative or socio-economic point of view. In Korea, this study discovers and interprets the objective and tangible annual changes and patterns of sociocultural collective intelligence that have taken place over the last five years by applying text mining in the big data analysis approach. By crawling and Googling, this study collected a significant amount of time series web meta-data with regard to the theme of the sharing economy on the world wide web from 2010 to 2014. Consequently, huge amounts of raw data concerning sharing economy are processed into the value-added meaningful 'word clouding' form of graphs or figures by using the function of word clouding with R programming. Till now, the lack of accumulated data or collective intelligence about sharing economy notwithstanding, it is worth nothing that this study carried out preliminary research on conducting a time-series big data analysis from the perspective of knowledge management and processing. Thus, the results of this study can be utilized as fundamental data to help understand the academic and industrial aspects of future sharing economy-related markets or consumer behavior.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.305-322
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• 2016

With the multiplex and wide release strategy, the monopolies of four major distribution companies and three multiplex chain, the polarization of Korean movie's Box Office performance is deepening. The four major distributor of NEW, CJ CGV, Lotte Cinema distributed 290 movies of 538 movies produced from 2009 to 2014 in Korea. The audience market share of these four distributors is 85.74%, while other 248 movies covers only 14.26%, which are distributed by outsides of the four major distribution system. The concentration of film admission has been deepened in Gini Index from 0.53 in 2004 to 0.85 in 2014. The movies distributed by others rather than four major companies suffers inequality in numbers of secured screens, screening times, and secured seats of movie theaters. In the highest 10% of box-office ranking, there is only one movie distributed by others. The lowest 50% of box-office ranking, there are 186 movies by others, while four companies have 81 movies. However, Occupancy rate of seat of major companies is lower than 16.83% of that of the others in the lowest 50% section. Workers of Korean movie industry are suffered from this polarization and they seek their breakthrough by producing erotic movies for VOD in recent years.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.699-704
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• 2018

One-dimensional nanostructures have attracted increasing attention because of their unique electronic, optical, optoelectrical, and electrochemical properties on account of their large surface-to-volume ratio and quantum confinement effect. Vertically grown nanowires have a large surface-to-volume ratio. The vapor-liquid-solid (VLS) process has attracted considerable attention for its self-alignment capability during the growth of nanostructures. In this study, vertically aligned silicon oxide nano-pillars were grown on Si\$SiO_2$(300 nm)\Pt substrates using two-zone thermal chemical vapor deposition system via the VLS process. The morphology and crystallographic properties of the grown silicon oxide nano-pillars were investigated by field emission scanning electron microscopy and transmission electron microscopy. The diameter and length of the grown silicon oxide nano-pillars were found to be dependent on the catalyst films. The body of the silicon oxide nano-pillars exhibited an amorphous phase, which is consisted with Si and O. The head of the silicon oxide nano-pillars was a crystalline phase, which is consisted with Si, O, Pt, and Ti. The vertical alignment of the silicon oxide nano-pillars was attributed to the preferred crystalline orientation of the catalyst Pt/Ti alloy. The vertically aligned silicon oxide nano-pillars are expected to be applied as a functional nano-material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.49-55
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• 2019

An open office or a shared office is emerging as the emphasis on the collaborative and communicative work environments is increasing. In the past, the user maintained the space, but the maintenance of indoor space became difficult because there is no fixed user. Indoor space information can be collected using the ICBM framework system. The facility management can achieve this with data. Therefore, this study proposed a framework based on ICBM (Internet of Things, Cloud, Big Data, and Mobile) for verifying the possibility of a smart facility management system for indoor space. IoT (Internet of Things) technology was used to measure the indoor temperature, humidity, occupancy, and brightness continuously, and provided the data to Web API via WiFi. Data acquired automatically via IoT, existing maintenance data, and spatial information were integrated through the Cloud. Big data collected by sensors were processed as meaningful spatial information for maintenance. Indoor space information and maintenance information can be delivered to the manager through the mobile. Based on the collected data, room occupancy recognition is limited due to a range of ultrasonic wave sensors. On the other hand, brightness represents the space conditions. The difference between lighting on/off, weekday and weekend can be shown. The temperature data and the relative humidity data were collected steadily to evaluate the comfort.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.643-650
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• 2021

The purpose of this study was to evaluate the impact of lecture content on the overall academic satisfaction in non-contact online classes. The study was conducted using an online survey of 107 university students attending metropolitan, local and foreign universities for a week from August 25th, 2020 to September 2nd, 2020. The analysis methods used included descriptive statistics and chi-square distribution, Fisher's exact test, linear by linear association, and logistic regression. The result of the study showed a significant decrease in Junior by 0.025 times compared to Senior (p<.05). Furthermore, a significant decrease in the impact of recorded lectures by 0.036 times compared to a hybrid of face-to-face and online lectures (p<.05). Compared to the response 'No', the number of student's responses of 'Yes' increased significantly by 31.358 times (p<.05). Additionally, a significant increase was seen in teaching methods by 19.709 times, and academic satisfaction by 7.989 times(p<.05). In conclusion, the results imply that the quality of lecture content is also important to improve the student's satisfaction with school life, but overall management is required in the areas of appropriate teaching methods, appropriate tuition, and evaluation methods.

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.13-20
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• 2022

IEEE 802.11ay Wi-Fi is the next generation wireless technology and operates in mmWave band. It supports the MU-MIMO (Multiple User Multiple Input Multiple Output) transmission in which an AP (Access Point) can transmit multiple data streams simultaneously to multiple STAs (Stations). To this end, the AP should perform MU-MIMO beamforming training with the STAs. For efficient MU-MIMO beamforming training, it is important for the AP to estimate signal strength measured at each STA at which multiple beams are used simultaneously. Therefore, in the paper, we propose a deep learning-based link quality estimation scheme. Our proposed scheme estimates the signal strength with high accuracy by utilizing a deep learning model pre-trained for a certain indoor or outdoor propagation scenario. Specifically, to estimate the signal strength of the multiple concurrent beams, our scheme uses the signal strengths of the respective single beams, which can be obtained without additional signaling overhead, as the input of the deep learning model. For performance evaluation, we utilized a Q-D (Quasi-Deterministic) Channel Realization open source software and extensive channel measurement campaigns were conducted with NIST (National Institute of Standards and Technology) to implement the millimeter wave (mmWave) channel. Our simulation results demonstrate that our proposed scheme outperforms comparison schemes in terms of the accuracy of the signal strength estimation.

• Journal of Korea Entertainment Industry Association
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• v.13 no.6
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• pp.25-32
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• 2019

According to a recent KOFICE survey, K-Pop's popularity factor is divided into visual and auditory elements, and the importance of hearing elements is found. Among the various types of singers, idol groups led K-Pop and Black Pink, which topped the list of favorite K-Pop singers in 2018, was selected as the study target. In addition, Twice's music, which is similar to Black Pink's period of activity, has been set as a comparative research scope. The common features in the music of the two groups are the chorus and rhythm structure implemented around melody and Harmony rhythm, and the frequency of use of Major and Minor is greatly different. Through this method and modal interchange, K-Pop from 2016 to 2018 is analyzed. Research shows that first, more than one mode is used as a main melody. When more than one mode is used, different lines in the same line will vary depending on the functional form of the song. Second, the rhythm of the melody expressed with vocals and instruments is repeated based on a two-bar pattern. Finally, when using less chord and slowly expressing the igneous rhythms, there is a way to omit or modify the third notes that determine chord characteristics. Through this study, we can see that the usage patterns of the mode and modal interchange are divided according to the major and minor.