• Smart Structures and Systems
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• v.6 no.3
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• pp.183-196
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• 2010

Monitoring and economical design of alternative energy generators such as wind turbines is becoming increasingly critical; however acquisition of the dynamic output data can be a time-consuming and costly process. In recent years, low-cost wireless sensors have emerged as an enabling technology for structural monitoring applications. In this study, wireless sensor networks are installed in three operational turbines in order to demonstrate their efficacy in this unique operational environment. The objectives of the first installation are to verify that vibrational (acceleration) data can be collected and transmitted within a turbine tower and that it is comparable to data collected using a traditional tethered system. In the second instrumentation, the wireless network includes strain gauges at the base of the structure. Also, data is collected regarding the performance of the wireless communication channels within the tower. In both turbines, collected wireless sensor data is used for off-line, output-only modal analysis of the ambiently (wind) excited turbine towers. The final installation is on a turbine with embedded braking capabilities within the nacelle to generate an "impulse-like" load at the top of the tower. This ability to apply such a load improves the modal analysis results obtained in cases where ambient excitation fails to be sufficiently broad-band or white. The improved loading allows for computation of true mode shapes, a necessary precursor to many conditional monitoring techniques.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.589-594
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• 2012

In the initial stage, domestic games based online concentrated on game development focusing on income for some genres. However, various contents focusing on smart environment and social network are expanded at present and game materials are developed for more various objects. So, this study intends to examine new category, positive game, from the aspect of game designer for game approach based on various objects. And, game approaching process in the category based on pleasure was organized from the standpoint of designer, for the designer approach in the precedent stage of positive game development. From the aspect of designer, systemicity of game category and design approach are necessary to expand wire-wireless environment and new environment based on the convergence media to interactive contents focusing on games.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.211-218
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• 2018

Recently, various technologies related to IIoT are introduced continuously due to the spread of IoT and smart factory industries. This paper proposes the construction of a two-way wireless network system for monitoring plant equipment using these various technologies. The main technologies used in this thesis are design techniques for micro sensor nodes to monitor facility conditions at various sites, MQTT technology for wireless communication between local server and sensor nodes and Node-RED based design technologies, which store data collected and can be easily presented to users via wired and wireless wires. In addition, a wireless two-way camera system was also implemented in which the screen images of the site can be viewed in the situation room according to the instructions of the situation room when determining abnormal conditions.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.105-110
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• 2016

As smart devices have proliferated and network speed and accessibility of mobile have accelerated, mobile cloud services that can do the same tasks by various devices are promoted. This paper explores the analysis of use intention of mobile cloud services and influencing factors. We develop and apply a convergence technology acceptance model which combines TAM, VAM and UTAUT. The proposed model verifies some hypotheses to aware the significant factors of use intention of mobile cloud services with TAM, VAM and UTAUT including additional mobile cloud service characteristics such as mobility, high availability, easy accessibility and scalability. Eventually, this research can not only help users gain insights into mobile cloud service use intention, but also help mobile cloud service providers to develop more effective mobile cloud service and their business strategy in the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.281-286
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• 2017

SNS is a platformwhere users build a social relationship and share opinions and informations. To do these, it supports a text, an image and a video data. As it is possible to exploit the location data of a smart device, SNS tries to use the location data. However,since SNS does not support the coordinate data, it provides the restricted function sharing the image map instead of the vector map. In this paper, we propose a chatting systemsharing pathsto support the coordinate data on a classical SNS. On the proposed system, it is possible for usersjoined in a roomto watch a vector map of same area and exchange texts. If a user builds a path on the map, the system propagates the coordinate data of the generated path and the other users joined in the room watch the path immediately. The implemented chatting systemhasthe benefit to share the information related a map between users using coordinate data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.661-666
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• 2016

The Internet of Things (IoT) is an infrastructure of physical objects that could be connected to the Internet. Most of these are low performance to ensure a reasonable cost for the smart physical objects. Thus, these devices usually use a lightweight messaging protocol: message queue telemetry transport with SSL/TLS. Cipher suites in device are fixed by default and selected based on preference in SSL/TLS. However, the selected cipher suite provides high security level more than expected. This limitation causes energy waste and overhead of devices. In order to counter this problem, we proposed fuzzy logic based cipher suite decision method to improve energy efficiency. Our proposed method saved 36.03% energy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1051-1053
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• 2015

Twitter is using Tweets to post 140 characters at a time to interact with different people around the world. In addition, Twitter will also provide speed, such as instant messaging by providing the follow feature. This was used for increasing the number of users because of the tweeter, a portion of the life was due to the popularity of smart phones. However, because of the large amount of data of the tweeter has a disadvantage similar to the user information or user information is not recommended. In this paper, in order to compensate for this problem to establish a ranking filter the similarity information based on a user's system, we propose that the user or the like similar to the user information. The system proposed in this paper consists of the collected data and modules to collect data using a user account in the filtering and the like to the tweeter module. These modules use the Open API and Mahout designed and implemented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.17-25
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• 2018

Recently, with the development of ICT technology and the rapid spread of smart devices, a huge amount of information is being generated. The recommendation system has helped the informant to judge the information from the information overload, and it has become a solution for the information provider to increase the profit of the company and the publicity effect of the company. Recommendation systems can be implemented in various approaches, but social information is presented as a way to improve performance. However, no research has been done to utilize trust cluster information among users in the recommendation system. In this paper, we propose a method to improve the performance of the recommendation system by using the influence between the intra-cluster objects and the information between the trustor-trustee in the cluster generated in the online review. Experiments using the proposed method and real data have confirmed that the prediction accuracy is improved than the existing methods.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.9
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• pp.341-348
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• 2014

The advance in web accessibility with dissemination of smart phones gives rise to rapid increment of users on social network platforms. Many research projects are in progress to detect events using Twitter because it has a powerful influence on the dissemination of information with its open networks, and it is the representative service which generates more than 500 million Tweets a day in average; however, existing studies to detect events has been used TFIDF algorithm without any consideration of the various conditions of tweets. In addition, some of them detected predefined events. In this paper, we propose the RTFIDF VT algorithm which is a modified algorithm of TFIDF by reflecting features of Twitter. We also verified the optimal section of TF and DF for detecting events through the experiment. Finally, we suggest a system that extracts result-sets of places and related keywords at the given specific time using the RTFIDF VT algorithm and validated section of TF and DF.

• Journal of Digital Contents Society
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• v.12 no.3
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• pp.383-390
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• 2011

The purpose of this study was to examine major motivations for using SNSs and the effect of them on SNS participation. In order to address the research questions, 253 undergraduate and graduate students participated. Results of the study were summarized as follows. First, Cyworld was mainly used followed by Facebook and Twitter. Most of the respondents had access to SNSs via smart devices. The average frequency of SNS use was 1-3 times a day and they used them less than 30 minutes a time. The reasons why they started to use SNSs were mainly to follow current trends, maintain friendship, and accept acquaintances recommendations. Second, the result of component analysis derived four primarily underlying dimensions related to SNS use; self-satisfaction, social interaction, recreation, and information seeking. Third, both self-satisfaction and social interaction motivation had significant correlation with SNS participation. The results of multiple regression analysis showed that self motivation was more influential on active participation than social interaction and information seeking motivation.