• 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.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.297-302
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• 2015

The increase in applying IT to vehicles has given birth to smart cars or connected cars. As smarts cars become connected with external network systems, threats to communication security are on the rise. With simulation test results supporting such threats to Convergence security in vehicular communication, concerns are raised over relevant vulnerabilities, while an increasing number of studies on secure vehicular communication are published. Hacking attacks against vehicles are more dangerous than other types of hacking attempts because such attacks may threaten drivers' lives and cause social instability. This paper designed a Convergence security protocol for inter-vehicle and intra-vehicle communication using a hash function, nonce, public keys, time stamps and passwords. The proposed protocol was tested with a formal verification tool, Casper/FDR, and found secure and safe against external attacks.

• Smart Structures and Systems
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• v.17 no.2
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• pp.167-194
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• 2016

This paper investigates the Synergetics based Damage Detection Method (SDDM) for frame structures by using surface-bonded PZT (Lead Zirconate Titanate) patches. After analyzing the mechanism of pattern recognition from Synergetics, the operating framework with cooperation-competition-update process of SDDM was proposed. First, the dynamic identification equation of structural conditions was established and the adjoint vector (AV) set of original vector (OV) set was obtained by Generalized Inverse Matrix (GIM).Then, the order parameter equation and its evolution process were deduced through the strict mathematics ratiocination. Moreover, in order to complete online structural condition update feature, the iterative update algorithm was presented. Subsequently, the pathway in which SDDM was realized through the modified Synergetic Neural Network (SNN) was introduced and its assessment indices were confirmed. Finally, the experimental platform with a two-story frame structure was set up. The performances of the proposed methodology were tested for damage identifications by loosening various screw nuts group scenarios. The experiments were conducted in different damage degrees, the disturbance environment and the noisy environment, respectively. The results show the feasibility of SDDM using piezoceramic sensors and actuators, and demonstrate a strong ability of anti-disturbance and anti-noise in frame structure applications. This proposed approach can be extended to the similar structures for damage identification.

• Journal of the Korea Society of Computer and Information
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• v.18 no.5
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• pp.103-111
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• 2013

This paper provide a framework for an IGILMS(internet-based global integrated logistics management system) which can access and mediate cargo transportations among small- and medium-sized domestic/international logistics corporations as regards cargo, registration and search for space, public tender and negotiation, contract, payment and safety-guarantee, transportation through the internet, wireless communication means, or smart phone etc. In addition, we describe a model to provide customized services in the B2B e-market for IGILMS and the structure and the control of its fulfillment process, and provide technical architecture of the IGILMS for an internet-based global logistics management system. To validate an efficiency of the proposed system, we develop a simulation model and analyze the performance of the proposed system.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.57-66
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• 2012

LTE-Advanced network will form the high-speed IP backbone in collaboration with heterogeneous radio access networks for dynamic optimized resource utilization. In order to implement more innovative and attractive services such as U-Cloud streaming, LBS and mobile smart TV, a mobile terminal needs to support multiple sessions simultaneously. Efficient resource allocation schemes are necessary to maintain QoS of multiple sessions because service continuity may be defected by delay and information loss during handover. This paper proposes a resource allocation scheme to accommodate multiple sessions in a mobile terminal on handover period based on session priority mechanism. Simulation is focused on the forced termination probability of handover sessions. Simulation results show that our proposed method provides a better performance than the conventional method.

• The Journal of Bigdata
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• v.5 no.1
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• pp.89-96
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• 2020

Deep learning using an artificial neural network has been recently researched and developed in various fields such as image recognition, big data and data analysis. However, federated learning has emerged to solve issues of data privacy invasion and problems that increase the cost and time required to learn. Federated learning presented learning techniques that would bring the benefits of distributed processing system while solving the problems of existing deep learning, but there were still problems with server-client system and motivations for providing learning data. So, we replaced the role of the server with a blockchain system in federated learning, and conducted research to solve the privacy and security problems that are associated with federated learning. In addition, we have implemented a blockchain-based system that motivates users by paying compensation for data provided by users, and requires less maintenance costs while maintaining the same accuracy as existing learning. In this paper, we present the experimental results to show the validity of the blockchain-based system, and compare the results of the existing federated learning with the blockchain-based federated learning. In addition, as a future study, we ended the thesis by presenting solutions to security problems and applicable business fields.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.159-167
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• 2015

The nature of port logistics requires global visibility and traceability. However, the traditional RFID technology still applied cannot meet these demands. IP-USN and M2M in port logistics have faced challenges of the prerequisite of network composition and immense communications at the base where a grand number of containers are installed. To resolve the issue, this study suggests an IP-RFID-based smart port logistics service platform. The IP-RFID-based port logistics service system resolved the communication problem by separating the RFID tag and AP, which allows internet connection, from the tag. The tags connected with thermo-sensors, humidity sensors, pressure sensors, GPS, etc. are attached to the containers insuring global visibility and traceability, key factors in logistics, by obtaining desired real-time information regardless of time and location.

• Journal of Digital Contents Society
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• v.15 no.1
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• pp.113-120
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• 2014

In recent years, devices using the smart ponwa IT service is activated, to research how the fusion of two or more devices will be able to be interest in the soybeans. One of them in the mobile sector through the development of network and hardware digital geo-spatial map of the rapid advances being made and the computer, how do you map data to efficiently simulate a 3D environment, providing services through a virtual environment focused on whether be. In this study, augmented reality and GIS (Geographic Information System), SLM (Static LOD Model) that combines augmented reality technology on the basis of the basic concepts and approaches in geographic space and how Augmented Reality Based on this interpretation of the relevant content What to do in the development and utilization has a purpose. In this study, the conventional SLM 3DS model data structure of a data format conversion of the proposed possibilities for analyzing and, SLM model generation and format of the existing three-dimensional visualization tools SLM model format for converting a format to a model function, and visualization features. In addition, 3D virtual model to propose a format for efficiently making.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.113-122
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• 2020

In this paper, we propose the terminal authentication system using blockchain and TOTP(Time-based One-time Password Algorithm) to sustain a continuous authentication between user device and service device. And we experiment this system by using door-lock as a terminal of IoT(Internet of Things). In the future, we can apply this result to several devices of IoT for convenience and security. Although IoT devices frequently used everyday require convenience and security at the same time, it is difficult for IoT devices having features of the low-capacity and light-weight to apply the existing authentication technology requiring a high amount of computation. Blockchain technology having security and integrity have been used as a storage platform, but its authentication cannot be performed when the terminal cannot access any network. We show the method to solve this problem using Blockchain and TOPT.