• Smart Structures and Systems
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• v.26 no.4
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• pp.419-433
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• 2020

Investigation of structural integrity has been a critical issue in the field of civil engineering for years. Visual inspection is one of the most available methods to explore deteriorative components in structures. Still, this method is not applicable to invisible damage of structures. Alternatively, system identification methods are capable of tracking modal properties of structures over time. The deviation of these dynamic properties can serve as indicators to access structural integrity. In this study, a modal tracking technique using frequency-domain system identification from seismic responses of structures is proposed. The method first segments the measured signals into overlapped sequential portions and then establishes multiple Hankel matrices. Each Hankel matrix is then converted to the frequency domain, and a temporal-average frequency-domain Hankel matrix can be calculated. This study also proposes the frequency band selection that can divide the frequency-domain Hankel matrix into several portions in accordance with referenced natural frequencies. Once these referenced natural frequencies are unavailable, the first few right singular vectors by the singular value decomposition can offer these references. Finally, the frequency-domain stochastic subspace identification tracks the natural frequencies and mode shapes of structures through quick stabilization diagrams. To evaluate performance of the proposed method, a numerical study is carried out. Moreover, the long-term monitoring strong motion records at a specific site are exploited to assess the tracking performance. As seen in results, the proposed method is capable of tracking modal properties through seismic responses of structures.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.187-193
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• 2021

Data conversion refers to the process of extracting the data existing in the existing system, that is, the past data accumulated by the old information system or other methods and transferring it to the improved table of the new system. The person in charge of data conversion refers to the entire process of converting to the final destination table according to the rules designed/planned in advance. In most cases, data conversion design should be consider when the old system replace or the data of another existing system is converted and applied to a newly constructed information system. The goal of data conversion is to understand the current database system of operating environment, understand the characteristics of the DBMS in use, maintain the optimal database structure, and make the new system perform at its best. Data conversion methods are largely divide into a method using a tool and a conversion method using a program preparation. In this paper, we examine the advantages and disadvantages of the data conversion method, and try to derive the problems of the existing data conversion method. Based on this, an improved data conversion method for the system upgrade project was proposed, and verified through a questionnaire of an IT expert to prove its effectiveness

• Information Systems Review
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• v.21 no.3
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• pp.131-149
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• 2019

As smart phones, tablets, and other digital devices become more pervasive, theoretical arguments around digital divide, which has previously focused on "access," is now expanding to effectively "utilize," actively "produce" and "share" information. Such discussion is significant because the impact on inter-personal and social networks depends on how digital divides are used, which can then recreate or exacerbate social inequality structures. This study examines the effect of individual's social relations and two types of social capital (i.e., bonding and bridging) on economic and socio-participatory usage of digital devices. An empirical analysis of dataset from 740 surveys reveals that the more horizontal the social relations of the individual, the more both bonding and bridging social capital increase. However, rather than the social relationship of the individual directly influencing the two types of digital device usage, it has an indirect effect on both economic and socio-participatory usage of digital devices. In particular, mediating effects of both bonding and bridging social capital exist in the case of economic usage of digital devices, whereas bonding social capital only has mediating effects on economic usage of digital devices. We discuss the role of social capital on digital devices usage and present the theoretical and practical implications.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.209-218
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• 2020

This paper investigated actual crop evapotranspiration (ET_c) of tomato and paprika planted in test beds of the greenhouse. Crop water requirement (CWR) is the amount of water required to compensate ET_c loss from the crop. The main objectives of the study are to assess whether the actual crop watering (ACW) was adequate CWR of tomato and paprika and which amount of ACW should be irrigated to each crop. ET_c was estimated using the Penman-Monteith model (P-M) for each crop. ACW was calculated from the difference of amount of nutrient supply water and amount of nutrient drainage water. ACW and CWR of each crop were determined, compared and assessed. Results indicated CWR-tomato was around 100 to 1,200 ml/day, while CWR-paprika ranged from 100 to 500 ml/day. Comparison of ACW and CWR of each crop found that the difference of ACW and CWR are fluctuated following day of planting (DAP). However, the differences could divide into two phases, first the amount of ACWs of each crop are less than CWR in the initial phase (60 DAP) around 500 ml/day and 91 ml/day, respectively. Then, ACWs of each crop are greater than the CWR after 60 DAP until the end of cultivation approximately 400 ml/day in tomato and 178 ml/day in paprika. ET_c assessment is necessary to correctly quantify crop irrigation water needs and it is an accurate short-term estimation of CWR in greenhouse for optimal irrigation scheduling. Thus, reducing ACW of tomato and paprika in the greenhouse is a recommendation. The amount of ACW of tomato should be applied from 100 to 1,200 ml/day and paprika is 100 to 500 ml/day depend on DAP.

• Journal of KIISE
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• v.44 no.1
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• pp.71-77
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• 2017

There has been a recent spate in the usage of mobile device equipped GPS sensors, such as smart phones. This trend enables the posting of geo-tagged messages (i.e., multimedia messages with GPS locations) on social media such as Twitter and Facebook, and the volume of such spatial data is rapidly growing. However, the relationships between the location and content of messages are not always explicitly shown in such geo-tagged messages. Thus, the need arises to reorganize search results to find the relationship between keywords and the spatial distribution of messages. We find the smallest minimum bounding rectangle (MBR) that embedding k or more points in order to find the most dense rectangle of data, and it can be usefully used in the location search system. In this paper, we suggest efficient algorithms to discover a group of 2-Dimensional spatial data with a close distance, such as MBR. The efficiency of our proposed algorithms with synthetic and real data sets is confirmed experimentally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.752-758
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• 2012

SNS(Social Networking Services) is oneline service that enable users to construct human network through their relation on web, such as following relation, friend relation, and etc. Recently, owing to the advent of digital devices (smart phone, tablet PC) which embedded GPS some applications which provide services with spatial relevance and social relevance have been released. Such an online service is called LBSNS. It is required to use spatial filtering so as to build the LBSNS system that enable users to subscribe information of interesting area. For spatial filtering, user and tweet attaches location information which divide into static property presenting fixed area and dynamic property presenting user's area changed along the moving user. In the case of using a location information including dynamic property, Continuous query occurred from the moving user causes the problem in server. In this paper, we propose spatial filtering algorithm using Virtual Grid for reducing frequency of query, and conclude that frequency of query on using Virtual Grid is 93% decreased than frequency of query on not using Virtual Grid.

• The Journal of the Korea Contents Association
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• v.14 no.12
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• pp.694-705
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• 2014

Recently media use is in the period of upheaval because of the advent of smart media. At this present, there are many discussions about the multiplexing or convergence of media use and these effects of everyday life, based on the theory of 'media repertoires'. But many researches just divide media repertoire categories and show media use hours by these categories. To have more mighty power of explanation, the study about media repertoires must execute both a static analysis of media use hours and a dynamic analysis of media use by media repertoire categories in everyday life.

• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.125-139
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• 2014

In this study, we're going to look at the formation process of Youth film Festival and factors affecting that process. The Youth film Festival didn't appear suddenly in a day. There have been various trial regarding media education by civil society organizations (NGO) until the mid 1990s, principal Youth film Festival has been held from 1997s to 2001s and established a framework for Youth film Festival. There were some progress after those times and then in 2008 Youth film Festival faced some changes such as screening online, and responded rapidly to the current image industry and the cultural stream like the appearance of HD camcoder and smart phone till now. We can divide two areas regarding factors that affecting those formation process of Youth film Festival. First, they are explained as economic and social factors that the situation of South Korea extremely such as the efforts of civil society organizations (NGO), image technology and development of the industry, IMF bailout era and so on, second cultural and educational factors that the rise of virtual culture, the University entrance and results of awards. Thus Youth film Festival has been evolved in various affects, so we can look into the various sections of korea society through these formation process of Youth film Festival.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.315-318
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• 2005

Recently, the advent of wireless communication and other handhold devices like Personal Digital Assistants and smart cards have made in implementation of cryptosystems a major issue. One important aspect of modern day ciphers is the scope for hardware sharing between the encryption and decryption algorithm. The cellular Automata which have been proposed as an alternative to linear feedback shift registers(LFSRs) can be programmed to perform the operations without using any dedicated hardware. But to generalize and analyze CA is not easy. In this paper, we characterizes uniform/hybird complemented group CA with rules 195/153/51 that divide the entire state space into smaller spaces of maximal equal lengths. This properties can be useful in constructing key agreement algorithm.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.5
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• pp.487-492
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• 2018

Recently, various applications for image processing have been ported to the mobile environment due to the expansion of the image shooting on the mobile device. However, in the case of extracting the image foreground, which is one of the most important functions of image synthesis, is difficult since it needs complex calculation. In this paper, we propose an video synthesis technique that can divide images captured by mobile devices into foreground / background and combine them in real time on target images. Considering the characteristics of mobile shooting, our system can extract automatically foreground of input video that contains weak motion when shooting. Using SIMD and GPGPU-based acceleration algorithms, SD-quality images can be processed on mobile in real time.