• Journal of Communications and Networks
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• v.17 no.6
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• pp.568-581
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• 2015

Predicting locations of users with portable devices such as IP phones, smart-phones, iPads and iPods in public wireless local area networks (WLANs) plays a crucial role in location management and network resource allocation. Many techniques in machine learning and data mining, such as sequential pattern mining and clustering, have been widely used. However, these approaches have two deficiencies. First, because they are based on profiles of individual mobility behaviors, a sequential pattern technique may fail to predict new users or users with movement on novel paths. Second, using similar mobility behaviors in a cluster for predicting the movement of users may cause significant degradation in accuracy owing to indistinguishable regular movement and random movement. In this paper, we propose a novel fusion technique that utilizes mobility rules discovered from multiple similar users by combining clustering and sequential pattern mining. The proposed technique with two algorithms, named the clustering-based-sequential-pattern-mining (CSPM) and sequential-pattern-mining-based-clustering (SPMC), can deal with the lack of information in a personal profile and avoid some noise due to random movements by users. Experimental results show that our approach outperforms existing approaches in terms of efficiency and prediction accuracy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1420-1425
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• 2015

Lately, information and communications environmentis in accordance with the smartphone release is changing the paradigm of working environments setting a high value on mobility and efficiency as well as the ecosystem of information and communication technologies. In this paper, we proposed smart work-based IT system modeling suitable for SMEs in order to transform the paradigm of working environments, strengthen the competitiveness of SMEs, and to establish a foundation on which SMEs could leap to the global economy, by fostering the acceleration of information service implementation and smart work foundation. We conducted a survey of the change in awareness and creation of smart work environment targeting companies with less than thirty workers and proved it. will also contribute to smart work diffusion in SMEs by drawing a positive result of more than 75%.

• Korean Journal of Materials Research
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• v.31 no.7
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• pp.397-402
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• 2021

In this study, binderless-WC, WC-6 wt%Co, WC-6wt% 1 and 2.5 B₄C materials are fabricated by spark plasma sintering process (SPS process). Each fabricated WC material is almost completely dense, with a relative density up to 99.5 % after the simultaneous application of pressure of 60 MPa. The WC added Co and Co-B₄C materials resulted in crystalline growth. The WC with HCP crystal structure has respective interfacial energy (basal facet direction: 1.07 ~ 1.34 J·m^-2, prismatic direction: 1.43 ~ 3.02 J·m^-2) that depends on the grain growth direction. It is confirmed that the continuous grain growth, biased by the basal facet, which has relatively low energy, is promoted at the WC/Co interface. As abnormal grain growth takes place, the grain size increases more than twice from 0.37 to 0.8 um. It is found through analysis that the hardness property also greatly decreases from about 2661.4 to 1721.4 kg/mm², along with the grain growth.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.129-137
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• 2022

Recently, the technology of aircraft drivers has been transitioning from the existing hydraulically-focused mechanical system to an all-electric one due to the high precision and ease of maintenance of electric drivers. Consequently, the failure of an aircraft's electric motor can have fatal consequences. To ensure aircraft safety, efficient and timely fault diagnosis methods are required prompting the active pursuit of research into fault diagnosis technology. This paper introduces and analyses the failure types and failure diagnosis technology trends of permanent magnet synchronous motors among electric motors.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.219-225
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• 2022

Recently, the popularization of personal mobility(PM) has made it possible to see many electric scooters. The energy source of personal transportation used by the general public and the disabled can be seen as environmentally friendly as electricity. Personal transportation means are divided into small electric vehicles because they use electric energy, and they are being treated as new models by automobile manufacturers in each country and spurring development. On the other hand, personal transportation means may cause various types of traffic accidents as they travel between roads and a human walk. In order to prevent such accidents, it is judged that the enactment of laws on the establishment of specifications for electric scooters, which are personal transportation means, and the method of restricting road operation should be given priority. The electric scooter is basically different from the conventional vehicle. The steering shaft of the steering system applied to the electric scooter one to two is possible. 1 to 2 the front-wheel under the steering column is used. It is classified according to the number of wheel installed at the electric scooter is the vehicle body into 2 wheel - electric scooter, and 3 wheel - electric scooter and 4 wheel - electric scooter. In this study, we propose a steering shaft design model that can be applied to an electric scooter, one of personal transportation means. A design model for 1-shaft steering and 2-shafts steering that can be applied to electric scooters is proposed. In addition, we have produced the prototypes for the commercialization of the proposed models, and reviewed the pros and cons of the manufactured prototypes and models.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.43-55
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• 2019

Smart phone based navigation applications are very useful in everyday life. Cost-effective and user friendly navigation can be provided to the user by many applications available in market. Using the Smart phone these navigation applications provide accurate navigation for outdoor locations. But providing an accurate navigation underground space such as subway station is still a challenge. It is hence more convenient and appropriate for mobility services if the visitors could simply view the guidance of the subway station on their mobile phone, wherever and whenever it is needed. This study develops a algorithm for indoor navigation with the help of Augmented Reality(AR) and QR marker code from the entrance to the train platform for users. This indoor navigation uses AR and QR maker codes for two purposes: to provide the user link to the subway station location and to provide the current guidance details to the user. This Smart phone algorithm that uses a smart phone optical tool to decode the QR marker to determine the location information and provide guidance to the AR without indoor Maps. This algorithm also provides a module to guide mobility vulnerable to the Barrier Free route to destination.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.21-28
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• 2022

The increase in the number of large cities and the size of their population sharpens attention to the new role of cities as entities to ensure a high-quality, safe and modern life of citizens, which has become significantly more active in recent years. The rapid spread of smart cities in the modern world has actualized the issue of analyzing their success and assessing the role of various factors in this. Every success of a smart city is always the result of a unique combination of the most modern technologies, environmental and social initiatives, skillful and consistent management, as well as available human potential. The purpose of the article is to analyze the success factors of smart cities based on the generalization of the results of the most famous ratings. In order to identify the impact of various factors, primarily intellectual, on the success and leadership positions of smart cities, the following ratings were consistently analyzed: Smart City Index (SCI), City in Motion Index (CIMI), Global Power City Index (GPCI), Global Cities Index (GCI), Global Cities Outlook (GCO). They have a different list of indicators and main pillars (dimensions), but all ratings take into account aspects such as: governance, ICT, mobility, functionality, human capital, etc. The highest correlation coefficient, that is, the strongest linear relationship of the CIMI index was found with such factors as: Human capital, Economy, Governance and Technologies. Summarizing the results of the TOP 20 smart cities according to different ratings allowed us to confirm that the list of leaders is very similar in all ratings. Among those cities that are in the TOP-20 in all five indexes are: London, Sydney and Singapore. There are four indices: New York, Paris, Tokyo, Copenhagen, Berlin, Amsterdam, Melbourne. Achieving leadership positions in smart city rankings is always the result of a combination and synergy of certain factors, and first of all, it is the quality of human capital. The intensity and success of the use of information and communication technologies in locality management processes, city planning and improvement of the city's living conditions depend on it.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.1020-1024
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• 2014

The environment information such as dust, temperature, humidity, illumination and gas are very important in daily life. We implemented multi-sensor system which made for measuring an environment by using Arduino, ZigBee, and Appinventor. We also designed a packet for transmitting environment data. The data are sent to the server via ZigBee and then it communicates to a smart phone via WI-Fi. In this study, we added divers sensors, designed a protocol which made for transfer several kinds of data and improve mobility for real time monitoring by using smart phones. The system was worked well and the data was transmitted correctly to the smart phone.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.644-654
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• 2013

It is required for enterprises to construct the proper information management system in order to cope with the volatile business situations. The mobile office system is introduced from the needs to provide organization members smart information and mobility. By setting the model, hence, we intend to scrutinize the impact of the task-technology fit model and organizational characteristics of the mobile office system on the job performance. As a result, system quality, information quality and mobility are revealed to affect positively the task-technology fitness and the fitness also affects the job performance positively. Organization characteristics affects the job performance positively through the task-technology fitness, too. Therefore the organization which plans to introduce the mobile office system should consider the task-technology fitness and exert organizational-level efforts to adopt and use the mobile office system in the workplace.

• Journal of KIISE:Information Networking
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• v.37 no.2
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• pp.99-108
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• 2010

The Wireless Ad Hoc network is discussed as a core technology for ubiquitous computing, and the smart tag technology is currently being actively discussed as a part of the sensor network. Thus, considering its security may advance the realization of ubiquitous computing. RFID (Radio Frequency Identification) technology using the smart tag technology as a part of the sensor network is currently in the limelight. In particular, when RFID is applied to a knowledge management system managing various data, data mobility and management convenience are ensured and automated knowledge service can be provided to users. Accordingly, this paper to proposed a secure scheme for mobility knowledge management systems using multi-agents differentiated from the existing knowledge management systems. Specifically, the proposed scheme designates user's authentication and privilege information in multi-agents and provides effective knowledge service through grouping based on user information. Moreover, even user's movement, the proposed scheme ensures service availability and provides continuous information through communication with multi-agent systems.