• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.120-127
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• 2009

This paper proposes a new Pulse Frequency Modulation(PFM)-Series Boost Capacitor(SBC) full bridge DC/DC Converter which features a high efficiency and high power density. The proposed converter controls the output voltage by varying the voltage across the series boost capacitor according to switching frequency and has no freewheeling period due to 50% fixed duty operation. As a result, its conduction loss is lower than that of the conventional phase shift full bridge converter. Moreover, ZVS of all power switches can be ensured along wide load ranges and output current ripple is very small. Therefore, it has very desirable merits such as a small output inductor, high efficiency, and improved heat generation. This paper performs a rationale and PSIM simulation of the proposed converter. Finally, experimental results from a 1.2kW(12V, 100A) prototype are presented to confirm the operation, validity and features of the proposed converter.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.151-160
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• 2010

For the realization of future intelligent transportation systems, fine-grained lane-by-lane traffic monitoring and control functionalities are among the most important technology barriers to overcome. To satisfy the accuracy requirement for traffic monitoring, a GNSS receiver network is designed. The designed receiver network consists of three different types of entities; reference server, broadcaster, and client. For deployment flexibility, all the entities utilize the international message standard RTCM SC-104 version 3.0. For fine-grained traffic monitoring, the client is designed to utilize position-domain carrier-smoothed-code filters to provide accurate vehicle coordinates in spite of frequent addages and outages of visible satellites. An experiment result is presented to evaluate the positioning accuracy of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.740-743
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• 2012

The initial role of the operating system acts as an intermediary between the computer and the user, and, hardware and process management, and the convenience of your computer system is to use. Of these operating systems as well as servers and personal computers, smartphones and tablet mounted on mobile devices such as mobile operating system was born. Mobile Operating System has been expanded a TV or Car Area that built into a simple embedded operating system, is emergence of a variety of devices, cloud services, combined with the desire of users due to the high built-in simple embedded operating system that was working on a TV or a car is expanding to the area. The reason for the emergence of a variety of devices, cloud services, combined with the desire of users is high. In this paper, the mobile operating system, N-Screen, Smart TV to find out about and through the analysis of the major smart TV, the future Find out about trends in the mobile operating system.

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.23-30
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• 2017

For enjoying the convenience provided by location based services, the user needs to submit his or her location and query to the LBS server. So there is a probability that the untrusted LBS server may expose the user's id and location etc. To protect user's privacy so many approaches have been proposed in the literature. Recently, the approaches about using dummy are getting popular. However, there are a number of things to consider if we want to generate a dummy. For example, when generating a dummy, we have to take the obstacle and the distance between dummies into account so that we can improve the privacy level. Thus, in this paper we proposed an efficient dummy generation algorithm to achieve k-anonymity and protect user's privacy in LBS. Evaluation results show that the algorithm can significantly improve the privacy level when it was compared with others.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.276-287
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• 2004

An ad hoc network is infra(Base Sstation or Access Point) free wireless mobile communication technology. Mobile nodes function as routers and servers in ad hoc networks. Many routing protocols for ad hoc network have been proposed. If any route is broken owing to moving node, source must repair broken route again. But route repair technology after route collapses is not suitable to transmit real-time data packet for QoS guarantee. So this paper presents route repair technology that prevents route from breaking. If intermediate node moves to critical section, the node issues handoff packet and sends the packet to the next node. After next node receives handoff packet, the node broadcasts route request packet to the previous node for intermediate node. Finally, even if intermediate node moves out of the routing region, the source can continuously transmit data packets to the destination through the new path.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.947-954
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• 2009

In mobile ad hoc networks, service discovery to search for an available service is an important issue. In this paper, we propose an efficient service discovery protocol that is combined a dht-based service discovery scheme and a P2P caching-based information spreading scheme. Proposed scheme store key information in hashed zone and search services using it's information. To search quickly a service, it use its physical neighbors information which collected by 1-hop hello message between a node and its physical neighbors. We do not use a central look up server and do not rely on flooding. Hence, it uniquely balanced all node's load in mobile ad hoc networks and reduced the number of messages exchanged, network load and response time. The simulation results show that our protocol outperforms DHT-based and flooding protocols.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.143-148
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• 2016

There is increasing concern about security as a need for increased safety in the information industry society. However, it does not meet the needs for safety including CCTV. Therefore, in this paper, we link the processing technology using the image information to the IPS system consisting of GPS and Beacon. It designed a conventional RFID tag attached discomfort and image tracking system is limited to complement the disadvantages identifiable area. To this end, we designed a smart device and the Internet of Things convergence system and a research to ensure the accuracy and reliability of the IPS of the access control system. Finally, by leveraging intelligent video information using a PTZ camera, and set the entrant management policies it was carried out to control the situation and control. Also, by designing the integrated video tracking system, an authentication server, visualization systems were designed to establish an efficient technique for analyzing the IPS entrant behavior patterns.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.29-37
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• 2011

As the area of informatization has been expanding followed by the development of information communication technology, cloud computing which can use infra sources like server, storage, and network in IT area as an efficient service whenever and wherever skyrockets. But users who use cloud computing technology may have some problems like exposure personal data, surveillance on person, and process on commercial purpose on their personal data. This paper proposes a security technique which protect user's privacy by creating imaginary user information not to be used by other people. The proposed technique virtualizes user's information as an anonymity value not to let other people know user's identity by combining PIN code with it and guarantees user's anonymity. Also it can manage and certificate personal information that is important in cloud computing, so that it can solve security problem of cloud computing which centers all informations. Therefore this paper can assist upgrading of the level of information of poor SMBs through safe use of cloud computing.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.491-496
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• 2015

Cloud computing has emerged with promise to decrease the cost of server additional cost and expanding the data storage and ease for computer resource sharing and apply the new technologies. However, Cloud computing also raises many new security concerns due to the new structure of the cloud service models. Therefore, the secure user authentication is required when the user is using cloud computing. This paper, we propose the enhanced AdaBoost algorithm for access cloud security zone. The AdaBoost algorithm despite the disadvantage of not detect a face inclined at least 20, is widely used because of speed and responsibility. In the experimental results confirm that a face inclined at least 20 degrees tilted face was recognized. Using the FEI Face Database that can be used in research to obtain a result of 98% success rate of the algorithm perform. The 2% failed rate is due to eye detection error which is the people wearing glasses in the picture.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.294-296
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• 2017

Cloud computing is a computing technique that uploads all the data from a cloud node to a cloud server and provides it to users as a service. This is difficult to provide services in real time depending on the network conditions. This is because it is necessary to download information to the remote site through the network, not the local area, and to download additional services to provide services in the cloud. So fog computing has been proposed as an alternative. In this paper, we propose an efficient data exchange technique between cloud, fog and user. The proposed fog provides services to users and collects and processes data. The cloud is responsible for the flow of data exchange and control between the fog. We propose a standard method for data exchange. The application for this is to process and service the information generated by the BAN (Body Area Network) in the fog, and the cloud serves as a mediator. This can resolve data heterogeneity between devices or services and provide efficient data movement.