• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.565-570
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• 2015

In this paper, we implemented the smart door lock system that control remotely devices using the concept of internet of things. Internet of things is intelligent system that can help devices to communicate with people and devices. And recently internet of things is getting attention because of advance of hardware technology and big data. The smart doorlock system based on internet of things used raspberry pi, sensor and doorlock. Using the smart phone, doorlock can be controlled from the raspberry pi server. And the user can identify some people that is in front of doorlock. also user can check around of doorlock in realtime using the raspberry pi camera.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.387-395
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• 2005

In this paper, we propose an end-to-end mobility management and TCP flow control scheme which considers different link characteristics for vertical handover environments. The end-to-end mobility management is performed by using SIP protocol. When a mobile node moves to a new network, it informs its movement of the correspondent node by sending SIP INFO message containing a new IP address which will be used in the new network. And then the corresponding node encapsulates all packets with the new IP address and sends them to the mobile node. in general, RTT of WLAN is shorter than RTT of cdma2000. when the MN moves from WLAN network to cdma2000 network, TCP retransmission timeout will be occurred in spite of non congestion situations. Thus, TCP congestion window size will be decreased and TCP throughput will be also decreased. To prevent this phenomenon, we propose a method using probe packets after handover to estimate a link delay of the new network. We also propose a method using bandwidth ratio of each network to update RTT. It is shown through NS-2 simulations that the proposed schemes can have better performance than the previous works.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.116-120
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• 2011

In this paper, we have designed and implemented the integrated protocol gateway for the integration of CAN and Profibus networks. To do that, we used the Switched Ethernet as Backbone network, and each fieldbus network is connected by CAN/Ethernet or Profibus/Ethernet gateway, and each gateway perform the translation between fieldbus and Ethernet frames. Futhermore, we realized the real-time features in the environment of the Switched Ethernet by applying the distributed hard real-time scheduling algorithm among each gateways. To implement tht CAN/Ethernet and Profibus/Ethernet gateways, we used the Linux of kernel 2.6.31.12 real-time patched version(PREEMTED_RT), and we could verify successful message translation and real-time features through real implementation.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.4
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• pp.247-258
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• 2009

Distributed file systems running on a cluster of inexpensive commodity hardware are being recognized as an effective solution to support the explosive growth of storage demand in large-scale Internet service companies. This paper presents the design and implementation of BeanFS, a distributed file system for large-scale e-mail services. BeanFS is adapted to e-mail services as follows. First, the volume-based replication scheme alleviates the metadata management overhead of the central metadata server in dealing with a very large number of small files. Second, BeanFS employs a light-weighted consistency maintenance protocol tailored to simple access patterns of e-mail message. Third, transient and permanent failures are treated separately and recovering from transient failures is done quickly and has less overhead.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.123-124
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• 2012

Over the past decades, information and communication service providing safe and efficient navigation have been tried in maritime area. However, there were provided different ways such as different protocol or different policy. It made hard to serve efficiently. The introduction of MSI as a part of e-navigation development can be a kind of concepts to solve this problem. This paper tries to suggest a conceptual design of onboard application middleware to be able to communicate the shore-side maritime safety information system, take into account the reuse of open-source software.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.19-20
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• 2009

International Maritime Organization(IMO) recommends the installation of an Automatic Identification System(AIS) according to requirements by SOLAS Chapter 5 to avoid maritime collision. AIS provides traffic information of other ships that may be used for maritime traffic control, SAR(Search and Rescue) and collision avoidance to apply safety management. In this paper, preliminary results to implement an aeronautical surveillance transceiver using AIS transceiver based on ADS-B concepts are described. Although altitude information is not required for AIS since the AIS is operated at MSL(Mean Sea Level), altitude information can be extracted by a GPS chip-set in the ALS transceiver. ADS-B transceiver is implemented by defining a surveillance message format including the altitude information and modifying SOTDMA protocol. Ground tests and flight tests are performed to validate the implementation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2119-2124
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• 2016

The Internet of things (IoT) needs to be an event-driven approach for efficient related time response and processing. The growth of mobile devices in Internet of Things (IoT) leads to a number of intelligent buildings related IoT applications. For instance, home automation controlling system uses client system such web apps on smartphone or web service to access the home server by sending control commands. The gateway based RESTful technology responsible for handling clients'requests attests an internet latency in case a large number of clients' requests submit toward the gateway increases. In this paper, we propose the design tasks of the IoT gateway for handling concurrency events. The gateway based event-driven architecture is designed for building IoT gateway using node.js on one side and communication protocol based message-oriented middleware known as XMPP to handle communications of intelligent building control devices connected to the gateway through a centralized hub.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11S
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• pp.3603-3612
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• 2000

This paper presents is for the design and implementation of EDI document exchange system based on XML To create a customized document of the users' choice, it designed and created the transaction processor and the template manager, and to make it accessable with the original EDI, a converter function is included, Also, on this system, this protocol stores EDI message structure that needed to exchange as XML format and controls it as DOM API for user can use previous system, And provides interface for user can create template files with converter and transfer necessary elements that can be chosen by user. For this purpose, This system proposes a shows structure information and document converting mechanism solution of EDI documents based on by using XML which does not show proper document conversion mechanism solution in other system so far.

• The Journal of Information Technology
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• v.3 no.3
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• pp.117-134
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• 2000

Client-server DBMS based on a data-skipping model can exploit client resources effectively by allowing inter-transaction caching. However, inter-transaction caching raises the need of transactional cache consistency maintenance(TCCM) protocol, since each client is able to cache a portion of the database dynamically. Detection-based TCCM schemes can reduce the message overhead required for cache consistency if they validate clients replica asynchronously, and thus they cm show high throughput rates. However, they tend to show high ratios of transaction abort since transactions can access invalid replica. For coping with this drawback, this paper develops a new notion of shadow transaction, which is a backup-purpose one that is kept ready to replace an aborted transaction. This paper proposes a new detection-based TCCM scheme named DL-ST on the basis of the notion of shadow transaction. Using a simulation model, this paper evaluates the effect of shadow transaction in terms of transaction through rate and abort ratio.

• Journal of Internet Computing and Services
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• v.13 no.4
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• pp.95-102
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• 2012

The development of applications for vehicular ad hoc networks (VANETs) has very specific and clear goals such as providing intellectual safe transport systems. An emergency warning technic for public safety is one of the applications which requires an intelligent broadcast mechanism to transmit warning messages quickly and efficiently against the time restriction. The broadcast storm problem causing several packet collisions and extra delay has to be considered to design a broadcast protocol for VANETs, when multiple nodes attempt transmission simultaneously at the access control layer. In this paper, we propose an early intelligent alert broadcasting (EI-CAST) algorithm to resolve effectively the broadcast storm problem and meet time-critical requirement. The proposed algorithm uses not only the early alert technic on the basis of time to collision (TTC) but also the intelligent broadcasting technic on the basis of fuzzy logic, and the performance of the proposed algorithm was compared and evaluated through simulation with the existing broadcasting algorithms. It was demonstrated that the proposed algorithm shows a vehicle can receive the alert message before a collision and have no packet collision when the distance of alert region is less than 4 km.