• Journal of Information Technology Services
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• v.16 no.4
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• pp.223-234
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• 2017

The audible pedestrian signal (APS) is an add-on device which connects to the pedestrian signaling device and informs the contents and changes of the signaling by sound. It provides walking direction information of the pedestrian crossing so that the blind people can safely cross the pedestrian crossing. In an intersection where a plurality of audible pedestrian signal (APS) are installed at an intersection crosswalk, existing audible pedestrian signal (APS) operate simultaneously in the communication radius of a wireless remote controller, which may cause confusion for the blind people and the public may complain about the noise. In this paper, we developed a BLE (Bluetooth Low Energy)-based audible pedestrian signal (APS) system capable of supporting two-way communications with a smart-phone that can cross the intersection safely and improve the walking comfort and traffic safety for the blind people. The proposed method is a method in which the BLE beacon communication based audible pedestrian signal (APS) presents active service to the blind people, and the existing audible pedestrian signal (APS) is a way of requesting the passive service by the blind people with the wireless remote control by the unidirectional communication based on 358Mhz. The developed system is installed in the crossroad of Doma-dong, Seo-gu, Daejeon, and it is tested and operated by the blind people. The satisfaction evaluation and analysis of the audible pedestrian signal (APS) for the blind people have good results and are planned to be expanded in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.75-76
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• 2016

Even if ICS(Interference Cancellation System) repeater is used in wireless communication system, it has the disadvantage that it must have enough distance between Donor and Service antenna to be isolated. In this paper, new ICS repeater integrated antenna with high insolation characteristics is designed. The proposed antenna is fabricated for 800MHz and measured. Bandwidth and gain are optimized by changing the stub lengths near main patch and power divider, and also by changing the size of parasitic patch. This antenna has a return loss less than -13 dB, a gain over 3 dBi, and an isolation between the donor and the server antennas less than -56 dB from 824~894 MHz for CDMA mobile communication. Therefore, the proposed antenna structure can be applied to eliminate the shadow area and to expand the coverage area for any other wireless communication bands.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.824-830
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• 2010

PLC_Zigbee system, implemented in a previous study, uses ZigBee Node based on PLC (Power Line Communication). The weak point of the system is that the long distance powerline communication and PLC is impossible to use in the areas where the powerline is not installed. In this paper, we added CDMA (Code Division Multiple Access) module using a data transfer method of SMS (Short Message Service) and XBee of WSN (Wireless Sensor Network) module to the previous system, and got around the restriction of place and environment of PLC system through the interfacing of each communication media. We, thus, implemented a wide range of real monitoring system.

• Journal of information and communication convergence engineering
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• v.12 no.4
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• pp.199-207
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• 2014

A new cooperative MAC protocol called the busy tone cooperative medium access control (BT-COMAC) protocol is proposed to overcome the drawbacks and maximize the advantages of existing schemes. This scheme uses a new metric called decibel power to decide an appropriate helper node. Using received power strength is more efficient in selecting an appropriate helper node, especially in a densely populated network, than the effective transmission rates used in conventional schemes. All communication nodes in a communication service area are assumed to move independently. Two performance metrics are used: System throughput and channel access delay. A performance evaluation of the BT-COMAC protocol is conducted using a computer simulation over a slow fading wireless channel, and its performance results are compared with those of four existing schemes. The numerical results show that the BT-COMAC protocol improves the system throughput by approximately 15% as compared to the best existing scheme.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.351-356
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• 2015

Visible light communication (VLC) is considered to be an attractive scheme to realize the broadband wireless communication for an indoor environment. We present a room division multiplexing (RDM) mechanism for an indoor multi-room VLC network, which utilizes the spatial position of the LED lamp in different rooms as a novel dimension of network resource for multiplexing, and thus the network capacity is increased. In such a network, the service interruption caused by user cross-room movement is an important problem, and we propose a double-area-positioning based cross-room switch solution. An experimental platform demonstrates the RDM-deployed VLC network, and validates the performance of the presented switch mechanism.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.211-217
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• 2009

In this paper, we discussed convergence in terrestrial broadcasting and wireless communication with respect to technology and service models. Especially, retrieval and relocation of TV broadcast spectrum after upcoming D-TV transition is investigated so that the benefit for broadcasting and communication industries as well as spectral efficiency to be maximized. Also, the role of TV broadcast spectrum as a utility for convergence of two industries is investigated based on open spectrum, open platform and open application initiatives.

• Journal of Korea Spatial Information System Society
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• v.3 no.1 s.5
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• pp.63-73
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• 2001

The purpose of this study is to develop a method of integrating diverse communication networks for effectively providing ITS(Intelligent Transport System) services. In this paper, in oder to integrate communication networks, we have defined ITS services, its requirements and functions of communications. Also, we have analyzed the six important ITS services in the National ITS Architecture along with the characteristics of wireless communications. Based on the ITS service scenarios, we have derived the communication methods for ITS services.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.366-372
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• 2002

Tele-medicine and emergency medical system are necessary for moving from an accidental point or far distance to a hospital and emergency treatment or home treatment before a hospital. Emergency treatment is extremely important in the case of death before arriving a hospital and deformed or disabled by medical treatment delay. A necessary element for this medical system is the emergency communication system. This system is on preparing for an ability of furnishing patient status to a corresponding health service by monitoring the patient at an ambulance of the accident place. This is the transportation of basic biological information of a patient to a medical center by wireless communication system and the corresponding hospital or medical center examine the patient by monitoring, then they can send emergency medical order to the patient for emergency treatment. The TRS is most efficient way of emergency medical communication system, which is currently used with popularity. In this paper studied simultaneously a way of detecting and transporting bio-logical signals, and monitoring of transporting data with communication of voice in the accident place or ambulance.

• Annual Conference of KIPS
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• 2007.11a
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• pp.819-822
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• 2007

최근 유비쿼터스 환경 실현을 위해서 무선 센서 네트워크에 관한 많은 연구가 진행되고 있다. IEEE 802.15.4 에 기반한 ZigBee 에 관한 연구는 이미 많은 진행이 되어 있다. 최근에는 IPv6 기술이 이슈화 되면서 무선 센서 네트워크 환경에도 IPv6 주소를 사용 할 수 있을 것으로 기대되고 있다. 본 논문에서는 IPv6 주소를 갖는 센서가 서비스를 제공하기만 하는 기존의 패러다임에서 벗어나 센서가 서비스를 찾는 모델을 제시한다. 그래서 IPv6 주소를 갖는 센서 네트워크의 보다 효율적인 서비스 디스커버리를 위해 객체 타입을 IPv6 주소의 일부분으로 정의해 준다. 이러한 객체타입을 이용한 IPv6 기반의 센서 네트워크의 효율성을 본 논문에서 검증한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.9-17
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• 2015

The development of wireless communication technology and change in the ICT market has led to the development of the M2M service and technology. Under these circumstances, the M2M environment has been the focus of communication environment construction between machines without control or direct intervention of human being. With characteristics of wireless communication environment, the possibility of being exposed to numerous security threats and safe communication security technology have becoming an issue an important requirements for problems such as data exposure, forgery, modulation, deletion, and privacy. This research analyzes requirements of trapdoor collision hash, generates keys between groups under the M2M environment by using the specificity of trapdoor, and suggests technology to exchange keys with session keys. Further, it also suggests techniques to confirm authentication of device and gateway in accordance with group key generation. The techniques herein suggested are confirmed as safe methods in that they have attack resistance such as Masquerade Attack, Man-in-the-Middle Attack, and Replay Attack in the group communication block by using the speciality of collision message and collision hash.