• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2A
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• pp.86-95
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• 2003

With the advent of future mobile communication systems, the wireless transmission of the huge amount of multimedia data over the error-prone multipath fading channel has to overcome the inherent sensitivity to channel errors. To alleviate the effect of the channel errors, hosts of techniques based on the forward error correction(FEC) has been proposed at the cost of overhead rate. Among the FEC techniques, turbo code, whose performance has been shown to be very close to the Shannon limit, can be classified as a block-based error correction code. In this paper, considering the variable packet size of the multimedia data, we analyzed turbo codes employing the variable-sized interleaver. The effect of the various parameters on the BER performance is analyzed. We show that the turbo codes can be used as efficient error correction codes of multimedia data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.269-276
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• 2016

Internet of Things (IoT) is based on wireless networks being able to connect things and people on a large scale. In the IoT environment, reliable broadcast plays an important role to distribute data to a large number of devices. Energy harvesting from a surrounding environment is a key technique to achieve a sustainable IoT network. In IoT networks, a problem of transmission errors and energy shortage should be mitigated for reliable broadcast. In this paper, we propose an energy-efficient and reliable broadcast method to consider packet errors and energy consumption in the environment where a large number of nodes are connected. The proposed scheme can improve data restoration probability by up to 15% and reduce energy consumption by up to 17%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.600-607
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• 2008

Reliable wireless transmission of data generated by the flight critical subsystems or mission equipments of the unmanned aerial system is critical for mission success. As the UAS system becomes more sophisticated, its dependency on a reliable high rate radio communication system also increases. This requirement is applied not only during the operation phase but also in the early development test phase. This paper introduces a practical cost-effective communication system for a UAS. The downlink module combines analog NTSC video signal with onboard data, and send them using 2.4 GHz carrier wave. The uplink system has less a severe requirement on the bandwidth, and thus uses 430 MHz signal. This paper also presents a sample packet structure which can be adopted for many UAS of similar class.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.1027-1031
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• 2006

Recently, mobile-type analysis system when emergency patient can check his blood condition in the transportation or vessel has being required. Under the present system, it takes lots off-time to know the blood analysis result of patient, so, it may lead to a dangerous situation. But, in this study, analysis time makes to fall down to $1{\sim}min$. to emergency treatment patient more quickly, and you can check the information by wireless PC through Bluetooth base. It is able to measure in about 7minutes from 25minutes of warming-up time in existing facilities by testing temperature peculiarity curve, to operate system without error even minute temperature change by adoption DUAL heating. And Bluetooth base was adopted to reduce power consumption and be able to hospital networking by keeping and sending analyzed data when it needs.

• The KIPS Transactions:PartC
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• v.17C no.2
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• pp.189-196
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• 2010

The LEACH does not use flooding method for data transmission and this makes low power consumption. So performance of the WSN is increased. On the other hand, QoS based algorithm which use restricted flooding method in WSN also achieves low power consuming rate by reducing the number of nodes that are participated in routing path selection. But when the data is delivered to the sink node, the LEACH choose a routing path which has a small hop count. And it leads that the performance of the entire network is worse. In the paper we propose a QoS based energy efficient clustering and routing algorithm in WSN. I classify the type of packet with two classes, based on the energy efficiency that is the most important issue in WSN. We provide the differentiated services according to the different type of packet. Simulation results evaluated by the NS-2 show that proposed algorithm extended the network lifetime 2.47 times at average. And each of the case in the class 1 and class 2 data packet, the throughput is improved 312% and 61% each.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.63-67
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• 2009

In RFID system, Tag's Identification data is processed in host computer by application program. Example of application program is parking administration program, library state program etc.. Tag's ID that is recognized in reader is inputted to the Host computer. Application program of computer searches data in DB of computer such as Tag ID. After finding the same ID, host computer send to control command to driver H/W in accordance with application purpose. But, It need to confirm in long distance whether achievement process is acted normally. There will be the 2 methods, when we monitors the process in long distance. One is wired monitoring system, another is wireless monitoring system. Among wire method, internet communication network is useful. RFID system manufacture first in this treatise. RFID system Embody using EM4095 chip that is doing 125KHz by carrier wave. Tag's characteristic ID is sent in remote place through module that use W3100A chip. This system Manufacture, and data send-receive confirmed using simple application program. Reception confirm by result, and pictures show by whole system and each part. And a control program explained of each part.

• Smart Media Journal
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• v.7 no.4
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• pp.52-60
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• 2018

Energy Management System(EMS) of Microgrid(MG) collects and analyzes data from devices in the microgrid to provide information to operators, users and other systems. In the middle of the process, it is required to securely provide information through both wired and wireless communication networks. In this paper, we design and implement a module that provides encryption and decryption, key management, key distribution, and message authentication functions, thus enabling the development of a system which is safe from the exposure and modulation of data potentially occurrable during data transmission between RTU(Remote Terminal Unit) and EMS. Our method can increase the efficiency of connection and key management for RTU by connecting a virtual device(VD) to RTU.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.231-238
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• 2022

In this paper, among short-range wireless communication technologies such as Beacon, Bluetooth, UWB (Ultra-wideband), ZigBee, NFC (Near Field Communication), Z-Wave, 6LoWPAN (IPv6 over Low power WPAN), D2D (Device to Device), etc., proposed an IoT service platform based on a beacon that can provide indoor positioning. And, a beacon-linked web server was designed by blocking indiscriminate beacon spam signals and applying REST web service technology with flexibility and scalability. Data accessibility between different devices was verified by testing the success rate of data transmission, the success rate of blocking beacon push, the success rate of IoT interlocking processing, the accuracy of location positioning, and the success rate of REST web service-based data processing. Through the designed IoT service platform, various proposals and research on short-distance-based business models and service platforms will be conducted in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.469-471
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• 2021

As wireless communication technology advances to ensure high accuracy and safety at high speeds, research and development of Visible Light Communication (VLC) technology has been accelerated as an alternative to traditional radio frequency (RF) technology. As the radio spectrum of RF communication becomes more congested and demand for bandwidth continues to increase, VLCs that can use unlicensed frequency band are proposed as a solution. However, VLC channels have broadcasting characteristics that make them easily exposed to eavesdropping and jamming attacks, and are vulnerable to MITM (Man-In-The-Middle) due to their line of sight (LOS) propagation characteristics. These attacks on VLC channels compromise the confidentiality, integrity, and availability of communications links and data, resulting in higher data retransmission rates, reducing throughput and increasing power consumption, resulting in lower data transmission efficiency. In this work, we model vulnerable VLC channels to analyze the impact of attacks and communications vulnerabilities by malicious jammers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.502-510
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• 2011

In this research, a wireless movable systems is introduced that is applicable for real-world clinical examination in order to resolve the inconvenience of wired motion analysis system which uses markers by measuring more accurately the angle of the 3D motion. The system is composed of bluetooth data transmission and 6 DOF inertial measurement system that is composed of 3-axis acceleration and 3-axis gyroscope. The samples were collected from 10 feet of 5 young children who were confirmed as patients having flat feet and achilles tendonitis by podiatric expert in pediatrics, and the validity of the system was evaluated by comparison with the opinion by the expert using the EMG data and the data measured by the developed system. ROM of ankle was measured by the difference between the maximum and the minimum peaks of 3-axis values (pitch, roll and yaw) measured at lateral malleolus bone, and based on this measured value, the eversion rate became relatively higher as flat feet state become worse, which is equivalent to the opinion from the podiatric experts. It was shown that there is a relation between the certain muscle activities and the abnormal motion of foot caused by disease.