• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.53-60
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• 2011

In-Home Display (IHD) is one of the most popular ways to induce voluntary customer participation in energy savings. Various communication technologies are used for recent IHD implementations, but most IHD systems are designed for each house because of their limitations such as communication coverage area and operation complexity. In this study, 400MHz RF communication is used for economical large-scale deployment of IHDs especially for apartment complexes that represent typical residentioal environment in Korea. Since it is essential to use internal batteries to increase the usability of IHD, the frequent changes of them should be avoided. By dividing communication data into 3 types such as common data, long term data, and short term data depending on their update periods, energy efficient communication protocol is designed and proposed. In result, the quantity of data and the battery consumption of IHD are reduced to 23.4% and 31.5% each without harming service quality.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.704-711
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• 2003

Recently, the demands for real-time service and multimedia data are rapidly increasing. There are significant redundancies between header fields both within the same packet header and in consecutive packets belonging to the same packet stream. But there are many overheads in using the current UDP/IP protocol. Header compression is considered to enhance the transmission efficiency for small size of payload. By sending the static field information only once initially and by utilizing dependencies and predictability for other fields, the header size can be significantly reduced for most packets. This work describes an implementation for header compression of the headers of U/UDP protocols to reduce overhead on Ethernet network. Typical UDP/IP Header packets can be compressed down to 7 bytes and the header compression system is designed and implemented on the Linux environment. Using the designed Header compression system between a server and a client have the advantage of effective data throughput in network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1510-1516
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• 2011

As emergence of the ubiquitous society, it is possible to access the network for services needed to us in anytime and anywhere. The phenomena has been accelerated by revitalization of the sensor network offering the sensing information and data. Currently, sensor network contributes the convenience for various services such as environment monitoring, health care and home automation. However, sensor network has a weak point compared to traditional network, which is easily exposed to attacker. For this reason, messages communicated over the sensor network, are encrypted with symmetric key and transmitted. A number of symmetric cryptography algorithms have been researched. Among of them HIGHT algorithm in hardware and software implementation are more efficient than tradition AES in terms of speed and chip size. Therefore, it is suitable to resource constrained devices including RFID tag, Sensor node and Smart card. In the paper, we present the optimized software implementation on the ultra-light symmetric cryptography algorithm, HIGHT.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.839-844
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• 2011

IPTV contents are based on MPEG2-TS(Moving Picture Expert Group-2 Transport Stream). The Created content is delivered to each home's Set-Top box through the Internet service network, which will be visible on television through the decoding process. The using and spending of content expanding were quite limited in the other existing lines' devices. For this end, provided methods are to convert MPEG2-TS to other format and then transmit it. These methods are causing not only an overload to the system but also its increasing the hardware resource requirements. In this paper, the MPEG2-TS of IPTV's content using RTP(Real time Transport Protocol) provided by the applicable variety of devices and environmental system, was designed and implemented. Through this paper, the existing MPEG2-TS is providing other devices for distribution and consumption that can give better content to the consumers which means that the QoS(Quality of Service) was enhanced. And, the increased consumption and use of content will help the IPTV business to get more development and activation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2435-2441
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• 2010

A global healthcare system based on M2M technology is proposed to support a good mobility, flexibility and scalability to the patients in 6LoWPAN. Sensor nodes integrated with wearable sensors are linked to gateway with IEEE 802.15.4 protocol and 6LoWPAN protocol for data acquisition and transmission purpose via external network. In the server, heart rate variability signals are obtained by signal processing and used for time and frequency domain performance analysis to evaluate the patient's health status. Our approach for global healthcare system with non-invasive and continuous IP-based communication is managed to process large amount of biomedical signals in the large scale of service range accurately.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.98-99
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• 2007

It is necessary to use satellite radio navigation system as well as satellite radio navigation augmentation system such as differential Global Positioning System to achieve the positioning accuracy and reliability requested by International Maritime Organization in port and coastal area. Especially, position accuracy of DGPS user is effected by accuracy of pseudorange correction broadcasted from DGPS reference station. This paper shows pseudorange correction calculation algorithm adopting a non-common error estimation filter in order to improve accuracy of pseudorange correction. Finally, this paper verifies that the pseudorange correction calculated by adopting a non-common error estimation filter satisfies performance specifications of RTCM.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2183-2190
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• 2013

Container Security Device (ConTracer) which is suggested in this study is to monitor temperature, humidity, and impact inside of the container while the container is transported. ConTracer could also give information to users when a door of the container is opened over 2 inch within 1 second. Additionally, GPS/GLONASS based global position and status information about container are transmitted to a remote server using IoT (Internet of Things) based communication. In this research, we are looking into the development trend of global container security devices; and applying ConTracer to real freight transport from domestic to overseas using Global Roaming Service which is offered for domestic Mobile Communication Companies as well. As a result, we estimate the performance of ConTracer and verify it.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1299-1305
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• 2017

In this paper, we consider a beamforming game between the transmitters in a two-user multiple-input single-output interference channel using limited feedback and investigate how each transmitter is able to find a modified strategy from the quantized channel state information (CSI). In the beamforming game, each of the transmitters (i.e., a player) tries to maximize the achievable rate (i.e., a payoff function) via a proper beamforming strategy. In our case, each transmitter's beamforming strategy is represented by a linear combining factor between the maximum ratio transmission (MRT) and the zero forcing (ZF) beamforming vectors, which is the Pareto optimal achieving strategy. With the quantized CSI, the transmitters' strategies may not be valid because of the quantization errors. We propose a modified solution, which takes into account the effects of the quantization errors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1380-1386
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• 2015

Recently, the importance of users' geographic location information has been highlighted with a rapid increase of online social network services. In this paper, by utilizing geo-tagged tweets that provides high-precision location information of users, we first identify both Twitter users' exact location and the corresponding timestamp when the tweet was sent. Then, we analyze a relationship between the tweet frequency and the average user velocity. Specifically, we introduce a tweet-frequency computing algorithm, and show analysis results by country and by city. As a main result, it is shown that the tweet frequency according to user velocity follows a power-law distribution (i.e., Zipf' distribution or a Pareto distribution). In addition, by performing a comparison between the United States and Japan, one can see that the exponent of the distribution in Japan is smaller than that in the United States.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2885-2891
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• 2015

Twitter, one of online social network services, is one of the most popular micro-blogs, which generates a large number of automated programs, known as tweet bots because of the open structure of Twitter. While these tweet bots are categorized to legitimate bots and malicious bots, it is important to detect tweet bots since malicious bots spread spam and malicious contents to human users. In the conventional work, temporal information was utilized for the classficiation of human and bot. In this paper, by utilizing geo-tagged tweets that provide high-precision location information of users, we first identify both Twitter users' exact location and the corresponding timestamp, and then propose an improved two-stage tweet bot detection algorithm by computing an entropy based on spatio-temporal information. As a main result, the proposed algorithm shows superior bot detection and false alarm probabilities over the conventional result which only uses temporal information.