• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.231-234
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• 2011

Recently, the smart RFID tag technology which can measure external changing environment is globally interesting. In this paper, development of the Smart RFID tag using temperature sensor was represented. Smart RFID tag is basically comprised of antenna which has its bandwidth of 13.56Mhz, temperature sensors and data processing controller. Antenna design and smaller PCB production can be used to agri-food wrap. Since the smart RFID tag is distributed as an attachment to agri-food wrap, consumer can check temperature changes in the distribution process. Because temperature change check in real time, food confirm the status of transportation and the freshness. Also, smart RFID tag can be applied to proposed smart refrigerator.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.3
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• pp.249-255
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• 2002

This paper describes on the extraction of ship's real-time movement information using a combination full-function ARPA radar and ECS system that displays radar images and an electronic chart together on a single PC screen. The radar target extractor(RTX) board, developed by Marine Electronics Corporation of Korea, receives radar video, trigger, antenna bearing pulse and heading pulse signals from a radar unit and processes these signals to extract target information. The target data extracted from each pulse repetition interval in DSPs of RTX that installed in 16 bit ISA slot of a IBM PC compatible computer is formatted into a series of radar target messages. These messages are then transmitted to the host PC and displayed on a single screen. The position data of target in range and azimuth direction are stored and used for determining the center of the distributed target by arithmetic averaging after the detection of the target end. In this system, the electronic chart or radar screens can be displayed separately or simulaneously and in radar mode all information of radar targets can be recorded and replayed In spite of a PC based radar system, all essential information required for safe and efficient navigation of ship can be provided.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.671-677
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• 2013

In this paper, we propose a method of near-field analysis for vehicle LF antennas in order to estimate the accurate reading range of a smart key. The LF antenna consists of a ferrite core and a conducting wire which is coated with polyethylene for insulation, and it is mounted at the rear bumper frame of a commercial vehicle. The reading range of a smart key is measured at nine azimuthal directions distributed around the rear bumper, and then, the received power at each maximum reading range is measured by using a spectrum analyzer. The measurement shows that the maximum reading range exists between 1.38 m and 1.53 m, and the radiated power is between -83.6 dBmW and -75.0 dBmW. We further conducted EM simulation to estimate the reading range and the received power under the same condition that we applied for the measurement. The results demonstrate that an accurate reading range and received power can be achieved by simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1039-1044
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• 2013

We propose a cancellation algorithm based on Alamouti coded OFDM to mitigate ICI due to Frequency Offset (FO) between distributed antennas in the frequency selective fading channel. In the cancellation algorithm, the interference signal is estimated by using the initial detection symbol and then the estimated interference signal is subtracted from the received signal. As the accuracy of initial symbol increases, ICI cancellation becomes more significant. Therefore, the accuracy of the initial detection symbols is very important in the cancellation algorithm. The proposed scheme improves the accuracy of the initial detection symbol by employing an ICI self-cancellation scheme. The proposed cancellation scheme with only one iteration achieves better performance compared to the conventional cancellation schemes with many times iterations based on the conventional Alamouti coded OFDM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.642-647
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• 2007

HAP(High Altitude Platform) systems have been proposed due to their unique advantages over terrestrial and satellite systems as the alternative wireless communication system to deliver the third generation IMT-2000 wireless services. It has been required to study for the power control in W-CDMA HAP system as well as the terrestrial mobile system in order to mitigate interference and increase the capacity. In this paper, a new power control has been proposed for HAP system considering the interference profile into the DB(distributed balancing) SIR(signal to interference ratio)-based algorithm which has been considered in terrestrial system, and estimated by the outage performance of the proposed DB algorithm is better remarkably than DBPA(distance-based power allocation) which is proposed for HAP system, and it is the same regardless of the antenna maximum gain and its sidelobe characteristics.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.50-60
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• 2021

For conventional AESA radars, DC-DC power modules using 300 Vdc have low efficiency, high volume, heavy weight, and high price, which have problems in modularity with T/R module groups. In this paper, to improve these problems, we propose a distributed DC-DC power module with high-voltage 800 Vdc and high-efficiency Step-down Converter. In particular, power requirements for modern and future marine weapons systems and sensors are rapidly evolving into high-energy and high-voltage power systems. The power distribution of the next generation Navy AESA radar antenna is under development with 1000 Vdc. In this paper, the proposed highvoltage, high-efficiency DC-DC power modules increase space(size), weight, power and cooling(SWaP-C) margins, reduce integration costs/risk, and reduce maintenance costs. Reduced system weight and higher reliability are achieved in navy and ground AESA systems. In addition, the proposed architecture will be easier to scale with larger shipboard radars and applicable to other platforms.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.466-471
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• 2015

In this paper, the design technique of the wide swath TOPS(Terrain Observation by Progressive Scan) imaging mode is introduced. The TOPS mode overcomes the scalloping limitations imposed by ScanSAR mode by steering the antenna pattern along track direction during the acquisition of a burst. This paper reports the operation concept of TOPS imaging and mode design result to extract the SAR operational parameters. Finally, several analyzed results such as IRF(Impulse Response Function), NESZ(Noise Equivalent Sigma Zero) and DTAR(Distributed Target Ambiguity Ratio) are presented.

• Journal of Communications and Networks
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• v.5 no.2
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• pp.141-149
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• 2003

In this paper, we investigate design criteria and the performance of the space-frequency bit-interleaved coded modulation (SF-BICM) systems in frequency-selective Rayleigh fading channels. To determine the key parameters that affect the performance of SF-BICM, we derive the pairwise error probability (PEP) in terms of the determinant of the matrix corresponding to any two codewords. We prove that the bit-interleavers do the function of distributing the nonzero bits uniformly such that two or more nonzero bits are seldom distributed into the symbols that are transmitted in the same frequency bin. This implies that the bit-interleavers transform an SF-BICM system into an equivalent 1-antenna system. Based on this, we present design criteria of SFBICM systems that maximizes the diversity order and the coding gain. Then, we analyze the performance of SF-BICM for the case of 2-transmit antennas and 2-multipaths by deriving a frame error rate (FER) bound. The derived bound is accurate and requires only the distance spectrum of the constituent codes of SF-BICM. Numerical results reveal that the bound is tight enough to estimate the performance of SF-BICM very accurately.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.212-220
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• 2014

The current cellular communications are optimized for low mobility users, meaning that their performance is degraded at high speed. Therefore, passengers in a high-speed train experience very poor radio link quality due to the significantly large number of simultaneous handovers. In addition, wireless data traffic is expanding exponentially in trains, subways and buses due to the widespread use of smartphones and mobile devices. To solve the inherent problem of cellular communication networks and meet the growing traffic demand, this paper proposes the mobile hotspot network of a millimeter-wave communication system as a mobile wireless backhaul. This paper describes the physical layer design of uplink and downlink in the proposed system, and the performances of uplink and downlink are evaluated under Rician fading channel conditions. The implemented baseband prototype of the proposed millimeter-wave communication modem is presented. This system can provide a Gbps data rate service in high-speed trains carrying hundreds of wireless Internet users.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.94-94
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• 2010

As a new plasma source for the plasma enhanced chemical vapor deposition (PCVD) of ${\mu}c$-Si deposition, we have demonstrated a microwave-excited plasma source, which can produce high density (${\sim}10^{12}\;cm^{-3}$) plasma with low electron temperature (~1 eV) and low plasma potential (~10 V). In this plasma source, microwave power radiated from slot antenna is distributed along the plasma-dielectric interface in large area and this enables us to produce uniform high-density plasma in large area. To optimize deposition conditions, deep understanding of gas phase chemistry is indispensable. In this presentation, we will discuss on the gas phase diagnostics of microwave $SiH_4/H_2$ plasma such as $SiH_4$ dissociation or $SiH_3$ radical profile as well as deposited film properties.