• Journal of Navigation and Port Research
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• v.35 no.6
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• pp.463-467
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• 2011

As the increasing of requirement for safety navigation, IMO has enforced the mandatory installation of vessel AIS equipment by SOLAS regulation. The AIS transceiver broadcasts various vessel information which can be gathered by the receivers on-board or on-shore. And, recently, as web-based application developments on various devices have been increased, there are more and more requirements of AIS information presentation on internet. To meet these web-based application requirements, this paper shows the practical implementation of the AIS display system, which is on the Google maps as online commercial map and adopts the HTML5 as a web standard.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3862-3888
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• 2017

In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2140-2145
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• 2008

We design and synthesize a 128-point FFT processor for multi-band OFDM, which can be applied to a UWB transceiver. The structure of a 128-point FFT processor is based on a Radix-2 FFT algorithm and a R2SDF pipeline architecture. The algorithm is efficiently modeled in VHDL and the result is simulated using Modelsim. Finally, they are synthesized on Xilinx Vertex-II FPGA, and an operational frequency of 18.7MHz has been obtained. It is expected that the proposed 128-point FFT processor can be applied to an entire FFT block as one of parallel processed FFTs. In order to obtain the enhanced maximum frequency of operation, we design the FFT module consisting of four 128-point FFT processors for parallel process. As a result, we achieve the performance requirement of computing the FFT module in multi-band OFDM symbol timing in 90nm ASIC process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.1038-1041
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• 2009

Wireless sensor network with wireless sensor nodes which equipped with temperature, humidity, illumination, or soil sensor etc, get a natural environment information and analyze and utilized variety way.these network consist of a short distance wireless communication and multi-hop techniques with multiple nodes equipped low-power wireless transceivers. so the characteristic of the data collected through the wireless sensor network is obtained from compact nodes within a limited range. However, to get a data from the wireless sensor nodes scattered in a wide range, this network needs a wireless transceiver that consumes many power or a lot of intermediate nodes. then, merit of low cost and low electrical energy decrease. To solve this problem, this paper offers environment monitoring system using autonomous mobile robot that collect data from groups of each sensor networks scattered widely.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.579-593
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• 2010

Low-power radio frequency (RF) chip transceiver technology and the associated structural health monitoring platforms have matured recently to enable high-rate, lossless transmission of measurement data across large-scale sensor networks. The intrinsic value of these advanced capabilities is the allowance for high-quality, rapid operational modal analysis of in-service structures using distributed accelerometers to experimentally characterize the dynamic response. From the analysis afforded through these dynamic data sets, structural identification techniques can then be utilized to develop a well calibrated finite element (FE) model of the structure for baseline development, extended analytical structural evaluation, and load response assessment. This paper presents a case study in which operational modal analysis is performed on a three-span prestressed reinforced concrete bridge using a wireless sensor network. The low-power wireless platform deployed supported a high-rate, lossless transmission protocol enabling real-time remote acquisition of the vibration response as recorded by twenty-nine accelerometers at a 256 Sps sampling rate. Several instrumentation layouts were utilized to assess the global multi-span response using a stationary sensor array as well as the spatially refined response of a single span using roving sensors and reference-based techniques. Subsequent structural identification using FE modeling and iterative updating through comparison with the experimental analysis is then documented to demonstrate the inherent value in dynamic response measurement across structural systems using high-rate wireless sensor networks.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.370-381
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• 2021

This paper presented an efficient transceiver structure of multiband Frequency Shift Keying (FSK) signals with direct sequence spread spectrum for maintaining covertness and performance. In aspect to covertness, direct sequence spread spectrum method, which multiplying by Pseudo Noise (PN) codes whose rate is much higher than that of data sequence, is employed. In aspect to performance, in order to overcome performance degradation caused by multipath and Doppler spreading, we applied multiband, turbo equalization, and weighting algorithm are applied. Based on the simulation results, by applying 4 number of multiband and number of chips are 8 and 32, experiments were conducted in a lake with a distance of moving from 300 m to 500 m between the transceivers. we confirmed that the performance was improved as the number of bands and chips are increased. Furthermore, the performance of multiband was improved when the proposed weighting algorithm was applied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.857-867
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• 2018

Active array radar is evolving into digital active array radar. Digital active array radar has many advantages for making several simultaneous radar beams from the digital receive data of each element. A digital-type transceiver(TR) module is suitable for this goal in radar. In this work, the design results of an L-band digital TR module are presented to verify the possibility of fabrication for a digital active array antenna. This L-band digital TR module consists of a gallium-nitride-type HPA to achieve a more than 350-W peak output power and one-chip transceivers that include a digital waveform generator and analog digital converter. The receiving gain was 47 dB, the noise figure was less than 2 dB, and the final output type of the four channel receiving paths was one optic signal.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.6
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• pp.59-66
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• 2018

In this paper, we experimented how long distance voice communication is possible After implemented PTT(Push to talk) Bi-directional radio using open source project Codec 2, which is a low speed voice codec for digital amateur radio and 900MHz FSK transceiver. In case of a general digital radio, the AMBE+2 codec, which is regarded as an industry standard in terms of performance, is expensive and has the monopoly of technology. Using the 400MHz band in terms of frequency, narrow bandwidth of DMR(12.5kHz) and DPMR(6.25kHz) is used, so the data rate is low. In the 900MHz bandwidth can be extended, which is advantageous in terms of data transmission. As a result of the voice quality and distance field test, we could find that the communication takes place within about 500m. In this paper, only voice communication is reviewed. if a review of data transmission such as a simple image is added, this solution can be used in various fields as a low cost IOT radio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.518-521
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• 2019

In this paper, an active antenna module operating in the 60 GHz band is designed and fabricated by combining a commercial transmitter chip and patch array antenna. The designed module is composed of an antenna PCB and a PCB with a transmitter chip. The frequency-control and bias-control signals are applied to the transmitter chip, using an Arduino kit. A baseband I/Q signal is also applied to the chip. A ring hybrid balun converts the output of the transmitter module to a single output, which is the output of the transmitter chip that outputs a differential output. The output is delivered to the $2{\times}4$ microstrip patch array antenna PCB as a micro-computer connector. The radiation pattern of the millimeter-wave signal of the final output is compared with the simulation results. The measured radiation patterns of the fabricated active antenna module confirm that the positions of the 3 dB beam width and null point agree well with the simulation results.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.321-326
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• 2021

Wireless communication is a core technology constituting the Internet of Things (IoT), but there is no suitable educational equipment to learn various wireless communication technologies used in the Internet of Things through practice. This paper deals with the development of advanced education and training equipment that can perform various IoT wireless communication practices. It uses an Arduino mega board as a device to control various sensors. As wireless network technologies to send and receive the sensing date wirelessly, it makes use of RFID/NFC and Bluetooth among WPAN technologies, WiFi among WLAN technologies and LoRa and 2.4GHz wireless transceiver among WWAN technologies. In addition, GPS, infrared communication, I2C communication, and SPI communication are organized so that various IoT wireless communication technologies can be learned through practice. In addition, since the educational equipment developed in this paper is equipped with two devices, it is designed to perform transmission and reception experiments for wireless network technology within the equipment.