• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.103-109
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• 2018

One of the 5G goals is provide to high data rates for users moving at high speeds, such as trains. High mobility scenarios such as high speed train (HST) scenarios are expected to be typical scenarios for fifth generation communication systems. As the HST develops rapidly, it is necessary to transmit wireless communication data to train passengers, and the communication speed required by users is gradually increasing. HST users require high network capacity and stable communication services regardless of the location or speed of the HST communication system. Therefore, a transmission frame is constructed for the 5G mobile communication system in the mm band to be used for the fifth generation mobile communication, the HST communication system is implemented, and the performance of the wideband non-stationary MIMO HST channel is analyzed in the HST scenario.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.600-609
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• 2003

A hybrid stabilization approach involving both Passivity Observer/passivity Controller and wave variables is addressed to stabilize the teleoperation system with time delay. To guarantee the stability of master or slave side, Passivity Observer and Passivity Controller are applied. But Passivity Observer and Passivity Controller technique cannot deal with communication delay and even small communication delay cause the system to be unstable. To cope with this problem, wave variables are additionally employed to have robustness to arbitrary delays. To show the validity of our proposed approach, several computer simulation results are illustrated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.147-156
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• 2017

This paper analyzes the performance limit of WAVE system for the platooning service requirements which is referred from the de facto standards. The performance of the packet error rate and mean delay as key parameters in the wireless communication systems should be satisfied to provide safety to the platooning vehicles. The test scenarios are conducted by considering the following vehicle groups: platooning vehicles, vehicles within a hop distance and vehicles within two hop distance( called hidden node vehicles). The models of packet error rate and delay deals with the topology of aforementioned vehicle groups, vehicle speed and communication range. The numerical results are obtained in terms of packet size, packet arrival rate and data transmission rate. Finally, this paper suggests the robust range of packet error rate and delay for the WAVE system to provide the platooning vehicle service.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.245-254
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• 2013

In oriental medicine, it is possible to classify and treat many diseases using the pulse wave detection system. Other problems may arise. As it is a very subjective way to analyze the pulse wave. One problem of the conventional pulse wave detection system is that the arterial pulse sensor is not located correctly at the radial artery. Threrefore measurement results can differ depending on the measurement position and the measurement procedure. This is mostly due to it's sensitivity to high reproducibility. In order to solve this problem this paper proposes an algorithm to analyze the weak pulse wave symptom and strong pulse wave symptom. It uses the portable pulse wave detection system which includes a Hall Sensor. As a final result, it analyzed the weak pulse wave symptom and strong pulse wave symptom by the SPSS statistics technique. It proves that N time (notch point time) and S Amp (rise waveform size) mean values are significantly different in 95% confidence interval.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.7
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• pp.2047-2066
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• 2024

In order to improve the coverage and achieve massive spectrum access, non-orthogonal multiple access (NOMA) technology is applied in millimeter wave massive multiple-input multiple-output (mMIMO) communication network. However, the power assumption of active sensors greatly limits its wide applications. Recently, Intelligent Reconfigurable Surface (IRS) technology has received wide attention due to its ability to reduce power consumption and achieve passive transmission. In this paper, spectral efficiency maximum problem in the millimeter wave mMIMO-NOMA system with IRS is considered. The sparse RF chain antenna structure is designed at the base station based on continuous phase modulation. Furthermore, a joint optimization problem for power allocation, power splitting, analog precoding and IRS reconfigurable matrices are constructed, which aim to achieve the maximum spectral efficiency of the system under the constraints of user's quality of service, minimum energy harvesting and total transmit power. A three-stage iterative algorithm is proposed to solve the above mentioned non-convex optimization problems. We obtain the local optimal solution by fixing some optimization parameters firstly, then introduce the relaxation variables to realize the global optimal solution. Simulation results show that the spectral efficiency of the proposed scheme is superior compared to the conventional system with phase shifter modulation. It is also demonstrated that IRS can effectively assist mmWave communication and improve the system spectral efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.2
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• pp.133-141
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• 2014

Recently, various services are provided by using WAVE protocol for communication among neighboring vehicles. And in order to operate stable system, the gateway for interconnecting in and out vehicle networks is required. In this paper, we propose gateway interconnecting WAVE and CAN protocol. The proposed gateway based on OSEK OS consists of a communication layer, a message translator layer and a message management layer. In the communication layer, WAVE communication part and CAN communication part are designed to communicate with WAVE and CAN. And in the message management layer, message management layer functions to store the received messages and check errors with the message. Based on these functions, experiment was conducted to analyze performance of the gateway with two scenarios such as transmitting periodically BSM as a message structure for safety services in vehicle-to-vehicle communications and responding to road side equipments requiring in-vehicle information. As a result of test, we verify our gateway performance by analyzing measured time in test scenarios.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.13-21
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• 2016

Since the direct-gradient (DG) method uses the Shack-Hartmann wave front sensor (SH-WFS), based on the phase-conjugation principle, for atmospheric compensation in free-space optical (FSO) communication, it cannot effectively correct high-order aberrations. While the stochastic parallel gradient descent (SPGD) can compensate the distorted wave front, it requires more calculations, which is sometimes undesirable for an FSO system. A hybrid compensation (HC) method is proposed by properly using the DG method and SPGD algorithm to improve the performance of FSO communication. Simulations show that this method can well compensate wave-front aberrations and upgrade the coupling efficiency with few computations, preferable correction results, and rapid convergence rate.

• Korean Journal of Materials Research
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• v.29 no.6
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• pp.363-370
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• 2019

The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.943-949
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• 2009

In this paper, the 5.9GHz WAVE(Wireless Access in Vehicular Environments) channel modeling is used by the Jakes channel model for the suitability of the fast wireless channel fluctuation. The performance analysed the fading signal constellation and the spectrum in the IEEE 802.11p spectrum mask, the Doppler effect, the modulation scheme. In addition, the vehicular speed, exactly the performance analysis the WAVE communication systems follow the Doppler effect.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.933-942
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• 2009

In this paper, the WAVE technology for IT based on Intelligent Transport System(ITS) which using by IEEE 802.11a PHY, IEEE 802.11p MAC(Medium Access Control) and IEEE P1609.3 was implemented. The WAVE system was designed that has maximum 0.5km communication range for RSU(Road Side Equipment) between vehicle, 12Mbps transfer speed when downlink at maximum 120km/h vehicle speed. To verify suitableness of the WAVE system for ITS, we measured several parameters on the real road: communication range when low and high speed, link establishment time, data transfer speed, PER (Percent Error Rate), and latency. From the experiment results, we demonstrated that WAVE is a suitable technology for IT based on ITS.