• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.15-21
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• 2002

Re Ministry of Maritime Affairs and Fisheries in Korea completed the installation of 8 maritime DGPS station mfd is to going install 3 additional Maritime DGPS station for the enhancement of dual coverage in Korean coasts until Oct. 2002. Moreover, Korean government decided to provide the NDGPS service over the whole Korean inland area, which will be schedule to complete until June. 2004. On this paper to evaluate the propagation characteristics of using maritime DGPS site as un element of NDGPS ann to evaluate the required number of additional NDGPS sites, the propagation characteristics of the radio waves of 300kHz bands on sea and land nth are studied With the result of study, the conceptional design of Korean NDGPS System is proposed, which consists of 5 NDGPS sites with modified antenna and tかee coverage monitoring sites.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.15 no.3
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• pp.192-199
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• 2015

Heterogeneous cellular networks are gaining momentum in industry and the research community, and are attracting the attention of standard bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are to increase the capacity and coverage of cellular networks. In this article, we provide an overview of expansion strategies, optimal locations of base stations with different characteristics, and radio-planning models.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.101-104
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• 2000

In this paper, we analyze the propagation modeling methods to evaluate the IMT-2000 satellite RTT (Radio Transmission Technology). To generate Rayleigh random numbers having Jake's Doppler power density spectrum, the Rice's sum of sinusoids methods are used and their statistical characteristics are compared with each other.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.125-132
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• 1998

In this paper, radio-wave propagation characteristics for L-band frequency are investigated using real data in case of base station in universal domestic environment. L-band frequency was recently emphasized the importance in PCS network. Measure+ments are carried out on vertical polarization characteristics in the 1.805 GHz frequency, three different estimated models, 3km 300m and 30m, are measured separately for 3 or 4 months at TX/RX fixed states. The experimental results of the estimated models are indicating the difference of 1~6dB compared to the theoretical value. The results present useful data in determining the base station sites.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.314-317
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• 2003

In this paper, a measurement and analysis program is developed, that can be utilized to measure and analyze radio propagation characteristics. This program is able to control the measurement instruments including spectrum analyzer through a GPIB interface, and analyze the measured data to yield mean excess delay and RMS delay spread. The measured path loss can be compared with theoretical path loss in free space or inside tunnels. The measured and analyzed results can also be presented in the forms of graphs. As those tasks can be conducted on the measurement spot, this program is very helpful for performing and verifying measurements.

• Electronics and Telecommunications Trends
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• v.34 no.6
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• pp.28-41
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• 2019

Future mobile services will require data transmission rates of 100 Gbps or higher due to the universalization of virtual and augmented reality devices. Therefore, THz technology, which uses an ultrahigh frequency band of 200 GHz or higher, is expected to be a candidate for such high-quality services. This article describes the current status of THz radio propagation characteristics, device and system developments, and network requirements to identify the overall trends in THz wireless communication technology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1933-1954
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• 2013

Multiple wireless devices are being widely deployed in Intelligent Transportation System (ITS) services on the road to establish end-to-end connection between vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) networks. Vehicular ad hoc networks (VANETs) play an important role in supporting V2V and V2I communications (also called V2X communications) in a variety of urban environments with distinct topological characteristics. In fact, obstacles such as big buildings, moving vehicles, trees, advertisement boards, traffic lights, etc. may block the radio signals in V2X communications. Their impact has been neglected in VANET research. In this paper, we present a realistic and efficient radio propagation model to handle different sizes of static and moving obstacles for V2X communications. In the proposed model, buildings and large moving vehicles are modeled as static and moving obstacles, and taken into account their impact on the packet reception rate, Line-of-sight (LOS) obstruction, and received signal power. We use unsymmetrical city map which has many dead-end roads and open faces. Each dead-end road and open faces are joined to the nearest edge making a polygon to model realistic obstacles. The simulation results of proposed model demonstrates better performance compared to some existing models, that shows proposed model can reflect more realistic simulation environments.

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.7-12
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• 2011

In this study, we investigate on location optimization algorithm of radio-navigation transmitter. The DOP for an each receiver is decided by the location of a transmitter. We provide various results that give an optimum DOP according to propagation characteristics. We use the DTED(Digital Terrain Elevation Data) to improve the accuracy.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.283-288
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• 2013

In this study, we introduce a 3D micro-cell simulator for radio wave propagation analysis in indoor environments. Previous studies treat only the path loss between the transmitter and receiver in 2D geometry. We provide the simulation results of indoor propagation prediction based on various ITU-R Recommendations. Simulation results described here indicate that the low and high frequency bands give quite different characteristics in presented indoor geometry. The propagation loss as a function of distance has two distinct regions. It is similar to that occurring in free space within 5-20m of the transmitter, however, increases significantly as the electromagnetic waves become obstructed by the walls at distances further away in the next region.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.920-926
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• 2012

In this paper, marine accidents recently happened in Korea and Japan for 5 years, especially through the analysis of accident characteristics for fishing vessels, including small vessels were analyzed. Also propose a new maritime safety communication network in the form of a comprehensive considering the wave propagation characteristics and operational characteristics of radio communication equipments should be installed in the vessel through comprehensive analysis of the regulation according to the radio equipment and the ship's location identification device installation and operation.