• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1248-1256
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• 2015

It is necessary to apply an exact data and a precise prediction model for a rain attenuation to design the link margin for a data link using Ku-band with the serious effect by rain. In this paper, we investigate the regional rainfall-rate distribution of Korea proposed in TTAK.KO-06.0122/R1 and compare it with the distribution provided by Rec. ITU-R PN.837-1 and Crane. And, the rain rate climate regions similar with the rainfall-rate distribution of Korea in Rec. ITU-R PN.837-1 and Crane model are selected. Finally, using Rec. ITU-R P.618-8 and Crane rain attenuation prediction model, we derive and analyze the rain attenuation for Ku-band frequency according to the time percentage of an average year and the distance of wireless communication link between unmanned aerial vehicle (UAV) and ground data terminal (GDT).

• Electronics and Telecommunications Trends
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• v.32 no.4
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• pp.78-88
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• 2017

무인기의 기술 발전에 따른 운송, 통신중계, 교통감시, 산불감시 진화, 재해 재난대처 등 무인기의 민간 및 공공 수요가 확대되고 있다. 무인기는 국가 공역으로의 운항이 요구되는데, 국가 공역으로의 안전한 진입을 위해서는 유인항공기 조종사에 의한 시각 감지 및 회피와 동일할 수준의 안전성을 제공하는 탐지 회피 능력과 함께 신뢰성 높은 무인기 제어용 통신링크 확보가 필수적으로 요구되고 있다. 따라서, 본고에서는 국외 기술 개발 및 표준화 동향을 바탕으로 국가 공역에서의 무인기의 안정적 진입을 위해 필요한 무인기 지상 제어용 통신 및 네트워크 기술에 대해 살펴보고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.454-460
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• 2012

DTC(Data Terminal Controller) for UAV has been developed using FPGA. It provides the functions of Error Correction and Time-division Mux/Demux for stable data-link. RTOS VxWorks also has been used for real-time control of data-link. FPGA Design of DTC facilitates the modification and extension of various I/O device, and VxWorks ensures real-time availability of data-link control and provides flexibilities of changes of S/W design. The DTC is expected to be deployed easily for various UAV systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.965-976
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• 2012

Multi-Platform Image and Intelligence Common data link(MPI-CDL) systems are designed to transmit the imaginary and signal intelligence data at an aeronautical to ground line of sight(LOS) link. This paper proposes a method to predict a link availability and analyzes the required link margin to satisfy a given link availability for MPI-CDL systems. To estimate a link availability the proposed method applies the conditional probability so that both a rain attenuation and a multipath fading are considered simultaneously. Link margins to meet the link availability for MPI-CDL systems are calculated according to an operating environment including frequencies, flight altitudes and transmission ranges. The required link margins for actual unmanned air vehicle systems are also given by simulation results.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.21-30
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• 2020

In this paper, we predicted the propagation loss for the air-to-ground (A2G) channel between the ground control system and the unmanned aerial vehicle (UAV) using the prediction model for the aircraft recommended by the International Telecommunication Union (ITU). We analyzed the network coverage of the aerial relay system based on the medium altitude UAVs by expanding it into the air-to-air (A2A) channel. Climate and geographic factors in Korea were used to predict propagation loss due to atmospheres. We used the measured data published by the Telecommunication Technology Association (TTA) for regional rainfall-rate and effective earth radius factors to increase accuracy. In addition, the aerial relay communication system used the key parameter of the common data link (CDL) system developed in Korea recently. Prediction results show that the network coverage of the aerial relay system broadens at higher altitude.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2541-2546
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• 2013

In this paper, we proposed on the azimuth correction method for a line-of-sight data-link tracking antenna system. Tracking antenna system is essential to maintain line-of-sight between moving object and data-link equipment. In order to calculate the azimuth and elevation between the moving object and antenna system, we used GPS data. also to match the each coordinate systems, we used geomagnetic sensor or beacon. However, the geomagnetic disturbance-prone terrain in places difficult to correct calibration. The first step, finds the location of the strongest RF signal, we should remember the difference between the reference point and the detected position of the antenna. The second step, we could communicate each other. And the azimuth angle is calculated by GPS values. Despite the geomagnetic interference, we can correct the azimuth angle quickly and easily.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.329-335
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• 2016

Unmanned aircraft systems (UAS) are defined as the system whose components include the necessary equipment, network, and personnel to control an unmanned aircraft. In the past, UAS were predominately operated for military operations. However, nowadays, the applications of UAS to commercial area are explosively augmented and UAS are being expected to be integrated in national airspace. Therefore, the need for the standardized datalink systems rapidly and the development of control and non-payload communication (CNPC) system are being processed for integration in national airspace in United States and Europe. In this paper, the technology trends for UAS CNPC datalink are explained and presented the performance evaluation results for CNPC system, which is the modified version of IEEE 802.15.4 ZigBee system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.982-989
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• 2013

Omni-directional antennas of UHF-Band are located on the top and bottom side of the Smart UAV in order to connect a link always. Therefore one of each antennas should be connected to a ground antenna. Because the communication link of the omni-directional antennas is influenced by the objectives around aircraft, the clearance of LOS(Line of Sight) should be achieved in order to avoid a loss of link. In this paper, the analysis results on the influence of the complex objectives placed around the antenna on the communication link are presented according to the change of attitude angles. The best positions of antennas are selected based on the electromagnetic analysis using XGTD tool which supports the modeling of antenna pattern. The flight tests of the Smart UAV were successfully performed with the selected antenna position.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1C
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• pp.89-96
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• 2012

Since tactical robots are going to be grown and tactical data communications will be more network-centric, the reliability of wireless tactical data networks is going to be very important in the future. However, the connectivity of such wireless tactical data networks can be extremely uncertain in practical circumstances. In this paper, we propose a searching technique to find out the weak boundary area of the network connectivity using a small UAV(unmanned aerial vehicle) which has a simple polling access function to wireless nodes on the ground in wireless tactical data networks. The UA V calculates the network topology of the wireless tactical data networks and coverts it to the Lapalcian matrix. In the proposed algorithm, we iteratively search the eigenvalues and find a minimum cut in the network resulting in finding the weak boundary of the connectivity for the wireless tactical data networks. If a UAV works as a relay nodes for the weak area, we evaluate that the throughput performance of the proposed algorithm outperforms star connection method and MST(minimum Spanning Tree) connection method. The proposed algorithm can be applied for recovering the connectivity of wireless tactical data networks.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.540-547
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• 2015

This paper describes development contents and flight tests of an ACMI simulator based on LVC integrating architecture. ACMI is the system that provides air combat training and ground bombing training for improving fighting efficiency, that is the live simulation involving real people to operate real systems. ACMI simulator was developed for technic acquisition of LVC interoperability by using data link communication. ACMI simulator simulated maneuvering of a fighter by operating an UAV, a fighter can be distinguished from an UAV by maneuvering characteristics. This study proposes maneuvering simulation method by using flight data of the UAV, and performed its flight test for verifying similarity of fighter maneuvering.