• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.866-873
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• 2006

In this paper, we proposed and fabricated the single-feed dual-band circular patch antenna for S-DMB(Satellite-Digital Multimedia Broadcasting) and ITS(Intelligent Transport Systems) services. The manufactured dual-band antenna showed that the measured -10 dB bandwidth and the minimum return loss was 90 MHz and -35 dB for S-DMB, 180 MHz and -18 dB for ITS, respectively. It is noticed that the measured and the simulated results are agreed well. And the antenna gain of S-DMB and ITS has 2.3 dBi and 2.7 dBi, respectively.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.507-513
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• 2018

The maritime autonomous surface ship is automatically collects and manages various information necessary for the operation to minimize human intervention and safely perform the mission assigned to the ship. And the ship may autonomously operate the partial or entire route to the destination determined by the ship himself. This ship navigation technology allows partially remote control the ship to be operated if necessary. The maritime autonomous surface ship (MASS) should collect and manage signals of various navigation communication equipments and engines mounted on the ship for safe operation. This requires a common platform technology. In this paper, we propose a common platform that is the core of smart ship implementation. Territorial authorities and ships are connected by satellite or terrestrial communication. In such a communication environment, information is exchanged smoothly in real time. This allows the onshore authorities to monitor ships and provide remote control to enable safe vessel navigation at sea.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.2
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• pp.68-75
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• 2009

Up to date, demands for satellite including communication are increasing. Advanced countries on space technology such as America, Russia, Europe, Japan, China and so on already had secured launch vehicle technology which can insert a large class satellite to proper orbit. The introduction of technologies on the large class launch vehicle including propulsion system is difficult due to the utilization possibility for defensive reason. The acquisition of indigenous technical expertise on the design and manufacture of valves is believed to contribute to the successful local development of valves for propulsion systems and to significant improvement of local technical level of valve design and development. This paper introduces current status of valves developed by other countries as well as valves developed in domestic. The Developed technology of valves may underlie the construction of engine control systems required for the reliable operation of the KSLV-II engine system and propulsion system.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.162-165
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• 2017

In an effort to compensate the rising of the data throughput demand nowadays, there have been many research works to optimize the radio resource and increase the capacity of the network. At the present, small cell network, mmWave band and beamforming technology are leading the trend and becoming the core solutions of the fifth generation (5G) cellular networks. Since the propagation characteristics of radio wave in the mmWave band is quite different from the conventional bands, the communication systems which work in these bands have to be redesigned. In this paper, a 3D simulation model is discussed for cellular network at 60 GHz in outdoor environments. Coverage analysis and system performance is carried out for a small cell system in the typical urban environment including street canyon simulation scenario. In addition, the beamforming technique is considered to evaluate the throughput improvement. Simulation results show that the mmWave small cell systems is expected to be one of the major candidate technologies to satisfy the requirements of 5G in terms of data rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.393-400
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• 2014

In this paper, we have designed the transmitter for earth station terminal operating with military geostationary satellite on Ka-band that is complied with MIL-STD-188-164A. The designed antenna of this terminal is dual-offset gregorian reflector which is consist of corrugated horn and iris polarizer, othermode transducer. This antenna meets radiation pattern and transmit EIRP spectral density requirements in this standard. The designed RF systems of this terminal are consist of Block Up Converter(BUC) converting frequency band from IF to Ka band and SSPA having low-power consumption and compact light-weight using the pHEMT MMIC compound devices. This RF systems applied with VSWR, spurious/harmonic suppression, output flatness and phase noise requirement in this standard.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1959-1964
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• 2015

This research was focused on the analysis of navigation parameters from the received L1, C/A signal of the recent GPS, which has advanced with the SA policy change and the GPS modernization policy by the United States. It was done as a first step study for a comprehensive analysis on the multiple satellite navigation systems which will be adding or separating GPS signal. In particular, the statistical analysis on the GDOP change and positional accuracy based on the geocentric and spherical coordinate systems were investigated with carrier- to-noise ratio and the satellite geometry, The obtained GDOP values of HDOP, PDOP, VDOP are 0.5, 1.2, and 1.1, respectively in deviation. In addition, the positioning accuracies with these GDOP values were analyzed in the ellipsoidal and ECEF coordinates.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.226-234
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• 2024

The frequent handover problem and playing ping-pong effects in 5G (5th Generation) ultra-dense networking cannot be effectively resolved by the conventional handover decision methods, which rely on the handover thresholds and measurement reports. For instance, millimetre-wave LANs, broadband remote association techniques, and 5G/6G organizations are instances of group of people yet to come frameworks that request greater security, lower idleness, and dependable principles and correspondence limit. One of the critical parts of 5G and 6G innovation is believed to be successful blockage the board. With further developed help quality, it empowers administrator to run many systems administration recreations on a solitary association. To guarantee load adjusting, forestall network cut disappointment, and give substitute cuts in case of blockage or cut frustration, a modern pursuing choices framework to deal with showing up network information is require. Our goal is to balance the strain on BSs while optimizing the value of the information that is transferred from satellites to BSs. Nevertheless, due to their irregular flight characteristic, some satellites frequently cannot establish a connection with Base Stations (BSs), which further complicates the joint satellite-BS connection and channel allocation. SF redistribution techniques based on Deep Reinforcement Learning (DRL) have been devised, taking into account the randomness of the data received by the terminal. In order to predict the best capacity improvements in the wireless instruments of 5G and 6G IoT networks, a hybrid algorithm for deep learning is being used in this study. To control the level of congestion within a 5G/6G network, the suggested approach is put into effect to a training set. With 0.933 accuracy and 0.067 miss rate, the suggested method produced encouraging results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.350-356
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• 2014

In this paper, we design a local signal to improve a tracking performance of time-multiplexed binary offset carrier (TMBOC) signal, which was adopted in modernized global positioning systems (GPS). Specifically, considering that TMBOC signal includes BOC(6,1) components, we first obtain local signal by evenly dividing sub-carrier of TMBOC(6,1,4/33) by the period of a BOC(6,1) pulse. Finally, we remove side-peaks of TMBOC(6,1,4.33) autocorrelation via combination of partial correlations given from designed local signal and solve the ambiguity problem. From numerical results, when performing signal tracking using the designed local signal, we demonstrate that the improved tracking error standard deviation (TESD) performance is offered as compared its autocorrelation and the conventional correlation functions.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.134-141
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• 2020

Telemetry system is a communication system that measures and transmits various signals in the aircraft to the ground for collecting and monitoring flight data during the development of unmanned air vehicle and satellite launch vehicles. With the recent development of wireless communication technology, it is becoming important to apply encryption of telemetry system to prepare with security threats that may occur during flight data transmission. In this paper, we suggested and implemented the application method of ARIA-256, Korean standard encryption algorithm, to apply encryption to telemetry system. In consideration of the block error propagation and the telemetry frame characteristics, frame is encrypted using the CTR mode and can apply the Reed-solomon codes recommended by CCSDS. ARIA algorithm and cipher frame are implemented in FPGA, and simulation and hardware verification system confirmed continuous frames encryption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1620-1625
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• 2004

To advance fisheries, we set developmental directions of fishery information by grasping present situations and analyzing maritime & fisheries issues. We promote various policies through effective systematical information data bases, based on both control and utilization of oceanic resources. For these puposes, it is imperative that we set up fisheries communication networks. There are satellite assisted informational networks to assist fishing vessels with their marine based movements. However, there's no hope for poorly equipped fishermen to adopt this network because of extravagant network call charges. So we think that using existing SSB communication system is the best plan. We organize fishery communication network by HF SSB communication which doesn't have operational costs. We build wireless transmitting and receiving stations that are basic systems of informnation, and equip wireless data communication systems by the use of wireless communication network protocols in coastal stations. It is necessary that a fish boat has a terminal device for wireless data communication. In this research we can conclude that if we transmit the location of a fishing boat in-real time through GPS channels then we propose that some methods be formulated to able terminal devices on fishing boats to collect various types of information, such as meteorological and oceanic conditions.