• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1668-1675
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• 1999

In this thesis, a narrowband bandpass filter using HTS is proposed for the multiplexer of the satellite communication subsystems. The proposed structure using HTS provides the narrower band and the lower insertion loss characteristics than the conventional parallel-coupled-line bandpass filter. The filter structure using hairpin-line only cause the spurious modes due to the surface waves. But these modes can be lessened by using the hybrid hairpin-line/parallel-coupled-line proposed in this thesis. The narrowband bandpass filters using HTS at the operation frequency of 14.25 GHz are fabricated to have the narrow bandwidth less 1% and the insertion loss less 3dB in comparison with the normal metal microstrip filter with the same three poles. The experimental results show that the filter using HTS has the characteristics of the narrower bandwidth and less insertion loss and can be fabricated with more compact size in comparison with the bandpass filter using normal metal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.4
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• pp.572-584
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• 1993

In this paper, we propose an efficient method to allocate carrier frequencies so as to minimize intermodulation products in two-level SCPC systems in which Hub station and many Remote stations communicate each other through the satellite transponder. Also we present a very efficient method to evaluate intermodulation products with highly reduced CPU time in two-level SCPC systems. We study and analyze the performance of some possible methods to extend the Deletion and Insertion operation, which is proposed by Okinaka and applied to only one-level SCPC systems, to two-level SCPC systems. The proposed algorithm is carefully selected out of these methods and is optimized, which shows superior performance to any other published strategies, especially in that it has very excellent characteristics in terms of generality for practical application. Considering the fact that most published strategies are seldom applicable to actual two-level SCPC systems, we can say that the proposed algorithm in this paper is quite meaningful.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.924-933
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• 2008

This paper proposes a novel LDPC code decoder architecture to improve throughput for DVB-S2, a second generation standard of ETSI for satellite broad-band applications. The proposed architecture clusters 360 bitnodes and checknodes into groups utilizing the property of IRA-LDPC code. Functional modules which perform calculations for bitnode groups and checknode groups have local memories and store the messages from the other type of functional modules connected by edges at their local memories. The proposed architecture can avoid memory conflicts by accessing stored messages sequentially, hence, increases throughput in the proposed DVB-S2 LDPC code decoder architecture. The proposed architecture was synthesized using the TSMC 90nm technology. Synthesis results show that throughput of the proposed architecture is improved by 104% and 478%, respectively, when compared with those of the architectures proposed by F. Kienle and J. Dielissen.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.552-557
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• 2017

Wire, wireless digital broadcasting has sharply expanded with the birth of high definition TV since 2010, the use of duplex contents as well as simplex contents has rapidly increased. Currently, our satellite communications system adopted DVB by European digital broadcasting standardization organization as a standard of domestic data broadcasting, the method how to use selective contents has been studied variously according to the development of IPTV. Digital broadcasting utilizes the method using Transport Stream Packet(TSP) by the way of multiplexing of information in order to send multimedia information such as video, audio and data of MPEG-2, this streams include detail information on TV guide and program as well as video and audio information. In order to understand these data broadcasting system, this study realized TS analyzer that divides transport stream (TS) by packet in Linux environment, analyzes and prints by function, it can help the understanding of TS, the enhancement of stream parsing ability.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1433-1435
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• 2003

Very decisive progress was made in advancing fundamental POL-IN-SAR theory and algorithm development during the past decade. This was accomplished with the aid of airborne & shuttle platforms supporting single -to-multi-band multi-modal POL-SAR and also some POL-IN-SAR sensor systems, which will be compared and assessed with the aim of establishing the hitherto not completed but required missions such as tomographic and holographic imaging. Because the operation of airborne test-beds is extremely expensive, aircraft platforms are not suited for routine monitoring missions which is better accomplished with the use drones or UAVs. Such unmanned aerial vehicles were developed for defense applications, however lacking the sophistic ation of implementing advanced forefront POL-IN-SAR technology. This shortcoming will be thoroughly scrutinized resulting in the finding that we do now need to develop most rapidly POL-IN-SAR drone-platform technology especially for environmental stress-change monitoring with a great variance of applications beginning with flood, bush/forest-fire to tectonic-stress (earth-quake to volcanic eruptions) for real-short-time hazard mitigation. However, for routine global monitoring purposes of the terrestrial covers neither airborne sensor implementation - aircraft and/or drones - are sufficient; and there -fore multi-modal and multi-band space-borne POL-IN-SAR space-shuttle and satellite sensor technology needs to be further advanced at a much more rapid phase. The existing ENVISAT with the forthcoming ALOSPALSAR, RADARSAT-2, and the TERRASAT will be compared, demonstrating that at this phase of development the fully polarimetric and polarimetric-interferometric modes of operation must be viewed and treated as preliminary algorithm verification support modes and at this phase of development are still not to be viewed as routine modes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10C
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• pp.984-994
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• 2003

This paper proposes a novel blind adaptive algorithm for computing the weight vector of an antenna array system. The new technique utilizes a Generalized On-Off algorithm to obtain the weight vector maximizing the SINR(Signal to Interference plus Noise Ratio) of the received signal. It is observed that the proposed algorithm generates a suboptimal weight vector with a linear computational load(O(6N+8)). From the various simulations, it is confirmed that, when the signal environment becomes adverse, e.g., low Processing Gain, and/or wide angular spread. the proposed algorithm outperforms the conventional one in terms of the communication capacity by about 3 times. Applying the proposed algorithm to satellite tracking systems as well as IS2000 1X mobile communication system, we have found that both communication capacity and communication quality are significantly improved.

• 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.

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.105-114
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• 2021

ESICD(Electrical Signal Interface Control Document) refers to a document that describes protocols and data for communication between components consist of a system. Each component developer gathers at a specific place to conduct an integrated test for ESICD verification. In this case, it often happens that the integration test is delayed due to a simple mistake of software developers. There are two reasons for this situation: First, software developers do not perform sufficient verification because it is difficult to configure the system environment in a Lab, and second, they do not immediately find the cause of errors occurred during integration tests. Therefore, in this paper, we propose a strategy to effectively perform ESICD verification, which takes a lot of time between the production and implementation stage of the weapon system development stage and the system integration test stage.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.308-315
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• 2023

Russia invaded Ukraine in February 2022. Many military experts predicted that Russia could defeat Ukraine within a week, but the Ukraine-Russia War has not been going as expected. Indeed, Ukraine military has been defending well and seems to fight more efficiently than Russian military. There are many reasons for this unexpected situation and one apparent thing is due to artificial intelligence (AI) technologies. This study focused on AI-enabled combats that the Armed Forces of Ukraine has carried out around Siverskyi Donets River, the Crimean Peninsula, and suburbs of Kyiv. For more systematic analysis, the revolution in military affairs (RMA) theory was applied. There are four significant implications inferred by studying current Ukraine-Russia War. First, AI technologies are effective even in the current status and seems to be more influential. Second, hyper-connected network by satellite communications must be needed to enhance the AI weapon effects. Third, military AI technologies should be based on the civil-military cooperation to keep up with pace of technological innovation. Fourth, AI ethics in military should be seriously considered and established in the use of AI technologies. We expect that this study could help ROK Armed Forces to be modernized in the revolutionary fashion, especially for manned and unmanned teaming (MUM-T) system.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.58-66
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• 2023

The latest global issues are the Space economy and low-orbit Space communication. 3GPP announced Release 17 standardization in June 2022, and in this regard, the United States prepared a strategy to enhance the competitiveness of the low-orbit 5G-NTN Space industry, and create an ecosystem at the national level in March 2023. Global smartphone semiconductor manufacturers have announced the development and verification results of standard-based chip technology, and satellite communication operators are launching low-orbit 5G-NTN Space communication services and rate products through convergence between terrestrial communication networks. This study diagnoses the current status of Korea's low-orbit 5G-NTN space communication ecosystem. We present our ecosystem creation strategy in terms of fair competition in the market, the service legal system, and the national R&D governance system.