• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.530-538
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• 2011

In this paper, the feasibility of LEO(low earth orbit) satellite-based automatic identification system (SAT-AIS) for the coastal area of the South Korea is evaluated in the context of ship AIS transmission detection probability. We evaluate and compare AIS signal detection probability of ORBCOMM satellites and LEO-one satellites considering link budget, SOTDMA protocol and satellite's swath width. The simulation determines the total number of vessels served by those satellites according to satellite's swath width and thus, By simulation results, the ORBCOMM SAT-AIS system outperforms LEO-one SAT-AIS system. The suggested ORBCOMM based SAT-AIS system can be a solution to resolve the existing limited transmission distance problem of the conventional ship-to-shore AIS system.

• Spatial Information Research
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• v.18 no.3
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• pp.85-94
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• 2010

This study presented a method to allocate RFID reader sites for the weekly no driving day program. In resent years, three metropolitan cities begin to operate the system to resolve the traffic jam, air pollution, and oil cost, which is expected to be operated across the country in a few years. In this regard, the accurate verification of the observance of the cars which are participated in the system is needed so that the more benefits are rewarded to observing participants but not violating ones. Thus, this study distinguished road sections where the system of the Daegu metropolitan city cannot determine the observance of the participated cars when the cars detour the RFID readers by employing a set of data from the traffic census, digital maps, and terrestrial photographs of the superstructures on the roads. Then, the appropriate sites for additional RFID readers were determined based on those sections in the road network and the types of the road superstructures.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.337-344
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• 2008

Underwater acoustic sensor networks exhibit characteristics such as high propagation delay and low data rates, which are different from those of terrestrial wireless networks. Therefore, the conventional protocols used in wireless networks can be restrictive and inefficient when applied to underwater acoustic sensor networks. In this paper, we propose a medium access control protocol (MAC) to enhance the energy efficiency and throughput in underwater acoustic sensor networks. The proposed protocol employs a slot-based competition mechanism that reserves a time slot to send a data packet in advance. In the proposed protocol, collision between nodes can occur due to competition to obtain a slot. However, the proposed protocol minimizes the collisions between nodes because the nodes store the reservation information of the neighboring nodes, this reduces unnecessary energy consumption and increases throughput. We perform a simulation to evaluate the performance of the proposed protocol with regard to the energy consumption, the number of collision, channel utilization, throughput and transmission delay. We compare the proposed protocol with the conventional protocol, and the performance results show that the proposed protocol outperforms the conventional protocol.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.172-180
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• 2014

The purpose of this study is to examine how the Munjeonsa(SPC) has influenced the way terrestrial broadcasting networks produce drama. The study has three research objectives. First, this study investigates why the networks use SPC for drama production. Second, the study examines the features in the process of the setup and operation of SPC. Third, the study identifies the impacts of SPC on networks' drama production. This study analyzes which was produced by KBS SPC. The results of this study are as follows. First, networks introduce SPC to procure an enormous production costs and to manage the production system transparently and efficiently. Second, the feature of networks' SPC(KGCS SPC) is that it has a unique dual structure with main and project SPC. Third, SPC influences drama production system in various ways; revitalization of external investment, accounting transparency, growing of network's planning dramas, securing intellectual properties and revenue diversification.

• Publications of The Korean Astronomical Society
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• v.30 no.3
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• pp.811-819
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• 2015

The e-CALLISTO is a network of CALLISTO (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories) spectrometers which detect solar radio bursts 24 hours a day in frequency range 45-870 MHz. The number of channels per spectrum is 200 and the time resolution of whole spectrum is 0.25 second. The Korean e-CALLISTO station was developed by Korea Astronomy and Space Science Institute (KASI) collaborating with Swiss Federal Institute of Technology Zurich (ETH Zurich) since 2007. In this paper, we report replacement of the tracking mount and development of the control program using Visual C++/MFC. The program can make the tracking mount track the Sun and schedule CALLISTO to start and to finish its observation automatically using the Solar Position Algorithm (SPA). Daily tracking errors (RMSE) are 0.0028 degree in azimuthal axis and 0.0019 degree in elevational axis between 2014 January and 2015 July. We expect that the program can save time and labor to make the observations of solar activity for space weather monitoring, and improve CALLISTO data quality due to the stable and precise tracking methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1573-1582
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• 2001

In this paper we analyze the main resources of error in GEO-satellite STFS(Standard Time & frequency Signal) dissemination system. For the case of small countries like Korea, we compare GEO-satellite STFS dissemination technique with the terrestrial network or with the GPS using LEO-satellites, and analyze its advantages over the forementioned systems. We also introduce the GEO-satellite STFS dissemination systems which are being developed or in service. Particularly, we put much efforts to develop the synchronization error calibration technique required to provide a highly accurate STFS service via KoreaSAT. We then propose the differential mode technique as the most effective and efficient calibration technique for mitigating errors in GEO-satellite STFS dissemination systems, and analyze its performance via computer simulation. We also analyze the relation between time accuracy and frequency accuracy. Our experimental results show that the time accuracy is better than 100 ns and the frequency accuracy is better than 10-13 over 7 days all around Korea peninsula. Finally, we propose methods to improve the performance of STFS dissemination system, and demonstrate that the proposed methods result in more accurate synchronization of GEO-satellite STFS.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.195-202
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• 2013

Many communications and broadcast media have emerged by the rapid development of wireless communication and broadcasting technologies, so the radio resources are insufficient for these services. DMB can use the regional integrated channel due to the SFN broadcasting network, so DMB uses the frequency efficiently. However, the domestic DMB uses the existing analog TV frequency band and uses a plurality of channels in some areas because of the interference with the analog TV. However, the broadcasting of the analog TV was terminated, so the channel reallocation of the terrestial DMB is necessary for the efficient use of frequencies. This paper proposes the channel reallocation method of the terrestial DMB and analyzes the change of transmission and reception environments by using simulations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.51-60
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• 2004

DAB(Digital Audio Broadcasting) is a new media service that can provide CD quality audio, various data service, interactive and high quality mobile communications through popular media such as terrestrial broadcasting, satellite, cable TV, and internet. In this paper, a new EPG(Electronic Program Guide) application model is proposed. The model is based on DAB and combines a DAB receiver and PCs so that it can take advantages of using various multimedia services and plenty of internet contents. The developed EPSD(EPG Provider System on DAB) has Web-based Server/Client structure and povides EPG functionalities to client PCs over internet. Therefore, the DAB receiver can be smaller and cheaper, and can develop abundant data services on internet. It can also provide high quality video services and be expected to become an important component in future home network systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.19-29
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• 2001

The Pan-European Digital Audio Broadcasting(DAH) system's performance is characterized and improved with the aid of turbo codec. From the fact that the first bit among the four coded bits at the RCPC coding defined in the Eureka 147 DAD system is not. punctured and always transmitted, this paper proposes a new turbo coded DAB system model that replaces the existing RCPC codec by a turbo codec without modifying the puncturing procedure and puncturing vectors defined in the standard DAB system for compatibility. The performance of a new system is compared to that of the conventional system under the Rician fading channel and the Rayleigh fading channel in conjunction with DAD transmission mode I and III suitable for the terrestrial single frequency network and satellite broadcasting.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.631-636
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• 2010

With the growing trends of communication- broadcasting convergence, a hybrid IPTV that supports both IP network-based on-demand media and terrestrial or cable-based broadcast media is gaining attraction. This paper proposes a rich media framework for hybrid IPTV with support of the latest H.264 codec. For this purpose, we design and implement a media component and a RIA run-time engine customized for TV with the hybrid media. The media component has been designed to provide a uniform and efficient application interface to the various playback methods for RF broadcast and IP-based stored or live media. For performance and portability, it exploits media stream abstraction, adaptive on-demand I-frame search, and automatic calculation of play duration. Based on the proposed media interface, we develop a RIA run-time prototype. It has been carefully designed to fully utilize the built-in graphic acceleration hardware for optimized rendering in the resource-constrained IPTV environments. Demonstration and experiment results validate the performance and usefulness of the developed framework. The framework is expected to be used effectively to support graphics and hybrid media in the applications of IPTV-based VOD, advertisement, and education.