• The Bulletin of The Korean Astronomical Society
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• v.31 no.2
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• pp.29.1-29.1
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• 2006

• ETRI Journal
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• v.42 no.5
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• pp.643-657
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• 2020

Sixth generation will exploit satellite, aerial, and terrestrial platforms jointly to improve radio access capability and unlock the support of on-demand edge cloud services in three-dimensional (3D) space, by incorporating mobile edge computing (MEC) functionalities on aerial platforms and low-orbit satellites. This will extend the MEC support to devices and network elements in the sky and forge a space-borne MEC, enabling intelligent, personalized, and distributed on-demand services. End users will experience the impression of being surrounded by a distributed computer, fulfilling their requests with apparently zero latency. In this paper, we consider an architecture that provides communication, computation, and caching (C3) services on demand, anytime, and everywhere in 3D space, integrating conventional ground (terrestrial) base stations and flying (non-terrestrial) nodes. Given the complexity of the overall network, the C3 resources and management of aerial devices need to be jointly orchestrated via artificial intelligence-based algorithms, exploiting virtualized network functions dynamically deployed in a distributed manner across terrestrial and non-terrestrial nodes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5007-5014
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• 2010

Recently n Korea, the House of Commons and terrestrial broadcasting facilities integrated with FM radio and the satellite compulsory was amended to transfer MATV(Master Antenna Television) adjusted by SMATV(Satellite Master Antenna Television). While the SMATV was accepted by default in most other countries, our county did not accept it as the default for broadcast. Because domestic cable and satellite television service providers are conflicts with their interest. bAs a result, the hybrid amplifier for SMATV technology development and volume production for the state is insufficient. Therefore, terrestrial television broadcast bands (54 ~ 806Mhz) and FM radio broadcast band (88 ~ 108Mhz) band satellite with (950 ~ 2150Mhz) to amplify the development of a broadband amplifier with subsequent resolution of problems is also presented in this study.

• Journal of information and communication convergence engineering
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• v.15 no.3
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• pp.143-150
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• 2017

Absorption of microwave radio frequency signal by atmospheric rain is prevalent at frequencies above 10 GHz. This paper presents the studies on rain attenuation at 18 GHz for 3.2 km experimental link between Khumdang (Korea Telecom, KT station) and Icheon (National Radio Research Agency, RRA station). The received signal data for rain attenuation and rain rate were collected at 10 second intervals over a three year periods from 2013 to 2015. Out of several models, the paper present discussion and comparison of ITU-R P.530-16 model, Moupfouma model, Da Silva Mello model along with suitable rain attenuation prediction method. The limitation of research lies on the experimental system that is set up in only one location, however, the preliminary results indicate the application of suitable 1-minute rain attenuation model for specific site. The method provides useful information for microwave engineers and researchers in making decision over the choice of most suitable rain attenuation prediction in terrestrial links.

• Journal of Broadcast Engineering
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• v.7 no.3
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• pp.271-276
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• 2002

It is very important to find errors in broadcasted streams because it can help us to find where errors occur. Broadcasted streams may have errors in the RF(radio frequency) or baseband domain. It is very important to fix these errors because it can help to stabilize set-top boxes, provide stable receiving, and give comfortable environments to watch TV. Since 2001, major terrestrial broadcasters in Korea started the DTV broadcasting in Kwan-Ak over Seoul area. In this paper, we provide some analysis on errors in MPEG-based TS streams, PSIP packets, and RF area which may occur in DTV systems and compare this result with that of USA.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.367-376
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• 2011

In this paper, we propose self-organizing schemes for the initial configuration of the neighbor cell list (NCL), maintenance of the NCL, and physical cell identifier (PCI) allocation in heterogeneous networks such as long term evolution systems where lower transmission power nodes are additionally deployed in macrocell networks. Accurate NCL maintenance is required for efficient PCI allocation and for avoiding handover delay and redundantly increased system overhead. Proposed self-organizing schemes for the initial NCL configuration and PCI allocation are based on evolved universal terrestrial radio access network NodeB (eNB) scanning that measures reference signal to interference and noise ratio and reference symbol received power, respectively, transmitted from adjacent eNBs. On the other hand, the maintenance of the NCL is managed by adding or removing cells based on periodic user equipment measurements. We provide performance analysis of the proposed schemes under various scenarios in the respects of NCL detection probability, NCL false alarm rate, handover delay area ratio, PCI conflict ratio, etc.

• Journal of IKEEE
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• v.20 no.1
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• pp.54-60
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• 2016

In this paper, out-of-band emission regulations and measurement methods of terrestrial DTV broadcasting services are analyzed, and a novel method to evaluate the out-of-band emission characteristics of DTV transmitter is proposed. Experimental results show that proposed method can be easily used to measure the characteristics of DTV transmitter with inexpensive measuring equipments. With a few modifications, proposed method can be widely adopted to measure the RF performances of the general radio equipments efficiently.

• Journal of Astronomy and Space Sciences
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• v.18 no.1
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• pp.27-32
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• 2001

A statistical study has been performed of the magnetic storm recovery phase using the Dst index for 102 storm events in the interval January 1996 to December 1998. In 43 cases (or 42%) out of our 102 events, the recovery phase exhibits fast recovery (kaking about 8 hours or less) at its initial stage or for the entire recovery period. Since this fast recovery can be explained by the fast charge exchange less of $O^{+}$ ions which mostly com from the ionosphere, and since a fraction of $H^{+}$ ions is of ionospheric origin as well, our statistical result supports the view that the source of ring current ions in many magnetic storms can be terrestrial.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.45-54
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• 2009

TETRA(Terrestrial Trunked Radio) is the standard of D-TRS(Digital Trunked Radio System) developed by the ETSI(European Telecommunications Standards Institute). Currently, TETRA has been selected as Electric Power IT Wireless Backbone Network. Traditional distribution automation system has used the wireless network of Mobile Service Provider using CDMA(Code-Division Multiple Access) and WCDMA(Wideband CDMA) modem. Therefore, the development of gateway platform is indispensable according to the change to TETRA network. In this paper, we propose an embedded Linux-based Gateway platform for transmitting Industrial Electric Power IT protocol using TETRA network.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.