• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.83.2-83.2
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• 2015

The Goheung radio interferometer with three 1.8-m antennas has been installed at National Youth Space Center in Goheung, Korea. The interferometric observation of the Sun using the Goheung radio interferometer was carried out and the observed data was analysed to construct the radio contour map of the Sun in 2014. The specifications of Goheung radio interferometer and the synthesized interferometer map of the Sun are provided. As a science activity center for youth, we currently provide students some experimental activities based on the principle of radio observation and interferometer. Our goal is to encourage youth to be interested in astronomy by engaging real experience of radio observation and constructing a synthesized interferometer map with observed data.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.4
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• pp.235-243
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• 2008

In this paper, a software-based Digital Radio Modiale(DRM) receiver is implemented on a Digital Signal Processor(DSP). DRM stands for the European radio broadcasting standard to bring AM radio into digital radio, designed to work at frequencies below 30MHz. DRM can offer various data services such as text messaging and slideshow services as well as audio services. The DRM receiver implemented on the Tensilica DSP core performs well at low signal strength indication of -102dBm.

• Journal of The Korean Astronomical Society
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• v.49 no.3
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• pp.83-92
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• 2016

The Toothbrush radio relic associated with the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index, M_radio ≈ 2.8, is larger than that estimated from X-ray observations, M_X ≲ 1.5, we consider the re-acceleration model in which a weak shock of M_s ≈ 1.2 - 1.5 sweeps through the intracluster plasma with a preshock population of relativistic electrons. We find the models with a power-law momentum spectrum with the slope, s ≈ 4.6, and the cutoff Lorentz factor, γ_e,c ≈ 7-8×10⁴ can reproduce reasonably well the observed profiles of radio uxes and integrated radio spectrum of the head portion of the Toothbrush relic. This study confirms the strong connection between the ubiquitous presence of fossil relativistic plasma originated from AGNs and the shock-acceleration model of radio relics in the intracluster medium.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.550-552
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• 2004

In this paper, access protocol is proposed that can optimally control the radio buoy system used for inshore and deep sea fishery. Proposed protocol can minimize the power consumption of radio buoy and can ensure high security from burglary and loss, and it enable a mother ship to control remotely more than 150 radio buoys simultaneously. GPS technology and remote control techniques are used to monitor the exact location and status of the radio buoy system in real time.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.94-100
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• 2012

Radio interference has been occurring in mobile communication services on the southern seashore in Korea. Monitoring the radio interference signal revealed that the main reason for the radio interference was a radio ducting signal coming from the seaside of Japan. In this paper, we have analyzed the effect of interference on WiMAX service using a 2.5 GHz frequency band between Korea and Japan. We focus on the interference scenario from base station to base station and we use the Minimum Coupling Loss (MCL) method for interference analysis and the Advanced Propagation Model (APM) for calculating the propagation loss in ducts. The propagation model is also compared with experimental measurement data. We confirm that the interfering signal strength depends on the antenna height and this result can be applied to deployment planning for each system with an interference impact acceptable to both parties.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.725-725
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• 2006

• Electronics and Telecommunications Trends
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• v.35 no.5
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• pp.69-82
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• 2020

In many technologies, artificial intelligence (AI) is becoming an important topic for areas based on the field of big data. However, applied AI cases and the research status of radio wave technology are not widely known to the public. The spread of AI to other areas is being followed by radio wave technologies, and much effort is being taken to evolve it into intelligent radio wave technologies in the future. This paper presents the recent areas of interest in radio wave technology, such as spectral sharing, illegal spectrum monitoring, radar detection, radio wave medical imaging, and channel modeling; examines the requirements for applying AI; and describes the applied cases, research trends, and standardization efforts that apply AI technology to them. On this basis, we will discuss the prospects of AI application to the expected radio wave technology of the future.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.576-580
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• 2003

In order to assess the spectrum usage efficiency in mobile radio services, we consider the capacity limits of a CDMA system. The maximum achievable capacity per $km^2$ is viewed as a meaningful figure of merit for a cellular system and a method is proposed here to estimate the minimum achievable distance between adjacent base stations in the case of CDMA. The probability for entering in soft handover state is used as a limit for densification in a CDMA system. From this criterion, conditions on the minimum possible cell radius are derived.

• Journal of applied mathematics & informatics
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• v.35 no.1_2
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• pp.59-74
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• 2017

A radio labeling of a graph G is a function $f:V(G){\rightarrow}\{1,2,{\ldots},k\}$ with the property that ${\mid}f(u)-f(v){\mid}{\geq}1+diam(G)-d(u,v)$ for every pair of vertices $u,v{\in}V(G)$, where diam(G) and d(u, v) are diameter and distance between u and v in the graph G respectively. The radio number of a graph G, denoted by rn(G), is the smallest integer k such that G admits a radio labeling. In this paper, we completely determine radio number of all transformation graphs of a path.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.363-365
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• 2002

train radio system used for shinkansen in japan has been 18 years since it was opened in 1982 and grown old. Analogue train radio is short of the number of lines and can't cope with the needs for the new high speed data transmission by 1,200 bps. The construction to renew the Tohoku - Joethu shinkansen train radio system(shinkansen train radio system) with digital method started from 2000 in JREast Digital method makes it possible to improve the quality of radio transmission, reliability of the network and every device, the speed and capacity of transmission and to be more efficient maintenance by introducing the latest IT technology. This paper will consider synchronization between base station. diversity method. software receiver, mobile high speed digital radio system, high reliability LAN introduced as technologies supporting these.