• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.254-260
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• 2018

In this study, we suggest an emulator for generating multiple heterogeneous interference signals in the Korean radio frequency identification/ubiquitous sensor network (RFID/USN) frequency band. The proposed emulator uses only one universal software radio peripheral to generate multiple heterogeneous interference signals more economically. Moreover, the physical and media access control parameters can be adjusted in real time using the LabVIEW program, thereby making it possible to create various time-varying interference environments easily. As an example showing the capability of the proposed emulator, multiple interference signals consisting of a frequency-hopping RFID signal and two LoRa signals with different spreading factors were generated. The generated signals were confirmed in both frequency and time domains. From the experimental results, we verified that our emulator could successfully generate multiple heterogeneous interference signals with different frequency and time domain characteristics.

• Journal of electromagnetic engineering and science
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• 제12권1호
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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.

• Journal of electromagnetic engineering and science
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• 제9권4호
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• pp.182-187
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• 2009

When we assign frequency resources to a new radio service, the existing services need not to be interfered with by the new service. Therefore, when we make a frequency assignment, a guard band is necessary to separate adjacent frequency bands so that both can transmit simultaneously without interfering with each other. In this paper, we propose an efficient frequency guard band decision rule for avoiding interference between radio services. The guard band is established based on the probability of interference in the previously arranged scenario. The interference probability is calculated using the spectrum engineering advanced Monte Carlo(MC) analysis tool(SEAMCAT). After applying the proposed algorithm to set up the frequency guard band, we can decide on the guard band appropriately because the result satisfies the predefined criterion.

• 천문학논총
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• 제30권2호
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• pp.691-693
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• 2015

Radio sources are very weak, as they can travel through large distances. Radio sources also have photons with low energies compared to others electromagnetic waves (EM). Microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and the most energetic electromagnetic wave is gamma-rays. Radio astronomy studies are restricted due to radio frequency interference (RFI) produced by people. If this disturbance is not minimized, it poses critical problems for astrophysical studies. The purpose of this paper is to profile RFI maps in Peninsular Malaysia with a minimum mapping technique for RFI interference. Decision-making processes using GIS (Geographical Information System) for the selection requires gathering information for a variety of parameters. These factors affecting the selection process are also taken into account. In this study, various factors or parameters are involved, such as the availability of telecommunications transmission (including radio and television), rainfall, water lines and human activity. This mapping step must be followed by RFI site testing in order to identify areas of low RFI. This study will benefit radio astronomy research, especially regarding the RFI profile.

• Journal of electromagnetic engineering and science
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• 제18권1호
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• pp.58-62
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• 2018

In this study, we propose a software-defined radio-based frequency interference emulator in the space-time domain. This emulator can easily model actual interference environments because of the versatile programming capability of the universal software radio peripheral and LabVIEW. As an example of an interfering network using the contention-based multiple access scheme in the time domain, we emulate a coordinated Wi-Fi network that consists of one access point and two Wi-Fi nodes. Results show that our emulator can successfully model multiple interfering signals in the Wi-Fi network and easily adjust various space-time domain parameters.

• Journal of electromagnetic engineering and science
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• 제6권1호
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• pp.76-81
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• 2006

Ultra wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as Broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a orthogonal frequency division Multiplex UWB source and an impulse radio UWB source, to a Broadcasting transmission system. The receive power degradations of broadcasting system are presented. From these experimental results, we show that in all practical cases UWB system can coexist 35 m distance in-band broadcasting network.

• 한국전자파학회논문지
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• 제13권2호
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• pp.196-208
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• 2002

국내 남해안 일대에서 1994년부터 주파수공용통신(TRS) 서비스에 간섭이 처음 발생한 이후, 최근 셀룰러 이동통신 주파수대역에서도 유사한 간섭 현상이 발생하고 있다. 측정 결과 그 간섭원이 일본의 디지털 셀룰러 이동서비스의 기지국인 것으로 밝혀졌으며, 이는 일본의 디지털 이동전화 기지국의 송신주파수와 국내의 TRS 및 셀룰러 이동통신 기지국의 수신주파수가 중첩되기 때문이다. 한국과 일본간의 거리가 240~300 km임을 고려할때 간섭의 주 원인을 덕팅현상으로 결론 지을 수 있다. 본 논문에서는 split-step DMFT 알고리즘윽 이용하여 덕팅채널을 통한 전자파 전파를 모델링하고, 동해안과 서해 지역의 실재 측정된 굴절율 profile에 대한 시뮬레이션 결과를 분석하였다.

• 한국전자파학회논문지
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• 제27권10호
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• pp.945-948
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• 2016

최근 프리미엄급 스마트폰들은 대부분 메탈 프레임을 채용하고 있으며, 이는 중저가 스마트폰으로 확산되고 있는 추세이다. 하지만, 메탈 프레임은 스마트폰 내 디지털 부품에서 발생하는 전자파 노이즈의 좋은 전달 경로가 되어, 스마트폰 상단부 또는 하단부에 위치한 무선 안테나에 전자파 간섭을 일으키는 원인이 될 수 있다. 본 논문에서는 메탈 프레임에 EBG(Electromagnetic Band Gap) 구조를 적용하여 안테나로의 전자파 간섭을 줄일 수 있는 방법을 제안하였다. $7{\times}6$ 배열의 다중 비아(Multi-via) EBG 구조를 갖는 메탈 프레임을 설계하였으며, 이를 적용할 경우, 메탈 프레임을 통한 표면 전자파 노이즈 간섭을 20 dB 정도 저감시킬 수 있음을 시뮬레이션을 통해 확인하였다.

• Journal of electromagnetic engineering and science
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• 제9권3호
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• pp.141-145
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• 2009

Interference scenarios involving and a methodology for a terrestrial international mobile telecommunication(IMT) system and mobile-satellite service(MSS) system in a co-channel environment are established. Taking into account a practical deployment situation for both systems, a computational simulation of interference in terms of the ratio of interference power to thermal noise(I/N) is performed in order to evaluate the co-frequency interference with the IMT system caused by the MSS system. The methodology and results could be used for planning an IMT deployment without an unacceptable interference impact caused by the MSS system.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.567-571
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• 2003

Owing to the insufficient satellite resources such as frequency and orbit, the interest in the sharing of these resources has been increasing. ITU-R has been studying on the power limitation, the interference mitigation techniques etc. in order to facilitate the frequency sharing between different systems. Therefore, we studied on the interference mitigation techniques between HEO FSS system and GSO FSS network. We performed the simulation using four mitigation techniques and, based on the results of simulation, evaluated these techniques.