• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.45-50
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• 2012

무선통신 기술의 발전으로 인해 디지털 라디오 시스템은 아날로그 방송으로 대체되고 있다. In-band 디지털 라디오 시스템은 기존의 아날로그 라디오 주파수를 사용하기 때문에, 기존 방송과의 간섭이 발생할 수 있다. 따라서 디지털 방송을 위해 효과적인 간섭분석은 매우 중요하다. 이 논문에서는 디지털 라디오 시스템의 SINR과 BEP(bit error probability)를 분석하기 위해 각도 효과를 고려한 방법을 제안한다. 여기서 각도 효과는 송신기 주변에 다양한 방향에 수신기가 위치해 있을 때 간섭을 분석할 수 있는 방법을 의미한다. 분석 결과들은 디지털라디오 방송망을 배치하기 위한 기본 정보로 활용될 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1199-1204
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• 2004

In this paper, the DCS (Data Communication System) which is a main part of CBTC (Communication Based Train Control) system is consisted of radio based wireless communication system and optical based wired system. In the radio based wireless communication, the location of AP(Access Point) Enclosure and Antenna shall be optimized for the guaranteed communication channel between wayside and trains either open aired or tunnelled area. This study is introducing the way of determinating optimized positioning the radio based wireless communication equipment in Bundang Line. At this moment, this CBTC project for the KNR's (Korea National Railway) intelligent train control system are in installment phase therefore the simulation data can show only from lab equipment. After the phase I testing, more detailed data can be collected and advanced paper will be issued in a short time.

• 한국통신학회:학술대회논문집
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• 한국통신학회 2004년도 추계종합학술대회 논문 초록집
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• pp.350-350
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• 2004

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.210-215
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• 2003

At present, communication network for subway is making use of the train radio system for main network and normally established a base station every three subway station. It is talk over the telephone between a locomotive and the traffic control for careful train service. Besides, mobile telephone equipment is using for service improve and convenience to passengers such as 011, 016, 017, 019 and what not. However, the train radio system has been occurring a various problems when a state of emergency because it is able to compose only one communication route each base station zone. We could have improving like this problems through induce the TRS(Trunked Radio System), though because have been able to compose multilateral communication route in case of linking with LCX(Leaked Coaxial) cable which is established. Therefore, we could be able to a fitting meet the emergency as train firing etc.. and efficient use of limited frequency resources.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1294-1302
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• 2008

Talk-Back systems comprised of master-equipment at the control room and slave-equipment at turnouts refer to the intercommunication facilities that optimize mutual communication between maintenance staff on trackside and the control room to facilitate quickness and accuracy of train operation control and its maintenance within depot and on mainlines with turnouts for direction switching of the trains in operation. The weakness lies in additional maintenance costs of cables since the Talk-Back system installed on line 1 along with line 2-4 has a profound effect on the voice quality leading to the attenuation and crosstalk of the system due to the deterioration of cables and environmental factors. This paper discusses the Talk-Back system in a radio communication environment with the application of RF(Radio Frequency) communication system from the wire communication system by cables to ameliorate these problems, and deals with the energy saving environmentally friendly facilities in consideration of replacing power section at salve-equipment with solar batteries benefitting the system in light of energy consumption.

• 한국항해학회지
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• 제16권2호
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• pp.53-78
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• 1992

GMDSS-the Global Maritime Distress and Safety system which is utilizing the new technologies such as satellite communication system, DSC and NBCP-is effectuated not only by the amendment of SOLAS but also by the conference of RR and IMO's MSC, and will be the major factor of the variation of the demand and supply of Radio Operators. To cope with the GMDSS voluntarily, regulations relating to the radio installation, the posting of Radio Operators, the bounds of duty, etc. must be established and the demand and supply of Radio Operators which take charge of the system must be accomplished pertinently. In this study, the authors suggested some practical schemes to improve the effect of policy as follow. 1. The Ministry of Communication must supervise strictly the arrangement of Radio Operators, especially relating tot he legally qualified complement of Radio Station, and must review the official certification system to upgrade the quality of Radio Operators. 2. The Ministry of Communication must take overall charge of the qualitifications and technical standards of Radio Operators, the extent of their engagement, etc. which are provided by International Regulations. 3. Relating Administrations must cooperate with Shipping Companies in onboard-training to foster and ensure the manpower of Radio Operators. 4. Institutional devices to drive the resolute investment in education and training for mariners, especially for the ship's officers, must be prepared. 5. The Communication Administration and the Korea Maritime and Port Adminstration(KMPA) must cooperate mutually in the balance of the demand and supply of Radio Operators and use make their best to realize more harmonious policies on the demand and supply of manpower.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.102-107
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• 2012

본 논문에서는 2.1 GHz 대역 다중빔 이동위성통신 시스템과 이동통신 시스템간 간섭 시나리오를 분석하고, 두 시스템간 주파수 공유를 위한 간섭 평가 방법을 제시하였다. 최소결합손실 방법을 이용하여 이동통신 시스템으로부터 이동위성통신 시스템으로의 간섭 및 이동위성통신 시스템으로부터 이동통신 시스템으로의 간섭 분석을 수행하였으며, 분석 결과로부터 두 시스템간의 동일 주파수 공유를 위한 이격 거리를 도출하였다.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.58-63
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• 2013

무선통신 시스템 간의 주파수 간섭은 시스템의 성능을 감소시키거나 운용을 제한할 수 있으므로 신규 시스템의 도입 이전에 기존 시스템들과의 주파수 양립성 평가가 반드시 수행되어야 한다. 본 논문에서는 1.6 GHz 대역 무선항행위성업무 시스템의 인접대역에서 신규 이동통신업무 시스템을 운용하기 위한 양립성 평가 알고리즘을 제시하였으며, 동일 지역 내에서 운용되는 이동통신업무시스템과 무선항행위성업무 시스템 상호 간의 최소결합손실 (Minimum Coupling Loss; MCL) 분석 결과로부터 두 시스템 간의 주파수 공유를 위한 조건을 도출하였다.

• 한국인터넷방송통신학회논문지
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• 제14권3호
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio)는 디지털 TRS(Trunked Radio System)의 유럽 표준으로 재난통신에 특화된 서비스를 제공한다. 특히 TETRA에서 제공하는 DMO(Direct Mode Operation) 기능은 기지국 중계 없이 단말기간 직접통신이 가능하여 기지국 전파가 도달되지 않는 음영지역에 효과적으로 활용된다. 하지만 사용자들이 DMO기능을 보다 효과적으로 활용하기 위해서는 전파도달범위 예측 정보가 제공되어야 한다. 따라서 본 논문에서는 국내에 보급되어 운용 중인 TETRA DMO 단말기의 링크버짓을 계산하고 이를 경로손실 모델에 적용시켜 지역 환경별 전파도달 거리를 예측하였다.

• 천문학논총
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• 제15권spc2호
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• pp.21-25
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• 2000

The ionosphere, the atmosphere of the earth ionized by solar radiations, has been strongly varied with solar activity. The ionosphere varies with the solar cycle, the seasons, the latitudes and during any given day. Radio wave propagation through or in the ionosphere is affected by ionospheric condition so that one needs to consider its effects on operating communication systems normally. For examples, sporadic E may form at any time. It occurs at altitudes between 90 to 140 km (in the E region), and may be spread over a large area or be confined to a small region. Sometimes the sporadic E layer works as a mirror so that the communication signal does not reach the receiver. And radiation from the Sun during large solar flares causes increased ionization in the D region which results in greater absorption of HF radio waves. This phenomenon is called short wave fade-outs. If the flare is large enough, the whole of the HF spectrum can be rendered unusable for a period of time. Due to events on the Sun, sometimes the Earth's magnetic field becomes disturbed. The geomagnetic field and the ionosphere are linked in complex ways and a disturbance in the geomagnetic field can often cause a disturbance in the F region of the ionosphere. An enhancement will not usually concern the HF communicator, but the depression may cause frequencies normally used for communication to be too high with the result that the wave penetrates the ionosphere. Ionospheric storms can occur throughout the solar cycle and are related to coronal mass ejections (CMEs) and coronal holes on the Sun. Except the above mentioned phenomena, there are a lot of things to affect the radio communication. Nowadays, radio technique for probing the terrestrial ionosphere has a tendency to use satellite system such as GPS. To get more accurate information about the variation of the ionospheric electron density, a TEC measurement system is necessary so RRL will operate the system in the near future.