• Journal of Electrical Engineering and Technology
• /
• 제11권2호
• /
• pp.480-489
• /
• 2016

Hidden station problem can occur in power-line communication (PLC) networks. A simple solution to the problem has been proposed to use request-to-send (RTS)/clear-to-send (CTS) exchange, but this approach cannot solve the hidden station problem perfectly. This paper revisits the problem for PLC networks and designs a protocol to solve it. We first analyze the throughput performance degradation when the hidden station problem occurs in PLC networks. Then, we propose an interferer aware multiple access (IAMA) protocol to enhance throughput and fairness performances, which uses unique characteristics of PLC networks. Using the RTS/CTS exchange adaptively, the IAMA protocol protects receiving stations from being interfered with neighboring networks. Through extensive simulations, we show that our proposed protocol outperforms conventional random access protocols in terms of throughput and fairness.

• ETRI Journal
• /
• 제19권3호
• /
• pp.116-140
• /
• 1997

The base station transceiver subsystem (BTS) of the CDMA Mobile System is interfaced to mobile stations over the air and to the wired network through a packet switched interconnection network. The potential benefits of CDMA technology are achieved when the transmitter and the receiver are properly designed and implemented. The physical layer of the interface at the base station is implemented with the CDMA ASICs and control circuits in channel card of the BTS. We present the design perspectives and structural illustration of the BTS. Base station modem ASICs and their control to implement the CDMA receiver, Baseband and RF signal processing blocks, and BTS controller are described. Elaborate power control is essential to ensure the high capacity which is one of advantages of the CDMA technology. The closed loop reverse link power control and the forward link power control operated in the BTS are described.

• Journal of Electrical Engineering and Technology
• /
• 제11권4호
• /
• pp.820-828
• /
• 2016

The sizable electrical load of plug-in electric vehicles may cause a severe low-voltage problem in a distribution network. The voltage drop in a distribution network can be mitigated by limiting the power consumption of a charging station. Then, the charging station operator needs a method for appropriately distributing the restricted power to all plug-in electric vehicles. The existing approaches have practical limitation in terms of the availability of future information and the execution time. Therefore, this study suggests a heuristic method based on priority indexes for fairly distributing the constrained power to all plug-in electric vehicles. In the proposed method, PEVs are ranked using the priority index, which is determined in real time, such that a near-optimal solution can be obtained within a short computation time. Simulations demonstrate that the proposed method is effective in implementation, although its performance is slightly worse than that of the optimal case.

• 한국태양에너지학회 논문집
• /
• 제29권4호
• /
• pp.41-47
• /
• 2009

Wind/diesel hybrid operation can be one of the most effective option for electrical power production at a remote area such as Antarctica. The king Sejong station at Antarctica relies its power production on diesel engines and diesel oil is supplied every other year by ships. However, the oil transportation processes are liable to potential oil spillage caused by the floating ice around the King George island. The long-term storage of the oil at the station can also contaminate the surrounding soils. A l0kW wind turbine has been installed to save oil consumption and operated in connection with the diesel generators since 2006. The diesel engine that operated poorly during the first year of installation was replaced in 2008 to enhance power production an recent measurements indicate that both diesel power quality and the wind turbine availability have been dramatically improved by the replacement. This report discusses electrical power qualities of wind/diesel hybrid system operating at an isolated micro gird located in the king Sejong station. Our experience reveals that the similar technologies can be applied to domestic islands, for example, in the south sea.

• 한국생물환경조절학회:학술대회논문집
• /
• 한국생물환경조절학회 2007년도 춘계 학술대회 및 정기총회
• /
• pp.178-181
• /
• 2007

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2021년도 추계학술대회
• /
• pp.661-663
• /
• 2021

이동통신 시스템에서 기지국에 Outage가 발생하면 해당 기지국에 접속된 단말의 연결 단절로 전체적인 네트워크 성능이 저하된다. 그러므로 Outage를 감지하고 복구하는 것이 중요하다. 본 논문에서는 기지국의 KPI와 이웃 기지국의 네트워크 스캐닝을 이용하여 Outage 기지국을 검출하고, Outage 기지국의 이웃 기지국의 송신전력과 주파수 대역을 변경하여 Outage를 복구하는 기법에 대해 연구하였다. 제안된 기법은 기지국의 KPI 뿐만 아니라 이웃 기지국의 네트워크 스캐닝을 이용하여 Outage 기지국을 검출하기 때문에 기존보다 더 정확한 Outage 기지국을 검출하여 오작동을 줄일 수 있다. 추가적으로, Outage가 발생하면 이웃 기지국의 송신전력과 주파수 대역 변경을 통해 적은 신호 간섭으로 Outage를 복구할 수 있다.

• 한국위성정보통신학회논문지
• /
• 제12권4호
• /
• pp.110-114
• /
• 2017

재난안전망에 소형의 이동무선통신망을 보조적으로 사용하면 소규모의 전파 음영지역 해소, 재난지역의 트래픽 과부하 해소 그리고 접근이 어려운 지역에서 신속하게 재난통신망을 구축하는데 유용하게 활용할 수 있다. 휴대형 이동기지국은 소형의 이동무선망을 구축하는데 필요하며, TVWS(TV White Space)를 활용하는 이동형 기지국은 전파의 활용과 무선망의 구축비용 측면에서 효과적이다. 논문에서는 TVWS에서 동작하는 이동기지국용 전력증폭기를 설계 및 구현하였다. 구현한 전력증폭기는 TV대역인 470 ~ 698MHz에서 동작하며, 이득은 20.1dB 이상, 입출력 반사손실은 11.4dB 이상, 출력을 off 하였을 때 격리도는 39.9dB 이상이었다. 전력증폭기의 IMD(Intermodulation Distortion) 특성은 470MHz에서 18.8dBm을 출력할 때 61.0dBc, 550MHz에서 18.6dBm 출력시 59.3dBc 그리고 690MHz에서 19.0dBm 출력시 56.5dBc의 특성을 갖는다. 본 논문에서 구현한 전력증폭기는 국내 전파법 규정을 만족하므로 이동 기지국용 전력증폭기로 사용할 수 있다.

• Journal of Communications and Networks
• /
• 제17권3호
• /
• pp.231-240
• /
• 2015

To facilitate the base station planning in high speed railway communication systems, it is necessary to consider the functional relationships between the base station transmit power and space parameters such as train velocity and cell radius. Since these functions are able to present some inherent system properties determined by its spatial topology, they will be referred to as the power-space functions in this paper. In light of the fact that the line-of-sight path persists the most power of the received signal of each passing train, this paper considers the average transmission rate and bounds on power-space functions based on the additive white Gaussian noise channel (AWGN) model. As shown by Monte Carlo simulations, using AWGN channel instead of Rician channel introduces very small approximation errors, but a tractable mathematical framework and insightful results. Particularly, lower bounds and upper bounds on the average transmission rate, as well as transmit power as functions of train velocity and cell radius are presented in this paper. It is also proved that to maintain a fixed amount of service or a fixed average transmission rate, the transmit power of a base station needs to be increased exponentially, if the train velocity or cell radius is increased, respectively.

• Nuclear Engineering and Technology
• /
• 제44권3호
• /
• pp.311-322
• /
• 2012

Since the crisis at the Fukushima plants, severe accident progression during a station blackout accident in nuclear power plants is recognized as a very important area for accident management and emergency planning. The purpose of this study is to investigate the comparative characteristics of anticipated severe accident progression among the three typical types of nuclear reactors. A station blackout scenario, where all off-site power is lost and the diesel generators fail, is simulated as an initiating event of a severe accident sequence. In this study a comparative analysis was performed for typical pressurized water reactor (PWR), boiling water reactor (BWR), and pressurized heavy water reactor (PHWR). The study includes the summarization of design differences that would impact severe accident progressions, thermal hydraulic/severe accident phenomenological analysis during a station blackout initiated-severe accident; and an investigation of the core damage process, both within the reactor vessel before it fails and in the containment afterwards, and the resultant impact on the containment.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제16권3호
• /
• pp.231-237
• /
• 2016

Purpose: It is not easy to suggest a quantitative data related to safety analysis. The objective of this paper is to propose a method of Safety Integrity Level (SIL) analysis and to suggest a SIL analysis result for single station controller in nuclear power plant based on IEC 61508. Methods: The Failure Modes and Effects Diagnostic Analysis (FMEDA) and average probability of failure on demand (PFD) are used for SIL assessment. Results: A SIL of single station controller is evaluated 4 by a reliability analysis results and PFD. Conclusion: A SIL analysis method and result for single station controller based on IEC 61508 are proposed in this paper. It can applicable for a manufacturer data in safety-related system.