• Journal of Power Electronics
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• 제4권3호
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• pp.138-151
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• 2004

In this paper, a constant frequency phase shifting PWM-controlled voltage source full bridge-type series load resonant high-frequency inverter using the $4^{th}$ generation IGBT power modules is presented for innovative consumer electromagnetic induction heating applications, such as a hot water producer, steamer and super heated steamer. The bridge arm side link passive capacitive snubbers in parallel with each power semiconductor device and AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is evaluated and discussed on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency inverter topology, what is called, DE class type, including the variable-power variable-frequency regulation function can expand zero voltage soft switching commutation area even under low output power setting ranges, which is more suitable and acceptable for newly developed induction heated dual pack fluid heaters. Furthermore, even the lower output power regulation mode of this high-frequency load resonant tank inverter circuit is verified so that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.136.1-136.1
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• 2011

This paper proposes the method to implement the railroad switching point heating system using the hybrid of the photovoltaic and wind power. The goal of the implementation of the railroad switching point heating system is to prevent freezing of the snow in the winter. The heating system of railway used to supply electricity through photovoltaic and wind power to prevent freezing. Hot wires of the railroad switching point heating system are used about 2kW of electric energy at the day. The electric energy of 2kW used the length of the hot wires about 3m. As the ON and/or OFF mode considering the tracks temperature and the ambient temperature, so the way the use of power-saving effect. In addition, the system can be used the railroad switching point heating system in winter and railway signal and street lights around the track in summer. In experiment, we acquired the power data according to time at the day of photovoltaic and wind power. We confirmed the temperature rise using the heating cable for 3m of $85^{\circ}C$, 30W/m. The temperature rise of the heating cable changes the temperature of $5^{\circ}C$ after 10 minutes and $11^{\circ}C$ after 10 minutes. We have confirmed the possibility of the railroad switching point heating system using the hybrid of the photovoltaic and wind power.

• 한국통신학회논문지
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• 제33권7A호
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• pp.710-719
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• 2008

본 논문에서는 OFDM 기반 이동통신시스템에서 idle mode 단말의 전력 소모를 감소시키기 위하여 기존의 프리앰블에 PI(Paging Indicator) 정보를 추가하여 전송하는 기법을 제안한다. L1/L2 제어채널을 사용하여 PI를 전송하는 기법과 비교하여, 프리앰블을 이용하여 PI를 전송하는 기법은 PI 전송을 위한 추가의 overhead가 필요하지 않을 뿐만 아니라 PI 검출을 위한 복잡도도 감소시킬 수 있다. 본 논문에서는 OFDM 기반 이동통신시스템, 특히 mobile WiMAX 시스템에 적합한 동기화 기법과 PI 검출기법에 대하여 기술한다. 모의실험을 통하여 mobile WiMAX 시스템에서 동기화 성능과 셀 탐색 성능을 크게 열화시키지 않으면서 프리앰블(또는 common synch symbol)을 사용하여 PI를 전송할 수 있음을 확인한다.

• 전력전자학회논문지
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• 제17권2호
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• pp.99-106
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• 2012

In this paper, 15[kW] AC regenerative system for battery charging and discharging test is proposed. The regenerative system is able to regenerate surplus energy to the grid in discharging mode, and the inverter of the system can be operated as a converter to compensate scarce energy in charging mode. In case of the conventional DC charging and discharging system, the regenerative energy is consumed by a resistor. However, as the proposed system regenerates the surplus energy to the grid through using DC-AC inverter, the energy saving effect can be achieved. In this paper, 15[kW] battery charging and discharging system is developed, and the validity of the system is verified through simulation and experimental results.

• Journal of Communications and Networks
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• 제7권1호
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• pp.76-86
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• 2005

Today's wireless access networks consist of several tiers that overlap each other. Provisioning of real time undisrupted communication to mobile users, anywhere and anytime through these heterogeneous overlay networks, is a challenging task. We extend the end-to-end approach for the handoff management in hybrid wireless data network by designing a fully mobile-controlled handoff for mobile devices equipped with dual mode interfaces. By handoff, we mean switching the communication between interfaces connected to different subnets. This mobile-controlled handoff scheme reduces the service disruption time during both horizontal and vertical handoffs and does not require any modification in the access networks. We exploit the IP diversity created by the dual interfaces in the overlapping area by simultaneously connecting to different subnets and networks. Power saving is achieved by activating both interfaces only during the handoff period. The performance evaluation of the handoff is carried out by a simple mathematical analysis. The analysis shows that with proper network engineering, exploiting the speed of mobile node and overlapping area between subnets can reduce service disruption and power consumption during handoff significantly. We believe that with more powerful network interfaces our proposal of dual interfaces can be realized.

• 한국정보통신학회논문지
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• 제16권10호
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• pp.2171-2176
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• 2012

PC와 그 주변기기는 실제로 사용하지 않는 대기 상태에서도 많은 전력을 소비한다. 특히 각급 학교나 학원 그리고 사무실에서 사용되는 PC와 그 주변기기는 근무시간에 항시 콘센트에 연결되어 있지만 사용시간은 많지 않으며, 플러그가 전원에 연결되어 있으면 전원이 꺼졌다 하더라도 일정 부분의 전력이 소모된다. 본 논문에서는 일반 사무실 및 홈 네트워크의 PC를 포함한 다양한 주변 기기들의 대기전력을 포함한 전력소모를 관리하기 위한 네트워크 기반의 스마트 플러그 시스템을 개발하고 그 성능을 평가하였다. 본 시스템은 전력관리서버, 네트워크 멀티콘센트, PC 제어를 위한 PC 에이전트 그리고 원격지에서의 관리를 위한 스마트폰 앱으로 구성된다. 본 시스템은 PC와 그 주변기기의 전력을 모발일 환경에서 편리하게 관리할 수 있을 뿐 아니라, 대기전력을 포함한 소비전력을 효율적으로 절감할 수 있다.

• 한국인터넷방송통신학회논문지
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• 제18권1호
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• pp.37-41
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• 2018

본 논문에서는 참고문헌[1] 논문에서 제안한 고유의 링크 스케줄링 방법이 적용된 IEEE802.15.4e TSCH (Time-Slotted Channel Hopping)의 전력 소비 측면에서 절감 능력을 기존 단일채널 IEEE802.15.4와 비교하여 분석한다. TSCH 방식이 기존 방식에 비해 어떤 트래픽 조건하에서도 전력소모가 적게 하는 것으로 나타난다. 그 이유는 첫째, 충돌이 발생하지 않는 스케줄링 방식으로 인해 백오프 시간이 없다는 점과 둘째, MAC 오프셋 시간변수들의 차이로 인한 것으로 판단된다. 마지막으로 TSCH에서는 디바이스들은 자신의 스케줄이 아닌 타임 슬롯 동안은 sleep을 통해 전력 소모를 줄일 수 있음을 볼 수 있다.

• 전기학회논문지P
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• 제59권2호
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• pp.158-162
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• 2010

PSD is automatically opened and closed when subway train arrive on the station. This system was designed to control electric automatic system. These doors will provide passenger safety, energy saving and a good environment in subway. The monitoring and control systems of PSD are configured so that they can be operated in automatic mode in connection with ATO through the composite control panel in the station control room. The objective of this paper is to obtain high reliability that is essential for monitoring and control systems of PSD. The power supply is based on protection circuit using DC power bridge from two UPS. Also, stable communication system consists of CAN communication line redundancy and RF cross protection algorithm. Monitoring state display results show the validity of the proposed high reliability monitoring and control systems of PSD.

• 조명전기설비학회논문지
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• 제23권7호
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• pp.75-80
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• 2009

In this study, a Web server was constructed using LabVIEW's DataSocket, which makes possible acquisition, analysis, and saving in real time. The output value of the optical current sensor at the web server PC was measured and the output value was displayed using the Web browser of the client PC. DataSocket by LabVIEW makes the construction of a Web server easier than other languages and is compatible with other application programs. An optical current sensor was composed using a 1310 [nm] laser diode, and 9/125 [${\mu}m$] standard single mode optical fiber and was created to be a close type sensor. Data measurement using Web servers has the advantage of monitoring electric power systems at a great distance and can fuse IT technology and electric power systems. Also, this measurement uses inexpensive mounting and programming when compared to existing measurement equipment allowing the construction of a measurement system in any situation or surrounding.

• 드라이브 ㆍ 컨트롤
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• 제13권4호
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• pp.31-44
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• 2016

In recent hydraulic actuation systems, conventional hydraulic spool valves with pressure compensators are becoming less popular, after the introduction of the independent metering concept for valves. Within this concept, four valves are needed for actuating a single cylinder. Subsequently, this increases the freedom of controlling both chamber pressures of the cylinder, and it then provides for electronically-controlled pressure compensation facilities. Additionally, this has the potential to save valuable energy. The primary focus of this paper is to develop a new generation of hydraulic circuits using the independent metering valve (IMV). This configuration can function well as a conventional IMV circuit while providing better pressure control. We first describe the working principles of five distinct modes of the proposed IMV system. Then, mathematical models for each working mode are presented. Finally, we present numerical simulations that have been carried out to evaluate the system performance, in comparison with that of the conventional IMV configuration. The simulation results demonstrate that the performance of the new IMV configuration is superior to the conventional IMV system in terms of energy savings.