• Journal of the Institute of Electronics and Information Engineers
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• 제52권10호
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• pp.161-167
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• 2015

This paper presented an occupancy-based energy saving system for appliance energy saving in smart house. The developed system is composed of a sensing system and a home gateway system. The sensing system is set of wireless sensor nodes which have pyroelectric infrared (PIR) sensor to detect a motion of human and set of smart plugs which measure the current using CT (current transformer) sensor and send the current to home gateway wirelessly. We measured current consumption of appliances in real time using smart plugs, and checked the occupation of residents using occupancy sensors installed on the door and room. The proposed system saves electric energy to switch off the supply power of unnecessary usages in the unoccupied spaces. Experiments conducted have shown that electric energy usage of appliances can be saved about 34% checked by using occupation.

• The Transactions of the Korea Information Processing Society
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• 제7권8S호
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• pp.2587-2596
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• 2000

본 논문은 ATM-Forum의 WATM 기반 제3세대 무선 멀티미디어 망 환경에서 하나의 M.E.SW(Mobility Enabled ATM Switch)가 단순화된 많은 AP들을 관리하는 방안에 대하여 고려하였다. 또한 WATM 망 환경에서 가변 그룹 크기와 동적인 그룹 페이징 순서 방법을 사용하는 효율적인 페이징 방안을 제안하였다. 그리고 제안한 방안과 기존의 방안에 대해 성능을 평가 및 분석하였다. 여기서는 blanket-polling, sequential-polling 그리고 고정크기 그룹화 방안과 같은 대부분의 기존 방안들을 제안한 가변적이면서 동적인 그룹화 방안과 비교 분석하였다. 분석결과 offered-load가 낮은 환경에서는 단순한 blanket-polling paging 방안이 약간 더 우수한 성능을 보였다. 그러나 트래픽 밀도가 높아지면서 제안한 방안이 기존의 방안들 보다 더 우수한 성능을 보였다. 성능개선은 주로 가변적인 그룹 크기와 MS(Mobile Station)기반 동적인 페이징 순서 방안에 기인한다. 또한 제안한 방안은 MS에 대한 아주 간단한 이력정보와 최종적으로 통신한 AP 정보만이 필요하다. 따라서 이 방안은 효율적으로 구현하는 것이 가능하다.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제21권11호
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• pp.2836-2849
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• 1996

Over ATM network, variable bit rate(or VBR) traffic is allowed. Control of VBR traffic is allowed. Control of VBR traffic becomes difficult if it is bursty. VBR video traffic becomes so much bursty during intra frame period that much cell loss would occur when satistical multiplexed in ATM swich. To aviod cellloss, extra communication resources should be allocated, which reduces the capability of an ATM channel. In this paper, we propose two methods which enable a channel limited in resources to serve more VBR MPEG video bit streams. Firstly, we could redue the bitrate fluction of a statiscally multiplexed bundle of VBR video bit streams by reducing the number of intra frames overlapped at the same frame period. This method can be used in ATM switch which controls multiple video sources. Secondary, in two layer enoding, statistical multiplexing gains can be icreased by letting peak bit rate durations of both layers not be overlapped. This results in more smooth traffic. The performance of proposed methods are demonstrated by a proposed calculation method of statistical multiplexing gains(or SMGs.) The proposed SMG is based on both delay and cell loss QoS requirements at the same time.

• ETRI Journal
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• 제29권4호
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• IEMEK Journal of Embedded Systems and Applications
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• 제4권2호
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• pp.79-83
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• 2009

Streaming Technology can support the real-time playback without downloading and storing multimedia data in local HDD. So, client browser or plug-in can represent multimedia data before the end of file transmission using streaming technology. Recently, the demand for efficient real-time playback and transmission of large amounts of multimedia data is growing rapidly. But most users' connections over network are not fast and stable enough to download large chunks of multimedia data. In this paper, we propose an intelligent IP streaming system based on personalized media service. The proposed IP streaming system enables users to get an intelligent recommendation of multimedia contents based on the user preference information stored on the streaming server or the home media server. The supposed intelligent IP streaming system consists of Server Metadata Agent, Pumping Server, Contents Storage Server, Client Metadata Agent and Streaming Player. And in order to implement the personalized media service, the user information, user preference information and client device information are managed under database concept. Moreover, users are assured of seamless access of streamed content event if they switch to another client device by implementing streaming system based on user identification and device information. We evaluate our approach with manufacturing home server system and simulation results.

• Journal of the Korea Society of Computer and Information
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• 제8권4호
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• pp.117-125
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• 2003

The proposed mechanism has an group management server, which manages the information about both the receivers and the senders. Any receiver can dynamically join/leave the multicast VC. The signaling overload due to group membership changes is not concentrated on the sender, but it is distributed to many receivers for the scalability improvement. The associated signaling messages propagates from the receivers to the ATM switch dedicated to the multicast VC, and hence no signaling overload exists in the shared links there is no latency for the receiver to wait. Our proposed scheme is superior in the view of scalability, the efficiency and the latency to other schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제5권5호
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• pp.931-940
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• 2001

In this paper, I propose Fuzzy Policing Mechanism(FPM) over ATM networks for the control of traffic which is unpredictable and bursty source. The FPM is consist of counter, subtracter and Fuzzy Logic Controller(FLC). The FLC is divided to fuzzifier, inference engine and defuzzifer The output of FLC inputs to the subtractor and it controls the counter. The counter works as a switch in transmission of cells. In simulation, I compared the FPM with the Leaky Bucket algorithm(LBM) in cell loss probability and performance characteristics. As a result, FPM gives lower cell loss probability than that of LBM and has good response behavior The FPM efficiently controls the transmission of packets which are variable traffic source and, it also has good selectivity.

• Proceedings of the KIEE Conference
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.223-225
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• 2008

In order to apply SFCLs into electric power systems, the urgent issues to be settled are as follows, such as initial installation price, operation and maintenance cost due to ac loss of superconductor and the life of cryostat, and high voltage and high current problems. We designed novel hybrid SFCLs which combine superconductor and conventional electric equipments including a vacuum interrupter, an electro-magnetic contactor and a current limiting reactor. The main purpose of the hybrid SFCL is to drastically reduce total usage of superconductor by adopting current commutation method by use of the superconductor and the fast switch. According to protective coordination and performance, we investigated two concepts of Hybrid SFCLs. First is a half cycle fault current limitation type and second is a non-half cycle fault current limitation type. We concluded that the non-half cycle fault current limitation type is batter than the other.

• The KIPS Transactions:PartA
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• 제8A권2호
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• pp.147-156
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• 2001

A high performance routing switch is an essential device to either the high performance parallel processing or communication networks that handle multimedia transfer systems such as VOD. The high performance routing chip called STC104 is a typical example in the technical aspect which has 32 bidirectional links of 100Mbps transfer sped. It has exploited new technologies, such as wormhole routing, interval labeling, and adaptive routing method. The high speed router has been applied into some parallel processing system as a single chip. However, its performance over the various interconnection networks with multiple routing chips has not been studied. In this paper, the strucrtures and characteristics of the STC104 have been investigated in order to evaluate the high speed router. Various topology of the STC104, such as meshes, torus, and N-cube are defined and constructed. Algorithms of packet transmission have been proposed based on the interval labeling and the group adaptive routing method implemented in the interconnected network. Multicast algorithms, which are often requited to the processor networks and broadcasting systems, modified from U-mesh and U-torus algorithms have also been proposed overcoming the problems of point-to-point communication.

• Journal of Power Electronics
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• 제17권5호
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• pp.1173-1185
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• 2017

In this paper, a new single phase multilevel inverter topology with a single DC source is presented. The proposed topology is developed based on the concepts of the L-Z source inverter and the switched capacitor multilevel inverter. The input voltage to the proposed inverter is boosted by two steps: the first step by an impedance network and the second step by switched capacitor units. Compared to other existing topologies, the presented topology can produce a higher boosted multilevel output voltage while using a smaller number of components. In addition, it provides more flexibility to control boosting factor, size, cost and complexity of the inverter. The proposed inverter possesses all the advantages of the L-Z source inverter and the switched capacitor multilevel inverter like controlling the start-up inrush current and capacitor voltage balancing using a simple switching strategy. The operating principle and general expression for the different parameters of the proposed topology are presented in detail. A phase disposition pulse width modulation strategy has been developed to switch the inverter. The effectiveness of the topology is verified by extensive simulation and experimental studies on a 7-level inverter structure.