• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.179-188
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• 2003

Advances in wireless networking technology has engendered a new paradigm of computing, called mobile computing, in which users carrying portable devices have access to a shared infrastructure independent of their physical locations. Wireless communication has some restraints such as disconnection, low bandwidth, a variation of available bandwidth, network heterogeneity, security risk, small storage, and low power. Power adaptation routing scheme overcome the shortage of power by adjusting the output power, was proposed. Existing power saving routing algorithm has some minor effect such as seceding from shortest path to minimize the power consumption, and number of nodes that Participate in routing than optimal because it select a next node with considering only consuming power. This paper supplements the weak point in the existing power saving routing algorithm as considering the gradual approach to final destination and the number of optimal nodes that participate in routing.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.365-371
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• 2017

IEEE 802.11 Wireless Local Area Network (WLAN) adopts Power Saving Mode(PSM) to save the power. Unlike existing PSM, this paper proposes a new scheme for the power saving of the Mobile Host(MH) when a MH performs the data transmission after the competition-based DCF(Distributed Coordination Function) and competition free-based PCF(Point Coordination Function). In this paper, The proposed scheme estimates the distance between the MH with the authority of data transmission and the Access Point(AP) and then adaptively controls the power of the MH considering the distance. Through the simulation result, we find that the proposed scheme consumes the smaller transmission power and has the similar success rate of packet transmission when it is compared to the existing scheme which uses the same power without the consideration of the distance.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.15-16
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1153-1155
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• 2008

Color dimming technology has been developed for high color gamut and aggressive power saving. In our new algorithm, we proposed a new concept of 'color class', with which it is possible to control RGB color luminance effectively and exactly. We reached color gamut of 155% of NTSC 1976 and reduced power consumption under 100 watt for 46 inch LCD.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.207-212
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• 2015

Wi-Fi Direct allows battery powered mobile devices to form a wireless ad hoc network. Since one member of the network called Group Owner (GO) takes the role of managing the network, the network lifetime is mainly affected by the energy efficiency of GO. Hence, Wi-Fi Direct defines power saving schemes that allow GO to save the energy by turning off its radio interface during the periods called absence periods. However, the Wi-Fi Direct specification does not specify how to set parameters (denoted by PS parameters) determining the schedule of the absence periods. In this paper, we therefore propose a novel traffic-aware power saving scheme for Wi-Fi Direct networks. In particular, the proposed scheme estimates the application-level traffic load and adaptively tunes the PS parameters according to the estimated value.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1113-1119
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• 2007

In this paper, first, we proposed various possible candidate schemes for determining initial sleep window size and varying sleep window size in sleep mode for power saving class I of IEEE 802.16e. Then, we analyzed and compared the power saving performances of those schemes. The schemes used for the comparisons are EICV of IEEE 802.16e, and other comparable schemes such as EIED, EILD, LIED and LILD. Experimental results show that LILD and EIED outperform other comparable schemes. Especially, EIED shows the better performances for the case of high traffic intensity environments, while LILD does for the low traffic intensity case.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.1
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• pp.67-74
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• 2014

Most of steam power plants in Korea are using the method of heating the feed water whenever the ambient temperature around the power plant area below $5^{\circ}C$ to prevent freezing water flowing in the pipe in winter time. But this kind of heat supplying system is not useful to save energy. If we take the method that the temperature of the each pipe is controled by direct measure of temperature by attaching sensor on the outside surface of the feed water tubes, then we can expect that a plenty of energy can be saved. In this study, the computer simulation is used to compare the energy consumption loads of both systems. Energy saving rate is calculated for the location of Incheon area in winter season. Four convection heat transfer coefficients for the ambient air and three initial flowing water temperature inside the tube were used. The result shows that the temperature control system using sensor represents more than 95% of energy saving rate in Incheon area. Even in the severe January weather condition, the energy saving rate is almost 75% in two days basis and even 83% in one day basis.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.81-91
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• 2008

In mobile wireless communications, there is a new approach that uses the lacking spectrum efficiently. A cognitive radio is a device that can changes its transmitter parameters based on interaction with the environment in which it operates. At present, the wireless communication standard for wireless device contains power-saving modes or energy efficient mechanisms which cuts off the power of transmitter and receiver for power-saving. However, in cognitive radio environment, every device has the Quiet Period for searching channel and existing energy-saving method is not appropriate to be adjust to cognitive radio environment. In this paper, we propose an energy-efficient MAC protocol of mobile device in cognitive radio environment and prove the improvement of proposed method.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.51-55
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• 2013

The purpose of this study is to find the causes of malfunctions and defective operation of printed circuit boards(PCBs) built into home refrigerators to perform power saving functions. This study performed an electrostatic test of a PCB built-in using an Auto Triggering system; lightning and impulse tests using an LSS-15AX; and an impulse test using an INS-400AX. From the analysis of a secondarily developed product, it was found that electrostatic discharge(ESD) caused more malfunctions and defective operations than electric overstress(EOS) due to overvoltage. As a result of increasing the condenser capacity of the PCB circuit, withstanding voltage was increased to 7.4 kV. In addition, this study changed the power saving mode and connected a varistor to the #2 pin of an IC chip. As a result, the system consisting of all specimens of a finally developed product was operated stably with an applied voltage of less than 10 kV. This study found it necessary to perform quality control at the manufacturing stage in order to reduce the occurrence of electrostatic accidents to IC chips built into a PCB.