• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1854-1860
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• 2014

In this paper, the energy saving on mobile communication repeater is studied. DB(Dual Band) small repeater, which is currently used in the field for indoor coverage, is adopted as a test unit. For reducing the power consumption, PFC (Power Factor Correction) is included on SMPS (Switching Mode Power Supply) of the DB small repeater. The test results show that approximately 38.9% of the power consumption is reduced comparing with the repeater without PFC. It means that approximately 230.43kWh per unit can be saved annually.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1393-1405
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• 2017

It is well known that duty-cycling control by dynamically adjusting the polling interval according to the traffic loads can effectively achieve power saving in wireless sensor networks. Thus, there has been a significant research effort in developing polling interval adaptation schemes. Especially, Dynamic Low Power Listening (DLPL) scheme is one of the most widely adopted open-looping polling interval adaptation techniques in wireless sensor networks. In DLPL scheme, if consecutive idle (busy) samplings reach a given fixed threshold, the polling interval is increased (decreased). However, due to the trial-and-error based approach, it may significantly deteriorate the system performance depending on given threshold parameters. In this paper, we propose a novel DLPL scheme, called SDL (Sequential hypothesis testing based Dynamic LPL), which employs sequential hypothesis testing to decide whether to change the polling interval conforming to various traffic conditions. Simulation results show that SDL achieves substantial power saving over state-of-the-art DLPL schemes.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.7
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• pp.787-792
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• 2015

In this paper, We described the implementation of the Smart Gateway for heterogeneous interface integrated, Web Server and Building Energy Management System(: BEMS). The proposed system introduces the reduction of peak power and electric power usage with service model and operating algorithm for energy saving in building.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.17-18
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• 2000

A low-power source driver for TFT-LCDs has been proposed using the triple charge sharing method that enhances the AC power saving efficiency of the prior charge sharing method. The AC power saving efficiency of the proposed source driver reaches 66.6%. In addition, a novel OP-AMP with low-quiescent current has been developed. The measured quiescent current of the OP-AMP is $5{\mu}A{\sim}7{\mu}A$ at VDD=5V and VSS=0V with load resistance of $2k{\Omega}$ and load capacitance of 300pF.

• Journal of Drive and Control
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• v.14 no.3
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• pp.1-7
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• 2017

Energy consumption of conventional hydraulic excavators controlled by MCV is considerable when negative load is applied because the meter orifice and meter-out orifice are machined in one spool. Therefore, IMV is introduced to save energy use of hydraulic excavators, but existing hydraulic excavators have various advantages so it is difficult to make a clear comparison. In this study, we compare the use of an existing MCV excavator that has many advantages such as negative control, and IMV for boom up and down operation, and if IMV is used to save energy, we will examine the cause. If possible, for comparability under the same conditions, both systems use pressure balance valves to minimize power consumption when not using power in the actuator. The orifice area at each notch of each valve is calculated, and energy saving is verified by comparing the two systems through simulation.

• Journal of Integrative Natural Science
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• v.12 no.1
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• pp.20-23
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• 2019

Demand response is usually operated through using the power rates and incentives. Demand management based on power charges is the most rational and efficient demand management method, and such methods include rolling base charges with peak time, sliding scaling charges depending on time, sliding scaling charges depending on seasons, and nighttime power charges. Search for other methods to stimulate resources on demand by actively deriving the demand reaction of loads to increase the energy efficiency of loads. In this paper, ESS algorithm for saving energy based on predicting the amount of solar power generation that can be used for buildings with small loads not under electrical grid.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.365-372
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• 2014

In this paper, We implement a power-saving and efficient measures in buildings using the smart-meter. In order to save electric power energy, We propose an improved automatic power-factor controller(APFC) and demand control measures. This is achieved by controlling directly circuit breakers and the capacitor bank feeders in real time via a two-way smart-meter's ICT skills. Improved APFC is minimizing installation costs by series-parallel connecting heterologous capacitors to form a more diverse capacitor banking and controlling using the smart-meter. In order to suppress the demand power, We have designed a smart-meter with communication functions using Atmel's AVR465 and tested an operated lodging building for 24-hours. As a result, We made sure to always retained more than 95% power factor and did not occur over compensation.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.283-292
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• 2013

In order to ensure high performance, all the servers in an existing server cluster are always On regardless of number of real-time requests. They ensure QoS, but waste server power if some of them are idle. To save energy consumed by servers, the server power mode control was developed by shutdowning a server when a server is not needed. There are two types of server power mode control depending on when a server is actually turned off if the server is selected to be off: static or dynamic. In a static mode, the server power is actually turned off after a fixed time delay from the time of the server selection. In a dynamic mode, server power is actually turned off if all the services served in the server are done. This corresponds to a turn off after a variable time delay. The static mdoe has disadvantages. It takes much time to find an optimal shutdown time manually through repeated experiments. In this paper, we propose a dynamic shutdown method to overcome the disadvantages of static shutdown. The proposed method allows to guarantee user QoS with good power-saving because it automatically approaches an optimal shutdown time. We performed experiments using 30 PCs cluster. Experimental results show that the proposed dynamic shutdown method is almost same as the best static shutdown in terms of power saving, but better than the best static shutdown in terms of QoS.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.393-402
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• 2014

We have experienced an explosive increase of the IoT(Internet of Things) technology based devices including smart phones and the wireless communications. Also the growing power consumption in IEEE 802.11 WLANs(Wireless LANs) driven by these dramatic increases in not only mobile users and but also wireless APs(Access Points). To reduce the power consumption, this paper proposes a wireless AP power saving algorithm, which minimizes the transmission power without decrease the transmission and carrier sense ranges. A wireless AP which is use in our algorithm checks its own original coverage periodically for whether there is a new STA(Station) or not when its transmission power is decreased. Moreover, if there are no signaling message to connect the wireless AP, it changes its operation mode Wake-up to sleep. A Result shows that the proposed AP algorithm can reduce the total power consumption of the wireless AP approximated 18% and 35% compared to the conventional wireless AP with and without the existing power saving algorithm, respectively.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1339-1342
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• 2005

This paper presents a simple AC-DC power conditioner for a squirell-cage induction generator(IG) operating under variable shaft speeds. The necessary reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM power converter size. A simple control compensating for changes in the electrical loads as well as the variation in speed was developed to regulate the voltages of the IG system by controlling the rotor flux through its reactive and active currents control implementation. This proposed power conditioning scheme can be used efficiently as a wind power generation system where the output voltage of the IG is maintained constant voltage despite the variable frequency and the DC bus voltage of the PWM converter can be used for either DC applications such as battery charging or AC power applications with 60/50 Hz by connecting a stand alone inverter. The experimental and simulated operating performance results of a 5 kW IG scheme at various speeds and leads are presented.