• Journal of Digital Convergence
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• v.12 no.2
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• pp.271-276
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• 2014

The life-time and performance of a wireless sensor network is closely related to energy-efficiency of sensor nodes. In this paper, to increase energy-efficiency, each sensor node operates in one of three operational modes which are normal, power-saving, and inactive. In normal mode sensor nodes sense and transmit data with normal period, whereas sensor nodes in power-saving mode have three-times longer period. In inactive mode, sensor nodes do not sense and transmit any data, which makes the energy consumption to be minimized. Plus, the proposed algorithm can avoid unnecessary energy consumption by preventing transmitting duplicate sensed data. We implemented and simulated the proposed algorithm using Tiny OS based ZigbeX platfom and NS-2, respectively. Performance evaluation results show that the proposed algorithm can prolong sensor networks' lifespan by efficiently reducing energy consumption and its standard deviation of all sensor nodes.

• Electronics and Telecommunications Trends
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• v.38 no.2
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• pp.26-35
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• 2023

Energy efficiency is an important factor toward sustainable future mobile network systems. As the size of the 5G mobile network system increases, the consumption and costs of energy increase. Accordingly, energy-saving optimization has become a major process in network systems, and various related technologies for energy saving are being developed. We provide a brief review of the technical trends in energy saving in 3GPP 5G & 5G Advanced systems and O-RAN systems. We focus on power models and energy-saving technologies in various resource domains of 3GPP 5G & 5G Advanced systems and energy-saving use cases of O-RAN systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.317-326
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• 2012

Recently, many researchers have studied to solve the energy consumption of network equipments since the interest of Green IT has been increased. In this paper, we apply Low Power Idle (LPI) to OBS network to reduce energy consumption of network devices. Many previous researches have focused on maximizing the sleep time of network equipments to increase the energy saving efficiency of LPI. But transition overhead caused by LPI might not only depreciate the performance of energy saving but also increase packet delay. In this paper, Transition Decision (TD) algorithm is proposed to improve energy saving efficiency by reducing the number of unnecessary transition and guarantee the required QoS such as packet delay. To evaluate the performance of proposed algorithm, we model OBS edge router with LPI by OPNET and analyze the performance of the proposed algorithm in views of energy saving, transition count and average packet delay.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.741-748
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• 2005

Power saving module which is consisted of ferroelectric ceramic capacitor and time delay switching circuit was installed into electronic ballast in order to enhance energy efficacy and extend life time of fluorescent lamp. The impedance matching of negative resistance characteristics of F/L was optimized with the characteristics of ferroelectric ceramics capacitor to increase the light efficiency of the electronic ballast. The high efficiency of the electronic ballast was achieved by minimizing wasted power at the filament of F/L during the lighting by using the switching function of time delay circuit from preheating mode to non-preheating mode. The life time of F/L was also extended by eliminating the reverse electromotive force using time delay circuits to minimize the impacts to the filament of F/L from unwanted high voltage peaks during light-up period. As the results, the electronic ballast with the first grade energy efficiency was developed using ferroelectric ceramics and time delay module.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.603-608
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• 2015

The hybrid desiccant dehumidifier is an energy-effective system in comparison with the existing desiccant dehumidifier. Its main feature is to use the heat given off by the condenser as the react heat source. Through analysis of the elements for a more efficient design of the hybrid desiccant dehumidifier, it is evident that those energy-saving components do not work individually, but organically influence the efficiency of the equipment. Therefore, the hybrid desiccant dehumidifier may be an important product in the dehumidification industry.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.728-730
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• 1993

This paper describes a simple but effective V/F control method for energy saving of a special-purpose Induction motor driven by PWM inverter. The proposed method is based on efficiency control with no speed sensor that the V/F patterns could be changed to load variations. The experimental results shows great improvement of both efficiency and power factor and usefulness of the method.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3027-3031
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• 2011

In this study, By the time that TTX technology is adopted as railway rolling stock, we analyzed quantitatively energy saving by reducing the power consumption with the reduction of the operation time through the speed improvement and suggested the necessity to introduce TTX technology in the domestic rail vehicles. The effect of energy saving by comparing and analyzing the power consumption during the operation by TTX Hanvit 200 and 8200 electric locomotives to pull trains on the same line was suggested and the efficiency of the main devices(i.e C/I) of Hanvit 200 was compared and analyzed by measuring the power consumption by a single unit. For improving KORAIL management environment, reducing energy usage is an urgent challenge, its measures for solving them are constantly considered in many areas. In addition, at the time of improving the conventional track to speed up and changing the signals, Tilting technology will be contributed to the management environment by enlarging the passengers' demand through the reduction of the operation time and saving energy using the existing infrastructure.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.202-207
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• 2014

Recently, the study of energy saving technology of ships begins in earnest, as energy saving policies are performed all around the world. SEMS (Ship Energy Management System) is one of the techniques to increase energy efficiency by applying to a independent system like a ship and offshore. SEMS is composed of Cooling Pump Control System (CPCS), Renewable Energy Emergency Power Control System (REEPCS), Load Control System (LCS), and Heating, Ventilation, and Air Conditioning System (HVACS). SEMS is enable to increase energy efficiency and achieve integrated management through the interlocking of each system. Especially, it is possible to improve the flexibility of the selection of the generator capacity in conjunction with a rechargeable battery and renewable energy. In this paper, SEMS applied rechargeable battery is proposed and simulated. By applying the rechargeable battery, it was confirmed that SEMS applied rechargeable battery can be operated at optimum efficiency of the generator.

• Journal of Drive and Control
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• v.3 no.2
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• pp.8-13
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• 2006

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2218-2229
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• 2015

Recently Wi-Fi Alliance defined Wi-Fi direct, which can communicate through a direct connection between the mobile device anytime, anywhere. In Wi-Fi direct, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi direct standard defines two power management schemes: Opportunistic power saving scheme and Notice Of Absence (NOA) scheme. But, these two schemes do not consider the traffic pattern, so we cannot expect high energy efficiency. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi direct power saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the length of awake interval dynamically. Also, considering the inter-dependency among video frames, the proposed algorithm assigns priorities to video frames and ensures that a video frame with high priority is transmitted with higher probability than other frames with low priority. Simulation results shows that the proposed method outperforms the traditional NOA in terms with average delay and energy efficiency.