• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.8
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• pp.679-686
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• 2013

Power efficiency becomes more important in wireless LANs as the mobile stations send more data with limited batteries. It has been known that the IEEE 802.11 PSM is not efficient in high load networks: AP cannot deliver buffered packets to a PS station immediately and it can lead the station to stay in active state quite long and result in energy waste. Moreover, it is inefficient that only one data frame is retrieved by a PS-POLL frame. In this paper, we propose a time slotted scheme to enhance the PSM, in which a mobile station can reserve time slots to receive data frames. Our mechanism can reduce collisions by reservation and decrease the channel occupancy by transmitting multiple data frames via one PS-POLL. The analytic model and simulation results show that proposed scheme reduces power consumption significantly and enhances the performance of PSM.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.526-531
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• 2009

Recently, many interests on the ubiquitous environment and the practical technologies associated with it have been significantly increasing along with the rapid development of wireless technologies. The development of the automated systems based on the ubiquitous environment is required as the concept of the term "ubiquitous" is integrated into the fields of existing IT. In this paper, we design and implement a power-saving management system using RFID/USN technologies. It efficiently manages the power consumption of the electronic machine such as electric lights, electric heaters, and air conditioners in a building. The proposed system controls the electronic machines and monitors their status by RFID and collects the real time information about the surroundings and power consumption of the electronic machines by USN. Especially, it analyzes the real time information and supports the intelligent scheduler with the best power-saving. Finally, this paper shows the difference between the proposed system and the existing systems and the reality of our system through the real time user interface about the power-saving management.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.1-6
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• 2019

In this paper, we have developed an app that can control IPTV - Miracast and the Internet with Android 7.0 on the embedded board. The app can be controlled by the remote control of IPTV and can receive TV when using IPTV. And Miracast and Embedded board are put into the power saving mode. When one mode is selected in this way, the other two modes enter the power saving mode and the power saving control technology is applied to reduce energy consumption. The board used in this paper was Android version 7.1.2 version of Raspberry pie 3B / B + and Asus Tinker board s, and Android Studio program was used to make the app and a synchronization control program was also developed to operate with IPTV remote control. The operation of the Android start program using the power saving power control technology and the remote control synchronization control program developed in this way is confirmed to be normal operation as a result of applying to the actual IPTV.

• Journal of Industrial Technology
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• v.35
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• pp.41-45
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• 2015

This paper presents a development of the ELB (Electronic Leakage Breaker) based on a reduction of standby power dissipation as with maintaining conventional performance. In order to minimize the standby power consumption of the conventional circuit, we analyze the cause of 0.3W dissipation of the circuit. By employing the TR-triggered circuit to secure the standby power of 0.10W after testing and evaluation while CRD inserted circuit showed the performance of 0.17W levels. Implementing SMPS IC and TNR device circuit was designed and showed of its power to less than 0.06W. Developed ELB is expected much standby power savings in large power distributor or heavy users.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.324-330
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• 2015

Energy Saving Methods in existing railway vehicle are considered by active approach such as regenerative energy storage and utilization, eco driving, etc. On the other hands, energy saving measures in railway station are operated by passive method such as reduction of operating time in ventilation system, cooing system and power equipment. To reduce energy and for independence in railway system, it requires an active energy saving measures. It needs to its own power source besides the power source of electric supply company such as renewable energy and regenerative energy and take the advantage of power storage system and stored power are used in optimum time. This paper deal with 3-level NPC inverter and T-type NPC inverter that used in various multi-level topology applicable to the railway system.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.7-12
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• 2007

It is strongly requested to reduce fuel consumption because of high oil price and exhaust gases of road vehicles for environmental preservation. To solve these problems, several types of hybrid vehicles have been developed. Among them, flywheel hybrid vehicle using variable displacement pump/motor was already proposed as one of the feasible hybrid systems in place of hybrid vehicle by the conventional storage battery. The proposed flywheel hybrid vehicle is to keep constant pressure of high pressure line by the control of swash plate angle of flywheel pump/motor as pressure compensator. The efficiency of the overall system depends severely on the efficiency of hydraulic pump/motor in the energy saving hydraulic control system by simulation. According to the control methods of swash plate angle of piston pump/motor, there remain several problems to be solved. In this paper, experimental setup for energy saving is fabricated and the efficiency of energy saving is investigated by experiments with respect to various experimental conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.10
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• pp.969-976
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• 2004

Building energy saving is one of the most important issues in these days. Energy saving control strategies should be developed properly to achieve the saving. One of such area we could apply is the HVAC (Heating, Ventilation and Air-Conditioning) system. Through the optimal control algorithm for building energy management system (EMS), you can not only save the cost of building energy, but also protect HVAC system components against the unexpected condition. In order to verify the effectiveness of building energy saving, field test was accomplished for several months at 'A' building. And to get the measured data, remote control was used. If the remote control is used in BAS (Building Automation System), control and monitoring can be done for all of the building systems, such as HVAC, power, lighting, security and fire-alarm etc. anywhere any time. Using the remote control, Control and monitoring is possible for the testing system without going there. As the results of field test, we could reduce $5{\sim}10\%$ of the building energy cost.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.370-371
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• 2006

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy Production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as ell as the analysis of energy saving effect. his paper presents he present state analysis of inverter DSM program and propose he improvement for activation of inverter DSM program.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.521-523
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• 2001

The electric demand increase, financial need for new power plant constructions and environmental problem have led to search for more efficient energy production and energy conservation technology. To minimize the construction of power plants and reduce total power consumption include installation of inverters to motors used for pumps and fans. However, the high price of Inverters is the biggest obstacle to their wide use. Accordingly, to maximize the effect of energy saving by the expanded use of inverters, governmental economic support as well as the analysis of energy saving effect. This paper presents the cost-effectiveness analysis for DSM program evaluation and case study to analyze inverter DSM program.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.781-784
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• 2005

This paper is aimed at presenting a proton exchange membrane ( PEM ) fuel cell stack. The fuel cell electrical output voltage and current (V-I) characteristic is described for the first time by a simplified closed form suitable. The characteristics obtained from the simulation are compared with the experimental results on a Ballard commercial fuel cell stack as well as to the manufacturer given data.