• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.152-161
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• 2007

IEEE 802.11 Wireless Local Area Network (WLAN) became a prevailing technology for the broadband wireless Internet access, and new applications such as Voice over WLAM (VoWLAN) are fast emerging today. For the battery-powered VoWLAN devices, the standby time extension is a key concern for the market acceptance while today's 802.11 is not optimized for such an operation. In this paper, we propose a novel Idle Mode operation, which comprises paging, idle handoff, and delayed handoff. Under the idle mode operation, a Mobile Host (MH) does not need to perform a handoff within a predefined Paging Area (PA). Only when the MH enters a new PA, an idle handoff is performed with a minimum level of signaling. Due to the absence of such an idle mode operation, both IP paging and Power Saving Mode (PSM) have been considered the alternatives so far even though they are not efficient approaches. We implement our proposed scheme in order to prove the feasibility. The implemented prototype demonstrates that the proposed scheme outperforms the legacy alternatives with respect to energy consumption, thus extending the standby time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.10
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• pp.930-936
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• 2014

Smart Multiple-Tap to be introduced in this paper, is an electronic device that controls the Multibple-Tap through the Smartphone. It runs on network and has an inbuilt Zigbee communication module. Thus, users can control home devices from remote through home server. Mentioned home server is operated as a gateway and is connected with smart devices on the Internet. To sum up, Users using this Smart Multiple-Tap can check the state information of the multi-tap ON/OFF and can control immediately by smartphone. also, Smart Multiple-Tap perfectly shut down the standby power. when users turn off each of the Smart Multiple-Tap's circle, It drives automatically lowest electricity-consuming mode and shut down the standby power by its own built-in SSR module. therefore, it will bring the energy saving effect on environment using Smart Multiple-Tap.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.63-72
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• 2005

This paper describes a new approach for the operating system level power management to reduce the energy consumed in the IO devices in a robot platform, which provides various functions such as navigation, multimedia application, and wireless communication. The policy proposed in the paper, which was named the Energy-Aware Job Schedule (EAJS), rearranges the jobs scattered so that the idle periods of the devices are clustered into a time period and the devices are shut down during their idle period. The EAJS selects a schedule that consumes the minimum energyamong the schedules that satisfy the buffer and time constraints. Note that the burst job execution needs a larger memory buffer and causes a longer time delay from generating the job request until to finishing it. A prototype of the EAJS is implemented on the Linux kernel that manages the robot system. The experiment results show that a maximum $44\%$ power saving on a DSP and a wireless LAN card can be obtained with the EAJS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1799-1807
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• 2016

In this paper, we propose the automatic demand response systems which reduce the electric power consumption for the period automatically distinct from the existing passive demand response that a subscriber directly controls the energy consumption. The proposed systems are based on SEP 2.0 and consist of the demand response management program, the demand response server, and the demand response client. The demand response program shows the current status of the electric power use to a subscriber and supports the function which the administrator enables to creates or cancels a demand response event. The demand response server transmits the demand response event received from the demand response management program to the demand response client through SEP 2.0 protocol, and it stores the metering data from the demand response client in a database. After extracting the data, such as the demand response the start time, the duration, the reduction level, the demand response client reduces the electric power consumption for the period.

• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.2
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• pp.15-24
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• 2013

This project is mainly related to evaluation of total energy consumption of low energy house, the exterior envelope of which was wholly composed of structural insulated panels(SIP). The U-value of applied SIP was in the range of 0.189 to $0.269W/m^2{\cdot}K$ and the U-value of pair glass from 0.78 to $1.298W/m^2{\cdot}K$ was applied for window dependent to its function respectively. For comparison of total energy performance, the energy simulation for pilot house was performed to compare with the control house having insulation criteria of Korean building regulation in 2009. Based on simulation of dynamic energy performance, the pilot house saved 48.3% of annual energy consumption while the control house in 2009 consumed as 85.7GJ/y. In case of heating, the result showed that the energy saving ratio amounted to 76.7%. For $CO_2$ emission, the pilot house diminished approximately 35.4% from $6,208.4kgCO_2$ to $4,009.2kgCO_2$. In payback period to early investment, it was analyzed the pilot house took 7.8 years, when the low energy house built by other insulation method with same thermal perfusion took 11.5 years. From this result, it is considered that the SIP is more effective, economic to Green Home application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.221-229
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• 2007

In this paper, we propose and analyze the optimized sleep mode for a mobile node (MN) in IEEE 802.16e wireless metropolitan area networks. Because a MN in a sleep mode specified in 802.16e specification should maintain state information with the base station currently attached, it must renew sleep state with a new base station after handover which leads to unnecessary waste of battery power. Noting that the mobility pattern of a MN is independent of call arrival patterns, we propose an optimized sleep mode to eliminate unnecessary standby period of a MN in sleep state after handover. We also propose an analytical model for the proposed scheme in terms of power consumption and the initial call response time. Simulation studies that compare the performance between the sleep mode and the optimized sleep mode show that our scheme marginally increases initial call response delay with the huge reduction in power consumption.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.4
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• pp.193-204
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• 2017

Various 3D-stacked DRAMs have been proposed to overcome the memory wall problem. Hybrid Memory Cube (HMC) is a true 3D-stacked DRAM with stacked DRAM layers on top of a logic layer. The logic die is mainly used to implement a memory controller for HMC, and it is connected through a high speed serial link called SerDes with a host that is either a processor or another HMC. In HMC, the serial link is crucial for both performance and power consumption. Therefore, it is important that the link is configured properly so that the required performance should be satisfied while the power consumption is minimized. In this paper, we propose a HMC system model included the high speed serial link to estimate performance accurately. Since the link modeling strictly follows the link flow control mechanism defined in the HMC spec, the actual HMC performance can be estimated accurately with respect to each link configuration. Various simulations are conducted in order to deduce the correlation between the HMC performance and the link configuration with regard to memory utilization. It is confirmed that there is a strong correlation between the achievable maximum performance of HMC and the link configuration in terms of both bandwidth and latency. Therefore, it is possible to find the best link configuration when the required HMC performance is known in advance, and finding the best configuration will lead to significant power saving while the performance requirement is satisfied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1901-1907
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• 2015

Today's smartphones and user devices are equipped with multiple radio interfaces increasingly. Aggregating theses multiple radio interfaces and using them concurrently will increase a user's communication speed immediately, but at the expense of increased power consumption. In this paper, we develop a mathematical performance model of an adaptive radio activation scheme by which a radio interface is activated only when needed for performance increase and deactivated otherwise. The developed model shows that the adaptive scheme reduces delay significantly and almost halves power consumption below a certain level of traffic input.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.245-250
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• 2017

Worldwide environmental regulations have been enhanced for emission reduction of greenhouse gases and air pollutants; accordingly, some measures were prepared. Furthermore, the need for effective and reasonable energy-saving methods is growing in accordance with that for environmental pollution minimization. In the case of marine engineering, techniques for the development of eco-friendly vessels have been actively studied, including reduction of exhaust gas emissions, development of alternative fuel, and development of a new propulsion system. In this study, we presented the basic concepts and analyzed the speed, current, voltage, and output power characteristics of each operating mode, i.e., operating mode of battery, generator, and full power.