• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.71-78
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• 2015

Since most education organizations such as Universities have a plenty of PCs, much electric power can be wasted if their power states are not managed properly. This paper introduces the RPM(Remote Power Management) software system implemented to reduce a waste of PC power in Universities. The System manager can monitor power state of all PCs in a University and turn off PCs or change power states of PCs to low power states. The RPM consists of three software modules. First, Power Controller, which is installed in each user PC, saves the power by changing low power state by utilizing low power algorithm proposed in this paper. Also it reports power state of its PC to Power Server on the state changed. Second, Power Server module gathers power state information of all PCs, stores them in a DB, and sends all or some parts of the information to Power Viewer whenever the manager asks. The manager can turn off or change a certain PC to low power state. We evaluated the performance of power saving for the RPM and the result showed achievement of 40% power saving.

• Korean Journal of Acupuncture
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• v.27 no.2
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• pp.141-157
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• 2010

Objectives : The aim of this study is to examine the effects of acupuncture at PC7(Daereung) on normal human EEG using power spectral analysis. Methods : EEG power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 30 subjects (16 males and 14 females; averaged age = 23.4 years) were engaged with thirty channel EEG study. Results : In $\alpha$(alpha) band, the power values at Fp1, Fp2, F7, F8 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased. In $\beta$(beta) band, the power values at Fp1, Fp2 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased and at F8, TCP2 channels(p<0.05) during non-acupoint treatment were increased. In $\theta$(theta) band, the power values at Fp1, Fp2, F7, F8 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased. In $\delta$(delta) band, the power values at Fp1, Fp2, F7, Fz, F8 channels (p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel (p<0.05) during non-acupoint treatment was significantly decreased. $\alpha/\beta$ values during PC7 treatment were decreased. $\beta/\theta$ values during PC7 treatment were decreased. Conclusion : These results suggest that acupuncture at PC7 induce the change on $\alpha$(alpha), $\beta$(beta), $\theta$ (theta), $\delta$(delta) wave values being decreased and and bothe $\alpha/\beta$ and $\beta/\theta$ values being decreased respectively. This is considered that acupuncture at PC7 affects the activity of cerebral cortex and endocrine system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2171-2176
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• 2012

PCs and its peripherals uses more power in standby mode even if they are not actually being used. In particular, PCs and its peripherals used in school and office, plugged in at all times during working hours, but not used much time, even if turned off consume a portion of the power. In this paper, we developed Networked Smart Plug for Power Management of PC & Peripherals which is consist of EMS, Smart Plug, PC Agent and Smart Phone App. for power saving of PC and a variety of peripheral devices in office or home, and evaluated the performance of the system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.49-57
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• 2013

Power-saving PC software enables the inexpensive power control, but the installation of the power-saving software in all computers in the organization is not an easy task. Computer users in the organization are usually not cooperative as they do not think the power-saving cost is directly related to themselves. The PC power-saving system provides advantage to driving active participation in which users installs the power saving software by restricting IP address through the power management server. However, the problem with this approach is the security vulnerability to IP spoofing attacks, therefore we need to solve the problem that disrupt the entire network system rather than saving electric power. This paper proposes the security authentication system that can implement the efficiency saving power by providing high security for the members' computer system of the public institutions based on the PC power-saving system. Also, by analyzing it in comparison with other method, it is possible to check that the prospects of safety and efficiency are strengthened.

• Korean Journal of Acupuncture
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• v.24 no.2
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• pp.193-216
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• 2007

Objectives : The aim of this study was to examine the effect of electroacupuncture (EA) at the PC8 on normal human beings by using power spectral analysis. Methods : EEG (Electroencephalogram) power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 32 channels EEG study was carried out in 20 subjects (20 males; age=26.8 years old). Results : In ${\alpha}(alpha)$ band, the power values at F7, F8, P3 channels(p<0.05) during the $PC_8-acupoint$ treatment significantly decreased. In ${\beta}(beta)$ band, the power values at F4, F8, P3 channels(P<0.05) during the PC8-acupoint treatment significantly decreased. In ${\delta}(delta)$ band, the power values at F7, F8, P3 Po2 channels(p<0.05) during the $PC_8-acupoint$ treatment significantly decreased. In ${\theta}(theta)$ band, the power values at F7, Fz, F4 F8, FTC1, FTC2, CP2, TT2, P3, Pz, Po2 channels(p<0.05) during the PC8-acupoint treatment significantly decreased. Conclusions : This results suggest that Electroacupuncture at the PC8 mostly affect the change on theta(11 channels) bands.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.211-219
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• 2014

This paper proposes a low voltage high current LLC resonant converter for Green PC. Green PC is composed of a lot of blade PCs, and it is a centralized system to manage them in computer center. Green PC should require that its power supplies have several characteristics such as low output voltage, high output current, and high power conversion efficiency. Conventional PSFB (Phase Shift Full Bridge) converter is usually used as DC/DC converter for computer power supply because it has high power conversion efficiency thanks to ZVS (Zero Voltage Switching) operation under middle and high load conditions. However, this converter has some problems such as large switching noise and limitation of ZVS operation under light load condition. In order to improve the performance of power supply for Green PC, a new power supply using popular high efficiency LLC resonant converter for low voltage and high current application is proposed in this paper. The proposed power supply has ZVS capability over the entire load range, thus resulting in good efficiency and high switching frequency. Experimental results verify the performance of the proposed power supply for Green PC using 2[kW] (19[V], 105[A]) rated prototype converter.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1348-1357
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• 2015

Under traditional unified power quality conditioner (UPQC) control, a UPQC series converter (SC) is mainly used to handle grid-side power quality problems while its parallel converter (PC) is mainly used to handle load-side power quality problems. The SC and PC are relatively independent. The SC is usually in standby mode and it only runs when the grid voltage abruptly changes. In this paper, novel UPQC coordinated control strategies are proposed which use the SC to share the reactive power compensation function of the PC especially without grid-side power quality problems. However, in some cases, there will be a circulating current between the SC and the PC, which will probably influence the compensation fashion, the compensation capacity, or the normal work of the UPQC. Through an active power circulation analysis, strategies with and without a circulating current are presented which fuses the reactive power allocation strategy of the SC and the PC, the composite control strategy of the SC and the compensation strategy of the DC storage unit. Both of the strategies effectively solve the SC long term idle problem, limit the influence of the circulating current, optimize all of the UPQC units and reduce the production cost. An analysis, along with simulation andexperimental results, is presented to verify the feasibility and effectiveness of the proposed control strategies.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.317-321
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• 2021

As the large-scale renewable energy power plant increases, the high-capacity and compact Energy Storage System (ESS) is required. However, this trend could reduce the insulation reliability of ESS. In this study, the surface flashover characteristics for four types of solid insulators are investigated in the uniform electric field with AC and Lightning Impulse (LI) voltage waveforms under various contamination levels. In addtion, insulator surfaces are compared based on the contact angle before and after surface flashover. The experimental results show that AC flashover voltage is dependent on the materials and the contamination level, but LI flashover voltage is only associated with the contamination level. Especially, AC flashover voltage of PC (PolyCarbonate) is higher than that of other insulators, which is associated with the unique and sequential creepage discharge propagation pattern of PC. The localized discharges on the surface of PC form corresponding tracking points. Then, the interconnected trackings result in the complete flashover. This flashover patterns degrade the surface of PC much more than that of epoxy and Bulk Molding Compoud (BMC). Thus, the contact angle of PC is significantly reduced compared to that of other insulators. The increased hydrophilicity in the surface of PC enhances the insulator surface conductivity.

• Proceedings of the Korea Database Society Conference
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• 2010.06a
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• pp.33-41
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• 2010

Recently the number of IT equipment have increased. It consumes large amounts of energy and is emissions of greenhouse gases. Co2 emissions with the PC and the monitor has the highest percentage to 39% more than other IT equipment. In addition, Plan for your PC's power management and technology development is being pursued in developed countries. To reduce energy costs of organizations with large numbers of the PC and to cut down on Co2 emissions, the energy load control technology of ACPI standards-based PC IS suggested. AMI-based PC power-management system was constructed, Approximately 20% of operating a result of the test power consumption was reduced. Looking at the case of the United States, PC monitors from the University of Wisconsin-Oshkosh was Sleep mode. As a result, the monitor on a, $ 20 for a year reduced energy costs. In GE(General Electronic), Approximately 75,000 PC's power setting time was Monitor Off :15 minutes/ Hard Drives Off 30 minutes/ System Standby 30 minutes/ Hibernation mode 2 hours. 1 year, electric bill was $ 2.5 million savings and 3 years electric bill was $ 6.5 million savings. Measuring energy usage data, using the measured data, electric energy management technology is not. Platform development to measure energy usage for Individual energy-consuming equipment is urgently required.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.4
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• pp.307-316
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• 2001

In this paper, the multiple output forward converter forPC power supply with weighted voltage mode control which improves the characteristics of DC and transient responses is analyzed and designed. The power stage model of this converter including all the major parasitic components is derived and the small signal model is also derived. Determination of the weighting factors and a design procedure for the loop compensation are presented. Finally, the proposed controller is verified through the simulation of three output forward converter with SABER, and the experiment.