• Title/Summary/Keyword: Current Modulating

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Induction Heating PWM High Frequency Inverter using New Active Auxiliary Resonant Snubber

  • Mun, Sang-Pil;Kim, Chil-Ryong;Lee, Jong-Kurl;Kim, Hong-Sin;Jung, Sang-Hwa;Kwon, Soon-Kurl
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.3
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    • pp.40-51
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    • 2008
  • This research presents a new active auxiliary resonant snubber with for induction heating PWM high frequency inverter solving the problem of induction heating PWM high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the active auxiliary resonant snubber with for induction heating PWM high frequency inverter. The inverter circuit which is attempted by the on-off operation of a switch has the effect of reducing the power loss due to soft switching and high frequency switching. This confirms that power regulation is possible on a continuous basis from 0.25[kW] to 2.84[kW] where the duty factor(D) changes from 0.08 to 0.3 under zero current switching which operates by an asymmetrical pulse width modulating control. The power conversion efficiency is 95[%]. Due to these results, the active auxiliary resonant snubber for an induction heating PWM high frequency inverter is considered effective as a source of induction heating.

A study on Sinusoidal Phase Modulating interferometer using laser diode (레이저 다이오드를 이용한 정현적 위상변조 간섭계에 대한 연구)

  • Pyo K.Y.;Park N.G.;Lee G.Y.;Kang Y.J.;Kim K.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.926-929
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    • 2005
  • Recently, laser interferometer is widely used as a measuring system in many fields because of its high resolution and its ability to measure a board area in real-time ail at once. In conventional laser interferometer, for examples Out of plane ESPI, In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3-D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include noli-linear errors and limited time of use. In present study, a new type of laser interferometer using a laser diode(LD) is proposed. Using Laser Diode Sinusoidal Phase Modulating(LD-SPM) interferometer, the phase modulation can be directly modulated by controlling the LD injection current thereby eliminating the need for PZT components.

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Calcium-activated Ionic Currents in Smooth Muscle Cells from Rabbit Superior Mesenteric Artery

  • Lee, Moo-Yeol;Bang, Hyo-Weon;Uhm, Dae-Yong;Rhee, Sang-Don
    • The Korean Journal of Physiology
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    • v.28 no.2
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    • pp.151-157
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    • 1994
  • Intracellular free $Ca^{2+}$ contributes to regulation of various events occurring in vascular smooth muscle cells. One of these events is modulating the membrane iou currents. Single smooth muscle cells were isolated from rabbit mesenteric artery. Three kinds of $Ca^{2+}-activated\;current$ were studied with the patch clamp method. $Ca^{2+}-activated\;K^+\;current$ with a large oscillation was recorded in the depolarized potential range. The single channel conductance of this current was about 250 pS. It was abolished by replacing intracellular $K^+\;with\;Cs^+$. A $Ca^{2+}-activated$ nonselective cation current was observed in both the depolarized and hyperpolarized potential ranges. And it was blocked by replacement of extracellular $Na^+$ with N-methylglucamine (NMG) or extracellular application of $Cd^{2+}$. $Ca^{2+}-activated\;Cl^-\;current$ was revealed in the whole voltage range and was blocked by niflumic acid. These results indicate that at least three kinds of $Ca^{2+}-activated$ ionic currents exist in smooth muscle cells from rabbit superior mesenteric artery.

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A study on DSP based power analyzing and control system by analysis of 3-dimensional space current co-ordinates (3차원 전류좌표계 해석법에 의한 DSP 전력분석 제어장치에 관한 연구)

  • 임영철;정영국;나석환;최찬학;장영학;양승학
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.4
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    • pp.543-552
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    • 1996
  • The goal of this paper is to developed a DSP based power analyzing and control system by 3-Dimensional (3-D) space current co-ordinates. A developed system is made up of 486-PC and DSP (Digital Signal Processor) board, Active Power Filter, Non-linear thyristor load, and Power analyzing and control program for Windows. Power is analyzed using signal processing techniques based on the correlation between voltage and current waveforms. Since power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm, flexibility of the proposed system which has both power analysis mode and control mode, is greatly enhanced. Non-active power generated while speed of induction motor is controlled by modulating firing angle of thyristor converter, is compensated by Active Power Filter for verifying a developed system. Power analysis results, before/after compensation, are numerically obtained and evaluated. From these results, various graphic screens for time/frequency/3-D current co-ordinate system are displayed on PC. By real-time analysis of power using a developed system, power quality is evaluated, and compared with that of conventional current co-ordinate system. (author). refs., figs. tabs.

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Neuromodulation for Insomnia Management (불면증 치료법으로서의 뉴로모듈레이션)

  • Yoon, Ho-Kyoung
    • Sleep Medicine and Psychophysiology
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    • v.28 no.1
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    • pp.2-5
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    • 2021
  • Hyperarousal or increased brain excitability is thought to play a key role in the pathophysiology of insomnia. Neuromodulation techniques are emergent complementary therapies for insomnia and can improve sleep by modulating cortical excitability. A growing body of literature support the idea that neuromodulation can be effective in improving sleep or treating insomnia. Recent evidence has revealed that neuromodulation methods can improve objective and subjective sleep measures in individuals with insomnia, although effects vary according to protocol. Different mechanisms of action might explain the relative efficacy of neuromodulation techniques on sleep outcomes. Further research testing different stimulation parameters, replicating existing protocols, and adding standardized sleep-related outcomes could provide further evidence on the clinical utility of neuromodulation techniques.

Ginseng, a promising choice for SARS-COV-2: A mini review

  • Ratan, Zubair Ahmed;Mashrur, Fazla Rabbi;Runa, Nusrat Jahan;Kwon, Ki Woong;Hosseinzadeh, Hassan;Cho, Jae Youl
    • Journal of Ginseng Research
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    • v.46 no.2
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    • pp.183-187
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    • 2022
  • The current Covid-19 pandemic has changed the entire world and bought so many unprecedented challenges to the scientific community. More than 5 million people died due to the SARS-COV-2 outbreak. For many thousands of years, ginseng, the traditional herb has been used for various infectious diseases by traditional healers. Ginseng showed promising antiviral effects by modulating both natural and acquired immunity. Ginseng might be used as a potential therapeutic agent to prevent SARS-CoV-2 infection along with the vaccine. In this current review, we offer an alternative approach for SARS-COV-2 prevention during this unprecedented pandemic.

Character of Induction Heating ZCS PWM SEPP High Frequency Inverter (유도가열용 ZCS PWM SEPP 고주파 인버터의 특성)

  • Mun, Sang-Pil;Kim, Chil-Ryong;Kwak, Dong-Kurl;Kim, Choon-Sam;Nakaoka, Mutsuo
    • Proceedings of the KIPE Conference
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    • 2007.11a
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    • pp.133-135
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    • 2007
  • This research presented the new zero-current switching pulse width modulation SEPP(Single Ended Push-Pull)high frequency inverter for solving the problem of the zero-current SEPP high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the zero-current switching pulse width modulation SEPP high frequency inverter. The inverter circuit which is attempted by on-off operation of a switch has the reduction effect of the power loss due to a soft switching and a high frequency switching. And it confirmed that the power regulation is possible continuously from 0.25[kW] until 2.84[kW] in the case the duty rate(D) changes from 0.08 to 0.3 under zero-current switching operating by a dissymmetry pulse width modulating control and the power conversion efficiency comes true the efficiency of 95[%]. Due to the result above, the ZCS PWM SEPP high frequency inverter will be effective as sources of an induction heating apparatus.

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Soft Switching High Frequency Inverter for New Induction Heating (새로운 유도가열용 소프트 스위칭 고주파 인버터)

  • Kim, C.Y.;Mun, S.P.;Kim, M.Y.;Kim, H.J.;Lyu, J.Y.;Kim, S.W.
    • Proceedings of the KIEE Conference
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    • 2007.11c
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    • pp.119-124
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    • 2007
  • This research presented the new zero-current switching pulse width modulation SEPP(Single Ended Push-Pull)high frequency inverter for solving the problem of the zero-current SEPP high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the zero-current switching pulse width modulation SEPP high frequency inverter. The inverter circuit which is attempted by on-off operation of a switch has the reduction effect of the power loss due to a soft switching and a high frequency switching. And it confirmed that the power regulation is possible continuously from 0.25[kW] until 2.84[kW] in the case the duty rate(D) changes from 0.08 to 0.3 under zero-current switching operating by a dissymmetry pulse width modulating control and the power conversion efficiency comes true the efficiency of 95[%]. Due to the result above, the ZCS PWM SEPP high frequency inverter will be effective as sources of an induction heating apparatus.

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Induction Heating ZCS PWM SEPP High Frequency Inverter (유도가열용 ZCS PWM SEPP 고주파 인버터)

  • Mun, Sang-Pil;Gwon, Sun-Geol;Lee, Jong-Geol;Ju, Seok-Min;Gang, Sin-Chul
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.10a
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    • pp.241-243
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    • 2008
  • This research presented the new zero-current switching pulse width modulation SEPP(Single Ended Push-Full)high frequency inverter for solving the problem of the zero-current SEPP high frequency inverter circuit which is using widely in the practical application of an induction heating apparatus, the soft switching operation and power control are impossible when the lowest power supply in the zero-current switching pulse width modulation SEPP high frequency inverter. The inverter circuit which is attempted by on-off operation of a switch has the reduction effect of the power loss due to a soft switching and a high frequency switching. And it confirmed that the power regulation is possible continuously from 0.25[kW] until 2.84[kW] in the case the duty rate(D) changes from 0.08 to 0.3 under zero-current switching operating by a dissymmetry pulse width modulating control and the power conversion efficiency comes true the efficiency of 95[%]. Due to the result above, the ZCS PWM SEPP high frequency inverter will be effective as sources of an induction heating apparatus.

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Cortical Activation in the Human Brain induced by Transcranial Direct Current Stimulation (경두개 직류전류 자극이 대뇌피질의 뇌 활성도에 미치는 영향)

  • Kwon, Yong-Hyun;Kim, Chung-Sun;Jang, Sung-Ho
    • The Journal of Korean Physical Therapy
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    • v.21 no.4
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    • pp.73-79
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    • 2009
  • Purpose: Recently, neurostimulation studies involving manipulation of cortical excitability of the human brain have been increasingly attempted. We investigated whether transcranial direct current stimulation (tDCS) applied to the underlying cerebral cortex, directly induces cortical activation during fMRI scanning. Methods: We recently recruited five healthy subjects without a neurological or psychiatric history and who were right-handed, as verified by the modified Edinburg Handedness Inventory. fMRI was done while constant anodal tDCS was delivered to the underlying SM1 area?? immediately after the pre-stimulation for eighteen minutes. Results: Group analysis yielded an averaged map that showed that the SM1 area and the superior parietal cortex in the ipsilateral hemisphere were activated. The voxel size and peak intensity were, respectively, 82 and 5.22 in the SM1, and 85 and 5.77 in the superior parietal cortex. Conclusion: Cortical activation can be induced by constant anodal tDCS of the underlying motor cortex. This suggests that tDCS may be an effective therapeutic device for enhancing? physical motor function by modulating neural excitability of the motor cortex.

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