• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2479-2484
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• 2018

The filter bank multicarrier modulation (FBMC) technique is one of multicarrier modulation technique (MCM), which is mainly used to improve channel capacity of cognitive radio (CR) network and frequency spectrum access technique. The existing FBMC System contains serial to parallel converter, normal QAM modulation, Radix2 inverse FFT, parallel to serial converter and poly phase filter. It needs high area, delay and power consumption. To further reduce the area, delay and power of FBMC structure, a new clock gating technique is applied in the QAM modulation, radix2 multipath delay commutator (R2MDC) based inverse FFT and unified addition and subtraction (UAS) based FIR filter with parallel asynchronous self time adder (PASTA). The clock gating technique is mainly used to reduce the unwanted clock switching activity. The clock gating is nothing but clock signal of flip-flops is controlled by gate (i.e.) AND gate. Hence speed is high and power consumption is low. The comparison between existing QAM and proposed QAM with clock gating technique is carried out to analyze the results. Conversely, the proposed inverse R2MDC FFT with clock gating technique is compared with the existing radix2 inverse FFT. Also the comparison between existing poly phase filter and proposed UAS based FIR filter with PASTA adder is carried out to analyze the performance, area and power consumption individually. The proposed FBMC with clock gating technique offers low power and high speed than the existing FBMC structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권4호
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• pp.1797-1805
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• 2012

In this paper, Power LED(Light Emitting Diodes) is studied to driver as a new lighting system in the spotlight, replacing a large existing lighting system with fluorescent and incandescent lighting. To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Converter's switching frequency is 50[kHz], the first Duty Rate was made to increase gradually depending on the value of the detection were, 10[%] in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5[%] or less as the error was approximated. So, when input 15[V] were offered, a stable output 24[V] were obtained, and Dimming Control through the adjustment of brightness and current consumption were obtained to possible result.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제47권11호
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• pp.65-71
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• 2010

This paper presents a 14-band LO generator architecture for MB-OFDM UWB systems using 3.1 GHz~10.6 GHz frequency band. The proposed LO generator architecture has been consisted of only one PLL and the fewest nonlinear components to generate 14 LO signals with high purity while consuming low dc power consumption. In addition, major spurious generated from the LO generator have been located in the out of UWB band. The proposed LO generator has been implemented in a $0.13-{\mu}m$ CMOS technology and consumes a dc power consumption of 93~103 mW from a 1.5 V supply. The simulation results show an in-band spurious suppression ratio of more than 41 dBc and a band-switching time of below 3 nsec.

• Journal of Communications and Networks
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• 제10권2호
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• pp.137-147
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• 2008

This paper proposes a novel approach to interference avoidance via inter-cell relaying in cellular OFDMA-TDD (orthogonal frequency division multiple access - time division duplex) systems. The proposed scheme, termed asymmetry balancing, is targeted towards next-generation cellular wireless systems which are envisaged to have ad hoc and multi-hop capabilities. Asymmetry balancing resolves the detrimental base station (BS)-to-BS interference problem inherent to TDD networks by synchronizing the TDD switching points (SPs) across cells. In order to maintain the flexibility of TDD in serving the asymmetry demands of individual cells, inter-cell relaying is employed. Mobile stations (MSs) in a cell which has a shortage of uplink (UL) resources and spare downlink (DL) resources use free DL resources to off-load UL traffic to cooperating MSs in a neighboring cell using ad hoc communication. In an analogous fashion DL traffic can be balanced. The purpose of this paper is to introduce the asymmetry balancing concept by considering a seven-cell cluster and a single overloaded cell in the center. A mathematical model is developed to quantify the envisaged gains in using asymmetry balancing and is verified via Monte Carlo simulations. It is demonstrated that asymmetry balancing offers great flexibility in UL-DL resource allocation. In addition, results show that a spectral efficiency improvement of more than 100% can be obtained with respect to a case where the TDD SPs are adapted to the cell-specific demands.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제45권5호
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• pp.44-51
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• 2008

UV lamp systems have been used for cleaning of display panels of TFT LCD or Plasma Display Panel (PDP). However, the needs for high efficient cleaning and low cost made high voltage plasma cleaning techniques to be developed and to be improved. Dielectric-Barrier Discharges (DBDs), also referred to as barrier discharges or silent discharges have been exclusively related to ozone generation for a long time. In this paper, a 6kW high voltage plasma power supply system was developed for LCD cleaning. The 3-phase input voltage is rectified and then inverter system is used to make a high frequency pulse train, which is rectified after passing through a high-power transformer. Finally, hi-directional high voltage pulse switching circuits are used to generate the high voltage plasma. Some experimental results showed the usefulness of atmospheric plasma for LCD panel cleaning.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제27권1호
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• pp.1-7
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• 2016

In this paper, the tunable filter based on high power cavity using mechanical switch for 1.5 GHz band is presented. The LPF is inserted to eliminate the spurious wave, coupler is embeded to extract the output power, and then the tunable filter system is configured using mechanical switch. The LPF obtains attenuation over 40 dB between 4 GHz and 12.75 GHz, Coupler is satisfied with coupling value 40 dB and coupling isolation over 55 dB. The tunable filter system using mechanical switch obtains insertion loss 0.88 dB at bypass mode between 1,495.9 MHz and 1,510. 9 MHz, 3.29 dB at fil mode between 1,495.9 MHz and 1,500.9 MHz. It is also satisfied with output power of 132 W at the center frequency 1,498.4 MHz, and switching time below 10 ms.

• Proceedings of the KIEE Conference
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.212-214
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• 2004

In this study, we fabricated the organic thin film by self-assembly method by using nitro-group and methoxy-group organic molecule. Also, we selected the organic single molecule in organic thin film and measured current-voltage characteristics by using scanning tunneling microscopy. The Organic molecules that use in an experiment is 4,4'-(diethynylphenyl)-2'-nitro-1-benzen ethiol and 4-[2,5-dimethoxy-4-ph enylethynylphenyl]ethynylphenylethanthiol. 4,4'-(dimet hynylphenyl)-2'-nitro-1-benzenethiol is applied widely in molecular electronic device and 4-[2,5-dime thoxy-4-phenylethynylphenyl]ethynylphenylethanthiol composed in Korea Research Institute of Chemical Technology. To be confirmed the formation of the self-assembled monolayers, we observed the real time frequency shift of the QCM and investigated surface of the self-assembled monolayers the using STM. With this, we measured current to the organic single molecule, in condition of the air state. As a result, we confirmed in constant voltage that properties of negative differential resistance. Using properties of negative differential resistance to get from this study, application is expected to be molecular switching device, memory device and logic device.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제36권2호
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• pp.143-150
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• 2023

Underwater wireless communication is a challenging issue for realizing the smart aqua-farm and various marine activities for exploring the ocean and environmental monitoring. In comparison to acoustic and radio frequency technologies, the visible light communication is the most promising method to transmit data with a higher speed in complex underwater environments. To send data at a speedier rate, high-performance photodetectors are essentially required to receive blue and/or cyan-blue light that are transmitted from the light sources in a light-fidelity (Li-Fi) system. Here, we fabricated high-performance organic phototransistors (OPTs) based on P-type donor polymer (PTO2) and N-type acceptor small molecule (IT-4F) blend semiconductors. Bulk-heterojunction (BHJ) PTO2:IT-4F photo-active layer has a broad absorption spectrum in the range of 450~550 nm wavelength. Solution-processed OPTs showed a high photo-responsivity >1,000 mA/W, a large photo-sensitivity >10³, a fast response time, and reproducible light-On/Off switching characteristics even under a weak incident light. BHJ organic semiconductors absorbed photons and generated excitons, and efficiently dissociated to electron and hole carriers at the donor-acceptor interface. Printed and flexible OPTs can be widely used as Li-Fi receivers and image sensors for underwater communication and underwater internet of things (UIoTs).

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제44권5호
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• pp.62-70
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• 2007

In this paper, the boost Power Factor Correction(PFC) technique for Direct Torque Control(DTC) of brushless DC motor drive in the constant torque region is implemented on a TMS320F2812DSP. Unlike conventional six-step PWM current control, by properly selecting the inverter voltage space vectors of the two-phase conduction mode from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained, therefore a much faster torque response is achieved compared to conventional current control. Furthermore, to eliminate the low-frequency torque oscillations caused by the non-ideal trapezoidal shape of the actual back-EMF waveform of the BLDC motor, a pre-stored back-EMF versus position look-up table is designed. The duty cycle of the boost converter is determined by a control algorithm based on the input voltage, output voltage which is the dc-link of the BLDC motor drive, and inductor current using average current control method with input voltage feed-forward compensation during each sampling period of the drive system. With the emergence of high-speed digital signal processors(DSPs), both PFC and simple DTC algorithms can be executed during a single sampling period of the BLDC motor drive. In the proposed method, since no PWM algorithm is required for DTC or BLDC motor drive, only one PWM output for the boost converter with 80 kHz switching frequency is used in a TMS320F2812 DSP. The validity and effectiveness of the proposed DTC of BLDC motor drive scheme with PFC are verified through the experimental results. The test results verify that the proposed PFC for DTC of BLDC motor drive improves power factor considerably from 0.77 to as close as 0.9997 with and without load conditions.

• Journal of KIISE:Computer Systems and Theory
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• 제34권8호
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• pp.367-376
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• 2007

In this paper, we introduce an application-specific and adaptive power management technique for portable systems that support dynamic voltage scaling (DVS). We exploit both the idle time of multitasking systems running soft real-time tasks as well as memory- or CPU-bound code regions. Detailed power and execution time profiles guide an adaptive power manager (APM) that is linked to the operating system. A post-pass optimizer marks candidate regions for DVS by inserting calls to the APM. At runtime, the APM monitors the CPU's performance counters to dynamically determine the affinity of the each marked region. for each region, the APM computes the optimal voltage and frequency setting in terms of energy consumption and switches the CPU to that setting during the execution of the region. Idle time is exploited by monitoring system idle time and switching to the energy-wise most economical setting without prolonging execution. We show that our method is most effective for periodic workloads such as video or audio decoding. We have implemented our method in a multitasking operating system (Microsoft Windows CE) running on an Intel XScale-processor. We achieved up to 9% of total system power savings over the standard power management policy that puts the CPU in a low Power mode during idle periods.