• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1219-1228
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• 1991

In the actual case, a model of noise canceller using adaptive filter has both a channel transfer function from noise source to main signal input and to noise canceller input. The previous models of noise canceller have been considered to be only one side channel transfer function. Therefore, it is proposed that a new model has two channel transfer functions and derives an optimal tranfer function of adaptive noise canceller. The adaptive filter is using the joint process lattice filter that has fast adaptive speed. The signal noise radio has been improved by a model of ANC-ALE and it is confirmed with computer simulation. Beside, a dc bias is very effective for noise cancelling, especially to the particular signal.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1078-1087
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• 2020

The current study was carried out to investigate the effect of oral administration for 30 days of the Jijang kimchi extracts on prevention of diabetes, alcoholic liver injury and reduction of blood lipids in laboratory rats with alcoholic liver injury and diabetes induced by streptozotocin. In a diabetic model animals, the blood lipid profile, ALT, and AST levels were lower in kimchi extract groups compared to DC (diabetes control) group, and blood glucose level of DCJK (DC+oral administration with Jijang kimchi extracts) group was lower than that of DCCK (DC+oral administration with commercial kimchi extracts) group. Insulin levels were increased in order of NC (normal control), DCJK > DCCK > DC groups. In alcoholic liver injury model animals, ALT, AST and bilirubin were lowed in order of AC (alcohol group received 1 bottle of soju) > ACCK (1 bottle of soju plus oral administration with commercial kimchi extracts) ACJK (AC plus oral administration with Jijang kimchi extracts) > NC groups. In the clinical pathologic findings of liver tissue, AC group was severely injured, and tended to be improved in groups eating a 1 bottle of soju plus oral administration with kimchi extracts, especially Jijang kimchi extract group. The results suggest that eating Jijang kimchi can improve insulin secretion ability while lowering blood lipid profile, blood sugar and ALT, AST, and bilirubin levles in diabetic and alcoholic liver injury model animals.

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.63-73
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• 2011

Metamorphic HEMTs (MHEMTs) have emerged as excellent challenges for the design and fabrication of high-speed HEMTs for millimeter-wave applications. Some of improvements result from improved mobility and larger conduction band discontinuity in the channel, leading to more efficient modulation doping, better confinement, and better device performance compared with conventional pseudomorphic HEMTs (PHEMTs). For the optimized device design and development, we have performed the calibration on the DC characteristics of our fabricated 0.1 ${\mu}m$ ${\Gamma}$-gate MHEMT device having the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}$As heterostructure on the GaAs wafer using the hydrodynamic transport model of a commercial 2D ISE-DESSIS device simulator. The well-calibrated device simulation shows very good agreement with the DC characteristic of the 0.1 ${\mu}m$ ${\Gamma}$-gate MHEMT device. We expect that our calibration result can help design over-100-GHz MHEMT devices for better device performance.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1528-1538
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• 2018

In this paper, configuration of $1-{\phi}$ seven-level boost DC-link cascade based reversing voltage multilevel inverter (BDCLCRV MLI) is proposed for uninterrupted power supply (UPS) applications. It consists of three level boost converter, level generation unit and full bridge circuit for polarity generation. When compared with conventional boost cascaded H-bridge MLI configurations, the proposed system results in reduction of DC sources, reduced power switches and gate drive requirements. Inverter switching is accomplished by providing appropriate switching angles that is generated by any optimization switching angle techniques. Here, round modulation control (RMC) method is taken as the optimization method and switching angles are derived and the same is compared with various switching angles methods i.e., equal-phase (EP) method, and half-equal-phase (HEP) method which results in improved quality of obtained AC power with lowest total harmonic distortion (THD). Reduction in DC sources and switch count makes the system more cost effective. A simulation and prototype model of $1-{\phi}$ seven-level BDCLCRV MLI system is developed and its performance is analyzed for various operating conditions.

• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1975-1981
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• 2019

Recently, outbreaks of food-borne diseases linked to fresh produce have been an emerging public health concern worldwide. Previous research has shown that when human pathogens co-exist with plant pathogens, they have improved growth and survival rates. In this study, we have assessed whether Escherichia coli O157:H7 benefits from the existence of a phytopathogenic bacterium and the underlying mechanisms were further investigated. When Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and E. coli O157:H7 were co-inoculated by either dipping or infiltration methods, the populations of E. coli O157:H7 increased; however, no effect was observed when type three secretion system (T3SS) mutants were used instead, suggesting that E. coli O157:H7 benefits from the presence of Pst DC3000. In addition, this study confirmed that the E. coli O157:H7 populations increased when they occupied the tomato leaf intercellular space; this colonization of the interior of the leaves was possible due to the suppression of the PAMP-triggered immunity (PTI) by Pst DC3000, in particular with the AvrPto effector. In conclusion, our data support a plausible model that E. coli O157:H7 benefits from the presence of Pst DC3000 via AvrPto suppression of the PTI resistance.

• Journal of Power Electronics
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• v.8 no.1
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• pp.51-59
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• 2008

This paper addresses several issues concerning the analysis, design, modeling, simulation and development of single-phase, single-switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis and design is presented for single-switch topologies, namely forward buck, flyback, Cuk, Sepic and Zeta buck-boost converters, with high frequency isolation for discontinuous conduction modes (DCM) of operation. With an awareness of modem design trends towards improved performance, these switching converters are designed for low power rating and low output voltage, typically 20.25W with 13.5V in DCM operation. Laboratory prototypes of the proposed single-switch converters in DCM operation are developed and test results are presented to validate the proposed design and developed model of the system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1735-1740
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• 2009

This study presents a brushless DC (BLDC) motor for air management system of fuel cell modules. Magnetic equivalent circuit model and finite element analysis are used to design the motor, and an improved structure is considered to reduce a mechanical loss induced from bearing units. Finally, air blower system combined with the motor and an impeller is manufactured and output properties, such as an air pressure and an amount of flowing air, are measured. Through the experimental results, a validity of the simulated one is confirmed.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.1
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• pp.57-68
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• 1989

This paper treats the analytical and experimental studies on the improvement of commutating circuit for the speed control of DC motor. A simple circuit composed of R, L and C elements is proposed here for switching off power SCR carrying the load current. The real important in this chopper circuit is to determine the reasonable values of commutating circuit constants. In this paper, the reasonable values of the commutating circuit constants are basically determined on a view point of commutating performances in the given circuit model and must satisfy the following conditions. The first, the peak commutating current should be larger than the anticipated maximum load current. The second, the circuit turn-off time (tc) must be longer than the SCR turn-off time (tq). The third, the resistor should be enough large to permit the current to be neglected in the analysis of the commutation circuit, as well as be enough small to permit to charge the capacity voltage (Ec) to the half the value of source voltage (E) before the next communication cycle is initiated. The last, the period of chopping signal must be the least possible multiple of the damping vibration period of commutating circuit. The improved chopper circuit used in the experiment under unloaded condition was composed to meet the reasonable conditions mentioned above, and a successful commuting performance was achieved without failure. Several types of microprocessor having a different value of CPU speed individually have been applied to the experiment under the loaded conditions. Also it shows that the faster the speed of CPU is, the more stable the commutation turns out.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.371-379
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• 2000

The 4-pole linear homopolar synchronous motor (LHSM), so called linear inductor motor, is composed of the figure-of-eight shaped 3-phase armature windings, DC field windings, and the segmented secondary with the transverse bar track. To reduce the calculation time, the simplified 3D finite element model with equivalent reluctance and/or permanent magnet is presented. To obtain a clear understanding, propriety and usefulness of the developed model, we compare with the results of simplified 3D FEA, general 3D FEA and test. Consequently, the results of simplified and 3D FEM analysis are nearly identical, but much larger than that of static test at d-axis armature excitation. Therefore the improved FEA model, such as full model with half slot, is needed for the precise analysis.