• Journal of Power Electronics
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• v.15 no.5
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• pp.1329-1337
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• 2015

By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.

• ETRI Journal
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• v.30 no.3
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• pp.347-354
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• 2008

In this paper, the design of a low-power 512-bit synchronous EEPROM for a passive UHF RFID tag chip is presented. We apply low-power schemes, such as dual power supply voltage (VDD=1.5 V and VDDP=2.5 V), clocked inverter sensing, voltage-up converter, I/O interface, and Dickson charge pump using Schottky diode. An EEPROM is fabricated with the 0.25 ${\mu}m$ EEPROM process. Power dissipation is 32.78 ${\mu}W$ in the read cycle and 78.05 ${\mu}W$ in the write cycle. The layout size is 449.3 ${\mu}m$ ${\times}$ 480.67 ${\mu}m$.

• Journal of computational fluids engineering
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• v.20 no.3
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• pp.20-26
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• 2015

This paper introduces a computational method for analysis of the 6-DOF motions of a ship in waves using an overset grid technique which consists of inner and outer domains for representing body motions and numerical wave tank, respectively. High order interpolation scheme is employed to increase numerical accuracy over the interface where physical values, such as velocities and pressure, interact between the inner and outer domains. The numerical schemes and algorithm are addressed in the present paper. An application to motion of KCS container carrier in head waves is presented, and the comparison of responses on heave and pitch motions shows good agreement with those of model tests.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1017-1038
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• 2015

This paper presents a strengthening method that involves the use of ferrocement jackets and chamfers to relocate plastic hinge for non-seismically designed reinforced concrete exterior beam-column joints. An experimental study was conducted to assess the effectiveness of the proposed strengthening method. Four half-scale beam-column joints, including one control specimen and three strengthened specimens, were prepared and tested under quasi-static cyclic loading. Strengthening schemes include ferrocement jackets with or without skeleton reinforcements and one or two chamfers. Experimental results have indicated that the proposed strengthening method is effective to move plastic hinge from the joint to the beam and enhance seismic performance of beam-column joints. Shear stress and distortion within the joint region are also reduced significantly in strengthened specimens. Skeleton reinforcements in ferrocement provide limited improvement, except on crack control. Specimen strengthened by ferrocement jackets with one chamfer exhibits slight decrease in peak strength and energy dissipation but with increase in ductility as compared with that of two chamfers. Finally, a method for estimating moment capacity at beam-column interface for strengthened specimen is developed. The proposed method gives reasonable prediction and can ensure formation of plastic hinge at predetermined location in the beam.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5A
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• pp.495-501
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• 2011

IEFT proposed MIPv6 for supporting IP movement. Mobile Node is involved signaling that cause handover latency in MIPv6. Recently, Proxy Mobile IPv6 is proposed by IETF for network-based mobility management to reduce overhead in mobile node still suffers from packet loss. PMIPv6 can decrease handover latency which related overhead in MN by using network agent. Therefore, MIPSHOP Working Group proposed fast handover for PMIPv6, fu this paper, we proposed packet bicasting scheme on dual interface mobile node that can support fast handover using PMIPv6 schemes. Further, a numerical analysis is provided to show the benefits of our scheme. In the analysis, various parameters are used to compare our scheme with another procedure.

• Nuclear Engineering and Technology
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• v.42 no.2
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• pp.211-218
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• 2010

An analysis model on debris transport in the containment floor of pressurized water reactors is developed in which the flow field is calculated by Eulerian conservation equations of mass and momentum and the debris particles are traced by Lagrange equations of motion using the pre-determined flow field data. For the flow field calculation, two-dimensional Shallow Water Equations derived from Navier Stokes equations are solved using the Finite Volume Method, and the Harten-Lax-van Leer scheme is used for accuracy to capture the dry-to-wet interface. For the debris tracing, a simplified two-dimensional Lagrangian particle tracking model including drag force is developed. Advanced schemes to find the positions of particles over the containment floor and to determine the position of particles reflected from the solid wall are implemented. The present model is applied to calculate the transport fraction to the Hold-up Volume Tank in Advanced Power Reactors 1400. By the present model, the debris transport fraction is predicted, and the effect of particle density and particle size on transport is investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1701-1703
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• 2006

Here we describe a novel driving scheme in the form of negative AC bias stress (NAC) to compensate shift in the threshold voltage for hydrogenated amorphous silicon (${\alpha}$-Si:H) thin film transistor (TFT) for AMOLED applications. This scheme preserves the threshold voltage shift of ${\alpha}$-Si:H TFT for infinitely long duration of time(>30,000 hours) and thereby overall performance, without using any additional TFTs for compensation. We briefly describe about the possible driving schemes in order to implement for real time AMOLED applications. We attribute most of the results based on concept of plugging holes and electrons across the interface of the gate insulator in a controlled manner.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.280-286
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• 2006

The paper proposes a new protection algorithm for reliable operation of grid-interfaced PV system, which can flexibly interact with conventional protective schemes of power utility grid not only to prevent damages to utility or public persons and utility apparatus caused by malfunction or failure in distribution network protection system, but also to protect a PV system itself from faults or abnormal conditions of the network. The proposed algorithm is based on reclosing characteristics of the distribution system. As a network fault occurs, the new scheme determines whether it is momentary or permanent and responds in a pre-programmed way to the fault. For permanent outage, the proposed algorithm shuts down inverter's operations but monitoring system voltage and frequency at the point of common coupling with grid. When it comes to the momentary outage, Inverter starts stand-by operation mode so that it can be automatically connected to the grid without start-up procedures as soon as the system voltage and frequency returns into the normal operation range. In order to investigate' and evaluate the PV system operation, simulation study based on PSCAD/EMTDC has been carried out to verify the performance of the proposed protection scheme.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.1
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• pp.47-52
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• 2016

Fault location identification in the transmission line is an essential part of quick service restoration for maintaining a stable in power system. The application of digital schemes to protection IEDs has led to the development of digital fault locators. Normally, the impedance measurement had been used to for the location detection of transmission line faults. It is well known that the most accurate fault location scheme uses two-ended measurements. This paper deals with the complete design of a fault locator using GPS time-synchronized phasor for transmission line fault detection. The fault location algorithm uses the transmitted relaying signals from the two-ended terminal. The fault locator hardware consists of a Main Processor Unit, Analog Digital Processor Unit, Signal Interface Unit, and Power module. In this paper, sample real-time test cases using COMTRADE format of Omicron apparatus are included. We can see that the implemented fault locator identified all the test faults.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4618-4639
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• 2018

One of the most innovative paradigms for the next-generation of wireless cellular networks is the cloud-radio access networks (C-RANs). In C-RANs, base station functions are distributed between the remote radio heads (RHHs) and base band unit (BBU) pool, and a communication link is defined between them which is referred as the fronthaul. This leveraging link is expected to reduce the CAPEX (capital expenditure) and OPEX (operating expense) of envisioned cellular architectures as well as improves the spectral and energy efficiencies, provides the high scalability, and efficient mobility management capabilities. The fronthaul link carries the baseband signals between the RRHs and BBU pool using the digital radio over fiber (RoF) based common public radio interface (CPRI). CPRI based optical links imposed stringent synchronization, latency and throughput requirements on the fronthaul. As a result, fronthaul becomes a hinder in commercial deployments of C-RANs and is seen as one of a major bottleneck for backbone networks. The optimization of fronthaul is still a challenging issue and requires further exploration at industrial and academic levels. This paper comprehensively summarized the current challenges and requirements of fronthaul networks, and discusses the recently proposed system architectures, virtualization techniques, key transport technologies and compression schemes to carry the time-sensitive traffic in fronthaul networks.