• Journal of Korea Multimedia Society
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• v.18 no.12
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• pp.1468-1474
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• 2015

Efficient spectrum sharing is an important issue in Device-to-Device (D2D) communications underlaying cellular networks as it can mitigate the interference to cellular users and improve the performance of the systems. In this paper, we formulate the radio resource allocation in D2D communications as a mixed nonlinear integer programing. We show the formulated problem is NP-hard and thus a polynomial time algorithm to solve is not possible. Since such a problem is very hard to obtain the optimal solution within a short running time, we instead propose a fast heuristic suboptimal algorithm to mitigate the interference caused to cellular users and improve the performance of the systems. Simulation results are provided to evaluate the performance of the proposed algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1547-1553
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• 2017

Due to the high penetration ratio of dispersed generations, overvoltage problem of the feeder has become more an important issue in distribution system operation. This paper proposes a new method for the smart inverter to control reactive power to mitigate voltage rise by the reverse power flow from the DGs. The proposed method controls reactive power based on current measurement while conventional methods use voltage measurement which include unacceptably large errors. Various case studies using MATLAB simulation have been performed to verify effectiveness of proposed method.

• The Journal of Information Systems
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• v.14 no.3
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• pp.23-30
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• 2005

Computer attacks on vulnerable software are ubiquitous. Today's attacks on client PCs can be used to create armies of zombie computers that are capable of wide reach attacks on high profile businesses and governments. The simple act of patching software vulnerabilities will certainly mitigate this problem, but patching has its own set of problems. Further, it is frequently the case that patches which are available to mitigate vulnerabilities are not being made on a timely basis and sometimes are not being made at all. One solution to the patch management dilemma is outsourcing. This paper notes that outsourcing is not a carte blanche decision that can be made based on dollars, but rather that a contingency decision matrix can provide guidance on outsourcing solutions for patch management and other security components as well. The matrix recognizes that IS staff expertise and employee security awareness are two important factors in the outsourcing decision.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.399-403
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• 2005

In this paper, we analyze on the effect of RC filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of switching surge appears more serious in high voltage induction motor than low voltage induction motor. Consequently, we demonstrated that the RC filter connected to the motor terminals greatly reduces the transient voltage stress md ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• Journal of Drive and Control
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• v.11 no.2
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• pp.1-8
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• 2014

In this study, the authors carried out experiments and numerical simulations in order to clarify the pressure pulsation characteristics in multiple-delivery rotating-cam and stationary-cylinder type radial piston pumps. Also, a tee filter was applied to the pump in order to mitigate the pressure pulsation. Through the experiments and simulations, it was known that pressure pulsation with a magnitude higher than 40% of the mean load pressure could occur in the pump used in the experiments. Moreover, it was confirmed that a tee filter designed in this study could effectively mitigate the pressure pulsation.

• Nuclear Engineering and Technology
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• v.45 no.4
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• pp.459-468
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• 2013

During a station blackout (SBO), the initiating event is a loss of Class IV and Class III power, causing the loss of the pumps, used in systems such as the primary heat transporting system (PHTS), moderator cooling, shield cooling, steam generator feed water, and re-circulating cooling water. The reference case of the SBO case does not credit any of these active heat sinks, but only relies on the passive heat sinks, particularly the initial water inventories of the PHTS, moderator, steam generator secondary side, end shields, and reactor vault. The reference analysis is followed by a series of sensitivity cases assuming certain system availabilities, in order to assess their mitigating effects. This paper also establishes the strategies to mitigate SBO accidents. Current studies and strategies use the computer code of the Integrated Severe Accident Analysis Code (ISAAC) for Wolsong plants. The analysis results demonstrate that appropriate strategies to mitigate SBO accidents are established and, in addition, the symptoms of the SBO processes are understood.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.291-296
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• 2021

Recently, the dual-polarized antenna array has drawn attention due to the dependency of its signal processing gain on the signal polarization. Even though this polarization dependency makes it possible to mitigate a non-right-hand circularly polarized (non-RHCP) jamming signal from the same direction as a GPS signal, the dual-polarized antennas are not yet widely used for various applications. This study suggests a method that can acquire the polarization dependency of the signal-processing gain by intentionally misaligning antenna elements in a single-polarized antenna array. The simulation results show that the proposed method can successfully mitigate a non-RHCP jammer from the same direction as a GPS signal as if a dual-polarized antenna array does and provide comparable signal-to-jammer-plus-noise ratio (SJNR) performance with a completely aligned single-polarized antenna array and a dual-polarized antenna array.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.4
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• pp.208-213
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• 2018

In this paper, we studied the control strategy of applying STATCOM(static synchronous compensator) to mitigate the FIDVR(fault induced delayed voltage recovery) phenomenon. The proportion of motor loads is gradually increasing which might affect power system stability. Excessive reactive power consumption by the stall of the motor loads causes FIDVR phenomenon. In addition, the low inertia of the small HVAC(heating, ventilation and air conditioner) unit will not separate itself in the event of a contingency, causing system instability. For this reason, we have developed a control strategy that utilizes STATCOM efficiently through static and dynamic analysis. Case studies on a Korean power system have validated the performance of the proposed scheme under severe contingency scenarios. The results have verified that the proposed strategy can effectively mitigate FIDVR and improve the stability and reliability of the system.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.84-87
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• 2018

As the propeller end speed increases, the propeller surface is damaged in the process of bubble formation and dropout. It is intended to prevent the corrosion of the propeller by modifying the shape of the end through the winglet structure to mitigate the cavitation phenomenon. In the case of conventional SUS materials, the cost of production is so high that plastic materials are used to prevent corrosion. This paper aims to mitigate the cavitation by deforming the shape of the end through the winglet structure by using the SMC composite material of the propeller using the existing SUS.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.106-111
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• 2021

This study proposes a control method to mitigate the influence of input capacitors in photovoltaic power curtailment. The influence is analyzed by the power flow in the photovoltaic system. In conventional power curtailment, the power injected to the grid may be increased momentarily because the influence of the input capacitor on the power injected to the grid is not considered. The proposed method limits the change rate of photovoltaic array voltage to prevent a momentary increase in the power injected to the grid. The effectiveness of proposed method, which reduces power overshoot, is verified by experimental tests. The proposed method enables the power grid to operate stably in photovoltaic power curtailment.