• Journal of Aerospace System Engineering
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• v.9 no.2
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• pp.41-46
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• 2015

The various risk factors that affected schedule, costs and mission success, etc. in development of the satellite. This paper derives the considerable "Cost of Quality" factors in the satellite development phase through the survey of practical techniques in respect of measurement of quality cost in the commercial products manufacturing, and proposes mitigation strategy of quality cost using the approach that can be minimized it.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.300-305
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• 2007

This paper reports an investigation of overvoltages caused by ferroresonance in the distribution system, which consists of a bank of open-delta single-phase voltage transformers. The high voltage sides of the voltage transformer are connected to the distribution system via three single-phase fuse cutouts. Due to the saturation characteristic of the transformer cores, ferroresonance can occur in the condition that the transformer is energized or deenergized with single-phase switching operation of the fuse cutouts. The simulation tool based on EMTP is used to investigate the overvoltages at the high side of voltage transformer. Bifurcation diagrams are used to present the ferroresonance behavior in ranges of different operating conditions. The simulation results are in good agreement with the results from the experiment of 22 kV voltage transformers. The mitigation technique with additional damping resistors in the secondary windings of the voltage transformers will be introduced. Brief discussion will be made on the physical phenomena related to the overvoltage and the damage of voltage transformer.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.5
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• pp.234-241
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• 2005

The performance of passive conductor loop (hereinafter 'loop') method which is used to mitigate the magnetic field around overhead power transmission line is dependent on its configuration and installed location, which are affected by installation conditions of the loops such as objective areas and levels of magnetic field mitigation. Thus, because the design problem of loops is difficult and cumbersome by variety of their configuration and complexity of magnetic coupling mechanism, it is need to be formulated as a computer-based optimum problem to determine the most effective and reasonable loop model satisfying the installation conditions. In this paper, the optimum locations of the multi-wired multiple loops including series reactance compensations are searched by using the genetic algorithm (GA) to mitigate effectively the magnetic fields of relatively near points or far points from transmission line at Am height, and the magnetic fields mitigation characteristics of each loop are analyzed in the view of magnitude, direction and phase of cancellation fields by polarized vector concept to identify their adequacy and rationality for the installation objectives.

• The KIPS Transactions:PartC
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• v.10C no.2
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• pp.125-132
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• 2003

In the paper, we can select the best safeguard as proposed the definite and systematical method and procedure on risk mitigation of risk management for information system. The practical risk mitigation methodology has a good fulfillment procedure and a definition to fulfill procedure on each phase. So, it is easy to fulfill and can apply to any risk management methodology. The practical risk mitigation is composed of 6 phases, which are the existing safeguard assessment, safeguard means selection, safeguard technique selection, risk admission assessment, cost-effective analysis and safeguard embodiment. The practical risk mitigation's advantages are as follow. Efficient selection of safeguards to apply to risk's features with safeguard's means and techniques before embodying safeguards. Prevention of redundant works and security budgets waste as re-using the existing excellent safeguards through the existing safeguard assessment. Reflection of organization's CEO opinions to require special safeguards for the most important information system.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.502-513
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• 2019

Purpose: This study intends to review the procedures for the establishment of the plan for disaster mitigation activities and the system for the management of disaster mitigation activities for the requirements of the enterprise disaster management standard. Method: The requirements, including the activities of each stage of disaster management defined within the scope of the corporate disaster management standard, were identified, the operational cases of 'A' institution were reviewed, and the targets of continuous planning were reviewed to meet the requirements. Result: It was reviewed that the contents and procedures of each phase of disaster management, which is a requirement of the enterprise disaster management standard, are clearly defined, and a task continuity plan is established for each stage of activity. Conclusion: Conclusion : The PDCA model including the activities of each stage of disaster management activities was presented for the requirements of the enterprise disaster management standard, and the disaster mitigation activity management system model of the broad concept of disaster management including prevention and preparedness plans for disasters was presented.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.6
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• pp.21-32
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• 2023

The Environmental Impact Assessment (EIA) plays a pivotal role in predicting the potential environmental impacts of proposed developments and planning appropriate mitigation measures to minimize effects on species. However, as concerns over biodiversity loss rise, there's ongoing debate about the efficacy of these mitigation plans. In this study, we utilized data from EIAs and post-environmental impact surveys to understand the trends in biodiversity during construction and operation phases. By examining 30 urban development projects, we categorized species richness indices of mammals, birds, amphibians, and reptiles into pre-construction, during construction, and post-construction operational stages. The biodiversity trends were analyzed based on the rate of change in these indices. The results revealed three distinct biodiversity change patterns: (A) An initial increase in biodiversity indices post-development, followed by a gradual decline over time; (B) a sustained increase in biodiversity as a result of mitigation measures; and (C) a continuous decline in biodiversity post-development. Furthermore, all species exhibited a higher rate of biodiversity decline during the construction phase compared to the operational phase, with mammals showing the most significant rate of change. Notably, the biodiversity change rate during operation was generally lower than during construction. In particular, mammals seemed to be most influenced by mitigation measures, displaying the smallest rate of change. This study provides empirical evidence on the efficacy of mitigation measures and deliberates on ways to enhance their effectiveness in minimizing the adverse impacts of urban development on biodiversity. These findings can serve as foundational data for addressing terrestrial biodiversity reduction.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.347-354
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• 2002

In this paper, a comparative study on the performance of two-phase and three-phase randomized pulse position PWM scheme for mitigation of audible switching acoustic noise in motor drives Is done. In the randomized pulse position PWM, each of two-phase or three-phase PWM pulses is located randomly in each switching interval. Simulation and experimental efforts were executed to investigate the spread effects of power spectra of inverter output voltage, waveforms of ripple current and audible switching acoustic noise.

• Journal of Power Electronics
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• v.12 no.5
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• pp.821-829
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• 2012

This research article presents a novel approach based on an instantaneous active and reactive power component (p-q) theory for generating reference currents for shunt active filter (SHAF). Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. The performance of the SHAF using the p-q control strategy has been evaluated under various source conditions. The performance of the proposed control strategy has been evaluated in terms of harmonic mitigation and DC link voltage regulation. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed Fuzzy logic controller with different (Trapezoidal, Triangular and Gaussian) fuzzy M.F.s. The proposed SHAF with different fuzzy M.F.s is able to eliminate the uncertainty in the system and SHAF gains outstanding compensation abilities. The detailed simulation results using MATLAB/SIMULINK software are presented to support the feasibility of proposed control strategy. To validate the proposed approach, the system is also implemented on a real time digital simulator and adequate results are reported for its verifications.

• Smart Structures and Systems
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• v.23 no.6
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• pp.669-682
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• 2019

Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.