• Journal of Communications and Networks
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• v.16 no.5
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• pp.534-547
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• 2014

Large-scale failures resulting from natural disasters or intentional attacks are now causing serious concerns for communication network infrastructure, as the impact of large-scale network connection disruptions may cause significant costs for service providers and subscribers. In this paper, we propose a new framework for the analysis and prevention of network service disruptions in large-scale failure scenarios. We build dynamic deterministic and probabilistic models to capture the impact of regional failures as they evolve with time. A probabilistic failure model is proposed based on wave energy behaviour. Then, we develop a novel approach for preventive protection of the network in such probabilistic large-scale failure scenarios. We show that our method significantly improves uninterrupted delivery of data in the network and reduces service disruption times in large-scale regional failure scenarios.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.374-381
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• 2005

The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.285-285
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• 2000

A continuous and reliable electrical energy supply is the objective of any power system operation. A transmission line is the part of the power system where faults are most likely to happen. This paper describes the use of wavelet transform for analyzing power system fault transients in order to determine the fault location. Synchronized sampling was made possible by precise time receivers based on GPS time reference, and the sampled data were analyzed using wavelet transform. This paper describes a fault location monitoring system and fault locating algorithm with GPS, DSP processor, and data acquisition board, and presents some experimental results and error analysis.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.255-259
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• 1997

The essence of meridian collateral and acupoints is an overall physiologic unction with the level of multiple unctional states. However it is a pity that until present, so in this paper described about some experimental results of physical reactions of meridian and acupoints. In order to verify meridian pathway and channel theory of energy in body. It is suppose that substance of meridian is pathway channel of the meridian materials. In basic examination, It was analyzed spectrum of reflection waves after beat or continuos vibrate to meridian point and non-meridian point meridian line and non-meridian line. The characteristics of reflection waves similar to flow channel in hydrodynamic. So it be able to suggest that the meridian is pathway and channel in body.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.04a
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• pp.48-51
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• 2009

Excessive wavy surfaces formed by a cold or hot-rolling process in a thin plate degrade the value of the plate significantly, which is called flatness problem in the industry. It is a result of post-buckling due to the residual stress caused by the rolling process. A unique difficulty of the problem as a buckling problem is that the buckling length is not given but has to be found. a new approach is developed to solve the flatness problem by extending a classic post-buckling analysis method based on the energy principle. The approach determines the buckling length and amplitude. The new solution approach can be used to determine the condition for the maximum rolling production that does not cause the flatness problem.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.165.2-165.2
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• 2011

Flow with suction to water turbine must be in stable state at small hydraulic power plant. But because of water level fluctuation and water gate effect according to irregular supply of cooling water, it would happen to produce bubble and vortex and finally lead to problems in power-plant system. With utilizing the concept design of double size gate, surface water overflowed the overhead of gate for stable flow at suction. We developed the overflow condition and analyzed the design factor with existed one such as water level(overflow amount) and overhead of water gate(overflow figure). Flow test and CFD simulation say that flow have stable state around suction and 20% of wave reduction effect at surface layer after surface water overflow.

• Journal of Powder Materials
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• v.19 no.4
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• pp.297-303
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• 2012

In this study, voltammetry system for realizing high sensitivity nano-labeled sensor of detecting heavy metals was designed, and optimal system operating conditions were determined. High precision digital to analog converter (DAC) circuit was designed to control applied unit voltage at working electrode and analog to digital converter (ADC) circuit was designed to measure the current range of $0.1{\sim}1000{\mu}A$ at counter electrode. Main control unit (MCU) circuit for controlling voltammetry system with 150 MHz clock speed, main memory circuit for the mathematical operation processing of the measured current value and independent power circuit for analog/digital circuit parts to reduce various noise were designed. From result of voltammetry system operation, oxidation current peaks which are proportional to the concentrations of Zn, Cd and Pb ions were found at each oxidation potential with high precision.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2361-2363
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• 1999

The conventional SiC-type of lightning arresters in distribution systems has been replaced by ZnO-type because the ZnO-type has characteristics such as outstanding non linearity, high energy absorption capability, surge suppressing performance, and excellent response to abrupt wave. Out of the various types of lightning arrester failures, some which have been often reported could be prevented in advance. Therefore, the preventive countermeasures which can cope with the failures are strongly required. This paper summed up and analyzed the lightning arrester failures which occurred, from 1983 to 1992, in distribution systems in order to provide fundamental data, classified by year, to make countermeasures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.388-397
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• 2001

This paper addresses characteristics of compressible flow dynamics inside a pipe with an accumulator and an inlet orifice. It also presents a simple but stable numerical method associated with the accumulator-orifice calculation. In particular, a focus is given to developing a method of finding an optimum design of the accumulator-orifice system (i.e., the accumulator size and the throttle resistance) that gives the most effective dissipation of the water-hammering problem. It is found that there exists indeed an optimum set of parameter values for the most effective dissipation of the wave energy.

• Journal of the Korean Chemical Society
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• v.60 no.3
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• pp.163-168
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• 2016

We summarize the discrete variable representation method which is a simple numerical method enabling us to calculate the vibrational energies and wave functions of anharmonic oscillators. The ranges of its parameters well-performing for the calculation of fundamental and overtone transition energies are predicted by analyzing the model of Morse oscillator.