• Wind and Structures
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• v.39 no.1
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• pp.1-14
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• 2024

Widespread damages from extreme winds have attracted lots of attentions of the resilience assessment of power distribution systems. With many related environmental parameters as well as numerous power infrastructure components, such as poles and wires, the increased challenge of power asset management before, during and after extreme events have to be addressed to prevent possible cascading failures in the power distribution system. Many extreme winds from weather events, such as hurricanes, generate widespread damages in multiple areas such as the economy, social security, and infrastructure management. The livelihoods of residents in the impaired areas are devastated largely due to the paucity of vital utilities, such as electricity. To address the challenge of power grid asset management, power system clustering is needed to partition a complex power system into several stable clusters to prevent the cascading failure from happening. Traditionally, system clustering uses the Binary Decision Diagram (BDD) to derive the clustering result, which is time-consuming and inefficient. Meanwhile, the previous studies considering the weather hazards did not include any detailed weather-related meteorologic parameters which is not appropriate as the heterogeneity of the parameters could largely affect the system performance. Therefore, a fragility-based network hierarchical spectral clustering method is proposed. In the present paper, the fragility curve and surfaces for a power distribution subsystem are obtained first. The fragility of the subsystem under typical failure mechanisms is calculated as a function of wind speed and pole characteristic dimension (diameter or span length). Secondly, the proposed fragility-based hierarchical spectral clustering method (F-HSC) integrates the physics-based fragility analysis into Hierarchical Spectral Clustering (HSC) technique from graph theory to achieve the clustering result for the power distribution system under extreme weather events. From the results of vulnerability analysis, it could be seen that the system performance after clustering is better than before clustering. With the F-HSC method, the impact of the extreme weather events could be considered with topology to cluster different power distribution systems to prevent the system from experiencing power blackouts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.5
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• pp.250-257
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• 1985

High order filters are usually realized by cascading second order stages. In this paper, a simple method of pole-zero pairing in the high order band-pass and band-reject filter realization of the elliptic functions is proposed for the enhancement of overall dynamic range. Futrhermore, the optimum sequence of the various biquads of high-pass notch, low-pass notch and symmetrical notch etc., is developed for the elliptic band-pass and band-reject filters.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.146-148
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• 2001

LIGBT의 캐소드에 전류 제한 능력이 있는 LDMOS를 직렬 연결하여 LIGBT의 전류가 기생 사이리스터가 동작하게 되는 지점까지 증가하는 것을 억제함으로써 기생 사이리스터의 동작으로 인한 LIGBT의 불안정 동작 효과적으로 방지하는 새로운 구조의 LIGBT를 제안한다. 또한 턴-오프 시에 LDMOS의 전류 차단 능력에 의해 전류가 기존의 소자에 비해 빠르게 감소하는 효과로 인해 빠른 스위칭 속도를 얻을 수 있었다.

• Journal of electromagnetic engineering and science
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• v.5 no.1
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• pp.43-47
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• 2005

Microwave or optical photonic band-gap(PBG) structures are conventionally realized by cascading distributive elements in a periodic pattern. However, the frequency bandwidth obtained through such plainly periodic arrangement is typically narrow, corporate with a relatively high rejection side-lobe band. To alleviate such problems, a design involving a chirping and tapering technique is hence introduced and employed. The design has been applied in both a planar stratified dielectric medium as well as a strip-line transmission line structure, and results are validated when compared with the corresponding conventional PBG structure.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.29-32
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• 1992

In this paper, a systolic array structure is derived from the realization of 2-D IIR digital filters directed from the SFG(signal flow graph). After realized the 1-D formed partial systolic array, we implemented the complete systolic array to be cascaded 1-D form. The cascading of partial systolic arrays reduce the storage element which sued to delay input signal. 1-D systolic array is derived from that DG is designed through local communication approach and then it mapping to SFG. The derived structure is very simple and has high throughput because during new imput sample is supplied, new output is obtained every sampling period. And broadcast input signal is eliminated. Since the systolic array has property of regularity, modularity, local interconnection and highly synchronized multiprocessing, thus is very suitable for VLSI implementation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.506-514
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• 2010

Defense systems are needed to prevent catastrophic failures of a power grid due to cascaded events. Cascaded events can be occurred by power flow overload. Especially, it is the most dangerous problem that overload line is outage, because it can make the power system face danger of cascaded. In this paper, vulnerability evaluation for monitoring wide are outage is proposed using by configuration information of transmission systems. This method of vulnerability evaluation is considered direct effect and indirect effect of power flow, especially overload. What is more, it can be used when the configuration of power system changes, as simple fault occurs or maintenance of facility. In the case studies, the estimation and simulation network have been testified and analysed in PSSE and C programming.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.278_279
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• 2009

Nowaday, many people study about Black-Out. In this paper, I introduce how to calculate the Dangerous Index against Black-Out, and prediction of Distance relay error action on Zone 3. we consider the real data by I-PIU which will be set on the system. The dangerous Index is calculated three index about Cascading. The prediction of Distance relay is considered by other facilities of power system. This two algorithm can be used on the center system, when the system is on danger, also on the normal states for security.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.463-469
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• 2016

In this paper, the use of a dual composite right/left-handed coplanar waveguide (CPW) transmission line is proposed for the design of a band rejection filter. The notch property of the filter is achieved by combining the convex signal line with the shorted concave meander line, and the equivalent circuit model is extracted from the geometry of the unit cell for organizing the band rejection property. Then the equivalent parameters of the unit cell are analyzed to identify those behaviors. And the dispersion characteristics and energy distributions are simulated. In the end, the band rejection filter is manufactured by cascading two proposed unit cells. We show that the measurement result for the resonant frequency demonstrates good agreement with the simulation result and the band rejection filter provides a rejection performance of 17.5 dB at the stopband frequency ranging from 869 MHz to 894 MHz.

• IE interfaces
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• v.15 no.1
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• pp.55-63
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• 2002

This paper utilizes the FIDO methodology (Function, Information, Dynamic, Organization modeling) which is an enterprise modeling tool that can describe inter-organizational interaction (specifically between prime and sub contractors in this experiment). FIDO follows the standard IDEFO rules in order to demonstrate how a cascading information flow can evolve from a customer to a prime to a subcontractor in a concurrent manner, in a supply chain environment. Background on these processes is presented, followed with the newly derived process and methodology. This is presented in a supply chain management context, and results from an actual experiment at Motorola utilizing subcontractors that supply custom machine parts is presented and reviewed.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1864-1872
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• 2014

Maloperation of protective relays is one of the major causes for cascading tripping in WANS. Another line trip followed by a previous line trip may occur due to overloading of the line, because of the load redistribution or unwanted trip of a backup relay due to change in the flow of fault current. Evaluation of each line is required by considering both of these effects. A new index named Line Security Index (LSI) is proposed in this paper which combines both Vulnerability Index (VI) and Protectability Index (PI) to completely evaluate the security of individual lines and their importance in the power grid. Computer simulations have been performed on the Korean power grid data to establish the feasibility of the proposed idea.