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沈寬植 江原大學校 産業科學硏究所 1982 産業技術硏究 Vol.2 No.-
The fracture of a hot rolled SM 45C steel plate was investigated for various crack ratio, thickness and loading point using the method of J-integral. It was found that the stable crack growth increased as the thickness and crack ratio of the specimen. the results are summerized as follows. 1.The more crack ratio increase, the less fracture toughness tend to. 2.Considering fracture toughness, a thin specimen is stronger a thick one. 3.Considering only the bending of specimen without thickings of the axial direction, we can get J₁сvalue decreased about 10 percentage within the scope of experimental crack ratio.
심관식,김용구,문채주 한국조명전기설비학회 2003 조명·전기설비학회논문지 Vol.17 No.3
논문에서는 대규모 계통의 미소신호안전도 평가 및 해석을 위해 고유치 감도/perturbation 이론에 근거한 상정사고 지표를 제안하였으며 이를 실제 계통에 적용한 결과를 기술하였다. 선로정수와 제어기점수에 대한 미소신호 안정도 상정사고 지표를 제시하였고 이로부터 심각한 저주파진동 문제를 발생할 수 있는 파라메타들을 선택하였다. 또한 각 발전기의 발전량 증감에 대한 고유치 변화로부터 미소신호안정도 상정사고를 일으킬 수 있는 발전기들을 선택하였다. 이 논문에서는 모든 결과들을 2000년 KEPCO 실계통의 시간영역해석과 비교 검증하여 제안한 미소신호안정도 상정사고 해석법이 정확함을 확인하였다. Contingency analysis is one of the most important tasks encountered by planning and operation of lafe scale power systems. This paper describes a new contingency analysis methods for small signal security assessment based on the eigen-sensitivity/perturbation of the electromechanical oscillation modes. The eigen-sensitivity/perturbation with respect to line suceptances and controller parameters can he used to find possible sources of the system instability, and to select contingency for small signal stability. Also, the contingency selection to identify critical generators for MW changes can be obtained by computing the relative movement of the system oscillation modes. The proposed algorithm has been successfully tested on the KEPCO systems which is comprised of 791-bus, 1575-branch and program PSS/E
문채주,장영학,심관식 木浦大學校 工業技術硏究所 1998 工業技術硏究誌 Vol.8 No.-
New eigen-sensitivity theories of the augmented matrix are applied to small signal stability analysis of EPRI one-machine infinite-bus system and New England 10-machine 39-bus test system. First and second order eigenvalue sensitivities are computed for changes of the parameters of line reactance and controllers including exciter, turbine/governor and PSS. It is found in many cases that since eigenvalue trajectories for parameter changes are nonlinear and first order estimate is not adequate for relatively large variation in parameters. Hence second order estimate is essential to guarantee accuracy for wide range of parameter changes.
Synchrophasor를 이용한 한전계통의 저주파 진동 해석 초기 결과
심관식(Kwan-Shik Shim),김상태(Sang-Tae Kim),남해곤(Hae-Kon Nam),최준호(Joon-Ho Choi) 대한전기학회 2014 전기학회논문지 Vol.63 No.1
The parameters of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. This paper describes an initial result for extraction of dynamic parameters from synchrophasor measurements collected on the KEPCO system. Dominant modes of the system are estimated by oscillation detecting program in K-WAMS. The critical wide-area modes of KEPCO system have frequencies in the 0.4 to 0.7Hz range. And the local mode causing the low frequency oscillation of generators located on the west coast area has in the frequency 0.97 and 1.25 Hz, respectively. This results can serve as a reference in the future for reliable system operation in KEPCO system.
심관식(Kwan-Shik Shim),남해곤(Hae-Kon Nam),김용구(Yong-Gu Kim),문영환(Young-Hoan Moon),김상태(Sang-Tae Kim) 대한전기학회 2009 전기학회논문지 Vol.58 No.7
The present study explained the phenomenon that low frequency oscillation is synchronized with discrete data obtained from a wide area system, and a sync search method. When a disturbance occurs in an power system, various controllers operate in order to maintain synchronization. If the system’s damping is poor, low frequency oscillations continue for a long time and the oscillations are synchronized with one another at specific frequency. The present study estimated dominant modes, magnitude and phase of signals by applying parameter estimation methods to discrete signals obtained from an power system, and performed sync search among wide area signals by comparing the estimated data. Sync search was performed by selecting those with the same frequency and damping constant from dominant oscillation modes included in a large number of signals, and comparing their magnitude and phase. In addition, we defined sync indexes in order to indicate the degree of sync between areas in a wide area system. Furthermore, we proposed a wide area sync search method by normalizing mode magnitude in discrete data obtained from critical generator of the wide area. By applying the sync search method and sync indexes proposed in this study to two area systems, we demonstrated that sync scanning can be performed for discrete signals obtained from power systems.
Synchrophasor를 이용한 한전계통의 저주파 진동 스펙트럴 해석
심관식(Kwan-Shik Shim),최준호(Jun-Ho Choi),김상태(Sang-Tae Kim) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.12
The parameters of electromechanical modes offer considerable insight into the dynamic stability properties of a power system. This paper presents a results of a LFO(low-frequency oscillation) based on the time-synchronized signals measured by synchrophasor in the rolling blackout. Spectral analysis was performed, and critical parameters were estimated using the data acquired from synchrophasors installed in the KEPCO system. As significant modes, a 0.68 Hz oscillation mode that occurred prior to the forced load shedding in the rolling blackout was estimated. Such an oscillation mode can cause an uncontrollable blackout. Therefore, the system should be operated so that significant oscillation modes are not activated. This results can serve as a reference in the future for reliable system operation in the event of a similar blackout.