• 한국측량학회지
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• 제18권1호
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• pp.19-23
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• 2000

1990년 이래로, GPS 기술은 지각 움직임 연구에 적용되어 왔으며 본 논문은 반복된 GPS 관측으로부터 (1995-1998) Cam Lo 단층(Quang Tri province, Vietnam)의 지각 운동에 대한 연구 결과를 설명하였다 연구 대상지역은 위도 N 16 40' 10", 경도 E 106 58' 40"의 Vietnam 중앙부에 위치하며 그 규모는 상대적으로 작다. GPS네트워크는 6개의 관측점들로 이루어져 있으며 기선거리는 3-11 km이고, 3개의 tectonic 지역에 위치한다. GPS 데이터 획득은 1995년 5월과 1998년 3월에 두 개의 캠패인으로 모든 관측점들에서 수행되어졌다. 연구결과, 좌표 변화와 표준편차를 고려할 때 대상지역이 움직이고 있었고, 수평 변화보다는 수직 변화가 더 크게 발생하였다. 본 논문의 결과는 지질 전문가에 Cam Lo 단층지역의 지구물리 해석에 흥미로운 자료를 제공할 것이고 베트남의 단층 활동 연구를 고무시킬 것으로 기대된다. 것으로 기대된다.

• 한국정보전자통신기술학회논문지
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• 제8권3호
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• pp.195-202
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• 2015

소프트웨어 고장분석을 위한 비동질적인 포아송과정에서 결함당 고장발생률이 상수이거나, 단조 증가 또는 단조 감소하는 패턴을 가질 수 있다. 본 논문에서는 결함의 기대값을 가정하는 유한고장소프트웨어 NHPP모형과 수리시점에서도 고장이 발생할 상황을 반영하는 무한고장 NHPP모형들을 비교 제시하였다. 소프트웨어 신뢰성분야에서 많이 사용되는 지수파우어분포에 근거한 유한고장과 무한고장 소프트웨어 신뢰성모형에 대한 비교문제를 제시하였다. 그 결과 유한고장모형이 무한고장모형보다 효율적으로 나타났다. 그리고 모수추정법은 최우추정법을 이용하였다. 이 연구를 통하여 소프트웨어 개발자들은 소프트웨어 고장현상을 파악하는데 어느 정도 도움을 줄 수 있을 것으로 사료된다.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.535-544
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• 2017

In-flight aircraft engine performance estimation is one of the key techniques for advanced intelligent engine control and in-flight fault detection, isolation and accommodation. This paper detailed the current performance degradation estimation methods, and an improved hybrid Kalman filter via velocity-based LPV (VLPV) framework for these needs is proposed in this paper. Composed of a nonlinear on-board model (NOBM) and VLPV, the filter shows a hybrid architecture. The outputs of NOBM are used for the baseline of the VLPV Kalman filter, while the system performance degradation factors on-line estimated by the measured real system output deviations are fed back to the NOBM for its updating. In addition, the setting of the process and measurement noise covariance matrices' values are also discussed. By applying it to a commercial turbofan engine, simulation results show the efficiency.

• ETRI Journal
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• 제43권4호
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• pp.728-745
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• 2021

Carbon nanotube field-effect transistors (CNTFETs) have been widely studied as a promising technology to be included in post-complementary metal-oxide-semiconductor integrated circuits. Despite significant advantages in terms of delay and power dissipation, the fabrication process for CNTFETs is plagued by fault occurrences. Therefore, developing a fast and accurate method for estimating the reliability of CNTFET-based digital circuits was the main goal of this study. In the proposed method, effects related to faults that occur in a gate's transistors are first represented as a probability transfer matrix. Next, the target circuit's graph is traversed in topological order and the reliabilities of the circuit's gates are computed. The accuracy of this method (less than 3% reliability estimation error) was verified through various simulations on the ISCAS 85 benchmark circuits. The proposed method outperforms previous methods in terms of both accuracy and computational complexity.

• Structural Engineering and Mechanics
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• 제85권3호
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• pp.381-391
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• 2023

The seismic performance of the tall building equipped with a tuned mass damper (TMD) considering soil-structure interaction (SSI) effects is well studied in the literature. However, these studies are performed on the nominal model of the seismic-excited structural system with SSI. Hence, the outcomes of the studies may not valid for the actual structural system. To address the study gap, the reliability theory as a useful and powerful method is utilized in the paper. The present study aims to carry out reliability analyses on tall buildings equipped with TMD under near-field pulse-like (NFPL) ground motions considering SSI effects using a subset simulation (SS) method. In the presence of uncertainties of the structural model, TMD device, foundation, soil, and near-field pulse-like ground motions, the numerical studies are performed on a benchmark 40-story building and the failure probabilities of the structures with and without TMD are evaluated. Three types of soils (dense, medium, and soft soils), different earthquake magnitudes (M_w = 7,0. 7,25. 7,5 ), different nearest fault distances (r = 5. 10 and 15 km), and three seismic performance levels of immediate occupancy (IO), life safety (LS), and collapse prevention (CP) are considered in this study. The results show that tall buildings built near faults and on soft soils are more affected by uncertainties of the structural and ground motion models. Hence, ignoring these uncertainties may result in an inaccurate estimation of the maximum seismic responses. Also, it is found the TMD is not able to reduce the failure probabilities of the structure in the IO seismic performance level, especially for high earthquake magnitudes and structures built near the fault. However, TMD is significantly effective in the reduction of failure probability for the LS and CP performance levels. For weak earthquakes and long fault distances, the failure probabilities of both structures with and without TMD are near zero, and the efficiency of the TMD in the reduction of failure probabilities is reduced by increasing earthquake magnitudes and the reduction of fault distance. As soil softness increases, the failure probability of structures both with and without TMD often increases, especially for severe near-fault earthquake motion.

• 전기학회논문지P
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• 제59권2호
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• pp.173-178
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• 2010

Frequency is an important operating parameter of a power system. Due to the sudden change in generation and loads or faults in power system, the frequency is supposed to deviate from its nominal value. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And monitoring and an accurate estimation of the power frequency by timing synchronized signal provided by FDR is essential to optimum operation and prevention for wide area blackout. As most conventional frequency estimation schemes are based on DFT filter, it has been pointed out that the gain error by change in magnitude could cause the defects when the power frequency is deviated from nominal value. In this paper, an advanced frequency estimation scheme using gain compensation for fault disturbance recorders (FDR) is presented. The proposed scheme can reduce the gain error caused when the power frequency is deviated from nominal value. Various simulation using both the data from EMTP package and user's defined arbitrary signals are performed to demonstrate the effectiveness of the proposed scheme. The simulation results show that the proposed scheme can provide better accuracy and higher robustness to harmonics and noise under both steady state tests and dynamic conditions.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.103-109
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• 2003

전력계통의 자동화에 있어 측정되는 데이터의 정확성은 기본적으로 확립되어야 할 요건이다. 측정된 데이터는 통신 장애나 기기 자체의 오동작으로 인해 오차를 포함할 수 있으며, 이러한 오차는 상태추정에 의해 줄어들 수 있으나, 잘못 측정된 일부 값에 의해 상태추정의 전반적인 신뢰도가 저하될 수 있다. 본 논문에서는 가중최소 상태추정과 카이스퀘어 이론에 근거한 잘못 측정된 데이터의 검출 알고리즘이 제안되었으며, 이를 국내 154kV 변전소에 적용하였다. C 언어와 비쥬얼 베이직을 사용하여 GUI 환경의 시뮬레이터를 개발하였으며, 다른 운용 시스템과의 연계를 고려하여 TCP/IP 프로토콜을 탑재하였다.

• 전기학회논문지
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• 제66권6호
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• pp.898-904
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• 2017

DFT(Discrete Fourier Transform) is one of the most widely used method to estimate the phasor of a relaying signal. The harmonics are eliminated by the DFT. However, high frequency components, except for harmonics, are not removed and cause an error in DFT-based phasor estimation process. This paper suggests high frequency noise reduction method by using a newly designed low-pass filter to estimate a signal phasor. When selecting a stop-band cut-off frequency of the low-pass filter, high frequency components generated by faults are considered. To reduce the phasor estimation delay caused by a low-pass filter, this paper proposes a low-pass filter whose settling time is reduced. An adverse effect of high frequency noise on DFT-based phasor estimation is reduced. To evaluate the performance of the proposed method, signals which are collected under a fault condition at a 345[kV] transmission system modeled by EMTP-RV are used.

• 한국지진공학회논문집
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• 제18권3호
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• pp.151-160
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• 2014

Probabilistic tsunami hazard analysis (PTHA) is based on the approach of probabilistic seismic hazard analysis (PSHA) which is performed using various seismotectonic models and ground-motion prediction equations. The major difference between PTHA and PSHA is that PTHA requires the wave parameters of tsunami. The wave parameters can be estimated from tsunami propagation analysis. Therefore, a tsunami simulation analysis was conducted for the purpose of evaluating the wave parameters required for the PTHA of Uljin nuclear power plant (NPP) site. The tsunamigenic fault sources in the western part of Japan were chosen for the analysis. The wave heights for 80 rupture scenarios were numerically simulated. The synthetic tsunami waveforms were obtained around the Uljin NPP site. The results show that the wave heights are closely related with the location of the fault sources and the associated potential earthquake magnitudes. These wave parameters can be used as input data for the future PTHA study of the Uljin NPP site.

• 자원환경지질
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• 제33권1호
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• pp.61-75
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• 2000

Through modeling fault network using thin plate finite element technique in the San Andreas Fault system with slip rate over 1mm/year, as well as elevation, heat flow, earthquakes, geodetic data and crustal thickness, we compare the results with velocity boundary conditions of plate based on the NUVEL-1 plate model and the approximation of deformation in the Great Basin region. The frictional and dislocation creep constants of the crust are calculated to reproduce the observed variations in the maximum depth of seismicity which corresponds to the temperature ranging from $350^{\circ}C$ to $410^{\circ}C$. The rheologic constants are defined by the coefficient of friction on faults, and the apparent activation energy for creep in the lower crust. Two parameters above represent systematic variations in three experiments. The pattern of model indicates that the friction coefficient of major faults is 0.17~0.25. we test whether the weakness of faults is uniform or proportional to net slip. The geologic data show a good agreement when fault weakness is a trend of an additional 30% slip dependent weakening of the San Andreas. The results of study suggest that all weakening is slip dependent. The best models can be explained by the available data with RMS mismatch of as little as 3mm/year, so their predictions can be closely related with seismic hazard estimation, at least along faults where no data are available.