• 전기학회논문지P
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• 제50권3호
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• pp.101-108
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• 2001

Frequency is an important operating parameter of a power system. Electric power systems sustain transient frequency swings whenever the balance between generation and load does not no longer hold. To cope with this constraints, it requires an accurate and high speedy frequency deviation estimation technique and suitable adjustment to obtain the Power system energy balance. This paper describes a digital signal processing technique for measuring the operating frequency of a power system. The fundamental frequency component of 3-phase signal is first extracted by using an algorithm based on FIR filter. The rate change of the phase angle is used for estimation. To confirm the validity of the proposed algorithm, the simulation studies carried out on a typical 154KV double T/L system by using EMTP software. Some test results are presented in the paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1350-1352
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• 1996

The purpose of image sequence coding is to reduce the spatio-temporal redundancies. For the spatial redundancies, we can use the transform coding such as DCT. In this paper, the optical flow method is applied to solve the problem of temporal redundancies. There are several estimation methods like block matching method and pel-recursive method. Block matching method is easy for a hardware implementation because of the computational simplicity. So, it is now used as the estimation method in MPEG-l, MPEG-2, and H.261. We compared the merits and demerits of the optical flow method and the block matching method in this paper.

• ETRI Journal
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• 제42권6호
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• pp.815-826
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• 2020

We propose a two-dimensional (2D) scattering-center-extraction (SCE) method using sparse recovery based on the compressive-sensing theory, even with data missing from the received radar cross-section (RCS) dataset. First, using the proposed method, we generate a 2D grid via adaptive discretization that has a considerably smaller size than a fully sampled fine grid. Subsequently, the coarse estimation of 2D scattering centers is performed using both the method of iteratively reweighted least square and a general peak-finding algorithm. Finally, the fine estimation of 2D scattering centers is performed using the orthogonal matching pursuit (OMP) procedure from an adaptively sampled Fourier dictionary. The measured RCS data, as well as simulation data using the point-scatterer model, are used to evaluate the 2D SCE accuracy of the proposed method. The results indicate that the proposed method can achieve higher SCE accuracy for an incomplete RCS dataset with missing data than that achieved by the conventional OMP, basis pursuit, smoothed L0, and existing discrete spectral estimation techniques.

• 한국항공운항학회지
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• 제19권4호
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• pp.58-66
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• 2011

The estimation of fatigue integrity is very important for aerospace structures such as engine mount strut. The reason is that the fatigue integrity is essential analysis process to establish the structural stability in aerospace field. Therefore, in this paper, the process of fatigue analysis and test was performed for engine mount strut to prove the structural fatigue integrity. First of all, the fatigue load spectrum is constructed by considering the small aircraft operating condition. Fatigue analysis is done for the cluster near the welding zone which may have F.C.L.(fracture critical location). The fatigue life of engine mount strut was estimated by the Miner's rule which is the damage summation method. Finally, Fatigue test is performed to verify the fatigue integrity. The estimation process of fatigue integrity for engine mount strut of small aircraft may help the design.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.930-933
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• 2006

A new algorithm for satellite microwave rainfall retrievals over the land of Taiwan using TMI (TRMM Microwave Imager) data on board TRMM (Tropical Rainfall Measuring Mission) satellite is described in this study. The scattering index method (Grody, 1991) was accepted to develop a rainfall estimation algorithm and the measurements from Automatic Rainfall and Meteorological Telemetry System (ARMTS) were employed to evaluate the satellite rainfall retrievals. Based on the standard products of 2A25 derived from TRMM/PR data, the rainfall areas over Taiwan were divided into convective rainfall area and stratiform rainfall areas with/without bright band. The results of rainfall estimation from the division of rain type are compared with those without the division of rain type. It is shown that the mean rainfall difference for the convective rain type is reduced from -6.2mm/hr to 1.7mm/hr and for the stratiform rain type with bright band is decreased from 10.7 mm/hr to 2.1mm/hr. But it seems not significant improvement for the stratiform rain type without bright band.

• 대한전자공학회논문지
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• 제26권1호
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• pp.78-87
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• 1989

본 논문에서는 백색 Gauss 잡음이 섞인 연속영상으로 부터 물체의 이동정보를 검출하기 위하여 최소자승추정의 시공간경사법을 제안하였다. 제안된 방법은 하나의 이동물체를 실시간으로 추적하도록 고속의 16-bit 마이크로 프로세서를 사용한 자동목표 추적장치에 적용되었다. 실험결과 제안된 방법은 기존의 최소자승추정의 시공간경사법에 비해서 매우 우수한 성능을 보였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.49-56
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• 1999

In this paper, the general formula of disparity estimation based on Bayesian Maximum A Posteriori (MAP) algorithm is derived. The generalized formula is implemented with the plane configuration model and applied to multiple baselined stereograms. The probabilistic plane configuration model consists of independence and similarity among the neighboring disparities in the configuration. The independence probabilistic model reduces the computation and guarantees the discontinuity at the object boundary region. The similarity model preserves the continuity or the high correlation of disparity distribution. In addition, we propose a hierarchical scheme of disparity compensation in the application to multiple-view stereo images. According to the experiments, the derived formula and the proposed estimation algorithm outperformed other ones. The proposed probabilistic models are reasonable and approximate the pure joint probability distribution very well with decreasing the computations to O(n(D)) from O(n(D)4) of the generalized formula. And, the hierarchical scheme of disparity compensation with multiple-view stereos improves the performance without any additional overhead to the decoder.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권2호
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• pp.438-455
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• 2024

Recently, many unsupervised learning-based models have emerged for Just Noticeable Difference (JND) estimation, demonstrating remarkable improvements in accuracy. However, these models suffer from a significant drawback is that their heavy reliance on handcrafted priors for guidance. This restricts the information for estimating JND simply extracted from regions that are highly related to handcrafted priors, while information from the rest of the regions is disregarded, thus limiting the accuracy of JND estimation. To address such issue, on the one hand, we extract the information for estimating JND in an Adversarial Complementary Learning (ACoL) way and propose an ACoL-JND network to estimate the JND by comprehensively considering the handcrafted priors-related regions and non-related regions. On the other hand, to make the handcrafted priors richer, we take two additional priors that are highly related to JND modeling into account, i.e., Patterned Masking (PM) and Contrast Masking (CM). Experimental results demonstrate that our proposed model outperforms the existing JND models and achieves state-of-the-art performance in both subjective viewing tests and objective metrics assessments.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.1137-1141
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• 2004

본 연구에서는 Probability Weighted Moments의 새로운 선형조합기법인 LQ-moments를 이용하여 GEV 분포의 매개변수를 추정하고 L, LH, LQ-moments를 사용하여 뉴욕주의 Donnattsburg에 위치한 Independence River의 홍수량을 빈도 해석하였다. LH, LQ-moments가 제시된 근본적인 이유는 L-moments가 극치값에 내해 지나치게 민감한 단점을 보완하기 위해서인데, 이번 연구의 결과에 의하면 오히려 LH, LQ-moments가 극치값에 대해 민감하게 반응하여 부정확한 결과가 도출되었다. 그러므로 항상 LH, LQ-moments가 L-moments의 대안이 될 수 있는 것은 아님을 알게 되었다. 그리고 수학적 유도에서 L, LH, LQ-moments는 좀더 쉽고 간편한 메개변수 추정을 위해 Probability Weighted Moments의 선형조합을 통해 고안되었다는 공통점을 가지고 있지만, 이 점을 제외한 나머지 부분의 수식 유도에서는 서로 많은 차이가 있어서 지역적인 특성과 확률분포형의 특성을 고려하여 L, LH, LQ-moments 중에서 선별 사용해야 할 것이다.

• 한국대기환경학회지
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• 제6권2호
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• pp.168-175
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• 1990

Pasquill stability class (PSC) was evaluated with Monin-Obukhov length (L) using the data observed at a height of 213m meteorological tower in Tsukuba, Japan. PSC was determined with wind speed and insolation (net radiation at night), and L was calculated with the heat flux and the friction velocity obtained at 25m by the eddy correlation method. To evaluate PSC with L, for every class of Pasquill stability (from A to F class), percentiles and median of L were used. Results show that for every class of Pasquill stability, L varies so widely that PSC does not adequately represent the atmospheric stability conditions. The scheme which estimates L using air temperature at two levels and wind speed at single level was developed. Comparison between estimated L by the scheme and observed L reveals that the scheme is better than PSC. Furthermore, the scheme is more advantageous than PSC because it uses air temperature at two levels instead of insolation which is more difficult to observe in the field than air temperature.