• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.420-423
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• 2008

This present work is to find optimum design of a NACA65 axial fan blade with weighted average surrogate model. The numerical analysis by Reynolds-average Navier-Stokes equations with shear stress turbulence(SST) is discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The blade aerodynamic shape is modified by six design variables for the optimization. The blade profile as well as stacking line is modified to enhance blade total efficiency. Six design variables, airfoil maximum camber, maximum camber location, leading edge radius, trailing edge radius, lean angle at 50% span and lean angle at 100% span, are selected for blade profile to enhance the total efficiency. The PBA model which is basically weighted average of the basis surrogates is used to find the optimal design in the design space from the constructed response surface model for the objective function. By the optimization, the total efficiency is increased by 1.4%.

• 대기
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• 제21권2호
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• pp.209-220
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• 2011

A new consensus algorithm for the prediction of tropical cyclone track has been developed. Conventional consensus is a simple average of a few fixed models that showed the good performance in track prediction for the past few years. Meanwhile, the consensus in this study is a weighted average of a few models that may change for every individual forecast time. The models are selected as follows. The first step is to find the analogous past tropical cyclone tracks to the current track. The next step is to evaluate the model performances for those past tracks. Finally, we take the weighted average of the selected models. More weight is given to the higher performance model. This new algorithm has been named as DYTRAP (DYnamic data-base Typhoon tRAck Prediction) in the sense that the data base is used to find the analogous past tracks and the effective models for every individual track prediction case. DYTRAP has been applied to all 2009 tropical cyclone track prediction. The results outperforms those of all models as well as all the official forecasts of the typhoon centers. In order to prove the real usefulness of DYTRAP, it is necessary to apply the DYTRAP system to the real time prediction because the forecast in typhoon centers usually uses 6-hour or 12-hour-old model guidances.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권3호
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• pp.210-216
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• 2006

In the rule based modeling, data partitioning plays crucial role be cause partitioned sub data set implies particular information of the given data set or system. In this paper, we present an empirical study result of the data pattern estimation to find underlying data patterns of the given data. Presented method performs crisp type clustering with given n number of data samples by means of the sequential agglomerative hierarchical nested model (SAHN). In each sequence, the average value of the sum of all inter-distance between centroid and data point. In the sequel, compute the derivation of the weighted average distance to observe a pattern distribution. For the final step, after overall clustering process is completed, weighted average distance value is applied to estimate range of the number of clusters in given dataset. The proposed estimation method and its result are considered with the use of FCM demo data set in MATLAB fuzzy logic toolbox and Box and Jenkins's gas furnace data.

• ETRI Journal
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• 제36권5호
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• pp.714-720
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• 2014

In this paper, we propose the use of data-driven probabilistic utterance-level decision logic to improve Weighted Finite State Transducer (WFST)-based endpoint detection. In general, endpoint detection is dealt with using two cascaded decision processes. The first process is frame-level speech/non-speech classification based on statistical hypothesis testing, and the second process is a heuristic-knowledge-based utterance-level speech boundary decision. To handle these two processes within a unified framework, we propose a WFST-based approach. However, a WFST-based approach has the same limitations as conventional approaches in that the utterance-level decision is based on heuristic knowledge and the decision parameters are tuned sequentially. Therefore, to obtain decision knowledge from a speech corpus and optimize the parameters at the same time, we propose the use of data-driven probabilistic utterance-level decision logic. The proposed method reduces the average detection failure rate by about 14% for various noisy-speech corpora collected for an endpoint detection evaluation.

• 한국경영과학회지
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• 제39권1호
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• pp.1-12
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• 2014

This article proposes a variable sampling interval (VSI) $\bar{X}$ control chart using weighted standard deviation (WSD) method for skewed populations. The WSD method decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts control limits and warning limits of a control chart in accordance with the direction and degree of skewness. A control chart constant is derived for estimating the standard deviation of skewed distributions with the mean of sample standard deviations. The proposed chart is compared with the conventional VSI $\bar{X}$ control chart under some skewed distributions. Simulation study shows that the proposed WSD VSI chart can control the in-control average time to signal (ATS) as an adequate level better than the conventional VSI chart, and the proposed chart can detect a decrease in the process mean of a quality characteristic following a positively skewed distribution more quickly than the standard VSI chart.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1377-1389
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• 2016

This paper presents a target model update scheme for the mean-shift tracking with background weighted histogram. In the scheme, the target candidate histogram is corrected by considering the back-projection weight of each pixel in the kernel after the best target candidate in the current frame image is chosen. In each frame, the target model is updated by the weighted average of the current target model and the corrected target candidate. We compared our target model update scheme with the previous ones by applying several test sequences. The experimental results showed that the object tracking accuracy was greatly improved by using the proposed scheme.

• 디지털융복합연구
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• 제3권1호
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• pp.115-148
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• 2005

This study is intended to suggest a more reasonable and practical method of estimating discount & capitalization rate for valuation of closely-held culture content business, that is, to modify the Buildup Summation Model(which is recommended for the closely-held business by the NACVA) by adopting the weighted ratings in the CT Project Investment Evaluation of the Korea Culture Contents Association to risk factors of the Buildup Summation Model. This method is ease to apply for closely-held culture content business and has advantages in applying the weighted rates based on the characteristics of respective culture contents. And it can make up for the Weighted Average Cost of Capital (WACC) which shows generally low discount rates.

• 전자공학회논문지CI
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• 제43권6호
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• pp.83-91
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• 2006

비디오에 삽입된 플래시라이트는 연속된 프레임사이의 차이 값을 높게 형성하여 장면전환 검출을 위한 임계값 결정에 많은 어려움을 주며, 특히 장면전환 지점으로 잘못 검출되는 문제점을 가지고 있다. 따라서 본 논문에서는 이러한 플래시라이트를 연속된 프레임으로부터 효율적으로 제거하여 신뢰할 수 있는 장면전환 지점을 검출하는 강건한 장면전환 검출 알고리즘을 제안한다. 제안된 방법은 먼저, 연속된 프레임사이의 차이 값 추출을 위하여 객체나 카메라의 움직임에 덜 민감하고 프레임의 공간정보를 이용하는 지역 히스토그램 비교에 의한 추출 식을 사용하며, 추출된 차이 값들의 큰 변이 폭에 의한 임계 값 결정의 문제점을 해결하기 위하여 차이 값들의 동적 압축에 의한 정규화 작업을 수행한다. 또한 추출된 차이 값들의 시간적 연속성의 변이에 따라 플래시라이트가 가지는 특징을 이용하여 플래시라이트와 장면전환 검출을 따로 구분하여 추출할 수 있는 새로운 장면전환 검출 알고리즘을 제안한다. 제안된 방법은 플래시라이트가 들어있는 다양한 비디오 타입으로부터 실험되어졌으며, 실험결과 플래시라이트 검출에 높은 신뢰성과 효율성을 보여주었다.

• 대한토목학회논문집
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• 제34권4호
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• pp.1171-1180
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• 2014

유역의 유효우량을 산정할 경우 NRCS-CN 방법을 이용하는 것이 보통이다. NRCN-CN 방법에서 유역의 유출특성을 나타내는 중요한 인자인 유출곡선지수(CN)은 미국 유역을 대상으로 개발되어졌기 때문에, 미국 이외의 국가에서 적용될 경우 지역의 강우-유출 특성을 반영하지 못하는 한계점을 가지고 있다. 이에 많은 연구에서 유역의 CN값을 보정하는 방법을 제시하고 있다. 본 연구에서는 우리나라에 적절한 유효우량 산정방법을 제시하기 위하여 유역의 CN값을 가중평균하는 방법과 유역의 경사도를 고려하여 CN값을 보정하는 방법을 적용하여 유효우량을 산정하고 이를 관측 유효우량과 비교 분석을 수행하였다. 본 연구 결과, 경사도를 고려하여 CN값을 보정할 경우 유효우량이 전반적으로 크게 산정되었으며, 유효우량의 지속시간 또한 길어지는 것으로 나타났다. 유효우량의 산정방법에 따른 통계학적 오차 분석을 수행한 결과, 경사도로 보정한 CN값을 적용한 가중평균 유효우량 산정방법이 관측 직접유출량과 높은 정확성을 가지는 것으로 나타났다. 또한, 관측 자료를 이용하여 추정한 초기손실량과 GIS 자료를 이용하여 추정한 최대잠재보유수량과의 관계를 분석한 결과, NRCS-CN 방법에서 적용되고 있는 선형가정은 실제 강우-유출 관계와 큰 차이를 가지고 있는 것으로 나타났다.

• 대한원격탐사학회지
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• 제28권6호
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• pp.635-651
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• 2012

To produce a level-3 monthly composite image from daily level-2 Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll-a concentration data set in the East Sea, we applied four average methods such as the simple average method, the geometric mean method, the maximum likelihood average method, and the weighted averaging method. Prior to performing each averaging method, we classified all pixels into normal pixels and abnormal speckles with anomalously high chlorophyll-a concentrations to eliminate speckles from the following procedure for composite methods. As a result, all composite maps did not contain the erratic effect of speckles. The geometric mean method tended to underestimate chlorophyll-a concentration values all the time as compared with other methods. The weighted averaging method was quite similar to the simple average method, however, it had a tendency to be overestimated at high-value range of chlorophyll-a concentration. Maximum likelihood method was almost similar to the simple average method by demonstrating small variance and high correlation (r=0.9962) of the differences between the two. However, it still had the disadvantage that it was very sensitive in the presence of speckles within a bin. The geometric mean was most significantly deviated from the remaining methods regardless of the magnitude of chlorophyll-a concentration values. Its bias error tended to be large when the standard deviation within a bin increased with less uniformity. It was more biased when data uniformity became small. All the methods exhibited large errors as chlorophyll-a concentration values dominantly scatter in terms of time and space. This study emphasizes the importance of the speckle removal process and proper selection of average methods to reduce composite errors for diverse scientific applications of satellite-derived chlorophyll-a concentration data.