• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2440-2443
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• 2008

This paper presents a three dimensional shape optimization procedure for a low-speed axial flow fan blade with a weighted average surrogate model. Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations. Six variables from airfoil profile and lean are selected as design variables. 3D RANS solver is used to evaluate the objective functions of total pressure efficiency. Surrogate approximation models for optimization have been employed to find the optimal design of fan blade. A search algorithm is used to find the optimal design in the design space from the constructed surrogate models for the objective function. The total pressure efficiency is increased by 0.31% with the weighted average surrogate model.

• 설비공학논문집
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• 제11권6호
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• pp.709-715
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• 1999

To optimize a heating and cooling system, we need an exact solution lot radiant heat transfer in any form of room or building. This paper describes the solution method of view factor by the area weighted average and graphical method to calculate the radiant heat exchange or daylighting level in any form of room or building. This study shows that the area weighted average and graphical methods have many points of merits(calculation speed, correctness and calculation capability in an arbitrary form of room shapes etc.) compared with existing methods

• 디지털산업정보학회논문지
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• 제17권2호
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• pp.1-11
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• 2021

Salt and pepper is a type of impulse noise. It may appear due to an error in the image transmission process and image storage memory. This noise changes the pixel value at any position in the image to 0 (in case of pepper noise) or 255 (in case of salt noise). In this paper, we present an algorithm for SAP noise reduction. The proposed method consists of three steps. In the first step, the location of the SAP noise is detected, and in the second step, the pixel value of the detected location is restored using a weighted average of the surrounding pixel values. In the last step, a reliability matrix around the reconstructed pixels is constructed, and additional correction is performed with a weighted average using this. As a result of the experiment, the proposed method appears to have similar or higher objective and subjective image quality than previous methods for almost all SAP noise ratios.

• 전자공학회논문지CI
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• 제42권4호
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• pp.51-58
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• 2005

본 논문에서는 비디오 시퀀스의 자동분류를 지원하기 위한 기반기술로서, 변형된 $\chi^2$-테스트와 자동 임계치-결정 알고리즘을 이용한 장면전환 검출 기법을 제안하였다. 변형된 $\chi^2$-테스트는 기존의 컬러 히스토그램에서 컬러의 각 채널공간(RGB)에 NTSC표준에 따른 명암도 등급을 따로 계산하여 채널의 차이 값을 보다 세분화 할 수 있으며, 인접한 두 프레임사이의 상대적인 컬러 값의 차이를 강조하는$\chi^2$- 테스트를 결합하여 보다 강건한 장면전환 곁출을 시도하고 있다. 자동 임계치-결정 알고리즘은 변형된 $\chi^2$-테스트를 통하여 획득된 인접한 프레임들 사이의 차이 값들을 이용한다. 먼저, 차이 값들에 대한 전체 평균값을 계산한 후, 이 평균값을 만족하는 차이 값들만을 이용하여 다시 평균값을 계산하며, 이러한 평균값의 연속적인 계산 및 누적을 통하여 분산된 차이 값들로부터 가장 최적의 중간 평균값을 취하여 임계치로 설정하는 방법이다. 실험결과 제안된 장면전환 검출 방법과 자동 임계치-결정 알고리즘은 기존의 접근방법보다 효과적이며, 그 우수성을 보여주었다.

• 한국환경보건학회지
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• 제33권5호
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• pp.359-364
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• 2007

The aim of this study were to assess the personal exposure to volatile organic compounds (VOCs) and to estimate the personal exposure using time-weighted average model. Three target VOCs (benzene, toluene, xylene) were analyzed in personal exposure samples and residential indoor, residential outdoor and workplace indoor microenvironments samples in the iron mill 30 workers during working 5 days. Personal exposure to VOCs significantly correlated with workplace concentration p<0.05), suggesting workplace had strong source and major contribution to personal exposure. Personal exposure could be estimated with time activity pattern and time weighted average (TWA) model of residential indoor and workplace concentrations measured. Time weighted mean microenvironments concentrations were close approximately of personal exposure concentrations. Total exposure for participants can be estimated by TWA with microenvironments measurements and time activity pattern.

• 응용통계연구
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• 제29권7호
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• pp.1283-1294
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• 2016

한국 프로야구팀들의 실점을 설명하기 위한 수비지표를 연구하였다. 출루율과 장타율을 결합한 OPS가 팀들의 득점력을 매우 잘 설명한다는 사실을 동기로 하여 본 논문에서는 팀들의 실점을 설명하기 위한 수비지표를 연구하였다. 여러 가지의 수비지표 중 팀의 실점과 상관관계가 높은 것들을 결합하여 만든 몇 가지의 결합 지표들을 고려하였다. 프로야구 원년인 1982년부터 2015년까지의 정규리그 전 경기 자료를 분석한 결과 수정WHIP와 이닝당피홈런의 가중평균으로 정의되는 가중수정WPH2가 실점을 가장 잘 설명해줬다. 구체적으로 수정WHIP에 34%, 이닝당피홈런에 66%의 가중값을 두는 가중수정WPH2가 팀의 경기당 평균실점과 0.95362의 상관계수를 갖는 최적의 지표인 것으로 나타났다. 이 결과는 Kim과 Kim (2015a)에서 얻어진 지표에 의한 결과보다 좀 더 향상된 결과이다. 시대별 분석에서도 크게 다르지 않은 결과를 얻었다. 또한 얻어진 지표의 값이 좋은 투수 10명씩의 명단을 최근 3년간에 대해 연도별로 작성해보았다.

• Journal of Communications and Networks
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• 제12권5호
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• pp.449-458
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• 2010

In this paper, we present a distributed resource allocation algorithm for multi-cell uplink systems that increases the weighted sum of the average data rates over the entire network under the average transmit power constraint of each mobile station. For the distributed operation, we arrange each base station (BS) to allocate the resource such that its own utility gets maximized in a noncooperative way. We define the utility such that it incorporates both the weighted sum of the average rates in each cell and the induced interference to other cells, which helps to instigate implicit cooperation among the cells. Since the data rates of different cells are coupled through inter-cell interferences, the resource allocation taken by each BS evolves over iterations. We establish that the resource allocation converges to a unique fixed point under reasonable assumptions. We demonstrate through computer simulations that the proposed algorithm can improve the weighted sum of the average rates substantially without requiring any coordination among the base stations.

• 한국대기환경학회지
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• 제17권3호
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• pp.251-258
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• 2001

Indoor and outdoor nitrogen dioxide(NO$_2$) concentrations of 122 houses were measured and compared with measurements of personal NO$_2$ exposure simultaneously . Time activity patterns were used to determine the impacts on NO$_2$ exposure assessment and time weighed average model to estimate the personal NO$_2$ exposure. Most people spent their times more than 80% of indoor and more than 50% in home, respectively. Personal NO$_2$ esposure was found to be significantly associated with both indoor NO$_2$ concentration(r=0.70) and outdoor NO$_2$ concentration (r=0.68). Using time weighted average model, personal NO$_2$ exposure was estimated with NO$_2$ measurements in indoor home, indoor workplace and outdoor home. The estimated NO$_2$ measurements were significantly correlated with measured personal exposures(r=0.69, N=122). For the difference between measured and estimated NO$_2$ exposures by multiple regression analysis showed that NO$_2$ concentrations in near workplace and other outdoors of no NO$_2$ measurements affected the personal NO$_2$ exposures(p=0.023).

• 응용통계연구
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• 제35권6호
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• pp.725-737
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• 2022

통계적 공정 모니터링에서 관리 상태일 때 품질 특성치의 모수값은 하나의 값으로 지정하는 경우가 대부분이다. 그러나 관리 상태로부터 공정 모수의 작은 변화는 실제적으로 크게 중요하지 않은 경우, 품질 특성치의 모수 영역은 관리 상태, 무관심, 그리고 이상 상태의 세 영역으로 구성될 수 있다. 이 논문에서는 3개의 모수 영역이 있는 공정에 적용할 수 있는 두 가지 지수가중 이동평균(exponentially weighted moving average; EWMA) 관리도 절차를 제안하고, 제안된 절차의 성능을 Shewhart 관리도 및 누적합(cumulative sum; CUSUM) 관리도와 비교하여 그 효율을 평가하였다.

• Journal of the Korean Statistical Society
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• 제18권2호
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• pp.135-148
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• 1989

Cumulative sum schemes based on a weighted score are considered for controlling the mean of a continuous production process; in which both the one-sided and two-sided schemes are proposed. The average run lengths and the run length distributions for the proposed schemes are obtained by the Markov chain approach. Comparisons by the average run length show that the proposed schemes perform nearly as well as the standard cumulative sum schemes in detecting changes in the process mean. Comparisons of the one-sided schemes by the run length distribution are also presented.