• 한국표면공학회지
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• 제54권2호
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• pp.62-70
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• 2021

Al2024 aluminum alloy specimens were exposed to atmospheric conditions for maximum 24 months and analyzed by electron microscopes to characterize their corrosion behavior and oxide film characteristics. As the exposure time increased from 12 months to 24 months, the number of pitting sites per 1 mm² increased from ~100 to ~200. The uniform oxidation (or non-pitting) region of the 12-month exposure specimen showed 30~120 nm thick oxide layer, whereas the 24-month exposure specimen showed 170~200 nm thick oxide with the local oxygen penetration region up to 1 ㎛ deep. There was no local corrosion area observed in the 12-month exposure specimen except pitting. However, in the 24-month exposure specimen, local oxygen penetration region was observed beneath the uniform oxide layer and near the pitting cavity. Al2024 showed two times thicker uniform oxide layer but much shallower local oxygen penetration region than Al1050, which appears to be related to low Si concentration. Further research is needed on the effects of Mg segregation near the tip of the oxygen penetration region.

• 대한전자공학회논문지SP
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• 제44권4호통권316호
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• pp.78-85
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• 2007

영역들로 구성된 영상의 국부정규화처리 알고리즘에 내재된 분할 구도를 소개한다. 이동창에서 산출되는 국부통계치에 근거한 정규화적 접근은 선형 또는 비선형함수를 발생시켜 잡음 오염된 영역들의 화소분포와 근접유사 유형을 변형한다. 현재와 정규화된 영상신호 사이의 최근접 화소 이격거리에 대하여 평균과 표준편차를 조정하고 국부통계치와 파리미터 변동을 연계하여 영역간 분할 상태를 변화시킨다. 이러한 특성에 대하여 기존의 정규화 기법들과 본 연구에서 새로 고안한 국부정규화 기법이 비교 고찰된다. 그리고 실험결과는 국부정규화처리 실현에 의한 영역분할 성능을 보였다.

• 한국콘텐츠학회논문지
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• 제16권9호
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• pp.376-385
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• 2016

본 연구는 장애인가구 추가비용의 지역별 차이를 분석하여 지역특성을 반영한 추가비용 보전 급여액 산정의 근거를 마련하는데 있다. '2011년 장애인실태조사' 와 '2011년 지방자치단체 장애인예산' 자료 결합하여 추가비용의 지역별 차이를 분석하기 위해서 집단별 평균비교분석을 실시하였다. 추가비용이 가장 높은 지역은 인천광역시였으며, 추가비용 보전이 가장 높은 지역은 서울특별시로 나타났다. 장애인 예산 비율이 가장 높은 지역은 대전광역시였으며, 장애인 1인당 예산이 가장 높은 지역은 제주특별자치도로 나타났다. 두 집단 평균비교(t-test) 결과, 추가비용 보전이 높은 집단은 추가비용 보전이 낮은 집단에 비해서 장애인 예산 비율과 장애인 1인당 예산이 높은 것으로 나타났다. 정책제언으로 첫째, 지역별 특성에 맞는 추가비용 보전 급여액의 증액 둘째, 지방자치단체의 장애인예산 및 장애인 1인당 예산 증액 셋째, 추가비용 항목에 따른 추가비용 지출 감소를 위한 대책을 마련하여야 한다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1995년도 학술대회
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• pp.83-86
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• 1995

Many image display devices allow only a limited number of colors to be simultaneously displayed. In displaying of natural color image using color palette, it is necessary to construct an optimal color palette and map each pixel of the original image to a color palette with fast. In this paper, we proposed the clustering algorithm using local region block centered one color cluster in the prequantized 3-D histogram. Cluster pairs which have the least distortion error are merged by considering distortion measure. The clustering process is continued until to obtain the desired number of colors. Same as the clustering process, original color image is mapped to palette color via a local region block centering around prequantized original color value. The proposed algorithm incorporated with a spatial activity weighting value which is smoothing region. The method produces high quality display images and considerably reduces computation time.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2004년도 추계학술발표논문집(상)
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• pp.891-894
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• 2004

This paper proposes an improved image segmentation algorithm by the watershed algorithm based on the local adaptive threshold on local minima search and the fixing threshold on label allocation. The previous watershed algorithm generates the problem of over-segmentation. The over-segmentation makes the boundary in the inaccuracy region by occurring around the object. In order to solve those problems we quantize the input color image by the vector quantization, remove noise and find the gradient image. We sorted local minima applying the local adaptive threshold on local minima search of the input color image. The simulation results show that the proposed algorithm controls over-segmentation and makes the fine boundary around segmented region applying the fixing threshold based on sorted local minima on label allocation.

• 한국정보시스템학회지:정보시스템연구
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• 제29권3호
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• pp.35-52
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• 2020

Purpose Local governments in each region actively hold local festivals for the purpose of promoting the region and revitalizing the local economy. Existing studies related to local festivals have been actively conducted in tourism and related academic fields. Empirical studies to understand the effects of latent variables on local festivals and studies to analyze the regional economic impacts of festivals occupy a large proportion. Despite of practical need, since few researches have been conducted to predict the number of visitors, one of the criteria for evaluating the performance of local festivals, this study developed a model for predicting the number of visitors through various observed variables using a machine learning algorithm and derived its implications. Design/methodology/approach For a total of 593 festivals held in 2018, 6 variables related to the region considering population size, administrative division, and accessibility, and 15 variables related to the festival such as the degree of publicity and word of mouth, invitation singer, weather and budget were set for the training data in machine learning algorithm. Since the number of visitors is a continuous numerical data, random forest, Adaboost, and linear regression that can perform regression analysis among the machine learning algorithms were used. Findings This study confirmed that a prediction of the number of visitors to local festivals is possible using a machine learning algorithm, and the possibility of using machine learning in research in the tourism and related academic fields, including the study of local festivals, was captured. From a practical point of view, the model developed in this study is used to predict the number of visitors to the festival to be held in the future, so that the festival can be evaluated in advance and the demand for related facilities, etc. can be utilized. In addition, the RReliefF rank result can be used. Considering this, it will be possible to improve the existing local festivals or refer to the planning of a new festival.

• 대한기계학회논문집B
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• 제29권2호
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• pp.279-286
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• 2005

This study presents experimental results on the heat transfer coefficients in the film boiling region of spray cooling for actual metallurgical process. In this study, the heat flux distributions of a two dimensional dilute spray impinging on a hot plate were experimentally investigated. A stainless steel block was cooled down from intial temperature of about $800^{\circ}C$ by twin fluid (air-water) flat spray. It was found from the experimental results that the heat transfer area was classified into the stagnation region and wall-flow region. In the stagnation region, the experimental data of local heat transfer coefficient was closely correlated with the local droplet-flow-rate supplied from the spray nozzle directly. Thus, the local heat transfer coefficients are in good agreement with the predicted values from the correlations proposed by our previous study. In wall-flow region, however, remarkable differences are observed between experimental data and predicted values because the number of rebound droplets increase with increasing the distance from the stagnation point.

• 한국항공운항학회지
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• 제11권2호
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• pp.33-42
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• 2003

In this paper, we propose an enhancement of the ultrasonic image for non-destructive inspection of aircraft composite materials. The ultrasonic images are corrupted by a speckle noise which has the characteristic of granular pattern noise and is in all types of coherent imaging systems, the signal independent and multiplicative noise. In this paper, we derive a filter, called the AWLF(Adaptive Window Log Filter), from the nature of the speckle. The filter is made of the MEAN Filter in the edge region and Log Filter in the flat or noise region. To make a distinction between edge and flat region, we calculate the inclination around the local window instead of computing the local statistics of pixels such as local mean ${\bar{M}}$ and standard deviation ${\sigma}_s$. According to the obtained region, edge region is performed by the mean filter and flat region by the Log filter. Performance of the proposed filter is evaluated by the Enhanced Factor$(F_e)$ and the Speckle Index(SI).

• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.123-136
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• 2004

In this paper, a combining trust region and line search algorithm for equality constrained optimization is proposed. At each iteration, we only need to solve the trust region subproblem once, when the trust region trial step can not be accepted, we switch to line search to obtain the next iteration. Hence, the difficulty of repeated solving trust region subproblem in an iterate is avoided. In order to allow the direction of negative curvature, we add second correction step in trust region step and employ nonmonotone technique in line search. The global convergence and local superlinearly rate are established under certain assumptions. Some numerical examples are given to illustrate the efficiency of the proposed algorithm.

• 대한수학회지
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• 제56권4호
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• pp.1063-1081
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• 2019

In this paper, we formulate a new local move on virtual knot diagram, called arc shift move. Further, we extend it to another local move called region arc shift defined on a region of a virtual knot diagram. We establish that these arc shift and region arc shift moves are unknotting operations by showing that any virtual knot diagram can be turned into trivial knot using arc shift (region arc shift) moves. Based upon the arc shift move and region arc shift move, we define two virtual knot invariants, arc shift number and region arc shift number respectively.