• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.244-246
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• 2014

에지검출은 영상의 특징 정보를 화소값들의 밝기 변화로 취득하는 기술이며, 여러 영상처리 분야에서 전처리 과정으로 활용되고 있다. 기존의 에지 검출 방법에는 소벨(Sobel), 프리윗(Prewitt), 로버츠(Roberts) 방법 등이 있으며, 이러한 방법들은 영상의 전체 영역에서 동일한 가중치를 적용하여 처리하므로 에지검출 결과가 다소 미흡하다. 따라서 본 논문은 변형된 방향성 마스크를 적용하여 화소들의 방향 및 크기를 고려한 에지검출 알고리즘을 제안하였다.

• 대한수학회보
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• 제60권1호
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• pp.171-184
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• 2023

In this paper, we show that a complete translating soliton Σ^m in ℝⁿ for the mean curvature flow is stable with respect to weighted volume functional if Σ satisfies that the L^m norm of the second fundamental form is smaller than an explicit constant that depends only on the dimension of Σ and the Sobolev constant provided in Michael and Simon [12]. Under the same assumption, we also prove that under this upper bound, there is no non-trivial f-harmonic 1-form of L²_f on Σ. With the additional assumption that Σ is contained in an upper half-space with respect to the translating direction then it has only one end.

• 한국멀티미디어학회논문지
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• 제11권3호
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• pp.292-300
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• 2008

본 논문에서는 점진적인 화소 확장을 이용하여 영상 내에 존재하는 선분을 찾아내는 선분 추출 알고리즘을 제안한다. 본 논문에서 제안하는 선분 추출 방법에서는 기존의 선분 추출 방법인 허프 변환 기반 방법이나 선분의 그룹화 기반 방법과는 다른 접근법을 사용하였다. 영상이 입력되면 케니 테두리를 구하고, 테두리 화소 중 임의의 점을 선택하여 선분을 근사화 시킨 기본 직선을 만든 후, 선택된 점에서 임의의 반경 내에 있는 테두리 화소들을 선택한다. 직선과의 거리 오차와 기울기 각의 오차를 이용하여 선택된 화소에 가중치를 부여한다. 가중치 합 비교에 의해 선택된 화소들이 떨어져 있는지를 판별한 후, 가중치를 적용한 최소자승법에 의해 선 맞춤을 하여 선분을 구하게 된다. 제안된 알고리즘은 기존에 제안된 방법들과 결과를 비교하였으며, 계산 속도가 빠르면서 실제 존재하는 선분 추출이 가능하다는 것을 실험 결과를 통해 제시한다.

• 한국대기환경학회지
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• 제18권2호
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• pp.95-112
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• 2002

A precision analysis was conducted for the quantification of trace metal levels in airborne particulates using ICP-MS. According to our study the quantitative analysis using Whatman grade 41 filters produces more precise and representative values of metal concentrations than that using EPM 2000 filters. The mean concentration of PM 10 analyzed during 1998 ~ 2000 was 82 $\mu$g/m$^3$. The concentrations of human carcinogens such as As and Cr were 8.65 and 25.87 ng/m$^3$, respectively, while those of probable human carcinogens such as Cd and Pb were 3.13 and 219.46 ng/m$^3$, respectively. Time-weighted mean concentration, calculated using surface wind speed and direction, indicated that there were differences between metals of crustal origin and metals of anthropogenic origin. The rectorial concentrations of anthropogenic metals and PM 10 were higher for north -west sector with calm or low wind speed conditions than for any other sector with high wind speed conditions. On the contrary, the rectorial concentrations of crustal metals were high with high wind speed. In addition, the sectorial concentrations of crustal metals were more affected by south-west wind directions, which were compared with those of anthropogenic metals. The enrichment factor (EF) values of many anthropogenic metals were higher than 50, while those of crustal metals were lower than 3, respectively. The concentrations of Cr and Ni in Daejeon industrial complex area were 11 times higher than those in the background site of Kuopio in Finland, while that of Pb in the complex area was 22 times higher, respectively.

• 한국콘텐츠학회논문지
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• 제6권10호
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• pp.107-113
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• 2006

H.264의 인트라 프레임 에러복원기법은 상하좌우 인접한 블록의 픽셀을 사용하여 거리의 가중치 평균값으로 손실된 블록을 복원한다. H.264의 인트라 프레임 에러복원기법은 주변블록 픽셀의 간단한 평균값을 이용하여 복원하므로 심각한 블러링 현상이 발생하고 화질 저하의 문제를 야기한다. 이를 개선하기 위하여 본 논문에서는 주변블록의 픽셀 정보를 이용하여 손실된 블록의 주된 에지 방향을 추정하고, 통계값을 이용한 방해함수의 결과 값으로 에지 방향 기반의 보간법과 가중치 평균 보간법을 적응적으로 선택하여 복원하는 방법을 제안한다. 에지방향 기반의 보간법에서는 선택된 주된 에지방향과 상하좌우 각각의 주변블록의 에지방향들 간의 상호관계를 고려함으로써 최종적으로 최적 에지 방향을 선택하여 성능을 향상시킨다. 제안된 방법은 영상에 따라 H.264 에러복원기법보다 객관적인 화질이 $0.5{\sim}2.0dB$ 정도의 PSNR 향상을 보였다.

• Imaging Science in Dentistry
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• 제45권3호
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• pp.159-168
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• 2015

Purpose: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. Material and Methods: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo $T_1$-weighted images, fast spin-echo $T_2$-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. Results: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. Conclusion: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

• 한국실내디자인학회논문집
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• 제25권3호
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• pp.102-111
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• 2016

There are various form of public elements in modern urban space. These public elements mingle with sociocultural elements which consist of each city, determining urban environment's image. Especially, since the social value of design becomes important, the social role of public design has been emphasized as an effective value for public interest and environment. It is just about 10 years since design mind in the public sector has been made domestically. Even though domestic public design has been studied not so long, it has developed with radical change of social culture and science technology. This study targets public environment in modern dense urban space. Also, it grasps the trend of public design studies through analysing and documentary survey of the existing studies, and based on that result, aims at presenting the direction that domestic public design studies should progress. This study selected 253 theses(1989.6~2015.11) by collecting primary, secondary data about public design studies, and implemented overall meta-analysing about the trend of domestic public design studies. As a result, public design has been studied intensively in the field of design about environment, architecture, etc. The trend analyzing of study purpose and keyword has a tendency which is weighted towards exploratory study focused on suggestion and development about object and realm of public design. The trend analyzing of study area tends to study overall part of public space or public facility rather than specific area and object. The most parts of studies analyze domestic area, especially Seoul metropolitan area. Also, the study method weighted in favor of some qualitative analysis has been utilized.

• 디지털융복합연구
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• 제17권1호
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• pp.403-412
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• 2019

본 연구는 아토피피부염 발생의 시 군 구 단위별로 시공간적 변이를 분석하고, 이에 대한 주요 요인을 파악하는 것이다. 연구에 활용한 자료는 2009년~2013년까지의 지역사회건강조사와 통계청의 통계포털시스템 등에서 수집한 자료로 시 군 구 단위의 데이터베이스를 구축한 뒤, 기술통계 및 지리적 가중회귀모형을 이용하여 분석하였다. 분석결과, 지역별 아토피피부염 진단율은 5년간 지속적으로 증가하였으며, 지역 간 차이도 큰 것으로 나타났다. 아토피피부염 진단에 미치는 요인은 노인비율, 우울증 경험률, 기초생활 수급자 비율, 고위험 음주율, 담배 소매업 수, 폐수배출업소 수, 패스트푸드 음식점 업수로 나타났다. 본 연구는 아토피피부염과 관련된 지역적 특성을 고려한 보건정책에 기초 자료를 제공하고, 지역별 건강사업 우선순위 결정에 대한 정보를 제시하였다는 점에서 의의를 가진다.

• 한국재료학회지
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• 제33권2호
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• pp.54-62
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• 2023

The most comprehensive and particularly reliable method for non-destructively measuring the residual stress of the surface layer of metals is the sin²ψ method. When X-rays were used the relationship of ε_φψ-sin²ψ measured on the surface layer of the processing metal did not show linearity when the sin²ψ method was used. In this case, since the effective penetration depth changes according to the changing direction of the incident X-ray, σ_φ becomes a sin²ψ function. Since σ_φ cannot be used as a constant, the relationship in ε_φψ-sin²ψ cannot be linear. Therefore, in this paper, the orthogonal function method according to Warren's diffraction theory and the basic profile of normal distribution were synthesized, and the X-ray diffraction profile was calculated and reviewed when there was a linear strain (stress) gradient on the surface. When there is a strain gradient, the X-ray diffraction profile becomes asymmetric, and as a result, the peak position, the position of half-maximum, and the centroid position show different values. The difference between the peak position and the centroid position appeared more clearly as the strain (stress) gradient became larger, and the basic profile width was smaller. The weighted average strain enables stress analysis when there is a strain (stress) gradient, based on the strain value corresponding to the centroid position of the diffracted X-rays. At the 1/5 I_max max height of X-ray diffraction, the position where the diffracted X-ray is divided into two by drawing a straight line parallel to the background, corresponds approximately to the centroid position.

• Geomechanics and Engineering
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• 제34권3호
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• pp.267-284
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• 2023

Landslides are one of the most dangerous phenomena and natural disasters. Landslides cause many human and financial losses in most parts of the world, especially in mountainous areas. Due to the climatic conditions and topography, people in the northern and western regions of Iran live with the risk of landslides. One of the measures that can effectively reduce the possible risks of landslides and their crisis management is to identify potential areas prone to landslides through multi-criteria modeling approach. This research aims to model landslide potential area in the Oshvand watershed using a support vector machine algorithm. For this purpose, evidence maps of seven effective factors in the occurrence of landslides namely slope, slope direction, height, distance from the fault, the density of waterways, rainfall, and geology, were prepared. The maps were generated and weighted using the continuous fuzzification method and logistic functions, resulting values in zero and one range as weights. The weighted maps were then combined using the support vector machine algorithm. For the training and testing of the machine, 81 slippery ground points and 81 non-sliding points were used. Modeling procedure was done using four linear, polynomial, Gaussian, and sigmoid kernels. The efficiency of each model was compared using the area under the receiver operating characteristic curve; the root means square error, and the correlation coefficient . Finally, the landslide potential model that was obtained using Gaussian's kernel was selected as the best one for susceptibility of landslides in the Oshvand watershed.