• 한국항공우주학회지
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• 제33권10호
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• pp.35-41
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• 2005

재료주축과 경사진 중앙균열을 내포하는 직방성 복합재료 내 균열문제를 해석하였다. 이 균열체에는 외부경계에서 2축방향으로 작용하는 하중을 받고 있다. 복합재료 내 초기균열의 진전각을 예측하기 위하여 수직응력비 이론을 적용하였으며, 균열진전각에 미치는 2축하중과 섬유재료주축의 영향을 분석하였다. 본 해석을 통하여 균열진전각은 수평하중에 많은 영향을 받고 있으며, 또한 균열경사각과 섬유배향각에도 큰 영향을 받음을 확인하였다.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.1-7
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• 2015

In this paper, we propose a second-order fiber flexible comb filter based on a polarization-diversity loop(PDL). The proposed filter consists of a polarization beam splitter, four half-wave plates(HWPs), and three high birefringence fiber(HBF) segments. In the previous Solc-type second-order filter based on the PDL, HBF segments were fusion-spliced with a fixed angle offset between their principal axes with each other. But, the proposed filter implemented by inserting two HWPs between three HBF segments has a great flexibility in adjusting relative angular difference between the principal axes of two adjacent HBF segments. Owing to this flexibility, second-order transmission spectra, which had a channel spacing of ~0.8nm, could be interleaved by controlling the orientation angles of four HWPs. The output transmission spectra of the proposed filter were theoretically analyzed and experimentally verified.

• 한국사회복지학
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• 제57권1호
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• pp.61-91
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• 2005

본 연구는 한국의 교육현장과 실천현장을 연결하기 위한 목적의 일환으로 한국의 사회복지실천 현장에서 우리의 사회복지사들이 실제 수행하고 있는 실천활동을 분석해 보기 위한 탐색적 연구이다. 이를 위해, 연구자는 현재 한국의 다양한 사회복지 현장에서 활동하고 있는 사회복지사들(669명의 조사 대상자 중 361명이 응답)이 가장 많이 활용하고 있는 실천기술이 무엇인가를 한국의 실천현장에 뿌리를 두고 경험적으로 조사했다. 활용도가 높은 기술 132개의 목록을 제시했으며 그 기술들 안에 존재하는 주요 기술 축 7개를 탐색적 요인분석을 통해 도출했다. 다음으로 이들 각 기술 축 안에 존재하는 하위 기술군들이 요인분석을 통해 도출되었으며, 이들 하위 기술군을 대표하는 핵심기술지표 42개가 제시되었다. 마지막으로 다양한 실천현장별로 각기 다른 실천기술 축을 확인해 분류하였다. 결과의 함의와 후속 연구를 위한 제언이 제시되었다.

• 수산경영론집
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• 제14권2호
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• pp.1-14
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• 1983

This paper considers a classification of the 88 islands located at Kyong-nam area in Korea, using by examples of 12 components of the islands. By means of principal component analysis 2 principle components were extracted, which explained a total of 73.7% of the variance. Using an eigen variable criterion (λ>1), no further principle components were discussed. Principal component 1 and 2 explained 63.4% and 10.3% of the total variance respectively, The representation of the unrelated factor scores along the first and second principal axes produced a new information with respect to the classification of the islands. Based upon the representation, 88 islands were classified into 6 groups i. e. A, B, C, D, E, and F according to similarity of the components among them in this paper. The "Group F" belongs to a miscellaneous assortment that does not fit into the logical category. category.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권8호
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• pp.500-505
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• 2003

In this paper, the method to register multiple sets of skull CT images to absolute coordinate system is proposed. Contrary to correspondence paired mapping of previous techniques, four anatomical landmark points, three coplanar points and one non-coplanar point, compose three principal axes simple and unique for efficient registration by means of rigid body transformation. Throughout the numerical simulation with added random noises, the error performances in terms of different rotation and rounding-off of landmark points, and incorrect localization of anatomical landmark and target points are quantitatively analyzed to generalize the proposed technique. Experiments using real skull CT images demonstrate the feasibility for an efficient use in clinical practice.

• 한국지진공학회논문집
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• 제9권3호
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• pp.51-58
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• 2005

최근 우리나라에서는 건축적 또는 사회적 요구로 비정형 고층 RC건물이 급증하고 있으나, 이와 같은 건물을 내진설계하는데 요구되는 지진의 방향성과 직교성을 적응하기 위한 구체적인 방법이 제시되어 있지 않아 설계자들이 설계하는데 어려움이 있다. 따라서, 본 논문에서는 우리나라에서 실제 건설된 비정형고층 RC건물을 스펙트럼해석법과 시간이력해석법에 따라 SAP2000을 사용하여 동적해석을 수행한 후, 하부골조 기둥의 설계력을 비교함으로써 주축의 설정과 지진의 방향성을 고려하는 것이 설계력에 미치는 영향, 그리고 방향성과 직교성을 모두 만족시킬 수 있는 방법에 대해 연구하였다. 연구결과 내린 결론은 다음과 같다. 1) 지진에 직각방향 전단력이 발생하지 않는 방향을 주축으로 정의하여 설계부재력을 구하면, 동적밑면전단력 보정계수가 감소하기 때문에 X, Y축을 주축으로 정하여 설계부재력 구하였을 때보다 설계부재력이 $15\%$정도 작은 값을 보여주었다. 2) 100/30법에 따라 방향성을 고려하여 구한 설계부재력은 2방향 시간이력해석결과로부터 구한 최대설계부재력보다 큰 값을 보여주어 100/30법에 따라 직교성을 고려하는 방법은 타당한 것으로 나타났으나, 시간이력해석결과에서 부재력을 나타내는 벡터$(P,\;M_y,\;and\;M_z)$ 많은 부분이 100/30법에 따라 예측한 설계부재력의 영역을 벗어났다.

• Journal of Computing Science and Engineering
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• 제6권1호
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• pp.1-11
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• 2012

Computed tomography (CT) images are widely used for the analysis of the temporal evaluation or monitoring of the progression of a disease. The follow-up examinations of CT scan images of the same patient require a 3D registration technique. In this paper, an automatic and robust registration is proposed for the rigid registration of 3D CT images. The proposed method involves two steps. Firstly, the two CT volumes are aligned based on their principal axes, and then, the alignment from the previous step is refined by the optimization of the similarity score of the image's voxel. Normalized cross correlation (NCC) is used as a similarity metric and a downhill simplex method is employed to find out the optimal score. The performance of the algorithm is evaluated on phantom images and knee synthetic CT images. By the extraction of the initial transformation parameters with principal axis of the binary volumes, the searching space to find out the parameters is reduced in the optimization step. Thus, the overall registration time is algorithmically decreased without the deterioration of the accuracy. The preliminary experimental results of the study demonstrate that the proposed method can be applied to rigid registration problems of real patient images.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권6호
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• pp.267-271
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• 2002

The Hotelling transform is based on statistical properties of an image. The principal uses of this transform are in data compression. The basic concept of the Hotelling transform is that the choice of basis vectors pointing the direction of maximum variance of the data. This property can be used for rotation normalization. Many objects of interest in pattern recognition applications can be easily standardized by performing a rotation normalization that aligns the coordinate axes with the axes of maximum variance of the pixels in the object. However, this transform can not be used to rotation normalization of color images directly. In this paper, we propose a new method for rotation normalization of color images based on the Hotelling transform. The Hotelling transform is performed to calculate basis vectors of each channel. Then the summation of vectors of all channels are processed. Rotation normalization is performed using the result of summation of vectors. Experimental results showed the proposed method can be used for rotation normalization of color images effectively.

• 한국안전학회지
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• 제31권4호
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• pp.35-41
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• 2016

In order to guarantee the process safety and prevent accidents, the deviations from normal operating conditions should be monitored and their root causes have to be identified as soon as possible. The statistical theories-based method among various fault diagnosis methods has been gaining popularity, due to simplicity and quickness. However, according to fault magnitudes, the scalar value generated by statistical methods can be changed and this point can lead to produce wrong information. To solve this difficulty, this work employs PCA (Principal Component Analysis) based method with qualitative information. In the case study of our previous study, the number of assumed faults is much smaller than that of process variables. In the case study of this study, the number of predefined faults is 19, while that of process variables is 6. It means that a fault diagnosis becomes more difficult and it is really hard to isolate a single fault with a small number of variables. The PCA model is constructed under normal operation data in order to get a loading vector and the data set of assumed faulty conditions is applied with PCA model. The significant changes on PC (Principal Components) axes are monitored with CUSUM (Cumulative Sum Control Chart) and recorded to make the information, which can be used to identify the types of fault.

• Korean Journal of Geomatics
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• 제3권2호
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• pp.141-148
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• 2004

This paper deals with the characteristics of strain pattern by using permanent GPS stations in Korea in terms of seismic activity and tectonics. Fourteen GPS stations involved in precise baseline vector solution and horizontal strain components were calculated using the differences of mean baseline from ten deily solutions during the time span of three years. The mean rate of maximum shear strain if 0.12 $\mu$/yr. The mean direction of principal axes of the compression is about $85^{\circ}$ N.