• Proceedings of the Korean Information Science Society Conference
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• 2011.06c
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• pp.443-446
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• 2011

본 연구는 컴퓨터 단층촬영 영상 (CT, Computed Tomography Image)에서 치열궁 (Dental Arch)을 자동으로 검출하는 기법을 제안한다. 제안된 기법에서는 3차원 컴퓨터 단층촬영 영상을 입력 받고 영역 확장법을 이용하여 하악을 분할 한 후 하악의 단면에서 전체적인 치아의 영역을 분할을 한다. 치아의 영역에서 세선화 작업을 거친 후 곡선 정합법을 이용하여 최종 치열궁을 검출한다. 실험 데이터로 두개골 컴퓨터 단층 촬영 데이터를 사용하였다. 본 연구는 치과 영상 데이터로부터 파노라마 영상을 얻는데 이용 될 수 있고 치과 분야의 질병 진단 및 진찰에 이용될 것으로 기대된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.642-653
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• 2008

This study deals with modeling of head-related transfer functions(HRTFs) using principal components analysis(PCA) in the time and frequency domains. Four PCA models based on head-related impulse responses(HRIRs), complex-valued HRTFs, augmented HRTFs, and log-magnitudes of HRTFs are investigated. The objective of this study is to compare modeling performances of the PCA models in the least-squares sense and to show the theoretical relationship between the PCA models. In terms of the number of principal components needed for modeling, the PCA model based on HRIR or augmented HRTFs showed more efficient modeling performance than the PCA model based on complex-valued HRTFs. The PCA model based on HRIRs in the time domain and that based on augmented HRTFs in the frequency domain are shown to be theoretically equivalent. Modeling performance of the PCA model based on log-magnitudes of HRTFs cannot be compared with that of other PCA models because the PCA model deals with log-scaled magnitude components only, whereas the other PCA models consider both magnitude and phase components in linear scale.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.381-390
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• 2001

In this paper, a new improved crack analysis technique by Element-Free Galerkin(EFG) method is proposed, in which the singularity and the discontinuity of the crack successfully described by adding enrichment terms containing a singular basis function to the standard EFG approximation and a discontinuity function implemented in constructing the shape function across the crack surface. The standard EFG method requires considerable addition of nodes or modification of the model. In addition, the proposed method significantly decreases the size of system of equation compared to the previous enriched EFG method by using localized enrichment region near the crack tip. Numerical example show the improvement and th effectiveness of the previous method.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2017.10a
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• pp.16-18
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• 2017

컴퓨터 기술이 발전함에 따라 디지털 게임 속 가상경관은 보다 정교해지고 있으며, 설계 및 구현 과정에서 고려를 요구하는 요소들이 증가하고 있다. 하지만 여태 가상경관 설계를 위한 정형화된 설계 방법론도 전무한 관계로, 디자이너들은 비효율적인 설계 과정을 거치며 동시에 질적으로도 만족스럽지 못한 결과물을 구축하고 있다. Ian McHarg의 도면 중첩법은 레이어 단위로 설계 고려요소를 정리하여 설계를 진행하기에, 설계에 고려할 요소들을 체계적으로 종합하는 디자인의 진행이 가능하다. 이에 본 연구에서는 도면 중첩법을 활용한 가상경관 설계 방법론을 구축하였다. 이를 위해서 우선 가상경관의 공간적 특수성에 따라 분류를 진행하는 분류 방법론을 문헌 조사를 통해 파악하여, 이들을 각각의 레이어로 조직하였다. 그리고 설계 영역으로서의 가상경관과 실공간의 차이점을 파악하여 이들을 기반으로 한 가상경관 설계 방법론을 구축하였다. 마지막으로 프로토콜 분석방법론과 공간 구성요소의 비교분석을 통하여 본 연구에서 구축한 설계 방법론의 유효성을 검증하였다. 검증 결과, 본 설계 방법론은 디자이너들의 작업 시간을 22% 이상 줄일 수 있었으며, 동시에 작품의 질을 향상시킬 수 있었다. 향후 본 설계 방법론은 디지털 게임을 비롯한 가상경관 설계 및 구현의 영역에서 활발한 활용을 기대할 수 있을 수 있으며, 나아가 가상경관을 조경 설계의 한 영역으로써 확장이 가능할 것임을 시사한다.

• Journal of Information Management
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• v.43 no.3
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• pp.79-95
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• 2012

This study is designed for library classification of the tourism. Contents studies are summarized as follows. First, an analysis of the current status of classification and items by a key work 'tourism' in KDC, NDC, DDC, UDC, and LCC which are main library classification tables today indicates that they are too limited to travelling and tourism, tourism policy, and tourist attractions etc. Second, we divided areas studies newly based on the theoretical books in order to extract the classification items of the tourism field, and comparatively analyzed main library classification systems today. We divided basic categories of the classification items into four including tourism general, tourists, tourism attraction, tourism media. Third, a new classification was designed for library classification of the tourism field. Basically, the tourism field was assigned to the main four items and the classification items which were weighted or scattered were adjusted.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.477-487
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• 2000

When volume data is visualized by the ray casting method, the color value of each pixel in the image is obtained by composing the color contributions of the sample points that lie on the ray cast from the pixel point. In most ray tracing methods including Levoy's classical method, the color composition is formulated as a summation of the color contributions of the discrete sample points. However, the more precise color composition is formulated as differential equations over the color contributions of the continuous sample points. The discrete formulation is used, because analytical solutions to the continuous formulations are hard to find. In this paper, however, we have discovered a semi-analytical solution to the continuous formulation of a typical ray tracing of volume data. We have applied both Levoy's method and ours to the same set of data, and compared the visual quality of both results. The comparison shows that our method produces a more fine-grained visualization of volume data.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.95-105
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• 1988

The dynamic characteristics of a tennis racket were identified by experimental modal analysis and the sweet spot due to these was calculated. A tennis racket was selected as a model reference and modal parameters of the racket were estimated from the transfer function measured by experiment. The transfer function was reconstructed by the modified modal parameters on the assumption that the racket was locally modified, for example, a change in the material of the frame and the attachment of a damping material to the grip. The change of the dynamic characteristics, especially natural frequency and magnitude of the second and the third vibrational modes, were evaluated from the reconstructed transfer function. The change of the sweet spot due to the modified modal parameters was estimated and visualized through computer graphic simulation by the criterion of the sweet spot measured before structural modification. The modal parameters for improvement of the dynamic characteristics.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.69-72
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• 2000

본 논문에서는 비선형 확장 칼만 필터(Nonlinear Extended Kalman Filter)를 이용한 강인한 스테레오 정합 알고리즘을 제안한다. 기존의 스테레오 정합 알고리즘은 변이를 구할 때 좌, 우 영상을 화소별로 비교하여 검색영역을 모두 검색하였으나 제안된 알고리즘은 비선형 확장 칼만 필터를 통해 변이를 예측하고, 예측된 변이에 대한 좌, 우 영상값을 비교하는 과정을 반복적으로 수행함으로써 단지 몇 번의 검색을 통해 변이를 구하게 된다. 그리고, 양선형 보간법(bilinear interpolation)을 이용해 주위 화소들의 영향을 고려하여 예측된 변이에 대한 좌, 우 영상값을 비교함으로써 강인한 스테레오 정합의 결과를 얻을 수 있다. 제안된 알고리즘을 수행한 결과 본 알고리즘이 우수한 정합 성능을 가짐을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.51-58
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• 2005

This paper proposes an efficient algorithm for extracting a tumor region from an breast ultrasound volume image by using rate-distortion (R-D) based seeded region growing. In the proposed algorithm the rate and the distortion represent the roughness of the contour and the dissimilarity of pixels in a region, respectively. Staring from an initial seed region set in each cutting plane of a volume, a pair of the seed region and one of adjacent regions whose R-D cost is minimal is searched and then they are merged into a new updated seed region. This procedure is recursively performed until the averaged R-D cost values per the number of contour pixels in the seed region becomes maxim. As a result, the final seed region has good pixel homogeneity and a much smooth contour. Finally, the tumor volume is extracted using the contours of the final seed regions in all the cutting planes. Experimental results show that the averaged error rate of the proposed method is shown to be below 4%.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.1
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• pp.38-43
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• 1993

A Hybrid Finite Element Method(HFEM) is applied to solve the electrormagnetic scattering from multi-layered dielectric cylinders. An unbounde region is divided into local boundary regions where a practical differential equation solution is obtained, with the remaining unbounded region represented by a boundary integral equation. If sources, media inhomogeneities, and anisotropies are local, a surgace may be defined to enclose them. Therefore the integral region so defined is bounded, and differential techniques may be used there. Also, in the re- maining unbounded region a boundary integral equation may be formulated using only a simple free - space green's function. Therefore, The local boundary is represented by a boundary - value problem with boundary conditions and solved by the finite element method. The advantage of the proposed method is simple and efficient in the work of electromagnetic scattering. The validity of the results have been verified by comparing results of other method(boundary element method). Examples has been presented to calculate the scattered fields of lossy dielectric cylinders of arbitray cross section.