• 한국정밀공학회지
• /
• 제20권2호
• /
• pp.40-49
• /
• 2003

Ferrule is widely used as fiber optic connecters. In fiber-optic communications. the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin. pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule centers are investigated in the case where the ferrule is chucked with the cone-shaped center pins and bail centers, With homogeneous coordinate transformation and numerical analysis, the obtained results are as follows: In the case of cone-type center, the alignment errors between center pins alone do not affect the rotation accuracy of ferrule. The alignment errors between center holes cause sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers is proportional to the center pin angle. In the case of ball-type center, the displacements of ferrule centers has similar pattern as cone-type center, and the alignment errors art proportional to ball diameters.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권2호
• /
• pp.883-900
• /
• 2017

In this paper block based blind secure gray image watermarking scheme based on discrete wavelet transform and singular value decomposition is proposed. In devising the proposed scheme, security is given high importance along with other two requirements: robustness and imperceptibility. The use of discrete wavelet transform not only improves robustness but the selection of bands with high tolerance towards noise caused an improvement in terms of imperceptibility. The robustness further improved due to the involvement of singular vectors along with singular values in watermark embedding and extraction process. Finally, to achieve security, the selected DWT band is decomposed into smaller blocks and random blocks are chosen for modification. Furthermore, the elements of left and right singular vectors of selected blocks are chosen based on their dependence upon each other for watermark embedding. Various experiments using different images as host and watermark were conducted to examine and validate the proposed technique. Additionally, the proposed technique is tested against various attacks like compression, affine transformation, cropping, translation, X shearing, scaling, Y shearing, filtering, blurring, different kinds of noises, histogram equalization, rotation, etc. Lastly, the proposed technique is compared with state-of-the-art watermarking techniques and their comparison shows significant improvement of proposed scheme over existing techniques.

• 천문학회지
• /
• 제41권3호
• /
• pp.77-81
• /
• 2008

As a continuation of a previous work by Park et al. (2006), we have developed a two-element radio interferometer that can measure both the phase and amplitude of a visibility function. Two small radio telescopes with diameters of 2.3 m are used as before, but this time an external reference oscillator is shared by the two telescopes so that the local oscillator frequencies are identical. We do not use a hardware correlator; instead we record signals from the two telescopes onto a PC and then perform software correlation. Complex visibilities are obtained toward the sun at ${\lambda}\;=\;21\;cm$, for 24 baselines with the use of the earth rotation and positional changes of one element, where the maximum baseline length projected onto UV plane is ${\sim}\;90{\lambda}$. As expected, the visibility amplitude decreases with the baseline length, while the phase is almost constant. The image obtained by the Fourier transformation of the visibility function nicely delineates the sun, which is barely resolved due to the limited baseline length. The experiment demonstrates that this system can be used as a "toy" interferometer at least for the education of (under)graduate students.

• 한국전산구조공학회논문집
• /
• 제13권2호
• /
• pp.209-220
• /
• 2000

보강된 판 및 쉘구조의 기하학적 비선형해석을 수행하기 위하여, total lagrangian formulation에 근거한 증분 평형방정식을 적용하고, 강도행렬 산정시 회전각의 2차항을 포함시켜 기하학적 비선형 해석시 해의 수렴성을 향상시켰으며, 보강된 쉘 구조의 해석시 보강재를 쉘 요소로 모델링하고 주부재와 보강재의 연결점에서 일반적인 변환관계를 이용하였다. 등매개 쉘 유한요소의 단점인 locking 현상을 극복하기 위하여 가정 변형률장을 적용하여 감차적분 또는 선택적분시 나타날 수 있는 제로 에너지 모드를 제거하였다. 수치해석 예제를 통하여 가정 변형률장에 근거한 쉘유한요소에 대한 효율성 및 적용성을 확인하였다.

• International Journal of CAD/CAM
• /
• 제9권1호
• /
• pp.37-46
• /
• 2010

Existing methods for the registration of blurred images are efficient for the artificially blurred images or a planar registration, but not suitable for the naturally blurred images existing in the real image mosaic process. In this paper, we attempt to resolve this problem and propose a method for a distortion-free stitching of naturally blurred images for image mosaic. It adopts a multi-resolution and robust feature based inter-layer mosaic together. In each layer, Harris corner detector is chosen to effectively detect features and RANSAC is used to find reliable matches for further calibration as well as an initial homography as the initial motion of next layer. Simplex and subspace trust region methods are used consequently to estimate the stable focal length and rotation matrix through the transformation property of feature matches. In order to stitch multiple images together, an iterative registration strategy is also adopted to estimate the focal length of each image. Experimental results demonstrate the performance of the proposed method.

• 한국태양에너지학회 논문집
• /
• 제36권3호
• /
• pp.9-16
• /
• 2016

This paper discusses a refined model for investigating the micro-mechanical behavior of beam-like structures, which are composed of various elastic moduli and complex geometries varying through the cross-section directions and are also periodically-repeated and heterogeneous along the axial direction. Following the previous work (Lee and Yu, 2011), the original three-dimensional static problem is first formulated in a unified and compact form using the concept of decomposition of the rotation tensor. Taking advantage of the smallness of the cross-sectional dimension-to-length parameter and the micro-to-macro heterogeneity, while also performing homogenization along the dimensional reduction simultaneously, the variational asymptotic method is rigorously used to construct a total energy function, which is asymptotically correct up to the second order. Furthermore, through the transformation procedure based on the pure kinematic relations and the linearized equilibrium equations, a generalized Timoshenko model is systematically established. For the purpose of dealing with realistic and complex geometries and constituent materials at the microscopic level, this present approach is incorporated into a commercial analysis package. A few examples available in literature are used to demonstrate the consistency and efficiency of this proposed model, especially for the structures, in which the effects of transverse shear deformations are significant.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2002년도 춘계종합학술대회
• /
• pp.585-589
• /
• 2002

본 논문에서는 효과적인 특징 추출을 기반으로 한 계층적인 검색 시스템을 제안한다. 조명 변화 및 영상의 이동과 크기 변화 그리고 회전과 같은 기하학적 변형에도 강한 속성을 가지는 영상 검색을 할 수 있도록 사용자의 질의 영상을 웨이블릿(Wavelet) 변환을 한 후 동일한 크기의 부영역으로 나누어진 저대역 부밴드에서 칼라의 특징으로 추출된 모멘트와 질감 특징인 GLCM(Gray Level Co-occurrence Matrix)의 Contrast를 사용해 유사 영상들의 1차 분류 과정을 거친다. 보다 정확한 검색을 수행하기 위해 1차 분류된 후보 영상들에 대해 고대역 부밴드에서 추출된 수평, 수직, 대각선 방향별 에너지(Energy)를 기반으로 한 에너지의 상대적인 성분 분포의 비교가 수행됨으로써 효율적인 영상 검색 결과를 보였다.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2000년도 추계학술발표논문집 (하)
• /
• pp.1345-1348
• /
• 2000

Computers and communication technologies have been brought tremendous change to various aspects of an ever-fast changing world at present. Particularly, the use of internet and cyberspace is widespread in every comer of our life. We developed a cyber shell museum using an animation technology. It was developed for educational purposes, and accessible through the world wide web of internet. Cyber shell museum is consisted of five compartment including rare shells, marvelous shells, shell of the world, the shell of Korea and its story of shells. The database contains the pictures and related information of the shell and it implies not only animation display but also text information. The files of database were classified depending on the species, genus, family, order, and class and division of the shell. Picture of shells is displayed and user may reach the image and virtual view information by clicking through the object displayed. This provides multiple techniques to user may manipulate, visualize and interact with image on the web. And every such transformation as translation, rotation, and scaling can be applied in the picture interactively for the convenient and effective viewing.

• 한국의류산업학회지
• /
• 제15권3호
• /
• pp.325-335
• /
• 2013

This work develops a motif design integrated with geometrical patterns in traditional ddeoksal and that can be applied to a scarf design so that traditional elements unique to Korean culture can be developed further for a modern application to various design fields. For the research method, literature reviews on op art and traditional ddeoksal were conducted with Adobe Illustrator CS3 and Adobe Photoshop CS3. As for the motif combination, such applications were taken as five pieces from the works of Victor Vasarely and some traditional ddeoksal shapes such as oblique line pattern, taegeuk pattern, and geometrical pattern. Abstract and geometrical images were borrowed from op art and ddeoksal for image expression. The total number of works selected was eleven. To realize the applied scarf design, a motif layout was performed with the scarf center or rim highlighted so that each design feature could be remarkable based on the motif combination. With the function of scaling, rotation, opacity control, filtering effect, the changed images were shown through motif distortion. In addition, this work applies a single combined motif to products for a possible transformation into handkerchiefs and boutique scarfs in the case of smaller sized scarfs.

• 한국기계가공학회지
• /
• 제9권5호
• /
• pp.20-27
• /
• 2010

In this study, we improved problems in the existing product by PARKER and developed the swivel valve tube couplers that can be produced by a low price in Korea. The major development was that a modulized production method was implemented by introducing a part assembling method that uses a cocking jig, and the production cost was reduced by operating the production process more simply than that of PARKER. Also, it was possible to avoid the patient registered by PARKER through the differences in the number of grooving processes and the type of o-ring. In the results of the rotation test by varying its application angle after installing it to a vehicle, it was verified that the structure proposed in this study can endure the eccentric torque and transformation pressure for various angles that have been considered as the problem in the existing fixed tube couplers. In addition, the structure was developed to adopt the problem that represents differences in the installation position of an air tank or the length and direction of hoses according to the type of vehicles produced in vehicle manufacturers. Furthermore, it was possible to verify that the product developed in this study was more excellent than that of PARKER through comparing the performance according to the Federal Motor Vehicle Safety Standard.