• 한국광학회지
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• 제8권3호
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• pp.199-203
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• 1997

안구표면과 같은 미세구면의 변위를 알아내기 위하여 Twyman-Green 간섭계를 이용하였으며 반송무늬(carrier fringe)를 형성시켜 푸리에 변환법으로 미세구면의 변위분포를 측정하였다. 기준위치에서 일정한 반송무늬가 형성되도록 한 후 구면이 변화할 때 반송무늬의 변화방향을 관측하였으며, 반송무늬의 변화방향에 의해 구면의 변화방향을 알아내었다. 푸리에 변환법(Fourier transform method)을 이용하여 CCD카메라에서 받아들여진 한 장의 간섭무늬로부터 위상분포를 얻어내고 구면의 변위 분포를 계산하였다. 공간주파수 영역에서 변위에 대한 정보를 분리함으로써 간섭무늬의 배경분포 및 잡음을 제거하였으며, 구면의 변위에 대한 3차원 분포를 이론적인 계산값의 측정오차가 .lambda./10 이내에서 얻어내었다.

• 전자공학회논문지 IE
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• 제46권3호
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• pp.19-25
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• 2009

본 논문에서는 구 좌표계를 이용하여 위치에 대한 불변 특징을 획득할 수 있는 문자 특징 추출 방법을 제시하고자 하였으며, 획득한 문자 특징 정보를 이용하여 해당 문자를 영상 중심으로 이동시켜 인식이 가능하도록 하는 시스템을 제안하고자 하였다. 또한 영상 중심에 이동시키는 방법으로 좌표 평균값에 의한 중심 이동법을 사용하여 인식에 필요한 시스템을 구현하였으며, 추출된 특징에 대하여 특징의 이질도를 검사하여, 각 특징의 이질도가 평균 78.14% 이상의 결과를 얻었다. 본 논문에서는 문자 인식을 위하여 구 좌표계를 이용한 문자 특징 추출 방법을 제시하였으며, 무게 중심법을 이용하여 문자를 중앙에 처리한 상태에서 이질도를 알아봄으로서 인식 가능한 형태의 문자 형태를 얻을 수 있는 가능성을 제시하였다.

• Coupled systems mechanics
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• 제9권4호
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• pp.325-342
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• 2020

A mathematical model of electro-thermoelasticity subjected to memory-dependent derivative (MDD) heat conduction law is applied to a one-dimensional problem of a thermoelectric spherical cavity exposed to a warm stun that is an element of time in the presence of a uniform magnetic field. Utilizing Laplace transform as an instrument, the issue has been fathomed logically within the changed space. Numerical inversion of the Laplace transform is carried for the considered distributions and represented graphically. Some comparisons are shown in the figures to estimate the effects of MDD parameters and thermoelectric properties on the behavior of all considered fields.

• Korean Chemical Engineering Research
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• 제57권5호
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• pp.652-665
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• 2019

Analytical solutions of the reactant concentration inside porous spherical catalytic particles were obtained from unsteady reaction-diffusion equation by applying eigenfunction expansion method. Various surface concentrations as exponentially decaying or oscillating function were considered as boundary conditions to solve the unsteady partial differential equation as a function of radial distance and time. Dirac delta function was also used for the instantaneous injection of the reactant as the surface boundary condition to calculate average reactant concentration inside the particles as a function of time by Laplace transform. Besides spherical morphology, other geometries of particles, such as cylinder or slab, were considered to obtain the solution of the reaction-diffusion equation, and the results were compared with the solution in spherical coordinate. The concentration inside the particles based on calculation was compared with the bulk concentration of the reactant molecules measured by photocatalytic decomposition as a function of time.

• Archives of Pharmacal Research
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• 제7권2호
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• pp.145-151
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• 1984

A novel agglomeration technique, termed "Spherical Crystallization Process", which can transform directly the fine crystals produced in the crystallization or the reaction process into a spherical shape was developed. By this technique, needle like crystals such as salicylic acid were transformed into free flowing and directly compressible agglomerates. Sphericaly agglomerated aminophyline crystals were obtained directly from the reaction system, which could reduce the preparation processes, e. g. synthesis, crystallization and agglomeration, into only one step. Sodium theophyline monohydrate agglomerates were prepared by salting out, the rate process of which was described by a first order kinetics. Agglomerated crystals of ndw complex of indo-methacin-mepirizole were prepare with this technique; an improved therapeutic effect of the resultant crystals was expected. expected.

• 한국분무공학회지
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• 제6권1호
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• pp.35-43
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• 2001

Previous studies on image processing techniques for panicle size measurement usually have focused on a single panicle or weakly overlapped particles. In the present work, the image processing algorithm for particle size measurement has been improved to process heavily-overlapped spherical-particle images. The algorithm consists of two steps; detection of boundaries which separate the images of the overlapped panicles from the background and the panicle identification process. For the first step, Sobel operator (using gray-level gradient) and the thinning process was adopted, and compared with the gray-level thresholding method that has been widely adopted. In the second, Hough transform was used. Hough transform is the detection algorithm of parametric curves such as straight lines or circles which can be described by several parameters. To reduce the measurement error, the process of finding the true center was added. The improved algorithm was tested by processing an image frame which contains heavily overlapped spherical panicles. The results showed that both the performances of detecting the overlapped images and separating the panicle from them were improved.

• 조명전기설비학회논문지
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• 제29권9호
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• pp.14-22
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• 2015

TIn this paper, a centering method for an unfocused input character using the spherical domain system and the centering character to use the shift invariant feature for the recognition system is proposed. A system for recognition is implemented using the centroid method with coordinate average values, and the results of an above 78.14% average differential ratio for the character features were obtained. It is possible to extract the shift invariant feature using spherical transformation similar to the human eyeball. The proposed method, which is feature extraction using spherical coordinate transform and transformed extracted data, makes it possible to move the character to the center position of the input plane. Both digital and optical technologies are mixed using a spherical coordinate similar to the 3 dimensional human eyeball for the 2 dimensional plane format. In this paper, a centering character feature using the spherical domain is proposed for character recognition, and possibilities for the recognized possible character shape as well as calculating the differential ratio of the centered character using a centroid method are suggested.

• 한국전자파학회논문지
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• 제23권4호
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• pp.515-523
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• 2012

본 논문에서는 구형 유전체 위에 있는 구형 패치의 전파 특성으로서 공진 특성과 방사 특성을 분석하였다. 공진 주파수와 Q를 계산하여 특정 모드의 공진 특성을 해석하였으며, 원거리에서의 전기장을 계산하여 방사 특성을 해석하였다. 구형 유전체의 해석을 위해 스펙트럴 영역 해석법(spectral domain analysis method)를 적용하였으며, Vector Legendre transform pair와 Galerkin's method를 이용하여 스펙트럴 영역으로 변환한 후 대수식으로 정리하여 효율적인 계산을 할 수 있었으며, 이를 통해 구형 패치의 반지름이나 곡률, 유전체의 특성이 구형 패치의 특성에 미치는 영향을 해석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.85-89
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• 2001

The problem of the transient interaction of a plane acoustic shock wave which has an infinitely steep wave front with a cylindrical or spherical elastic shell has been studied analytically from early fifties based on the integral transform and series solution techniques. Huang adopted an inverse Laplace transform, and used a finite number of terms of the infinite series expansion of the equations for the shells. In the 1990s, the results have been used by many authors for validation of computer codes. The object of this paper is to discuss the interaction between a moving source and submerged spherical shells. Since the center of source is moving the first contact location between the waves and shell changes depending on the source velocity and distance. These are considered in the analysis. Furthermore, constant source strength and decreasing strength are considered in the analysis. Radial velocities at several locations on the structure are obtained and the results are discussed.

• 지구물리와물리탐사
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• 제15권4호
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• pp.245-248
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• 2012

일정고도에서 얻어진 중력 혹은 자력탐사자료에 대하여 보다 높은 고도에서의 값으로 연속하여 구하는 방법, 즉 상향연속의 경우 2차원 푸리에변환을 사용할 수 있다. 기존의 상향연속 방법에서는 지구의 곡률이 고려되지 않았으나, 지역이 수백킬로미터 이상으로 넓은 경우 곡률이 고려됨이 바람직하다. 본 연구에서는 지구의 곡률효과를 산정하는 중/자력 마당의 새로운 상향연속방법을 계발하였다.