• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.109-114
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• 1996

In a linear dispersive system, the combined effect of water wave frnnsformations such as refraction, diffraction, shoaling, and reflection can be predicted by the mild-slope equation which was developed by Berkhoff (1972) using the Galerkin-eigenfunction method. In the derivation of the equation, he assumed a mild slope of the bottom $\nabla$h/kh << 1 (where $\nabla$ is the horizontal gradient operator, k is the wavenumber, and h is the water depth) and thus neglected second-order bottom effect terms proportional to O($\nabla$h)$^2$ and O($\nabla$$^2$h). (omitted)

• Journal of the Korean Mathematical Society
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• v.32 no.1
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• pp.17-31
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• 1995

A Lorentzian para-Sasakian manifold M$(\varphi, \zeta, \eta, g)$ (abr. LPS-manifold) has been defined and studied in [9] and [10]. On the other hand, para-Sasakian (abr. PS)-manifolds are special semi-cosympletic manifolds (in the sense of [2]), that is, they are endowed with an almost cosympletic 2-form $\Omega$ such that $d^{2\eta}\Omega = \psi(d^\omega$ denotes the cohomological operator [6]), where the 3-form $\psi$ is the associated Lefebvre form of $\Omega$ ([8]). If $\eta$ is exact, $\psi$ is a $d^{2\eta}$-exact form, the manifold M is called an exact Ps-manifold. Clearly, any LPS-manifold is endowed with a semi-cosymplectic structure (abr. SC-structure).

• Journal of the Korean Society of Combustion
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• v.6 no.2
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• pp.15-22
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• 2001

A pressure-based, unstructured finite volume method has been applied to couple the chemical kinetics and fluid dynamics and to capture effectively and accurately the steep gradient flame field. The pressure-velocity coupling is handled by two methodologies including the pressure-correction algorithm and the projection scheme. A stiff, operator-split projection scheme for the detailed nonequilibrium chemistry has been employed to treat the stiff reaction source terms. The conservative form of the governing equations are integrated over a cell-centered control volume with collocated storage for all transport variables. Computations using detailed chemistry and variable transport properties were performed for two laminar reacting flows: a counterflow hydrogen-air diffusion flame and a lifted methane-air triple flame. Numerical results favorably agree with measurements in terms of the detailed flame structure.

• Journal of Biomedical Engineering Research
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• v.9 no.2
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• pp.153-158
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• 1988

A three-dimensional surface is reconstructed from contour information as identified on two-dimensional computed tomographic slices. Gradient operator with curvature constraint would be applied to extract the contour automatically, and backtracking is also adopted to reduce the tracking error. The surface between the consecutive slice is efficiently reconstructed using a triangular surface tiles. Hidden surface elimination, shading and parallel projection of the reconstructed surface are provied on the display screen.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1167-1177
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• 1989

In this paper, a generalized adaptive law is proposed which uses a rational function type operator for parameter adjustment. To satisfy the passivity condition of the adaptation block, we introduce a constant feedback gain into the adaptation block. This adaptation scheme is applied to the model reference adaptive control of a continuous-time, linear time-invariant, minimum-phase system whose relative degree is 1. We prove the asymptotic stability of the output error of this adaptive system by hyperstability method. It is shown that by digital computer simulations this law can give a better output error transient response in some cases than the conventional gradient adaptive law. And the output error responses for the several types of the proposed adaptation law are examined in the presence of a kind of unmodeled dynamics.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1775-1778
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• 2003

본 논문에서는 컬러 NTGST (noise-tolerant generalized symmetry transform)를 기초로 하여 부분적인 조명 변화뿐 아니라 그림자 및 잡음이 있는 환경에서도 효과적으로 코너만을 검출할 수 있는 코너 검출자를 제안하였다. 제안한 코너 검출자는 잡음에 둔감한 NTGST를 기초로 하여 코너에 가까울수록, 두 직선 에지가 이루는 각이 작을수록 큰 값이 코너에 누적되도록 하여 코너의 정확한 위치를 검출할 수 있도록 하였다 특히 조명 변화에 둔감한 HSI 색 공간에서 색상 (hue) 성분을 강조하고 채도 (saturation) 및 휘도 (intensity) 성분을 보조적인 정보로 활용함으로써 부분적인 조명 및 그림자의 영향을 줄일 수 있도록 가중조합 벡터 미분 연산자 (weighted combination of vector gradient vector operator)를 제안 적용하여 그림자로 인한 거짓 경계선 및 거짓 코너를 제거할 수 있도록 하였다. 실험을 통하여 제안한 코너 검출 방법이 잡음 및 조명 변화에 둔감하게 효과적으로 코너를 검출함을 확인하였다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.127-132
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• 2000

Though the increment of using computer vision system, there are lots of difficulties to measure precisely because of measurement error or distortion phenomenon. Among these reasons, the distortion of edge is dominant reason which is occurred by the blurred image. So, the problem of clear judgment about image focal point is very important. We must fix the discrimination criteria which is collected by image recognition of precise focus. To solve these problems, we compare with make processing methods using image intensity gradient, laplacian, and sum -modified laplacian operator. These experimental results showed modified mask processing method is effective.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.490-495
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• 1996

Though the increment of using computer vision system in modern industry, there are lots of difficulties to measure precisely because of measurement error distortion phenomenon. Among these reasons, the distortion of edge is dominant reason which is occurred by the blurred image. The blurred image is happened when camera can not discriminate its precise focus. To calibrate and generalize distortion phenomenon is important. Thus, we must fix the discrimination criteria which is collected by image recognition of precise focus. Also, radial distortion causes an inward or outward displacement of a given image point from its ideal location. This type of distortion is mainly caused by flawed radial curvature curve of the elements. Thus, we were analyzed the distortion in terms of the changed with lens magnification.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.831-841
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• 2007

This work is to extend the elliptic operator, which has been already adopted in turbulent stress model, to fully developed turbulent buoyant channel flows with changing the orientation of the buoyancy vector to be perpendicular to the channel walls. The turbulent heat flux models based on the elliptic concept are employed and closely linked to the elliptic blending second moment closure which is used for the prediction of Reynolds stresses. In order to reflect the stable or unstable stratification conditions, the present model introduces the gradient Richardson number into the thermal to mechanical time scale ratio and model coefficients. The present model has been applied for the computation of stably and unstably stratified turbulent channel flows and the prediction results are directly compared to the DNS data.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.1-6
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• 1998

Our studies diagnose insulation degradation using the method of PD system. In analysis method of degradation, we make use of degradation information that analyzed the phase angle - PD pulse amplitude - degradation time( $\Phi$- PDA - t) pattern and phase angle- PD pulse number - degradation time( $\Phi$- PDN - t) pattern using statistical operators such as skewness(S), kurtosis(K). Secondly using statically operator such as the center of gravity (G), the gradient of the discharge distribution(C), we have analyzed for the prediction of life which we can be obtained the time, occurred of many pulse of small discharge amplitude.