• 한국통신학회논문지
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• 제29권1C호
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• pp.45-49
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• 2004

본 논문은 수정된 이방성 확산 펄터를 이용한 영상 개선 방법을 제안하였다. 이를 위하여 최소 신뢰 스케일을 기반으로 하는 센서 잡음 추정과 스케일 스페이스 방법을 도입하였다. 이때 이방성 필터는 구해진 임계값 함수와 국부 기울기에 의해 수정되었다. 모의 실험을 통해 제안한 방법이 평탄 영역에서의 잡음을 거의 증폭시키지 않으면서도 뛰어난 에지 향상을 보임을 증명할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.233-238
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• 2010

A two-dimensional laminar flow past a vertical plate in a microchannel is investigated. At far upstream and downstream from the plate in the microchannel, the plane Poiseuille flow exists. The Stokes flow for this microchannel is investigated analytically and then the laminar flow by numerical method. For the Stokes flow analysis, the method of eigenfunction expansion is used. From the results, the streamline pattern and the pressure distribution are plotted, and the additional pressure drop induced by the plate and the force exerted on the plate are calculated as functions of the length of the plate. For the laminar flow, finite difference method (FDM) is used to obtain the vorticity and the stream function. When the Reynolds number exceeds a critical value, a pair of viscous eddies appears behind the plate.

• 대한기계학회논문집A
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• 제20권10호
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• pp.3408-3414
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• 1996

This paper investigated plane strain stress intensity factors caused by thermal impact on a center-crack strip. The crack was aligned perpendicularly to the strip boundary. The problem was analysed by determining the dislocation density function in the singular integral equations formulated by the dislocation theory. Under the abrupt temperature change along the edge, the center crack behaved as a mode I crack due to the symmetric geometry. The value of maximum stress intensity factor monotonically increased until the ratio of dimensionless crack length approached to about 0.3, followed by gradual decrease. As a result, a critical corresponding crack length was determined.

• 대한전자공학회논문지
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• 제8권2호
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• pp.1-5
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• 1971

금박막의 저항을 두께와 온도(300。∼420。k)의 함수로써 측정하였다. 본논문에서는 상기의 측정결과를 Sondheimer와 Neugebauer가 제시한 이론에 따라 해석하였으며 금박막의 두께가 약 45Å일때 저항온도계수가 영이 되며 그 임계두께가 약 60Å됨을 밝혔다.

• 한국세라믹학회지
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• 제30권1호
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• pp.78-84
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• 1993

In PMN-pyrochlore phase mixtures, dielectric constant was measured as a function of the volume fraction of pyrochlore phase and considered with general effective media(GEM) equation. For the application of GEM equation to this system, the critical volume fraction(Vc) where connectivity between the perovskite PMN and pyrochlore phase changed from 0-3 to 3-3, was determined based on the each particle size ratio of two phases with microstructural observation. And then the t value was determined from modified percolation powder-law dependence ( K-Kc (V-Vc)t). In the case of applying such values of t and Vc to the GEM equation, which provided a reasonable fit to the measured dielectric constant within the experimental error range.

• Kyungpook Mathematical Journal
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• 제50권2호
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• pp.255-266
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• 2010

We consider a delayed predator-prey system with Holling II functional response. Firstly, the paper considers the stability and local Hopf bifurcation for a delayed prey-predator model using the basic theorem on zeros of general transcendental function, which was established by Cook etc.. Secondly, special attention is paid to the global existence of periodic solutions bifurcating from Hopf bifurcations. By using a global Hopf bifurcation result due to Wu, we show that the local Hopf bifurcation implies the global Hopf bifurcation after the second critical value of delay. Finally, several numerical simulations supporting the theoretical analysis are given.

• 한국IT서비스학회지
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• 제7권3호
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• pp.199-214
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• 2008

Unlike physical goods, service consists of a chain of activities that allow the service to function effectively. In order to enhance customer experiences, service providers should innovate service processes. Service innovation refers to new or considerably changed service processes that deliver added value to the customers. Unfortunately, many of the activities are invisible to both service providers and consumers. In terms of service innovation, service visualization is very critical. When we visualize the current service process, we can identify its problems. This study suggests service blueprinting as a service innovation methodology. In order to demonstrate the usage of the methodology, this study examines departure/arrival services at the airport.

• 인문언어
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• 제1권1호
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• pp.195-217
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• 2001

According to John Crowe Ransom, "the poem is a loose logical structure with an irrelevant local texture." As is implied in the opposition between "structure" and "texture," Ransom′s is a dualistic, that is, non-organic, theory of poetry, in which the poem′s sound does not have any expressive function while its figurative language always goes beyond the realm of abstract meaning and celebrates the ontological density of the world. His theory relies heavily upon a series of oppositions-poetry and prose, art and science, concrete and universal, artistic and utilitarian, to name only a few-in order to uphold the humanistic value of poetry ("poetry as knowledge"). There is, however, a sense that his theoretical consistency derives from a determined refusal to see the blurry borderline between the oppositions. It is more or less easy to point out where Ransom′s theory falters, but more critical efforts should be made to probe into the personal and cultural significance of his persistent dualistic viewpoint. For Ransom the southerner, life demands the precarious balance between the oppositions as the very precondition for its existence and his dualism represents a way to understand man′s fallen state at the realistic level.

• 한국해양공학회지
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• 제13권2호통권32호
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• pp.129-137
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• 1999

The time of the onset of double-diffusive convection in time-dependent, nonlinear concentration fields is investigated theoretically. The initially quiescent horizontal fluid layer with a uniform temperature gradient experiences a sudden concentration change from below, but its stable thermal stratification affects concentration effects in such way to invoke convective motion. The related stability analysis, including Soret effect, is conducted on the basis of the propagation theory. Under the linear stability theory the concentration penetration depth is used as a length scaling factor, and the similarity transform for the linearized perturbation equations. The newlly obtained stability equations are solved numerically. The resulting critical time to mark the onset of regular cells are obtained as a function of the thermal Rayleigh number, the solute Rayleigh number, and the Soret effect coefficient. For a certain value of the Soret effect coefficient, the stable thermal gradient promote double-diffusive convective motion.

• 전기학회논문지
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• 제62권1호
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• pp.95-100
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• 2013

This paper presents a new state feedback control approach for communication networks based control systems in which control input and output observation time-delay natures are generally occurred in practice. We first establish a generic state feedback control framework based on well-known linear system theory. A maximum time-delay value which allows critical stability of whole control system are defined to make a positive definite Lyapunov function which is mathematically composed of controlled system states. We analytically derive its control parameters by using a steepest descent optimization method in order to guarantee a stability condition through Lyapunov theory. Computer simulation is numerically carried out for demonstrating reliability of the proposed NCS algorithm and a comparative study is accomplished to prove its superiority for which the traditional control approach for NCS is made use of under same simulation scenarios.