• 대한전자공학회논문지SP
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• 제40권6호
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• pp.1-9
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• 2003

본 논문에서는 지문 영상의 컨벡스 (convex) 구조를 이용하여 특징점을 추출하는 방법을 제안하였다. 지문영상에서 융선은 일정한 방향성을 가지며 융선의 단면은 주기성이 있는 사인파로 간주할 수 있다. 사인파 신호에서 국부 최대 위치를 검출함으로써 대략적인 한 화소 단위의 융선 추출이 가능하며 사인파 신호의 볼록한 컨벡스는 융선 영역에 해당한다. 이러한 지문의 특징을 이용하여 특징점을 효과적으로 찾는 방법을 제안한다. 이 과정에서 파라미터를 없애고 계산량을 줄임으로써 다양한 환경의 시스템에 적용 가능함을 보였다.

• 자원환경지질
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• 제12권1호
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• pp.17-28
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• 1979

3차원의 sinx/x 방법을 이용하여 한반도 남부와 인접 일본해에서의 중력 자료(資料)로부터 측지학적 및 지구 물리학적으로 정량적인 해석을 시도하였다. 한반도에서 균충상태(均衝狀態)에 있는 지각(地殼)의 두께는 26km로 밝혀졌으며 이 지역에서의 isostatic gravity이상치는 평균+24.8 mgal로 나타났다. 이 결과는 지표지형(地表地形)의 보정이 덜되어 있거나 또는 지각의 두께가 정상보다 얇음을 의미한다. 또한 일반적으로 중력치의 수직성분의 편차방향이 한반도 남부지역의 지구조방향인 북북동-남남서에 수직인 것은 특기할만한 사실이다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.132-135
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• 2000

Magneto-resistances of the YBa$_2$Cu$_3$O$_{7-{\delta}}$ based coated conductors fabricated on the tilted single crystalline Ni substrates and RABiTS (rolling assisted bi-axially textured substrate) were measured under various magnetic fields. The activation energies of vortices were estimated from them by fitting equation of p = p$_o$ exp(-U(H,T)/k$_B$T). When currents flew in the rolling direction for the case of the tilted single crystalline YBCO on the RATS, the activation energies were similar to those of c-axis normal YBCO films on the SrTiO$_3$ single crystal substrates [5] and were slightly larger than those of the RABiTS coated conductors. On the contrary, for the currents flowing in the transverse direction, the magnetoresistances show double transitions in the temperature with much smaller activation energies.

• Journal of applied mathematics & informatics
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• 제38권5_6호
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• pp.375-406
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• 2020

The anti-predator factor due to fear of predator in eco- epidemiological models has a great importance and cannot be evaded. The present paper consists of a modified Lesli-Gower predator-prey model with contagious disease in the predator population only and also consider the fear effect in the prey population. Boundedness and positivity have been studied to ensure the eco-epidemiological model is well-behaved. The existence and stability conditions of all possible equilibria of the model have been studied thoroughly. Considering the fear constant as bifurcating parameter, the conditions for the existence of limit cycle under which the system admits a Hopf bifurcation are investigated. The detailed study for direction of Hopf bifurcation have been derived with the use of both the normal form and the central manifold theory. We observe that the increasing fear constant, not only reduce the prey density, but also stabilize the system from unstable to stable focus by excluding the existence of periodic solutions.

• 대한기계학회논문집B
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• 제27권7호
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• pp.867-876
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• 2003

The Lagrangian dispersion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Four points Hermite interpolation in the homogeneous direction and Chebyshev polynomials in the inhomogeneous direction is adopted to simulate the fluid particle dispersion. An inhomogeneity of Lagrangian statistics in turbulent boundary layer is investigated by releasing many particles at several different wall-normal locations and tracking those particles. The fluid particle dispersions and Lagrangian structure functions of velocity are scaled by the Kolmogorov similarity. The auto-correlations of velocity and acceleration are shown at the different releasing locations. Effect of initial particle location on the dispersion is analyzed by the probability density function at the several downstreams and time instants.

• 방송공학회논문지
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• 제16권3호
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• pp.501-509
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• 2011

In this paper, we propose an edge profile adaptive bi-directional diffusion interpolation method which consists of shock filter and level set. In recent years many interpolation methods have been proposed but all methods have some degrees of artifacts such as blurring and jaggies. To solve these problems, we adaptively apply shock filter and level set method where shock filter enhances edge along the normal direction and level set method removes jaggies artifact along the tangent direction. After the initial interpolation, weights of shock filter and level set are locally adjusted according to the edge profile. By adaptive coupling shock filter with level set method, the proposed method can remove jaggies artifact and enhance the edge. Experimental results show that the average PSNR and MSSIM of our method are increased, and contour smoothness and edge sharpness are also improved.

• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.567-579
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• 2009

Recently, Peng et al. proposed a primal-dual interior-point method with new search direction and self-regular proximity for LP. This new large-update method has the currently best theoretical performance with polynomial complexity of O($n^{\frac{q+1}{2q}}\;{\log}\;{\frac{n}{\varepsilon}}$). In this paper we use this search direction to propose a primal-dual interior-point method for convex quadratic programming (QP). We overcome the difficulty in analyzing the complexity of the primal-dual interior-point methods for convex quadratic programming, and obtain the same polynomial complexity of O($n^{\frac{q+1}{2q}}\;{\log}\;{\frac{n}{\varepsilon}}$) for convex quadratic programming.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.410-416
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• 2001

KLN thin films were fabricated on Pt coated Si(100) wafer using an rf-magnetron sputtering method. The grown KLN thin film consists of 4-fold grains. In this experiment, the structure of 4-fold grained thin film was investigated using XRD and SEM measurements. Pt layer was also deposited using the rf-magnetron sputtering method,. XRD measurement showed that he Pt thin film has Gaussian distribution form with strong (111) direction orientation. The KLN thin film has preferred-orientation of (001) direction, and the peak consists of 2 separate peaks; one with broad FWHM and the other with narrow FWHM. The sharp peak is due to single crystal, and combining with Em results, the 4-fold grain consists of singel crystals with c-axis normal to substrate.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.450-457
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• 1998

Abstract - Linear Synchronous Motor has a large airgap comparing with rotary-type motor and especially, Permanent Magnet Linear Synchronous Motor(PM-LSM) which uses permanent magnet as a magnetic field, has a very large effective magnet airgap owing to permanent magnet structure. Accordingly, in case of 2-D analysis of the motor, the analysis error becomes large because leakage flux by which normal direction of the analysis region can not be considered, In this paper, the characteristic of PM-LSM for Maglev vehicle is analyzed exactly by 3-D Finite Element Method(3-D FEM). As the result, the effect of lateral-direction airgap magnetic flux density distribution on the analysis precision has been investigated and the motor characteristics according to primary motor parameter have been also made clear quantitatively. The accuracy of 3-D FEM has been confirmed by comparing the calculated results with the experimental results.

• ETRI Journal
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• 제40권5호
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• pp.604-612
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• 2018

To solve the problem of unbalanced loads and the short network lifetime of heterogeneous wireless sensor networks, this paper proposes a node-selection algorithm based on energy balance and dynamic adjustment. The spacing and energy of the nodes are calculated according to the proximity to the network nodes and the characteristics of the link structure. The direction factor and the energy-adjustment factor are introduced to optimize the node-selection probability in order to realize the dynamic selection of network nodes. On this basis, the target path is selected by the relevance of the nodes, and nodes with insufficient energy values are excluded in real time by the establishment of the node-selection mechanism, which guarantees the normal operation of the network and a balanced energy consumption. Simulation results show that this algorithm can effectively extend the network lifetime, and it has better stability, higher accuracy, and an enhanced data-receiving rate in sufficient time.