• 한국컴퓨터정보학회논문지
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• 제8권4호
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• pp.63-68
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• 2003

지문 인식 시스템에서는 대부분 융선의 끝점과 분기점을 이용한다. 그러나 융선을 체인 코드화하여 이것을 이용한 훼손된 지문의 인식에 관해 연구하였다. 처리의 결과와 순서는 다음과 같이 요약 할 수 있다. (1)몇 개의 훼손된 지문획득, (2)전처리(잡음 제거를 위해 중간 값 필터링, 지역 또는 전역 히스토그램 균등화, 팽창과 침식, 세선화와 유사 이미지 제거), (3)최소 자승법 처리 후 융선 재구성, (4)체인 코드 벡터의 분포 계산, (5)전 처리된 지문 이미지에서 각 벡터의 값들은 거의 같은 결과 값을 보였다. 이 결과로부터 우리는 특징점을 이용한 시스템과 결합하여 사용한다면 더욱 성공적인 지문 인식 시스템이 될 것이라 추측한다.

• 한국조경학회지
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• 제27권4호
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• pp.59-64
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• 1999

This study is about gaining orientation through anchorage act of a group of ferryman. In addition, a point acquisition and character of landmark that is closely realated to a point acquisition would be clarified by studying the form of configuration of the earth and object which is used landmark for anchorage. There are 13 anchorage points in the north part of Pusan harbor. 12 anchorage points are used to anchor. A ferryman let a ship which is temporarily anchoring move safely and speedily at the anchorage point. At that time, he uses landmarks by a technique of Overlay View. Between landmarks and viewer would be formed exquisite location combination. A mountain peak, a peak of island, nature configuration of land such as intermitent rock and location, size and form of buildings or structures of a city were variously appeared as landscape elements which were used landmarks. Looking at conditions to be easily captured as a target object, 1. A particular point of a mountain ridge line which was not shield by buildings. 2. In case objects have similar form, the building which was located in the front or the highest. 3. In case of a singular object, whatever there is physical elements, that would be a target object. Through this study a configuration of the ground such as a mountain peak which is become the background of harbor landscape is very important element to find anchorage point in configuration of the ground and object. So, the continuous preservation of the contour line of mountain is needed to do safe and effective anchorage act.

• Ocean Systems Engineering
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• 제7권4호
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• pp.399-412
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• 2017

The Gauss-Legendre integral method is applied to numerically evaluate the Green function and its derivatives in finite water depth. In this method, the singular point of the function in the traditional integral equation can be avoided. Moreover, based on the improved Gauss-Laguerre integral method proposed in the previous research, a new methodology is developed through the Gauss-Legendre integral. Using this new methodology, the Green function with the field and source points near the water surface can be obtained, which is less mentioned in the previous research. The accuracy and efficiency of this new method is investigated. The numerical results using a Gauss-Legendre integral method show good agreements with other numerical results of direct calculations and series form in the far field. Furthermore, the cases with the field and source points near the water surface are also considered. Considering the computational efficiency, the method using the Gauss-Legendre integral proposed in this paper could obtain the accurate numerical results of the Green function and its derivatives in finite water depth and can be adopted in the near field.

• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.187-193
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• 1998

This paper proposes an advanced visual tracking algorithm for the stable grasping of a moving target(2D). This algorithm is programmed to find grasping points of an unknown polygonal object and execute visual tracking. The Kalman Filter(KF) algorithm based on the SVD(Singular Value Decomposition) is applied to the visual tracking system for the tracking of a moving object. The KF based on the SVD improves the accuracy of the tracking and the robustness in the estimation of state variables and noise statistics. In addition, it does not have the numerical unstability problem that can occur in the visual tracking system based on Kalman filter. In the grasping system, a parameterized family is constructcd, and through the family, the grasping system finds the stable grasping points of an unknown object through the geometric properties of the parameterized family. In the previous studies, many researchers have been studied on only 'How to track a moving target'. This paper concern not only on 'how to track' but also 'how to grasp' and apply the grasping theory to a visual tracking system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1598-1602
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• 2003

The parallel-type mechanism provides more accurate and stiff motion than the serial-type mechanism. However, in case of using the haptic device, the performance of the force reflection can be deteriorated due to the singular points existing in workspace. In this paper, we propose a redundantly actuated parallel 3-DOF haptic device, which is singularity-free in the workspace and has an improved force reflection capability. In addition, we propose a new force distribution algorithm, which can reflect force of both high and low resolution, using two sets of actuator with different size. Redundant actuators are attached to the base frame in order to minimize the inertia of the system. Moreover, a wire and gear reduction system is employed to achieve high force reflection along with soft feeling. We confirm the performance of the force reflection capability throughout simulation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.170-175
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• 2009

Shock focusing is related with explosive release of shock wave energy on a narrow spot in a short duration of time triggering a spontaneous high pressure near the focal point. It is well known that reflection of planar incident shock wave from the metallic concave mirror such as ellipsoidal, paraboloidal or hemispherical cavities will focus on a focal point. We intend to improve the computational results using a wave propagation algorithm and to resolve the mushroom-like structure. For computation of the concave cavity flow, it is not easy to use a single-block mesh because of the many singular points in geometry and coordinates. We have employed a uniform Cartesian-grid method for the wave propagation algorithm.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.319-322
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• 2000

본 논문에서는 지문영상으로부터 제안한 알고리즘을 이용하여 특이점(Core, Delta)을 추출한 후 특이점의 개수와 종류에 따라서 5가지 부류(arch, tented arch, left loop, right loop, whorl)로 지문영상을 분류하였다. 지문영상을 8*8블록과 16*16블록으로 분할한 후 3*3 Sobel 마스크를 씌워서 대표 방향을 구하였다. 또한 블록으로 분할한 영상으로부터 분산을 구하여 전경과 배경을 분리(segmentation)시켜 수행속도를 향상시켰다. 전처리 과정으로는 일정한 블록마다 임계값을 다르게 적용시키는 블록 이진화 기법을 사용하였으며 특이점을 추출하기 위해서 서로 크기가 다른 2개의 블록으로 영상을 분할하였다. 우선 8*8블록으로 영역을 분할한 후 방향 성분을 구하고 특이점들을 추출하였다. 이 경우 잡영 때문에 특이점이 너무 많이 추출되는 문제점이 있으므로 이러한 해결책으로 16*16블록으로 영역을 분할하여 방향 성분을 구하고 특이점을 추출하였다. 이렇게 다른 두 영역에서 동시에 나타나는 특이점을 후보 특이점으로 잡아서 그 후보 특이점 주변으로 Poincare 지수를 적용하여 확실한 특이점을 선택한 후 5가지의 지문 형태로 분류하였다. 실험결과 대부분의 지문영상에 대하여 강건한 분류 특성을 보이고 있음을 확인하였다.

• ETRI Journal
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• 제40권4호
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• pp.531-536
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• 2018

The weighted K-nearest neighbor (WKNN) algorithm is used to reduce positioning accuracy, as it uses a fixed number of neighbors to estimate the position. In this paper, we propose a dynamic threshold location algorithm (DH-KNN) to improve positioning accuracy. The proposed algorithm is designed based on a dynamic threshold to determine the number of neighbors and filter out singular reference points (RPs). We compare its performance with the WKNN and Enhanced K-Nearest Neighbor (EKNN) algorithms in test spaces of networks with dimensions of $20m{\times}20m$, $30m{\times}30m$, $40m{\times}40m$ and $50m{\times}50m$. Simulation results show that the maximum position accuracy of DH-KNN improves by 31.1%, and its maximum position error decreases by 23.5%. The results demonstrate that our proposed method achieves better performance than other well-known algorithms.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1193-1204
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• 2011

In the present paper we consider a differential-algebraic prey-predator model with stage structure for prey and harvesting of predator species. Stability and instability of the equilibrium points are discussed and it is observed that the model exhibits a singular induced bifurcation when the economic profit is zero. It indicates that the zero economic profit brings impulse, i.e. rapid expansion of the population and the system collapses. For the purpose of stabilizing the system around the positive equilibrium, a state feedback controller is designed. Finally, numerical simulations are given to show the consistency with theoretical analysis.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.219-226
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• 1996

A two-step approach has been used to obtain a new transition criterion for the stratified and nonstratified flow in horizontal pipe: (1) In the first step, a more general expression than the existing models for the flow transition criterion has been derived from the analysis of singular points and neutral stability conditions, or the parallel lines conditions of the transient one-dimensional two- phase flow equations of two-fluid model. (2) In the second step, introducing simplifications and incorporating a parameter into the general expression obtained in the first step to satisfy a number of physical conditions a priori specified, a new simple flow transition criterion for horizontal pipes has been derived. Comparison between results predicted by the present theory with the experimental data and theories in the pipe flow conditions, show good agreement.