• 한국시뮬레이션학회논문지
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• 제14권3호
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• pp.147-154
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• 2005

In conventional approaches such as a functinal approach or a parametric approach to online signature verification, which could not deal with the local shape of signature, much various important informations inherent in the local part of signature shape have been overlooked. In this paper, we try a structural approach in which a signature is represented as a structural form of handwriting primitives and the local parts along a signature handwriting can be selectively compared according to their discrimination power in the process of signature verification, As a result, the error rate is diminished in the case that the weights of subpattern units is applied into comparing process, which is the degree of discrimination power of local part. And also, the global variation and complexity of each signature extracted from the analysis of local shape is found useful in determining the decision threshold more precisely.

• 지적과 국토정보
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• 제52권1호
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• pp.5-16
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• 2022

다각형 필지의 면적오차계산에 대한 일반식으로부터 직사각형 필지의 면적오차계산식을 도출하고 관련 법률 시행령에서 정하고 있는 면적오차계산의 상수항 0.026² × M(축척분모)이 갖는 의미를 분석하였다. 그 결과, 현행의 면적오차 공식은 직사각형 필지모형으로서 도해측량의 특성을 적절히 반영하고 있으나, 정량적으로는 면적오차를 비교적 크게 허용한다는 것을 알 수 있었다. 또, 면적이 같더라도 필지의 형상에 따라 정사각형 필지보다 50% 더 많은 면적오차가 산출될 수 있다는 문제, 필지 분할시 허용면적오차가 달라져야 하는 문제 등을 파악하였다. 이와 더불어, 본 연구에서 도출한 면적오차계산식으로써 지적측량의 관점에서 문제를 한꺼번에 해결할 수 있는 방안을 제시하였다. 즉, 필지의 크기와 형상을 반영하는 문제, 측량의 정확도를 반영하는 문제, 도해측량과 수치측량을 구분할 필요 없이 단일의 면적오차계산식을 채택하는 문제에 대한 해결책이다. 이들 문제를 해소하는 새로운 면적오차계산식의 채용은 많은 관련 요소들의 개선을 촉진하여 선진적 지적제도로의 발전을 강화할 것이다.

• 한국생산제조학회지
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• 제8권4호
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• pp.19-28
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• 1999

In order to control thermal deformation of the machine origin of machine tools a empirical model and a compensation system have been developed, Prior to empirical modeling the volumetric error considering shape errors and joint errors of slides is formulated through the homogeneous transformation matrix (HTM) and kinematic chain. Simulation results of the HTM method show that the thermal error of the machine origin is more critical than position-dependent errors. In order to make a stable and effective software error compensation system the GMDH (Group Method of Data Handling) models are constructed to estimate the thermal deformation of the machine origin by measuring deformation data and temperature data. A test bar and gap sensors are used to measure the deformation data. In order to compensate the estimated error the work origin shift method is developed by implementing a digital I/O interface board between a CNC controller and an IBM PC. The method shifts the work origin as much as the amounts which are calculated by the pre-established thermal error model. The experiment results for a vertical machining center show that the thermal deformation of the machine origin is reduced within $\pm$5$mu extrm{m}$.

• 한국정밀공학회지
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• 제33권7호
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• pp.595-600
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• 2016

An orbital grinding system uses a special motion to machine crankshafts in ships. When a crankshaft is operated, eccentric pins rotate and a grinding wheel moves in order to grind the pins. Thermal error caused by heat generated in the grinding process decreases the quality of the final product. In this study, the thermal error of an orbital grinding system caused by heat generation was investigated in order to predict the extent of thermal error that can occur during the grinding process. Since the machine position changes during orbital grinding, the pin part is divided into 30 degree intervals and heat is generated. Total thermal error was measured by summing the thermal errors associated with the pin and the grinding wheel. Total thermal error was found to reach a maximum at 60 degrees and a minimum at 210 degrees because of the shape of the crankshaft.

• 한국멀티미디어학회논문지
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• 제13권11호
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• pp.1586-1593
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• 2010

확률적 패턴 매칭과 동적 패턴 매칭의 어휘 인식 오류 보정 방법에서는 핵심어를 기반으로 문장을 의미론적으로 분석하므로 형태론적 변형에 따른 핵심어 분석이 어려운 문제점을 가지고 있다. 이를 해결하기 위해 본 연구에서는 음절 복원 알고리즘에서 형태소 분석을 이용하여 인식된 음소 열을 의미 분석 과정을 통해 음소의 의미를 파악하고 형태론적 분석으로 문장을 복원하여 어휘 오인식률을 감소하였다. 시스템 분석을 위해 음소 유사률과 신뢰도를 이용하여 오류 보정률을 구하였으며, 어휘 인식 과정에서 오류로 판명된 어휘에 대하여 오류 보정을 수행하였다. 에러 패턴 학습을 이용한 방법과 오류 패턴 매칭 기반 방법, 어휘 의미 패턴 기반 방법의 성능 평가 결과 2.0%의 인식 향상률을 보였다.

• 전산구조공학
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• 제11권1호
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• pp.261-274
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• 1998

본 연구에서는 무요소방법에 적응적 해석기법을 적용하기 위한 부분 및 전체오차의 평가기법을 제안하였다. 본 연구에서 제안한 오차의 평가방법은 무요소방법에서 계산된 응력이 오차가 큰 영역에서 진동한다는 특성을 이용한 것으로 해석결과 얻어진 응력을 낮은 차수의 형상함수로 투사하는 후처리를 함으로써 가상진동모우드를 제거하고 이때 얻어진 투영응력과 원래의 응력을 비교하여 부분오차 및 전체오차를 구할 수 있다. 1차원 및 2차원 예제해석을 통하여 투영응력을 구할 때 가능한 한 작은 영향영역을 사용하는 것이 바람직하다는 것을 보였으며 이는 영향영역의 크기를 과도하게 설정할 경우 투영응력을 과대 평가할 수 있기 때문이다. 본 연구에서 제안한 오차의 평가기법은 다른 무요소 방법에 적용될 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.481-486
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• 2007

The Zienkiewicz-Zhu(Z/Z) error estimate is slightly modified for the hierarchical p-refinement, and is then applied to L-shaped plates subjected to bending to demonstrate its effectiveness. An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the superconvergent patch recovery(SPR) technique. The modified Z/Z error estimate p-refinement is different from the conventional approach because the high order shape functions based on integrals of Legendre polynomials are used to interpolate displacements within an element, on the other hand, the same order of basis function based on Pascal's triangle tree is also used to interpolate recovered stresses. The least-square method is used to fit a polynomial to the stresses computed at the sampling points. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly or selectively. It is noted that the error decreases rapidly with an increase in the number of degrees of freedom and the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• International journal of advanced smart convergence
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• 제8권4호
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• pp.104-112
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• 2019

This study proposed a robust detection algorithm. It detects face more stably with respect to changes in light and rotation forthe identification of a face shape. The proposed algorithm uses face shape asinput information in a single camera environment and divides only face area through preprocessing process. However, it is not easy to accurately recognize the face area that is sensitive to lighting changes and has a large degree of freedom, and the error range is large. In this paper, we separated the background and face area using the brightness difference of the two images to increase the recognition rate. The brightness difference between the two images means the difference between the images taken under the bright light and the images taken under the dark light. After separating only the face region, the face shape is recognized by using the self-organization feature map (SOFM) algorithm. SOFM first selects the first top neuron through the learning process. Second, the highest neuron is renewed by competing again between the highest neuron and neighboring neurons through the competition process. Third, the final top neuron is selected by repeating the learning process and the competition process. In addition, the competition will go through a three-step learning process to ensure that the top neurons are updated well among neurons. By using these SOFM neural network algorithms, we intend to implement a stable and robust real-time face shape recognition system in face shape recognition.

• 소성∙가공
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• 제25권2호
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• pp.109-115
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• 2016

In the current study, automatic tool compensation is accomplished by using a finite element stamping analysis for a center roof rail made of UHSS in order to satisfy the specifications for shape accuracy. The initial blank shape is calculated from a finite element inverse analysis and potential forming defects such as tearing and wrinkling are determined by the finite element stamping analysis based on the initial tool shape. The blank shape is optimized to meet the shape requirements of the final product with the stamping analysis, and die compensation is determined with the information about springback. The specifications for shape accuracy were successfully achieved by the proposed die compensation scheme using the finite element stamping analysis. The current study demonstrates that the compensation tendency is similar when the proposed scheme is used or when the compensation is performed by trial and error in the press-shop. This similarity verifies that the automatic compensation scheme can be used effectively in the first stage of tool design especially for components made from UHSS.

• 한국생산제조학회지
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• 제23권5호
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• pp.512-518
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• 2014

In this paper, the influence of part shape complexity and die type on forming accuracy in incremental sheet metal forming is presented. The part shape complexities are classified into two types, namely, of one and two-step shapes. Correspondingly, die types are classified into three types, namely, of no-, partial, and full die types. The experimental tests are performed separately on negative and positive forming methods. It is shown that for the one-step shape, there are no significant differences in forming errors between the cases of no- and full die types when the negative forming method is used. Furthermore, the full die type is better than the partial die when positive forming is used. For the two-step shape case, the full die type always exhibits better forming accuracy than the no- and partial die types, irrespective of the forming method used.