• 대한기계학회논문집A
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• 제24권4호
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• pp.1024-1031
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• 2000

The plate waves propagating in thin plates have dispersive nature showing the dependence of velocities on the frequency. Wavelet transform (WT) using Gabor function can be used to analyze the dispersive waves in the time-frequency domain, and then to find the arrival time of the waves propagating in the plate. Plate waves in the aluminum plate of 3 mm thickness were identified and generated by pencil lead breaks and the lowest order symmetric ($S_o$) and antisymmetric ($A_o$) modes were analyzed by the WT method. The measured group velocities agreed very well with theoretical predictions in the frequency range of 50-400 kHz. The pencil breaks were also used to simulate acoustic emission sources in the plate, and the source location algorithm using the wavelet transform of dispersive plate waves was found to give accurate results.

• 한국컴퓨터정보학회논문지
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• 제12권6호
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• pp.261-268
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• 2007

본 논문에서는 문자가 가지고 있는 특성을 이용하여 에지 투영을 기반으로 자동차 번호판 영역을 추출하는 기법을 제안하였다. 차량의 번호판 영역을 추출하기 위하여, 바탕과 문자부분의 명암비가 매우 크다는 점을 이용한다. 또한, 에지영상을 바탕으로 투영기법을 적용하여 문자 영역을 추출한다. 특히, 새로운 번호판 규격은 가로방향으로 많은 수의 숫자를 가지기 때문에 가로 방향으로 투영된 데이터는 일정한 폭의 누적 값을 가지며, 이러한 점을 이용하여 번호판 영역을 추출한다. 또한 세로방향의 경우 형태 정합에 의해 번호판을 추출하는 방법을 제안한다. 제안된 기법은 특히, 새로운 번호판 규격에 더욱 효과적이다. 본 알고리즘에 대한 모의실험 결과에서, 여러 가지 번호판에 대해 90% 성공률을 나타냄을 보여준다.

• Smart Structures and Systems
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• 제22권3호
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• pp.249-257
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• 2018

This study contributes to evaluate multiphase topology optimization design of plate-like elastic structures with constant thickness and Reissner-Mindlin plate theory. Stiffness and adjoint sensitivity formulations linked to Reissner-Mindlin plate potential energy of bending and shear are derived in terms of multiphase design variables. Multiphase optimization problem is solved through alternative active-phase algorithm with Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples verify efficiency and diversity of the present topology optimization method of Reissner-Mindlin elastic plates depending on multiphase and Poisson's ratio.

• Smart Structures and Systems
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• 제17권5호
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• pp.725-742
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• 2016

This paper is focused on stiffness ratio effect and a new method to specify the best pattern of piezoelectric patches placement around a hole in a plate under tension to reduce the stress concentration factor. To investigate the stiffness ratio effect, some different values greater and less than unity are considered. Then a python code is developed by using particle swarm optimization algorithm to specify the best locations of piezoelectric actuators around the hole for each stiffness ratio. The results show that, there is a line called "reference line" for each plate with a hole under tension, which can guide the location of actuator patches in plate to have the maximum stress concentration reduction. The reference line also specifies that actuators should be located horizontally or vertically. This reference line is located at an angle of about 65 degrees from the stress line in plate. Finally two experimental tests for two different locations of the patches with various voltages are carried out for validation of the results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.438-446
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• 1999

Crop minimization of the top and bottom ends of hot rolled plate, in a plate, in a plate mill, has been investigated. The existing model to determine the edging pattern at the finishing rolling pass was not reasonable to get high width accuracy and rolling yields. New models including width prediction have been formulated by using neural network model of back propagation learning algorithm and statistical analysis based on the actual production rolling data to give the optimal pattern for minimizing trimming loss. Using these models, at a given rolling condition of broadside pass and finishing pass and the permissible condition of width variation, it was possible to minimize crip at the top and bottom ends according to optimum procedure in plate mill. An application to improve the plan view pattern reduced width variation by 23% and crop length by 30% on average with an effective fishtail crop shape.

• Steel and Composite Structures
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• 제27권2호
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• pp.177-184
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• 2018

This study contributes to evaluate multiphase topology optimization design of plate-like structures on elastic foundations by using classic plate theory. Multi-material optimal topology and shape are produced as an alternative to provide reasonable material assignments based on stress distributions. Multi-material topology optimization problem is solved through an alternative active-phase algorithm with Gauss-Seidel version as an optimization model of optimality criteria. Stiffness and adjoint sensitivity formulations linked to thin plate potential strain energy are derived in terms of multiphase design variables and Winkler-Pasternak parameters considering elastic foundation to apply to the current topology optimization. Numerical examples verify efficiency and diversity of the present topology optimization method of elastic thin plates depending on multiple materials and Winkler-Pasternak parameters with the same amount of volume fraction and total structural volume.

• 한국멀티미디어학회논문지
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• 제7권1호
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• pp.35-43
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• 2004

본 논문에서는 고속도로나 도심 진입 차량의 무인 자동과금 및 주요시설 출입 차량의 통제와 관리를 위하여 차량번호판 인식뿐만 아니라 차량 표시 문자와 제조사 식별자 검출 분류하여 차량의 정보를 판독하는 차량정보인식 및 자동과금시스템을 제안하였다. 제안한 알고리즘은 차량 후면부에서 획득된 영상으로부터 잡음제거, 세선화 등의 전처리 과정을 수행하고 템플릿 마스킹 및 레이블링 연산처리를 수행하여 차량표시문자, 제조사 표식자 및 번호판 영역을 각각 검출하였다. 또한, 검출된 특징 영역으로부터 특징자의 구조적 특징 및 패턴정보를 이용하여 표시문자와 제조사 표식자를 분류하였고, 하이브리드 패턴벡터와 세븐세그먼트 패턴벡터를 사용하여 차량번호판의 문자 및 숫자를 각각 인식하였다. 실험에서는 실제 고속도로상에서 제안한 차량인식 시스템에서 획득된 실 영상을 사용하여 인식 성능을 수행하였다. 실험 결과 제안한 알고리즘이 잡음, 외부환경, 차량의 크기에 무관하게 차량 특징자를 정확히 검출 분류하였으며 제안한 시스템은 범죄차량 단속, 차량자동과금 및 관공서 등의 차량입출력 관리의 무인화에 적용이 가능하다.

• 전기학회논문지
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• 제66권9호
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• pp.1334-1340
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• 2017

In this paper, a tie-plate shape is optimized by using the numerical technique to reduce the stray load loss of the tie-plate which is a mechanical structure for assembling and supporting of the transformer core. The eddy current loss of the structure is calculated by an electromagnetic field FEM program and the results are compared with 4 different shapes of tie-plates. Since the thickness of the tie-plate is very thin, and the skin depth is very small, the number of FE elements for 3-D transformer model is too big to solve. So, the surface impedance boundary condition (SIBC) is used to reduce the system matrix size and its computing time. To verify the method a 2.5 MVA 22,900/380V distribution transformer is simulated using one objective function and three design variables with some constraints. The final optimized tie-plate has three slots of 6 mm width and 23 mm gap, and the loss is reduced by 75 %. Consequently, the proposed algorithm seems to be considerably applicable to electric machinery as well as power transformer.

• 제어로봇시스템학회논문지
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• 제20권7호
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• pp.718-723
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• 2014

In this paper, we developed the inspection system of electric vehicle battery plate using image processing. Four cameras are used for acquiring the principal parts of the plate, and several steps of image processing for extracting significant dimensions of the plate such as widths and lengths. As a preceding step, calibration of four cameras is carried for compensating distorted images using dot-arrayed sheet. Coordinate systems for four cameras are defined where one coordinate system is assigned to the reference coordinate system to which the others are relatively described. Line information of the edge in the windowed image is extracted using elaborate edge-detection algorithm, and finally the intersection points between lines are extracted to calculate widths and lengths of the plate from which the error status of the battery plate is decided.

• 한국정보통신학회논문지
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• 제12권7호
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• pp.1278-1290
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• 2008

본 논문은 자동차 번호판 인식 시스템의 전반적인 성능을 향상시키기 위한 전처리 방법과 신경회로망을 이용한 문자 인식기를 제안한다. 먼저 자동차 번호판 영상에서 번호판의 외곽 직선을 가상 직선 매칭에 의해 검출하고 검출된 직선의 교점을 구하여 4개의 외곽 꼭지점을 구한다. 4개의 꼭지점 좌표에 의해 양선형 변환으로 직사각형 모양의 번호판 영상으로 정규화한다. 정규화된 번호판 영상으로부터 문자를 추출한 뒤 Delta-bar-delta 알고리즘에 의해 학습된 신경 회로망 기반 인식기로 번호판을 인식한다. 다양한 환경에서 획득된 자동차 번호판 영상을 대상으로 실험한 결과 제안된 번호판 이미지의 정규화에 의해 인식 성능이 16%까지 향상됨을 확인하였다.