• 반도체디스플레이기술학회지
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• 제11권2호
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• pp.27-31
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• 2012

This paper proposes a new method of character segmentation in a grayscale image using the standard deviation. Firstly, the proposed method scans vertically the region of interest in an image in order to calculate a standard deviation for each scan line. Characters' standard deviations are much bigger than the background's. Therefore, it is possible to segment characters vertically using the differentiation of those two types of standard deviations. Secondly, the method scans each vertically segmented image horizontally at this time, and then segments each image similarly. The proposed method is implemented using C language in an embedded Linux system for a high-speed real-time image processing. Experiments were conducted by using credit card images. The results show that the proposed algorithm is quite successful for most credit cards. However, the method fails in some credit cards with strong background patterns.

• 대한교통학회지
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• 제29권4호
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• pp.103-111
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• 2011

속도는 교통안전에 있어서 중요한 요소이며 교통사고와 밀접한 연관성이 있다. 국외의 속도변화와 사고위험 간 관계 관련 연구에서는 평균속도와 속도 표준편차가 증가하면 사고율도 증가한다고 제시하고 있지만, 국내 연구에서는 속도와 사고위험간의 관계 수립이 미흡한 실정이다. 따라서 본 연구에서는 루프검지기 속도자료와 고속도로 사고자료를 이용하여 속도를 이용한 고속도로 구간 사고율 예측모형을 개발하였다. 경부고속도로 2005~2009년의 5년 간 천안~양재 양방향 총 22구간에서 발생한 486건의 사고자료와 구간별 루프검지기 자료를 기초로 분석을 수행하였다. 종속변수를 사고율로 설정하고, 중앙 집중화경향을 나타내는 값과, 변동성을 나타내는 값, 연평균 일 교통량, 구간길이 등을 통해 산출한 구간정보 변수를 독립변수 후보로 설정하였다. 통계적 분석을 통해 사고율에 직접적으로 영향을 미치는 변수를 설정한 결과 중앙값, 최소값, 표준편차를 독립변수로 설정하였다. 모형수립 결과 실제 사고율과 예측 사고율간의 높은 상관도를 보였다. 본 연구에서 개발한 모형은 속도변화에 의한 교통안전 위험도 분석에 효과적으로 사용되어 다양한 교통정책 및 운영관리전략 시행에 따른 교통안전 효과분석시 유용한 도구로서 활용될 수 있을 것으로 기대된다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권8호
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• pp.426-430
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• 1999

In this paper, a speed sensorless algorithm for a high-speed induction motor is proposed. The proposed algorithm simply estimates rotor speed by integrating the deviation between the command current value of a controller and the real current value of the motor. To estimate rotor speed without a speed sensor, a fuzzy speed controller and a neural network speed estimator are applied. Computer simulation and implementation of the proposed system is described.

• Wind and Structures
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• 제11권5호
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• pp.361-376
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• 2008

This paper considers internal pressure fluctuations for a range of building volumes and dominant wall opening areas. The study recognizes that the air flow in and out of the dominant opening in the envelope generates Helmholtz resonance, which can amplify the internal pressure fluctuations compared to the external pressure, at the opening. Numerical methods were used to estimate fluctuating standard deviation and peak (i.e. design) internal pressures from full-scale measured external pressures. The ratios of standard deviation and peak internal pressures to the external pressures at a dominant windward wall opening of area, AW are presented in terms of the non-dimensional opening size to volume parameter, $S^*=(a_s/\bar{U}_h)^2(A_W^{3/2}/V_{Ie})$ where $a_s$ is the speed of sound, $\bar{U}_h$ is the mean wind speed at the top of the building and $V_{Ie}$ is the effective internal volume. The standard deviation of internal pressure exceeds the external pressures at the opening, for $S^*$ greater than about 0.75, showing increasing amplification with increasing $S^*$. The peak internal pressure can be expected to exceed the peak external pressure at the opening by 10% to 50%, for $S^*$ greater than about 5. A dominant leeward wall opening also produces similar fluctuating internal pressure characteristics.

• 한국정밀공학회지
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• 제13권5호
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• pp.67-73
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• 1996

The necessity for more accurate automatic flatness control(AFC) system has increased of customers' requirement for cold rolled steel sheet. Therefore, many cold rolling mills replaced its AFC system with a measuring roll of the contact type form the non-contact type. In this paper. The performance of AFC system of contact type has been investigated under industrial conditions. It has two kinds of actuator: roll bender, spot cooling system. The test results are as follows: The more strip thickness is thick, the smaller the I value, and the more it is thin, the bigger the I value. And a complex distribution of strip tension was controlled, for example, not only a pocket wave but also a simple center wave and edge wave. Because the tension deviation is larger at acceler- ation speed and decelerationspeed than steady speed, AFC system of contact type is better to adopt over 50m/mim. AFC system reduces rapidly large flatness deviation. The maximum I value of strip has been decreased to 13 I, and sticker, defects caused by poor flatness, have been decreased about 60%.

• 한국ITS학회 논문지
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• 제20권5호
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• pp.75-82
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• 2021

국내 2020년 기준 교통사고 건수는 약 23만 건으로, 고속도로는 비반복적 정체와 높은 주행 속도로 인해 다른 도로 대비 교통사고 발생 건수당 사망자수가 2배 이상으로 나타나고 있다. 고속도로의 교통정보는 도로의 중심선을 이용한 노드, 링크를 기준으로 제공하고 있으나 세분화된 속도정보를 주지 못하고 있다. 최근 자율주행차 뿐만 아니라 일반 차량에서도 장애물 모니터링, 위치 측정을 위한 차량용 센서 장착이 일반화되고 있어, 대용량 위치 기반 데이터를 이용한 분석은 처리속도에 따라 실시간 서비스가 가능하다. 본 연구는 대용량 위치기반 개별 차량 정보의 분석을 위한 공간 기반의 맵핑 방법을 제시하였다. 경위도 각각 2개로 분할하는 4진법 기준의 분할 방법을 적용하여 개별 차량의 공간 코드를 생성하여 지오코딩 하는 방법으로 처리 속도를 대폭 증가 시켰다. 공간이 세분됨에 따라 평균속도는 유사하였으나 속도의 표준편차는 점차 감소하였으며 9회 분할 이후는 그 감소 폭이 작아 졌다.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.167-173
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• 2011

This paper presents a method for the development of the impedance locus to test the dynamic characteristics of protective relays. Specifically, using the proposed method, the impedance locus can comprise three impedance points, and the speed of impedance trajectory can be adjusted by frequency deviation. This paper is divided into two main sections. The first section deals with the configuration of impedance locus with voltage magnitude, total impedance magnitude, and impedance angle. The second section discusses the control of the locus speed with the means of the deviation between two frequencies. The proposed method is applied to two machine equivalent systems with offline simulation (i.e., PSCAD) and real-time simulation (i.e., real-time simulation environment) to demonstrate its effectiveness.

• Journal of electromagnetic engineering and science
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• 제13권3호
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• pp.151-157
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• 2013

Marine radars are affected by sea and rain clutters, which can make target discrimination difficult. The clutter standard deviation and improvement factor are applied using multiple parameters-moving speed of radar, antenna speed, angle, etc. When a radar signal is processed, a Data Matrix Bank (DMB) filter can be applied to remove sea clutters. This filter allows detection of a target, and since it is not affected by changes in adjacent clutters resulting from a multi- target signal, sea state clutters can be removed. In this paper, we study the level for clutter removal and the method for target detection. In addition, we design a signal processing algorithm for marine radars, analyze the performance of the DMB filter algorithm, and provide a DMB filter algorithm design. We also perform a DMB filter algorithm analysis and simulation, and then apply this to the DMB filter and cell-average constant false alarm rate design to show comparative results.

• 풍력에너지저널
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• 제5권1호
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• pp.50-55
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• 2014

Surface Permanent-Magnetic-Synchronous-Generator (SPMSG) discussed in the present study has operational characteristics such as high rotational speed over 1,000 rpm and centrifugal force of 12 kN·m for each magnet. Structure-development analysis for the minimization of rotor-core weights and the maximization of thermal emission is performed by applying the aluminum-laminated cap which combines the advantages of IPM and SPM in order to overcome the difficulty that attaching the magnet to rotor-core only with an adhesive. In this study, the simulations in terms of structure and electromagnetic were performed with the variable parameters such as shape and thickness of laminated-cap and division method of magnet. As a result, condition for minimized centrifugal force with minimum loss is derived.

• 한국산학기술학회논문지
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• 제6권6호
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• pp.502-505
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• 2005

e-러닝에서 멀티미디어콘텐트의 사용이 증가함에 따라 e-러닝 시스템에서 제공하는 콘텐트의 크기 편차가 증가하고 있으며, 이는 e-러닝 사용자에 대한 응답시간의 편차를 크게 하여 학습의 효율성을 떨어뜨리는 요인이 되고 있다. 따라서 멀티미디어콘텐트를 활용한 e-러닝 시스템에서 사용자의 응답시간 편차 개선에 대한 연구가 필요하다. 본 연구의 목적은 e-러닝 사용자의 응답시간의 편차를 줄이는 것이며 이를 위해 다중 계층 구조의 혼합형 e-러닝 시스템을 설계하였다. 또한 실험을 통해 편차 개선을 확인하였다.