• 제목/요약/키워드: Line distortion

검색결과 499건 처리시간 0.022초

Scheme to Improve the Line Current Distortion of PFC Using a Predictive Control Algorithm

  • Kim, Dae Joong;Park, Jin-Hyuk;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • 제15권5호
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    • pp.1168-1177
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    • 2015
  • This paper presents a scheme to improve the line current distortion of power factor corrector (PFC) topology at the zero crossing point using a predictive control algorithm in both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The line current in single-phase PFC topology is distorted at the zero crossing point of the input AC voltage because of the characteristic of the general proportional integral (PI) current controller. This distortion degrades the line current quality, such as the total harmonic distortion (THD) and the power factor (PF). Given the optimal duty cycle calculated by estimating the next state current in both the CCM and DCM, the proposed predictive control algorithm has a fast dynamic response and accuracy unlike the conventional PI current control method. These advantages of the proposed algorithm lower the line current distortion of PFC topology. The proposed method is verified through PSIM simulations and experimental results with 1.5 kW bridgeless PFC (BLPFC) topology.

열간가공의 변형에 미치는 곡률의 영향에 관한 연구 (Effect of Curvature on Deformation caused by Thermal Plate Forming)

  • 이주성
    • 한국해양공학회지
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    • 제25권2호
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    • pp.67-72
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    • 2011
  • This study had the goal of investigating the effect of the curvature along the heating line on the transverse angular distortion of plates having an initial curvature from line heating. A thermo-elasto-plastic analysis was carried out using 54 models with various radii of curvature, plate thicknesses, and heating speeds. The results show the effect of the curvature along the heating line on the angular distortion in relation to changes in the magnitudes of the curvature, heating speed, and plate thickness. The present numerical results show that the time history of the angular distortion after cooling and reaching the final deformed shape for a plate having an initial curvature is quite different from that of a flat plate. This emphasized the importance of considering the curvature effect on the transverse angular distortion. From the viewpoint of the curvature effect on the deformation, it has been seen that the curvature does not affect the transverse shrinkage. In this study the predicting formula for the transverse angular distortion was derived through a regression analysis. It showed that as the curvature increased, the angular distortion was reduced because of the higher bending rigidity at the same heat input parameter, and the peak points moved toward the origin as the curvature increased.

Plumb Line Method에 의한 렌즈왜곡보정에 관한 연구 (A Study on the Correction of tens Distortion by Plumb tine Method)

  • 강준묵;오원진;윤희천
    • 한국측량학회지
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    • 제7권2호
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    • pp.45-51
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    • 1989
  • 랜즈왜곡은 상의 위치를 변화시키므로 이에 대한 보정은 사진측량의 정확도 향상에 중요한 의미를 지니고 있다. 본 연구는 기준점 성과와 space resection의 과정없이 단사진으로 보정계수 결정이 가능한 plumb line method를 이용하여 거리에 따른 측정용, 비측정용 카메라의 렌즈왜곡 보정계수를 구하고 이를 실제 피사체의 3차원 위치해석에 적용, 정확도 향상을 기하고자 함에 목적이 있다. 그 결과, 측정용 카메라는 큰 차이를 보이지 않으나 비측정용 카메라는 방사방향, 접선방향 왜곡 보정계수가 촬영거리에 따라 면하므로 촬영거리에 따른 보정계수 적용이 바람직하며, 비측정용 카메라에 이를 적용하였을 경우 오차가 약 30%∼76%까지 현저히 감소되었다.

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고주파 유도가열을 이용한 선상가열 시 각 변형 예측에 관한 연구 (A study on the prediction of the angular distortion in line heating with high frequency induction heating)

  • 박동환;진형국;박성식;신상범
    • Journal of Welding and Joining
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    • 제33권1호
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    • pp.80-86
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    • 2015
  • The purpose of this study is to establish the predictive method of the angular distortion caused by the line heating process with high frequency induction heating. In order to do it, the heat input model for the high frequency induction heating system was established through comparing the temperature evaluation results obtained by both FEA and experiment. The critical heating conditions to prevent the degradation of the work piece with various thicknesses were identified by FEA and microstructure test results. Under the critical heating conditions, the extensive line heating tests were performed. According to the test results, it was found that the angular distortion behavior of the heated plates could be defined as the function of heat intensity and the rigidity of heated plate. In addition, it was clarified that the angular distortion strongly depended on the size of test specimen such as the length and the width of the heated plate. Based on these results, the predictive equation for the angular distortion was established with the function of heat intensity, bending rigidity and size of heated plate.

Correction of Signboard Distortion by Vertical Stroke Estimation

  • Lim, Jun Sik;Na, In Seop;Kim, Soo Hyung
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제7권9호
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    • pp.2312-2325
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    • 2013
  • In this paper, we propose a preprocessing method that it is to correct the distortion of text area in Korean signboard images as a preprocessing step to improve character recognition. Distorted perspective in recognizing of Korean signboard text may cause of the low recognition rate. The proposed method consists of four main steps and eight sub-steps: main step consists of potential vertical components detection, vertical components detection, text-boundary estimation and distortion correction. First, potential vertical line components detection consists of four steps, including edge detection for each connected component, pixel distance normalization in the edge, dominant-point detection in the edge and removal of horizontal components. Second, vertical line components detection is composed of removal of diagonal components and extraction of vertical line components. Third, the outline estimation step is composed of the left and right boundary line detection. Finally, distortion of the text image is corrected by bilinear transformation based on the estimated outline. We compared the changes in recognition rates of OCR before and after applying the proposed algorithm. The recognition rate of the distortion corrected signboard images is 29.63% and 21.9% higher at the character and the text unit than those of the original images.

데이퍼형 마이크로 스트립 선로에서 분산과 반사가 펄스의 왜곡에 미치는 영향 (An effects of the Pulse Distortion due to Dispersion and Reflection on Tapered Microstrip Line)

  • 김기래
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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    • pp.271-274
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    • 2000
  • In this paper, the distortion of an electrical pulse with rise/fall time resulting from dispersion and reflection as it propagates along a tapered microstrip line is investigated, and the delay time and distortion rate with respect to input and load impedances are analyzed on triangular and exponential tapered lines and analyzed the influence of the reflection and frequency dispersion on the distorted voltage wave in the tapered lines. The observed overshoot in front of the distorted wave is caused due to the frequency dispersion and the sustained tail of that comes from the reflection in the tapered line.

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얇은 박스형 용접구조물의 용접변형 해석 (Welding Distortion Analysis of a Laser Welded Thin Box Structure)

  • 김충기;김재웅;김기철
    • Journal of Welding and Joining
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    • 제25권5호
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    • pp.72-77
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    • 2007
  • Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin metal structure. In this study, numerical computations are performed to analyze effect of structure section shape and weld line location on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on bending deformation generated in outline welding of a thin box structure. From the numerical analysis, it was revealed that the section shape and weld line location play an important role on the welding distortion. Among 3 types of section shape design proposed in this study, the least deformation remained in the two path welded structure.

기하학적 불변성을 이용한 새로운 렌즈 보정 기법 (A New Method Using Geometric Invariability for Lens Distortion Correction)

  • 반 토안 카오;조상복
    • 대한전자공학회논문지SP
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    • 제48권6호
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    • pp.115-123
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    • 2011
  • 일반적으로 실제 사용되는 카메라들은 렌즈 왜곡이 존재하며, 렌즈왜곡의 정도는 카메라의 가격뿐만 아니라 특정 용도에 의해 달라진다. 현재까지의 많은 렌즈 왜곡 보정기법들은 왜곡 변수를 찾기 위해 투영 기하학의 불변량 속성을 기반으로 한 것으로, "물체의 직선은 이미지에서의 직선"이라는 상식에서 출발한다. 하지만, 평행선인 경우 이전의 연구들은 렌즈 왜곡 변수를 결정하는데 제약이 있다. 본 논문에서는 렌즈왜곡 변수를 결정할 때 동시에 평행선 유지를 보증할 수 있는 방법을 제안함으로써, 핀홀 카메라 모델을 이용하여 투영된 이미지와 실제 이미지가 근접한 결과를 얻게 된다. 실제 이미지와 제안된 기법을 사용한 보정이미지를 비교하여 그 효율성을 입증하였다.

지자기 센서의 온라인 왜곡 보정기법 (On-line Magnetic Distortion Calibration Method for a Magnetometer)

  • 김태연;소창주;유준
    • 제어로봇시스템학회논문지
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    • 제18권9호
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    • pp.819-822
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    • 2012
  • This paper describes an on-line magnetic distortion calibration procedure for a magnetometer. The horizontal magnetic field is calculated through the earth magnetic field sensed by 3-axes magnetometer. The ellipse equation is derived from a set of horizontal magnetic field data using least square method and calibration parameters are determined. The calibration process is performed iteratively until parameters are not renewed, and experimental results show the effectiveness of the devised method.

50kg/mm$^{2}$급 고장력 강판의 선상가열에 따른 판상변형과 재질변화 (Distortion and transformation of high tensile strength steel plate of 50kg/mm$^{2}$grade due to line heating)

  • 정남호;최병길;박종은
    • Journal of Welding and Joining
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    • 제3권1호
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    • pp.11-21
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    • 1985
  • The line heating is a thermoplastic working technique which is used in bending work of steel plate and in correcting the distortion of welded structure. This method is considerably effective when the water-cooling is followed. In this study, an investigation was accomplished to find the effects on the change of material properties when the line heating was applied on the high tensile steel plate of 50kg/mm^2$ grade. Some steel plates were heated to various temperatures and then cooled with water or in the air. In this study, the author measured the angular distortion continuously during line heating to find out the relation between the bending efficiency and heating or water-cooling temperature. Furthermore, its material properties were examined by the V-notch Charpy impact test, the microscope observation and the Vickers hardness test. As results, the followings were clarified. (1) The amount of angular distortion increases as the heating temperature or the water-cooling temperature rises. (2) When the steel plate is heated between 700.deg. C and 900.deg. C, and then is water-cooled over 700.deg. C, some brittle structure is observed. But if the temperature of water-cooling is below 700.deg. C, no brittle one is found. (3) When the steel plate is heated over 800.deg. C and is cooled in the air, there is no unfavrable effect.

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