• Title/Summary/Keyword: PWM patterns

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Face Recognition and Notification System for Visually Impaired People (시각장애인을 위한 얼굴 인식 및 알림 시스템)

  • Jin, Yongsik;Lee, Minho
    • IEMEK Journal of Embedded Systems and Applications
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    • v.12 no.1
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    • pp.35-41
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    • 2017
  • We propose a face recognition and notification system that can transform visual face information into tactile signals in order to help visually impaired people. The proposed system consists of a glasses type camera, a mobile computer and an electronic cane. The glasses type camera captures the frontal view of the user, and sends this image to mobile computer. The mobile computer starts to search for human's face in the image when obstacles are detected by ultrasonic sensors. In a case that human's face is detected, the mobile computer identifies detected face. At this time, Adaboost and compressive sensing are used as a detector and a classifier, respectively. After the identification procedures of the detected face, the identified face information is sent to controller attached to a cane using a Bluetooth communication. The controller generates motor control signals using Pulse Width Modulation (PWM) according to the recognized face labels. The vibration motor generates vibration patterns to inform the visually impaired person of the face recognition result. The experimental results of face recognition and notification system show that proposed system is helpful for visually impaired people by providing person identification results in front of him/her.

New Fault Current Fast Shutdown Scheme for Buck Converter (벅 컨버터의 새로운 고장전류 고속차단 기법)

  • Park, Tae-Sik;Kim, Seong-Hwan
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.68-73
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    • 2019
  • This paper presents a novel fast shut-down scheme for Buck converter by using a coupled inductor. Generally, a controller for Buck converter stops generating PWM patterns in various fault cases: Overcurrent, Short circuit, or Overvoltage, but the inductor and capacitor keep supplying their stored energy to loads although the switching operations in Buck converter stopped. The stored energy in the inductor and capacitor could cause electrical stresses on breakers and safety problems. The main idea of the proposed fast shutdown scheme is to demagnetize the inductor core by using a coupled inductor, and its performance and operations are verified by using PSIM Simulation.