Shin J.-W.,Seoul National University |
Cho B.-H.,Seoul National University |
Lee J.-H.,Central R and nter
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2011
This paper proposes a digital average current mode control method in discontinuous conduction mode (DCM) power factor correction (PFC) rectifier. The proposed control technique can directly sense the average value of the inductor current in each switching cycle digitally by employing a conventional current sensing circuit. Thanks to the current control loop, high speed analog-to-digital converters (ADC's) or high performance digital IC's are not needed. The technique achieves lower total harmonic distortion (THD) and higher power factor (PF) than conventional DCM PFC rectifiers. Experimental results using prototype hardware verify the feasibility and performance of the proposed sensing method. © 2011 IEEE.
Yu M.,Shenyang Pharmaceutical University |
Shin Y.J.,Central R and nter |
Kim N.,Yonsei University |
Yoo G.,Yonsei University |
And 2 more authors.
Journal of Chromatographic Science | Year: 2015
A new method for the determination of six compounds, chlorogenic acid, rutin, nicotiflorin, hederacoside C, hederasaponin B and α-hederin, in ivy leaf extracts using high-performance liquid chromatography with diode array detector was developed. The chromatographic separation was performed on a YMC Hydrosphere C18 analytical column using a gradient elution of 0.1% phosphoric acid and acetonitrile. The method was validated in terms of specificity, linearity (r2 > 0.9999), precision [relative standard deviation (RSD) < 0.36%] and accuracy (97.4-103.8%). The limit of detection and limit of quantification were <20.32 and 61.56 ng for all analytes, respectively. The tested compounds were found to be stable in the ivy leaf extract from 0 to 48 h, and the RSD value for each compound was <0.90%. The validated method was successfully applied to quantify all six compounds in a 30% ethanol ivy leaf extract and 13 ivy leaf extract products. The results showed that all the tested products satisfied the minimum requirement for the content of hederacoside C. However, there were some differences between the contents of other constituents. © The Author 2014. Published by Oxford University Press.
Choi J.H.,Seoul National University |
Kuk J.G.,Seoul National University |
Kim Y.I.,Central R and nter |
Cho N.I.,Seoul National University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012
This paper proposes an algorithm for the detection of pillars or posts in the video captured by a single camera implemented on the fore side of a room mirror in a car. The main purpose of this algorithm is to complement the weakness of current ultrasonic parking assist system, which does not well find the exact position of pillars or does not recognize narrow posts. The proposed algorithm is consisted of three steps: straight line detection, line tracking, and the estimation of 3D position of pillars. In the first step, the strong lines are found by the Hough transform. Second step is the combination of detection and tracking, and the third is the calculation of 3D position of the line by the analysis of trajectory of relative positions and the parameters of camera. Experiments on synthetic and real images show that the proposed method successfully locates and tracks the position of pillars, which helps the ultrasonic system to correctly locate the edges of pillars. It is believed that the proposed algorithm can also be employed as a basic element for vision based autonomous driving system. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
Jeong S.H.,Central R and nter |
Choi C.G.,Central R and nter |
Oh J.N.,Central R and nter |
Yoon P.J.,Central R and nter |
And 3 more authors.
International Journal of Automotive Technology | Year: 2010
This paper presents a low cost design and implementation of a parallel parking assist system (PPAS) based on ultrasonic sensors. Generally, a PPAS requires several types of sensors, such as an ultrasonic sensor, camera sensor, radar sensor and laser sensor for parking space detection. However, our proposed PPAS only requires two ultrasonic sensors on the front and lateral sides for parking space detection. Moreover, a steering angle sensor and wheel speed sensor installed in the vehicle are used to obtain vehicle position information for localization in ultrasonic range data. The hardware architecture of the PPAS based on an electronic control unit (ECU) module, sensor modules and a human machine interface (HMI) module was proposed. Moreover, the software architecture of the PPAS is based on system initialization, scheduling, recognition and a control algorithm. In particular, a novel sensor algorithm was proposed to minimize the vehicle corner error of the ultrasonic sensor. A prototype of the PPAS based on the proposed architecture was constructed. The experimental results demonstrate that the implemented prototype is robust and successfully performs parking space detection and automatic steering control. Finally, the low cost design and implementation of the PPAS was possible due to the cheap ultrasonic sensors, simple hardware design and low computational complexity of the proposed algorithm. © 2010 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.