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Hanjong Yoon,Younghoon Cho 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper studies the device current measurements, over-current detection and protection method using a Rogowski coil in a power conversion system using SiC MOSFET devices. And, switch current measurements and fault protection using the Rogowski coils have been proposed in other many papers. These papers protect the system by turning off the gate signal when a fault occurs, which causes propagation delays of several hundred ns. This paper proposes a method to reduce the propagation delay by shorting the gate-source when a fault occurs. Finally, the proposed over-current detection and protection method using the PCB pattern Rogowski coil has been verified through the experimental results.
Food Powder Classification Using a Portable Visible-Near-Infrared Spectrometer
Hanjong You,Youngsik Kim,Jae-Hyung Lee,Byung-Jun Jang,Sunwoong Choi 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.4
Visible-near-infrared (VIS-NIR) spectroscopy is a fast and non-destructive method for analyzing materials. However, most commercial VIS-NIR spectrometers are inappropriate for use in various locations such as in homes or offices because of their size and cost. In this paper, we classified eight food powders using a portable VIS-NIR spectrometer with a wavelength range of 450–1,000 nm. We developed three machine learning models using the spectral data for the eight food powders. The proposed three machine learning models (random forest, k-nearest neighbors, and support vector machine) achieved an accuracy of 87%, 98%, and 100%, respectively. Our experimental results showed that the support vector machine model is the most suitable for classifying non-linear spectral data. We demonstrated the potential of material analysis using a portable VIS-NIR spectrometer.
Performance Improvement of Block Turbo Coded OFDM System Using Channel State Information
Hanjong Kim 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
In this paper, we present a block turbo coded OFDM system. In case of OFDM system which makes use of block turbo codes or shorted block turbo codes as an error correcting code, we propose a new decoding algorithm which is better using the Channel State Information(CSI) in order to improve error correcting capability
Hanjong Shin,Han-Byoel Lee,Wonshik Han,Dong-Young Noh,Hyeong-Gon Moon 한국유방암학회 2015 Journal of Breast Disease Vol.3 No.2
Purpose: We aimed to evaluate the incidence of multifocal and bilateral lobular carcinoma in situ (LCIS) of the breast in Korean women. Add-itionally, we explored the characteristics of current breast imaging studies and evaluated their roles in detecting multifocal and bilateral lesions in LCIS patients. Methods: Between January 2000 and December 2013, we identified 48 patients with pure LCIS who underwent curative surgery at our institution. The pathological findings and the results of various imaging studies were reviewed. Results: All patients underwent mammography and ultrasonography prior to surgery, and 35 patients (72.9%) also received breast magnetic resonance imaging (MRI). The most common radiologic features of LCIS were the presence of microcalcifications (66.7%) and irregularly shaped masses (64.6%) on mammography and ultrasonography, respectively. MRI often showed the presence of irregularly enhanced mass-like lesions (91.4%). Add-itional suspicious lesions in the ipsilateral breast were identified in 19 (39.6%) and 16 (45.7%) patients on ultrasonography and MRI, respectively. Among them, nine (47.4%) were malignant lesions. In the contralateral breast, there were 14 (29.2%) and 11 (31.4%) lesions requiring biopsy on ultrasonography and MRI, respectively, and eight of these were found to be malignant lesions. All suspicious lesions detected by MRI were also seen on ultrasonography. In total, 20.8% (10/48) of the patients had ipsilateral LCIS, and 16.7% (8/48) had contralateral malignancies. Conclusion: Our study demonstrates that in Korean women, LCIS is associated with a high incidence of ipsilateral and contralateral malignancies. However, breast MRI had a limited role in detecting additional malignant tumors in LCIS patients.
Performance Evaluation of Channel Estimation in IEEE 802.11p WAVE System
Hanjong Kim 한국정보통신학회 2016 2016 INTERNATIONAL CONFERENCE Vol.8 No.1
In IEEE 802.11p WAVE System, more accurate channel estimation is necessarily required to improve communication performance. In this paper, a new channel estimation algorithm which is based on both two long training symbols and a short training symbol is presented to improve the performance of the existing LS channel estimation algorithm.
Three-Phase Current Balancing Strategy with Distributed Static Series Compensators
Hanjong Yoon,Dongkwan Yoon,Dongmin Choi,Younghoon Cho 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3
This paper proposes a three-phase current balancing strategy in a power transmission system employing distributed static series compensators (DSSCs). With the proposed variable quadrature voltage injection method, the DSSC emulates either an inductive or a capacitive impedance into the transmission line, and the magnitudes of the phase currents are balanced. Hence, the phase imbalances in the power transmission system are significantly reduced. As a result, the power transfer capability of the transmission lines can be improved. The operational principle of the DSSCs, the hardware structure and the control algorithm are described in detail. Finally, the theoretical analyses and the proposed strategy are experimentally verified through a scaled down transmission system with DSSC prototypes.