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Doohyung Kang,Mincheol Shin IEEE 2015 IEEE transactions on magnetics Vol.51 No.7
<P>The synchronization of spin torque nano-oscillators (STNOs) is studied by the parallel circuit model for the giant magnetoresistance pillar. Employing a macrospin simulation approach, we obtain a synchronization range in the plane of the frequency and the resistance for various capacitances. The region of the synchronization is found to be extended by introducing capacitors and to be robust against magnetic anisotropy field fluctuations. We discuss calculated results to improve the synchronization between STNOs.</P>
Correlation between Severity of Synovitis and Clinical Features in Rotator Cuff Tears
Doohyung Lee,Kwang-Hyun Lee,Jo Young-Hoon,Il-Han Joo,Hee Jae Lee,Soo-Young Jeong,Bong Gun Lee 대한정형외과학회 2021 Clinics in Orthopedic Surgery Vol.13 No.1
Background: Rotator cuff tears can be asymptomatic in some cases; however, even when the tear size is small, clinical symptoms can be very severe. This suggests that symptoms of rotator cuff tears are related to factors other than the size. Although synovitis has been cited as one of the factors, there is no grading system for synovitis in rotator cuff tears. Moreover, there are few studies that evaluated the relationship between synovitis and clinical features in patients with rotator cuff tears. Methods: Patients with medium-sized rotator cuff tears, who were scheduled for arthroscopic repair, were recruited for this study. The glenohumeral joint was divided into 4 quarters. Then, vascularity and hypertrophy of the joint were graded in each quarter using a modified scoring system. Clinical assessment was performed preoperatively and at 3 months and 6 months after surgery. Finally, correlation between the severity of synovitis and clinical features was analyzed. Results: The intraobserver correlation coefficient was 0.815 to 0.918 and the interobserver correlation coefficient was 0.779 to 0.992 for the single measurement. Vascularity was significantly correlated with the range of motion, strength, and constant score within 6 months after surgery. Hypertrophy was correlated with the range of motion within 6 months after surgery. Conclusions: Synovitis in the shoulder with rotator cuff tears can be graded by using our modified scoring system. The severity of synovitis was closely related to the clinical features after surgery. Therefore, when treating patients with rotator cuff tears, treatment of synovitis should also be considered.
A Novel Structure for the Improved Switching Time of 50V Class Vertical Power MOSFET
Cho, Doohyung,Park, Kunsik,Kim, Kwangsoo Institute of Korean Electrical and Electronics Eng 2015 전기전자학회논문지 Vol.19 No.1
In this paper, a novel trench power MOSFET using a Separate-W-gated technique MOSFET (SWFET) is proposed. Because the SWFET has a very low $Q_{GD}$ compared to other forms of technology, it can be applied to high-speed power systems. The results found that the SWFET-applied $Q_{GD}$ was decreased by 40% when compared to simply using the more conventional trench gate MOSFET. $C_{ISS}$ (input capacitance : $C_{GS}+C_{GD}$), $C_{OSS}$ (output capacitance : $C_{GD}+C_{DS}$) and $C_{RSS}$ (reverse recovery capacitance : $C_{GD}$) were improved by 24%, 40%, and 50%, respectively. The switching characteristics of the inverter circuit shows a 24.9% enhancement of reverse recovery time, and the power efficiency of the DC-DC buck converter increased by 14.2%. In addition, the proposed SWFET does not require additional process steps and There was no degradation in the electrical performance of the current-voltage and on-resistance.
펄스파워용 고전압 MCT (MOS Controlled Thyristor) 소자 제작 및 특성 평가
조두형(Doohyung Cho),원종일(Jong il Won),권성규(Sungkyu Kwon),정동윤(Dongyun Jung),장현규(Hyungyu Jang),이성현(Seong Hyun Lee),임종원(Jong-Won Lim),박건식(Kunsik Park) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6
ETRI DMC Convergence Research Department designed and fabricated MCT devices for pulse power systems. in this paper, we evaluated the electrical characteristics of the fabricated 1400V and 2500V class MCT devices. As a result, the 1400V class MCT device achieved a breakdown voltage of 1815V, and on/off-FET V<sub>Th</sub> achieved 0.9V/-0.5V. Additionally, the 2500V class MCT device achieved a breakdown voltage of 3150V, and on/off-FET V<sub>th</sub> achieved 1.1V/-1.0V respectively.