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Effect of Magnetic Stimulation in Spinal Cord on Limb Angiogenesis and Implication: A Pilot Study
Dohong Lee,서관식,범재원,Byung-Mo Oh 대한재활의학회 2012 Annals of Rehabilitation Medicine Vol.36 No.3
Objective To investigate the eff ect of repetitive magnetic stimulation (rMS) of the spinal cord on limb angiogenesis in healthy rats and explore its implication for the treatment of lymphedema. Method Twelve adult male Sprague-Dawley rats were divided into four groups as follows: sham rMS followed by tissue harvest 5 minutes later (group 1, n=2), 1 Hz rMS and tissue harvest 5 minutes later (group 2, n=3), 20 Hz rMS and tissue harvest 5 minutes later (group 3, n=3), 20 Hz rMS and tissue harvest 30 minutes later (group 4, n=4). Animals were treated with 20-minute rMS with 120% of the motor threshold on their left side of upper lumbar spinal cord. Expression of angiogenic factors, that is, Akt, phospho-Akt (pAkt), endothelial nitric oxide synthase (eNOS), phospho-eNOS (p-eNOS) were measured by western blot. Bilateral hindlimb muscles (quadriceps and gastrocnemius) were harvested. Results Expression of Akt in left quadriceps increased in group 4 compared with group 2 and 3 (3.4 and 5.3-fold each, p=0.026). Expression of eNOS in left plus right quadriceps markedly increased in group 3 and 4 compared with group 1 and 2 (p=0.007). Expressions of eNOS, Akt and p-eNOS, pAkt in gastrocnemius were not comparable between four groups (p>0.05). Conclusion Repetitive magnetic stimulation of the spinal cord may exert an angiogenic eff ect closely linked to lymphangiogenesis. It has clinical implication for the possible therapy of lymphedema caused by breast, cervical or endometrial cancer operation. Future studies with the specifi c lymphatic endothelial cell markers are required to confi rm the eff ect of rMS on lymphangiogenesis.
Highly isolated switching mode power supply for solid-state transformers in railway vehicles
Lee, Yejun,Bu, Hanyoung,Lee, Dohong,Cho, Younghoon The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.4
This paper discusses an isolated switching mode power supply (SMPS) with an AC 30 kV<sub>rms</sub> insulation capability for application to the solid-state transformers (SSTs) in railway vehicles. The insulation capability of the SMPS should be higher than AC 25 kV<sub>rms</sub> for application at the SSTs in railway vehicles. The proposed highly isolated SMPS is superior to commercial isolated power supplies with low insulation capability, which is normally less than 20 kV. The input side of the proposed isolated SMPS is physically separated from its output side by a specially designed miniature high-frequency (HF) transformer to obtain high insulation capability. The core of the miniature HF transformer is separated by insulation material. The primary and secondary coils are wound around each separated core. A CLLC resonant converter that consists of a primary resonant capacitor (C), two inductors (LL), and a secondary resonant capacitor (C) is applied as the proposed isolated SMPS topology to improve the output voltage regulation performance, which varies due to a large leakage inductance derived from the airgap of the proposed miniature HF transformer. Experiments are carried out to verify the CLLC resonant converter of the proposed isolated SMPS. Electrostatic finite element method (FEM) simulations and high potential (HiPot) tests are carried out to verify the AC 30 kV<sub>rms</sub> insulation capability of the proposed isolated SMPS. The electrostatic FEM simulations demonstrate the DC 42.43 kV insulation capability, and the HiPot tests verify the insulation capability from AC 5 kV<sub>rms</sub> to AC 30 kV<sub>rms</sub>.
전기차 급속충전기 적용을 위한 50kW급 3상 Hybrid ANPC 컨버터
이도홍(Dohong Lee),이성민(Sungmin Lee),조영훈(Younghoon Cho),복영한(Bonggook Kim),김봉국(Younghan Bok) 전력전자학회 2021 전력전자학술대회 논문집 Vol.2021 No.7
본 논문에서는 50kW급 3상 Hybrid ANPC 컨버터의 동작 원리와 PWM 기법을 분석하고 구현한다. Hybrid ANPC 컨버터는 기존의 3레벨 회로구조 중 하나인 Si 소자 기반의 ANPC 컨버터의 일부 SiC 소자로 대체한 회로구조이다. Hybrid ANPC 컨버터는 기존의 SiC ANPC 컨버터에 비해 비용이 저렴하고, Si ANPC 컨버터에 비해 전체 손실이 적다는 장점이 있다. 본 논문에서는 Hybrid ANPC 컨버터의 동작원리 및 PWM 기법에 관한 내용을 분석하고, Hybrid ANPC 컨버터의 모듈레이터 구현에 대해 설명한다. 또한, 이를 검증하기 위해 50kW급 3상 Hybrid ANPC 컨버터를 구현하여 실험을 진행하였다.
Kwon, Seonil,Kim, Hyuncheol,Choi, Seungyeop,Jeong, Eun Gyo,Kim, Dohong,Lee, Somin,Lee, Ho Seung,Seo, Young Cheol,Choi, Kyung Cheol American Chemical Society 2018 Nano letters Vol.18 No.1
<P>Fiber-based wearable displays, one of the most desirable requisites of electronic textiles (e-textiles), have emerged as a technology for their capability to revolutionize textile and fashion industries in collaboration with the state-of-the-art electronics. Nonetheless, challenges remain for the fibertronic approaches, because fiber-based light-emitting devices suffer from much lower performance than those fabricated on planar substrates. Here, we report weavable and highly efficient fiber-based organic light-emitting diodes (fiber OLEDs) based on a simple, cost-effective and low-temperature solution process. The values obtained for the fiber OLEDs, including efficiency and lifetime, are similar to that of conventional glass-based counterparts, which means that these state-of-the-art, highly efficient solution processed planar OLEDs can be applied to cylindrical shaped fibers without a reduction in performance. The fiber OLEDs withstand tensile strain up to 4.3% at a radius of 3.5 mm and are verified to be weavable into textiles and knitted clothes by hand-weaving demonstrations. Furthermore, to ensure the scalability of the proposed scheme fiber OLEDs with several diameters of 300, 220, 120, and 90 μm, thinner than a human hair, are demonstrated successfully. We believe that this approach, suitable for cost-effective reel-to-reel production, can realize low-cost commercially feasible fiber-based wearable displays in the future.</P> [FIG OMISSION]</BR>