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다층 구조를 이용한 도파관 배열의 EMP 차폐성능과 유동 분석
김상인(Sangin Kim),김유나(Yuna Kim),방승기(Seung-Ki Pang),김석봉(Suk-Bong Kim),육종관(Jong-Gwan Yook) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.8
배기관에 도파관 배열을 삽입하여 일정수준의 차폐효과를 만족시키기 위해서는 도파관 배열의 전체길이가 늘어나야 한다. 이때, 공정의 난이도와 비용이 증가하게 되며, 유체의 흐름을 방해하게 된다. 이를 보완하기 위해, 여러 개의 도체판으로 접합시켜 만든 도파관을 교차시켜 다층 구조 도파관을 제안하였다. 2층 구조에서부터 8층 구조까지 증가시키며, 차폐효과를 확인한 결과, 52 dB에서 75 dB로 향상되는 것을 확인하였다. 또한, 다층 구조 도파관이 설치된 배기관에 대해서 유속 시뮬레이션을 진행한 결과, 주입구 유속이 1m/s일 경우, 2층 구조에서부터 8층 구조까지 입구 및 출구 측 유속이 각각 0.88m/s에서 0.77m/s, 0.68m/s에서 0.68m/s로 단일 사각형 도파관 배열의 유속 결과 값인 0.79 m/s와 0.53m/s에 비해서 속도 손실이 줄어드는 것을 확인하였다. Increasing the total length of waveguide-below-cutoff array(WBCA) as it is used to the duct in order to enhance shielding effectiveness, the design could cause higher cost, higher levels of difficulties in construction and the interruption a flow velocity. The multi-layered WBCA can compensate for this problem, which can be designed by crossing each waveguide layer. By conducting simulations from 2-layer to 8-layer structure, it can be observed that the shielding effectiveness increases from 52 dB to 75 dB. Comparing with the original WBCA in a shape of mono layer rectangular, our proposed waveguide becomes similar with the original value as the number of crossing layer increases. In addition, the analysis with the flow of fluid in the duct installed multi-layered WBCA are required. We demonstrate this analysis by doing the flow of fluid simulation, and concluded that the multi-layered WBCA has loss of flow of fluid less than unit rectangular WBCA.
블루레이 플레이어 Console용 Touch Pad의 전원 노이즈 해석에 관한 연구
김상인(Sangin Kim),김종민(Jongmin Kim),김병기(Byungki Kim),나완수(Wansoo Nah) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
전자기기에서 외부 Console로 사용되는 Touch Pad의 입력오류를 줄이기 위해서는 안정된 전원의 공급이 필요하다, 전원에서 발생하는 노이즈는 PDN(Power Delivery Network)의 임피던스에 의해서 발생하며, 이들 노이즈를 줄이기 위해서는 decoupling capacitor의 적절한 수량과 위치를 선정하여, PDN의 임피던스를 최소화해야 한다. 본 논문에서는 임피던스의 최소화를 위해서 Full-wave 시뮬레이션을 이용해서 임피던스 특성을 분석하고, VNA(Vector Network Analyzer)를 이용하여 주파수에 대한 PDN 임피던스를 측정하고, Touch Pad 구동용 지그를 이용해서 Time Domain에서의 임피던스 저감에 따른 노이즈 특성을 분석 비교하였다.
Kim Hyeon Seong,Park Jae Hyeon,Lee Ho Seok,Lee Jae Young,Jung Ji Won,Park Si-Bog,Hyun Dong Jin,Park Sangin,Yoon JuYoung,Lim Hyunseop,Choi Yun Young,Kim Mi Jung 대한의학회 2021 Journal of Korean medical science Vol.36 No.12
Background: Spinal cord injury (SCI) is a serious clinical condition that impacts a patient's physical, psychological, and socio-economic status. The aim of this pilot study was to evaluate the effects of training with a newly developed powered wearable exoskeleton (Hyundai Medical Exoskeleton [H-MEX]) on functional mobility, physiological health, and quality of life in non-ambulatory SCI patients. Methods: Participants received 60 minutes of walking training with a powered exoskeleton 3 times per week for 10 weeks (total 30 sessions). The 6-minute walking test (6MWT) and timed-up-and-go test (TUGT) were performed to assess ambulatory function. The physiological outcomes of interest after exoskeleton-assisted walking training were spasticity, pulmonary function, bone mineral density, colon transit time, and serum inflammatory markers. Effects of walking training on subjective outcomes were estimated by the Korean version of the Falls Efficacy Scale—International and the 36-Item Short-Form Health Survey version 2. Results: Ten participants finished 30 sessions of training and could ambulate independently. No severe adverse events were reported during the study. After training, the mean distance walked in the 6MWT (49.13 m) was significantly enhanced compared with baseline (20.65 m). The results of the TUGT also indicated a statistically significant improvement in the times required to stand up, walk 3 m and sit down. Although not statistically significant, clinically meaningful changes in some secondary physiological outcomes and/or quality of life were reported in some participants. Conclusion: In conclusion, this study demonstrated that the newly developed wearable exoskeleton, H-MEX is safe and feasible for non-ambulatory SCI patients, and may have potential to improve quality of life of patients by assisting bipedal ambulation. These results suggest that the H-MEX can be considered a beneficial device for chronic non-ambulatory SCI patients.
Kim, Myunghwan,Jeong, Chang Yeong,Heo, Hyungjun,Kim, Sangin Optical Society of America 2015 Optics letters Vol.40 No.6
<P>We propose a high-performance, graphene-based optical modulator with a surface plasmon resonance (SPR) at 1550?nm. In the proposed device, a graphene layer is embedded in a hybrid plasmonic waveguide to enhance the light-graphene interaction. The adjustment of the permittivity of the graphene causes a significant modulation of the absorption in the SPR through a variation of the field confinement in the graphene layer, in addition to a resonant angle shift. With an optimal thickness of a metal (Ag) film and the properly chosen operation point of the Fermi level of graphene, a modulation depth of 100% was achieved. As the number of graphene layers in the proposed device increases, the insertion loss decreases. With five-layer graphene, a 6% insertion loss was achieved.</P>
Modified Shielding Effectiveness Equation for Novel Multilayered Waveguide-Below-Cutoff Array
Kim, Sangin,Kim, Yuna,Pang, Seung-Ki,Yook, Jong-Gwan Professional Technical Group on Microwace Theory a 2018 IEEE transactions on microwave theory and techniqu Vol.66 No.9
<P>This paper presents an airflow analysis and a shielding effectiveness (SE) analysis for a multilayered waveguide-below-cutoff array (WBCA) used to prevent electromagnetic penetration. The performance of the conventional unit square WBCA and the multilayered WBCA is compared. For the airflow analysis, the simulations are performed at the entrance and exit of the shielding structure when an airflow velocity of 1 m/s is injected at the inlet. The velocity loss and pressure difference of the multilayered WBCA are improved compared with the unit square WBCA. In terms of the shielding, the SE of the multilayered WBCA is compensated by increasing the number of overlapping layers. Furthermore, a new SE equation is derived by modifying that of the unit square WBCA.</P>
Low bending loss characteristics of hybrid plasmonic waveguide for flexible optical interconnect
Kim, Jin Tae,Park, Suntak,Ju, Jung Jin,Lee, Sangjun,Kim, Sangin The Optical Society 2010 Optics express Vol.18 No.23
<P>The bending loss characteristics of the hybrid plasmonic waveguide are investigated theoretically and experimentally. Simulation results showed that the guided mode is confined mainly into outer high index slab as the bending radius decreases. Thus, the radiation loss due to bending is greatly suppressed. We fabricate flexible hybrid plasmonic waveguide consisted of 5 nm-thick Au stripe and flexible multiple polymer cladding layers. The measured bending loss is lower than 1 dB/180° at a wavelength of 1310 nm for the bending radii down to 2 mm.</P>