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Split-Ring 공진기와 Spiral 공진기를 이용한 새로운 소형의 마이크로스트립 대역 저지 필터 설계
이종혁,오영철,명로훈,Lee, Jong-Hyuk,Oh, Young-Chul,Myung, Noh-Hoon 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.7
이 논문에서는 split-ring 공진기와 spiral 공진기를 complementary 형태로 구현한 새로운 형태의 두 가지 마이크로스트립 대역저지 필터를 제안하였다. 첫 번째는 마이크로스트립 전송 선로의 중앙 선로에 세 개의 split-ring 공진기를 일렬로 배열시켜 에칭 시킨 것이다. 중앙 선로에 구현된 세 개의 split-ring 공진기와 수직으로 시간에 따라 변하는 전계가 걸리면 특정 공진 주파수에서 유효 투자율이 음이 되는 현상이 벌어지며, 이에 따라 전파가 더 이상 진행하지 못하게 된다. 이는 특정 공진 주파수에서 대역저지 현상이 나타나는 것을 의미한다. 두 번째는 첫 번째 것과 비슷하게 마이크로스트립의 중앙 선로에 spiral 공진기를 세 개 나열하여 에칭하였다. Spiral 공진기는 그 축에 수직한 방향으로 전계가 걸렸을 때 특정 공진 주파수에서 self-resonance 현상이 일어나며, 이것이 대역저지 특성으로 나타난다. 제안된 두 필터는 쉽게 공진 주파수와 대역저지 폭을 결정할 수 있고, 매우 작은 크기를 갖으며, 통과대역 내에서 삽입손실이 거의 없으며, 매우 날카로운 스커트 특성을 갖는다. 또한 제작하기 쉽고, 향후 MMIC에 적용하기 쉬울 것으로 예상한다. In this paper, two novel compact microstrip bandstop filters using complimentary split ring resonators(CSRRs) and spiral resonators is proposed. The first one is the bandstop filter using an array of CSRRs etched on the center line of a microstrip. The bandstop is due to the presence of negative effective permittivity and positive permeability near resonant frequency which prevent the wave propagation. The second on is the bandstop filter using an array of spiral resonators etched on the center line of a microstrip. The bandstop is due to the self-resonance of spiral circuit. We have achieved controllable resonance frequency and bandwidth, super compact dimension, low insertion losses in the passband and high level of rejection in the stopband with sharp cutoff. The electrical sizes of two proposed filter are very small. Additionally, they can be easily fabricated and compatible with MMIC or PCB technology.
CUPID코드를 활용한 2×2 봉다발 부수로 내부 단상 및 2상 난류유동 해석
이종혁,박익규,이재룡,김정우,Lee, Jong Hyuk,Park, Ik Kyu,Lee, Jae Ryong,Kim, Jungwoo 한국전산유체공학회 2017 한국전산유체공학회지 Vol.22 No.4
It is important to understand the flow characteristic in a subchannel of nuclear rod bundle in the design process of a nuclear reactor considering the safety margin. In this study, the CUPID code was used to simulate the flow phenomena in the $2{\times}2$ rod bundle. The simulation of $2{\times}2$ rod bundle test under single- and two-phase flow conditions were conducted to validate the turbulence model. The liquid velocities at 0.45 m along the flow path with 0 and 45 degree of azimuthal angle were compared with experimental data. The CUPID results were a good agreement with experimental data, though the ones for 0 degree case has a little discrepancy. For the future work, the turbulent flow will be investigated by applying different turbulence models to improve the prediction of velocity near wall.
이종혁,Choi Eun Jung,Han Seok Cheol,Chung Hee Sup,권미정,Jayaram Prathap,Lee Wonjae,Michael Y.Lee 대한초음파의학회 2021 ULTRASONOGRAPHY Vol.40 No.4
Purpose: The purpose of this study was to compare the efficacy of low-dose steroid, highdose steroid, and low-dose steroid combined with hyaluronidase with respect to intra-articular injection therapy for adhesive capsulitis (AC) of the shoulder. Methods: Thirty patients with primary AC in the initial stage were randomly assigned into three groups to receive ultrasound-guided intra-articular injections with 20 mg of triamcinolone acetonide (group A, n=10), 40 mg of triamcinolone acetonide (group B, n=10) and 20 mg of triamcinolone acetonide combined with hyaluronidase (group C, n=10). The outcome measures included a visual analogue scale (VAS), the Shoulder Disability Questionnaire (SDQ), abduction and external rotation range of motion, and intra-sheath fluid (ISF) before treatment and at 2, 4, 8, and 16 weeks after treatment. Results: Among the 30 patients, one participant in group B dropped out; therefore, a total of 29 patients completed this study and were successfully injected. After the injection, the VAS, SDQ, range of flexion and external rotation, and ISF improved in all groups compared with the preinjection status, regardless of treatment or time point. In the comparison between groups, the SDQ and ISF showed significantly greater improvements in groups B and C than in group A. Conclusion: The therapeutic efficacy of combined low-dose corticosteroid and hyaluronidase is superior to that of low-dose corticosteroid and equivalent to that of high-dose corticosteroid in early AC. Purpose: The purpose of this study was to compare the efficacy of low-dose steroid, highdose steroid, and low-dose steroid combined with hyaluronidase with respect to intra-articular injection therapy for adhesive capsulitis (AC) of the shoulder.Methods: Thirty patients with primary AC in the initial stage were randomly assigned into three groups to receive ultrasound-guided intra-articular injections with 20 mg of triamcinolone acetonide (group A, n=10), 40 mg of triamcinolone acetonide (group B, n=10) and 20 mg of triamcinolone acetonide combined with hyaluronidase (group C, n=10). The outcome measures included a visual analogue scale (VAS), the Shoulder Disability Questionnaire (SDQ), abduction and external rotation range of motion, and intra-sheath fluid (ISF) before treatment and at 2, 4, 8, and 16 weeks after treatment.Results: Among the 30 patients, one participant in group B dropped out; therefore, a total of 29 patients completed this study and were successfully injected. After the injection, the VAS, SDQ, range of flexion and external rotation, and ISF improved in all groups compared with the preinjection status, regardless of treatment or time point. In the comparison between groups, the SDQ and ISF showed significantly greater improvements in groups B and C than in group A.Conclusion: The therapeutic efficacy of combined low-dose corticosteroid and hyaluronidase is superior to that of low-dose corticosteroid and equivalent to that of high-dose corticosteroid in early AC.
이종혁,김병규 한국디지털콘텐츠학회 2017 한국디지털콘텐츠학회논문지 Vol.18 No.1
Scalable extension of High Efficiency Video Coding (SHVC) standard uses the up-sampled residual data from the base layer to make a residual data in the enhancement layer. This paper describes an efficient algorithm for improving coding gain by using the filtered residual signal of base layer in the Scalable extension of High Efficiency Video Coding (SHVC). The proposed adaptive filter selection mechanism uses the smoothing and sharpening filters to enhance the quality of inter-layer prediction. Based on two filters and the existing up-sampling filter, a rate-distortion (RD)-cost fuction–based competitive scheme is proposed to get better quality of video. Experimental results showed that average BD-rate gains of 1.5%, 2.1%, and 1.7% for Y, U and V components, respectively, were achieved, compared with SHVC reference software 5.0, which is based on HEVC reference model (HM) 13.