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류마티스 관절염의 활막 섬유모세포에서 Hypoxia/reoxygenation에 의한 종양 억제 인자 PTEN 발현의 조절
이학용 ( Hak Yong Lee ),류완희 ( Wan Hee Yoo ) 대한류마티스학회 2004 대한류마티스학회지 Vol.11 No.4
Objective: The lack of phosphatase and tensin homolgue deleted on chromosome ten (PTEN) expression was described in rheumatoid synovial tissues and synovial fibroblasts, but exact cause of that in RA is not well known. Hypoxic conditions are thought to exist in inflamed arthritic synovium and therefore, this study was designed to investigate the effects of hypoxia/reoxygenation on the expression of PTEN in synovial fibroblasts of rheumatoid arthritis. Methods: Synovial fibroblasts were isolated from synovial tissues of patients suffering from RA and hypoxic culture was performed by incubating cells in 5% CO2 incubator held at 3% oxygen by the addition of nitrogen gas for 24 hours. Then synovial fibroblasts were cultured for 10 min under normoxic condition for reoxygenation. To know the expression of PTEN and phosphorylated Akt (p-Akt) in synovial fibroblasts, Western blotting analysis was performed. The expression of PIP3 kinase and PTEN was analyzed by immunocytochemical staining. Results: There were less PTEN expression in rheumatoid synovial fibroblasts than that of healthy controls. Hypoxic/reoxygenation stimuli induced down-regulation of PTEN expression in the rheumatoid synovial fibroblasts. In contrast, the expression of PIP3 and p-Akt was increased after stimulation with hypoxia/reoxygenation. Conclusion: These studies suggest that hypoxia/reoxygenation could cause the reduced expression of PTEN in rheumatoid synovial fibroblasts and thus it might thereby contribute to the invasive behaviour of rheumatoid synovial fibroblasts by maintaining their aggressive phenotype in RA.
단일 도파관 급전된 캐비티 장착 서브어레이를 이용한 고효율 슬롯 배열 안테나
정강재,이학용,박면주,이병제,Jung Kangjae,Lee Hak-Yong,Park Myun-Joo,Lee Byungje 한국전자파학회 2004 한국전자파학회논문지 Vol.15 No.12
본 논문에서는 무궁화 3호 위성의 방송수신용 안테나를 설계 및 제작하였는데, 기존의 방송수신용 안테나보다 넓은 수신영역을 가지는 고이득 안테나를 제작하는데 중점을 두었다. 본 안테나는 급전 라인의 손실을 줄이기 위하여 급전 라인을 도파관 구조로 설계하였다. 또한 방사효율을 높이고 급전 구조를 간단히 하기 위하여 cavity backed slot array 형태의 방사구조를 제안하였다. 슬롯 배열 안테나의 최대 이득은 11.7 GHz$\~$12.75 GHz 대역에서 33 dEi 이상을 얻을 수 있었다. 임피던스 대역폭 또한 VSWR 2:1에서 $13\%$로 설계사양을 만족시켰다. The antenna array for receiving satellite broadcasting of Koreasat III is proposed. A cavity-backed slot antenna array is proposed to reduce feed line loss, increase the radiation efficiency, and make the feed network simple. A sub-array consists of $2{\times}4$ slot elements backed by a single cavity. By proper choice of dimensions it is shown that the proposed antenna has characteristics of the high radiation efficiency and the broad frequency bandwidth. Antenna characteristics for the array antenna with 256 elements are measured in Ku-band. A single cavity backed-sub-array has the gain of 18 dEi. The gam of the total antenna array(256 elements) is Over 33 dEi.
위성 DMB 중계기용 Cavity-Backed슬롯 배열 안테나
정희철,이학용,정병운,강기조,박면주,이병제,Jung Hee-Chul,Lee Hak-Yong,Jung Byungwoon,Kang Gi-Cho,Park Myun-Joo,Lee Byungje 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.4
This paper presents analysis of a slot array antenna having a low side lobe level and high front-to-back ratio for a repeater system of a satellite DMB(Digital Multimedia Broadcasting) service. Antennas for this repeater system require a high gain and enough isolation to reduce interferences between signals in system. Therefore, it is necessary to suppress a side lobe level and to increase front-to-back ratio. Unlike a structure 134 by lossy microstrip lines, in this work a single cavity-backed slot antenna array using a single waveguide feed is proposed to obtain the reliability for high power handling and high radiation efficiency. The side lobe level and front-to-back ratio are enhanced with tapered array technique and an optimized vertical reflector. The measured side lobe levels in H- and E-plane are under $-33.24\;\cal{dB}$ and $-35.78\;\cal{dB}$, respectively. The front-to-back ratio over $37.84\;\cal{dB}$, and the peak gain of over $17\;\cal{dBi}$ are measured.