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서무현(Mu-Hyun Seo),장리검(Li-Jian Jhang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.8
This paper presents a 2.45-GHz shorted patch antenna suitable for the ZigBee communication in railway environments. The proposed antenna consists of a shorted patch fed by a coaxial line, an 1-mm thick FR-4 substrate radome with the patch printed on the back surface and a metal cavity. The patch is shorted using one of the cavity walls and matched in impedance by connecting the coaxial probe at a suitable point in the patch length direction. The length and width of the patch are 27.6mm(0.225λ<SUB>0</SUB>) and 21.0mm(0.172λ<SUB>0</SUB>) respectively. The whole antenna structure including the metal cavity and the coaxial feed line is optimized, fabricated and measured. Measurements show that the proposed antenna has a 4.0-dBi gain at 2.45GHz and a reflection coefficient of less than -10dB at 2.375-2.525GHz.
서무현 ( Mu Hyun Suh ),안병철 ( Bierng Chear Ahn ) 충북대학교 산업과학기술연구소 2014 산업과학기술연구 논문집 Vol.28 No.2
This paper presents a near-field reader antenna operating in the UHF band(850-1000MHz). The antenna consists of 2 x 2 planar inverted F antennas(PIFAs). A dual polarized radiation is achieved by placing PIFAs in orthogonal directions. Four PIFA elements are used to detect RFID tags irrespective of their orientations. PIFA elements are placed in a metal cavity with a dimension of 200x200x25mm3. Four PIFA elements are sequentially driven by a four-port RFID reader providing the polarization and space diversity. The designed antenna is fabricated and tested. Measurements show that the single PIFA element has a gain of 3.2dB and a reflection coefficient of less than -10dB at 820-938MHz and that the 4-element reader antenna can detect a credit card type tag at distances up to 56cm above the antenna surface irrespective of the tag orientation.
서주영,서무현,안병철 충북대학교 컴퓨터정보통신연구소 2015 컴퓨터정보통신연구 Vol.23 No.2
This paper presents a design of a wideband dual-polarized patch antenna operating at the VHF band. The designed antenna consists of a four-slitted patch at four points by capacitive coupling and a parasitic patch. A wideband performance of the antenna is obtained by increasing the distance between the fed patch and the ground plane, and a parasitic patch. The designed antenna has a gain of 4.4dB at 200MHz and a reflection coefficient of less than -6dB over 165-260MHz.
RAW 264.7 세포에서 silica에 의한 염증 반응에 미치는 calcium chelator의 영향
심상수,이승준,서무현,김창종 중앙대학교 약학연구소 2001 약학 논총 Vol.15 No.-
To investigate the action of calcium in silica-induced inflammatory response, we observed examined effect of calcium chelator on arachidonic acid (AA) release, reactive oxygen species (ROS) and peroxynitrite (PON) in RAW 264.7 cells stimulated by silica dose-dependently increased [^3H]AA release, ROS and PON generation. Extracellular Ca^2+ chelator, EGTA, dose dependently inhibited silica-induced AA release and PON generation, but did not affect ROS generation. Intracellular Ca^2+ chelator, BAPTA, significantly inhibited ROS and PON generation but did not have any influence on AA release. These results suggest that PON generation is associated with both extracellular Ca^2+ influx and intracellular Ca^2+ release, whereas AA release and ROS generation is related to extracellular CA^2+ influx and intracellular Ca^2+ release in RAW 264.7 cells, respectively.
비만세포에서 Histamine유리에 관여하는 Phospholipase $A_2$의 작용
이윤혜,이승준,서무현,장용운,윤정이 대한약학회 2001 약학회지 Vol.45 No.3
To investigate whether phospholipase $A_2$pathway is involved in histamine release of rat peritoneal mast cells, we measured histamine release in the presence of various enzyme inhibitors involved in eicosanoid pathway, such as phospholipase $A_2$, cyclooxygenase and lipoxygenase. Phospholipase $A_2$inhibitors, manoalide and OPC, significantly inhibited histamine release induced by 100 $\mu$M ATP and 1$\mu$g/ml compound 48/80. Cyclooxygenase inhibitors, ibuprofen and indomethacin, significantly inhibited ATP-induced histamine release and lipoxygenase inhibitors, baicalein and caffeic acid, also significantly inhibited. To investigate the involvement of protein kinase in ATP- and compound 48/80-induced histamine release, we observed effects of protein kinase inhibitors on histamine release. Bisindolmaleimide (protein kinase C antagonist) dose-dependently inhibited both ATP and compound 48/80-induced histamine release. Tyrosine kinase inhibitors (methyl 2,5-dihydroxy cinnamate and genistein) dose-dependently inhibited ATP and compound 48/80-induced histamine release. Protein kinase C and tyrosine kinase seem to be involved in histamine release induced by ATP and compound 48/80. These results suggest that phospholipase $A_2$pathway as well as protein kinase C and tyrosine kinase are involved in histamine release of rat peritoneal mast cells by ATP and compound 48/80.
군용항공기 기초 스텔스 설계를 위한 엔진 배기가스 적외선 신호 해석 및 검증
정환,김민석,김태훈,박찬서,서무현,김혜민 한국추진공학회 2023 한국추진공학회지 Vol.27 No.2
During the development process of an aircraft system, infrared stealth design was performed and a technique was developed and validated for analyzing infrared emissions from engine exhaust gases. Ansys Fluent was used to analyze the thermal flow of the engine exhaust gases and the obtained data on material fraction and temperature field was used to interpret infrared signals using the RADCAL program. To validate the results of the analysis, a comparison was made with existing experimental results using a micro-turbine engine, and it was confirmed that, despite a slightly lower spatial resolution than the experimental results, a high level of accuracy was achieved.
2.4-GHz ZigBee 통신용 원편파 패치 안테나 최적 설계 및 구현
홍기표(Ki-Pyo Hong),노재우(Jae-Woo Noh),서무현(Mu-Hyun Seo),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.8
A communication path between a sensor node installed underneath a railway cabin and a sensor node installed inside a cabin is a non-line-of-sight link with a high degree of polarization rotation, in which case circularly polarized antennas are advantageous. This paper presents a circularly-polarized patch antenna for a ZigBee sensor node operating inside a railway cabin. The proposed antenna consists of a rectangular patch, a patch feed circuit, and a metal case. An FR-4 circuit board is employed as a radome by using it as a lid of the metal case and by printing the patch on its backside. The patch feed circuit is realized with a power divider and a 90° phase delay line in a GCPW having low radiation and placed beneath the patch circuit board. Measurements show that the proposed antenna has a gain of 7.5dB and an axial ratio of 3dB at 2.45GHz, and a reflection coefficient of less than -10dB at 2.4-2.5GHz.