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열습환경을 고려한 항공기용 레이돔 볼트 체결부의 베어링 강도에 관한 연구
김호일(Kim Hoil),유구현(Ryu Guhyun),김준(Kim Joon),이규송(Lee Kyusong),박영주(Park Youngju),박범준(Park Byumjun),유홍균(Ryu Hongkyun) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
This research investigated the hygrothermal effect on the strength of the bolt jointed section and moisture contents of composites exposed to hygrothermal environment for composite aircraft radome. The decrease in the strength by testing environments is mainly attributed to the change of the material properties of matrix by temperature and moisture. The composite specimens were tested in three different environmental conditions of RTD(room temperature and dry), CTD(cold temperature and dry) and ETW(elevated temperature and wet). The failure mode of the bolt jointed composite specimens are studied by test and finite element analysis. Finite element analysis reasonably predicts the failure load and mode of the joints. Reliability-based design is performed for the bolt jointed composites of radome.
김지흥(Jeeheung Kim),유홍균(Hongkyun Ryu),박영주(Young-Ju Park),이병남(Byungnam Lee) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.4
본 논문에서는 항공기 탑재에 적합한 초광대역 회전 방향 탐지 안테나를 설계 및 제작하였다. 제안된 안테나는 초광대역 주파수 범위(UHF–Ka 대역)를 수용하기 위해 저대역(UHF–L 대역)과 고대역(S–Ka 대역) 안테나로 분리하여 설계하였다. 고대역 안테나는 LPDA(Log Periodic Dipole Array) 안테나 급전 옵셋 파라볼릭 안테나를 적용하였다. 저대역 안테나의 경우, 전체 안테나 크기 증가 없이 적용하기 위해, LPDA 안테나 2소자를 고대역 안테나의 반사판 앞에 배열하였다. 제작된 안테나의 저대역과 고대역 안테나 이득은 각각 평균 8.76 ㏈i, 24.55 ㏈i로 측정되었다. 안테나의 크기는 직경 437 ㎜, 높이 358 ㎜로 제작되었다. 따라서 설계된 안테나는 항공기 탑재에 적합한 크기와 고이득 및 좁은 빔폭 특성을 가져 회전 방향 탐지 안테나로 적합함을 확인하였다. Herein, an ultrawideband spinning direction finding (DF) antenna was designed and fabricated for airborne applications. The proposed antenna is designed by dividing the low-band (UHF–L band) and high-band (S–Ka band) antennas to cover the ultrawideband frequency range (UHF–Ka band). For the high-band antenna, an LPDA antenna fed offset-parabolic-reflector antenna is applied. In the low-band antenna, two LPDA antenna elements are arrayed in front of the reflector of the high-band antenna without increasing to the full antenna size. The low- and high-band gains of the fabricated antenna were measured as 8.76 ㏈i and 24.55 ㏈i on average, respectively. The antenna was fabricated with the dimensions of 437 ㎜ in diameter and 358 ㎜ in height. Consequently, we confirmed that the designed antenna is appropriate for the spinning DF antenna in terms of the affordable size for installing on an airplane, as well as the high gain and narrow beamwidth.
Vector Fitting기법을 이용한 필터링 전도체 비발디 안테나의 등가회로 구현
이철수(Cheolsoo Lee),유홍균(Hongkyun Ryu),박범준(Beomjun Park),김인선(Inseon Kim),박주래(Joorae Park) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6
An equivalent circuit model is demonstrated of the wideband metallic Vivaldi array antenna with band notched performance using vector fitting technique (VFT). The metal post placed in the resonator for broadband impedance matching is achieved band stop function. A numerical S11 characteristic of the filtering Vivaldi antenna is calculated using CSTMWS and the rational terms are driven using ‘rational’ function of MATLAB. The results of the reflection of the equivalent circuit using ADS, the frequency response of rational terms of VFT and CST-MWS are agreed well each other.