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5G 이동통신을 위한 GaN RF 전자소자 및 집적회로 기술 동향
이종민,민병규,장우진,지홍구,조규준,강동민,Lee, J.M.,Min, B.G.,Chang, W.J.,Ji, H.G.,Cho, K.J.,Kang, D.M. 한국전자통신연구원 2021 전자통신동향분석 Vol.36 No.3
As the 5G service market is expected to grow rapidly, the development of high-power, high-efficiency power amplifiers for the 5G communication infrastructure is indispensable. Gallium nitride (GaN) is attracting great interest as a key device in power devices and integrated circuits due to its wide bandgap, high carrier concentration, high electron mobility, and high-power saturation characteristics. In this study, we investigate the technology trends of Ka-band GaN radio frequency (RF) power devices and integrated circuits for operation in the millimeter-wave band of recent 5G mobile communication services. We review the characteristics of GaN RF high electron mobility transistor (HEMT) devices to implement power amplifiers operating at frequencies around 28 GHz and compare the technology of foreign companies with the device characteristics currently developed by the Electronics and Telecommunication Research Institute (ETRI). In addition, the characteristics of Ka-band GaN monolithic microwave integrated circuit (MMIC) power amplifiers manufactured using various GaN HEMT device technologies are reviewed by comparing characteristics such as frequency band, output power, and output power density of integrated circuits. In addition, by comparing the performance of the power amplifier developed by ETRI, the current status and future direction of domestic GaN power devices and integrated circuit technology will be discussed.
Experimental Study on the Evaluation of Fatigue Life in a Double-lap Bolted Joint
J. M. Lee(이종민),N. G. Jun(전남규),K. B. Park(박기범),C. S. Seok(석창성) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
Double-lap bolted joint in bracket structure has been used in various fields including vehicle industry to connect mechanical components. There is huge risk of bolt loosening in the structure as vehicle is exposed to external factors such as static load, fatigue load, vibration or thermal shock. Cyclic load reduces clamping force formed in the structure, which leads to the instability of the joint and even serious industrial accidents. Therefore, the fatigue life of the double-lap bolted joint according to operating condition, such as cyclic load and tightening torque, has to be quantitatively evaluated to understand the progress of the loosening state and reduce the possibility of the accidents. In this study, fatigue tests were conducted for the bolted joint according to the cyclic load and tightening torque. Clamping force-cycle graph for each condition was obtained by developing a measurement technique to record the data in real time. By analyzing the clamping force-cycle graphs according to the test condition, the fatigue characteristic of the structure is evaluated. Finally, a method to select proper clamping force to prevent bolt loosening in the structure is suggested based on the evaluation of the fatigue life.