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방신원,홍성부,이유빈,신현철,박병현,박재상 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.1
The present study using active vibration control system (AVCS) attempts to actively reduce the airframe vibration responses of a lift-offset compound helicopter at 250 knots. An 11% scaled airframe structure of the Sikorsky X2 Technology Demonstrator (TD) is used for the AVCS test and simulation and this small-scale airframe model is designed and manufactured based on the one-dimensional (1D) stick structure. The present AVCS comprises two force generators for producing vibration cancellation forces, two accelerometers to measure 4P vertical vibration responses at the pilot and copilot seats, and the filtered-x least mean square (Fx-LMS) algorithm as a closed-loop feedback controller. MATLAB Simulink is used to construct the AVCS framework for both tests and simulations. MSC.NASTRAN is applied to the dynamic design of a small-scale airframe structure and to predict of its airframe vibration responses in a simulation study. The dSPACE MicrolabBox equipment is used for the AVCS test. When the AVCS is applied to the present X2TD scaled airframe model, the 4P vertical vibration responses in the test are reduced by 68.57% and 60.24% compared to the baseline without AVCS at the pilot and copilot seats, respectively, whereas they are reduced by 70.89% and 64.11%, respectively, in the simulation. Finally, the vertical vibration reduction rates between the AVCS test and simulation are similar, and it is investigated that the vibration reduction performance is good in both the AVCS test and simulation.
황일웅 ( Hwang Il Ung ),이희경 ( Lee Hee Kyeong ),서미영 ( Seo Mi Young ),김재표 ( Kim Jae Pyo ),서유빈 ( Seo Yu Bin ),방연주 ( Bang Yeon Ju ) 국군의무사령부 2010 대한군진의학학술지 Vol.41 No.1
Objective: Carriage rate of Neisseria Meningitidis is known to be very high in the group of university students and army population although the general carriage rate is about 10%. 60∼ 80% of carriage rate was reported in the army population. To gain current information about the nasopharyngeal carriage of Neisseria meningitidis, this study was carried out. Method: 391 recruits of Korean army were swabbed two times. 1st swab was taken on the day of beginning of the army training and 2nd was done 5 weeks later. Results: Overall carriage rate was 17.6%(69) at first swabs and raised to 21.7%(85) at the second. Of 69 isolates from 1st swabs, 4 serogroups including B, C, W135, E29 were identified and 39.1%(278) were done as non-groupable. Results of serogrouping 85 isolates from the 2nd swabs were same with the 1st examination. B, C, W135, E29, non-groupable were identified. Serogroup B account for 31%(22) of 1st isolates and 60%(51) of 2nd isolates. 17 positive results converted into negative at 2nd swab. Conclusion: The carriage rate of the army recruits was higher than normal population but didn't go up so high as reported. Only 4 goups which are likely to causes disease were identified. Duration of carriage should be evaluated in the following study with longer follow up.