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Which organ decides the frequency of the sound of the cicada Meimuna mongolica?
Sooyoung Park,Eunho Oh,Jiwon Han,Kisang Yoon 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.10
쓰름매미의 진동막와 복부 중 어떤 기관이 유인음의 주파수를 결정하는지 확인하였다. 쓰름매미는 유인음 발생시 복부의 모양을 변화시켜 주파수를 변조하는 것으로 관찰되었다. 안동하회마을에 Songmeter를 설치하여 24시간동안 녹음하여 우는 시간을 분석하였다. 양쪽 진동막에서 나온 비명음을 프로브마이크로폰으로 녹음하였다. 비명음 발생시 진동막의 진동을 초고속카메라로 촬영(20,000 fps)하여 평균진동수±불확도를 분석하였다. 연구결과, 쓰름매미는 일출시각이 05:39이었던 날에 05:13부터 울기 시작하여, 일몰시각이 19:23 이후인 19:55까지 울어, 말매미·애매미·참매미와의 경쟁에서 가장 긴 시간동안 울었다. 유인음의 FFT 결과, 중심주파수는 약 6,000Hz인 고주파임을 알 수 있었다. 두 진동막은 비동시적으로 진동하였는데, 진동 주기는 5.45ms이며, 지속시간은 4.75ms으로 양쪽진동막 소리 사이 공백이 0.7ms로 중첩은 없었다. 2,061Hz의 진동은 계속 유지되고 중간에 11,111Hz의 고주파가 합성되었다. 진동막은 3가지 모드로 진동하였고, 1st 모드의 평균진동수±불확도는 1,904±78Hz, 2nd 1,644±49Hz, 3rd 1,019±39Hz로, 불확도 99% 신뢰수준에서 세 가지 모드 모두에서 양쪽 진동막의 진동수는 다르다고 할 수 없으며 또한, 모드별로 같다고 할 수 없는 것으로 나타났다. 결론적으로, 복부 공명 효과가 배제된 진동막의 진동수 범위는 2,000 Hz 미만임에도 유인음과 비명음에서 모두 6,000 Hz 이상의 소리가 관찰되는 것으로 보아 진동막은 비교적 낮은 주파수의 소리 발생하지만 복부의 부피와 모양을 변화시켜 높은 주파수의 소리를 발생하는 것으로 판단된다.
Impact of COVID-19 Pandemic on Biomedical Publications and Their Citation Frequency
Park Sooyoung,Lim Hyun Jeong,Park Jaero,Choe Yeon Hyeon 대한의학회 2022 Journal of Korean medical science Vol.37 No.40
Background: The coronavirus disease 2019 (COVID-19) pandemic has resulted in enormous related publications. However, the citation frequency of these documents and their influence on the journal impact factor (JIF) are not well examined. We aimed to evaluate the impact of COVID-19 on biomedical research publications and their citation frequency. Methods: We searched publications on biomedical research in the Web of Science using the search terms “COVID-19,” “SARS-Cov-2,” “2019 corona*,” “corona virus disease 2019,” “coronavirus disease 2019,” “novel coronavirus infection” and “2019-ncov.” The top 200 journals were defined as those with a higher number of COVID-19 publications than other journals in 2020. The COVID-19 impact ratio was calculated as the ratio of the average number of citations per item in 2021 to the JIF for 2020. Results: The average number of citations for the top 200 journals in 2021, per item published in 2020, was 25.7 (range, 0–270). The average COVID-19 impact ratio was 3.84 (range, 0.26–16.58) for 197 journals that recorded the JIF for 2020. The average JIF ratio for the top 197 journals including the JIFs for 2020 and 2021 was 1.77 (range, 0.68–8.89). The COVID-19 impact ratio significantly correlated with the JIF ratio (r = 0.403, P = 0.010). Twenty-five Korean journals with a COVID-19 impact ratio > 1.5 demonstrated a higher JIF ratio (1.31 ± 0.39 vs. 1.01 ± 0.18, P < 0.001) than 33 Korean journals with a lower COVID-19 impact ratio. Conclusion: COVID-19 pandemic infection has significantly impacted the trends in biomedical research and the citation of related publications.
Fire Resistance of the Korean Asymmetric Slim Floor Beam Depending on Load Ratio
Park, Sooyoung,Kim, Hyungjun,Kim, Heungyoul,Hong, Kappyo Architectural Institute of Japan 2011 JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEE Vol.10 No.2
<P>In Korea recently, interest is increasing in slim floor systems that have superior structural performance and fire resistance. This paper contains the results of tests to confirm the fire resistance behavior of the composite asymmetric slim floor beam. The fire resistance behavior was analyzed using the finite element program ANSYS and the finite element models were validated against the test results. The validated thermal and structural models were used to predict the fire resistance of the Korean asymmetric floor beam and the average temperature of the steel bottom flange depending on load ratio changes. As a result, the 346ASB and the 350ASB were found to have 60 minutes of fire resistance when their load ratios were under 0.47 and 0.48 respectively without additional fire protection. Also, the authors have set the average temperature of the bottom flange, which has a direct impact on the ASB system, as a limiting temperature that enables gauging of its fire resistance as a table according to the load ratio, and presented the limiting temperature as a regression equation according to the fire resistance time.</P>