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Highly Reliable Amorphous In-Ga-Zn-O Thin-Film Transistors Through the Addition of Nitrogen Doping
Park, Kyung,Kim, Jong Heon,Sung, Taehoon,Park, Hyun-Woo,Baeck, Ju-Heyuck,Bae, Jonguk,Park, Kwon-Shik,Yoon, Sooyoung,Kang, Inbyeong,Chung, Kwun-Bum,Kim, Hyun-Suk,Kwon, Jang-Yeon Institute of Electrical and Electronics Engineers 2019 IEEE transactions on electron devices Vol.66 No.1
<P>The electrical properties and the device reliability under positive/negative bias stress with/without illumination regarding amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) are evaluated as a function of the nitrogen partial pressure in the sputter deposition. Interestingly, it is easy to control the carrier concentration through the incorporation of nitrogen into IGZO, whereby the device performance is changed. In addition, when nitrogen is introduced during the conventional IGZO deposition, the device reliability of N-doped IGZO TFTs is considerably improved compared to that of undoped-IGZO TFTs due to the reduced amount of defects. It is also interesting that such an improvement of the device reliability regarding IGZO is easily obtainable through the simple addition of nitrogen to the conventional deposition process. It is, therefore, strongly believed that this simple nitrogen-doping process for IGZO is very effective regarding the achievement of highly durable devices, and it can be immediately applied to the current mass production of the high-performance displays for which the oxide semiconductor is used.</P>
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.
Total synthesis of giffonin H by fluoride-catalyzed macrocyclization
Park, Sooyoung,Kim, Seok-Ho,Jeong, Jin-Hyun,Shin, Dongyun The Royal Society of Chemistry 2019 ORGANIC CHEMISTRY FRONTIERS Vol.6 No.5
<P>The first total synthesis of giffonin H, a highly strained 15-membered macrocyclic diaryl ether, has been achieved in eight linear steps with 10% overall yield. Key steps include Ullmann cross coupling, (<I>Z</I>)-selective Julia-Kocienski olefination, and fluoride-mediated macrocyclization of TMS-alkyne and aldehyde. In particular, the strategy used for macrocyclization is an unprecedented and unique synthetic approach for cyclic diarylheptanoids. The fluoride-mediated macrocyclization strategy should be applicable to the synthesis of giffonin congeners under mild reaction conditions without affecting the integrity of subtle diene moieties.</P>
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>
Park Byunggeon,Park Jongmin,Lim Jae-Kwang,Shin Kyung Min,Lee Jaehee,Seo Hyewon,Lee Yong Hoon,Heo Jun,Lee Won Kee,Kim Jin Young,Kim Ki Beom,Moon Sungjun,Choi Sooyoung 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.11
Objective: Lung segmentation using volumetric quantitative computed tomography (CT) analysis may help predict outcomes of patients with coronavirus disease (COVID-19). The aim of this study was to investigate the relationship between CT volumetric quantitative analysis and prognosis in patients with COVID-19. Materials and Methods: CT images from patients diagnosed with COVID-19 from February 18 to April 15, 2020 were retrospectively analyzed. CT with a negative finding, failure of quantitative analysis, or poor image quality was excluded. CT volumetric quantitative analysis was performed by automated volumetric methods. Patients were stratified into two risk groups according to CURB-65: mild (score of 0–1) and severe (2–5) pneumonia. Outcomes were evaluated according to the critical event-free survival (CEFS). The critical events were defined as mechanical ventilator care, ICU admission, or death. Multivariable Cox proportional hazards analyses were used to evaluate the relationship between the variables and prognosis. Results: Eighty-two patients (mean age, 63.1 ± 14.5 years; 42 females) were included. In the total cohort, male sex (hazard ratio [HR], 9.264; 95% confidence interval [CI], 2.021–42.457; p = 0.004), C-reactive protein (CRP) (HR, 1.080 per mg/dL; 95% CI, 1.010–1.156; p = 0.025), and COVID-affected lung proportion (CALP) (HR, 1.067 per percentage; 95% CI, 1.033– 1.101; p < 0.001) were significantly associated with CEFS. CRP (HR, 1.164 per mg/dL; 95% CI, 1.006–1.347; p = 0.041) was independently associated with CEFS in the mild pneumonia group (n = 54). Normally aerated lung proportion (NALP) (HR, 0.872 per percentage; 95% CI, 0.794–0.957; p = 0.004) and NALP volume (NALPV) (HR, 1.002 per mL; 95% CI, 1.000–1.004; p = 0.019) were associated with a lower risk of critical events in the severe pneumonia group (n = 28). Conclusion: CRP in the mild pneumonia group; NALP and NALPV in the severe pneumonia group; and sex, CRP, and CALP in the total cohort were independently associated with CEFS in patients with COVID-19.