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RISS 인기검색어
- 검색키워드
- 저자 : 이윤곤 (검색결과 158 건)
- 무료
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A Derivation of Aerosol Optical Depth Estimates from Direct Normal Irradiance Measurements
이윤곤,김창기 한국신·재생에너지학회 2024 신재생에너지 Vol.20 No.1
This study introduces a method for estimating Aerosol Optical Depth (AOD) using Broadband Aerosol Optical Depth(BAOD) derived from direct normal irradiance and meteorological factors observed between 2016 and 2017. Through correlationanalyses between BAOD and atmospheric components such as Rayleigh scattering, water vapor, and tropospheric nitrogen dioxide,significant relationships were identified, enabling accurate AOD estimation. The methodology demonstrated high correlation coefficientsand low Root Mean Square Errors (RMSE) compared to actual AOD500 measurements, indicating that the attenuation effects of watervapor and the direct impact of tropospheric nitrogen dioxide concentration are crucial for precise aerosol optical depth estimation. Theapplication of BAOD for estimating AOD500 across various time scales—hourly, daily, and monthly—showed the approach’srobustness in understanding aerosol distributions and their optical properties, with a high coefficient of determination (0.96) formonthly average AOD500 estimates. This study simplifies the aerosol monitoring process and enhances the accuracy and reliability ofAOD estimations, offering valuable insights into aerosol research and its implications for climate modeling and air quality assessment. The findings underscore the viability of using BAOD as a surrogate for direct AOD500 measurements, presenting a promising avenuefor more accessible and accurate aerosol monitoring practices, crucial for improving our understanding of aerosol dynamics and theirenvironmental impacts.
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이윤곤,김준,조히구,최병철,김지영,정성래,박일수 한국기상학회 2008 Asia-Pacific Journal of Atmospheric Sciences Vol.44 No.4
New ultraviolet (UV) index forecast model was developed by using radiative transfer model and improved multiple linear regression for total ozone prediction using new predictors based on extensive investigation on their correlations with total ozone, and new modification factor for clouds, aerosols and surface reflectance. For clear sky case, root mean square error (RMSE) of newly-forecasted UV index with respect to observations is reduced by 16.0% with using improved forecast of total ozone,by 25.2% with cloud modification factor (CMF) applied, and by 32.7% with CMF and aerosol modification factor (AMF) compared to the existing forecast at Korea Meteorological Administration (KMA), which utilized the state-of-the-art UV radiative transfer model together with multiple regression model. The percentage improvement is estimated to be 16.0% through the application of new total ozone forecast, 9.2% with the new CMF, and 7.5% with the new AMF. The accuracy of UV index forecast for cloudy skies is subjected to the errors of next day’s cloud forecast for the modification, but the forecast of UV index for clear sky conditions shows significant improvement.
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Effects of the Shape of the Base of Support and Dual Task Execution on Postural Control
이윤곤,신성훈 대한운동학회 2019 아시아 운동학 학술지 Vol.21 No.1
[OBJECTIVES] The current investigation examined the effects of a dual task execution, based on the shape of the base of support (BOS) and the task characteristics (i.e., dual or non-dual tasks), on the posture control, and how the interaction effects appear according to the combination of the two variables. [METHODS] A total of 22 young adults (11 males and 11 females) participated in the study. The participants were instructed to stand quietly based on the shape of their BOS (normal stance, semi-tandem, or tandem) on two left and right force plates. For the dual tasks, an inverse calculation in which the subjects quietly stated to the examiner three-digit numbers (between 300 and 900), after subtracting them by 7, was conducted. A two-way repeated measures ANOVA with two within factors was used. The dependent variables were set as the linear parameters (mean velocity (MV), RMS, and 95% ellipse sway area (CEA)), power frequency parameters (95% power frequency density (F95) and mean frequency (MF)), and complexity parameters (sample entropy (SampEn) and fractal dimension (FD)) of the center of pressure (COP) time series at each anteroposterior (AP) and mediolateral (ML) direction. [RESULTS] For the linear parameters, RMS_AP and CEA had an interaction effect on the shape of the BOS and the presence of dual tasks (p<.05). For the frequency parameters, F95_AP and MF_AP had an interaction effect on the shape of the BOS and the presence or absence of dual tasks (p<.05). For the nonlinear parameters, SampEn_AP and FD_AP had an interaction effect between the shape of the BOS and the task characteristics (p<.01). [CONCLUSIONS] Postural control during the intervention of a cognitive task is complicated based on the characteristics and difficulty of the task. The reduced movement of linear variables and the increased complexity and frequency variables when under unstable postural control (i.e., tandem standing) while simultaneously conducting dual tasks reflect the active and efficient stabilization strategies of young adults.
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이윤곤,김재민,정연진,조희구,김준,구자호 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.2
We estimated the Korea Shortwave Radiation Budget (KSRB) providing new insights into the Korea climate system. Monthly averaged clear-sky, overcast-sky, and all-sky flux measurements with cloud amounts from 2000 to 2015 were used to assess the impacts of cloud on the KSRB. A deterministic model for shortwave radiation transfer was utilized with climatological data to compute the monthly mean of KSRB at the surface, in the atmosphere and at the top-of-atmosphere (TOA). For 10 Korean stations ranging from 33.5°N to 37.7°N, the daily mean of incoming solar flux at TOA is 345.2 Wm−2. 45.5% of that is transmitted to the surface, 25.0% is absorbed in the atmosphere and 29.5% is reflected directly back to space by the cloud, atmosphere and ground surface under all-sky conditions. Under clear- and overcast-sky conditions, 63.2% and 24.9% are transmitted to the surface, 17.8% and 37.1% are absorbed in the atmosphere, whereas 19.0% and 38.0% are reflected to space, respectively, showing a remarkably invariant value with respect to locations. Clouds in all- (or overcast-) sky atmosphere diminish surface solar irradiances (SSI) from 218.1Wm−2 to 156.9 Wm−2 (or 85.8Wm−2) and enhance atmospheric absorptions (AA) from 61.5Wm−2 to 86.3Wm−2 (or 128.2 Wm−2). Clouds also enhance the reflected irradiances (RI) at the TOA from 65.6 Wm−2 to 102.0 Wm−2 (or 131.2 Wm−2) for all- (or overcast-) skies. As a result, the all- (or overcast-) sky shortwave (SW) cloud forcing (CF) is −61.2Wm−2 (or −132.3Wm−2) at the surface, AA is 24.8Wm−2 (or 66.7Wm−2) in the atmosphere and RI is 36.4 Wm−2 (or 65.6 Wm−2) at the TOA, respectively. Consequently, it is found that the values for SW-CF at the surface is 1.7 times and 2.0 times greater than that at the TOA in the KSRB under all- and overcast-sky conditions, respectively. We have also compared the KSRB with the global shortwave radiation budget (GSRB) and discussed on the shortwave radiation budget.
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다섯 종류의 빛간섭단층촬영기로 측정한 망막신경섬유층 두께 비교
이윤곤,황영훈 대한안과학회 2018 대한안과학회지 Vol.59 No.3
Purpose: To compare circumpapillary retinal nerve fiber layer (RNFL) thicknesses as measured using five different optical coherence tomography (OCT) devices. Methods: RNFL thickness was measured in 32 healthy eyes of 32 subjects using a Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA, USA), Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany), Topcon DRI OCT (Topcon, Tokyo, Japan), RS-3000 Advance OCT (NIDEK, Aichi, Japan), and RTVue-100 (Optovue, Fremont, CA, USA). Global and quadrant (superior, nasal, inferior, and temporal) RNFL thicknesses were compared using repeated measures analysis of variance, and the agreement among devices was determined using Bland-Altman analyses. Results: The global RNFL thickness was greatest when measured using the Topcon DRI OCT, with a mean value of 107.5 μm. The mean global RNFL thicknesses measured using the RTVue-100, RS-3000 Advance OCT, and Spectralis OCT were 104.9 ± 8.4, 104.4 ± 9.4, 102.5 ± 8.9 μm, respectively. The Cirrus HD-OCT presented the thinnest RNFL measurement, with a mean value of 97.7 ± 8.7 μm (p < 0.01). A similar pattern was found for the quadrant RNFL thicknesses (p < 0.01). Differences in the global RNFL thicknesses among the devices ranged from 0.5 to 9.9 μm. The limits of agreement of the global RNFL thicknesses evaluated by Bland-Altman analyses ranged from 6.8 to 19.6 μm. Conclusions: RNFL thicknesses measured using five different OCT devices were not interchangeable and there was a wide limit of agreement. When interpreting RNFL thickness values determined by different devices, caution is advised. 목적: 다섯 종류의 빛간섭단층촬영기를 이용하여 측정한 시신경유두주위 망막신경섬유층 두께를 비교하고자 한다. 대상과 방법: 정상인 32명의 32안을 대상으로 Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA, USA), Spectralis OCT (Heidelberg engineering, Heidelberg, Germany), Topcon DRI OCT (Topcon Inc., Tokyo, Japan), RS-3000 Advance OCT (NIDEK, Aichi, Japan), RTVue-100 (Optovue Inc., Fremont, CA, USA)을 이용하여 시신경유두주위 전체 평균 및 사분면(위쪽, 코쪽, 아래쪽, 귀쪽) 망막신경섬유층 두께를 측정하였다. 각 장비로 측정한 망막신경섬유층 두께를 반복측정분산분석으로 비교하고, Bland-Altman 분석을 통해 일치도를 분석하였다. 결과: 전체 평균 망막신경섬유층 두께는 Topcon DRI OCT로 측정한 값이 평균 107.5 ± 9.0 μm로 가장 컸고, RTVue-100으로 측정한 값이 104.9 ± 8.4 μm, RS-3000 Advance OCT로 측정한 값이 104.4 ± 9.4 μm, Spectralis OCT로 측정한 값이 102.5 ± 8.9 μm였고, Cirrus HD-OCT로 측정한 값이 97.7 ± 8.7 μm로 가장 작았다(p<0.01). 사분면 망막신경섬유층 두께도 전체 평균 두께와 비슷한 양상을 보였다(p<0.01). 검사 장비 간 전체 평균 망막신경섬유층 두께 값의 차이는 0.5에서 9.9 μm였고, Bland-Altman 분석을 통해 산출한 장비 간 전체 망막신경섬유층 두께 일치도 범위(limit of agreement)는 6.8에서 19.6 μm로 나타났다. 결론: 다섯 종류의 빛간섭단층촬영 장비로 측정한 시신경유두주위 망막신경섬유층 두께는 서로 다른 값을 보였고 일치도 범위도 넓었다. 따라서 서로 다른 장비로 측정한 망막신경섬유층 두께 값을 분석할 때 주의해야 할 것이다.
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