• 제목/요약/키워드: retrieval bias

검색결과 57건 처리시간 0.023초

TEMPORAL VARIATIONS OF URBAN HEAT ISLAND USING LAND SURFACE TEMPERATURE DERIVED FROM MTSAT-1R

  • Hong, Ki-Ok;Suh, Myoung-Seok;Kang, Jeon-Ho;Kwak, Chong-Heum;Kim, Chan-Soo
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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    • pp.290-293
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    • 2007
  • The land surface temperature (LST) derived from the meteorological satellite can be used to investigate the urban heat island (UHI) and its temporal variations. In this study, we developed LST retrieval algorithm from MTSAT-1R by means of a statistical regression analysis from radiative transfer simulations using MODTRAN 4 for a wide range of atmospheric, satellite viewing angle (SVA) and lapse rate conditions. 535 sets of thermodynamic initial guess retrieval (TIGR) were used for the radiative transfer simulations. Sensitivity and intercomparison results showed that the algorithm, developed in this study, estimated the LST with a similar bias and root mean square errors to that of other algorithms. The magnitude, spatial extent, and seasonal and diurnal variations of the UBI of Korean peninsula were well demonstrated by the LST derived from MTSAT-1R data. In general, the temporal variations of UHI clearly depend on the weather conditions and geographic environment of urban.

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An Improved Estimation of Outgoing Longwave Radiation Based on Geostationary Satellite

  • Kim, Hyunji;Seo, Minji;Seong, Noh-hun;Lee, Kyeong-sang;Choi, Sungwon;Jin, Donghyun;Huh, Morang;Han, Kyung-Soo
    • 대한원격탐사학회지
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    • 제35권1호
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    • pp.195-201
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    • 2019
  • The Outgoing Longwave Radiation (OLR) is an important satellite-driven variable for understanding the Earth's energy budget balance. The geostationary OLR retrievals require angular and spectral integration using an empirical equation for irradiance flux-to-OLR from a regression analysis, which determines the accuracy of the narrowband satellite-based OLR. We selected homogeneous pixels which is satisfied less temporal-spatial variability of cloud, on three infrared channels (6.7, 10.8, $12.0{\mu}m$) of the first multipurpose geostationary satellite in Korea, namely the Communication, Ocean and Meteorological Satellite/Meteorological Imager (COMS/MI). Multiple regression analysis was performed to retrieve OLR with improved accuracy using selected parameters based on theoretical and physical significance. This algorithm yielded retrieval with higher accuracy than broadband-based OLR retrieval: RMSE of 10.54 to $3.81W\;m^{-2}$, and bias of -8.49 to $-0.07W\;m^{-2}$.

절박 유산의 한약 치료 효과에 대한 무작위 대조 임상시험 연구 고찰 (A Review of Randomized Controlled Trials on the Treatment Effects of Herbal Medicine for Threatened Abortion)

  • 노언지;김동철
    • 대한한방부인과학회지
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    • 제35권4호
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    • pp.57-76
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    • 2022
  • Objectives: This review is aimed to figure out the effectiveness of herbal medicine for treating threatened abortion by analyzing randomized controlled trials. Methods: We searched relevant studies using seven databases including 4 domestic databases and 3 foreign databases. Data retrieval was conducted on May 18, 2022. and the papers published from January 1, 2018 to May 18, 2022 were included. The risk of bias was assessed by using Cochrane's risk of bias tool. Results: 182 studies were searched in domestic and foreign databases, and 9 studies were finally selected. Among 9 studies, the treatment group was treated with only oral herbal medicine in 4 studies and with combined treatment of herbal medicine and western medicine in 5 studies. On the other hand, the control group was treated with only western medicine. In all 9 studies, evaluation indexes in the treatment group showed more effectiveness than those of the control group, evaluation indexes were different for each study though. Conclusions: Herbal medicine was more effective for treating threatened abortion whether using it alone or combining with western medicine compared to using western medicine alone. Additional studies which include large number are needed to confirm long-term effectiveness and safety of herbal medicine treatment.

우량계 강우를 이용한 레이더 강우의 Ground-Truth 방법 검토 (On Ground-Truth Designs of Radar Rainfall Using Rain Gauge Rainfall)

  • 유철상;김병수;김경준;최정호
    • 한국수자원학회논문집
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    • 제40권9호
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    • pp.743-754
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    • 2007
  • 본 연구에서는 레이더 강우의 ground-truth를 위해 가능한 3가지 비교방법, 즉 3가지 ground-truth설계를 이론적으로 검토하였다. 이론적인 결과는 먼저, WGR강우모형으로 모의된 3차원 강우장에 적용하여 검토하였으며, 아울러 실측자료인 관악산 레이더 자료 및 레이더 관측영역 내 건설교통부 관할 지상관측소 강우 자료에 적용하여 평가하였다. 전체적인 적용결과는 이론적인 분석내용 및 모의 강우를 이용하여 수행한 내용과 유사함을 확인하였다. 결론적으로 레이더 및 우량계 강우가 양(+)인 경우만을 비교하는 형태는 심각한 설계편의를 유발하여 레이더 강우의 ground-truth에 적절하지 못함을 확인할 수 있었다.

고고도 장기체공무인기 운영고도에서 해양 총가강수량 추정 (Estimation of Oceanic Total Precipitable Water from HALE UAV)

  • 조영준;장현성;하종철;최규용;김기훈;임은하;윤종환;이재일;성지인
    • 대기
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    • 제27권3호
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    • pp.359-370
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    • 2017
  • In this study, the oceanic Total Precipitable Water (TPW) retrieval algorithm at 16 km altitude of High Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV) is described. Empirical equation based on Wentz method (1995) that uses the 18.7 and 22.235 GHz channels is developed using the simulated brightness temperature and SeeBor training dataset. To do radiative simulation, Satellite Data Simulator Unit (SDSU) Radiative Transfer Model (RTM) is used. The data of 60% (523) and 40% (349) in the SeeBor training dataset are used to develop and validate the TPW retrieval algorithm, respectively. The range of coefficients for the TPW retrieval at the altitude of 3~18 km with 3 km interval were 153.69~199.87 (${\alpha}$), 54.330~58.468 (${\beta}$), and 84.519~93.484 (${\gamma}$). The bias and RMSE at each altitude were found to be about $-0.81kg\;m^{-2}$ and $2.17kg\;m^{-2}$, respectively. Correlation coefficients were more than 0.9. Radiosonde observation has been generally operated over land. To validate the accuracy of the oceanic TPW retrieval algorithm, observation data from the Korea Meteorological Administration (KMA) Gisang 1 research vessel about six clear sky cases representing spring, autumn, and summer season is used. Difference between retrieved and observed TPW at 16 km altitude were in the range of $0.53{\sim}1.87kg\;m^{-2}$, which is reasonable for most applications. Difference in TPW between retrieval and observation at each altitude (3~15 km) is also presented. Differences of TPW at altitudes more than 6 km were $0.3{\sim}1.9kg\;m^{-2}$. Retrieved TPW at 3 km altitude was smaller than upper level with a difference of $-0.25{\sim}0.75kg\;m^{-2}$ compared to the observed TPW.

우리나라 도심지에서의 저장열 산출에 관한 연구 (A Study on Retrieval of Storage Heat Flux in Urban Area)

  • 이다래;김홍희;이상현;이두일;홍진규;홍제우;이근민;이경상;서민지;한경수
    • 대한원격탐사학회지
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    • 제34권2_1호
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    • pp.301-306
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    • 2018
  • 도시화는 여름철 도시형 홍수, 도시 열섬 등의 문제를 야기시킨다. 이러한 현상을 해결하기 위해서는 도시 열환경 변화의 정확한 파악이 필요하다. 이는 에너지 수지를 통해 설명될 수 있지만, 도심지의 경우 일반적인 에너지 수지와 달리 건물이나 인공토지피복에 의해 저장된 열에너지인 저장열을 고려하여야 한다. 하지만 저장열은 도시 표면의 복잡한 3차원 구조와 피복의 다양성 때문에 그 산출이 어려우며, 도시마다 다른 환경으로 인해 선행연구의 저장열 산출 방법을 타 도심지에 적용시키는 데는 어려움이 존재한다. 특히 대부분의 선행연구는 국외 도시를 중심으로 이루어졌기 때문에 국내 도심지의 다양한 토지피복과 건물 특성에 적합한 저장열 산출 연구가 필요하다. 따라서 본 연구에서는 국내 도심지의 다양한 지표타입이 존재하는 지역의 자료를 이용하여 저장열의 정량적인 산출이 가능한 회귀 식 도출을 목적으로 한다. 이를 위해 순복사와 지표면 온도 자료를 독립변수로, 플럭스 타워 기반 저장열 추정치를 종속변수로 사용하여 비선형 회귀분석을 수행하였으며, 산출된 회귀계수를 각 독립변수에 적용하여 저장열 산출 회귀 식을 도출하였다. 플럭스 타워 기반 저장열 추정치의 시계열 분석 결과 본 연구에서 산출한 저장열이 주간의 high peak와 야간에서의 값의 분포와 경향을 잘 모의하고 있었고, 플럭스 타워 기반 저장열 추정치에 비해 연속적인 저장열 산출이 가능하였다. 또한 산점도 분석 결과 Root Mean Square Error (RMSE) $50.14Wm^{-2}$, bias $-0.94Wm^{-2}$로 유의한 수준의 정확도를 보였다.

복사전달모의를 통한 중적외 파장역의 민감도 분석 및 지표면온도 산출 가능성 평가 (Evaluation of Sensitivity and Retrieval Possibility of Land Surface Temperature in the Mid-infrared Wavelength through Radiative Transfer Simulation)

  • 최윤영;서명석;차동환;서두천
    • 대한원격탐사학회지
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    • 제38권6_1호
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    • pp.1423-1444
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    • 2022
  • 본 연구에서는 대기 및 지표면 인자들에 대한 중적외 파장역의 복사휘도의 민감도를 복사전달모델인 MODerate resolution atmospheric TRANsmission (MODTRAN)6을 이용하여 분석하고 이를 이용하여 야간에 중적외 파장역 만을 이용한 지표면온도 산출 가능성을 평가하였다. 이를 기반으로 야간에 대해 다양한 조건을 반영한 지표면온도 산출식을 개발하고 처방 온도 자료와 현장 관측 자료를 이용하여 개발된 지표면온도 산출식의 수준을 평가하였다. 중적외 파장역을 활용한 위성 원격탐사에 주로 영향을 미치는 대기연직구조, 이산화탄소와 오존, 지표면온도의 일 변동, 지표면 방출률 그리고 위성의 관측각에 대해 민감도 실험을 실시하였다. 이때 분리대기창 기법 활용 가능성을 평가하기 위해 중적외 파장역을 투과율을 근거로 2개의 밴드로 분리한 후 민감도를 분석한 결과 밴드와 관계없이 대기연직구조에 가장 큰 영향을 받으며 지표면 방출률, 지표면온도의 일 변동, 위성의 관측각 순으로 영향을 받았다. 주요 변인 실험 모두에서 대기의 창에 해당되는 밴드 1은 민감도가 낮은 반면 오존과 수증기 흡수가 포함된 밴드 2에서는 민감도가 높아서 분리대기창 기법을 활용하여 지표면온도 산출이 가능할 것으로 판단하였다. 중적외 2개 밴드와 다양한 변인들을 이용하여 개발된 지표면온도 산출식은 복사모의 시 입력된 기준 지표면온도와 상관계수, 편의 그리고 root mean squared error (RMSE)가 각각 0.999, 0.023K과 0.437K의 수준을 보였다. 또한 26개의 현장관측 지표면온도 자료로 검증한 결과 상관계수는 0.993, 편의는 1.875K, RMSE는 2.079K을 보였다. 본 연구의 결과는 대기 및 지표면 조건이 야간의 중적외 두 밴드에 미치는 영향이 다른 특성을 이용하여 지표면온도를 산출할 수 있음을 제시한다. 따라서 향후에는 중적외 파장역 센서를 탑재한 위성자료를 이용하여 지표면온도를 산출하고 그 수준을 평가해 볼 필요가 있다.

Aqua 위성 AMSU-A 고도별 온도자료를 이용한 열적 대류권계면 고도 산출 및 활용 (Retrieval of Thermal Tropopause Height using Temperature Profile Derived from AMSU-A of Aqua Satellite and its Application)

  • 조영준;신동빈;권태영;하종철;조천호
    • 대기
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    • 제24권4호
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    • pp.523-532
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    • 2014
  • In this study, thermal tropopause height defined from WMO (World Meteorological Organization) using temperature profile derived from Advance Microwave Sounding Unit-A (AMSU-A; hereafter named AMSU) onboard EOS (Earth Observing System) Aqua satellite is retrieved. The temperature profile of AMSU was validated by comparison with the radiosonde data observed at Osan weather station. The validation in the upper atmosphere from 500 to 100 hPa pressure level showed that correlation coefficients were in the range of 0.85~0.97 and the bias was less than 1 K with Root Mean Square Error (RMSE) of ~3 K. Thermal tropopause height was retrieved by using AMSU temperature profile. The bias and RMSE were found to be -5~ -37 hPa and 45~67 hPa, respectively. Correlation coefficients were in the range of 0.5 to 0.7. We also analyzed the change of tropopause height and temperature in middle troposphere in the extreme heavy rain event (23 October, 2003) associated with tropopause folding. As a result, the distinct descent of tropopause height and temperature decrease of ~8 K at 500 hPa altitude were observed at the hour that maximum precipitation and maximum wind speed occurred. These results were consistent with ERA (ECMWF Reanalysis)-Interim data (potential vorticity, temperature) in time and space.

만성 골반염의 한약 치료에 대한 무작위 대조 임상시험 연구 분석 (Review of Randomized Controlled Trials of Traditional Herbal Medicine for Chronic Pelvic Inflammatory Disease)

  • 노언지;안수연;김동철
    • 대한한방부인과학회지
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    • 제34권4호
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    • pp.46-61
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    • 2021
  • Objectives: The purpose of this review is to overview the studies of traditional herbal medicine for chronic pelvic inflammatory disease. Methods: We searched relevant studies using seven databases (The Journal of Korean obstetrics & gynecology, National Digital Science Library (NDSL), Research Information Sharing Service (RISS), Oriental Medicine Advanced Searching Integrated System (OASIS), Pubmed, Cochrane, Chinese National Knowledge Infrastructure (CNKI)). Data retrieval was carried out on April 5, 2021 and the papers published from January 1, 2015 to March 31, 2021 were included. The risk of bias was assessed by using Cochrane's risk of bias tool. Results: 524 studies were searched in domestic and foreign databases, and 7 studies were finally selected. In all studies, the treatment group was treated with oral traditional herbal medicine and the control group was treated with western medicine. Although the evaluation index was slightly different for each study, all studies used total efficacy rate index. In all 7 studies, the treatment group was more effective than the control group. Conclusions: Traditional herbal medicine can be an effective option in treating chronic pelvic inflammatory disease. Further high quality studies which include large number should be carried out to confirm the evidence and safety of traditional herbal medicine treatment.

기공 운동 치료가 고혈압에 미치는 영향: 체계적 문헌 고찰 (Qigong Exercise Therapy for Hypertension: A Systematic Review)

  • 안재규;이상현;김현태;박선영;허인;정민정;황의형;장인수
    • 척추신경추나의학회지
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    • 제15권2호
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    • pp.9-18
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    • 2020
  • Objectives This study verified the clinical effectiveness of Qigong exercise therapy for individuals with hypertension. Methods Ten electronic databases were used for information retrieval. Only randomized controlled trials (RCTs) using Qigong exercise therapy as a treatment for hypertension were included in this study. Cochrane risk of bias tool was used to assess the methodological quality of each RCT. Results After a thorough review, six RCTs were deemed eligible. These studies were divided into two groups: Qigong vs. no intervention and Qigong plus anti-hypertensive drug vs. anti-hypertensive drug alone. Among the six RCTs, four studies were Qigong vs. no intervention, and two studies were Qigong plus anti-hypertensive drug vs. anti-hypertensive drug alone. The meta-analysis demonstrated that adding Qigong exercise to anti-hypertensive drug treatment lowers diastolic blood pressure more than the anti-hypertensive drug alone. Conclusions Although Qigong exercise is not widely used in the Korean medical field, the results of this study demonstrated the necessity of exercise while controlling hypertension. However, the number of included studies was small, with their high risk of bias. In conclusion, although it is difficult to determine whether Qigong exercise lowers blood pressure in hypertensive patients, exercise including Qigong must be parallel with the intake of anti-hypertensive drugs.