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Impact of MW, CSR, and RO Satellite Observations on the Korean Integrated Model (KIM) at KMA
Seungwoo Lee,Mee-Ja Kim,Eun-Hee Kim,Hye-Young Kim 한국기상학회 2021 한국기상학회 학술대회 논문집 Vol.2021 No.10
In this study, we investigated the impact of microwave (MW), clear sky radiance (CSR), and radio occultation (RO) data on the improvement in quality of initial analysis and the predictive performance of global numerical model at KMA. Recently, KMA has carried out a task to improve the operational data assimilation system for the performance of KIM model. Several components, such as increased resolution of variational method, update of RTTOV version, newly estimated background error covariances, effective use of radio sonde, and additional ingestion of satellite data, contributed to the improved data assimilation system. Meanwhile, satellite data were the main sources for a significant improvement in the quality of initial fields verified against ECMWF analysis data. We investigated some individual experiments in order to evaluate the relative impact of each satellite observation on the predictive performance of global model. Overall, the RO data showed much higher impact on the improved performance of KIM model than any other satellite observation data. The MW data revealed noticeable benefits to the lower level temperature at late forecast lead time, while the CSR data presented marginal impact on the predictive skills for each synoptic variable.
Seungwoo Lee(이승우),Min-Kyung Jang(장민경),Nam-Young Kim(김남영),Hye-Ji Jang(장혜지),Dong-Geun Lee(이동근),Mihyang Kim(김미향),Yuck Young Kim(김육용),Sung Gu Kim(김성구),Byung Hong Yoo(유병홍),Sang-Hyeon Lee(이상현) 한국생명과학회 2010 생명과학회지 Vol.20 No.12
In order to evaluate estrogenic compounds in brown algae, an in vitro test system for the verification of estrogenic activity was applied. Fractions from ethanol extracts of each brown alga were prepared by a systematic fractionation procedure with solvents such as H₂O, hexane, butanol and methanol. Aqueous fractions of brown algae showed the highest estrogenic activities. Estrogenic activities of 500 ㎍/㎖ aqueous fractions of Undaria pinnatifida and Laminaria japonica showed almost the same strength as that of 10?? M standard solution (17β-estradiol). Furthermore, estrogenic activities of 500 ㎍/㎖ aqueous fractions of Ecklonia stolonifera and Porphyra suborbiculate represented higher activities than that of 10?? M 17β-estradiol. These observations suggest that aqueous fractions of all these brown algae are expected to possess estrogenic compounds and could be developed as estrogenic agents for postmenopausal disorder.
Spatial Resolution and Blurring Artifacts in Digital X-ray Tomosynthesis
Kim, Daecheon,Kim, Dong Woon,Yun, Jonghee,Ha, Seungwoo,Kim, Seung Ho,Youn, Hanbean,Kim, Ho Kyung Professional Technical Group on Nuclear Science 2018 IEEE transactions on nuclear science Vol. No.
<P>Digital tomosynthesis (DTS) is an X-ray imaging technique that produces cross-sectional images with a scanning motion in narrow angular ranges. This method is promising for the inspection of internal defects in thin slab objects, such as printed circuit boards. However, this limited angular scan approach can have limited resolution in the depth direction. In addition, it can cause ghosting artifacts that originate from other planes in the reconstructed plane. In this paper, we characterized the imaging performance of a DTS method that uses the filtered backprojection for reconstruction. Various imaging parameters were examined, such as the total scan angle and the number of projections used for the reconstruction. We analyzed the signal and noise characteristics of the reconstructed images obtained for a thin tungsten wire and a thin aluminum disc. We obtained in-plane and in-depth modulation transfer functions (MTFs) from the reconstructed wire response images. From the reconstructed disc response images, we calculated the signal difference between the disc region and the adjacent background region along the depth direction, which is called the artifact spread function (ASF). A narrow angular scan enhances the in-plane MTF performance compared to that obtained from the conventional computed tomography, but it degrades the in-depth MTF performance (i.e., it decreases the depth resolution). In addition, the narrow angular scan degrades the ASF performance and causes severe out-of-plane blur artifacts. The optimal scanning angular range is, therefore, required to obtain tomographic images with high spatial resolution and less blur artifacts. The analysis method performed in this paper could be useful for this optimization.</P>
김승우(Seungwoo Kim),박기철(Kicheol Park),이기호(Kiho Lee),김경수(Kyungsoo Kim),김동권(Dongkwon Kim) 한국유체기계학회 2002 유체기계 연구개발 발표회 논문집 Vol.- No.-
A centrifugal compressor of 50HP for reverse brayton cryocooler using neon as a coolent has been developed. It has relatively low total-to-total pressure ratio but mass flow rate is very small and the woking gas, neon, has greater specific heat ratio than air. It was essential to have very high rotational speed of 100,000 RPM. The efficiency of compressor has great effects on overall system and the COP of cryocooler. To meet the dsesign requirement of the compressor efficiency and to minimized the required rotational speed, highly efficiency impeller having low specific speed was designed. To maintain the overall system efficient high, gas bearing of bump type and high speed permanent magnet synchronus motor was developed and adopted. In this paper, design and performance prediction results of the compressor impeller is presented.
Reversibly Stretchable and Tunable Terahertz Metamaterials with Wrinkled Layouts
Lee, Seungwoo,Kim, Seongnam,Kim, Teun‐,Teun,Kim, Yushin,Choi, Muhan,Lee, Seung Hoon,Kim, Ju‐,Young,Min, Bumki WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.26
<P><B>The use of wrinkling provides a generic route to stretchable metamaterials</B>, with unprecedented terahertz tunability. The wrinkled metamaterial can be stretched reversibly up to 52.5%; the structural integrity can be maintained during at least 100 stretching/relaxing cycles. Importantly, the wrinkling of meta‐atoms offers a deterministic way to achieve controlled broadening of electrical resonance.</P>