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기상조절(인공강우와 안개저감)의 경제적 가치 추정 연구
이철규(Chulkyu Lee),장기호(Ki-Ho Chang),차주완(Joo-Wan Cha),정재원(Jae-Won Jung),정진임(Jin-Yim Jeong),양하영(Ha-Young Yang),서성규(Sung-Kyu Seo),배진영(Jin-Young Bae),강선영(Sun-Young Kang),최영진(Young-Jean Choi),조하만(Ha-man Cho) 한국기상학회 2010 대기 Vol.20 No.2
We estimate the economic benefit of weather modification (precipitation enhancement and fog dissipation) by assuming its operation for the considered regions. Based on the statistical data, the economic benefit of the virtually operational precipitation enhancement experiments for the Andong and Imha basins, where the natural precipitation is relatively lack in South Korea, is calculated 348 for the water resources, 22,458 for forest fire prevention, and 28,458 million won/year for the drought relief. The benefit of the fog dissipation operation for the Incheon International Airport is estimated 7,365 million won/year for the flight delay due to fog. The calculated ratio of benefit to cost for precipitation enhancement operation for the basins is 14.07, which is comparable to that conducted in other countries.
Cha, Hyojung,Park, Jong Won,Chung, Dae Sung,An, Tae Kyu,Kim, Yun-Hi,Kwon, Soon-Ki,Park, Chan Eon The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.30
<P>A conjugated polymer donor material, poly(3,4′′′-di(decylthiophenyl)quaterthiophene) (PDTQT), featuring decylthiophenyl side chains on the polymer backbone, was introduced to reduce the crystallinity of poly(quaterthiophene) (PQT-C12) layers in organic photovoltaic cells. The resulting PDTQT:PC<SUB>71</SUB>BM blend active layer formed a well-interpenetrated nanoscale morphology that increased the power conversion efficiency (PCE) relative to devices based on highly crystalline PQT-C12. Bulk heterojunction solar cells fabricated using the PDTQT:PC<SUB>71</SUB>BM blend thin films yielded the best photovoltaic performances with a high short-circuit current density of 9.8 mA cm<SUP>−2</SUP>, a high open-circuit voltage of 0.91 V, a fill factor of 0.36, and a high PCE of 3.2% under AM 1.5G illumination with an intensity of 100 mW cm<SUP>−2</SUP>. Decylthiophenyl side chain substitution appeared to be an effective strategy for obtaining high organic photovoltaic cell device performances.</P> <P>Graphic Abstract</P><P>A conjugated polymer donor material, poly(3,4′′′-di(decylthiophenyl)quaterthiophene) (PDTQT), featuring decylthiophenyl side chains on the polymer backbone, was introduced to reduce the crystallinity of poly(quaterthiophene) (PQT-C12) layers in organic photovoltaic cells. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm32354k'> </P>
Cha, Hyung Koo,Lee, Ki Won 호남수학회 2000 한국수학학술지 Vol.17 No.1
In this note we characterize hyponormality for Toeplitz pairs one of whose coordinates is the unilateral shift by difference of analytic and co-analytic degrees of a trigonometric polynomial φ which is a symbol of Toeplitz operator. We prove the followings : Let φ be a trigonometric polynomial of the form φ(θ) ∑_κ^Ν=-m^(ακe)^(iκθ) (m $lt; Ν), and f be an analytic part of φ. Assume and |α_m|=|αN|≠0 and det(α_(m-k) α_m) = 0 for all κ = 1, 2, … , Ν - 1. Then ( αN-k αN) (i) In case N - m, = 1 : (U, Tφ) is hyponormal if and only if [Τ _φ^*,Τ _φ] = U^* ◎ U ◎ (ii) In case N - m = 2 : (U, Tφ) is hyponormal if and only if a matrix (a_(i+1)a_(j+1) is non-negative (i, j = 1, 2, …, N - 1).
A Mobile Object Tracking Scheme by Wired/wireless Integrated Street Lights with RFID
Cha, Mang Kyu,Kim, Jung Ok,Lee, Won Hee,Yu, Ki Yun 대한공간정보학회 2016 대한공간정보학회지 Vol.24 No.2
Since a sophisticated location determination technology (LDT) is necessary for accurate positioning in urban area environments, numerous studies related to the LDT using the RFID (Radio Frequency IDentification) technology have been implemented for real‐time positioning and data transferring. However, there are still lots of unsolved questions especially regarding what to use as base stations and what are corresponding results under the intrinsic complexity of alignment and configuration of components used for the RFID positioning. This study proposes the street light fixtures as base stations where the RFID receivers will be embedded for the mobile tracking scheme. As street light fixtures are usually installed at a certain distance interval, they can be used as base stations for the RFID receiver installation. Using the principle of the single row triangle network, the RFID receiver organization is determined based on the experiments such as recognition distance measurement and tag position accuracy estimation at inside and outside of the single row triangle network. The results verify that the mobile tracking scheme which uses RFID-embedded street light fixtures, suggested and configured in this study, is effective for the real-time outdoor positioning.
Methods of measuring the vibrations of a gun tube under impulse loads
Won-yeong Choi,유승열,노명규,Ki-up Cha,Chang-ki Cho,Sung-soo Kim 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.12
In many respects, accelerometers are convenient for measuring the lateral vibrations of a gun tube under impulse loads. Reliable measurements by accelerometers must overcome two issues: exceedingly large acceleration at high frequencies due to stress waves, and the elimination of drifts accumulating through the integration of acceleration signals. In this paper, we use a mechanical filter that reduces the effect of stress waves. Also, we propose a new double integration algorithm based on multi-resolution wavelet decomposition. Using a test-rig, we measure the vibration characteristics of commercially-available damping materials. Based on the test results, we design a mechanical filter and experimentally verify the performance of the filter. The proposed double integration algorithm is shown to be as effective as other existing algorithms without arbitrary selection of parameters.
Patterns of care and treatment outcomes for primary thyroid lymphoma: a single institution study
Cha, Hyejung,Kim, Jun Won,Suh, Chang-Ok,Kim, Jin Seok,Cheong, June-Won,Lee, Jeongshim,Keum, Ki Chang,Lee, Chang Geol,Cho, Jaeho The Korean Society for Radiation Oncology 2013 Radiation Oncology Journal Vol.31 No.4
Purpose: The aim of this study was to analyze the patterns of care and treatment outcomes in patients with primary thyroid lymphoma (PTL) in a single institution. Materials and Methods: Medical records of 29 patients with PTL treated between April 1994 and February 2012 were retrospectively reviewed. Diagnosis was confirmed by biopsy (n = 17) or thyroidectomy (n = 12). Treatment modality and outcome were analyzed according to lymphoma grade. Results: The median follow-up was 43.2 months (range, 3.8 to 220.8 months). The median age at diagnosis was 57 years (range, 21 to 83 years) and 24 (82.8%) patients were female. Twenty-five (86.2%) patients had PTL with stage IEA and IIEA. There were 8 (27.6%) patients with mucosa-associated lymphoid tissue (MALT) lymphoma and the remaining patients had high-grade lymphoma. Patients were treated with surgery (n = 2), chemotherapy (n = 7), radiotherapy (n = 3) alone, or a combination of these methods (n = 17). Treatment modalities evolved over time and a combination of modalities was preferred, especially for the treatment of high-grade lymphoma in recent years. There was no death or relapse among MALT lymphoma patients. Among high-grade lymphoma patients, 5-year overall survival (OS) and 5-year progression-free survival (PFS) were 75.6% and 73.9%, respectively. Complete remission after initial treatment was the only significant prognostic factor for OS (p = 0.037) and PFS (p = 0.003). Conclusion: Patients with PTL showed a favorable outcome, especially with MALT lymphoma. Radiotherapy alone for MALT lymphoma and chemotherapy followed by radiotherapy for high-grade lymphoma can be effective treatment options for PTL.