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        검색결과 11

        2.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 3차원 바람장 생성을 위한 수치 모델의 상층기상 입력 자료로 윈드프로파일러 자료의 적용 가능성과 유용성을 조사했다. 10개 지점의 윈드프로파일러 자료와 기상 예측 모델 WRF의 결과를 기상진단 모델 CALMET에 입력하여 산출한 바람장을 8개 지역에서 관측된 라디오존데 자료와 통계적으로 비교 검증하였다. WRF 바람장 모의 결과를 CALMET에 적용하여 모의한 수평 풍속에 비해 1시간 간격의 윈드프로파일러 자료를 CALMET에 적용하여 모의한 수평 풍속이 평균 제곱근 오차 1.5 m/s 내에서 관측 결과와 일치하고 특히 연안 지역에서 해풍과 같은 국지적인 바람 변화를 잘 모의하였다. 풍향의 평균 제곱근 오차는 50° ~ 70°로써 지형의 영향으로 오염된 윈드프로파일러의 풍향 오차에 기인한다. 윈드프로파일러 자료를 CALMET에 적용하면 대부분의 고도에서 상대적으로 정확한 바람을 신속하고 정확하게 모의할 수 있기 때문에 본 연구에서 제시하는 방법은 연안 지역의 기상뿐만 아니라 안전 환경감시에 유용할 것으로 기대된다.
        4,000원
        3.
        2019.09 KCI 등재 서비스 종료(열람 제한)
        In order to analyze the sensitivity of carbon dioxide flux by soil temperature in the grassplot, carbon dioxide flux and soil temperature were observed 24 times from March, 2010 to March, 2011 at nine sites in the grassplot. The average of CO2 in the grassplot is 2.2~36.7℃, the highest in August, the lowest in January, and the average of carbon dioxide flux is 12~1479 mgCO2·m-2·hr-1, and the carbon dioxide emission from the grassplot to the atmosphere was 10 times higher in summer than in winter. The temperature response coefficient estimated by the exponential function of carbon dioxide flux according to soil temperature was ranged from 0.1065 to 0.1274, and the increase tendency of CO2 flux with soil temperature was linear at 0~2 0℃and exponential at 20~40℃. The Q10 values for each of nine observation sites on the grassplot was in the range of 2.901 ~ 3.575, and the Q10 value using the total data observed in the lawn was estimated to be 3.374. In the homogeneous grassplot area, the average of Q10 values by observation point and the Q10 value by the total data were estimated similarly.
        4.
        2016.09 KCI 등재 서비스 종료(열람 제한)
        A minimum threshold for the signal to noise ratio (SNRmin) has to be set in the data processing system of wind profiler radar (WPR). The data collection rate and the accuracy of the WPR wind vector depend on the SNRmin. The WPR at Uljin is operated with an SNRmin of 1 dB which is a relatively large threshold. We found that the accuracy and the continuity of the WPR wind vector with height were directly related to the variability of the SNR and vertical gradient of the squared refractive index. We investigated a quantitative method for determining a new SNRmin for the WPR at Uljin and it was evaluated with radiosonde data. The accuracy and continuity of the wind vector from an SNR of less than 1 dB, began to decrease at an altitude of 3.5 km. Most of the SNR values were less than –3.5 dB in altitudes higher than 3.5 km. We retrieved high-accuracy wind vectors at altitudes over 3 km where measurements were deficient with an SNRmin of 1 dB.
        5.
        2016.02 KCI 등재 서비스 종료(열람 제한)
        Ground echo is radar return from stationary targets such as buildings and trees. Wind vectors from the wind profile radar in Gangneung are affected by ground echoes due to the complex mountainous terrain located to the west and the south. These ground echoes make a spurious peak close to the direct current (DC) line signal in Doppler spectra. Wind vectors polluted by ground clutters were determined from spectra of oblique beams. After eliminated the terrain echoes, the accuracy of wind vector compared with radiosonde was improved about 68.4% and its relative coefficient was increased from 0.58 to 0.97.
        6.
        2015.04 KCI 등재 서비스 종료(열람 제한)
        Spatial distribution of precipitation has been estimated based on the local gauge correction (LGC) with a fixed inverse distance weighting (IDW), which is not optimized in taking effective radius into account depending on the radar error. We developed an algorithm, improved local gauge correction (ILGC) which eliminates outlier in radar rainrate errors and optimize distance power for IDW. ILGC was statistically examined the hourly cumulated precipitation from weather for the heavy rain events. Adjusted radar rainfall from ILGC is improved to 50% compared with unadjusted radar rainfall. The accuracy of ILGC is higher to 7% than that of LGC, which resulted from a positive effect of the optimal algorithm on the adjustment of quantitative precipitation estimation from weather radar.
        7.
        2015.01 KCI 등재 서비스 종료(열람 제한)
        Wind profiler provides vertical profiles of three-dimensional wind vectors with high spatiotemporal resolution. The wind vectors is useful to analyze severe weather phenomena and to validate the various products from numerical weather prediction model. However, the wind measurements are not immune to ground clutter, bird, insect, and aircraft. Therefore, quality of wind vectors from wind profiler must be quantitatively evaluated prior to its application. In this study, wind vectors from UHF wind profiler at Ganwon Regional Meteorological Administration was quantitatively evaluated using 27 radiosonde measurements that were launched every two or three hours according to rainfall intensity during Intensive Observation Period (IOP) from June to July 2013. In comparison between two measurements, wind vectors from wind profiler was relatively underestimated. In addition, the accuracy and quality of wind vectors from wind profiler decrease with increasing beam height. The accuracy and quality of the wind vectors for rainy periods during IOP were higher than for the clear-air measurements. The moderate rainfall intensity lead to multi-peaks in Doppler spectrum. It results in overestimation of vertical air motion, whereas wind vectors from wind profilers shows good agreement with those from radiosonde measurements for light rainfall intensity.
        8.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        In this study, the variations of the carbon dioxide fluxes were investigated with soil temperatures in the grassplot and seasonal variations of carbon dioxide concentrations and fluxes were analysed. Soil temperatures, carbon dioxide concentrations and fluxes were measured on the grassplot in Pukyong National University. Field measurements were carried out 25 times from March in 2010 to March in 2011 with nine points on the grassplot. Seasonal variations of carbon dioxide concentrations and fluxes showed an inverse relation. In summer, carbon dioxide concentrations are lower and carbon dioxide fluxes are higher. In winter, carbon dioxide concentrations are higher and carbon dioxide fluxes are lower. On the grassplot, carbon dioxide emission rate increase when the soil temperature is more than 20℃ and the emission rate decrease when the soil temperatures are less than 10℃. When the accumulated rainfall for five days before measurement day is 20~100 mm, it is showed that the more rainfall, the more carbon dioxide emissions. Carbon dioxide emission rate from the grassplot to the upper atmosphere was increased or decreased by the factors such as soil temperature, growth and wither of grass and rainfall. The results of this study showed that the emission of carbon dioxide in the grassplot is dominantly controlled by seasonal factors (especially soil temperature and rainfall).
        9.
        2014.03 KCI 등재 서비스 종료(열람 제한)
        In this study, before and after sunset carbon dioxide concentration and air temperature were observed in two points of atmosphere (lower observation point of the GL + 0.1 m, the upper observation point of GL + 1.0 m) on the foreshore at located in Suncheon Bay and their variations were analyzed. Observation was performed on the foreshore on 2~4 August 2010. Instrument (VAISALA, GMP343) was set two hours before sunset and then observation was made continuously for six hours. In three days, observed carbon dioxide concentration was 375~419 ppm, and the air temperature was in the range of 28.7~32. 5℃. The average concentration of carbon dioxide was 388~399 ppm in the upper observation point and 386~396 ppm in the lower observation point. It was higher in the upper observation point and its fluctuations were similar in two observation points. Correlation coefficients between carbon dioxide concentration and air temperature in the upper observation point were in the range of –0.64~–0.88, and were calculated –0.65 to -0.90 in the lower observation point. For the carbon dioxide concentration, correlation coefficients between the upper part and the lower part were very high as 0.98 in three times. For the air temperature, correlation coefficients between the upper part and the lower part were very high as 0.97 and 0.99. In the same observation time, the slope of the linear regression function as carbon dioxide concentration in the lower observation point for the upper observation point was in the range of 0.97~1.01. Carbon dioxide concentration was slightly higher in the upper observation point. Because carbon dioxide in the lower observation point was closer on the surface of the foreshore and absorbed from atmosphere to the foreshore. In this study, it was showed that the vertical variation of carbon dioxide concentration was insignificant in the several meter scale of atmosphere on the surface of the foreshore.
        10.
        2012.06 KCI 등재 서비스 종료(열람 제한)
        This research investigated to reduce mass of heavy metals in AMD(acid mine drainage) by microbial mats formed on the channel bed. As, Cd, Cu, Fe, Mn and Zn components were monitored in water and microbial mats, at three points (AMD1, AMD2 and AMD3), in a total of six times. Average daily discharge mass of heavy metals was highest in July, Fe component contained more than 76% of total discharge mass. Discharge mass of heavy metals of AMD and heavy metal contents in microbial mats decreased with downstream at channel. Heavy metal components that average daily discharge mass is over 0.5 kg were Fe, Cu and Zn, and they were highest in July. Average removal efficiency of heavy metals in AMD was highest about 21% in Fe, this microbial mats were due to form from precipitation of Fe component in AMD by aerobic iron bacteria. Relative content for As component in microbial mats than AMD was over 16 times, this As components were due to absorb at iron oxide and iron hydroxide on the surface of microbial mats.
        11.
        2011.08 KCI 등재 서비스 종료(열람 제한)
        For this research, they were monitored CO2 flux and environmental factors (CO2 concentration, soil temperature, soil moisture, soil organic carbon, soil pH, soil Eh) in foreshore, paddy field and woods sites at the winter season (January 2009) and the summer season (September 2009). Seasonal and spatial variations for monitored data were analyzed, and linear regression functions of CO2 flux as environmental factors were estimated. CO2 fluxes averaged between surface and atmosphere monitored in foreshore and paddy field at the winter season were shown -8 mgCO2m-2hr-1 and -25 mgCO2m-2hr-1, respectively. CO2 fluxes averaged between surface and atmosphere monitored in foreshore and paddy field at the summer season were shown 47 mgCO2m-2hr-1 and 117 mgCO2m-2hr-1, respectively. Thus, CO2 was sunk from atmosphere to surface at the winter season and it was emitted from surface to atmosphere at the summer season. CO2 fluxes in woods site were emitted 145 mgCO2m-2hr-1 at the winter season and 279 mgCO2m-2hr-1 at the summer season.