• Title/Summary/Keyword: Global Solar Irradiance

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A Study on the Temperature Reduction Effect of Street Green Area (도로변 가로녹지 유형이 기상에 미치는 영향)

  • Kim, Jeong-Ho;Choi, Won-Jun;Yoon, Yong-Han
    • Journal of Environmental Science International
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    • v.26 no.12
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    • pp.1363-1374
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    • 2017
  • Global climate change caused by industrialization has caused abnormal weather conditions such as urban temperatures and tropical nights, urban heat waves, heat waves, and heavy rains. Therefore, the study tried to analyze climate conditions and weather conditions in the streets and analyze climate factors and meteorological factors that lead to inconvenience to citizens. In the case of trees, the overall temperature, surface temperature, solar irradiance, and net radiation were measured low, and the temperature was lower in the Pedestrian road than in roads. The dry bulb temperature, the black bulb temperature, and the wet bulb temperature for the thermal evaluation showed the same tendency. In the case of thermal evaluation, there was a similar tendency to temperature in WBGT, MRT, and UTCI, and varied differences between types. Although the correlation between the meteorological environment and the thermal environment showed a statistically significant significance, the difference between the measured items was not significant. The study found that the trees were generally pleasant to weather and thermal climate in the form of trees, and the differences were mostly documented.

Performance of Photovoltaic Module according to Non-Uniform Azimuth (비동일한 방위각에 의한 PV모듈의 발전성능)

  • Kim, Hyun-Il;Park, Kyung-Eun;Lee, Ki-Ok;Kang, Gi-Hwan;Yu, Gwon-Jong;Suh, Sung-Jik
    • 한국태양에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.303-308
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    • 2009
  • In 2008, the global photovoltaic(PV) market reached 5.6GW and the cumulative PV power installed totalled almost 15GW compared to 9GW in 2007. Due to a favourable feed-in-tariff, Korea emerged in 2008 as the 4th largest PV market worldwide. PV power installation rose 495.5 percent to 268MW in 2008 compare to 45MW in 2007. However many PV systems are not installed in suitable part which is concerned about geometrical factor. It is generally recognized that the actual output of PV system in field is a function of orientation, tilt angle, irradiance, temperature, soiling and various system-related losses. Thus this paper shows that a experimental result of PV modules(A group) with uniform azimuth angle and PV modules(B group) with non-uniform azimuth angle. As a result, the electrical output of B group is decreased 48.8% as compared with electrical output of A group.

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Preliminary Experiment of the Change of Insolation under Solar Panel Mimic Shading Net (영농형 태양광 하부의 일사량 변화 분석을 위한 모의 차광 관측 실험)

  • Yoon, Changyong;Choi, Seonwoong;An, Kyu-Nam;Ryu, Jae-Hyun;Jeong, Hoejeong;Cho, Jaeil
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.21 no.4
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    • pp.358-365
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    • 2019
  • An agrivoltaic systems (AVS) is mixed systems associating photovoltaic panels (PVPs) and crop cultivation at the same time on the given land area. It is receiving attention to improve rural economy. However, it is likely that, the crop yield should be decreased due to the reduced absorption of solar radiation by leaves. Thus, before popularizing the AVS, it is necessary to comprehend the degree of shading by PVPs in AVS. In this study, the change of radiation condition under AVS mimic shading net was investigated. The minimum and maximum of difference of photosynthetically active radiation (PAR) between under and outside shading net were 3.03 mol/㎡/day on a cloudy day and 17.08 mol/㎡/day on a sunny day. This difference decreased when the ratio of diffuse irradiance to global irradiance increased. Such a shading effect resulted in the increase of rice height and decrease of rice tillering.

Evaluation of Heat Waves Predictability of Korean Integrated Model (한국형수치예보모델 KIM의 폭염 예측 성능 검증)

  • Jung, Jiyoung;Lee, Eun-Hee;Park, Hye-Jin
    • Atmosphere
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    • v.32 no.4
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    • pp.277-295
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    • 2022
  • The global weather prediction model, Korean Integrated Model (KIM), has been in operation since April 2020 by the Korea Meteorological Administration. This study assessed the performance of heat waves (HWs) in Korea in 2020. Case experiments during 2018-2020 were conducted to support the reliability of assessment, and the factors which affect predictability of the HWs were analyzed. Simulated expansion and retreat of the Tibetan High and North Pacific High during the 2020 HW had a good agreement with the analysis. However, the model showed significant cold biases in the maximum surface temperature. It was found that the temperature bias was highly related to underestimation of downward shortwave radiation at surface, which was linked to cloudiness. KIM tended to overestimate nighttime clouds that delayed the dissipation of cloud in the morning, which affected the shortage of downward solar radiation. The vertical profiles of temperature and moisture showed that cold bias and trapped moisture in the lower atmosphere produce favorable conditions for cloud formation over the Yellow Sea, which affected overestimation of cloud in downwind land. Sensitivity test was performed to reduce model bias, which was done by modulating moisture mixing parameter in the boundary layer scheme. Results indicated that the daytime temperature errors were reduced by increase in surface solar irradiance with enhanced cloud dissipation. This study suggested that not only the synoptic features but also the accuracy of low-level temperature and moisture condition played an important role in predicting the maximum temperature during the HWs in medium-range forecasts.

Effect of High Temperature, Daylength, and Reduced Solar Radiation on Potato Growth and Yield (고온, 일장 및 저일사 조건이 감자 생육 및 수량에 미치는 영향)

  • Kim, Yean-Uk;Lee, Byun-Woo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.18 no.2
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    • pp.74-87
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    • 2016
  • Potato phenology, growth, and yield are projected to be highly affected by global warming in the future. The objective of this study was to examine the responses of potato growth and yield to environmental elements like temperature, solar radiation, and daylength. Planting date experiments under open field condition were conducted using three cultivars differing in maturity group (Irish Cobbler and Superior as early; Atlantic as mid-late maturing) at eight different planting dates. In addition, elevated temperature experiment was conducted in four plastic houses controlled to target temperatures of ambient temperature (AT), $AT+1.5^{\circ}C$, $AT+3^{\circ}C$, and $AT+5^{\circ}C$ using cv. Superior. Tuber initiation onset was found to be hastened curve-linearly with increasing temperature, showing optimum temperature around $22-24^{\circ}C$, while delayed by longer photoperiod and lower solar radiation in Superior and Atlantic. In the planting date experiments where the average temperature is near optimal and solar radiation, rainfall, pest, and disease are not limiting factor for tuber yield, the most important determinant was growth duration, which is limited by the beginning of rainy season in summer and frost in the late fall. Yield tended to increase along with delayed tuber initiation. Within the optimum temperature range ($17^{\circ}-22^{\circ}C$), larger diurnal range of temperature increased the tuber yield. In an elevated temperature treatment of $AT+5.0^{\circ}C$, plants failed to form tubers as affected by high temperature, low irradiance, and long daylength. Tuber number at early growth stage was reduced by higher temperature, resulting in the decrease of assimilates allocated to tuber and the reduction of average tuber weight. Stem growth was enhanced by elevated temperature at the expense of tuber growth. Consequently, tuber yield decreased with elevated temperature above ambient and drop to almost nil at $AT+5.0^{\circ}C$.

Analysis of Temperature Influence Experiment on Green Spaces in Campus (캠퍼스 내 녹지공간의 온도분석 및 온도영향요인 규명 실험)

  • Kim, Jaekyoung;Kim, Wonhee;Kim, Eunil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.511-520
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    • 2020
  • Owing to global warming, heat waves have become stronger in the summer, and research on improving the thermal environment of green spaces, such as urban parks, is being conducted. On the other hand, studies on improving the urban thermal environment, which is changing due to the greening pattern and the intensity of the wind, are still insufficient. This study analyzed the temperature of the green spaces on campus to understand the factors affecting the temperature changes. After investigating the covering condition and planting form of the site, factors, such as temperature, humidity, wind direction, wind speed, and illuminance, were measured. The most influential factors on the temperature distribution are evapotranspiration and wind - induced heat transfer. The other major factors affecting the temperature change were the type of cover, wind velocity/wind direction, type of planting, shade / solar irradiance. In the type of cover, the plant was classified as low temperature, and the asphalt pavement was classified as high temperature. In wind speed, instantaneous temperature was reduced by 1.2 ℃ in southern wind, 0.7 ℃ in the westerly wind, 0.4 ℃ in the north wind and 0.5 ℃ in the east wind when a wind of 3.5m/s or more was blown.