• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.2
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• pp.71-77
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• 2024

After the strongest El Niño since 2015 occurred in 2023, there has been a growing interest in understanding its impacts on rice yield in South Korea. We investigated the impact of El Niño during the rice-growing season on rice yield by analyzing the correlation between detrended rice yield data and ONI (Oceanic Niño Index) values exceeding 0.5. The results show a positive correlation between ONI intensities and detrended rice yields. Furthermore, we found that variations in sunshine duration, precipitation, and typhoon activity affect detrended yield values positively and negatively. This pattern was similar to the classification of El Niño into Cold Tongue El Niño and non-Cold Tongue El Niño, which showed positive and negative detrended rice yield values, respectively. This observation suggests that predicting yield based on ONI intensity during Cold Tongue El Niño years may be feasible to some extent.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.330-336
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• 2022

It is likely that the heading would occur early when air temperature increases. In 2022, however, the heading date was delayed unusually, e.g., by 3 to 5 days although temperature during the vegetative growth stage was higher than normal years. The objective of this study was to identify the cause of such event analyzing weather variables including average temperature, sunshine hours, and day-length for each growth stage. The observation data were collected for medium-late maturing varieties, which has been grown at crop yield experiment sites including Daegu, Andong, and Yesan. The difference in heading date was compared between growing seasons in 2021 and 2022 because crop management options, e.g., the cultivars and cultivation methods, were identical at those sites during the study period. It appeared that the heading date was delayed due to the difference in temperature responsiveness under a given day-length condition The effect of the temperature increase on the heading date differed between the periods during which when the day-length was more than 14.3 hours before and after the summer-solstice.. The effect of the temperature decrease during the period from which the day-length decreased to less than 14.3 hours to the heading date was relatively greater. This merits further studies to examine the response of rice to the temperature change under different day-length and sunshine duration in terms of heading.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.234-245
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• 2019

In order to select the best varieties and cultivation methods for the production of domestic wheat for Hodugwaja(a walnut shaped confection), we carried out a 3-year experiment (2015~2017) to investigate the effect of different factors (crop variety, planting date, nitrogen fertilization) in a double cropping system (wheat then rice) on crop yields in the Cheonan area. Rice is the second crop in the system, and requires an accumulated temperature for 40 days of about $840{\sim}930^{\circ}C$ to ensure ripening. Transplanting dates for rice between June 29 and July 6 were suitable; transplanting on or after July 13 does not ensure ripening. The daily hours of sunshine ranged from 6.3 to 6.5 hours, which were slightly higher than the optimum of 6.0 to 6.1 hours. The higher the nitrogen fertilizer treatment, the higher culm length, and spike length of wheat. The yield of wheat per 10a tended to increase as the amount of nitrogen fertilizer increased. Wheat yields were highest for the Sooan variety, followed by Goso, followed by Keumgang. The number of days from transplanting to heading of rice were shortest for the Jopyeong variety followed by Unkwang, followed by Haedam. The yield of milled rice per 10a increased as the transplanting date was earlier and the transplanting date of June 9 showed the average yield of more than 500 kg in three varieties. From the results of the experiment, we recommend the Goso wheat variety and the Haedam rice variety for growing in a double cropping system under the climatic conditions of the Cheonan area.

• Journal of Cadastre & Land InformatiX
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• v.49 no.1
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• pp.17-27
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• 2019

In this study, we conducted a study to predict the photovoltaic power by constructing the sensor based meteorological data observation system and the accurate terrain data obtained by using LiDAR surveying. The average sunshine hours in 2018 is 4.53 hours and the photovoltaic power is 2,305 MWh. In order to analyze the effect of photovoltaic power on the installation angle of solar modules, we installed module installation angle at $10^{\circ}$ intervals. As a result, the generation time was 4.24 hours at the module arrangement angle of $30^{\circ}$, and the daily power generation and the monthly power generation were the highest, 3.37 MWh and 102.47 MWh, respectively. Therefore, when the module arrangement angle is set to $30^{\circ}$, the generation efficiency is increased by about 4.8% compared with the module angle of $50^{\circ}$. As a result of analyzing the influence of the seasonal photovoltaic power by the installation angle of the solar module, it was found that the photovoltaic power was high in the range of $40^{\circ}{\sim}50^{\circ}$, where the module angle was large from November to February when the weather was cold. From March to October, it was found that the photovoltaic power amount is $10^{\circ}{\sim}30^{\circ}$ with small module angle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.444-450
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• 1995

It was very hard to gather the seeds of Eleutherococcus senticosus Max. known as a medicinal plant for they tend to drop under the high temperature condition during the summer period in Korea. Therefore, this study was conducted to select seed production site for Eleutherococcus senticosus in Korea, comparing the climate of Hokkaido of Japan, in which the seeds have been produced, with that of various place in this country. It was low that the average maximum temperature during the hottest summer two months (July and August) as a 24.4$^{\circ}C$ in Hokkaido and 21.2$^{\circ}C$ in Daegwanryeong compared with 27.4$^{\circ}C$ in Changsu. Especially in Daegwanryeong, average maximum temperature from June to September remained as low as 21$^{\circ}C$. Effective accumulated temperature(>5$^{\circ}C$) was 807$^{\circ}C$ in Hokkaido and 964$^{\circ}C$ in Daegwanryeong during the ripening period. Monthly sunshined hours from July to August were 121.7~128 hours in Daegwanryeong and 83.5~85.4 hours in Hokkaido. The Eleutherococcus senticosus sprouts at 8.5$^{\circ}C$, comes to flowering season in mid-August, and ripens during late-August and October in Hokkaido, the climate of which is similar to that of Daegwanryeong.

• Advances in Energy Research
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• v.5 no.2
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• pp.179-205
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• 2017

This research presents an in-depth analysis of location planning of the solar-hydrogen power plants for electricity production in different cities situated in Kerman province of Iran. Ten cities were analyzed in order to select the most suitable location for the construction of a solar-hydrogen power plant utilizing photovoltaic panels. Data envelopment analysis (DEA) methodology was applied to prioritize cities for installing the solar-hydrogen power plant so that one candidate location was selected for each city. Different criteria including population, distance to main road, flood risk, wind speed, sunshine hours, air temperature, humidity, horizontal solar irradiation, dust, and land costare used for the analysis. From the analysis, it is found that among the candidates' cities, the site of Lalezar is ranked as the first priority for the solar-hydrogen system development. A measure of validity is obtained when results of the DEA method are compared with the results of the technique for ordering preference by similarity to ideal solution (TOPSIS). Applying TOPSIS model, it was found that city of Lalezar ranked first, and Rafsanjan gained last priority for installing the solar-hydrogen power plants. Cities of Baft, Sirjan, Kerman, Shahrbabak, Kahnouj, Shahdad, Bam, and Jiroft ranked second to ninth, respectively. The validity of the DEA model is compared with the results of TOPSIS and it is demonstrated that the two methods produced similar results. The solar-hydrogen power plant is considered for installation in the city of Lalezar. It is demonstrated that installation of the proposed solar-hydrogen system in Lalezar can lead to yearly yield of 129 ton-H2 which covers 4.3% of total annual energy demands of the city.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.3941-3954
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• 2020

In this paper, the climate change in Haiyan County in recent decades was analyzed in detail with the methods of moving average, Mann-Kendall non-parametric mutation test and wavelet analysis. According to the variation trend of meteorological factors such as temperature, relative humidity, wind speed, pan evaporation and precipitation in recent decades, the climate of Haiyan County has a tendency of drought, which is becoming more and more serious. From the results of the analysis, the sunshine hours and the air temperature in Haiyan County have an obvious upward trend. The average surface temperature has increased by 2.75 ℃ from 1976, and its largest increase occurred in the late 1970s and 1980s. At this stage, the average surface temperature increased by 1.37 ℃. The relative humidity has a decreasing trend that has decreased by 2.75％. From 1976 to the present, there are two quasi-3a cycles and one quasi-6a cycle. The precipitation and evaporation showed the opposite change trend, in which the trend of precipitation fluctuated upward, while the trend of evaporation showed a fluctuating downward tendency, which led to the serious loss of water in the feeding area. The wind direction in Haiyan County are mainly from west to east, and its wind speed has a trend of slight increase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.1
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• pp.19-24
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• 1984

Experiment was conducted to know the interaction of temperature and solar radiation for spikelet formation of rice in different location. Under the Korea climatic conditions both number of spikelets and percentage of ripened grains affected yield of rice. Percentage of ripened grains was the most significant limiting factor in Tongil type rice varieties and the lower number of spikelets in japonica type varieties. The number of spikelets increased as amounts of solar radiation increased during the reproductive stage, as daily air temperature decreased from 23 to 28$^{\circ}C$, or as climatic consumption index (CCI) value decreased. CCI calculated with critical temperature of 1$0^{\circ}C$ and solar radiation was more closely correlated with the number of spikelets compared to CCI calculated with sunshine hours instead of solar radiation. CCI during the 15 days before heading was more closely related with the number of spikelets compared to CCI during the 30 days before heading.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.310-313
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• 1985

Seven years data on the yield of ginseng seedling were investigated to define the relations between meteorological conditions and yield of ginseng seedling. Variation of meteorological factors by years are showed in the order precipitation, hours of sunshine and temperature. The variation of temperature by years was biggest in June, whereas smallest figure in April. Variation of yield of ginseng seedling in different quality by years was biggest in number of short weighted seedling and least in that of usable seedling. Highly significant correlations were confirmed between number of usable seedling and number of total seedling, and between number of total seedling and precipitation from January to March, respectively. A significant negative correlation was recognized between the number of usable seedling and temperature in July but correlation between number of usable seedling and precipitation in May was positive. It suggests that water management in seedbed have to be started from May.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.75-81
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• 2008

The water shortage in mega cities in Asia, which face a rapid growth in urban population, is an outstanding problem. It is important, therefore, to accurately estimate the water balance in each city in order to use the limited water resources effectively. In this study, we estimated the potential water resources in し sixteen mega cities in Asia. The target cities were Delhi and Calcutta, India; Colombo, Sri Lanka; Dhaka, Bangladesh; Yangon, Myanmar; Bangkok, Thailand; Kuala Lumpur, Malaysia; Singapore; Jakarta, Indonesia; Hanoi, Vietnam; Beijing and Hong Kong, the People's Republic of China; Seoul, the People's Republic of Korea; Manila, the Philippines, and Sapporo and Tokyo, Japan. The potential water resources were estimated by subtracting the actual evaporation from the amount of rainfall. The actual evaporation was estimated using the potential evaporation obtained by Hamon's equation which requires the air temperature and the possible hours of sunshine. When the results of Hamon's and Penman's evaporation equations were compared, a considerable error appeared in the low latitude region. The estimation using Hamon's equation was corrected with the linear regression line of Hamon's and Penman's equations. A classification of the land cover was carried out based on satellite photographs of the target cities, and the volume of surface runoff for each city was obtained using the runoff ratios which depended on the land cover. As a result, the potential water resources in the above mega cities in Asia were found to be greater than the world average. However, the actual water resources which are available for one person to use are probably very limited.