• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.635-644
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• 2002

Many generating units can be in parallel connection to one battery and inverter. However, one of the biggest problems we encountered is that wind speed is fluctuated sharply in accordance with the unstable weather conditions. To solve this problem, we need energy storage equipment such as storage lead-acid battery. We design a system and analyze its modeling so that it supplies a stable power to the load through DC-AC inverter part. In this paper, we applied dual step-up/down buck-boost converter and dual high-frequency half-bridge converter to the proposed system. These converters are used to store energy in the battery regardless of the change of the wind speed. The operation process of two proposed types of converters for high-power battery charging is discussed along with simulation and experimental result. We design a charging circuit which is applicable in the actual wind power generation system for 30kw and confirm the circuit's validity.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.499-507
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• 2018

Agricultural meteorological information is an important resource that affects farmers' income, food security, and agricultural conditions. Thus, such data are used in various fields that are responsible for planning, enforcing, and evaluating agricultural policies. The meteorological information obtained from automatic weather observation systems operated by rural development agencies contains missing values owing to temporary mechanical or communication deficiencies. It is known that missing values lead to reduction in the reliability and validity of the model. In this study, the hierarchical Bayesian spatio-temporal model suggests replacements for missing values because the meteorological information includes spatio-temporal correlation. The prior distribution is very important in the Bayesian approach. However, we found a problem where the spatial decay parameter was not converged through the trace plot. A suitable spatial decay parameter, estimated on the bias of root-mean-square error (RMSE), which was determined to be the difference between the predicted and observed values. The latitude, longitude, and altitude were considered as covariates. The estimated spatial decay parameters were 0.041 and 0.039, for the spatio-temporal model with latitude and longitude and for latitude, longitude, and altitude, respectively. The posterior distributions were stable after the spatial decay parameter was fixed. root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and bias were calculated for model validation. Finally, the missing values were generated using the independent Gaussian process model.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.401-404
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• 2011

Bromobutide, a paddy field herbicide, can effectively control annual and perennial weeds. It has an excellent weeding effect especially against Monochoria vaginalis and Scirpus juncoides etc. When it is mixed with other herbicides controlling weed spectrum and application timing can be broaden. Bromobutide has stable weeding effects regardless of field and weather conditions, and there is almost no phyototoxic effects to rice.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.67-76
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• 2019

A ground source heat pump (GSHP) system can stable system operation by using underground heat source and has high reliability for energy production. However, wide-spread of the GSHP system is delayed to high initial investment costs. In previous studies, horizontal and unit-type ground heat exchanger (GHX) have developed to overcome disadvantages such as high initial cost. However, these performances of GHXs are greatly influenced by climate and weather conditions. It is necessary to analyze the performance of GHX according to the ground temperature change in the installation site. In this study, the ground temperature of each installation site confirmed and performance of unit-type GHX quantitatively analyzed by numerical analysis. As the result, the performance of the unit type GHX was 33.9 W/m in Seoul, 34.2 W/m in Daejeon, and 37.2 W/m in Busan.The result showed the difference performance of GHX according to local climate was maximum of 9.7%.

• The Plant Pathology Journal
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• v.38 no.1
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• pp.46-51
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• 2022

Rice blast is the most destructive disease threatening stable rice production in rice-growing areas. Cultivation of disease-resistant rice cultivars is the most effective way to control rice blast disease. However, the rice blast resistance is easy to breakdown within years by blast fungus that continually changes to adapt to new cultivars. Therefore, it is important to continuously monitor the incidence of rice blast disease and race differentiation of rice blast fungus in fields. In 2020, a severe rice blast disease occurred nationwide in Korea. We evaluated the incidence of rice blast disease in Yeoju and compared the weather conditions at the periods of rice blast disease in 2019 and 2020. We investigated the races and avirulence genes of rice blast isolates in Yeoju to identify race diversity and genetic characteristics of the isolates. This study will provide empirical support for rice blast control and the breeding of blast-resistant rice cultivars.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.17-24
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• 2021

The use of renewable energy sources for power generation has been steadily increasing. Power generation using renewable energy has the advantage of not generating carbon but has the disadvantage of high volatility depending on the weather. This volatility makes stable power supply difficult. Curtailment is occurring to address volatility. Various facilities are operated together to solve the loss caused by the curtailment. The existing SCADA must be modified for turbine control reflecting the conditions of various facilities. However, since it is difficult to modify SCADA, a modular control system is required. In this study, we propose Modular Control System Based on Closed-Loop Control for Wind Farms. Since the control logic can be changed without modifying SCADA, it is easy to respond to changes. The developed modular control system was evaluated as a lab test and confirmed to operate smoothly. Through future research, the experiment will be conducted by applying a modular control system to the actual wind farm.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.136-140
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• 2023

Rice panicle blast is one of the most serious diseases threatening stable rice production by causing severe damage to rice yields and quality. The disease is easy to occur under low air temperature and frequent heavy rainfall during the heading season of rice. In 2021, a rice panicle blast severely occurred in the Jeonbuk province of Korea. The incidence area of panicle blast accounted for 27.7% of the rice cultivation area of Jeonbuk province in 2021, which was 13.7-times higher than in 2019 and 2.6-times higher than in 2020. This study evaluated the incidence areas of rice panicle blast in each region of Jeonbuk province in 2021. The weather conditions during the heading season of rice, mainly cultivated rice cultivars, and the race diversity of the Jeonbuk isolates were also investigated. It will provide important information for the effective control of the rice panicle blast.

• Journal of the Korean earth science society
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• v.36 no.4
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• pp.315-329
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• 2015

We investigated the characteristics of meteorological conditions related to the strong downslope wind over the leeward side of the Taebaek Mountains during the period 2005~2010. The days showing the strong wind exceeding $14ms^{-1}$ in Gangwon province were selected as study cases. A total of 15 days of strong wind were observed at Sokcho, Gangneung, Donghae, and Taebaek located over the Yeongdong region. Seven cases related to tropical cyclone (3 cases) and heavy snowfall (2 cases) and heavy rainfall (2 cases) over the Yeongdong region were excluded. To investigate the characteristics of the remaining 8 cases, we used synoptic weather chart, Sokcho radiosonde, Gangneung wind profiler and numerical model. The cases showed no precipitation (or ${\leq}1mm\;day^{-1}$). From the surface and upper level weather chart, we found the pressure distribution of southern high and northern low pattern over the Korean peninsula and warm ridge over the Yeongdong region. Inversion layer (or stable layer) and warm ridge with strong wind were located in about 1~3 km (925~700 hPa) over mountains. The Regional Data Assimilation and Prediction System (RDAPS) indicated that warm core and temperature ridge with horizontal temperature gradient were $0.10{\sim}0.23^{\circ}C\;km^{-1}$ which were located on 850 hPa pressure level above mountaintop. These results were summarized as a forecasting guidance of downslope windstorm in the Yeongdong region.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.201-217
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• 2022

The United States is one of the largest producers of major crops such as wheat, maize, and soybeans, and is a major exporter of these crops. Therefore, it is important to estimate the crop production of the country in advance based on reliable long- term weather forecast information for stable crops supply and demand in Korea. The purpose of this study is to improve the seasonal predictability of the agro-climatic indices over the United States by using regional-scale daily temperature. For long-term numerical weather prediction, a dynamical downscaling is performed using Weather Research and Forecasting (WRF) model, a regional climate model. As the initial and lateral boundary conditions of WRF, the global hourly prediction data obtained from the Pusan National University Coupled General Circulation Model (PNU CGCM) are used. The integration of WRF is performed for 22 years (2000-2021) for period from June to December of each year. The empirical quantile mapping, one of the bias correction methods, is applied to the timeseries of downscaled daily mean, minimum, and maximum temperature to correct the model biases. The uncorrected and corrected datasets are referred WRF_UC and WRF_C, respectively in this study. The daily minimum (maximum) temperature obtained from WRF_UC presents warm (cold) biases over most of the United States, which can be attributed to the underestimated the low (high) temperature range. The results show that WRF_C simulates closer to the observed temperature than WRF_UC, which lead to improve the long- term predictability of the temperature- based agro-climatic indices.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.1-9
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• 2022

Equilume light masks had no impact on hastening the resumption of estrous cyclicity in mares maintained in outdoor pastures on the mainland of Korea due to the cold weather conditions. Jeju Island is a major horse-breeding site in Korea and is warmer than the mainland during the winter season. Therefore, the primary objective of this study was to explore the efficiency of the Equilume light mask on the resumption of seasonal estrous cycles in Thoroughbred mares on Jeju Island. A total of 20 nonpregnant mares were randomly divided into the Equilume light mask (n = 9) and stable lighting (n =11) groups. The experiment was performed at seven different horse-breeding farms located on Jeju Island from November 15, 2020, to February 15, 2021. The mares were exposed to the respective lights from 16:00 to 23:00. Follicle size and uterine edema were measured by ultrasound scanning. Body condition scores (BCS) were also monitored during the experiment. Statistical analysis was conducted using the SAS and SPSS software, and p-values of < 0.05 were considered statistically significant. Two of the nine (22.2%) mares in the Equilume light mask group and three of the 11 (27.28%) mares in the stable lighting group were still cycling in December and January, which were considered as all-year-round cycling mares. On February 15, there was no difference between groups in the resumption of early seasonal estrus cycle, which was determined by follicles > 25 mm in addition to uterine edema. All mares in the Equilume light mask group and five of the eight mares (62.5%) in the stable lighting group had resumed cycling. Interestingly, six of the seven mares (87.5%) in the Equilume light mask and four of eight mares (50%) in the stable lighting group had already ovulated on February 15 (p > 0.05), as determined by the presence of a recent corpus luteum. No difference was observed in BCS and uterine edema between groups (p > 0.05). In conclusion, the Equilume light mask can be an effective approach to induce early seasonal estrus cycles of mares in Jeju Island, and it also enhances the efficiency of farm management by reducing labor.