• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.285-290
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• 1983

Two methods were tested to establish the cropping period for rice cultivation using the meteorological data. The Hanyu-Uchijima method was based on the normal average temperature to select the earliest possible transplanting date (ETD), the earliest heading date (EHD), the optimum heading date (OHD) and the latest maturing date (LMD). The probability method was based on the temperature occurrence probability. The cropping period based on the probability method gave higher stability than H-U method for year variability. The ETD by the probability of 75 to 90 percents was May 12 to 22 for northern part of Korea, May 15 to 25 for east coastal area and May 4 to 16 for southern part, respectively. In Chuncheon area, the rice varieties requiring more than 1700 degree-days from transplanting to heading might not be appropriate due to low temperature condition and those requiring 1900 degree days were not allowable in Kangreung area. The OHD was July 30 to August 8 in northern part of the country and August 11 to 16 in southern part for Tongil varieties which demand higher temperature than common Japonica varieties. The OHD for Japonica varieties were 5 to 7 days later than Tongil varieties. The LMD was September 30 to October 2 in northern part, October 13 to 14 in east costal area and October 7 to 14 in southern part, and was earlier than the first frost date.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.1029-1040
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• 2017

Wildfires release a large amount of greenhouse gases (GHGs) into the atmosphere. Fire radiative power (FRP) data obtained from geostationary satellites can play an important role for tracing the GHGs. This paper describes an estimation of the Himawari-8 FRP and fire emissions for Samcheock and Gangnueng wildfire in 6 May 2017. The FRP estimated using Himawari-8 well represented the temporal variability of the fire intensity, which cannot be captured by MODIS (Moderate Resolution Imaging Spectroradiometer) because of its limited temporal resolution. Fire emissions calculated from the Himwari-8 FRP showed a very similar time-series pattern compared with the AirKorea observations, but 1 to 3 hour's time-lag existed because of the distance between the station and the wildfire location. The estimated emissions were also compared with those of a previous study which analyzed fire damages using high-resolution images. They almost coincided with 12% difference for Samcheock and 2% difference for Gangneung, demonstrating a reliability of the estimation of fire emissions using our Himawari-8 FRP without high-resolution images. This study can be a reference for estimating fire emissions using the current and forthcoming geostationary satellites in East Asia and can contribute to improving accuracy of meteorological products such as AOD (aerosol optical depth).

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.947-960
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• 2017

Soil moisture plays an important role to affect the Earth's radiative energy balance and water cycle. In general, satellite observations are useful for estimating the soil moisture content. Passive microwave satellites have an advantage of direct sensitivity on surface soil moisture. However, their coarse spatial resolutions (10-36 km) are not suitable for regional-scale hydrological applications. Meanwhile, in-situ ground observations of point-based soil moisture content have the disadvantage of spatially discontinuous information. This paper presents an experimental soil moisture retrieval using Sentinel-1 SAR (Synthetic Aperture Radar) with 10m spatial resolution for cropland in South Korea. We developed a soil moisture retrieval algorithm based on the technique of linear regression and SVR (support vector regression) using the ground observations at five in-situ sites and Sentinel-1 SAR data from April to October in 2015-2017 period. Our results showed the polarization dependency on the different soil sensitivities at backscattered signals, but no polarization dependence on the accuracies. No particular seasonal characteristics of the soil moisture retrieval imply that soil moisture is generally more affected by hydro-meteorology and land surface characteristics than by phenological factors. At the narrower range of incidence angles, the relationship between the backscattered signal and soil moisture content was more distinct because the decreasing surface interference increased the retrieval accuracies under the condition of evenly distributed soil moisture (during the raining period or on the paddy field). We had an overall error estimate of RMSE (root mean square error) of approximately 6.5%. Our soil moisture retrieval algorithm will be improved if the effects of surface roughness, geomorphology, and soil properties would be considered in the future works.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.203-209
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• 1983

The occurrence and regional distribution of low temperature and drought during rice cropping period in Korea were studied to characterize the climatic impacts. The long term changes in rice yield, air temperature and precipitation were analyzed, and regional distributions were characterized. The significant climatic impacts on rice yield were heavy rain or flood, drought and low temperature. Since 1910, the occurrence of drought was 29 times, that of flood was 24 times and that of low temperature was 9 times; however, the drought and flood damages were decreased due to expansion of irrigation system since 1970 but low temperature damage was remarkedly increased. The long term changes in air temperature since 1908 in Suweon showed that the 5-year moving average from July to August decreased while that from May to June increased. The occurrence probability of the long term and early term low temperature types were the greatest in Korea and were in order of Suweon, Daegu and Kwangiu. The long term changes in 10-year moving average precipitation from April to June showed a 15 year cycle and recent years were in low precipitation period. The drought frequencies were the highest in Daegu and Pohang area. According to the precipitation from April to June and resevtoir storage at late June, the severest dry area were the Youngnam inland and the southwest coastal area.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.367-378
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• 2007

We present a software which we developed for the multi-purpose CCD camera. This software can be used on the all 3 types of CCD - KAF-0401E ($768{\times}512$), KAF-1602E ($1536{\times}1024$), KAF-3200E ($2184{\times}1472$) made in KODAK Co.. For the efficient CCD camera control, the software is operated with two independent processes of the CCD control program and the temperature/shutter operation program. This software is designed to fully automatic operation as well as manually operation under LINUX system, and is controled by LINUX user signal procedure. We plan to use this software for all sky survey system and also night sky monitoring and sky observation. As our results, the read-out time of each CCD are about 15sec, 64sec, 134sec for KAF-0401E, KAF-1602E, KAF-3200E., because these time are limited by the data transmission speed of parallel port. For larger format CCD, the data transmission is required more high speed. we are considering this control software to one using USB port for high speed data transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1506-1514
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• 2015

In this paper, we proposed a forest fires prediction and detection system. It could provide a situation of fire prediction and detection methods using context awareness sensor. A fire occurs wide range of sensing a fire in a single camera sensor, it is difficult to detect the occurrence of a fire. In this paper, we propose an algorithm for real-time by using a temperature sensor, humidity, Co2, the flame presence information acquired and comparing the data based on multiple conditions, analyze and determine the weighting according to fire in complex situations. In addition, it is possible to differential management of intensive fire detection and prediction for required dividing the state of fire zone. Therefore we propose an algorithm to determine the prediction and detection from the fire parameters as an temperature, humidity, Co2 and the flame in real-time by using a context awareness sensor and also suggest algorithm that provide the path of fire diffusion and service the secure safety zone prediction.

• Atmosphere
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• v.22 no.1
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• pp.29-45
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• 2012

An unusual autumn storm developed rapidly in the western part of the East sea on the early morning of 23 October 2006. This storm produced a record-breaking heavy rain and strong wind in the northern and middle part of the Yeong-dong region; 24-h rainfall of 304 mm over Gangneung and wind speed exceeding 63.7 m $s^{-1}$ over Sokcho. In this study, MTSAT-1R (Multi-fuctional Transport Satellite) water vapor and infrared channel imagery are examined to find out some features which are dynamically associated with the development of the storm. These features may be the precursor signals of the rapidly developing storm and can be employed for very short range forecast and nowcasting of severe storm. The satellite features are summarized: 1) MTSAT-1R Water Vapor imagery exhibited that distinct dark region develops over the Yellow sea at about 12 hours before the occurrence of maximum rainfall about 1100 KST on 23 October 2006. After then, it changes gradually into dry intrusion. This dark region in the water vapor image is closely related with the positive anomaly in 500 hPa Potential Vorticity field. 2) In the Infrared imagery, low stratus (brightness temperature: $0{\sim}5^{\circ}C$) develops from near Bo-Hai bay and Shanfung peninsula and then dissipates partially on the western coast of Korean peninsula. These features are found at 10~12 hours before the maximum rainfall occurrence, which are associated with the cold and warm advection in the lower troposphere. 3) The IR imagery reveals that two convective cloud cells (brightness temperature below $-50^{\circ}C$) merge each other and after merging it grows up rapidly over the western part of East sea at about 5 hours before the maximum rainfall occurrence. These features remind that there must be the upward flow in the upper troposphere and the low-layer convergence over the same region of East sea. The time of maximum growth of the convective cloud agrees well with the time of the maximum rainfall.

• Research in Plant Disease
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• v.21 no.4
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• pp.309-314
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• 2015

Xylogone ganodermophthora (Xg) is an ascomycetous fungus that causes yellow rot on cultivated Ganoderma lucidum. Previously, we reported in vitro antifungal activities of a Xg culture extract against several watermelon pathogens. In 2014, we conducted greenhouse experiments to evaluate the control efficacy of a water extract of cultured Xg on watermelon powdery mildew (WPM). The test material (stock solution, ca. $4,000{\mu}g/ml$) was prepared by an autoclaved Xg culture in water at a ratio of 800 g of culture per 6 liter of water, and then filtering it through filter paper. Six foliar applications of the solutions (diluted 100- and 1,000-fold) significantly suppressed the formation of conidiophores and conidia. The inhibitory effect of aqueous potassium phosphonate solution on the disease and its phytotoxicity was tested. Phytotoxicity on watermelon plants was observed at concentrations of 1,000 and $2,000{\mu}g/ml$ as irregular brownish spots. The control efficacies against WPM were 91.9% at $2,000{\mu}g/ml$, 64.9% at $1,000{\mu}g/ml$, and 62.2% at $500{\mu}g/ml$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.5
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• pp.397-405
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• 2015

Currently, Korea's digital maps are being produced through traditional aerial photogrammetry methods. Aerial photogrammetry is the most economical way to produce a map of a wide area. However, timely survey is not allowed depends on weather condition and it is inefficient for small area surveying in economic point of view. Therefore, it costs too much and needs long time to produce a map for various small areas where are terrestrial changes for updating the map. In contrast, UAV photogrammetry is possible to work even in cloudy weather because of shooting at low altitude below the clouds. It also has excellent mobility and shoot quickly and well suited for small-scale mapping in several places by low cost. In this study, we produced an ortho-photo and digital map with the UAV photogrammetry method using SIFT and SfM algorithm and verified its accuracy to evaluate the applicability for future digital map updates. The accuracy was verified by comparing the results of the ground survey for check points selected on the digital map. Test results show small errors at ±2.6cm in X coordinates, ±2.8cm in Y coordinates and ±5.8cm in height and we could find a possibility that UAV photogrammetry would be fully applicable for digital map updating.

• Korean Journal of Remote Sensing
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• v.30 no.2
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• pp.259-274
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• 2014

On Aug 18, 2013, Sakurajima volcano in Japan erupted on a relatively large-scale. Geostationary Ocean Color Imager (GOCI) had used to detect volcanic ash in the surrounding area on the next day of this eruption. The geomagnetic variation has been analyzed using geomagnetic data from Cheongyang observatory in Korea and several geomagnetic observatories in Japan. First, we reconstruct geomagnetic data by principal component analysis and conduct semblance analysis by wavelet transform. Secondly, we minimize the error of solar effect by using wavelet based semblance filtering with Kp index. As a result of this study, we could confirm that the geomagnetic variation usually occur at the moment of Sakurajima volcano eruption. However, we cannot rule out the possibilities that it could have been impacted by other factors besides volcanic eruption in other variation's cases. This research is an exceptional study to analyze geomagnetic variation related with abroad volcanic eruption uncommonly in Korea. Moreover, we expect that it can help to develop further study of geomagnetic variation involved in earthquake and volcanic eruption.