• Atmosphere
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• v.28 no.4
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• pp.383-392
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• 2018

This study investigates synoptic characteristics of cold surges over South Korea during winter season (December-February). A total of 63 cold events are selected by quantile regression analysis using daily mean temperature observations from 11 KMA stations for 38 years (1979/80-2016/17). Large-scale pressure pattern during the cold surges is well characterized by high over Siberia and low over Aleutian regions, which elucidates cold advection over the Korean peninsula. However, the large-scale pattern cannot successfully explain the observed sudden decrease of temperature during the cold surges. Composite analyses reveal that a synoptic-scale cyclone developing over the northern Japan is a key feature that significantly contribute to the enhancement of cold advection by increasing pressure gradient over the Korean peninsula. Enhanced sensible and latent heat fluxes are observed over the southern ocean of Korea and Japan during the cold surges due to temperature and humidity differences between the near surface and the lower atmosphere over the ocean. The evaporated water vapor transported toward the center of the surface cyclone and condenses in the lower-to-middle troposphere. The released energy likely promotes the development of the surface cyclone by inducing positive PV near the surface of the heating region.

• Journal of Forest and Environmental Science
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• v.37 no.3
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• pp.235-242
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• 2021

Seed morphology, physiology and environmental conditions have influence on germination of any tropical seeds and their appropriate handling, processing and handling enhances seeds emergent. This study therefore investigated effects of storage durations under different temperatures on germination of Bombax costatum seeds from different provenances. Fresh 25 seeds of B. costatum in four replicates were collected from four different provenances (Aponmu, Oluwa, Ibadan and Oyo). They were surface sterilized, thoroughly washed in distilled water and stored at four different temperature regimes: 28℃, 21℃, 5℃ and -17℃. Samples were taken every 2 months for germination test for 18 months. Germination assessment was carried out daily and recorded. The experimental design was 4×4×10 factorial in 4 replicates. Data were subjected to percentages and analysis of variance (ANOVA). Results showed that there were significant differences among storage temperatures, storage durations and provenances on germination percentage. Freshly collected seeds from Aponmu and Oyo had the highest mean germination of 100% followed by seeds from Ibadan (89.3%). Seeds from Oyo provenance stored 5℃ had germination of 94.0%, 88.70% and 78.7% at 2nd, 4th and 6th month respectively. Seeds from Ibadan and Oyo stored at 28℃, 21℃ recorded 0.0% starting from 8 months of storage. Germination of B. costatum seeds from the four provenances decreased with increase in storage duration at different temperatures.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.1
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• pp.29-35
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• 2022

This study was conducted to investigate the seed storage method and seed germination characteristics of Synurus deltoides (Ait.) Nakai, a kind of wild vegetables. Several parameters affecting seed germination, such as germination temperature, chilling duration, imbibition duration, and storage method were evaluated. The seed germination of Synurus deltoides showed the highest germination rate (GR), promptness index (PI), germination performance index (GPI), mean daily germination (MDG) at 25℃. This implies that the optimum germination temperature was 25℃. And also, Seeds stored at -4℃, after 150 days showed relatively high germination rate about 98%. Therefore, The optimum germination temperature of Synurus deltoides was 25℃ and to increase the germination rate over 98% of Synurus deltoides, cold-wet storage 20 days treatments at 4℃ were effective in the improvement of seed germination.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.103-103
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• 2019

본 연구에서는 Terra MODIS 위성영상과 Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) 모형을 이용하여 2012년부터 2017년까지 한반도 전국의 증발산량을 산정하고 플럭스 타워 실측 증발산량과 비교하였다. METRIC은 전 세계에 널리 적용된 바 있는 에너지 수지 기반의 Surface Energy Balance Algorithm for Land (SEBAL) 모형의 개념과 기술을 기반으로 현열(Sensible Heat Flux) 추정 모듈을 개선한 모형이다. 본 연구에서 METRIC 모형은 기존 C#으로 개발되어 있던 SEBAL 코드에서 현열 추정 모듈을 수정하였고 연산 속도 개선을 위해 Python으로 재작성하였다. METRIC 모형의 위성 자료로 Terra MODIS 위성의 MOD13A2(16day, 1km) NDVI, MOD11A1(Daily, 1km) Land Surface Temperature (LST) 및 MCD43A3(Daily, 500m) Albedo를 구축하였으며 500m 공간해상도의 Albedo는 1000m 해상도로 resample하여 활용하였다. 기상자료는 기상청 기상관측소의 풍속, 풍속측정높이, 습도, 10분 간격 이슬점 온도, 일사량 자료를 위성 자료와 같은 공간해상도로 내삽(Interpolation)하여 구축하였다. 모형결과 검증을 위해 국내 플럭스 타워 (설마천, 청미천, 덕유산) 증발산량 관측 자료와의 결정계수(Coefficient of determination, $R^2$), RMSE(Root mean square error) relative RMSE (RMSE%), Nash-Sutcliffe efficiency (NSE) 및 IOA(Index of Agreement)를 산정하고, 기존 SEBAL 모형 결과와의 비교를 통해 본 모형의 개선점을 보이고자 한다.

• Atmosphere
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• v.24 no.4
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• pp.541-554
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• 2014

Historical, RCP4.5 and RCP8.5 scenarios from HadGEM2-AO are dynamically downscaled over the northeast East Asia with WRFV3.4. The horizontal resolution of the produced data is 12.5 km and the periods of integration are 1979~2010 for historical and 2019~2100 for both RCP4.5 and RCP8.5. We analyze the time series, climatology, EOF and extreme climate in terms of 2 m-temperature and precipitation during 30-year for the Historical (1981~2010) and RCP4.5 and RCP8.5 (2071~2100) scenarios. According to the result, the temperature of the northeast Asia centered at the Korean Peninsula increase 2.9 and $4.6^{\circ}C$ in the RCP4.5 and RCP8.5 scenarios, respectively, by the end of the 21st century. The temperature increases with latitude and the increase is larger in winter rather than in summer. The annual mean precipitation is expected to increase by about $0.3mm\;day^{-1}$ in RCP4.5 scenario and $0.5mm\;day^{-1}$ in RCP8.5 scenario. The EOF analysis is also performed for both temperature and precipitation. For temperature, the EOF $1^{st}$ modes of all scenarios in summer and winter show that temperature increase with latitude. The $2^{nd}$ mode of EOF of each scenario shows the natural variability, exclusive of the global warming. The summer precipitation over the Korean Peninsula projected increases in EOF $1^{st}$ modes of all scenarios. For extreme climate, the increment of the number of days with daily maximum temperature above $30^{\circ}C$ per year ($DAY_{TX30}$) is 25.3 and 49.7 days in RCP4.5 and RCP8.5 respectively over the Korean Peninsula. The number of days with daily precipitation above $20mm\;day^{-1}$ per year ($DAY_{PR20}$) also increases 3.1 and 3.5 days in RCP4.5 and RCP8.5 respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.78-82
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• 2022

Phenology determines the timing of crop development, and the timing of phenological events is strongly influenced by the temperature during the growing season. In process-based model, leaf area is simulated dynamically by coupling of morphology and phenology module. Therefore, the prediction of leaf appearance rate and final leaf number affects the performance of whole crop model. The dataset for the model equation was collected from SPA R chambers with five different temperature treatments. Beta distribution function (proposed by Yan and Hunt (1999)) was used for describing the leaf appearance rate as a function of temperature. The optimum temperature and the critical value were estimated to be 26.0℃ and 35.3℃, respectively. For evaluation of the model, the accumulated number of onion leaves observed in a temperature gradient chamber was compared with model estimates. The model estimate is the result of accumulating the daily increase in the number of onion leaves obtained by inputting the daily mean temperature during the growing season into the temperature model. In this study, the coefficient of determination (R²) and RMSE value of the model were 0.95 and 0.89, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1488-1494
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• 2011

In this paper, we propose an algorithm using linear regression model that forecasts the demand of heated water in winter. To supply heated water to apartments, stores and office buildings, Korea District Heating Corp.(KDHC) operates boilers including electric power generators. In order to operate facilities generating heated water economically, it is essential to forecast daily demand of heated water with accuracy. Analysis of history data of Kangnam Branch of KDHC in 2006 and 2007 reveals that heated water supply on previous day as well as temperature are the most important factors to forecast the daily demand of heated water. When calculated by the proposed regression model, mean absolute percentage error for the demand of heated water in winter of the year 2006 through 2009 does not exceed 3.87%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.5
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• pp.343-345
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• 2008

This study determined the optimum feeding frequency for the growth of juvenile cherry salmon (Oncorhynchus masou). Triplicate groups of fish (initial mean weight 19.1 g) were fed extruded pellets at four feeding frequencies for 50 days: once every 2 days, once a day, twice a day, and three times a day. The mean water temperature during the feeding trial was $17.9{\pm}1.59^{\circ}C$. The survival of all groups was 100%. The final fork length of fish fed twice a day was significantly greater than that of the other groups (P<0.05). The weight gain of fish fed two and three times daily was significantly greater than that of fish fed once a day or every 2 days (P<0.05). The daily feed intake increased significantly with feeding frequency (P<0.05), but there was no significant difference in the weight gain of fish fed two or three times a day. The feed efficiency of fish fed once every 2 days was highest (P<0.05), and the feed efficiency of fish fed two or three times a day was significantly higher than that of fish fed once a day (P<0.05). The results of this study indicated that the optimum feeding frequency for the growth of juvenile cherry salmon is twice a day, while the feeding efficiency of fish fed once every 2 days was best.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.128-134
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• 2020

The daily gridded meteorological information and climatology with high resolution (30m and 270m) was produced from 94 Automated Surface Observing System (ASOS) of Korea Meteorological Administration (KMA) for the past 50 years (1971-current) by different downscaling methods. In addition, the difference between daily meteorological data and the mean state of past 30 years (1981-2010) was calculated for the analysis of climate change. These datasets with GeoTiff format are available from the web interface (https://agecoclim. agmet.kr). The performance of the data is evaluated using 172 Automatic Weather S tation (AWS ) of Rural Development of Administration (RDA). The data have biases lower than 2.0, and root mean square errors (RMSE) lower than 3.8. This data may help to better understand the regional climatic change and its impact on agroecosystem in S outh Korea.

• Food Science and Preservation
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• v.11 no.2
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• pp.282-285
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• 2004

This experiment was carried out to investigate the cost reduction of rhizome through the stable storage of Jiwhang #1(Rehmannia glutinosa Libosch). The growth characteristics of Jiwhang #1 are different from those of local Rehmannia glutinosa L. varieties in Korea. Various storage methods was introduced and analyzed for 120 days. Among storage methods, changes in mean daily temperature in storage location were the least from 7.2 to 13.8$^{\circ}C$ in underground storage, while those were wide in styrofoam box filled with soil, and changes in mean daily relative humidity were the highest 98.2% in underground storage. As the storage period increased, the rhizome brix and the rate of rhizome loss and spoiled rhizome increased. The brix and loss rate of rhizome were higher in net sack filled with hull and styrofoam box filled with hull, but the rate of spoiled rhizome was the greatest in underground storage among storage methods. As the storage period increased, the hardness of rhizome epidermis increased, while that of rhizome endodermis decreased.