• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.666-672
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• 1997

Twenty years' daily mean air temperature data was used to calculate the critical early seeding date(CESD), the optimum heading date(OHD), the critical late heading date for stable ripening(CHDR) and the critical late ripening date(CLRD) for rice seeded on dry paddy in different agroclimatic zones in Korea. The CESD was defined as the first day with mean air temperature of 13$^{\circ}C$, and the OHD as the first day of the 40 consecutive days with mean air temperature of 22$^{\circ}C$ or above after heading. The CHDR was defined as the date after which the cumulative daily mean air temperature would be at least 76$0^{\circ}C$. Lastly, the CLRD was defined as the last day when daily mean air temperature remains above 15$^{\circ}C$. This information was used for the estimation of periods from the earliest date of seeding to optimum heading date, the latest possible date of heading and the latest possible date of ripening in respective regions. For instance, in Suwon, those respective periods mentioned were found to be 104days, 124days, and 165days.

• Korean journal of food and cookery science
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• v.13 no.1
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• pp.30-39
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• 1997

The purpose of this study was to investigate food services and plate waste of the elementary school children in the urban, rural and suburban areas of Taegu and Kyoungpook province. Statistical data analysis was performed using the SPSS programs for Crosstabs analysis T-test, One-way Anova and Pearson's correlation. The results were as follows: The serving size of rice was greater in suburban area than in rural and urban area by the physical estimation. The amount of soup given was the greatest in rural area. The rate of waste in soup was higher than that of rice. Among side dishes, plate waste rate of braised potato was the highest in rural, then suburban and urban area. There were significant differences (p < .001) among the schools in the three areas. Especially, plate waste rate of cucumber and cabbage salad was the highest in all three areas. Then finally the serving size and plate waste rate of Kimchies were the greatest in rural, then suburban and urban schools. There were significant differences in 'spice pickled cabbage'(p < .001) and 'spice pickled radish'(p < .01) among the three areas. Plate waste amounts of egg soup and pine mushroom soup in urban area were greatest. In rural area, side dishes except egg soup, cabbage salad and Kimchies had a greater amount of plate waste. In suburban areas, there were smaller plate waste amount in rice, but plate waste amounts of pine mushroom soup and beef soup were great. Plate waste rate of rice and 'Kimchies' by children's rating estimation were significantly higher in rural than suburban and urban areas. There were no significant differences in plate waste rate of the given food except braised chicken (p < .001), soup (p < .001) and 'Kimchies' (p < .05) between the physical estimation and the children's rating estimation. Increased satisfaction on food service in most menus resulted decreased plate waste rate. There was a significant degree of satisfaction on the amounts of food served.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.287-295
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• 2021

As facilities such as dam reservoir wetlands and agricultural irrigation reservoir wetlands are built, sedimentation occurs over time through erosion, sedimentation transport, and sediment deposition. Sedimentation issues are very important for the maintenance of reservoir wetlands because long-term sedimentation of sediments affects flood and drought control functions. However, research on resignation has been estimated mainly by empirical formulas due to the lack of available data. The purpose of this study was to calculate and compare the sediment deposition rate by developing a multiple regression model along with actual data and empirical formulas. In addition, it was attempted to identify potential causes of collapse by applying it to 64 reservoir wetlands that suffered flood damage due to the long rainy season in 2020 due to reservoir wetland sedimentation and aging. For the target reservoir, 10 locations including the GaGog reservoir located in Miryang city, Gyeongsangnam province in South Korea, where there is actual survey information, were selected. A multiple regression model was developed in consideration of physical and climatic characteristics, and a total of four empirical formulas and sediment deposition rate were calculated. Using this, the error of the sediment deposition rate was compared. As a result of calculating the sediment deposition rate using the multiple regression model, the error was the lowest from 0.21(m³km²/yr) to 2.13(m³km²/yr). Therefore, based on the sediment deposition rate estimated by the multi-regression model, the change in the available capacity of reservoir wetlands was analyzed, and the effective storage capacity was found to have decreased from 0.21(%) to 16.56(%). In addition, the sediment deposition rate of the reservoir where the overflow damage occurred was relatively higher than that of the reservoir where the piping damage occurred. In other words, accumulating sediment deposition rate at the bottom of the reservoir would result in a lack of acceptable effective water capacity and reduced reservoir flood and drought control capabilities, resulting in reservoir collapse damage.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.604-617
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• 2018

As the depletion of forests became more widespread due to the increase in the number of roads, the research was conducted on the relationship between temperature and humidity in the forests, assuming that the forests around the roads were affected. Through the forest monitoring, the temperature and humidity of coniferous forests and broadleaf forests in Sedong and Gongju areas were observed at three point of 10m, 20m and 30m from the road boundary to the inside of the forest, respectively. In Yeongdong area, for more reliable results, it was observed from the point of 0m, 10m, and 20m. During the study period, so it was expected the change in tree growth was small, the change of temperature and humidity inside the forest by the road was compared with the temperature and humidity from the road to the inside of the forest from September 2017 to January 2018, the changes of temperature and humidity inside the forest due to linear development such as roads were quantitatively analyzed. Using the HOBO data logger (MX2301, Onset Corp.), the temperature and humidity changes of each site were measured, and the average of the changes have been analyzed monthly. In the case of Gongju coniferous forests in September 2017, the average weekly temperature is $0.57^{\circ}C$ higher than the forest outside from the forest boundary and $1.23^{\circ}C$ higher than the inside of the forest, at night in November 2017, in Sedong broadleaf forests. That is, the ability to control the temperature and humidity of the forests along the road was larger and less variable as the distance from the road boundary to the inside of the forest increased. In this study, it is considered that the high degree of change in temperature and humidity of the forest and the surrounding area due to artificial linear development such as roads will affect the growth of trees. This results could serve as a basis for studying the quantitative scope of linear development affecting forest growth and for managing forest change caused by linear development.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1465-1483
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• 2020

Evapotranspiration is a concept that includes the evaporation from soil and the transpiration from the plant leaf. It is an essential factor for monitoring water balance, drought, crop growth, and climate change. Actual evapotranspiration (AET) corresponds to the consumption of water from the land surface and the necessary amount of water for the land surface. Because the AET is derived from multiplying the crop coefficient by the reference evapotranspiration (ET0), an accurate calculation of the ET0 is required for the AET. To date, many efforts have been made for gridded ET0 to provide multiple products now. This study presents a comparison between the ET0 products such as FAO56-PM, LDAPS, PKNU-NMSC, and MODIS to find out which one is more suitable for the local-scale hydrological and agricultural applications in Korea, where the heterogeneity of the land surface is critical. In the experiment for the period between 2016 and 2019, the daily and 8-day products were compared with the in-situ observations by KMA. The analyses according to the station, year, month, and time-series showed that the PKNU-NMSC product with a successful optimization for Korea was superior to the others, yielding stable accuracy irrespective of space and time. Also, this paper showed the intrinsic characteristics of the FAO56-PM, LDAPS, and MODIS ET0 products that could be informative for other researchers.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.2
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• pp.115-125
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• 2022

The purpose of this study was to examine the effect of packaging on quality maintenance of paprika (Capsicum annuum L. cv. Nagano RZ) stored at three different temperatures. In Korea, paprika is stored and distributed under ambient conditions. To ensure the freshness maintenance, determining optimal storage temperature is necessary. Paprika were unpacked (control) or packed with polyamide film and stored at 5℃, 10℃ and 20℃ for 35 days. Quality characteristics such as weight loss and appearance were examined. Paprika packed with polyamide film showed less quality changes compared to unpacked paprika under all the storage temperatures. The commercial properties tended to decrease rapidly during storage at 20℃ regardless of packing. The degree of weight loss was significantly lower in packed paprika compared to unpacked paprika. It was found that soluble solids, pigments, hardness, etc. were complexly affected by storage temperature and film packaging. For paprika, the storage temperature of 5℃ or 10℃ was effective in maintaining freshness; paprika packed in polyamide film packing maintained greater freshness than unpacked paprika. Our results showed that, packaging is required to preserve the freshness and to improve the marketability of paprika in the domestic market. It seems that it is necessary to continuously search for an effective packaging method.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.253-264
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• 2022

In this study, we investigated the occurrence of viral diseases in the early growth stage of soybean to establish management practices. We collected 83 soybean samples showing abnormal symptoms, approximately 3-4 weeks after seeding in the breeding field of the National Institute of Crop Science. Viruses were detected in the collected samples using reverse transcription polymerase chain reaction (RT-PCR) and metatranscriptome analysis of all those samples. The incidence of viral diseases in the field was less than 1% overall and up to 50% in certain cultivars and lines. RT-PCR and metatranscriptome analysis detected Soybean yellow mottle mosaic virus (SYMMV), Soybean mosaic virus (SMV), Soybean yellow common mosaic virus, Peanut stunt virus, and soybean geminivirus A (SGVA). Among these detected viruses, SYMMV and SMV were identified as major viruses causing infection in the early growth stage of soybean, with detection rates of 53.7% and 42.6%, respectively. Soybeans infected with SYMMV showed typical mosaic symptoms, whereas those infected with SMV showed a variety of symptoms such as mosaic, mottle, stunt, and chlorotic spots. Transmission characteristics of these viruses are variable, such that SMV is primarily transmitted by seeds, whereas SYMMV could be transmitted by insects, soil, and seeds. In this study, SGVA was detected in the early growth stage of soybean, and research on the current status and its effects on soybean after the early growth stage should be conducted.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.459-465
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• 2012

This study was conducted to obtain investigated characteristic factors which has an influence on nitrous oxide ($N_2O$) emissions related to the environment change of nitrogen application level, rainfall and temperature. It was done by the carrot cultivation at black volcanic ashes soil in the experimental field of Jeju Special Self-governing Province Agricultural Research and Extension Services from 2010 to 2011. During the carrot cultivation period, the more amount of nitrogen fertilizer applied, the more amount of $N_2O$ emissions were released. Generally $N_2O$ emissions were so deeply released to climate as that in the first and middle of cultivation with heavy rainfall released amount is high, otherwise it was released very low at the end of cultivation and drought season. $N_2O$ emissions type was considered to relate with the rainfall pattern and soil water content. We obtained the result correlated with $N_2O$ emissions, in 2010, as the soil water and soil temperature were significant to $0.5718^{**}$ ($r$) and $0.4908^{**}$ ($r$) respectively, but soil EC was not significant to 0.2704 ($r$). In 2011, soil water was significant to $0.3394^*$ ($r$), but soil temperature and soil EC were not significant to 0.2138 ($r$) and 0.2462 ($r$) respectively. Also, $NO_3$-N and soil nitrogen ($NO_3-N+NH_4-N$) were not significant to 0.0575 ($r$) and 0.0787 ($r$) respectively. During the carrot cultivation period, the average emissions factor released by the nitrogen fertilizer application for 2 years was presumed to be 0.0025 $N_2O$-N kg / N kg. This factor was 4 times than the IPCC (0.0100 $N_2O$-N kg / N kg) factor.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.197-211
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• 2015

In order to investigate optimum and marginal sowing date of foxtail millet, proso millet and sorghum in middle area (Anseong, Gyeonggi province) of korea, four levels of sowing date [(May 15(1st), June 6(2th), June 26(3th), July 13(4th)] with mulching and non-mulching were treated in this experiment. We used three crops of foxtail millet, proso millet and sorghum with four varieties of Samdachal, Samdamae, Kyeongkwan1, Hwanggeumjo in foxtail millet, Leebaekchal, Manhongchal, Hwangsilchal, Hwanggeumgijang in proso millet and Nampungchal, Hwanggeumchal, DS202, Moktaksusu in sorghum achieved from RDA. In culm length, sowing date of June 26 was the highest in all varieties of foxtail millet, proso millet and sorghum. Sowing date of May 15 showed the highest ear length in foxtail and proso millet, whereas the highest ear length was obtained from sowing date of June 26 in sorghum. In numbers of leaf, sowing date of May 15 showed the highest in all three crops of foxtail millet, proso millet and sorghum. Days from sowing to heading date were reduced in Samdamae, Kyeongkwan1 and Samdachal as sowing date was late. In Hwanggeumjo it was reduced from the sowing date from May 15 to June 26, but it was same days was taken between June 26 and July 13 sowing date. Days from sowing to heading date of four varieties in proso millet were reduced as sowing date was late. Days from sowing to heading date in sorghum were reduced as sowing date was late, whereas it was increased the $4^{th}$ sowing date of July 13. There were no significant differences in growth and yield characteristics between mulching and non-mulching in four varieties of foxtail millet, proso millet and sorghum with four varieties. The highest grain numbers per panicle, 1000 grain weight and yield per 10a were obtained from sowing date of June 26 in four varieties of foxtail millet, proso millet and sorghum. In sowing date of July 13, all varieties of foxtail millet, proso millet and sorghum were not able to be ripened because of late sowing except Hwnaggeumjo, Manhongchal and Hwanggeumgijang.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.57-73
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• 2008

Nitrate concentrations were measured up to 49 mg/L (as $NO_3$-N) and 22% of the samples exceeded drinking water standard in shallow and bedrock groundwater of the northern Nonsan area. Nitrate concentrations showed a significant difference among land use groups. To predict nitrate concentration in groundwater, multiple regression analysis was carried out using hydrogeologic parameters of soil media, topography and land use which were categorized as several groups, well depth and altitude, and field parameters of temperature, pH, DO and EC. Hydrogeologic parameters were quantified as area proportions of each category within circular buffers centering at wells. Regression was performed to all the combination of variables and the most relevant model was selected based on adjusted coefficient of determination (Adj. $R^2$). Regression using hydrogelogic parameters with varying buffer radii show highest Adj. $R^2$ at 50m and 300m for shallow and bedrock groundwater, respectively. Shallow groundwater has higher Adj. $R^2$ than bedrock groundwater indicating higher susceptibility to hydrogeologic properties of surface environment near the well. Land use and soil media was major explanatory variables for shallow and bedrock groundwater, respectively and residential area was a major variable in both shallow and bedrock groundwater. Regression involving hydrogeologic parameters and field parameters showed that EC, paddy and pH were major variables in shallow groundwater whereas DO, EC and natural area were in bedrock groundwater. Field parameters have much higher explanatory power over the hydrogeologic parameters suggesting field parameters which are routinely measured can provide important information on each well in assessment of nitrate contamination. The most relevant buffer radii can be applied to estimation of travel time of contaminants in surface environment to wells.