• Journal of Korea Water Resources Association
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• v.52 no.7
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• pp.483-492
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• 2019

An analytical model was developed to estimate the stream depletion due to cyclic groundwater pumping by extending the Hunt's analytical solution which was derived from considering the hydraulic characteristics of the aquifer and the streambed. The model was applied to analyze the long-term effects of groundwater pumping on stream depletion during irrigation season. For the case of a total of 1,500 conditions according to various aquifer and streambed hydraulic characteristics and stream-well distance, the stream depletion due to cyclic groundwater pumping for 10 years was calculated and the results were graphically represented. Especially, the maximum and average stream depletion rates were calculated and compared with the results for continuous groundwater pumping. Furthermore, considering both stream depletion and return flow rates, the limit hydraulic condition that minimizes the influence of groundwater pumping for irrigation water supply on stream depletion was suggested.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.630-646
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• 2020

In rural areas, nitrate-nitrogen (NO3-N) pollution caused by agricultural activities is a major obstacle to the use of shallow groundwater as domestic water or drinking water. In this study, the water quality characteristics of shallow groundwater in Hyogyo-ri agricultural area of Yesan-gun, Chungcheongnam-do province was studied in connection with land use and chemical composition of soil layer. The average NO3-N concentration in groundwater exceeds the domestic and agricultural standard water qualities of Korea and is caused by anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. The groundwater type mainly belongs to Ca(Na)-Cl type, unlike Ca-HCO3 type, a general type of shallow groundwater. The average NO3-N concentration (7.7 mg L-1) in groundwater in rice paddy/other (upstream, ranch, and residential) area is lower than the average concentration (22.8 mg L-1) in farm field area, due to a lower permeability in paddy area than that in farm field area. According to the trend analysis by the Mann-Kendall and Sen tests, the NO3-N concentration in the shallow groundwater shows a very weak decreasing trend with ~0.011 mg L-1yr-1 with indicating almost equilibrium state. Meanwhile, SO42- and HCO3- concentrations display annual decreasing trend by 15.48 and 13.15%, respectively. At a zone of 0 to 5 m below the surface, the average hydraulic conductivity is 1.86×10-5 cm s-1, with a greater value (1.03×10-4cm s-1) in sand layer and a smaller value (2.50×10-8 cm s-1) in silt layer.

• Journal of Mushroom
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• v.17 no.3
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• pp.113-118
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• 2019

Oyster mushrooms are an economically important crop, accounting for 35% of the total mushroom production in Korea. In this study, we developed a new cultivar of Pleurotus ostreatus, known as 'Baekseon,' which is characterized by a white pileus with a white stipe. It was bred by mating monokaryons isolated from white mutant oyster mushrooms that were naturally generated from 'Gonji-7ho' and 'Wonhyeong-1ho' at the Mushroom Research Institute, GARES, Korea in 2018. The optimum temperature for mycelial growth on potato dextrose agar medium was approximately $28-31^{\circ}C$, and the optimum temperatures for primordia formation and growth of fruit bodies on sawdust media were $22^{\circ}C$ and $20^{\circ}C$, respectively. The time required for the bottle-cultured mushrooms to complete spawn running, primordia formation, and growth of fruit bodies was 30 days, 4 days, and 4 days, respectively. The fruit bodies were bundle-shaped, the pilei were round type and white, and the stipes were white. The stipes were slender and longer than those of the control ('Miso'). In the productivity test, the yield per bottle was 185 g/1100 mL, which was 45% greater than that of the control ('Miso'). In the farm test, the yield per bottle for Farm A (Pyeongtaek) and Farm B (Yeoju) was 184 g/1100 mL and 178 g/850 mL, respectively. With regard to the physical properties of fruit bodies, the springiness, cohesiveness, gumminess, and brittleness of stipe tissue were 80%, 57%, 720 g, and 57 kg, respectively. These values were lower than those of the control ('Miso'). To test the shelf life, the fruit bodies were wrapped with antifogging film and stored at $4^{\circ}C$ for 28 days and then at room temperature for 4 days; such conditions were sufficient for maintaining edibility.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.92-92
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• 2011

수자원장기종합계획(2006)에 따르면, 우리나라는 물부족이 예상이 되고 있고, 이러한 물부족 현상은 기후변화의 영향으로 더욱 악화될 것으로 예상된다. 기후변화에 따른 물부족에 대응하기 위해서는 현행 지표수 및 지하수(Blue Water) 위주의 수자원관리와 더불어 그전에는 수자원으로 인식되지 않았던 토양수(Green Water)를 새로운 개념의 수자원으로 인식하는 것이 필요하다. 토양수는 현재 물사용량 중에서 가장 많은 비중을 차지하는 농업용수 부분에 효율적으로 활용하면, 지표수나 지하수와 같은 수자원을 대체하는 효과가 있다. 기후변화에 따른 물부족에 대응한 토양수의 효율적 활용을 위해서는, 과거 뿐아니라 미래의 지역별 시기별 토양수 공간분포특성을 분석하는 것이 선행되어야 한다. 그러므로 본 연구에서는 토양수의 분석을 통한 미래 물부족 해결에 도움이 될 새로운 수자원 관리의 기틀을 마련하기 위해 토양수 분포특성분석모델을 개발하고, 이를 활용해 과거 및 미래의 토양수의 공간분포특성을 분석한다. 토양수 분포특성분석모델은 선행 5일간의 일 강우데이터 값을 표준선행강우지표(Normalized Antecedent Precipitation Index)에 적용하여 일 단위 토양수 상태(Wet, Average, Dry condition)를 계산하는 모델이다. 과거 토양수 분석에는 인공위성 강우데이터(Tropical Rainfall Measuring Mission 3B42)를, 미래 토양수 분석을 위해서는 기상청에서 제공하는 국가표준 기후변화 시나리오(A1B)를 각각 사용하여, 과거 데이터는 27km의 격자로, 미래는 25km 격자크기로 한반도 전체의 일 단위 토양수 상태를 계산했다. 계산된 토양수 결과를 활용해 연 월별 그리고 토양수를 쓸 수 있는 시기, 즉 식물이 자라는 시기(4-9월)의 특성을 분석했다. 이를 통해 향후 기후변화에 따른 물부족 대응 토양수 수자원 활용방안에 도움이 될 것으로 예상된다.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.233-238
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• 2007

To assess pollutant loads in Nakdong river from highland agriculture in Kyungbuk province we. analyzed water qualities such as BOD, COD, T-N, T-P and SS in year 2005. BOD values in rainy period (June and July) were relatively higher than those in dry period, and those in 4 sites among 17 sites ranged from 10.71-19.25 mg/L which exceeded water criteria (8 mg/L) for agricultural use. COD values showed similar trends like BOD values. These trends might be caused by outflow of nutrients applied in agricultural lands. T-N content ranged from 0.1 to 14 mg/L. Those in lower reaches of stream were greater in those in upper stream. Compared to T-N contents during non-farming season, T-N content in farming season were higher. These phenomenon could be due to continuous input of nutrients from small watercourses. Averaged T-P content in lower stream during farming season was 0.4 mg/L, which was eight times higher than the limiting level for algae occurrence (0.05 mg/L). BOD, T-P, T-N loads from alpine agricultural practices were 12.25 $kg/km^2{\cdot}day$, 0.55 $kg/km^2{\cdot}day$ and 32.35 $kg/km^2{\cdot}day$, respectively. These values were greater than those from forestry. Therefore, Best management Practices (BMP) for alpine agricultural field are needed to reduce pollutant loads in Nakdong river.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.211-222
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• 2016

This study was conducted to investigate the physico-chemical meat quality and sensory properties of Holstein steers(n=18, 4 months old, average body weight 160kg) which were divided into 3 groups and fed 2 different energy levels of total mixed rations(TMR)(T1, TDN 74~84%; T2, TDN 77~85%) until 18, 20 or 22 months old, respectively. For loin muscles, 22-month group of T1 and 20- and 22-month groups of T2 had higher fat contents than the other groups (P<0.05). T2 had higher WHC values for 18-month groups among 3 feeding groups (P>0.05). In sensory properties, T1 had higher tenderness, flavor-likeness and overall likeness for 20-month group than the other groups (P<0.05). T2 had higher tenderness, juiciness, flavor likeness and overall likeness in 20- and 22-months groups than 18-month group (P<0.05). For top round muscles, 22-month group had higher fat contents than the other groups of T1 and T2 (P<0.05). T1 had higher in redness(a* value) and yellowness (b* value) of 22-month group (P<0.05). T2 had higher WHC values, lower WBS and CL values in 18-month group than the other groups (P<0.05). In sensory properties, T1 had higher tenderness for 18 and 20-month groups and overall likeness (P<0.05). T2 had higher tenderness in 18-month group. The results of this study showed that longer feeding of agricultural by-product TMR increased the intramuscular fat contents, however, the 18 and 20-months finishing groups were advantageous for the meat quality and sensory properties of Holstein steers.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.199-209
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• 2021

By removing the increasing trend that long-term time series average of rice yield due to technological advancement of rice variety and cultivation management, we tried to improve the rice yield estimation model which developed earlier using MODIS NDVI and meteorological data. A multiple linear regression analysis was carried out by using the NDVI derived from MYD13Q1 and weather data from 2002 to 2019. The model was improved by analyzing the increasing trend of rime-series rice yield and removing it. After detrending, the accuracy of the model was evaluated through the correlation analysis between the estimated rice yield and the yield statistics using the improved model. It was found that the rice yield predicted by the improved model from which the trend was removed showed good agreement with the annual change of yield statistics. Compared with the model before the trend removal, the correlation coefficient and the coefficient of determination were also higher. It was indicated that the trend removal method effectively corrects the rice yield estimation model.

• Korean Journal of Plant Resources
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• v.32 no.1
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• pp.38-44
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• 2019

This study was conducted to establish a domestic cultivation system of a newly introduced yam bean (Pachyrhizus erosus L.). Growth and yield were investigated in response to various cultural practices, such as seedling raising, planting distance, pinching, and flower pruning. Optimum conditions for raising of seedling were an average temperature of $22^{\circ}C$ for 30 days. Considering of the raising efficiency and the convenience of transplanting, 128 cells per tray was a suitable size. When pinching at a height of 120 cm from late July to early August, yield increased by 22% compared to no pinching. Flower pruning between late August and early September increased the number of tubers and tuber yield by 32% in comparison with no flower pruning. Yam bean seedlings planted at $50cm{\times}30cm$ spacing resulted in 30% yield increase as compared to wider spacing of $100cm{\times}30cm$. Our results thus suggested that the optimal combination of cultural practices ($50{\times}30cm$ planting distance, pinching at 120 cm height, and one time of flower pruning) increase profitability by 107%. All these results suggest high possibility of yam bean as a new income crop in Korea.

• Korean journal of applied entomology
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• v.58 no.1
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• pp.77-83
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• 2019

This study was conducted to investigate the developmental characteristics of Propylea japonica Thunberg (Coleoptera: Coccinellidae) and its consumption of Myzus persicae nymphs at 3 constant temperatures (20.0, 25.0 and $30.0^{\circ}C$; $60{\pm}5%$ relative humidity; 14 h light : 10 h dark). The longevity of adult female P. japonica under 20, 25, and $30^{\circ}C$ was 134.0, 101.0 and 55.2 days, respectively. The total fecundity was 508.6, 875.6, and 383.4 eggs during its life span, respectively. The longevity of adult male P. japonica under 20, 25, and $30^{\circ}C$ was 128.8, 97.8, and 46.5 days, respectively. Average daily consumption of adult M. persicae by 1st, 2nd, 3rd, and 4th instar P. japonica at $25^{\circ}C$ was 2.2, 7.3, 14.5, and 29.1, respectively. The average daily number of M. persicae consumed by male and female P. japonica over their lifetimes was 35.0 and 42.9, respectively. Average daily consumption of adult Aphis gossypii by 1st-4th instar P. japonica at $25^{\circ}C$ was 2.2, 7.5, 13.9, and 29.5, respectively. The average daily number of A. gossypii consumed by male and female P. japonica over their lifetimes was 37.0 and 40.8, respectively.

• Korean journal of applied entomology
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• v.60 no.1
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• pp.123-133
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• 2021

In order to use Osmia cornifrons more effectively in apples, we investigated the pollination effect and nesting activity of O. cornifrons on 'Hongro', the middle-season cultivar, and 'Fuji', the late-season cultivar. There was a significant difference in the nesting activity and pollination effect of O. cornifrons depending on the apple cultivar. The nesting activity, rate of trap nesting, and reproduction in 'Fuji' were 2.5, 1.5, and 3.8 times greater than in 'Hongro', respectively. The pollination effect according to cultivar 'Fuji' was 1.6 times greater than that of 'Hongro' in the central fruit set. In terms of the quality of fruit, the asymmetry index of 'Fuji' was 2.5 times lower than that of 'Hongro', and the number of apple seeds of 'Fuji' was 1.9 times greater than that of 'Hongro'. The main reason for this result was the air temperature. The activity of O. cornifrons was most affected by air temperature (R2 = 0.578). It is expected that the nesting activity and pollination effect are great in 'Fuji' (17.4-24.1℃) when the temperature during the blooming period is higher than that of 'Hongro' (12.5-20.2℃). Our study provides important information on stable apple production for apple cultivators, and can be used as an evidence for changes in flora and insect fauna caused by climate change.