• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.1-11
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• 2021

Soil moisture plays a critical role in hydrological processes, land-atmosphere interactions and climate variability. It can limit vegetation growth as well as infiltration of rainfall and therefore very important for agriculture sector and food protection. Recently, due to the increased damage from drought caused by climate change, there is a frequent occurrence of shortage of agricultural water, making it difficult to supply and manage stable agricultural water. Efficient water management is necessary to reduce drought damage, and soil moisture management is important in case of upland crops. In this study, soil moisture was calculated based on the water balance model, and the suitability of soil moisture data was verified through the application. The regional soil moisture was calculated based on the meteorological data collected by the meteorological station, and applied the Runs theory. We analyzed the spatiotemporal variability of soil moisture and drought impacts, and analyzed the correlation between actual drought impacts and drought damage through correlation analysis of Standardized Precipitation Index (SPI). The soil moisture steadily decreased and increased until the rainy season, while the drought size steadily increased and decreased until the rainy season. The regional magnitude of the drought was large in Gyeonggi-do and Gyeongsang-do, and in winter, severe drought occurred in areas of Gangwon-do. As a result of comparative analysis with actual drought events, it was confirmed that there is a high correlation with SPI by each time scale drought events with a correlation coefficient.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.1
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• pp.26-46
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• 2020

An irrigated-maize agroecosystem is viewed as an open thermodynamic system upon which solar radiation impresses a large gradient that moves the system away from equilibrium. Following the imperative of the second law of thermodynamics, such agroecosystem resists and reduces the externally applied gradient by using all means of this nature-human coupled system acting together as a nonequilibrium dissipative process. The ultimate purpose of our study is to test this hypothesis by examining the energetics of agroecosystem growth and development. As a first step toward this test, we employed the eddy covariance flux data from 2003 to 2014 at the AmeriFlux NE1 irrigated-maize site at Mead, Nebraska, USA, and analyzed the energetics of this agroecosystem by scrutinizing its radiation, energy and entropy exchange. Our results showed: (1) more energy capture during growing season than non-growing season, and increasing energy capture through growing season until senescence; (2) more energy flow activity within and through the system, providing greater potential for degradation; (3) higher efficiency in terms of carbon uptake and water use through growing season until senescence; and (4) the resulting energy degradation occurred at the expense of increasing net entropy accumulation within the system as well as net entropy transfer out to the surrounding environment. Under the drought conditions in 2012, the increased entropy production within the system was accompanied by the enhanced entropy transfer out of the system, resulting in insignificant net entropy change. Drought mitigation with more frequent irrigation shifted the main route of entropy transfer from sensible to latent heat fluxes, yielding the production and carbon uptake exceeding the 12-year mean values at the cost of less efficient use of water and light.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.470-470
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• 2011

환경부 하수재이용사업은 2007년도 하수도법 개정을 통해 공공하수처리시설 처리수의 재이용 의무화를 시작으로 2010년도 "물의 재이용 촉진 및 지원에 관한 법률"의 시행으로 전국적으로 사업이 확대되고 있다. 제주도 월정하수처리장은 2009년도 하수재이용사업지구로 선정이 되어 2010년도부터 농업용목적의 재이용으로 구체적인 설계와 시공이 추진되고 있는 사업지구이다. 제주도에서는 지하수보존을 위해 대체수자원 개발 방안을 시급히 마련중에 있다. 특히, 제주도 농업용수 종합계획수립(제주도, 2004)에는 하수처리수를 농업용수로 이용하기 위한 계획을 수립할 정도로 지하수 사용량을 줄이기 위한 노력을 진행중에 있으며, 그 일환으로 하수재이용사업을 지속적으로 추진하고 있다. 하수처리수의 농업용수 재이용은 사용된 물을 재이용함으로써 물과 에너지를 절약할 수 있고, 유역 또는 해양으로 배출되는 오염원을 억제하는 장점이 있는 반면에 농산물 생육에 직접 영향을 줄뿐만 아니라 주변의 수질 생태 토양 환경 및 영농인의 보건에도 영향을 주기 때문에 장기적인 관찰과 검증작업이 필요하다. 이 에 서울대와 한국농어촌공사는 안전한 농업용수 재이용기술을 개발하기 위해 장기간 현장시험을 통해 재이용 재배기술과 함께 보건환경에 미치는 영향을 검증하였고 그 개발기술을 월정사업지구에 적용하게 되었다. 월정하수처리장이 위치한 제주 동부의 월정지역은 농지면적이 밭(374ha)과 과수(12ha)등 제주도의 전형적인 농촌마을으로 주요 재배작물은 마늘과 당근, 쪽파, 콩 등으로서 농업기반시설의 미비로 영농에 어려움을 호소하고 있으며, 2006년도에 발생한 가뭄으로 그 해 평균 수학량의 30%가 감소된 바 있는 지역이다. 제주도 농업용수 종합계획수립(2004, 제주도)에서는 10년에 한발을 기준 으로 $43,000m^3$/일의 용수가 부족할 것으로 분석하였으며 최근 $35,000m^3$/day 규모의 상수도 확보사업 계획 수립하였으나 여전히 농업용수가 부족하다. 방류수의 수질은 방류수수질기준을 만족하지만 염분함량이 높아 직접 농업용으로 사용하기에는 적당하기 않고, 농업용재이용방류수 수질기준에 맞도록 재이용시스템을 통해 재처리하여 농업용수로 사용해야 한다. 제주도에서는 이미 제주 서부하수처리장 농업용수 재이용사업(이하 판포재이용사업)'이 완료되어 재이용수를 농업용수로 공급하고 있으며 향후 지속적으로 하수재이용사업이 확대될 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.439-439
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• 2012

본 연구의 목적은 색달하수처리장 방류수를 농업용수 및 조경용수 등으로 활용하기 위해 하수 처리수 재이용 사업 타당성을 분석하고자 한다. 색달하수처리장 하수재이용사업은 제주도의 지하수자원 보존과 수자원 이용의 고도화 및 방류수 재이용을 통한 갈수기 농업용수 보급으로 물자원(지하수)을 절약하고자 색달하수처리장을 대상으로 하수처리수를 농업용수로 공급하는 사업이다. 대상지역은 서귀포시 예래동에 위치하고 있으며, 중문관광단지가 소재한 마을로 제주관광의 중심지이다. 서귀포시의 총 인구는 153,797명이며 하수도 보급률은 77.7%이다('10 제주특별자치도 통계연보). 색달하수처리장이 위치한 예래동의 농지면적이 1,122ha이며, 밭(772.6)과 과수원(280.2) 등 제주도의 전형적인 농촌마을이다. 대상지역의 주요작물은 감귤, 무, 마늘, 양배추 등이 많이 재배된다. 제주도는 연평균 강수량이 1,832.6mm로 전국평균 1,274 mm 보다 많은 편이며, 월별 강수량은 6~8월까지 3개월 동안 연 강우량의 44%정도가 내려 여름 장마철에 집중되는 것으로 나타났다. 대상지구의 필요수량은 농업생산정비 계획설계기준에 제시된 방법을 이용하여 산정하였다. 지구내 재이용수를 공급할 관정 4개소의 총 설계 채수량은 $2,916m^3/day$, 급수면적은 125.0ha이며, 10년한발(가뭄)시 안정적인 농업용수 공급을 위하여 $4,964m^3/day$(농업용수 $3,834m^3/day$, 조경용수 $1,130m^3/day$)이 필요하다. 하수처리수 재이용을 위한 처리시설의 연간 유지관리비는 인건비, 전력비, 시설물 내구연한을 고려하여 적용 하였으며, 상수도 생산비 절감 비용과 하수재이용수 생산단가를 통한 단위 편익을 산정하면 401.5원/$m^3$ 이다. 연차별 수익으로 산정하여 비용 편익 비율(B/C Ratio)을 나타내면 1.22로 나타났다. 본 연구의 결과로부터, 대상지구의 수자원여건, 입지여건, 장래 수요, 등을 고려할 때, 제주 색달 하수처리장의 하수처리수의 농업용수재이용 사업은 타당성이 매우 높다고 할 수 있다. 그리고 특히 이 지역은 관광단지의 조경용수 수요(중문골프장 등)가 있어 용수의 유료공급이 가능하고 이를 유지관리비로 충당할 수 있어 타지역에 비해 사업의 경제성과 환경보전성이 매우 크다.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.549-556
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• 2017

The purpose of this study was to investigate the change of spatial distribution of Korean fir (Abies koreana E. H. Wilson) in Mt. Hallasan for the past 10 years. We examined the distribution and crown density between 2006 and 2015 and analyzed the elevation, direction, and regional characteristics. The total area of Korean fir was 626.0ha in 2015, which declined by 112.3ha accounting for 15.2% for the past 10 years compared to 738.3ha in 2006. For the past 10 years, the area of moderately dense Korean fir with the crown density of 41% to 70% decreased by 72.6ha while the area of dense Korean fir with the crown density of 71% or more deceased by 21.3ha. The area with an elevation between 1,510m and 1,600m showed the largest change, accounting for 32.6% of the total declining area. Regarding the distribution by the direction, the area in the southeastern direction decreased by 23.4ha while the area in the southeast and northeast centered on the eastern direction decreased by 62.3ha, which accounted for 55.5% of the total area. Regarding the change of the distribution of Korean fir forest area by the region, the decrease of the area from the Jindallaebat to the top of the mountain was the largest at 84.6ha, or 71.8% of the total decreased area. The Yeongshil Trail area decreased by 25.3ha or 21.5% of the total while the Keundurewat area decreased by 8.0ha or 6.8%. On the contrary, the Bangaeoreum area increased by 5.6ha. The results indicate the large decrease of area of Korean fir forest centered on a particular location of Mt. Hallasan. Considering the changes according to the elevation, direction, and regional characteristics, it can be attributed to increasing frequency of abnormal climates such as typhoons and droughts.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.73-78
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• 2018

BACKGROUND: Soil salinity of reclaimed tidal land in Korea is highly important factor. High salinity is harmful to crop productivity. Jerusalem artichoke (Helianthus tuberosus L.) is known to be salt-tolerant and has high adaptability to diverse pedo-climatic conditions. The objective of this study was to assess the changes of soil properties and crop productivity according to salt concentration in the reclaimed tidal lands. METHODS AND RESULTS: Experimental sites were selected at Saemangeum ($35^{\circ}46^{\prime}N$, $126^{\circ}37^{\prime}E$) reclaimed tidal land, and their dominant soil series were Munpo (coarse loamy, mixed, non-acid, mesic, typic Fluvaquents). H. tuberosus L were collected from 12 locations across Korea. Tubers were planted at $75{\times}25cm$ with EC 2 to $7dS\;m^{-1}$. Soil samples were periodically collected from both 0~20 cm and 20~40 cm depths of each site. Soil salinity and soil moisture contents were varied depending on weather conditions. Soil electrical conductivity varied from 1.0 to $5.9dS\;m^{-1}$, and soil moisture contents varied from 9.2 to 28.7%. The white-colored tubers of H. tuberosus L. collected from 'Yeongwol-gun' exhibited the highest height (207 cm), followed by the white-colored tubers of H. tuberosus L. collected from 'Iksan-si'(202 cm). The white-colored tubers of H. tuberosus L. collected from 'GyeongJu-si' showed the highest yield (549 kg/10a). The purple-colored tubers of H. tuberosus L. collected from 'Yeongwol-gun' showed the highest yield (615 kg/10a). CONCLUSION: Our results indicate that the plant height and tuber yield did not appear to be correlated. Considering yield and inulin content, the GyeongJu-si seemed to be suitable as the white-colored tubers of H. tuberosus L. and the Yeongwol-gun seemed to be suitable as the purple-colored tubers of H. tuberosus L. in the reclaimed tidal lands. However, it is necessary to consider the relationship between the inulin content and the yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.72-78
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• 2020

In this study, miscanthus with C/N ratio of 224 were applied to the soil and treated with 0 (control), 10 tons and 20 tons·ha^-1 to improve the soil and promote crop growth. As a result, soil organic matter content increased from 11.0 g·kg^-1 before the test to 16.3 after 3 years. Soil cation exchangeable capacity increased to 15.3 cmol_c·kg^-1 after 3 years. In the sweet sorghum, stem was the most thickest at 20 tons·ha^-1 application of miscanthus and the highest juice amount per plant was 60 ml. The yield index multiplied by the soluble solids content of juice and juice amount was the highest at 1,913 for 10 tons application and 1,851, 1,839 for 20 tons, control respectively. Number of sweetpotato storage root were 2,9 in 20-tons application plot, the same as control, and 10-tons application plot was 3.6, the most. Two-year average yields of 20 tons plot and control were low at 2,579 kg/10a and 2,708 respectively, and 10 tons plot was the highest at 3,289. For onions, the biomass application did not effect the yield. but onion plant and leaf length were longer in 20 tons plot than in control or 10 tons. The yield of garlic was 2,630~2,901 kg/10a and there was no effect of miscanthus application. Plot of 10 tons application were the longest in plant and leaf length, and the number of scale was 8.2-8.3 per in bulb, and 8.9 tons·ha^-1 in control. Therefore, it was confirmed the possibility that miscanthus biomass application of about 10 tons·ha^-1 could improve the soil condition and promote crops growth and yield.