• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.104-111
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• 2000

The study war carried out to evaluate the characteristics of inorganic phosphate factions in soil mixed with paper mill sludge compost(PMSC). The experiments were conducted by an incubation test. For the incubation test, application rates of PMSC to soil were 0, 2, 8, and 16%. Water content of the samples mixed with PMSC were adjusted to 10% and 15% and incubating temperatures of the samples were kept at $4^{\circ}C$ and $30^{\circ}C$, respectively. The results can be concluded as follows; pH increased depending on the higher rates of PMSC application to the soil during the incubation tests, because calcium content was $4.9cmol_c/kg$ and contents of nutrients were high. When the application rates of PMSC were increased Saloid-P and Fe-P decreased, while Al-P and Ca-P in soil increased during the incubation tests.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.174-179
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• 2007

Although the relationship between fermentation and factors such as soil water, redox potential, rootstocks and climatic conditions has been reported, its mechanism of fermentation is still not clear. Transpirations of leaf and fruit at different climatic conditions, influence of soil water potential and atmospheric vapor pressure deficit (VPD) on fermentation were evaluated. Transpiration rate decreased with decreasing soil temperature and soil water potential. Low VPD conditions which occurred during low air temperature and high humidity also decreased transipration rate. These data exhibit that fruit water balance affected by various factors relate to transpiration. Our results also indicate that high hydraulic conductance of root, high soil water potential and low VPD condition exert a significant effect on fermention of oriental melon and so called "water filled fruit".

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.39-42
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• 2022

쌀을 주식으로 하는 우리나라에서, 쌀의 가격에 영향을 미치는 변수를 찾는 것은 유의미한 연구이다. 본 논문에서는 쌀 가격을 예측하는 모델에 포함되는 여러 변수 가운데 상대적인 중요도가 낮은 변수를 제거하고 유의미한 변수만을 남기고자 한다. 이를 위해 기상, 수확량, 소비자물가의 10년 치 정보를 수집하고 정제한 결과 총 2460일, 7개 지역에서 추출된 17,219개의 데이터를 이용하였다. 모델 평가 결과, 모든 변수를 포함한 모델의 RMSE는 166.0759, 단계적으로 계수가 작은 9개의 변수를 제거한 최종적인 모델의 RMSE는 168.5576으로 유의미한 차이를 보이지 않았다. 최종적으로 남은 변수는 총 10개로 평균 기온, 평균 풍속, 합계 일사, 평균 지면 온도, 0.5M 평균 습도, 4.0M 평균 습도, 10CM 일 토양 수분, 30CM 일 토양 수분, 50CM 일 토양 수분, 전년도 생산량이 포함된다.

• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1293-1307
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• 2012

This study is to evaluate the RHESSys (Regional Hydro-Ecological Simulation System) simulated streamflow (Q), evapotranspiration (ET), soil moisture (SM), gross primary productivity (GPP) and photosynthetic productivity (PSNnet) with the measured data. The RHESSys is a hydro-ecological model designed to simulate integrated water, carbon, and nutrient cycling and transport over spatially variable terrain. A 8.5 $km^2$ Seolma-cheon catchment located in the northwest of South Korea was adopted. The catchment covers 90.0% forest and the dominant soil is sandy loam. The model was calibrated with 2 years (2007-2008) daily Q at the watershed outlet and MODIS (Moderate Resolution Imaging Spectroradiometer) GPP, PSNnet and 3 year (2007～2009) daily ET data measured at flux tower using the eddy-covariance technique. The coefficient of determination ($R^2$) and the Nash-Sutcliffe model efficiency (ME) for Q were 0.74 and 0.63, and the average $R^2$ for ET and GPP were 0.54 and 0.93 respectively. The model was validated with 1 year (2009) Q and GPP. The $R^2$ and the ME for Q were 0.92 and 0.84, the $R^2$ for GPP were 0.93.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.93-100
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• 2011

Maintenance of adequate soil water potential during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing the adverse effects of water stress on crop growth and development and the leaching of water below the root zone which can have adverse environmental effects. The objective of this study was to evaluate the feasibility of using a portable irrigation controller with an Watermark sensor for the cultivation of drip-irrigated vegetable crops in a greenhouse. The control capability of the irrigation controller for a soil water potential of -20 kPa was evaluated under summer conditions by cultivating 45-day-old tomato plants grown in three differently textured soils (sandy loam, loam, and loamy sands). Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30 cm depths. Even though a repeatable cycling of soil water potential occurred for the potential treatment, the lower limit of the Watermark (about 0 kPa) obtained in this study presented a limitation of using the Watermark sensor for optimal irrigation of tomato plants where -20 kPa was used as a point for triggering irrigations. This problem might be related to the slow response time and inadequate soil-sensor interface of the Watermark sensor as compared to a porous and ceramic cup-based tensiometer with a sensitive pressure transducer. In addition, the irrigation time of 50 to 60 min at each of the irrigation operation gave a rapid drop of the potential to zero, resulting in over irrigation of tomatoes. There were differences in water content among the three different soil types under the variable rate irrigation, showing a range of water contents of 16 to 24%, 17 to 28%, and 24 to 32% for loamy sand, sandy loam, and loam soils, respectively. The greatest rate increase in water content was observed in the top of 10 cm depth of sandy loam soil within almost 60 min from the start of irrigation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.451-458
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• 2012

This study was conducted to investigate the characteristic factors which have been influenced on nitrous oxide ($N_2O$) emissions related to the environment change of nitrogen application level, rainfall and temperature during the soybean cultivation at black volcanic ash soil from 2010 to 2011. During the soybean cultivation, the more amount of nitrogen fertilizer applied, $N_2O$ emissions amounts were released much. $N_2O$ emissions with the cultivation time were released much at the first and middle of cultivation with heavy rainfall, but it was released very low until the end of cultivation and drought season. $N_2O$ emissions mainly were influenced by the rainfall and soil water content. The correlation ($r$) with $N_2O$ emissions, soil water, soil temperature and soil EC in 2010 were very significant at $0.4591^{**}$, $0.6312^{**}$ and $0.3691^{**}$ respectively. In 2011, soil water was very significant at $0.4821^{**}$, but soil temperature and soil EC were not significant at 0.1646 and 0.1543 respectively. Also, $NO_3$-N and soil nitrogen ($NO_3-N+NO_4-N$) were very significant at $0.6902^{**}$ and $0.6277^*$ respectively, but $NO_4$-N was not significant at 0.1775. During the soybean cultivation, the average emissions factor of 2 years released by the nitrogen fertilizer application was presumed to be 0.0202 ($N_2O$-N kg $N^{-1}\;kg^{-1}$). This factor was higher about 2.8 and 2 times than the Japan's (0.0073 $N_2O$-N kg $N^{-1}\;kg^{-1}$) value and 2006 IPCC guideline default value (0.0100 $N_2O$-N kg $N^{-1}\;kg^{-1}$) respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.544-550
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• 2012

This study was conducted to investigate the characteristic factors which have been influenced on nitrous oxide ($N_2O$) emissions related to the environment change of nitrogen application level, rainfall and temperature during the potato cultivation at black volcanic ash soil from 2010 to 2011. During the potato cultivation, the more amount of nitrogen fertilizer applied, $N_2O$ emissions amounts were released much. $N_2O$ emissions with the cultivation time were released much at the first and middle of cultivation with heavy rainfall, but it was released very low until the end of cultivation and drought season. $N_2O$ emissions mainly were influenced by the rainfall and soil water content. The correlation (r) with $N_2O$ emissions, soil wate, soil temperature in 2010 were very significant at $0.6251^{**}$ and $0.6082^{**}$ respectively, but soil EC was not significant to 0.10824. In 2011, soil temperature was very significant at $0.4879^{**}$, but soil water and soil EC were not significant at 0.0468 and 0.0400 respectively. Also, $NH_4$-N was very significant at $0.7476^{**}$, but $NO_3$-N and soil nitrogen ($NO_3-N+NH_4-N$) were not significant at 0.0843 and 0.1797, respectively. During the potato cultivation period, the average emissions factor of 2 years released by the nitrogen fertilizer application was presumed to be 0.0040 ($N_2O-N\;kg\;N^{-1}\;kg^{-1}$). This factor was lower about 2.5 times than the IPCC guideline default value (0.0100 $N_2O-N\;kg\;N^{-1}\;kg^{-1}$).

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.300-300
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• 2009

화학비료를 이용할 수 없는 유기농업에서의 양분관리를 위해서 녹비, 퇴비, 유박 등을 주 원료로 하는 유기질비료 등 다양한 유기물이 농경지에 투입되고 있다. 그러나 다양한 성분 및 탄소/질소비로 이루어진 유기물은 토양 중에서 분해되는 속도가 다르고, 토양수분함량, 통기성, 온도 등과 같은 토양조건에 따라서도 분해속도가 크게 차이가 난다. 본 실험에서는 유기농업에서 시비원으로 자주 이용하는 퇴비, 유박비료, 녹비조건의 알팔파 등을 이용하여 무기화율 및 양분이용률을 화학비료와 비교하였다. 농경지 투입시 유기물은 질소양분양(21kg N/10a)을 동일하게 투입하였으며 화학비료는 기비(전체량의 1/3)만을 투입하였는데 알팔파, 유박비료의 경우 노지조건에서 토양처리 후 1달 내에 가장 높은 무기화율을 보였으며 수분조건이 제한된 무기화통내에서의 무기화도 2개월 내에 대부분 이루어지는 것으로 나타났다. 수딘그라스를 2개월 재배한 결과 화학비료 질소 양분이용율은 70%, 탄질비가 낮은 유박 및 알팔파는 40%내외, 탄질비가 높고 분해가 어려운 가축분 왕겨퇴비는 10%에 불과했다. 즉 화학비료 대비 유기물 양분(질소)의 비효화 율은 알팔파는 60%, 유박비료는 54%, 퇴비는 14% 였다. 또한 화학비료(100%) 대비 인산 이용률(유박: 296%, 알팔파: 660%, 퇴비: 36%로, 인산의 이용율이 높은 것은 유기물로 투입된 인산의 량이 화학비료보다 낮아 상대적으로 유기물질에 의한 작물의 인산이용율이 높고, 화학비료는 토양중 고정화가 작물생육 초기에 일어나는데 비하여 유기물질은 서서히 분해되면서 작물에 흡수되어 인산이용율이 높은 것으로 추정된다. 수단그라스 1차수확 후 포장침수로 인한 생육불량으로 전 생육 과정을 통한 양분흡수율은 측정할 수 없었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.525-525
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• 2015

국립기상과학원은 국가 물관리를 효율적으로 지원하기 위하여 TOPLATS(TOPmodel based Land-Atmosphere Transfer Scheme) 지면모델 기반을 활용한 전국 수문기상 분석 및 예측정보 생산체계를 구축하였다. TOPLATS 지면모델에서는 토양, 식생 등을 표현하기 위한 다양한 매개변수들이 사용되고 있으며, 그 중에서도 토양 속성과 관련 매개변수들은 토양수분, 증발산 등의 수문기상요소 생산에 큰 영향을 미치고 있어 현실적인 토양 특성에 대한 고려가 요구된다. 본 연구는 국립농업과학원의 토양도 정보를 이용하여 TOPLATS 지면모델에서 요구되는 토양 속성 및 관련 매개변수를 산정하고 이를 모델에 적용하고자 하였다. TOPLATS 모델에 사용되는 토양 매개변수는 총 22개 이며, 본 연구에서는 국립농업과학원에서 제공한 총 405개의 토양통에 대한 매개변수를 각각 산정하였다. TOPLATS 모델을 강제하기 위한 기상자료는 동네예보 분석자료, KLAPS(Korea Local Analysis and Prediction System) 분석자료, 입사 단 장파 복사량은 ASOS 관측자료를 기반으로 한 5km 해상도의 남한 격자자료이며, 2010~2013년 기간의 토양수분, 증발산량에 대한 검증 연구를 수행하였다. 본 연구의 결과는 기존의 11개 토양속성정보로 산출된 결과와 비교 분석하여 추후 제시할 예정이며, 본 연구에서 산출된 국내 토양 특성을 반영한 고해상도 수문기상정보는 향후 홍수 예측 및 가뭄 평가에 활용 할 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.355-355
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• 2019

본 연구에서는 물리적 매개변수 기반의 물 순환 해석 모형인 CAT(Catchment hydrologic cycle Assessment Tool)을 이용하여 보령댐 유역 상류에 위치한 삼산저수지의 저류량을 분석하였다. 연구기간은 2012~2017년이며 2015년 발생한 가뭄 대책의 일환으로 2016년 이후 금강과 보령댐을 잇는 도수로를 설치하여 유역내로 외부유입량이 유입되었다. 이에 본 연구에서는 보다 정확한 저류량 산정을 위해 모의 기간을 2012~2015년 및 2016~2017년으로 나누어 연구를 수행하였다. 매개변수 보정에 앞서 CAT에서 제공하는 세 가지 침투해석방법인 Rainfall Excess, Green&Ampt, Horton 방법을 모두 적용하여 모의하였으며 그 결과 Rainfall Excess 침투방법을 적용했을 때의 모의 정확도가 비교적 높게 나타나는 것을 확인할 수 있었다. 이에 본 연구에서는 Rainfall Excess 침투방법의 주요 토양 관련 매개변수인 토양수분율(${\theta}s$), 연직방향 투수계수(ks) 및 사면방향 투수계수(ksi)를 대상으로 전역최적화기법(SCEUA-P)을 이용한 보정을 수행하였으며 보정 전 후의 모의 저류량과 관측 저류량을 연도별로 비교 및 분석하였다.