• 한국전자파학회논문지
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• 제25권4호
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• pp.476-482
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• 2014

본 연구에서는 위성 SAR 영상을 이용한 초목층 정보 예측을 위해 옥수수의 생육에 따른 후방 산란 계수 변화를 분석한다. 이를 위하여 지상형 산란계 시스템을 이용하여 옥수수 밭의 후방 산란 계수를 측정하였으며, 지표면 정보를 입력변수로 한 1차 VRT(Vector Radiative Transfer) 기법을 이용하여 후방 산란 계수를 계산하여 측정값과 비교/분석한다. 그 결과, 생육 초기에는 옥수수보다 토양에서의 산란이 지배적이었으며, 옥수수의 밀도가 증가하면서 잎의 분포의 영향으로 입사각이 증가하면서 후방 산란 계수가 점차 상승하는 특징을 보였다. 측정 데이터와 1차 VRT 계산 오차는 평균 RMSE (Root Mean Square Error)가 VV-편파에서 1.32 dB이었고, HH-편파에서 0.99 dB이었다. 또한, 1차 VRT 계산을 통해 LAI (Leaf Area Index) 변화에 따른 작물과 토양에서의 산란 영향을 분석하였다.

• 전자공학회논문지A
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• 제32A권1호
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• pp.79-88
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• 1995

A subreflector of an offset dual reflecor antenna system mounted on satelite is analyzed by Uniform Geometrical Theory of Diffraction(UTD). In order to get the total electric field at an observation point, the reflected field and the diffracted fields obtained by UTD are summed. The reflected point and the diffracted points which have to satisfy nonlinear equations are obtained by numerical methods. The numerical results show taht diffracted fields eliminate the discontinuity of reflected fields at the shadow boundary. To show the validity of our results, the field pattern of the symmetric hyperboloidal reflector is computed and compared with S. W. Lee et al.'s results. At various obsevation angles, radiation patterns of offset ellipsoidal subreflectors offseted by a circular corn and by an elliptic corn are obrained, repectivelly.

• 한국작물학회지
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• 제50권4호
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• pp.268-275
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• 2005

Early predictions of crop yields call provide information to producers to take advantages of opportunities into market places, to assess national food security, and to provide early food shortage warning. The objectives of this study were to identify the most useful parameters for estimating yields and to compare two model selection methods for finding the 'best' model developed by multiple linear regression. This research was conducted in two 65ha corn/soybean rotation fields located in east central South Dakota. Data used to develop models were small temporal variability information (STVI: elevation, apparent electrical conductivity $(EC_a)$, slope), large temporal variability information (LTVI : inorganic N, Olsen P, soil moisture), and remote sensing information (green, red, and NIR bands and normalized difference vegetation index (NDVI), green normalized difference vegetation index (GDVI)). Second order Akaike's Information Criterion (AICc) and Stepwise multiple regression were used to develop the best-fitting equations in each system (information groups). The models with $\Delta_i\leq2$ were selected and 22 and 37 models were selected at Moody and Brookings, respectively. Based on the results, the most useful variables to estimate corn yield were different in each field. Elevation and $EC_a$ were consistently the most useful variables in both fields and most of the systems. Model selection was different in each field. Different number of variables were selected in different fields. These results might be contributed to different landscapes and management histories of the study fields. The most common variables selected by AICc and Stepwise were different. In validation, Stepwise was slightly better than AICc at Moody and at Brookings AICc was slightly better than Stepwise. Results suggest that the Alec approach can be used to identify the most useful information and select the 'best' yield models for production fields.

• 대한원격탐사학회지
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• 제22권3호
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• pp.183-197
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• 2006

Combinations of visible and near-infrared (NIR) bands in an image are widely used for estimating vegetation vigor and productivity. Using this approach to understand within-field grain crop variability could allow pre-harvest estimates of yield, and might enable mapping of yield variations without use of a combine yield monitor. The objective of this study was to estimate within-field variations in crop yield using vegetation indices derived from hyperspectral images. Hyperspectral images were acquired using an aerial sensor on multiple dates during the 2003 and 2004 cropping seasons for corn and soybean fields in central Missouri. Vegetation indices, including intensity normalized red (NR), intensity normalized green (NG), normalized difference vegetation index (NDVI), green NDVI (gNDVI), and soil-adjusted vegetation index (SAVI), were derived from the images using wavelengths from 440 nm to 850 nm, with bands selected using an iterative procedure. Accuracy of yield estimation models based on these vegetation indices was assessed by comparison with combine yield monitor data. In 2003, late-season NG provided the best estimation of both corn $(r^2\;=\;0.632)$ and soybean $(r^2\;=\;0.467)$ yields. Stepwise multiple linear regression using multiple hyperspectral bands was also used to estimate yield, and explained similar amounts of yield variation. Corn yield variability was better modeled than was soybean yield variability. Remote sensing was better able to estimate yields in the 2003 season when crop growth was limited by water availability, especially on drought-prone portions of the fields. In 2004, when timely rains during the growing season provided adequate moisture across entire fields and yield variability was less, remote sensing estimates of yield were much poorer $(r^2<0.3)$.

• 한국초지조사료학회지
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• 제13권4호
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• pp.305-311
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• 1993

우리나라에 있어서 사일리지용 옥수수(Zea mays L.)는 널리 재배가 되고 있지만 실제로 농가의 포장에서 옥수수의 사초로서 이용에 관한 연구 보고가 없는 실정이다. 따라서 경기도 여주 및 이천에서 1988년에 8개 농가 1989년에 13개 낙농가를 선정하여 사일리지용 옥수수의 재배 실태를 연구 조사하였다. 1988년에 농가생산 옥수수의 암이삭 착생주율은 75.3%. ha당 재식밀도는 75,826주, 암이삭 비율은 38.3% 그리고 수확시 건물률은 23.8%. ha당 건물수량은 12,661kg이였으며 1989년도의 암이삭 착생주율은 79.5%, ha당 재식밀도는 79.981주. 암이삭비율은 41.1%. 건물률은 20.7%. ha당 건물수량은 16.152kg 였고 흑조위축병 이병률은 11.9%였다. 그러나 농가가 제조한 옥수수 사일리지의 Flieg's score는 70∼100으로 평균은 91이 되어 품질은 우수한 편이었다. 본 연구조사 결과에 따르면 낙농가는 표준보다 훨씬 높은 재식밀도하에서 만생품종의 옥수수를 재배하고 있었으며 이러한 결과 농가 재배 옥수수의 생산성은 시험기관이 재배하는 옥수수의 생산성 보다 낮았다. 따라서 중·북부지방에서는 현재보다 더 조생품종의 옥수수를 재배하여야 하고 옥수수의 재식 밀도도 낮추어야 할 것이다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.271-271
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• 2015

The Ecuadorian coast has two different climate regions. One is humid region where the annual rainfall is above 2000 mm and rain falls in almost all months of the year, and the other is dry region where the annual rainfall can fall below 50 mm and rainfall can be very seasonal. The agriculture is frequently limited by the seasons during the year and the availability of rainfall amounts. The corn fields in Ecuador are cultivated during the rainy season, due to this reason. The weather conditions for optimum development of corn growth require a monthly average rainfall of 120 mm to 140 mm and a temperature range of $22^{\circ}C{\sim}32^{\circ}C$ for the dry region, and a monthly average rainfall of 200 mm to 400 mm and a temperature range of $25^{\circ}C{\sim}30^{\circ}C$ for the humid area. The objective of this study is to predict how the weather conditions are going to change in corn fields of the coastal region of Ecuador in the future decades. For this purpose, this study selected six General Circulation Models (GCM) including BCC-CSM1-1, IPSL-CM5A-MR, MIROC5, MIROC-ESM, MIROC-ESM-CHEM, MRIC-CGC3 with different climate scenarios of the RCP 4.5, RCP 6.0, and RCP 8.5, and applied for the period from 2011 to 2100. The climate variables information was obtained from the INAMHI (National Institute of Meteorology and Hydrology) in Ecuador for the a base line period from 1986 to 2012. The results indicates that two regions would experience significant changes in rainfall and temperature compared to the historical data. In the case of temperature, an increment of $1^{\circ}C{\sim}1.2^{\circ}C$ in 2025s, $1.6^{\circ}C{\sim}2.2^{\circ}C$ in 2055s, $2.1^{\circ}C{\sim}3.5^{\circ}C$ in 2085s were obtained from the dry region while less increment were shown from the humid region with having an increment of $1^{\circ}C$ in 2025s, $1.4^{\circ}C{\sim}1.8^{\circ}C$ in 2055s, $1.9^{\circ}C{\sim}3.2^{\circ}C$ in 2085s. Significant changes in rainfall are also projected. The rainfall projections showed an increment of 8%~11% in 2025s, 21%~33% in 2055s, and 34%~70% in 2085s for the dry region, and an increment of 2%~10%, 14%~30% and 23%~57% in 2025s, 2055s and 2085s decade respectively for humid region.

• Weed & Turfgrass Science
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• 제4권3호
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• pp.199-208
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• 2015

본 연구는 경남지역의 밭에서 발생하는 잡초의 분포현황을 조사하기 위하여 수행하였다. 보리 재배지에서는 21과 55종, 마늘 재배지 22과 56종, 양파 재배지 19과 47종, 배추 재배지 26과 68종, 감자 재배지 22과 54종, 고구마 재배지 25과 62종, 고추 재배지 29과 87종, 옥수수 재배지 28과 79종, 콩 재배지 29과 84종이 발생되었다. 작목별 우점하는 초종은 보리 재배지 뚝새풀 20.7%, 마늘 재배지 황새냉이 12.3%, 양파 재배지 좀명아주 18.7%, 배추 재배지 쇠비름 8.1%, 감자 재배지 좀명아주 13%, 고구마 재배지 바랭이 12.6%, 고추 재배지 바랭이 12.6%, 옥수수 재배지 11.3%, 콩 재배지 바랭이 13.2%로 발생되었다. 동작물 재배지에서는 뚝새풀, 황새냉이 및 좀명아주가, 하작물 재배지에서는 바랭이, 쇠비름, 깨풀이 가장 문제시 되었다. 이러한 잡초 발생 정보는 경남지역 밭잡초 관리방안 수립에 기여할 것으로 판단된다.

• 한국농공학회논문집
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• 제64권3호
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• pp.53-61
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• 2022

This study evaluated the impacts of subsurface drainage design, i.e., spacing and depth, on agricultural productivity and environmental sustainability in two tile-drained fields (Sites A and E) under a corn-soybean rotation in the Midwestern United States. A calibrated and validated Root Zone Water Quality Model (RZWQM) was used to simulate Nitrate-N (nitrogen) losses to tile drainage and crop yields of 30 tile spacing and depth scenarios over 24 years (1992-2015). Our results presented that the narrower and deeper the tile drains are placed, the greater corn yield and Nitrate-N losses, indicating that the subsurface drainage design may cause a trade-off between agricultural productivity and environmental sustainability. The simulation results also presented that up to about 255.7% and 628.0% increase in Nitrate-N losses in Sites A and E, respectively, far outweigh the rate of increase in corn yield up to about 1.1% and 1.6% from the adjustment of tile spacing and depth. Meanwhile, the crop yield and Nitrate-N losses according to the tile configuration differed depending on the field, and the soybean yield presented inconsistent simulation results, unlike the corn yield, which together demonstrate the heterogeneous characteristic of agro-environmental systems to a subsurface drainage practice. This study demonstrates the applicability of agricultural systems models in exploring agro-environmental responses to subsurface drainage practices, which can help guide the introduction and installation of tile systems into farmlands, e.g., orchards and paddy fields, in our country.

• 한국토양비료학회지
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• 제45권4호
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• pp.614-621
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• 2012

Although there is a broad dispute over genetically modified foods on safety, the worldwide adoption of transgenic crops is rapidly increasing. The objectives of this study were to identify trends in the effects of transgenic on crop yields and examine the effect of agricultural variables including crop type, biotech trait, tillage system, and yield environment on corn and soybean yield. A meta-analysis from the 34 peer-reviewed scientific literatures was conducted to compare the crop yield between transgenic crops and conventional varieties. Results showed that the yield of transgenic corn and soybean was strongly dependent on growing conditions. Transgenic hybrids had higher yield potential in the low crop yield environments such as high weeds and/or insect infestation, low soil water, and cool temperature conditions, while transgenic crops did not have yield advantages in high yield environments. The results from this study suggest that producers should consider the potential yield environmental conditions and possible yield reductions when producers choose crop hybrids in their fields.

• 한국환경농학회지
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• 제13권3호
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• pp.241-250
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• 1994

아연광산 인근지역의 농경지에 중금속의 오염정도와 옥수수의 생육에 미치는 영향을 조사하여 농작물 피해경감 대책의 기초자료로 활용하기 위하여 1993년에 경상북도 영양군 일월면 용화리 아연광산 수계지역의 토양중 중금속함량과 옥수수의 생육상황 및 토양중 중금속 함량과 식물체내 함량과의 관계에 대하여 조사 분석한 결과를 요약하면 다음과 같다. 1. 영양지역의 토양중 중금속 함량은 비오염지역인 칠곡에 비해 Zn, Cu, Pb,Cd, As 함량이 현저히 높았고 광산으로부터 거리별 토양중 중금속함량은 $2.0{\sim}2.5km$ 에서 가장 높았으나 3.0km 지점에서도 1.5Km 지점보다 높은 경향이었다. 2. 오염지역의 작물별 엽내 중금속 함량은 Zn, Cu, Pb, Cd, As 함량이 모두 콩에서 가장 높았고 다음은 옥수수, 벼의 순이었다. 3. 오염지역에서 옥수수 생육은 현저히 불량 하였고 토양중 중금속 함량도 월등히 많았다. 4. 옥수수의 부위별 중금속 함량은 토양중 함량과 같은 경향이었고 부위별로는 잎에서 가장 많았으며 원소별로는 Zn > Cu > As > Cd > Pb 순위이었으나, 각원소의 부위별 함량은 다소 차이가 있었다. 5. 토양중의 중금속함량과 옥수수 생육상황과는 전반적으로 부의 상관관계가 있었으나 조사된 원소중 Cu, Pb 함량과 옥수수의 초장, 착수고, 줄기굵기, 자수길이 및 수량과는 유의한 부의상관이 인정되었다. 6. 토양중 중금속 함량과 식물체 부위별 중금속 함량과의 관계는 대체로 정의 상관 관계를 나타냈으며, 토양중의 Pb, Cd, As 함량이 많으면 식물체 내의 Pb, Cd, As 함량이 증가되었고, 곡실중의 Pb와 As 함량은 토양중의 Cd 및 As와 유의한 정의 상관이 인정되었다.