• Journal of Biosystems Engineering
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• 제40권4호
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• pp.305-313
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• 2015

Purpose: This study was performed to predict the fatigue life of a crank-type rotavator operated in domestic soil conditions using Recurdyn$^{(R)}$, a dynamic analysis program. Methods: Torque on the PTO shaft was measured using experiments conducted on the uplands and paddy fields in Korea. On the basis of the experimental and analytical results, the fatigue life of the crank-type rotavator was predicted by constructing an S-N curve according to the GL (Germanischer Lloyd Wind Energie GmbH) guideline. Results: The torques experienced by the PTO shaft in the paddy soil and the uplands were in the range of 472~797 N m and 313~430 N m, respectively, for every condition. In case of load condition, the peak torques (846 N m, 770 N m) were applied for severe conditions, resulting in a maximum (von Mises) stress of 75 MPa at the crank arm. The fatigue life of the crank-type rotavator was predicted to be 1,167 h that satisfies the target value of 1,110 h, by substituting the analysis results into an S-N curve of crank arm. Conclusions: The fatigue life of the crank-type rotavator was within the target life for the studied soil conditions; however, further field experiments for various soil conditions would be required to verify the prediction results.

• 한국환경과학회지
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• 제24권4호
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• pp.515-524
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• 2015

The estimation of groundwater usage in Jeju island is important to understand hydrologic cycle system and to plan management of water resource because large amounts of groundwater have been used for agricultural and domestic purpose. The model has been developed to estimate agricultural groundwater usage for garlic at uplands and citrus at orchards raising outdoors using the soil water balance model from FAO 56, respectively. The total amount of water supplied for the crop evapotranspiration and the multipurpose function such as sprout promotion can be simulated by the model. However, due to the discrepancy of water use in initial stage between calculated and observed, the model was calibrated and verified using actual groundwater usage monitoring data for 3.5 years (2011.6 to 2014.12) at three uplands for garlic and three orchards for citrus. Consequently, it would be concluded that the model simulated efficiently actual water usage in that root mean square (RMS) and normalized RMS of the validation stage were less than 8.99 mm and 2.43%, respectively, in two different conditions.

• 한국잡초학회지
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• 제4권1호
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• pp.4-10
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• 1984

전북지역(全北地域)의 밭 잡초식생변화(雜草植生變化)를, 재배작물별(栽培作物別) 및 경지형태별(耕地形態別) 조사(調査)하였다. 1. 전북지역(全北地域) 밭에 발생하는 잡초(雜草)는 18과(科) 44종(種)으로, 일년초(一年草) 22종(種), 월년초(越年草) 11종(種) 및 다년초(多年草) 9종(種)으로 구성(構成)되어 있었다. 발생빈도별(發生頻度別)로 보면, 바랭이가 67.2%로 가장 높았으며, 다음으로 쇠비름, 명아주, 망초의 순위(順位)였다. 3. 조사지역(調査地域)의 약(約) 60%에 해당(該當)되는 지역(地域)의 잡초식생(雜草植生)이 Simpson 지수(指數) 0.20에서 0.50사이를 나타내었다. 4. 밭에서의 Simpson 지수(指數)는 계절적(季節的)으로 변화(變化)되어, 6월(月)8일(日)의 0.65가 11월(月)10일(日)에 0.15로 감소(減少)되어 잡초식생(雜草植生)이 다양화(多樣化)되고 있음을 나타내었다. 5. 경지형태별(耕地形態別)로 보면 답이작전(沓裏作田)에서는 독새풀과 여뀌, 숙전(熟田)에서는 바랭이와 쇠비름이 우점종(優占種)이었고 야산개간지(野山開墾地)에서는 쑥을 비롯한 다양(多樣)한 초종(草種)들이 고루 발생(發生)하고 있었다. 6. 콩을 비롯한 5개 작물포(作物圃)의 Simpson 지수(指數)는 평균(平均) 0.4로써 작물(作物)의 종류(種類)에 관계없이 쇠비름과 바랭이가 우점종(優占種)이었고, 여뀌, 명아주, 쇠비름, 망초 등이 차우점종(次優占種)으로 나타났다.

• 한국수자원학회논문집
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• 제47권10호
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• pp.973-983
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• 2014

본 연구는 밭경지 현장실험을 통해 다양한 초생대 초종을 적용하여 밭의 비점오염저감효과 분석 및 초생대에 적용 가능한 적합한 초종을 선정하고자 하였다. 경북 군위군에 위치한 면적 $1,500m^2$, 경사 5%의 밭경지를 선정하여 시험포를 조성하였으며, 시험포내에는 대조구 1개와 초생대 처리구 6개로 구성된 총 7개의 시험구를 조성하였다. 츄파, 피, 바랭이, 잔디, 톨페스큐, 켄터키블루그라스를 포함하는 6개의 초종을 선정하여 초생대 실험을 수행하였다. 현장실험 결과 대조구 대비 초생대의 유출저감효과는 6.1~77.8%였으며, 비점오염저감효과는 TS의 경우 15.6~90.3%, T-P의 경우 49.9~96.6%, T-N의 경우 6.7~91.1%를 나타내었다. 전체 오염인자 중에 초생대로 인해 전반적으로 높은 비점오염저감 효과를 나타낸 것은 TS, T-P, T-N, SS인 반면, BOD, TOC와 $NO_3^-$는 낮은 저감효과를 보였다. 비점오염저감 및 유지관리측면에서 가장 유리한 초생대 초종은 잔디로 평가되었다. 본 연구결과를 통해 우리나라 농촌지역 밭 비점오염저감을 위한 관리기법으로 초생대가 효과적으로 활용가능하리라 사료되며, 보다 장기적이고 다각적인 현장실험을 통해 초생대 현장적용을 위한 설계 지침서 개발이 요구된다.

• 한국토양비료학회지
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• 제12권1호
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• pp.25-34
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• 1979

'77/'78맥작기간 영남지방(嶺南地方)에서 발생(發生)한 맥류불임현상의 원인(原因)을 구명(究明)하기 위하여 이것과 관련(關聯)되는 몇가지 환경요인(環境要因)을 조사(調査)해 본 결과(結果). 1. 기상상태(氣象狀態)는 특(特)히 보리의 주요생육시기(主要生育時期)에 해당(該當)되는 감수분열기(減數分裂期) 및 출수기경(出穗期頃)에 심(甚)한 조발(早魃)과 저온(低溫)이 내습(來襲)하였다. 2. 토양수분함량(土壤水分含量)은 전작(田作)보다 답리작(畓裏作)에서, 표토(表土)보다 심토(深土)에서 많았으며, 사토(砂土)보다는 식토(埴土)가 많았고, 남향(南向)보다 북향(北向)으로 된 경사지(傾斜地)에서 많은 경향(傾向)이었다. 3. 입지조건(立地條件)에 따른 보리이삭의 불임율(不稔率)은 답리(畓裏)이 전작(田作)보다 낮았고, 비상지(扉狀地) 및 평탄지(平坦地)는 구릉지(丘陵地), 산록경사지(山麓傾斜地)보다 낮았고, 남향(南向)보다 북향(北向)으로 된 경사지(傾斜地)가 낮은 편(便)이었다. 4. 경지(耕地)의 토성별(土性別) 불임율(不稔率)은 사토(砂土)에서 높았고, 식토(埴土)에서 낮았으며 작토호(作土戶) 및 유효토심이 얕을수록 높은 경향(傾向)이었다. 5. 답리작(畓裏作), 전작(田作) 다같이 표토(表土) 및 심토(深土)의 토양수분함량(土壤水分含量)과 보리이삭의 불임율(不稔率)과는 부(負)의 상관관계(相關關係)가 인정(認定)되었다. 6. 따라서 맥수 생식생장기간(生殖生長期間)의 주요시기(主要時期)에 수분부족(水分不足)은 수(穗)의 불임발생(不稔發生)의 주요원인(主要原因)으로 인정(認定)되었고, 이와함께 극심(極甚)한 저온(低溫)은 불임발생(不稔發生)을 더욱 조장(助長)하는 것으로 생각된다.

• 대한환경공학회지
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• 제32권11호
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• pp.1024-1029
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• 2010

본 연구에서는 경사도 20%의 강원도 경작지 실험포장(가로 3 m${\times}$세로 18 m)을 대상으로 자연강우 조건하에서 폴리머 기반 토양개량제인 polyacrylamide (PAM) 및 바이오폴리머의 처리가 토양유실 및 작물의 생장에 미치는 영향을 평가하였다. 40 kg/ha PAM 및 바이오폴리머 처리시 토양입단 안정도는 대조구에 비해 최대 11% 증가하였다. 생육조사 결과 폴리머 처리에 따라 무(Raphanus sativus)의 엽장은 증가하였으나 수확량의 경우 유의적인 차이를 나타내지는 않았다(P>0.05). 토양유실의 경우 폴리머 기반 토양개량제 처리시 토양유실량이 최대 41% 감소하였으나 유거수량에는 유의적인 차이가 없었다. 또한 토양유실량은 강우강도의 증가에 따라 대수관계($R^2=0.85$)로 증가함을 확인하였다. 이상의 결과로부터 피복이 완전치 못한 경사지 경작지에 대한 폴리머 기반 토양개량제 시용은 토양유실 저감에 효과적이며 작물생육 촉진 및 토양질 향상에도 기여할 수 있을 것으로 판단된다.

• 동굴
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• 제36권37호
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• pp.103-113
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• 1994

Slope soil formation and its attributes in southwestern Wisconsin are potentially important due to its origin, landscape position and karstic backgrounds (Oh, 1990). Since French explorers and missionaries reached in southwestern Wisconsin in the 1830's, the loess mantled karst upland surfaces, consisted of forests: timberland, oak openings, and prairie, had been cultivated. At present, nearly 90% of the ridge land is in farms. Karst soils are usually reddish clayey features (Oh and Day, 1989).(omitted)

• 한국농공학회논문집
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• 제57권2호
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• pp.75-83
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• 2015

This study was aimed to estimate the total application cost and utilization of Turf grass VFS application through the field experiment. The experimental plots were constructed in an upland field of Iksan city within the Saemangeum watershed. Turf grass was transplanted at the down-slope edge of the pollution source area in each of the treated plots. Three rainfall events were monitored during the experiment period, and the rainfall-runoff relationships and NPS pollution reduction effects of the VFS systems were assessed. As results, the reduction ratio of runoff volume ranged 14.1~64.0 %, while the NPS pollution reduction ratio ranged 9.8~73.9 % for SS, 24.0~84.2 % for T-N, 31.6~80.9 % for T-P respectively. The total cost of VFS application was estimated by considering purchase cost of Turf grass sods and construction and maintenance costs of VFS system as well as the loss caused by giving up crop cultivation for the area needed to construct the VFS. The total cost of the VFS was estimated to be approximately \3,379,000/ha/year for the first year of application, and this cost could be decreased to \1,899,000/ha/year from the second year as the construction cost of VFS could no longer need to be counted afterwards. Apart from the NPS pollution reduction effects, the possible utilization of VFS was examined by detaching Turf grass within 40 % of VFS area for sale during spring time when the VFS systems fully covered. The benefit of selling the detached Turf grass sods was estimated as \1,260,000/ha/year, and also found that the VFS area successfully recovered by the time of the summer period. This benefit could attract farmers to adopt the VFS technique to manage agricultural NPS pollution.

• 한국환경농학회지
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• 제37권3호
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• pp.151-159
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• 2018

BACKGROUND: In this review paper, the effects of surface cover (SCV), vegetative filter strip (VFS), and vegetated ridge (VRD) on the pollutant runoff from steep-sloping uplands were analyzed to compare the pollutant reduction efficiency in runoff ($PRE_{runoff}$) of the practices and to investigate how slope and rainfall parameters affect the $PRE_{runoff}$. METHODS AND RESULTS: The $PRE_{runoff}$ of SCV, VFS, and VRD for pollutants including suspended solids and biological oxygen demand was compared by analysis of variance. The effect of slope and rainfall parameters on the $PRE_{runoff}$ was explored by either mean comparison or regression analysis. It was found that the $PRE_{runoff}$ differs with the practices due to different pollutant reduction mechanisms of the practices. Though the $PRE_{runoff}$ was likely to be affected by site condition such as slope and rainfall (amount and intensity), more comprehensive understanding was not possible due to the limited data set. CONCLUSION: The $PRE_{runoff}$ of SCV, VFS, and VRD differed due to the distinctive mechanisms of pollutant removal of the practices. It is necessary to accumulate experimental data across a variety of gradient of slope and rainfall for comprehensive understanding of the effects of the practices on pollutant runoff from steep-sloping uplands.

• 한국농공학회논문집
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• 제63권4호
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• pp.55-64
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• 2021

The expansion of upland crop cultivation in rice paddy fields is recommended by the Korean government to solve the problem of falling rice price and reduction of rice farmer's income due to oversupply of rice. However, water use efficiency is significantly influenced by the land use change from paddy field to upland. Therefore, this study aimed to evaluate the water budget of soybean grown in using APEX (Agricultural Policy and Environmental eXtender) model. The amount of runoff was measured in a test bed located in Iksan, Jeollabu-do and used to calibrate and validate the simulated runoff by APEX model. From 2019 to 2020, the water budget of soybean grown in uplands were estimated and compared with the one grown in paddy fields. The calibration result of AP EX model for runoff showed that R² (Coefficient of determination) and NSE (Nash-Sutcliffe efficiency) were 0.90 and 0.89, respectively. In addition, the validated results of R² and NSE were 0.81 and 0.62, respectively. The comparative study of each component in water budget showed that the amounts of evapotranspiration and percolation estimated by APEX model were 549.1 mm and 375.8mm, respectively. The direct runoff amount from upland was 390.1 mm, which was less than that from paddy fields. The average amount of irrigation water was 28.7 mm, which was very small compared to the one from paddy fields.