• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1166-1175
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• 1993

The objective of this study is to measure contra-retractive adhesion and lift resistance acting on the rim section of a circular wheel for analyses of their effects on the dynamic load. A circular iron wheel was used for experiments. A part of the wheel rim was cut off, and transducers which can measure normal and tangential forces were installed in this section. Experiments were conducted on a laboratory soil bin which was filled with clayey soil under wet and dry conditions. The mechanism of generating contra -retractive adhesion on a circular wheel were analyzed by the experiments and motion analyses of the wheel. Effects of lift resistance on dynamic load were analyzed by measured forces under wet soil conditions in comparison in comparison with those under dry conditions. The showed that a part of the lift resistance were transferred to the dynamic load. These results may become basic data and ideas for analyses of tractor dynamic under wet soil conditions.

• 농업과학연구
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• 제47권1호
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• pp.163-171
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• 2020

In this study, a large laboratory model experiment was conducted with the aim of developing an embankment reinforcement method to prevent overtopping, which is the main cause for the failure of agricultural reservoirs. The model experiment was carried out with concrete and asphalt as a permanent reinforcement method and with geomembrane as the emergency method at a deteriorated homogeneous reservoir. Under the non-reinforced conditions, the pattern of the failure appeared in several scour directions from the downstream slope as the overtopping began, and the width and depth of the erosion were magnified as it gradually moved to the dam crest. Under the conditions reinforced with asphalt and concrete, the overtopping was stabilized. In the case of the concrete reinforcement, it was found that the slope of the riprap boundary exhibited downward erosion by the current; thus, it was necessary to construct an extension up to the riprap joint of the upstream and downstream sides to prevent the expansion of the failure. Under the conditions reinforced with the geomembrane sheet, the overtopping was stabilized, and no seepage was found that required the emergency reinforcement method. Asphalt, concrete, and geomembrane sheet reinforcements have been shown to be capable of delaying failure for about 1 hour and 40 minutes compared to the non-reinforcement conditions. The reinforcement method is considered to be a very effective method to prevent disasters during overtopping. The pore water pressure can be used as useful data to predict the risk of failure at an embankment.

• 한국농공학회논문집
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• 제63권1호
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• pp.89-102
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• 2021

Soils in agricultural lands contain large amount of organic matter and nutrients due to the injected fertilizers and manure. During heavy rain, surface water and base runoff pollutants flows into a nearby stream or lake with eroded soil from agricultural lands. On the other hands, agricultural lands near the lake are inundated due to the increase of the water level in the lake, leading to organic matter and nutrient release from the inundated soil. In this study, releasing rates of nutrient salts and organic substances were analyzed for the soil in the agricultural land, where cultivation activities has been carried out and periodically flooded, to account for the possibility of contamination from the inundated agricultural land in reservoir areas The experiment results have shown that COD was released from the soil in anaerobic conditions, and T-P was released in both anaerobic and aerobic conditions. However, in the case of T-N, it was found that the runoff by soil was not made before the rainfall occurred, and when the soil was impound due to rainfall, the elution occurred under the aerobic conditions. Through the results of this study, it was possible to account for the effect of flooded agricultural lands on the water quality in the lake, and this could be reflected in an efficient agricultural non-point pollution management policy. In order to determine the precise releasing rate for each agricultural land, it is believed that the leaching experiment for paddy fields and grasslands are needed.

• 한국농공학회논문집
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• 제64권4호
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• pp.11-20
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• 2022

Currently, the operation rule of agricultural reservoirs in case of drought events follows the drought forecast warning standard of agricultural water supply. However, it is difficult to preemptively manage drought in individual reservoirs because drought forecasting standards are set according to average reservoir storage ratio such as 70%, 60%, 50%, and 40%. The equal standards based on average water level across the country could not reflect the actual drought situation in the region. In this study, we proposed the improvement of drought operation rule for agricultural reservoirs based on the percentile approach using past water level of each reservoir. The percentile approach is applied to monitor drought conditions and determine drought criteria in the U.S. Drought Monitoring (USDM). We applied the drought operation rule to reservoir storage rate in extreme 2017 spring drought year, the one of the most climatologically driest spring seasons over the 1961-2021 period of record. We counted frequency of each drought criteria which are existing and developed operation rules to compare drought operation rule determining the actual drought conditions during 2016-2017. As a result of comparing the current standard and the percentile standard with SPI6, the percentile standard showed severe-level when SPI6 showed severe drought condition, but the current standard fell short of the results. Results can be used to improve the drought operation criteria of drought events that better reflects the actual drought conditions in agricultural reservoirs.

• 한국환경농학회지
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• 제42권4호
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• pp.346-352
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• 2023

Cadusafos, an organophosphorus insecticide, has been commonly used against various pests worldwide. Organophosphorus pesticides have shorter half-lives and lower toxicities than organochlorine pesticides. However, excessive use of Cadusafos can increase pest resistance and issues with acetylcholine biomagnification, potentially resulting in human toxicity. In this study, we investigated the effect of a Cadusafos-degrading microbial agent (CDMA) prepared using Sphingobium sp. Cam5-1, which was previously reported to effectively degrade residual Cadusafos in soil. Experiments were conducted under both controlled laboratory and greenhouse field conditions. Under laboratory conditions, CDMA (10⁶ cfu/g soil application rate) decomposed 97% of Cadusafos in the soil in the untreated control after 21 days. Additionally, when CDMA (10⁶ cfu/g soil) was mixed with quicklime, 99% of Cadusafos was decomposed within 3 days. Under greenhouse field conditions, the combined effect of CDMA (10⁶ cfu/g soil) and quicklime was not observed. However, CDMA (10⁶ cfu/g soil) application alone was capable of decomposing 91% of Cadusafos after 3 days. These results indicate that CDMA can effectively decompose high residual levels of Cadusafos in soils under field conditions using a low inoculum rate.

• 농촌지도와개발
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• 제13권1호
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• pp.195-208
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• 2006

This study was carried out to analyze the working conditions and Job Satisfaction of foreigner agricultural trainees. Foreigner training program is governmental project to decrease the shortage of labor resources in farm household and increase of income for trainees, to transfer the agricultural technology to sending country. For this purpose, data were gathered from 110 foreigner agricultural trainees consisted of 91 Uzbekistanian and 19 Mongolian by interview with questionnaire. The results are as follows: 1) the trainee answered to increase the income and technical training regardless of nationality, age, wedding, and types of agriculture. 2) the trainee felt crucial difficulties in language usage and homesick during the training program, 3) Training program should be concretized in working schedule.

• 한국환경농학회지
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• 제30권4호
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• pp.382-389
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• 2011

BACKGROUND: Light-emitting diodes (LEDs) with lower electric cost and the specific wavelength have been considering as a novel light source for plant production in greenhouse conditions as well as in a closed culture system. Supplementary lighting for day-length extension was considered as light intensity, light quality, and/or photoperiod control on plant growth and development. Effects of supplementary blue or red LED radiation with lower light intensity on growth of Ageratum (Ageratum houstonianum Mill., cv. Blue Field), African marigold (Tagetes erecta L., cv. Orange Boy), and Salvia (Salvia splendens F. Sello ex Ruem & Schult., cv. Red Vista) were discussed during sunrise and sunset twilight in the experiment. METHODS AND RESULTS: Supplementary lighting by blue and red LEDs for 30 (Treatment B30; R30) or 60 (Treatment B60; R60) min. per day were established in greenhouse conditions. Photosynthetic photon flux for supplementary radiation was kept at $15{\mu}mol\;m^{-2}\;s^{-1}$ on the culture bed. Natural condition without supplementary light was considered as a control. The highest shoot and root dry weights were shown in African marigold exposed by red light for 60 min. per day. Supplementary blue and red lighting regardless of the radiation time significantly stimulated development of lateral branches in African marigold. Stem growth in Ageratum and Salvia seedlings was significantly promoted by red radiation as well as natural light. CONCLUSIONS: Extending of the radiation time at sunrise and sunset twilight using LEDs stimulated reproductive growth of flowering plant species. Different characteristics on growth under supplementary blue or red lighting conditions were also observed in the seedlings during supplementary radiation.

• 한국국제농업개발학회지
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• 제30권4호
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• pp.269-276
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• 2018

1. 중앙 아시아는 5 개의 국가로 구성되어 있으며, 이 국가들은 1991년에 소련 연방에서 독립하였다. 독립 이전에는 5개 국가 모두 공산주의 통치 하에 동일한 소비에트 계획경제 체제를 가지고 있었다 2. 1991년 이래로 중앙 아시아 국가들은 정치적, 사회적, 자연적, 지리적 조건에 따라 각기 다른 개발 경로를 경험하였다. 3. 더 나은 통치 환경은 현대 기술 혁신을 장려하고 토지에 대한 신기술의 적용 및 토지에 대한 권리를 보장하도록 동기를 부여한다. 또한 상대적으로 낮은 거래 비용이 조성될 수 있도록 지원하여 생산 증대로 이어질 투자를 촉진한다. 4. 따라서 통치 환경의 개선은 농업 생산 증대에도 중요한 요인이다. 본 연구는 통치 환경과 농업 생산과의 관계를 실증적으로 분석하고 이를 검증하였다. 5. 본 연구의 결과는 농업 생산의 증대를 위하여 통치 환경의 개선이 중요함을 입증하였으며, 그 중에서도 부패 통제 및 법의 지배의 개선이 농업 생산 증대에 가장 큰 영향을 미친다는 것을 밝혔다.

• Mycobiology
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• 제39권2호
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• pp.129-132
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• 2011

To determine the optimal media conditions for the detection of the extracellular cellulase activity in Ganoderma neo-japonicum, we varied three media conditions: dye reagent, pH, and temperature. We evaluated the use of four dyes, Congo red, phenol red, remazol brilliant blue, and trypan blue. To observe the effect of pH on the chromogenic reaction, we tested media ranging from 4.5 to 8.0. To research the effect of temperature on the clear zone and the fungus growing zone, we tested temperatures ranging from 15 to $35^{\circ}C$. On the whole, the best protocol called for Ganoderma neo-japonicum transfer onto media containing Congo red with a pH of 7.0, followed by incubation at $25^{\circ}C$ for 5 days. Our results will be useful to researchers who study extracellular enzyme activity in Ganoderma neo-japonicum.

• 한국지역지리학회지
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• 제6권3호
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• pp.37-52
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• 2000

대도시내의 농업경영이 시장접근성의 측면에서 볼 때 유리한 것은 사실이다. 그러나 농업은 필연적으로 생물학적 과정에 의존하는 산업이므로 농업경영에서 자연적 조건은 여전히 중요하다. 사례연구를 통해 대도시내 영농조건이 불리한 지역의 농업경영 특성을 고찰한 본 연구에서 경제적 측면의 농업경영과 관련해서는 토지의 자연적 제약이 중요한 요인이지만 주민의 생활측면에서는 기반시설의 부족이 더 큰 제약 요인으로 작용됨을 확인하였다. 농업노동력은 양적으로 부족하고 질적으로 낮은 수준이며, 부족한 농업노동력을 보완하는 위탁영농은 결과적으로 개별농가의 영농수익을 악화시키는 요인이 되고 있다. 경영규모와 형태는 경영주의 연령에 의해 크게 영향 받으며, 토지이용은 자연적 조건에 따라 결정되는데 특히 일사량 및 수리시설과의 접근성이 중요하게 작용된다. 기반시설의 부족에 따른 생활상의 불편함과 열악한 영농조건 및 낮은 영농수익성에도 불구하고 자급적 생계유지 목적의 영농과 촌락공동체는 유지될 가능성이 높다. 그러나 불리한 자연적 조건은 영농의 상업화를 제약하여 영농목적의 이주를 제한하고 농가경제의 영세성과 악순환을 되풀이한다 그러므로 정책적인 지원과 재배작물의 보급이 없는 한 자연적 조건이 불리한 농업지역은 대도시내에 위치하더라도 한계가 있다.