• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.39-47
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• 2021

With rising concerns about pesticide spray drifts, this study analyzed the drift patterns of two typically-used nozzles, XR nozzle and AI nozzle, concerning their working pressures and wind speeds by wind tunnel experiments. AI nozzle showed low drift potential with larger droplet sizes compared to XR nozzle. Airborne and deposition drifts of XR nozzle were two times higher than those of AI nozzle under high wind speeds (≥2 m s^-1). In all cases, higher working pressures decreased the droplet sizes, thereby increasing the airborne and deposition drifts. Higher wind speeds also resulted in more airborne drifts, while ground deposition was increased under lower wind speeds. These effects of working pressures and wind speeds on the airborne and deposition drifts were observed at leeward distances less than 4 m from the nozzles. However, the airborne and deposition drifts were barely affected by the working pressures and wind speeds at leeward distances more than 11 m. The measurements were fitted to regression models of the drift curve with acceptable R² values greater than 0.8, demonstrating that further studies will be useful to settle domestic issues of spray drifts.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.749-760
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• 2022

Omics-driven synthetic biology is a multidisciplinary research field that creates new artificial life by employing genetic components, biological devices, and engineering technique based on genetic knowledge and technological expertise. It is also utilized to make valuable biomaterials with limited production via current organisms faster, more efficient, and in huge quantities. As the bioeconomic age begins, and the global synthetic biology market becomes more competitive, investment in research and development (R&D) and associated sectors has grown considerably. By overcoming the constraints of present biotechnologies through the merging of big data and artificial intelligence technologies, huge ripple effects are envisaged in the pharmaceutical, chemical, and energy industries. In agriculture, synthetic biology is being used to solve current agricultural problems and develop sustainable agricultural systems by increasing crop productivity, implementing low-carbon agriculture, and developing plant-based, high-value-added bio-materials such as vaccines for diagnosing and preventing livestock diseases. As international regulatory debates on synthetic biology are now underway, discussions should also take place in our country for the growth of bioindustries and the dissemination of research findings. Furthermore, the system must be improved to facilitate practical application and to enhance the risk evaluation technology and management system.

• Carbon letters
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• v.26
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• pp.88-94
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• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.5
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• pp.61-68
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• 1988

This paper reports the basic performance of a naturally aspirated DI diesel engine which is used widely in industry and agriculture when vegetable oils are used as fuel substitutes. In this paper, the properties of vegetable oils as diesel fuel were investigated and the load-performance of diesel engine when vegetable oils were used, as tested compared against diesel fuel. The general objective of this investigation is to realize an efficient, clean, and low carbon deposit combustion of the vegetable oils in diesel engines, showing their feasibility as diesel fuel substitutes. The results of this experiment were as follows; (1) Compared with diesel fuel, the droplet size of vegetable oil is very large. (2) Compared with diesel fuel, rapeseed oil, palm oil, and their blend fuels offered lower smoke, lower NOx, ower engine noise, and high thermal efficiency in a D.I. diesel engine However, there were carbon deposit and piston ring sticking problems with long-term operation. (3) For ethanol-rapeseed oil blends, a 10-20% of ethanol content is recommended to enable lower BSHC and less smoke without a remarkable increase in engine noise compared with pure rapeseed oil. (4) A 10% oxygen content in the vegetable oils is contributed to reduced smoke emission.

• Journal of Agricultural Extension & Community Development
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• v.16 no.2
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• pp.363-384
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• 2009

This study aimed at finding directions for Korean agriculture to establish a new paradigm of sustainable development. Various problematic issues and concerns in the environment necessitate the transformation of Korea's development paradigm from unconditional growth to "Green Growth" through new policies on green value and review of various advanced researches. In this research, the environment-friendly agriculture's problems, particularly in agribusiness were analyzed. Drawing from Michael Porter's Value Chain Analysis, this research developed a value chain model in agriculture that reflects the environment and the present situations. Future directions in the agriculture sector were also discussed. Korea realized food self-sufficiency through the green revolution in the early 1970s. However, a lot of problems have also occurred, including ground and water pollution and the destruction of ecosystems as a result of the overuse of pesticides and chemical fertilizers. In the late 1970s, the growing interest on environment-friendly agriculture led to the introduction of sustainable methods and techniques. Unfortunately however, these were not innovative enough to foster environment-friendly agriculture. Thereafter, the consumers' distrust on agricultural products has worsened and concerns about health have increased. In view of this, the Ministry of Food, Agriculture, Forestry and Fisheries introduced in December 1993 a system of Quality-Certified Products for organic and pesticide-free agri-foods. Although a fundamental step toward the sustainability of the global environment, this system was not enough to promote environment-friendly agriculture. In 2008, Korea's vision is for "Low Carbon Green Growth" to move forward while also coping with climate change. But primary sectors in a typical value chain do not consider the green value of their operations nor look at production from an environmental perspective. In order to attain sustainable development, there is a need to use less resources and energy than what is presently used in Korean agricultural and value production. The typical value chain should be transformed into a "closed-loop" such that the beginning and the end of the chain are linked together. Such structure allows the flow of materials, products and even wastes among participants in the chain in a sustained cycle. This may result in a zero-waste sustainable production without destroying the ecosystem.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.1
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• pp.73-79
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• 2004

The objective of the present study was to determine whether ${\beta}$1-4 galacto-oligosaccharides (GOS) and Candida kefyr combined with nitrate as manipulators could suppress rumen methanogenesis without nitrate poisoning in sheep. Four rumen fistulated wethers were allocated to a $4{\times}4$ Latin square design. Nitrate (1.3 g $NaNO_3$ $Kg^{-0.75}$body weight) with and without GOS and Candida kefyr were administered into the rumen through fistula as a single dose 30 min after the morning meal. GOS and Candida kefyr were supplemented by sprinkling onto the feed and through rumen fistula, respectively. The four treatments consisted of saline, nitrate, nitrate plus GOS and nitrate plus GOS plus Candida kefyr. Physiological saline was used as the control treatment. Compared to saline treatment, the administration of nitrate alone resulted in a very marked decrease in rumen methanogenesis and an increase in rumen and plasma nitrite production and blood methaemoglobin formation consequently causing a decline in oxygen consumption, carbon dioxide production and metabolic rate. When compared to nitrate alone, the simultaneous administration of nitrate with GOS decreased nitrite accumulation in rumen and plasma and nitrate-induced methaemoglobin, while retaining low methane production. However, GOS could not fully restore metabolic parameters reduced by nitrate. When compared to the simultaneous administration of nitrate with GOS, the simultaneous administration of nitrate with GOS plus Candida kefyr lowered rumen methanogenesis to a negligible level, but did not decrease rumen and plasma nitrite accumulation as well as blood methaemoglobin formation. Thus, these results suggest that combination of nitrate with GOS may be a potent manipulator to suppress rumen methanogenesis with abating the hazards of nitratenitrite toxicity in ruminants.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.428-434
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• 2012

A fungal strain, capable of solubilizing insoluble phosphate under diverse temperature, pH and salt conditions was isolated from Waste Mushroom bed of Agaricus bisporus in South Korea. Based on 18S rRNA analysis, the strain was identified as Aspergillus awamori bxq33110. The strain showed maximum phosphate solubilization in AYG medium (525 ${\mu}g\;mL^{-1}$) followed by NBRIP medium (515 ${\mu}g\;mL^{-1}$). The strain solubilized $Ca_3(PO_4)_2$ to a greater extent and rock phosphate and $FePO_4$ to a certain extent. However $AlPO_4$ solubilizing ability of the strain was found to be very low. Glucose at the rate of 2% ($561{\mu}g\;mL^{-1}$) was found be the best carbon source for Aspergillus awamori bxq33110 to solubilize maximum amount of phosphate. However, no significant difference ($P{\leq}0.05$) in phosphorus solubilization was found between 1% and 2% glucose concentrations. $(NH_4)_2SO_4$ was the best nitrogen source for Aspergillus awamori bxq33110 followed by $NH_4Cl$ and $NH_4NO_3$. At pH 7, temperature $30^{\circ}C$ and 5% salt concentration (674 ${\mu}g\;mL^{-1}$) were found to be the optimal conditions for insoluble phosphate solubilization. However, strain Aspergillus awamori bxq33110 was shown to have the ability to solublize phosphate under different stress conditions at $30-40^{\circ}C$ temperature, pH 7-10 and 0-10% salt concentrations indicating it's potential to be used as bio-inoculants in different environmental conditions.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1811-1817
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• 2007

Extracellular enzymes from Lentinus edodes M290 on normal woods (Quercus mongolica) and waste logs from oak mushroom production were comparatively investigated. Endoglucanase, cellobiohydrolase, ${\beta}$-glucosidase, and xylanase activities were higher on waste mushroom logs than on normal woods after 1. edodes M290 inoculation. Xylanase activity was especially different, with a three times higher activity on waste mushroom logs. When the waste mushroom logs were used as a carbon source, a new 35 kDa protein appeared. After the purification, the optimal pH and temperature for xylanase activity were determined to be 4.0 and $50^{\circ}C$, respectively. More than 50% of the optimal xylanase activity was retained when the temperature was increased from 20 to $60^{\circ}C$, after a 240 min reaction. At $40^{\circ}C$, the xylanase maintained 93% of the optimal activity, after a 240 min reaction. The purified xylanase showed a very high homology to the xylanase family 10 from Aspergillus terreus by LC/MS-MS analysis. The highest Xcorr (1.737) was obtained from the peptide KWI SQGIPIDGIG SQTHLGSGGS WTVK originated from Aspergillus terreus, indicating that the 35 kDa protein was xylanase. This protein showed low homology to a previously reported L. edodes xylanase sequence.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.522-527
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• 2005

Various processes which produce L-lactic acid using ammonia-tolerant mutant strain, Rhizopus sp. MK-96-1196, in a 3L airlift bioreactor were evaluated. When the fed-batch culture was carried out by keeping the glucose concentration at 30g/L, more than 140 g/L of L-lactic acid was produced with a product yield of 83%. In the case of the batch culture with 200g/L of initial glucose concentration, 121g/L of L-lactic acid was obtained but the low product yield based on the amount of glucose consumed. In the case of a continuous culture, 1.5g/L/h of the volumetric productivity with a product yield of 71% was achieved at dilution rate of $0.024\;h^{-1}$. Basis on these results three processes were evaluated by simple variable cost estimation including carbon source, steam, and waste treatment costs. The total variable costs of the fed-batch and continuous cultures were 88% and 140%, respectively, compared to that of batch culture. The fed-batch culture with high L-lactic acid concentration and high product yield decreased variable costs, and was the best-suited for the industrial production of L-lactic acid.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.580-595
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• 2021

Although late blight is an important disease in ecofriendly potato cultivation in Korea, it is highly dependent on the use of eco-friendly agricultural materials and the development of biological control technology is low. It is a necessary to develop an effective biocontrol agent to inactivate late blight in the field. AFB2-2 strain is a gram-positive with peritrichous flagella. It can utilize 20 types of carbon sources, like L-arabinose, and D-trehalose at 35℃. The optimal growth temperature of the strain is 37℃. It can survive at 20-50℃ in tryptic soy broth. The maximum salt concentration tolerated by AFB2-2 strain is 7.5% NaCl. AFB2-2 strain inhibited the mycelial growth of seven plant pathogens by an average inhibitory zone of 10.2 mm or more. Among the concentrations of AFB2-2, 10⁷ cfu/ml showed the highest control value of 85.7% in the greenhouse. Among the three concentrations of AFB2-2, the disease incidence and severity of potato late blight at 10⁷ cfu/ml was lowest at 0.07 and 6.7, respectively. The nucleotide sequences of AFB2-2 strain were searched in the NCBI GenBank; Bacillus siamensis strain KCTC 13613, Bacillus velezensis strain CR-502, and Bacillus amyloliquefaciens strain DSM7 were found to have a genetic similarity of 99.7%, 99.7%, and 99.5%, respectively. The AFB2-2 strain was found to harbor the biosynthetic genes for bacillomycin D, iturin, and surfactin. Obtained data recommended that the B. velezensis AFB2-2 strain could be considered as a promising biocontrol agent for P. infestans in the field.