• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.199-199
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• 2019

친환경적인 산업기술인 초미세기포(Ultra Fine Bubble, 이하 UFB) 제조 기술은 농업, 수처리, 그리고 환경재생 등 다양한 분야에서 적용되고 있다. UFB는 1,000nm 이하의 크기를 가진 기포로서 용존산소를 통한 농작물 성장 촉진 및 수중의 대장균 및 세균제거 등 다양한 성질을 지니고 있다. 본 연구는 기존의 방식과는 다르게 자왜현상을 메카니즘으로 갖는 타격식으로 제조된 UFB 생성장치를 통해 생성된 200nm이하의 크기를 가진 UFB를 실제 딸기 농장에 적용하여 딸기의 성장을 모니터링하고 살균 성능을 가진 화학제품과 UFB를 대장균에 적용하여 대장균 제거효율을 비교하였다. 딸기농장에 기존에 사용되던 지하수 대신 UFB를 주입하여 딸기성장 초기단계의 DO농도를 측정하고 딸기 생식단계에 산소포화도에 대한 질산염의 농도를 측정하여 상관관계를 분석하였으며 각각의 딸기 열매를 수확하여 무게를 비교하였다. 또한 대장균이 함유되어있는 대변을 채취하여 살균 성능을 가진 화학제품과 UFB수를 각각 대장균이 포함된 실험원수와 반응시켜 배양하고 검출된 대장균 개체 수에 확인하여 제거효율을 비교분석 하였다. 딸기성장 초기단계의 DO농도 측정결과 DO농도가 6~9ml/L로 높게 유지되고 있음을 확인하였고 딸기 생식단계에서 산소포화도가 일정하게 유지되고 있음에 따라 질산염의 농도가 점차 감소하는 것을 확인하였다. 또한 수확한 열매의 무게는 각각 37g, 19g으로 UFB수를 통해 재배된 딸기가 약 2배 이상 높은 것으로 나타났다. 이와 같은 결과는 수중의 용존산소가 딸기 성장 초기에 뿌리의 발육에 긍정적인 영향을 미치고 질산염을 원활하게 섭취하게 하여 딸기의 성장이 촉진되었고 열매의 무게가 증가하였다고 판단된다. 또한 대장균이 함유된 원수, 원수+화학제품, 원수+UFB를 접종하여 대장균과 반응시켜 배양하여 대장균 개체 수를 확인한 결과, 원수의 경우 약 600개의 대장균의 개체수가 나타났고, 원수+화학제품의 경우 검출된 대장균의 개체 수는 약 300개 정도로 나타났다. 이를 희석한 비율을 계산하여 대장균 개체 수를 나타내면 원수 약 6000개/ml, 원수+화학제품 약 6000개/ml로 비슷하게 나타난다. 반면, 원수+UFB 경우 검출된 대장균의 개체 수는 1개로 희석한 비율을 계산하여 대장균 개체 수를 나타내면 약 20개/ml로 나타난다. 이와 같은 결과를 통해 UFB는 99.9%의 대장균 제거효율을 보였으며, 화학제품은 대장균 제거효율을 보이지 않았다. 따라서 화학제품은 항균기능은 작용하지만 살균기능은 거의 없다고 판단하였고, UFB의 경우 기포가 소멸하면서 발생되는 초고온, 초고압을 형성하여 주변에 존재하는 대장균을 제거하였거나, 기포가 소멸할 때 발생되는 OH 라디칼을 통해 대장균의 세포를 화학적으로 분해시켜 대장균을 제거하였다고 보인다.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.9-15
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• 2010

This study was conducted to develop a stand growth model and a stand yield table for Eucalyptus pellita and Acacia mangium plantations in Kalimantan, Indonesia. To develop a stand growth model, Weibull robability density function, a diameter class model, was applied in this study. In the development of stand growth model by site index and stand age, a hierarchy is generally required - estimation, recovery and prediction of the diameter class model. A number of grow equations were also involved in each process to estimate diameter, height, basal area, minimum or maximum diameter. To examine whether the grow equations are adequate for Eucalyptus pellita or Acacia mangium plantations, a fitness index was analyzed for each equation. The results showed that fitness indices were ranged from 65 to 89% for Eucalyptus pellita plantations and from 72 to 95% for Acacia mangium plantations. As being highly adequate for the plantations, a stand yield table was developed based on the resulted growth model, and applied to estimate the stand growth with midium site index for 10-year period. The highest annual stand growth of Eucalyptus pellita plantations was estimated to be 21.25 $m^3$/ha, while that of Acacia mangium plantations was 27.5 $m^3$/ha. In terms of annual stand growth, Acacia mangium plantations appeared to be more beneficial than Eucalyptus pellita plantations. Also, to estimate commercial timber volume available from the plantations, an assumption that a log would be cut by 2.7 m in length and the rest of the log would be cut by 1.5m was involved. The commercial timber volume available from Eucalyptus pellita plantations was 68.0 $m^3$/ha, 33% from the total stand volume, 203.2 $m^3$/ha. Also 96.7 $m^3$/ha of commercial timbers were available from Acacia mangium plantations, which was 42% from the 232.9 $m^3$/ha in total. Presenting a good information about the stand growth in Eucalyptus pellita and Acacia mangium plantations, this study might be useful for whom proceeds or considers an abroad plantation for merchantable timber production or carbon credit in tropical regions.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.424-431
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• 2017

This study was conducted to set the optimum nutrient solution concentration by growth stage for new strawberry cultivars 'Berrystar' and 'Jukhyang'(Fragaria ${\times}$ ananassa Duch. cvs. 'Berrystar', 'Jukhyang') grown through hydroponics to improve the quality and yield. Three different EC levels were applied to the nutrient solution. The treatment levels were 0.7, 1.0 and 1.3 times higher than the nutrient concentration standard for 'Seolhyang' based on the 'Manual for strawberry cultivation' of Rural Development Administration. Based on the results, there were no significant differences in growth of 'Berrystar' by EC level. 'Jukhyang' showed the most vigorous growth grown in 1.3 times higher nutrient concentration. While the growth of 'Berrystar' and 'Jukhyang' grown in higher EC level has leaves with more chlorophyll concentration. However the quantum yield of leaves was not affected by the treatments. On the treatment with 1.3 times higher EC level, the weight, length, width and firmness of 'Berrystar' and 'Jukhyang' were significantly high. The sugar contents of the harvest analyzed by HPLC did not differed particularly, but the percentage composition of reducing sugar and non-reducing sugar were presented differently depending on the treatments. Marketable fruit yield increased as nutrient concentration increases. However, there were no large differences by treatments. Meanwhile, 'Jukhyang' showed significant difference by nutrient concentration and had the largest yield for a treatment grown in 1.3 times higher EC level. Based on these results, it is recommended to provide the same nutrient solution concentration level to the nutrient concentration standard of 'Seolhyang' for 'Berrystar', and the 1.3 times higher level for 'Jukhyang'.

• Journal of Mushroom
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• v.13 no.2
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• pp.108-113
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• 2015

This study was carried out to investigate the feeding effects of dietary supplementation of fermented spent mushroom substrates (F-SMS) from Pleurotus eryngii with Bacillus subtilis CS21 and Saccharomyces cerevisiae on Hanwoo steers. The cellulase and xylanase producing bacteria, designated CS21, was isolated from freshly spent mushroom substrates from Pleurotus eryngii and used as probiotics to fermented spent mushroom substrates. Twenty Hanwoo steers were allocated into two feeding groups and assigned equally to two dietary treatments; Control (TMR) and TMR including 30% F-SMS (30% F-SMS TMR). Total gain and feed intake was significantly greater in the 30% F-SMS TMR than control (p<0.05), but carcass grades were not influenced by the experimental diets. Based on this study, fermented spent mushroom substrates from Pleurotus eryngii with B. subtilis CS21 and Saccharomyces cerevisiae is able to use as an ingredient feed in TMR for Hanwoo steers.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1216-1221
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• 2012

This study is aimed to investigate microbiological contamination of Angelica gigas Nakai. A total of 111 samples including root, soil, and irrigation water were collected from farms and market to detect aerobic bacteria, Bacillus cereus, coliform, Escherichia coli, Listeria monocytogenes,. Salmonella spp., and Staphylococcus aureus. The contaminations of aerobic bacteria, coliform, and Bacillus cereus in the root during cultivation were found 6.71 log CFU $g^{-1}$, 4.13 log CFU $g^{-1}$, and 3.54 log CFU $g^{-1}$, respectively. The contamination of coliform and B. cereus were detected in all steps from harvesting to processing, with the highest count recorded from the cutting step. In marketing, the contaminations of aerobic bacterial, coliform, and B. cereus were 5.5~6.0 log CFU $g^{-1}$, 2.4~2.6 log CFU $g^{-1}$, and 3.5~4.0 log CFU $g^{-1}$, respectively. Listeria monocytogenes, Salmonella spp, and Staphylococcus aureus were not detected in any of samples. This result indicated that hygienic soil management and post harvest management should be performed to reduce the contamination of hazard microorganisms and to produce safe agro-products.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.333-339
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• 2015

A thermal time-based phenology model of Kimchi cabbage was developed by using the field observed growth and temperature data for the purpose of accurately predicting heading and harvest dates among diverse cropping systems. In this model the lifecycle of Kimchi cabbage was separated into the growth stage and the heading stage, while the growth amount of each stage was calculated by optimal mathematical functions describing the response curves for different temperature regimes. The parameter for individual functions were derived from the 2012-2014 crop status report collected from seven farms with different cropping systems located in major Kimchi cabbage production area of South Korea (i.e., alpine Gangwon Province for the summer cultivation and coastal plains in Jeonnam Province for the autumn cultivation). For the model validation, we used an independent data set consisting of local temperature data restored by a geospatial correction scheme and observed harvest dates from 17 farms. The results showed that the root mean square error averaged across the location and time period (2012-2014) was 5.3 days for the harvest date. This model is expected to enhance the utilization of the Korea Meteorological Administration's daily temperature data in issuing agrometeorological forecasts for developmental stages of Kimchi cabbage grown widely in South Korea.

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.289-295
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• 2011

Produce, including leafy vegetables, has been implicated in several outbreaks of food illness. To evaluate microbiological safety of lettuce and it's cultivation area, a total of 147 samples were collected from lettuce farms and post harvest facility at Icheon, Gyeonggi province. The collected samples were assessed for presence of sanitary indicator microorganisms (Aerobic plate count, coliform count, Escherichia coli) and foodborne pathogens (Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus). The population of APC was over 4.0 log CFU from most of the samples. While the numbers of APC, and coliform of lettuce at 62 days after transplanting were 4.18 log CFU/g, and 1.00 log CFU/g, respectively, those of 10 days after transplanting were 5.37 log CFU/g, and 2.87 log CFU/g, respectively. B. cereus was highly detected from soil and balance which were contaminated with 3.5 log CFU/g, and 2.6 log CFU/100 $cm^2$, respectively. The number of E. coli recovered from gloves was 3.5 log CFU/hand. However, E. coli O157:H7, Salmonella spp., and L. monocytogenes were not detected. These data suggested that risk management system should be introduced to lettuce farms to enhance safety of lettuce.

• Journal of Radiation Protection and Research
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• v.28 no.1
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• pp.9-18
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• 2003

Rice plants at different seed-developing stages were exposed to HTO vapor in an exposure box for 1 h during daytime and nighttime to investigate the levels of tissue free water $^3H$ (TFWT) and organically bound $^3H$ (OBT) in different plant parts. In the daytime experiment, TFWT concentrations in leaves at the end of exposure $(h_0)$ were around 100% of the 1 hour mean HTO concentrations in air moisture whereas in the nighttime experiment, they were as low as $30{\sim}40%$ of the air concentration. TFWT concentrations in both experiments decreased very rapidly in the beginning but much mote slowly later and those at harvest were hundreds to hundred thousands times lower than those at $h_0$. OBT concentrations varied with time in different manners depending on plant parts and exposure times and differed between at $h_0$ and at harvest by factors of less than 10 on the whole. Even during nighttime exposures, OBT was produced at about a third the rate for daytime exposures. The degree of the conversion of airborne HTO into OBT in mature rice seeds, being several times higher in the daytime experiment than in the nighttime experiment, was highest after the exposure peformed at the most actively seed-developing stage for both experiments. It is estimated that OBT would contribute much more to the ingestion radiation dose than TFWT if rice plants are exposed to HTO vapor for the seed-developing period.

• Applied Biological Chemistry
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• v.47 no.2
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• pp.238-243
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• 2004

To investigate the changes in content of residual pesticides for safety production of young radishes in the production steps in greenhouse and to evaluate the safety of young radishes in the final consuming step, biological half-life of pesticides (diazinon, endosulfan) in packaging products was studied. Samples were collected regularly from 2 hours to 10 days after the distribution of pesticides in young radishes. The contents of residual pesticides in young radishes during cultivating in greenhouse as the levels of distribution concentrations reduced with time. During 10 days of pesticides distribution, decomposition rate of pesticides were diazinon > endosulfan. A half-life of endosulfan was 0.6 day longer than diazinon because endosulfan derived persistent endosulfan sulfate. To produce the safe young radish, after the distribution of the pesticides the desirable harvest time based on maximum residue limit (MRL) was 6th day diazinon for and 10th day for endosulfan.

• Journal of Applied Biological Chemistry
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• v.65 no.3
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• pp.173-181
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• 2022

This study was carried out to investigate the residual characteristics of flubendiamide in kale to establish pre-harvest residue limits (PHRL) and the removal efficiency according to the washing solvent and method. Field tests were conducted at two different greenhouses, field 1 (Anseong-si, Gyeonggi-do) and field 2 (Incheon-si, Gyeonggi-do). According to the safe use guidelines kale was sprayed with flubendiamide twice every 10 days and harvested 0 (after 2 h), 1, 2, 3, 5, 7 and 10 days after the final application. The biological half-live of flubendiamide in kale was calculated based on dissipation curves of the pesticide in samples analyzed by liquid chromatography coupled with tandem mass spectrometry. In the analysis, method limits of quantitation (MLOQ) were 0.01 mg/kg, and recoveries performed with two different fortification levels of 10 MLOQ and maximum residue limit (0.7 mg/kg) were 104.2±3.6 and 101.9±10.2%, respectively. The dissipation rate constant of flubendiamide in kales were 0.2437 at field 1 and 0.1981 at field 2. PHRL calculation equations obtained using the dissipation constants estimated as follows: if the residual concentration of flubendiamide in kale on 10 days before harvest is less than 8.0 mg/kg, the residual concentration on the harvest would be under MRL. The removal of flubendiamide from kale was the greatest when it was washed with vinegar (39.8%), followed by baking soda (31.7%), calcium powder (30.2%), neutral detergent (27.2%), and tap water (15.9%). The results of this study would be useful for both farmers and consumers to produce or consume safe agricultural products.