• Journal of Food Hygiene and Safety
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• v.24 no.2
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• pp.174-181
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• 2009

The consumption of "ready-to-eat" agricultural products is recently increasing and the safety of these agricultural products is forefront of public concerns. The 120 samples of paprikas, strawberries and tomatoes, which are the representative exported agricultural products, were purchased at the department stores and discount stores in Daejeon. And we determined the microbiological and parasitological contamination level of these agricultural products using culture media, multiplex PCR, commercial bacterial detection kit and microscopy, and also evaluated the decontamination method. Mean counts of total aerobic bacteria from these agricultural products ranged from $1.3{\times}10^4$ CFU/g to $1.8{\times}10^5$ CFU/g, and mean counts of coliforms ranged from $1.4{\times}10^3$ CFU/g to $9.6{\times}10^3$ CFU/g. There was no significant difference in the level of bacterial contamination between the agricultural products from department stores and the ones from discount stores. Strawberry showed the highest contamination level for the bacteria and we also found the unidentified parasite eggs. Enterobacter cloacae was the most frequently isolated bacteria strain, but no food poisoning pathogenic bacteria except Staphylococcus aureus was isolated from the products by multiplex PCR. Compared to unwashed products, tab water-washed ones showed 80% decrease of the counts of total aerobic bacteria on the agricultural products, and the rates decreased more by incorporating detergent or ultrasonic wave treatment. We concluded that the biological contamination levels among paprikas, strawberries and tomatoes were the highest in strawberries, but there were not significant difference according to distribution systems.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.477-488
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• 2020

Recently, foodborne illness outbreaks linked to fresh produce are being increasingly reported in the United States, the EU, and Korea as well. Some of this increase may be due to improved surveillance, increase in consumption, change in consumers' habits, and complex distribution systems. Garlic chive is a green, fresh-cut vegetable consumed year-round as a nutrition-rich herb in Korea. It is also prone to contamination with foodborne pathogens during pre-harvest, as amendment with high amounts of livestock manure or compost to soil is required in its cultivation. Our aim in this study was to evaluate microbial contamination of garlic chives, garlic chives cultivation soil, compost, and irrigation water in the southern part of Korea. Samples were collected in A, B, and C regions in 2019 and 2020, and 69, 72, 27, and 40 of garlic chives, soil, compost, and irrigated water, respectively, were analyzed for the presence of sanitary indicator bacteria (total aerobic bacteria, coliforms and Escherichia coli), Bacillus cereus, Staphylococcus aureus, pathogenic E. coli, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. In A, B, and C regions, levels of total aerobic bacteria, coliform, B. cereus, and S. aureus on all samples were between 1.14 and 8.83 log CFU/g, 0.43 and 5.01 log CFU/g, 0.41 and 5.55 log CFU/g, and 1.81 and 6.27 log CFU/g, respectively. B. cereus isolated from garlic chives and environmental samples showed β-hemolysis activity. Incidence of S. aureus in garlic chive and its production environments in 2020 was different from 2019. In this study, B. cereus and S. aureus were the only pathogenic microorganisms detected in all samples. As a result, this work suggests that continuous monitoring in the production and pre-harvest environment is required to improve hthe hygiene and safety of garlic chive.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.318-329
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• 2014

In order to gain insight into the physiological responses of plants to high temperature stress, the effects of temperature on Chinese cabbage (Brassica campestris subsp. napus var. pekinensis cv. Detong) were investigated through analyses of photosynthesis and chlorophyll fluorescence under 3 different temperatures in the temperature gradient tunnel. Growth (leaf length and number of leaves) during the rosette stage was greater at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures than at ambient temperature. Photosynthetic $CO_2$ fixation rates of Chinese cabbage grown under the different temperatures did not differ significantly. However, dark respiration rate was significantly higher in the cabbage that developed under ambient temperature relative to elevated temperature. Furthermore, elevated growth temperature increased transpiration rate and stomatal conductance resulting in an overall decrease of water use efficiency. The chlorophyll a fluorescence transient was also considerably affected by high temperature stress; the fluorescence yield $F_J$, $F_I$, and $F_P$ decreased considerably at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, with induction of $F_K$ and decrease of $F_V/F_O$. The values of RC/CS, ABS/CS, TRo/CS, and ETo/CS decreased considerably, while DIo/CS increased with increased growth temperature. The symptoms of soft-rot disease were observed in the inner part of the cabbage heads after 7, 9, and/or 10 weeks of cultivation at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, but not in the cabbage heads growing at ambient temperature. These results show that Chinese cabbage could be negatively affected by high temperature under a future climate change scenario. Therefore, to maintain the high productivity and quality of Chinese cabbage, it may be necessary to develop new high temperature tolerant cultivars or to markedly improve cropping systems. In addition, it would be possible to use the non-invasive fluorescence parameters $F_O$, $F_V/F_M$, and $F_V/F_O$, as well as $F_K$, $M_O$, $S_M$, RC/CS, ETo/CS, $PI_{abs}$, and $SFI_{abs}$ (which were selected in this study), to quantitatively determine the physiological status of plants in response to high temperature stresses.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.38-45
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• 2017

We investigated the effects of rising temperatures on the photosynthesis, mineral composition, and growth of radish (Raphanus sativus var. hortensis) in a winter cropping system using a temperature gradient tunnel to predict the impact of rising global temperatures. Vegetative growth, including shoot and root fresh and dry weights, shoot length, and root length and diameter, was high under elevated temperatures (ambient $+4^{\circ}C$ and $+7^{\circ}C$) compared with ambient temperature. At elevated temperatures, the N, P, Ca, Mg, and Fe contents were high in shoots, whereas in roots, the K, Ca, Mg, and Fe contents were high and the Cu content was low. The maximum photosynthetic rates ($22.1{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at ambient temperature $+4^{\circ}C$ and $22.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at ambient temperature $+7^{\circ}C$) at elevated temperatures were more than twice that ($9.7{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) at ambient temperature, whereas the water use efficiency was lower at elevated temperatures. These results suggest that rising global temperatures will lead to increased mineral absorption and photosynthesis in radish in winter cropping systems, subsequently favoring plant growth, although the water requirements will be high.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.871-877
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• 2016

Recycling nutrient solutions in closed hydroponic production systems is usually accompanied by an imbalance of nutrient solutions when concentration is controlled according to electrical conductivity (EC) levels. This study investigated whether it was possible to automatically control the concentrations of five essential elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) using only N, K and Ca ion sensors. N, P, K, Ca, and Mg uptake was measured in the nutrient solution, and relationships between absorbed ions were analyzed through twice-repeated experiments in lettuce. Results confirmed that the pattern of $PO_4$ ion uptake was similar that of N, and the pattern of Mg ion uptake was similar that of Ca. $PO_4$ ion uptake was most highly correlated with N, and Mg was most highly correlated with Ca. Regression coefficients of N and $PO_4$ were significantly different at 1.04 and 0.55, respectively, but were similar between Ca and Mg at 0.35 and 0.40, respectively. Additional experiments were conducted to measure nutrient uptake in pak choi and rose plants, both to confirm the results from the first experiment in lettuce, and to assess possible application to other crops. Coefficients of determination both for N and $PO_4$, and Ca and Mg were considerably high ($R^2=0.86$) in cultured pak choi, and similar results were observed in cultured rose ($R^2=0.87$ and 0.73, respectively). Regression coefficients for cultured pak choi were 0.56 and 0.24, respectively, and for rose were 0.51 and 0.16, respectively. Although the results obtained for N and $PO_4$ were not consistent between the lettuce experiments, N and $PO_4$ have similar regression coefficients for all crops. No common coefficient was found between Ca and Mg.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.93-99
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• 2012

In this study, the evaluation of antioxidative activity and componential analysis of C. obtusa leaf extracts was carried out. Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of C. obtusa leaf extracts on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The ethyl acetate fraction ($OSC_{50}$; 0.22 ${\mu}g/mL$) and aglycone fraction of C. obtusa leaf extracts (0.20 ${\mu}g/mL$) showed about 7 times more prominent ROS scavenging activity than L-ascorbic acid (1.50 ${\mu}g/mL$). The cellular protective effects of fractions obtained from C. obtusa leaf extracts on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The ethyl acetate fraction and aglycone fraction of C. obtusa leaf extracts showed the cellular protective effects in a concentration dependent manner (5~25 ${\mu}g/mL$). The inhibitory effect ($IC_{50}$) of ethyl acetate fraction and aglycone fraction on tyrosinase exhibited 74.43 and 53.80 ${\mu}g/mL$, repectively. The aglycone fraction showed four times higher tyrosinase inhibitory effect than arbutin (226.88 ${\mu}g/mL$), known as a whitening agent. The aglycone fraction of C. obtusa leaf extracts showed three bands in TLC chromatogram and three peaks in HPLC chromatogram (360 nm). Three compounds were identified as taxifolin, quercetin and kaempferol. These results indicate that the fractions of C. obtusa leaf extracts can function as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against reactive oxygen species. The fractions of C. obtusa leaf extracts can be applicable to new functional cosmetics for antioxidan and whitening effects.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.206-215
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• 2008

Temporal and spatial distributions of salinity, temperature, dissolved oxygen (DO), and turbidity were investigated at seven sites in the upper regions of brackish Lake Sihwa with a limited water exchange, from March to October 2005. During the study period, salinity and temperature varied $0.1{\sim}29.9\;psu$ and $4.7{\sim}28.1^{\circ}C$, respectively, depending on seasons and sites sampled. A distinct halocline profile showing the maximum density gradient (difference over $20\;psu\;m^{-1}$ between surface and bottom layers) was observed during the rainy season, due to the decrease of salinity in surface layers by freshwater inflow. This result implies that rainfall event is the important factor forming the halocline. On the other hand, the depth and location of haloeline varied with the amount of seawater through the sluice gates and the operation systems (inflow or outflow). High DO (over 300% saturation) was observed at surface layer above the halocline in April when red tide occurred, whereas low DO (below 20% saturation) was at the bottom layer below the halocline in the rainy season. Turbidity ranged $1.5{\sim}80.3\;NTU$ showing the maximum turbidity at the layers above or upper the halocline. As a result, the distributions of DO and turbidity in the upper regions of brackish Lake Sihwa were largely affected by the variation of salinity. Also, when the halocline was formed, the water quality between upper and lower water layers may be expected completely different. This study suggests that the physicochemical characteristics of water in the brackish regions are closely associated with the causes of eutrophication such as red tide and DO deficit.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.1-15
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• 2017

Daecheong Reservoir was made by the construction of a large dam (>15 m in height) on the middle to downstream of the Geum River and the discharge systems have the watergate-spillway (WS), a hydropower penstock (HPP), and two intake towers. The purpose of this study was to investigate the limnological anomalies of turbid water reduction, green algae phenomenon, and oligotrophic state in the lower part of reservoir dam site, and compared with hydro-meteorological factors. Field surveys were conducted in two stations of near dam and the outlet of HPP with one week intervals from January to December 2000. Rainfall was closely related to the fluctuations of inflow, outflow and water level. The rainfall pattern was depended on the storm of monsoon and typhoon, and the increase of discharge and turbidity responded more strongly to the intensity than the frequency. Water temperature and DO fluctuations within the reservoir water layer were influenced by meteorological and hydrological events, and these were mainly caused by water level fluctuation based on temperature stratification, density current and discharge types. The discharges of WS and HPP induced to the flow of water bodies and the outflows of turbid water and nutrients such as nitrogen and phosphorus, respectively. Especially, when hypoxic or low-oxygen condition was present in the bottom water, the discharge through HPP has contributed significantly to the outflow of phosphorus released from the sediment into the downstream of dam. In addition, HPP effluent which be continuously operated throughout the year, was the main factor that could change to a low trophic level in the downreservoir (lacustrine zone). And water-bloom (green-tide) occurring in the lower part of reservoir was the result that the water body of upreservoir being transported and diffused toward the downreseroir, when discharging through the WS. Finally, the hydropower effluent was included the importance and dynamics that could have a temporal and spatial impacts on the physical, chemical and biological factors of the reservoir ecosystem.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.81-92
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• 2011

When we bury the infected poultry into the ground, we have many problems such as the difficulty of making sufficient area for burying, environmental contamination by the leachate, unpleasant ordor. Also, in case of burning the carcass of the infected poultry, there are some problems such as high cost, dust, unpleasant odor, etc. It could cause environmental contamination which many peoples and environmental organization complains about. In this study, we develop a treating system which treats the infected poultry carcass in a environmental method preventing the environment contamination. This system is composed of many processes. The euthanasia system uses rigid vinyl to trap and to do a euthanasia the infected poultry with lethal gas, carbon dioxide. And then, with the tractor attached grappler infected poultry carcass could be put into the carcass treating system. The euthanasia system uses rigid vinyl to trap the infected birds and to confine lethal gas, carbon dioxide. Infected poultry carcass are moved to carcass disposal system by collecting device which is attached at tractor. The carcass treatment system (capacity of disposal : 6.3 $m^3$) is installed on a truck and do one pass work, which is input, crush, stir, sterilize, and discharge treated carcass. 1,000 chickens was killed within 9.7min by $CO_2$ (300L/min) in the tent (10 $m^3$). The collecting device could carry 142 chickens at a time, and the movable carcass treatment system could sterilize 2 tons carcass per hour (at one time). This treatment systems was eco-friendly because it reduced the volume of carcass by 31.9% with no wastewater generation.

• Journal of Animal Environmental Science
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• v.16 no.2
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• pp.153-160
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• 2010

Recently, the treatment of dead poultry has become more important issue because, the infected poultry, which was buried under the ground, causes environmental contaminations such as steep water and reek occurrence, etc. Therefore, in this study, we investigated the type of treatment and the composting methods influencing to the characteristics on decomposition and fermentative disinfection of dead poultry with poultry manure and sawdust. The results of the port tests showed that amputated poultry treated by the cut-sterilization were not only more decomposed, with less smell compared to the non-treated poultry carcass. When we treated thermophilic microorganism such as bacillus in this amputated poultry, the temperature of treated poultry increased much fester, the fermentation temperature didn't rise and not maintained constantly for long time due to the small size of the fermentation port. On the other hand, we did fermentation test by the layered disposal method with more poultry. In this experiment, the temperature of fermented poultry rose to $54^{\circ}C$ in a day and maintained around $55^{\circ}C$ during four weeks period. With less odor outside the experiment room. further. Also, we inoculated AI virus, ND virus in the excrement for studying the effect of fermentative disinfection. The result of the test revealed that AI virus was destructed within 60 minutes and ND virus was destructed within 30 minutes at the temperature of $56^{\circ}C$. Therefore, the investigations revealed scope of composting method for steam sterilized infected poultry in the originated area mixed with poultry manure, sawdust by thermophilic microorganism could increase the effectiveness of fermentative disinfection and decrease the environmental contamination.