• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.200-209
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• 2008

Particle fluxes were measured with a time-series sediment trap from July 2003 to June 2005 at the St. KOMO(KOMO; Korea Deep-Sea Environmental Study Long-Term Monitoring Station, $10^{\circ}30'N,\;131^{\circ}20'W$) in the northeastern Pacific. Total mass fluxes at a depth of 4,960 m showed distinct seasonal variations with high values in the winter(December-February) and spring(March-May) and low values in the summer(June-August) and fall(September-November). Biogenic origin fluxes also displayed distinct seasonal variations similar to total mass fluxes. Particularly, calcium carbonate fluxes in winter and spring were more than two times greater than those in summer and fall. The prominent seasonal variations of total mass and biogenic fluxes were closely related with the seasonal changes of primary production in the surface waters; in winter and spring, primary production increased due to the enhanced supply of nutrients below the surface mixed layer by strong wind and less stratification, whereas it decreased as a result of the less supply of nutrient by reduced wind speed and strong stratification in summer and fall. The seasonal variations of total mass and biogenic fluxes in this study were higher than the differences of total mass and biogenic fluxes caused by the environmental changes such as El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ events in the previous studies. In order to understand the effects of El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ on the particle flux, therefore, the seasonal variation of particle flux in the northeastern equatorial Pacific needs to be well defined.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.147-158
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• 2007

To clarify the bloom pattern and species succession in phytoplankton community, the population dynamics with the determination of physico-chemical factors have been studies in Masan Bay, the south sea of Korea, for the periods November 2003-October 2004. Concentration of $NH_4-N$ was always higher than that of $NO_3-N$, which was similar level as compared to other costal areas. $PO_4-P$ concentration was lower than those in other coastal areas but similar to oligotrophic environments. Thus, phosphate seems the limiting nutrient rather than nitrogen. $SiO_2-Si$ concentration was also low as compared to other costal areas. Si:P ratio was low from autumn to winter, suggesting silicate and/or phosphate limitation during this period. The cell density of phytoplankton was high in winter 2003 and early autumn 2004. The carbon biomass was high in winter 2003 and summer 2004. And chlorophyll-a concentration was high in late autumn 2003 and summer 2004. Among 78 species of phytoplankton found in the bay during the investigated period, dominant species were two diatoms of Cylindrotheca closterium, Skeletonema costatum, and three dinoflagellates of Heterocapsa triquetra, Prorocentrum minimum, P. triestinum, and one raphidophyte of Heterosigma akashiwo. P. minimum dominated from late autumn to winter, but it was replaced by H. triquetra in late winter. P. triestinum dominated from late spring to early summer. Simultaneously, H. akashiwo cell density steadily increased, and it became dominant with C. closterium in late summer. With decreasing of H. akashiwo and C. closterium, S. costatum became the most dominant species in autumn. The canonical analyses showed that total phytoplankton cell density related to diatom cell density and it was affected by temperature, and concentrations of $NO_3-N\;and\;PO_4-P$. The carbon bio-mass and $chlorophyll-{\alpha}$ concentration related to diatom- and dinoflagellate cell densities and these were affected by flagellate cell density, salinity, and concentrations of $SiO_2-Si\;and\;PO_4-P$. Last six years monitoring data in Masan city obtained from Korean Meteorological Agency indicates gradual increase in air temperature. And the precipitation decreased especially in spring season. The winter bloom found in 2003 may be caused by the increase in the temperature and this bloom subsequently induced the nutrients depletion, which continued until next spring probably due to no precipitation. Therefore, the spring bloom, which had been usually observed in the bay, might disappear in 2004.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.1
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• pp.1-14
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• 2008

Eight comprehensive oceanographic cruises on a squared $30{\times}30\;km$ area have been made to investigate the short and long-term impacts on the water qualities due to the sand mining operations at Exclusive Economic Zone (EEZ) in the central Yellow Sea from 2004 to 2007. The area was categorized to 'Sand Mining Zone', 'Potentially Affected Zone', and 'Reference Zone'. The investigation covered suspended solids, nutrients (nitrate, nitrite, ammonium, phosphate), and chlorophyll-a in seawater and several parameters such as water temperature, salinity, pH, and ORP. Additionally, several intensive water collections were made to trace the suspended solids and other parameters along the turbid water by sand mining activities. The comprehensive investigation showed that suspended solids, nitrate, chlorophyll-a and ORP be sensitively responding parameters of seawater by sand mining operations. The intensive collection of seawater near the sand mining operation revealed that each parameter show different distribution pattern: suspended solids showed an oval-shaped distribution of the north-south direction of 8 km wide and the east-west direction of 5 km wide at the surface and bottom layers. On the other hand, phosphate showed so narrow distribution not to traceable. Also ammonium showed a limited distribution, but its boundary was connected to the high nitrate and chlorophyll-a concentrations with high N/P ratios. From the last 4 years of the comprehensive and intensive investigations, we found that suspended solids, ammonium, nitrate, chlorophyll-a, and ORP revealed the sensitive parameters of water quality for tracing the sand mining operations in seawater. Especially suspended solids and ORP would be useful tracers for monitoring the water qualities of remote area like EEZ in Yellow Sea.

• Journal of Mushroom
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• v.22 no.2
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• pp.60-66
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• 2024

This study was conducted to selection and investigate appropriate conditions for mass production of antagonistic microbes to control cobweb disease caused by Cladobotryum mycophilum. A grampositive bacterium was isolated from spent substrate of Agaricus bisporus and showed significant antagonistic activity against Cladobotryum mycophilum. The bacterium was identified as Bacillus altitudinis. based on the cultural, biochemical and physiological characteristics, and 16S rRNA sequence. The isolate is saprophytic, but not parasitic nor pathogenic to cultivated mushroom whereas it showed strong inhibitory effects against C. mycophilum cells in vitro. The control efficacy of B. altitudinis HC7 against cobweb disease of C. mycophilum was up to 78.2% on Agaricus bisporus. The suppressive bacterium may be useful for the development of biocontrol system. To define the appropriate conditions for the mass production of the Bacillus altitudinis HC7, we have investigated appropriate culture conditions and effects of various nutrient source on the bacterial growth. The appropriate initial pH and temperature were determined as pH 6.0 and 30℃, respectively. The appropriate concentration of medium elements for the growth of pathogen inhibitor bacterium(Bacillus altitudinis HC7) was determined as follows: 3.0% soluble startch, 10% soytone, 1.0% (NH₄)₂HPO₄, 1.0 mmol KCl, and 0.5% L-asparagine.

• Food Science and Preservation
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• v.30 no.6
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• pp.1012-1028
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• 2023

The findings of this study confirmed the alteration of β-glucosidase activity, nutritional constituents, isoflavones, antioxidant activities, and digestive enzyme inhibition activities in soybeans during solid-state fermentation times with mycelia of Tricholoma matsutake. After nine days, the highest activity level was observed for β-glucosidase (3.90 to 38.89 unit/g) and aglycones (163.03 to 1,074.28 ㎍/g). The sum of isoflavones showed a significant decrease (3,489.41 to 1,325.66 ㎍/g) along with glycosides (2,753.87 to 212.43 ㎍/g) for fermentation, while fatty acids showed a slight increase and amino acids showed a marked increase. Total phenolic and flavonoid contents showed a corresponding increase according to fermentation times (5.58 to 15.09 GAE mg/g; 0.36 to 1.58 RE mg/g). Antioxidant and enzyme inhibition activities also increased; in particular, the highest level of scavenging activities was observed for ABTS (up 60.13 to 82.08%), followed by DPPH (up 63.92% to 71.98%) and hydroxyl (up 36.01 to 52.02%) radicals. Of particular interest, α-glucosidase (6.69 to 83.49%) and pancreatic lipase inhibition (1.22 to 77.43%) showed a marked increase. These results demonstrated that fermentation of soybeans with the mycelia of T. matsutake enhanced the nutritional and functional constituents, and the biological activities of soybeans. Thus, this fermentation technology can be used to produce a novel functional materials from soybeans.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.422-430
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• 2023

The nutrient-rich and climate-resilient finger millet (Eleusine coracana (L.) Gaertn.) is a relatively new crop on the agricultural landscape. The present study explores the agronomic characteristics and antioxidant activities of grains and cookies produced from 'Finger1ho,' which was the first finger millet variety developed in South Korea. With heightened calcium content (314 mg/100 g) and polyphenol levels, 'Finger1ho' exhibited superior radical scavenging activities compared to other millets. The investigation assessed the impact of whole finger millet flour at varying concentrations (0, 10, 30, 50, and 100%) on cookie properties. Increasing the substitution of finger millet flour in the cookie formulation resulted in a notable rise in calcium content, ranging from 1.8 times at 10% to an impressive 10.8 times at 100%, surpassing the levels found in conventional wheat cookies. Conversely, the sodium (Na) levels in finger millet cookies demonstrated minimal variations, presenting a potentially favorable aspect in addressing the high Na intake prevalent in the South Korean diet. Notably, the antioxidant activity, assessed through ABTS and DPPH radical scavenging assays, exhibited a significant elevation compared to the control. This increase in antioxidant activity was directly proportional to the quantity of finger millet incorporated (p<0.001), indicating the potential health benefits associated with higher levels of finger millet in the cookie formulation. This study highlights finger millet's potential as a beneficial ingredient, enhancing both consumer acceptability and the functional attributes of cookies. Notably, cookies with 10% to 50% added finger millet exhibited significantly superior quality characteristics compared to controls, suggesting promising avenues for health-functional cookie development.

• Journal of The Korean Society of Grassland and Forage Science
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• v.44 no.1
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• pp.1-5
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• 2024

Understanding changes in fermentation characteristics and microbial populations of forage silage during ensiling is of interest for improving the nutrient value of the feed for ruminants. This study was conducted to investigate the changes in fermentation characteristics and bacterial communities of whole crop rice (WCR) silage during the ensiling period. The chemical compositions, pH, organic acids and bacterial communities were evaluated at 0, 3, 6, and 12 months after ensiling. The bacterial communities were classified at both the genus and species levels. The dry matter content of WCR silage decreased with the length of storage (p<0.05), but there was no significant difference in crude protein and NDF contents. Following fermentation, the pH level of WCR silage was lower than the initial level. The lactic acid content remained at high levels for 3 to 6 months after ensiling, followed by a sharp decline at 12 months (p<0.05). Before fermentation, the WCR was dominated by Weissella (30.8%) and Pantoea (20.2%). Growth of Lactiplantibacillus plantarum (31.4%) was observed at 3 months after ensiling. At 6 months, there was a decrease in Lactiplantibacillus plantarum (10.2%) and an increase in Levilactobacillus brevis (12.8%), resulting in increased bacteria diversity until that period. The WCR silage was dominated by Lentilactobacillus buchneri (71.2%) and Lacticaseibacillus casei (27.0%) with a sharp reduction in diversity at 12 months. Overall, the WCR silage maintained satisfactory fermentation quality over a 12-month ensiling period. Furthermore, the fermentation characteristics of silage were found to be correlated to bacterial microbiome.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.4
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• pp.31-37
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• 2010

Livestock manures have a potential to be a valuable resource with an efficient treatment. In Korea, 42 million tons of livestock manure were generated in 2008, and 84 % of them were used for compost and liquid fertilizer production. Recently recycling of livestock manure for biogas production through anaerobic digestion is increasing, but its utilization in agriculture is still uncertified. In this study, there was applied co-digestate to the paddy for rice cultivation based on N supplement. Co-digestate was fertilizer fermented with pig slurry and food waste combined with the ratio of 70:30(v:v) in its volumetric basis. For assessing the safety of co-digestate, it was monitored the contents of co-digestate for seasonal variation, resulted in no potential harm to the soil and plant by heavy metals. The results showed that soil applied with co-digestate was increased in exchangeable potassium, copper and zinc mainly due to the high rate of pig slurry in co-digestate applied. Considering high salt content due to the combination with food waste, strict quality assurances are needed for safe application to arable land though it has valuable fertilizer nutrient. Leachate after treatment showed that the concentration of nitrate nitrogen washed out within two weeks. Considering the salt accumulation results in soil, it is highly recommended that the application rate of co-digestate should not exceed the crop fertilization rate based on N supplement. With these results, it was concluded that co-digestate could be used as an alternative fertilizer for chemical fertilizer. More study is needed for the long-term effects of co-digestate application on the soil and water environment.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.434-441
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• 2023

Determining the size or area of a plant's leaves is an important factor in predicting plant growth and improving the productivity of indoor farms. In this study, we developed a convolutional neural network (CNN)-based model to accurately predict the length and width of lettuce leaves using photographs of the leaves. A callback function was applied to overcome data limitations and overfitting problems, and K-fold cross-validation was used to improve the generalization ability of the model. In addition, ImageDataGenerator function was used to increase the diversity of training data through data augmentation. To compare model performance, we evaluated pre-trained models such as VGG16, Resnet152, and NASNetMobile. As a result, NASNetMobile showed the highest performance, especially in width prediction, with an R_squared value of 0.9436, and RMSE of 0.5659. In length prediction, the R_squared value was 0.9537, and RMSE of 0.8713. The optimized model adopted the NASNetMobile architecture, the RMSprop optimization tool, the MSE loss functions, and the ELU activation functions. The training time of the model averaged 73 minutes per Epoch, and it took the model an average of 0.29 seconds to process a single lettuce leaf photo. In this study, we developed a CNN-based model to predict the leaf length and leaf width of plants in indoor farms, which is expected to enable rapid and accurate assessment of plant growth status by simply taking images. It is also expected to contribute to increasing the productivity and resource efficiency of farms by taking appropriate agricultural measures such as adjusting nutrient solution in real time.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.3
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• pp.31-41
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• 2024

Food waste compost with high salt content produced by aerobic digestion, but concerns about application of cropland. To address this issue, food waste is being composted by mixing it with livestock manure, which has a lower salt content. Therefore, this study aimed to evaluate the growth characteristics of red pepper and soil chemical properties for continuous application with different amounts of food waste compost with manure (FWC). Treatments were consisted of no fertilizer (NF), inorganic fertilizer (N-N-P₂O₅-K₂O, 19.0-11.2-14.9 kg 10a^-1), and inorganic fertilizer + food waste compost with manure (NPKFWC). FWC treatment was applied at three treatment rates based on soil organic matter content: 900 kg 10a^-1, 1,800 kg 10a^-1, and 2,700 kg 10a^-1 ( referred to a s FWC 1, 2, 3 , respectively). As a r esult of the red pepper yield was about 1.8 times higher in NPKFWC 1 and NPKFWC 2 than that in the NF, but decreased in the NPKFWC 3, 300% of the recommended FWC application rate. Yield decreased in all FWC treatments with continuous application for three year and also decreased about 40% from 3,265 kg 10a^-1 in the first year to 1,948 kg 10a^-1 in the third year. For the soil chemical properties, the content of soil organic matter, available P₂O₅, and exchangeable cations increased in the FWC treatments, and were higher than the NF. Exchangeable sodium in all treatments was increased slightly compared to the soil before used, and no significant salinization was observed in the FWC. This study confirmed that excessive use of FWC not only reduced nutrient use efficiency, but also decreased the red pepper yield. Therefore, it is concluded that optimum usage of FWC is effective for agroecological impacts.