• Journal of Aquaculture
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• v.20 no.1
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• pp.31-40
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• 2007

To find out the effect of the spat planting time and environmental factors in the arkshell, Scapharca broughtonii (Schrenck), we investigated the growth, survival rate of arkshell and habitat characteristics in Gamak Bay, Yeoja Bay and Saryang Island. We planted artificial spats of arkshell in Gamak Bay and Yeoja Bay at November 2004, and also planted domestic and Chinese natural spats in Saryang Island at March 2005. We measured growth, survival rate of arkshell, physiochemical parameters of the water mass (water temperature, salinity, dissolved oxygen, nutrients and chlorophyll a) and characteristics of the sediment (oxygen penetration depth, oxygen microprofiles, ignition loss and chemical oxygen demand) by monthly. The cumulative survival ratio of arkshell in Gamak Bay was the highest at December, whereas the ratio of arkshell in Yeoja Bay was recorded as 0% at October. The monthly growth rates of arkshell length in Gamak Bay and Yeoja Bay were the highest in May and the growth rate of the Korean arkshell in Saryang Island was higher than Chinese ones significantly. The high mortality (> 65%) of the arkshell in Yeoja Bay during summer probably caused by high water temperature, inflow of low salinity water, and low dissolved oxygen concentration in sediment. The concentrations of nutrient and sediment COD were considered to play an important role in the monthly survival ratio of arkshell in Gamak Bay and Sarayng Island. We suggest that the growth and mortality of arkshell might be influenced to the planting time of spat and the habitat characteristics.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.525-534
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• 2005

A column experiment was performed to investigate the influence of the sludge cake development on the riverbed and the hydraulic gradient imposed by the drawdown at the well on the filtrate quality in order to offer a guideline in the design and operation of the riverbed filtration. Results show that the sludge cake on the riverbed plays an important role in the removal of the organic matter. Under the conditions of this study the COD removal rate increased from 17% to 50% along with the sludge cake development, which was equivalent to the BCOD removal of 22% and 67%, respectively. The active removal of the organic matter took place in the sludge cake and the upper 40 cm of the riverbed. As the flow rate increased owing to the increase in the head difference imposed on the column, the slope of the COD profile near the column inlet decreased, however, the profiles converged in about 40 cm from the inlet. In 10 days of sludge cake formation the dissolved oxygen was depleted at the depth of 70 cm, which suggests the denitrification can take place beyond the depth. This depth was further reduced to $20{\sim}40\; cm$ as the sludge cake developed. From this study the removal of organic matter can be expected through the riverbed filtration even with the depth of as shallow as 3 m, which is frequently met in Korea, while the removal of nitrogen through denitrification is not expected to be active under the condition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.1
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• pp.52-61
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• 2000

The field surveys and the seawater analyses were conducted over the southern waters of Cheju island every month from July 1997 to June 1988. The distributions of dissolved inorganic nitrogen(DIN), dissolved inorganic phosphorus(DIP), chemical oxygen demand(COD) and dissolved oxygen(DO) in the southern water area of Cheju island were simulated and reproduced by an ecosystem model. In order to estimate the environmental capacity of the southern coastal area of Cheju island, the simulations for predicting the situation of unfavorable environment in which marine water quality might not be satisfied with Korean standards were performed with an ecosystem model by controlling quantitatively the pollution loads of discharge sources including streams flowing into the sea. The more the loads of 4 major pollution sources flowing into model region increase, the more evident appear the increases of COD, DIN and DIP concentrations around the water areas adjacent to pollution sources. In case the pollution loads of all 4 discharge sources including streams become 3 times as high as the present loads, the concentration of DIN at near-shore waters appears to be increased to about 14.5mmol/m³(=0.20mg/ℓ) which is the third class criterion of Korean standards for marine water quality. In case of 10 times as high as the present loads, COD at near-shore waters appears to be increased to about 1.0mg/ℓ which is the first class criterion of Korean standards. In case of 20 times as high as the present loads, DIP at near-shore waters appears to be increased to about 0.50mmol/m³(=0.015mg/ℓ) which is the second class criterion of Korean standards.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.761-766
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• 2020

Phenylamine derivatives are substances that have a biochemical action and are widely applied as psychotropic drugs. In particular, with regard to the quantitative analysis of substances such as ephedrine, amphetamine, pentermine, and dopamine, many previous studies such as electrochemical, vacuum ultraviolet method, and gas chromatography have been conducted. However, there have not been many studies on the structural characteristics of molecular units. Therefore, In this study, we used (HyperChem8.0's, HC) semi-empirical PM3 method to calculate the total energy, band gap, electrostatic potential, and net charge of ephedrine, amphetamine, pentamine and dopamine to investigate the chemical properties of each derivative according to the molecular structure change. The results showed that for total energy -43,171.8, -32,9538.3, -36,407.3 and -43,061.2 Kcal/mol, respectively, while for band gaps, 10.16379377, 9.9531666, 9.7878002 and 9.0589282 eV. Also, for electrostatic potentials, 1.301~-0.045, 1.694~0.299, 0.694~-0.158 and 1.587~-0.048 respectively. Finally, looking at the distribution of net charges, the oxygen atoms, nitrogen atoms and carbon atoms were -0.312~-0.242, -0.161~-0.051 and +0.13~-0.12 respectively. These results are expected to lead to chemical action centered on phenyl radicals and oxygen and nitrogen atoms common to phenethylamine derivatives.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.251-259
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• 2016

This study examined the DO concentration distribution and ORP distribution using microbubbles on pilot-scale aeration tanks. As a result of MLSS mixing and oxygen transfer phenomenon using microbubbles, different DO concentrations were observed depending on the circulation of the liquid with the microbubble supply location on the lateral of an aeration tank. The simulation results of CFD (computational fluid dynamics) program showed that MLSS mixed with a microbubble supply in the middle the reactor is much better than on the left side of the reactor. A single reactor containing an anaerobic, anoxic, and aerobic zone, was evaluated without partition according to the location of the microbubble supply based on the experiments and CFD analysis. MLSS was separated into solid-liquid by the microbubble supply in the aeration tank. Consequently, selecting the appropriate microbubble size is important for MLSS mixing and was maintained at the proper DO concentration for biological treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.506-510
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• 2013

This study aimed to understand relationship between potential risky species and environmental factors at ports in Korea. During the study periods, 25 potential risky species (red tide and toxic species) representing 20 red-tide species, 5 toxic species were observed in the all ports. Skeletonema costatum (red-tide species) was predominated in all study area. This species showed positive correlation with pH, while negative correlation with dissolved oxygen (p<0.05) at Busan port. Also, this species showed positive correlation with total suspended solids and pH (p<0.05) at Ulsan port. However, Sk. costatum showed positive correlation with nitrate at Incheon port (p<0.01). Pseudo-nitzschia spp. producing amnesic shellfish poison (domoic acid) showed positive correlation with nitrate and silicate in all study areas (p<0.05). Alexandrium spp. (paralytic shellfish poison) and Dinophysis acuminata (diarrhetic shellfish poison) were affected by chemical oxygen demand (p<0.01). Our results indicated that red-tide species were affected by physical factors, while chemical factors affected toxic species.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.1-7
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• 1996

Three formulations were used to prepare the cellulose-based edible films consisting of hydrocolloid and lipids; film A made by coating method, films B and C by emulsion method, which were formed in a thin layer glass plate and then dried. Films A, B and C were all approximately 0.03 mm thick with 1-3% moisture, 59-68% lipid, and almost whitish color. Film A was better in tensile strength, and lipids affected water vapor permeability on three films, in which films A and B did not differ significantly. Water vapor permeability of film A did not change but those of films B and C decreased significantly after storage for 8 weeks at $-15^{\circ}C$. Oxygen transmission rate and oxygen permeability of films A and C did not differ and changed significantly after 8-week storage at $-15^{\circ}C$. Under scanning electron microscope (SEM) observation on the structural characteristics of each film, film A indicated relatively uniform and smooth surface coatings of beeswax, while films B and C had individual lipid crystals and could be discerned. As a result, film A was better than films B and C in respect of physical properties, but the selection of useful film depended upon which physical property was more functional. Moreover, it was desirable in some cases for using films B and C because of their easiness of preparation and cold storage durability. It will be further needed to investigate how to formulate films B and C to have more unique surface characteristics, and to reduce water vapor and oxygen transmission rates.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.566-572
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• 2017

For four times, zooplankton collection were conducted seasonally in October 2015-July 2016 at five sites located in the wet lands of the lower Han River, ie., Si-am, Sung-dong, Gong-reung stream, San-nam and Jang-hang. A total of 46 species of zooplankton were collected, which comprise 25 species of rotifers, seven cladocerans, ten copepods, and one species of nematod, ostracod and decapod, respectively. No brackish and marine species were distributed except for two species of brackish water copepods. Prosperity in the species number of 15 species was observed in October at Sung-dong and Jang-hang. The maximum abundance was recorded in March at Si-am with $8,000indiv.\;L^{-1}$ with the explosion of Brachionus calyciflorus. Other sites also showed high abundances in March with the abundance higher than $5,000indiv.\;L^{-1}$. Except in March, the abundance levels were recorded as less than some hundred $indiv.\;L^{-1}$ throughout the study. Species diversity varied between 0.4-1.8. The gut contents of the copepodite showed that various diatoms might be their major food items, and lots of unidentified materials were also observed. The environmental conditions of water temperature, pH and dissolved oxygen content showed to vary $10.1-28.2^{\circ}C$, 7.1-8.6 and $4.5-11.0mg\;L^{-1}$, respectively.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.322-329
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• 2018

In this study the community characteristics of benthic macroinvertebrates distributed in stream of Gaya Mountain were figured out and the correlation with the physicochemical water quality factors were calculated. During the study period, total 4 phyla, 6 classes, 13 orders, 36 families, 100 species of benthic macroinvertebrates were recorded. Ephemeroptera were the most dominant followed by Trichoptera, Plecoptera, Diptera, Non-insecta, Hemiptera, and Odonata. The overall dominant species was Cincticostella levanidovae by dominance rate in 17.72%, subdominant species was Hydatophylax nigrovittatus by dominance rate in 6.15%. The biotic indices showed the diversity index 5.17, richness index 12.44, dominant index 0.24 and evenness index 0.78, there is no absolutely dominant benthic macroinvertebrates in the stream of Gaya Mountain. We identified the correlation between the species number and individuals of main taxa and the physicochemical water quality factors. Ephemeroptera and Plecoptera showed a negative correlation with water temperature, but they represented a positive correlation with the dissolved oxygen. This results suggest that water temperature and dissolved oxygen are important physicochemical water quality factors affects the distribution of Ephemeroptera and Plecoptera, the indicators of clean water stream.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.250-257
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• 2023

Glutamate is an excitatory neurotransmitter distributed in the central nervous system of mammals. However, high concentrations of glutamate are known to cause neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and stroke by causing nerve cell death. In this study, the antioxidant activity and neuroprotective effect of subtropical natural products were analyzed. Among 11 subtropical plant extracts mainly tested, Sallacca wallichiana extract (SE) showed the greatest free radical scavenging activity. Then, we confirmed through WST-1 assay that SE protected HT22 cells against glutamate-induced cell death in a concentration-dependent manner. The protective effects of SE against glutamate-induced apoptosis in HT22 cells were also confirmed by flow cytometry analysis using Annexin V/PI double staining. We also confirmed using H₂DCF-DA single staining that SE inhibits glutamate-induced intracellular reactive oxygen species. And we were confirmed through that SE inhibited glutamate-induced phosphorylation of Mitogen-activated Protein kinases. Consequently, our results propose that SE may contribute to the development of therapeutics to prevent neurodegenerative diseases.