• Korean Journal of Environmental Biology
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• v.26 no.4
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• pp.292-302
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• 2008

The purpose of this study was to analyze the trophic structures and the energy flows in the lower reaches of the Nakdong River using the Ecopath model (Walter et al., 1997). The sampling and analyses were carried out at 6 sampling sites of the lower reaches of the Nakdong River on May and November in 2007. Total of 9 groups detritus, macrophytes, phytoplankton, zooplankton, zoobenthos, Cyprinus carpio, Hemibarbus labeo, Micropterus salmoides and other fishes were considered to assess the trophic relationship, energy flows and interactions among them in the study. As a result, it was concluded that the lower reaches of the Nakdong River was consisted of producers (Detritus, Macrophytes, Phytoplankton), primary consumers (Zooplankton, Zoobenthos, Cyprinus carpio, Hemibarbus labeo, Other fishes) and secondary consumer (Micropterus salmoides). The total system throughput was estimated at 2.7 kg m$^{-2}$ year$^{-1}$ including a consumption of 52%, exports of 9.1%, respiratory flows of 18.0% and flows into detritus of 20.9%. MTI (mixed trophic impacts) analysis demonstrated that Pseudobagrus fulvidraco had positive impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. On the other hand, other fishes had negative impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. Also, all the functional groups except detritus had a negative impact on themselves.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.165-171
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• 2010

The Homogeneous Charge Compression Ignition (HCCI) engine concept allows for both NOx and particulate matter to be reduced simultaneously, and it is a promising way to meet the next environmental challenges. Unfortunately, HCCI combustion often increases CO and HC emissions. The development of oxidation catalyst (OC) requires high conversion efficiency for CO and HC at low temperature. Conventional oxidation catalyst technologies may not be able to convert these emissions because of the saturation of active catalytic sites. The OC used in this study was 600 cpsi cordierite. Three kinds of OC with different amounts of Pt and Pd were used. The influence of the space velocity (SV), $H_2O$ and $O_2$ concentration was also studied. All types of OCs were found to have over 90% CO conversion efficiencies at $170^{\circ}C$. When in the presence of water vapor, CO conversion was increased, but $C_3H_8$ conversion was decreased. The performance of the OC was not influenced by initial the HC concentration. The 2Pt/Pd catalyst was better in terms of thermal aging than the Pt-only catalyst. The $LOT_{50}$ of both fresh and aged OC was increased with increasing SV and with the presence of $H_2O$.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1621-1629
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• 2008

Harmful algal blooms (HABs), commonly called red tides, are caused by some toxic phytoplanktons, and have made massive economic losses as well as marine environmental disturbances. As an effective and environment-friendly strategy to control HAB outbreaks, biological methods using marine bacteria capable of killing the harmful algae or algicidal extracellular compounds from them have been given attention. A new member of the $\gamma$-Proteobacteria, Hahella chejuensis KCTC 2396, was originally isolated from the Korean seashore for its ability to secrete industrially useful polysaccharides, and was characterized to produce a red pigment. This pigment later was identified as an alkaloid compound, prodigiosin. During the past several decades, prodigiosin has been extensively studied for its medical potential as immunosuppressants and antitumor agents, owing to its antibiotic and cytotoxic activities. The lytic activity of this marvelous molecule against Cochlodinium polykrikoides cells at very low concentrations ($\sim$l ppb) was serendipitously detected, making H. chejuensis a strong candidate among the biological agents for HAB control. This review provides a brief overview of algicidal marine bacteria and their products, and describes in detail the algicidal characteristics, biosynthetic process, and genetic regulation of prodigiosin as a model among the compounds active against red-tide organisms from the biochemical and genetic viewpoints.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.588-597
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• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.58-63
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• 2000

Objectives: To demonstrate effective diagnostic method and proper management of recurrent thyroid cancer through to compare treatment and surveillance of $I^{131}$ scanning detected recurrence and clinically detected recurrence. Material and Methods: We retrospectively analyzed clinical information about 46 patients who has recurrent thyroid cancer of 298 patients who have been primarily operated due to thyroid cancer in PMC at the over 10 years between 1986 and 1995. We examine incidence of recurrence due to pathologic types, site of recurrence, disease free interval, detection method of recurrence, and also treatment and progression of recurrence. A patients in which the clinical examination was entirely negative and the $I^{131}$ scan demonstrated either a new area of $I^{131}$ uptake or an increased area of concentration, compared to the previous scan, was designated as a recurrence detected by $I^{131}$ scan only. Recurrences that were obviously by physical examination or chest x-ray, etc were considered clinically detected recurrence, regardless of the the results of the thyroid scan. Results: Mean of disease tree interval(DFI) is 36months. When mean DFI of $I^{131}$ scan detected recurrence is 28months, whereas mean DFI of clinically detected recurrence is 47months. In statiscal analysis, p-value is 0.043 as significantly. In progression of recurrent patient, NED is 28case, AWD is Sease, DOD is 13case. Among the 13case, scan detected recurrence is lease of 20 patients(5%), whereas clinically detected recurrence is l2case of 26 patient(46%). In statiscal analysis, p-value is 0.003 as significantly. Conclusion: Early detection of the recurrent thyroid cancer by $I^{131}$ scanning leads to good progress compare with detection by clinical examination. NED: No Evidence of Disease AWD : Alive With Disease DOD : Dead Of Disease DOC: Dead of Other Cause

• Journal of Wetlands Research
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• v.11 no.3
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• pp.145-151
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• 2009

Recently the water quality management policy has been changed from managing the point source to controlling the nonpoint sources (NPSs) because of TMDL program. Most NPSs are accumulated on the surface during dry periods. These accumulated pollutants are washed-off during a storm event and highly impairing the water quality of the receiving water bodies. Usually NPS has high uncertainty and is hard to control because of the variability of the rainfall and watershed characteristics. Also, NPS is derived from various land uses. The Ministry of Environment (MOE) is studying and monitoring the pollutant loads from each land use since 2007 to determine the unit pollutant loads. This research was a part of long-term monitoring program conducted to characterize the washoff and provide the mean EMC of artificial grassland. The average EMCs result of BOD, COD, DOC, SS, TN, NH4-N, NO3-N, TP, and PO4-P of the artificial grassland were deterined to 8.2, 17.5, 11.3, 110.1, 3.07, 0.20, 0.75, 0.86 and 0.08 mg/L, respectively. The results of statistical analysis conducted showed a low correlation to the contaminants.

• Biomedical Science Letters
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• v.8 no.4
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• pp.235-244
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• 2002

This study was carried out to determine the blood and milk progesterone by enzyme-linked immunosorbent assay (ELISA), and milk urea nitrogen (MUN) in cows. MUN and protein concentration were determined using automated infared procedures. The optimum conditions of ELISA system was investigated including the first and second antibody titres, bound percent, and enzyme conjugate and also the factors on MUN and protein concentration by sampling procedures and addition of preservatives. Progesterone antibodies did not react to pregnenlone, testosterone, estrone, estradiol-l7$\beta$, aldosterone, cortisol, corticosterone and 11$\alpha$-dehydroxycortisone (DOC), but reacted with only progesterone. The intra and inter-assay coefficient of variation 4.5%, 6.1~9.4% when used of bovine serum. The morning, MUN concentration (17.6$\pm$2.8 mg/100 ml) in the 13 herds was similar to that of evening MUN concentration of the lactating cows from the same herd. A significant relationship between morning and evening milk samples of upper parameters was found r=0.93. Difference in MUN concentration with sampling procedures and using of preservatives were investigated.

• Korean Journal of Microbiology
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• v.35 no.1
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• pp.35-40
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• 1999

Effects of different molecular size fractions (100,000 nMW-0.1 $\mu\textrm{m}$m, 10,000 nMW-100,000 nMW and 1,000 nMW-'L0,000 nMW) of dissolved organic matter on the bacterial numbers and $\beta$-glucosidase activities in Lake Soyang were investigated. Even though the concentrations and characteristics of each fractions were different, bacterial growth curves of each fractioii were Lypical and similar. Each growth curve had highest peak of $1.1{\times}10^{7}$ cells $ml^{-1}$. But, the $\beta$-lucosidase activitics of each fraction were quite different. In high molecular weight fraction (HMW: 100,000 nMW-0.1 $\mu\textrm{m}$m), Vmax of Pglucosidase activity ranged from 550 to 1,160 nmol $1^{-1}$.$hi^{-1}$, but in low molecular weight f~action (1,000 nMW-10,000 nMW), that ranged from 1 to 14 om01 1$^[-1}$${-1}$

• The Korean Journal of Ecology
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• v.18 no.1
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• pp.1-15
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• 1995

Alakline phosphatase activity (AP A) as a phosphorus deficiency measurement in flowing waters and of microhabitats (rocks, wood, leaves, and sediments) was measured and its relationship to flux of nutrients and response to rainfall events were determined for two geologically different streams in west Alabama from August to November. Results indicated water column AP A in both streams had a low correlation with levels of orthophosphate, total organic phosphorus, nitrate, ammonia, dissolved organic carbon, and discharge (r=0.075-0.583; n=g-IU. Communities on rock surfaces showed a higher AP A level than those on wood and leaves. Sediment passed through a $106{\mu}m$ sieve showed 2-9 times higher AP A level than material passed through $425{\mu}m$ sieve. The first storm after drought at Yellow Creek introduced substantial quantities of DOC (2.5 times baseflow concentrations) and $N0_3-N$ (5.8 times baseflow concentrations) which did not affect AP A significantly. The second storm at Little Schultz Creek caused minor changes in nutrient cocentrations; however $N0_3-N$ levels and AP A were drastically lower due to the dilution effect. Retention of stream water AP A at Yellow Creek and Little Schultz Creek on $0.45{\mu}m$ filter (54 and 43%, respectively) and $0.22{\mu}m$ (83 and 77% of total APA. respectively) indicated more free dissolved portion of the enzyme was present at Little Schultz Creek. Little Schultz Creek (with carbonate and with a higher productivity and biomass) showed a consistantly greater AP A activity $(132{\pm}54\;{\mu}M{\cdot}1^{-1}{\cdot}min^{-I};\;n=g)$ than Yellow Creek $(41{\pm}23\;{\mu}M{\cdot}1^{-I}{\cdot}min^{-I}$, with a sandstone substrate; n=l1, $p{\leq}O.OO1)$. Overall, a greater APA on all microhabitats and the presence of more dissolved enzyme in Little Schultz Creek during the study period may indicates it is more P deficient than Yellow Creek.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.246-254
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• 2017

Microcystin-LR (MC-LR) is one of most abundant microcystins, and is derived from blue-green algae bloom. Advanced oxidation processes (AOPs) are effective process when high concentrations of MC-LR are released into a drinking water treatment system from surface water. In particular, UV-based AOPs such as UV, $UV/H_2O_2$, $UV/O_3$ and $UV/TiO_2$ have been studied for the removal of MC-LR. In this study, UV-LED was applied for the degradation of MC-LR because UV lamps have demonstrated some weaknesses, such as frequent replacements; that generate mercury waste and high heat loss. Degradation efficiencies of the MC-LR (initial conc. = $100{\mu}g/L$) were 30% and 95.9% using LED-L (280 nm, $0.024mW/cm^2$) and LED-H (280 nm, $2.18mW/cm^2$), respectively. Aromatic compounds of natural organic matter changed to aliphatic compounds under the LED-H irradiation by LC-OCD analysis. For application to raw water, the Nak-dong River was sampled during summer when blue-green algae were heavy bloom in 2016. The concentration of extracellular and total MC-LR, geosmin and 2-MIB slightly decreased by increasing the LED-L irradiation; however, the removal of MC-LR by UV-LED (${\lambda}=280nm$) was insufficient. Thus, advanced UV-LED technology or the addition of oxidants with UV-LED is required to obtain better degradation efficiency of MC-LR.