• Food Science and Preservation
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• v.24 no.2
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• pp.221-229
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• 2017

The effect of sweet potato on the quality of Doenjang was investigated during fermentation. Viable cells of yeast decreased gradually after 4 weeks of fermentation, but those of aerobic bacteria increased in the late stage. Amylase activity of Doenjang was higher in the late stage of fermentation, while neutral protease maintained high activity during fermentation. Hunter L and b values of Doenjang decreased gradually during fermentation, while a value was increased. The pH of Doenjang decreased gradually until 10 weeks of fermentation, and the titratable acidity was low in the sweet potato added groups. The acid value was low in the Shinyulmi sweet potato added Doenjang. Water activity and oxidation-reduction potential of Doenjang decreased during fermentation. Reducing sugar of Doenjang decreased in the middle stage of fermentation, and it was low in sweet potato added groups. The alcohol content of Doenjang decreased after 2 weeks of fermentation. Amino and ammonia-type nitrogen of Doenjang increased during fermentation and reached the maximum after 10 and 12 weeks of fermentation, respectively. After 12 weeks fermentation, 8% of Shinyulmi sweet potato added Doenjang was more favorable taste, flavor and overall acceptability (p<0.05) than the control or the Yeonwhangmi sweet potato added groups.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.377-386
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• 2015

The purpose of this research was to suggest the water quality improvement in streams by evaluating the distribution characteristics of organics and ammonia nitrogen discharged by pollution sources from human living. The public sewage treatment plants'(PSTPs) effluents and the waters from streams in Gyeonggi-do were sampled and analyzed. Nitrogenous oxygen demand (NOD) was measured for the stream waters as well as the PSTPs effluents, and the correlations of NOD and $NH_3$-N, $NH_3$-N and water temperature in the PSTPs effluents were confirmed. In the case of the stream waters, the ratios of NOD to BOD and $NH_3$-N increased in the downstream sites after discharging the PSTPs effluents. As a result of statistical analysis of $NH_3$-N concentrations for the national water quality monitoring streams in Gyeonggi-do, $NH_3$-N showed the non-normal distribution which were biased to the left, but showed the considerable level because of higher coefficient of variation. Therefore, it is required to establish the water quality standard for the $NH_3$-N as a new parameter for judging the quality of the streams. In addition, inducing complete nitrification and introducing a logical standard setting system are needed to improve the water quality of streams by identifying distribution of the nitrogen components from PSTPs effluents.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.171-178
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• 2007

This study was carried out to investigate the effect of microbial complex diets on improvement of air quality in finishing pig building. Ammonia and hydrogen sulfide concentrations were significantly(p<0.05) decreased by dietary supplementation of 0.1% level of microbial complex compared with those of control according to the time in the finishing pig building. Characteristics of piggery liquid slurry that total nitrogen and $NH_3-N$ of treatment were reduced relatively compared with those of control, and were decreased depending on the time. In conclusion, the result obtained from this study suggest that the dietary supplementation of microbial complex for finishing pigs may improve environment in the finishing pig building.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.8-18
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• 2019

The objectives of this study were to analyze the influence of chemical water quality on fish guilds, pollution tolerance and the multi-metric ecological health, based on the Fish Assessment Index (FAI) in the main stream of Mangyeong River between 2009-2016. The quality of water with specific conductivity, TP, and $NH_4-N$ got worse dramatically in the down region. During the study, a total of 50 species were collected and the most dominant species was Zacco platypus. Also known as tolerant species, accounted 22.9% of the total abundances, thus indicating a trophic degradation. The downstream region (S5) had the highest number of fish external abnormalities, indicating a degradation of ecological health, based on the fish assemblages. Pearson correlation analysis indicated that relative abundance of tolerant fish species and omnivore fish species had a significant positive correlation(r>0.30, p<0.05) with values of BOD, conductivity and $NH_4-N$. Whereas, the relative abundance of the sensitive species and insectivore species had a significant negative relations (r<-0.30, p<0.001) with the parameters. The mean obtained from the multi-metric fish model, based on the FAI of all sites was 47 (n=40). This indicated a "fair condition" in the ecological health, and the downstream regions (S3-S5) were judged as "bad condition", indicating an influence of the chemical degradation on the ecological health.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.411-422
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• 2004

A limnological survey was conducted in a reservoir, Lake Hoengsung located in Kangwondo, Korea, from July 2000 to September 2001 on the monthly basis. Phosphorus loading from the watershed was estimated by measuring total phosphorus concentration in the main tributary. Secchi disc transparency, epilimnetic (0-5 m) turbidity, chlorophyll a (Chl-a), total phosphorus (TP), total nitrogen(TN) and silica concentration were in the range of 0.9-3.5 m, 0.1-8.5 NTU, 0.3-32.4 mgChl $m^{-3}$, 5-46 mgP $m^{-3}$, 0.83-3.55 mgN $L^{-1}$ and 0.5-9.6 mgSi $L^{-1}$, respectively. Green algae and cyanobacteria dominated phytoplankton community in warm seasons, from July through October, 2000. In July a green alga (Scenedesmus sp.) was dominant with a maximum cell density of 10,480 cells mL. Cyanobacteria (Microcystics sp.) dominated in August and September with cell density of 3,492 and 295 cells mL ,respectively. Species diversity of phytoplankton was highest (2.22) in July. The trophic state of the reservoir can be classified as eutrophic on the basis of TP, Chl-a, and Secchi disc transparency. Because TP concentration was high in flood period, most of phosphorus loading was concentrated in rainy season. TP loading was calculated by multiplying TP and flow rate. The dam managing company measured inflow rate of the reservoir daily, while TP was measured by weekly surveys. TP of unmeasured days was estimated from the empirical relationship of TP and the flow rate of the main tributary; $TP=5.59Q^{0.45}\;(R^2=0.47)$. Annual TP loading was calculated to be 4.45 tP $yr^{-1}$, and the areal P loading was 0.77 gP $m^{-2}\;yr^{-1}$ which is similar to the critical P loading for eutrophication by Vollenweider's phosphorus model, 0.72 gP $m^{-2}\;yr^{-1}$.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.797-806
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• 2000

The objectives were to compare the biodegradable threshold concentrations of phenol with the different composition of the influent carbon source and examine the SMA (Specific Methanogenic Activity)and the possibility of simultaneous removal of high-strength organics and nitrogen compounds in UASB(Upflow Anaerobic Sludge Blanket) - PBR(Packed Bed Reactor) process. The results showed that UASB reactors were efficient to remove phenol and phenol + glucose from synthetic wastewater. At phenol conc, of 600 mg/L and SCOD conc. of 2100 mg/L in UASB reactor(with only phenol as substrate), the removal efficiencies of phenol and SCOD were over 99% and 93% respectively, under MLVSS of 20 g. The activity of microorganism was $0.112g\;phenol/g\;VSS{\cdot}d$, $0.351g\;SCOD/g\;VSS{\cdot}d$. The gas production rate was $0.115L/g\;VSS{\cdot}d$ and $CH_4$ content in gas was about 70%. At phenol conc. of 760 mg/L and SCOD conc. of 4300 mg/L in UASB reactor( with phenol + glucose as substrates), the removal efficiencies of phenol and of SCOD were over 99% and 90% respectively, under MLVSS of 20 g. The activity of microoganism was $0.135g\;phenol/g\;VSS{\cdot}d$, $0.696g\;SCOD/g\;VSS{\cdot}d$. The gas production rate was $0.257L/g\;VSS{\cdot}d$ and $CH_4$ content in gas was about 70%. Serum bottle test showed that the activity of granule was inhibited over 1600 mg/L phenol conc, and denitrification and methanogenesis simultaneously took place in UASB granules under co-substrates conditions. PBR reactor packed with cilium type media, was efficient in nitrification. In condition of $0.038kg\;NH_4-N/m^3-media{\cdot}d$. 10~12 mg/L phenol conc. and 200~500 mg/L SCOD conc., nitrification efficiency was over 90% and phenol removal efficiency was over 98%.

• Fire Science and Engineering
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• v.30 no.2
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• pp.7-18
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• 2016

This study evaluated the toxicity of the burning gas from the synthetic wood products used in housings or warehouses. The combustion products of five materials, viz. impregnated laminated board, MDF, Douglas fir plywood, core plywood, and Lauan retardant, were analyzed using SEM, FTIR and a Cone Calorimeter. For the Lauan retardant, 256,965 ppm of carbon dioxide ($CO_2$) and 1,475 ppm of sulfur dioxide ($SO_2$) were measured, which are 2.5 times and 3.6 times as high as their lethal concentrations of 100,000 ppm and 400 ppm, respectively. For the impregnated laminated board, 1,569 ppm of nitrogen dioxide ($NO_2$) was measured, which is 6 times as high as its lethal concentration of 250 ppm. For MDF, 795 ppm of ammonia ($NH_3$) was measured, which is higher than its lethal concentration of 750 ppm. As a result, most internal-finishes generated toxic combustion products at levels higher than their lethal concentrations, which underlines the importance of the selection and manufacturing of internal-finish materials.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.73-84
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• 1975

The present study was conducted to evaluate the effects of oil spill from the wastewater of Yeosu Refinery on water quality of hard clam culture beds in Taein-Ri, Kwang Yang Bay. Wastewater and oil spill may reach to the culture beds in 6-8 hours by tidal current movement. Water quality is nearly normal as unpolluted sea water except the concentration of n-hexane extractive chemicals which shows higher than unpolluted sea water in period of September to October in 1973. It may be caused by wastewater of Yeosu Refinery.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.896-901
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• 2000

The effect of gamma-irradiation on the microbiological and general quality changes of the Chungkukjang was studied. Chungkukjang was prepared, irradiated at 0, 5, 10 and 20 kGy, and then stored at $25^{\circ}C$ for six weeks. The results showed that the vegetative Bacillus cell was decreased by 5 log cycles with dose of 10 kGy with 1.78 kGy of $D_{10}$ value. Also, Bacillus was nearly eliminated by 20 kGy and that survived 10 kGy gamma irradiation was decreased significantly with the duration of storage period. The formation of $NH_{2}-nitrogen$ and $NH_{3}-nitrogen$, acidification and browning were repressed by gamma irradiation. Therefore, it was considered that the Chungkukjang treated with gamma irradiation maintained better quality than that of the control with storage.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.367-375
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• 2006

Sequencing Batch Reactor (SBR) is well adopted for community wastewater treatment for its simplicity, performance and various advantageous treatment options. SBR is now drawing attention for its process modification such as coupled with membrane bioreactor, reverse osmosis or applying different media to achieve high removal efficiency. This study focused on the improved efficiency of carbon, nitrogen and phosphorous removal by applying zeolite materials called bioceramics to the SBR. Two laboratory-scale SBR units were operated in the same operating conditions - one with bioceramics called Bioceramic SBR (BCSBR) and the other without bioceramics used as control. Routine monitoring of COD, TP, $NH_3-N$, $NO_3-N$ was performed throughout this study. COD removal was about 80% to 100% and phosphorous removal was about 60% in the process whereas $NH_3-N$ removal efficiency was found to be 99.9% in the BCSBR unit. Addition of bioceramics also improved sludge characteristics such as sludge dewaterability, specific gravity and particle size. BCSBR can withstand high ammonia shock loading leading to the better treatment capacity of high ammonia containing wastewater. The cause of improved removal efficiencies within the biological reactor could be attributed to the biochemosorption mechanisms of bioceramics. Absorption/adsorption or desorption capacity of bioceramics was tested through laboratory experiments.