• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.51-60
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• 2000

In order to understand the trend and assessment of water pollution, seasonal water quality was determined in the main river and the tributaries from midstream to downstream of the Kum River from March 1998 to June 1999. Among environmental factors, the variation of nitrogen, phosphorus and chlorophyll-a was distinctive on an aspect of increase and decrease relatively to others, and particularly the impact of inorganic N ${\cdot}$ P inflowing into the main river was observed to be more significant at the Kapchon, Mihochon and Soksongchon among the tributaries. Water quality was highly related to hydrologic factor, and it was more deteriorated when water discharge maintains for a long time below normal flow or relatively at low condition of minimum and drought flow. These phenomena were remarkablee from December to March of the next year. $NH_4$ and SRP were decreased dramatically flowing toward the lower part of the river and chl-a was increased exponentially. While, the variations of $NO_3$ and $BOD_5$ were regular from midstream to downstream and there was no significant difference between the stations. Limiting nutrient for Phytoplankton growth seemed to be P than N because the ratio of TN/TP or DIN/SRP was relatively high as 42 or 544 in the main river, respectively. The main river and tributaries were ranked to be third grade, based on the assessment of BOD as an indirect indicator of organics, but particularly Kapchon was ranked to be over fifth grade. In addition, the inflow of high N ${\cdot}$ P nutrients from tributaries including Kapchon and Mihochon seemed to be major factor of the development of water pollution of the Kum River. On the other hand, persistent bloom of phytoplankton in lower part of the river was observed. As a conclusion, management of water quality for main source of pollution is urgent.

• Journal of Energy Engineering
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• v.5 no.2
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• pp.160-169
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• 1996

Parametric studies are conducted for optimizing the integration design between gas turbine compressor and air separation unit (ASU) of integrated gasification combined cycle power plant. The present study adopts the ASU of double-distillation column process, from which integration conditions with compressor such as the heat exchanger condition between air and nitrogen, the amount and the pressure of extracted air are defined and mathematically formulated. The performance variations of the compressor integrated with ASU are analyzed by combining streamline curvature method and pressure loss models, and the predicted results are compared with the performance test results of actual compressors to verify the prediction accuracy. Using the present performance prediction method, the effects of pinch-point temperature difference (PTD) in the heat exchanger, the amount and the pressure of extracted air on compressor performances are quantitatively examined. As the extraction air amount or the PTD is increased, the pressure ratio and the power consumption of compressor are increased. The compressor efficiency deteriorates as the increase of the flow rate of air extracted at higher pressure level while improving at lower pressure air extraction. Furthermore, through the characteristic curve between generalized inlet condition and efficiency of compressor, optimal integration condition is presented to maximize the compressor efficiency.

• Journal of Animal Science and Technology
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• v.59 no.10
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• pp.23.1-23.11
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• 2017

Background: Although soybean meal (SBM) is excellent source of protein in diets for poultry, it is sometimes inaccessible, costly and fluctuates in supply. The SBM can partially be replaced by full-fat SBM, but the meals prepared from raw full-fat soybean contain antinutritional factors. To avoid the risk of antinutritional factors, heat treatment is always advisable, but either excessive or under heating the soybean could negatively affect the quality. However, the potential for further improvement of SBM by supplementing with microbial enzymes has been suggested by many researchers. The objective of this study was to evaluate the performance and ileal nutrient digestibility of birds fed on diets containing raw soybeans and supplemented with microbial protease. Methods: A $3{\times}2$ factorial, involving 3 levels of raw full-fat soybean (RFFS; 0, 45 or 75 g/kg of diet) and 2 levels of protease (0 or 15,000 PROT/kg) was used. The birds were raised in a climate-controlled room. A nitrogen-free diet was also offered to a reference group from day 19 to 24 to determine protein and amino acid flow at the terminal ileum and calculate the standardized ileal digestibility of nutrients. On days 10, 24 and 35, body weight and feed leftover were recorded to calculate the body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). On day 24, samples of ileal digesta were collected at least from two birds per replicate. Results: When RFFS was increased from 0 to 75 g/kg of diet, the content of trypsin inhibitors was increased from 1747 to 10,193 trypsin inhibitors unit (TIU)/g of diets, and feed consumption of birds was also reduced (P < 0.05). Increasing RFFS level reduced the BWG from hatch 0 to 10 d (P < 0.01) and hatch to 24 d (P < 0.05). The BWG of birds from hatch to 35 was not significantly (P = 0.07) affected. Feed intake was also reduced (P < 0.05) during 0 to 35 d. However, protease supplementation improved (P < 0.05) the BWG and FCR during 0 to 24 d. Rising levels of RFFS increased the weight of pancreas (P < 0.001) and small intestine (P < 0.001) at day 24. Except for methionine, apparent and the corresponding standardized ileal digestibility of CP and AA were reduced (P < 0.01) by increasing levels of RFFS in diets. Conclusion: This study showed that some commercial SBM could be replaced by RFFS in broiler diets, without markedly compromising productivity. The AID and SID of CP and lysine were slightly improved by dietary supplementation of microbial protease.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.2
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• pp.79-85
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• 2012

In this study, Application of sequencing batch reactor (SBR) process for RO retentate treatment was performed. Efficiency of treatment by load and temperature variation was tested. The SBR process was operated two types as HRT per one cycle was 8 and 12 hours, respectively. Methanol was injected for an effective denitrificaion owing to low C/N ratio of the RO retentate. TN removal efficiency of the SBR process was relatively stable at the change of flow-rate and temperature. The optimum time cycle of SBR process was 2 cycle/day for TN removal, and in the case of 3 cycle/day, the effluent TN concentration was found under the effluent quality standard. In the result of assessment, the application of SBR process for RO retentate treatment was effective and could be utilized to design for the wastewater treatment plant. The specific nitrification rate (SNR) and specific denitrification rate (SDNR) were $0.043{\sim}0.066kg\;NH_3-N/kg\;MLVSS{\cdot}day$ and $0.096{\sim}0.287kg\;NH_3^--N/kg\;MLVSS{\cdot}day$, respectively. The derived kinetic could be applied for design to the aerobic and anoxic tank in the RO retentate treatment.

• Membrane Journal
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• v.24 no.1
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• pp.63-68
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• 2014

Manufacturing facility for non-alcoholic drink, the parts of the food industry, disposes wastewater which includes high organic concentration and low nitrogen, phosphorus concentration. For this kind of wastewater, the treatment plant consists mainly of aerobic reactor and chemical coagulation process. And sand-filter or activated carbon process is normally installed further. However, aerobic reactor must have long HRT to treat high concentration of organic contaminant included in this wastewater, so the large site area is required. And settling tank which is normally applied for wastewater treatment facility has some problems such as water quality degradation caused by the sludge spill. To solve these problems, we applied MBR system for the wastewater. And the MBR pilot plant was installed nearby the wastewater treatment facility of W food factory and operated during long term to evaluate treatment efficiency. This plant was operated about 3 months and than the result was 97% of organic removal rate on conditions of flow rate $20m^3/day$, HRT 29 hr, recycle 4Q. However, contaminant removal ratio of bio-reactor decreased and TMP of membrane increased rapidly on more conditions.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.745-750
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• 2005

Naphtha cracking bottoms(NCB) oil was reformed by varying the heat treatment temperature, treatment time, and nitrogen flow rate in preparation of precursor pitch for isotropic pitch-based carbon fibers and activated carbon fibers. The reformed pitches were investigated in the yield, softening point, elementary analysis, and molecular weight distribution, and then the precursors reformed were melt spun to certify the optimum reforming conditions. The optimum precursor pitch was prepared when the NCB oil was reformed at $380^{\circ}C$, 3 h and 1.25 vvm $N_2$, and it's the softening point was around $240^{\circ}C$. The reforming resulted in product yield of 21 wt％. The C/H mole ratio of the precursor pitch increased from 1.07 to 1.34, the aromaticity increased from 0.85 to 0.88. The insolubles in benzene and quinoline were 30.0 wt％ and 1.5 wt％, respectively. The spinning temperature was about $50^{\circ}C$ higher than the softening point. The molecular weights of the precursor components were distributed from 250 to 1250, and 80％ of them were in the range of 250 to 700.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.40-49
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• 2019

Coarse woody debris (CWD), which is a component of the forest ecosystem, plays a major role in forest energy flow and nutrient cycling. In particular, CWD isolates carbon for a long time and is important in terms of slowing the rate of carbon released from the forest to the atmosphere. Therefore, this study measured the physiochemical characteristics and respiration rate ($R_{CWD}$) of CWD for Larix kaempferi and Pinus rigida in temperate forests in central Korea. In summer 2018, CWD samples from decay class (DC) I to IV were collected in the 14 forest stands. $R_{CWD}$ and physiochemical characteristics were measured using a closed chamber with a portable carbon dioxide sensor in the laboratory. In both species, as CWD decomposition progressed, the density ($D_{CWD}$) of the CWD decreased while the water content ($WC_{CWD}$) increased. Furthermore, the carbon concentrations did not significantly differ by DC, whereas the nitrogen concentration significantly increased and the C/N ratio decreased. The respiration rate of L. kaempferi CWD increased significantly up to DC IV, but for P. rigida it increased to DC II and then unchanged for DC II-IV. Accordingly, except for carbon concentration, all the measured characteristics showed a significant correlation with $R_{CWD}$. Multiple linear regression showed that $WC_{CWD}$ was the most influential factor on $R_{CWD}$. $WC_{CWD}$ affects $R_{CWD}$ by increasing microbial activity and is closely related to complex environmental factors such as temperature and light conditions. Therefore, it is necessary to study their correlation and estimate the time-series pattern of CWD moisture.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.131-138
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• 2011

This study was carried out to investigate on the composting characteristics variation accoding to air supply capacity in Pig manure. The composting of pig manure is economical and efficiently process. The fermented compost was added in pig manure mixed with sawdust was composting reators. Air supply capacity levels of fermented compost on the pig manure mixed with sawdust were regulated at 50, 100, 150 and 200$\ell/m^3$/min. respectively. The obtained results can be followed as bellow; The temperature variations of experimental composting piles during composting for the different of T-1 reach $40^{\circ}C$ in 2 days, T-2, T-3 and T-4 reach $60^{\circ}C$ in 2 days and T-3, T-4 maintained until 8 days. The decreases in water contents per each square meter for the different of T-1 (50 l/$m^3$/min), T-2(100 l/$m^3$/min), T-3(150 l/$m^3$/min) and T-4(200 l/$m^3$/min.), The decreases ratio in water contents was T-1, T-2, T-3 and T-4 were 15.4%, 28.8%, 33.4% and 35.2%. The decreases ratio in weight was T-1, T-2, T-3 and T-4 were 7.6%, 15.6%, 16.8% and 16.9% respectively. The variations of oxygen concentration from composting period in case of oxygen discharge concentration T-1, T-2, T-3 and T-4 were 9 ppm. respectively. Fertilizer components after composting were examined. Nitrogen contents of the T-1, T-2, T-3 and T-4 were 0.45%, 0.44%, 0.42% and 0.44%, and P2O5 contents were T-1, T-2, T-3 and T-4 were 0.37%, 0.41%, 0.42% and 0.44% respectively. Therefore, the compost curing air supply of air volumes at least 150$\ell$/min/min. or more to supply the aerobic composting pig manure normally are judged to be possible.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.493-501
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• 1993

As the dispersants and the dispersant/oil mixtures are degraded naturally by the microorganisms in the seawater, the consumption of dissolved oxygen may cause marine organisms to be damaged especially in the waters where the dissolved oxygen level is low due to the pollution and the restriction of seawater flow. The biodegradation experiment, the TOD analysis and the element analysis for three dispersants(SG, GL and WC) and a nonionic surfactant(OA-5) were conducted for the purposes of evaluating the biodegradability of dispersants and studying the effect of dispersants on dissolved oxygen in the seawater. The results of biodegradation experiment showed 1mg of dispersants to be equivalent to $0.403{\sim}0.595mg$ of $BOD_5$ and to $0.703{\sim}0.855mg$ of $BOD_{20}$, and 1mg of nonionic surfactant to be equivalent to 0.50mg of $BOD_5$ and to 0.97mg of $BOD_{20}$ in the natural seawater. The results of TOD analysis showed 1mg of dispersants to be $2.37{\sim}2.80mg$ of TOD and 1mg of nonionic surfactant to be 2.45mg of TOD. The results of element analysis showed carbon content and hydrogen content to be $67.6{\sim}76.5\%$ and $10.2{\sim}12.2\%$ for dispersants, and $65.3\%$ and $10.3\%$ for nonionic surfactant, respectively. No nitrogen element was detected in dispersants and a nonionic surfactant. The biodegradability of dispersants shown as the ratio of $BOD_5/TOD$ was found to be in the range of $17{\sim}21\%$, and that of nonionic surfactant was found to be about $20\%$. This means that dispersants and nonionic surfactant belong in the organic matter group of middle-biodegradabilily. The deoxygenation rates($K_1$) and ultimate oxygen demands($L_o$) obtained through the biodegration experiment and Thomas slope method were found to be $0.121{\sim}0.171/day$ and $3.155{\sim}3.810mg/l$ for 4mg/l of dispersants and to be 0.181/day and 1.911mg/l for 2mg/l of nonionic surfactant in the seawater, respectively.