• Journal of Energy Engineering
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• v.10 no.3
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• pp.188-194
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• 2001

The process simulations are made on the IGCC power plant using heavy residue oil from refinery process. In order to model combined power block of IGCC, the present study employs the gas turbine of MS7001FA model integrated with ASU (Air Separation Unit), and considers the air extraction from gas turbine and the combustor dilution by returned nitrogen from ASU. The exhaust gas energy of gas turbine is recovered through the bottoming cycle with triple pressure HRSG (Heat Recovery Steam Generator). Clean syngas fuel of the gas turbine is assumed to be produced through Shell gasification of Visbreaker residue oil and Sulfinol-SCOT-Claus gas cleanup processes. The process optimization results show that the best efficiency of IGCC plant is achieved at 20% air extraction condition in the case without nitrogen dilution of gas turbine combustor find at the 40% with nitrogen dilution. Nitrogen dilution of combustor has very favorable and remarkable effect in reducing NOx emission level, while shifting the operation point of gas turbine to near surge point.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.432-439
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• 2021

Microbial community plays important roles in the culture environment of mud crab Scylla serrata. One of the environmental management efforts for the cultivation of S.serrata is by stabilizing microorganisms involved in nitrogen cycle process. The availability of dissolved inorganic nitrogen in its culture environment under a recirculating system closely relates to the nitrogen cycle, which involves both anaerobic and aerobic bacterial activities. Anaerobically, there are two major nitrogen compound degradation processes, i.e., denitrification and dissimilatory nitrate reduction to ammonium (DNRA). This study aimed to identify denitrifying and DNRA bacteria isolated from the recirculating cultivation of S. serrata. The water samples were collected from anaerobic filters called close filter system, which is anaerobically conditioned with the addition of varying physical filter materials in the recirculating mud crab cultures. The results showed that three denitrifying bacterial isolates and seven DNRA bacterial isolates were successfully identified. The phylogenetic analysis based on 16S rRNA gene of the denitrifying bacteria revealed that HIB_7a had the closest similarity to Stenotrophomonas daejeonensis strain MJ03. Meanwhile, DNRA bacterial isolate of HIB_92 showed a 100% similarity to Bacillus sonorensis strain N3, Bacillus vallismortis strain VITS-17, Bacillus tequlensis strain TY5, Geobacillus sp. strain DB24, Bacillus subtilis strain A1, and Bacillus mojavensis strain SSRAI21. This study provides basic information denitrifying and DNRA bacterial isolates identity which might have the potential to be applied as probiotics in aquaculture systems in order to maintain optimal environmental conditions.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.76-87
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• 2005

Various disorders cause hyperammonemia during childhood. Amongthem are those caused by inherited defects in urea synthesis and related metabolic pathways. These disorders can be grouped into two types: disorders of the enzymes that comprise the urea cycle, and disorders of the transporters or metabolites of theamino acids related to the urea cycle. Principal clinical features of these disorders are caused by elevated levels of blood ammonium. Additional disease-specific symptoms are related to the particular metabolic defect. These specific clinical manifestations are often due to an excess or lack of specific amino acids. Treatment of urea cycle disorders and related metabolic diseases consists of nutritional restriction of proteins, administration of specific amino acids, and use of alternative pathways for discarding excess nitrogen. Although combinations of these treatments are extensively employed, the prognosis of severe cases remains unsatisfactory. Liver transplantation is one alternative for which a better prognosis is reported.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.273-279
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• 2011

Concerns over the environment have spawned a number of research studies in the construction industry, as the construction of built environments and large infrastructures involves diverse environmental impacts and loads of hazardous emissions. Many researchers have attempted to quantify these environmental loads, including greenhouse gases, carbon dioxide, nitrogen dioxide, and sulfur dioxide, to name a few. However, little research has been conducted regarding integrating the life-cycle assessment (LCA) of environmental loads with the current life-cycle cost analysis (LCCA) approach. This study aims to estimate the environmental loads as a monetary value using the European Climate Exchange (ECX) rate and, then, to integrate those impacts with the pure construction cost. Toward this end, this study suggests an integrated approach that takes into account the environmental effect on the evaluation of the life-cycle cost (LCC). The bill of quantity (BOQ) data of a real highway project are collected and analyzed for this purpose. As a result, considering the environmental loads in the pavement process, the total LCC increased 16% from the traditional LCC cost. This study suggests an integrated approach that will account the environmental effect on the LCC. Additionally, this study is expected to contribute to better decision-making, from the perspective of more sustainable development, for government as well as for contractors.

• Journal of Ocean Engineering and Technology
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• v.20 no.1 s.68
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• pp.55-62
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• 2006

Recently, pollution by development in coastal areas is going from bad to worse. The Korean government is attempting to make policies that prevent water pollution, but it is still difficult to say whether such measures are lowering pollution to an acceptable level. More specifically, the general investigation that has been done in KOREA does not accurately reflect the actual conditions of pollution in coastal areas. An investigation that quantitatively assesses water quality management using rational prediction technology must be attempted, and the ecosystem model, which incorporates both the 3-dimensional hydrodynamic and material cycle models, is the only one with a broad enough scope to obtain accurate results. The hydrodynamic model, which includes advection and diffusion, accounts for the ever-changing flow and (quality) of water in coastal areas, while the material cycle model accounts for pollutants and components of decomposition as sources of the carbon, phosphorus, and nitrogen cycles. In this paper, we simulated the rates of dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen(T-N) and total-phosphorous(T-P) in Korea's Ulsan Area. Using the ecosystem model, we did simulations using a specific set of parameters and did comparative analysis to determine those most appropriate for the actual environmental characteristics of Ulsan Area. The simulation was successful, making it now possible to predict the likelihood of coastal construction projects causing ecological damage, such as eutrophication and red tide. Our model can also be used in the environmental impact assessment (EIA) of future development projects in the ocean.

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.23-36
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• 2009

In the present work, the metabolic network of primary metabolism of the slow-growing myxobacterium Sorangium cellulosum was reconstructed from the annotated genome sequence of the type strain So ce56. During growth on glucose as the carbon source and asparagine as the nitrogen source, So ce56 showed a very low growth rate of $0.23\;d^{-1}$, equivalent to a doubling time of 3 days. Based on a complete stoichiometric and isotopomer model of the central metabolism, $^{13}C$ metabolic flux analysis was carried out for growth with glucose as carbon and asparagine as nitrogen sources. Normalized to the uptake flux for glucose (100%), cells recruited glycolysis (51%) and the pentose phosphate pathway (48%) as major catabolic pathways. The Entner-Doudoroff pathway and glyoxylate shunt were not active. A high flux through the TCA cycle (118%) enabled a strong formation of ATP, but cells revealed a rather low yield for biomass. Inspection of fluxes linked to energy metabolism revealed that S. cellulosum utilized only 10% of the ATP formed for growth, whereas 90% is required for maintenance. This explains the apparent discrepancy between the relatively low biomass yield and the high flux through the energy-delivering TCA cycle. The total flux of NADPH supply (216%) was higher than the demand for anabolism (156%), indicating additional reactions for balancing of NADPH. The cells further exhibited a highly active metabolic cycle, interconverting $C_3$ and $C_4$ metabolites of glycolysis and the TCA cycle. The present work provides the first insight into fluxes of the primary metabolism of myxobacteria, especially for future investigation on the supply of cofactors, building blocks, and energy in myxobacteria, producing natural compounds of biotechnological interest.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.291-301
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• 2002

In this study, nutrients treatment by sequencing batch reactors(SBR) was performed. Nitrogen and phosphorus removal efficiencies were evaluated by changing SRT and mixing/aeration ratio. Not only nitrogen but also phosphorus removal patterns were investigated through track studies on 1 cycle. As SRT was fixed and mixing/aeration ratio was changed, maximum nitrogen removal efficiency was 87.6% at mixing/aeration ratio 0.67. Phosphorus removal efficiencies were more than 85.5% except no mixing condition. As mixing/aeration ratio was fixed and SRT was changed, nitrogen removal efficiencies were 70.5~79.8%, which represented slight changes, while phosphorus removal efficiencies were 49.0~97.3%, which represented sharply decreasing tendency at less than 20 day. Both phosphorus release rate k and maximum phosphorus release rate $P_{max}/M$ were are decreased as SRT was decreased, but they were not affected by mixing/aeration ratio. It was found that there is a linear relationship between ortho-phosphate uptake and maximum ortho-phosphate release.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.815-826
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• 2013

Using a developed mathematical model and calibrated kinetic constants, numerical experiments for a aerobic digestion of wastewater sludge by SBR aerobic digestion process combined with ultrasonication (USSBR) were performed in this study. It simulated well the phenomena of the decomposition of particulate organics and the release of organic nitrogen and transformation. To achieve 40 % of particulate organics removal, USSBR process requires only 6 days of SRT and 14 W/L of ultrasonic power whereas SBR aerobic digestion process requires 12 days of SRT. Based on the model simulation results, an empirical equation was presented here. This equation will be used to predict digestion efficiency for the given variables of SRT and ultrasonic power dose. USSBR aerobic digestion process can reduce the nitrogen concentration. The optimal operation strategy for the simultaneous removal of solids and soluble nitrogen in this process is estimated to 7 days of SRT with 14 W/L of ultrasonic power dose while anoxic period was 6 hours out of 24 hours of cycle time. In this condition, 40 % of particulate organics as well as 36 % of total nitrogen will be removed and the soluble nitrogen concentration of the centrate will be lower less then 40 mg/L.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.sup1
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• pp.11-11
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• 2009

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.12-17
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• 2017

Design of Reverse Stirling Cycle based refrigerator can be predicted by Schmidt theory as a useful tool and by experiment it is found that for practical purposes the power and efficiency predicted by this analysis are about 35% of the actual values. Therefore, appropriate provision is to be made for getting the realistic result with the minimum deviation. The present paper first investigates the suitability of application of Schmidt design analysis for standard ZIF-1002 and PLN-106 Single cylinder Cryogenerator model. As the result is found to be optimistic, the same design procedure is applied for the design of a separate Cryogenerator for generating a cooling effect which is sufficient to produce 7 kg per hour liquid nitrogen using an indigenous condenser of 80% effectiveness. The paper describes all the details of the design methodologies and relevant results are found to be satisfactory.