• Advances in Energy Research
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• v.5 no.2
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• pp.91-105
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• 2017

Thermal hydraulic (TH) analysis of nuclear power reactors is utmost important. In this way, the numerical codes that preparing TH data in reactor core are essential. In this paper, a subchannel analysis of a Russian pressurized water reactor (WWER1000) core with enhanced numerical code is carried out. For this, in fluid domain, the mass, axial and lateral momentum and energy conservation equations for desired control volume are solved, numerically. In the solid domain, the cylindrical heat transfer equation for calculation of radial temperature profile in fuel, gap and clad with finite difference and finite element solvers are considered. The dependence of material properties to fuel burnup with Calza-Bini fuel-gap model is implemented. This model is coupled with Isotope Generation and Depletion Code (ORIGEN2.1). The possibility of central hole consideration in fuel pellet is another advantage of this work. In addition, subchannel to subchannel and subchannel to rod connection data in hexagonal fuel assembly geometry could be prepared, automatically. For a demonstration of code capability, the steady state TH analysis of a the WWER1000 core is compromised with Thermal-hydraulic analysis code (COBRA-EN). By thermal hydraulic parameters averaging Fuel Assembly-to-Fuel Assembly method, the one sixth (symmetry) of the Boushehr Nuclear Power Plant (BNPP) core with regular subchannels are modeled. Comparison between the results of the work and COBRA-EN demonstrates some advantages of the presented code. Using the code the thermal modeling of the fuel rods with considering the fission gas generation would be possible. In addition, this code is compatible with neutronic codes for coupling. This method is faster and more accurate for symmetrical simulation of the core with acceptable results.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1193-1201
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• 2012

The analysis and quantification of ammonia-oxidizing bacteria (AOB) is crucial, as they initiate the biological removal of ammonia-nitrogen from sewage. Previous methods for analyzing the microbial community structure, which involve the plating of samples or culture media over agar plates, have been inadequate because many microorganisms found in a sewage plant are unculturable. In this study, to exclusively detect AOB, the analysis was carried out via denaturing gradient gel electrophoresis using a primer specific to the amoA gene, which is one of the functional genes known as ammonia monooxygenase. An AOB consortium (S1 sample) that could oxidize an unprecedented 100% of ammonia in 24 h was obtained from sewage sludge. In addition, real-time PCR was used to quantify the AOB. Results of the microbial community analysis in terms of carbon utilization ability of samples showed that the aeration tank water sample (S2), influent water sample (S3), and effluent water sample (S4) used all the 31 substrates considered, whereas the AOB consortium (S1) used only Tween 80, D-galacturonic acid, itaconic acid, D-malic acid, and $_L$-serine after 192 h. The largest concentration of AOB was detected in S1 ($7.6{\times}10^6copies/{\mu}l$), followed by S2 ($3.2{\times}10^6copies/{\mu}l$), S4 ($2.8{\times}10^6copies/{\mu}l$), and S3 ($2.4{\times}10^6copies/{\mu}l$).

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.384-388
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• 2008

Hydrogen production via high high-temperature steam electrolysis consumes less electrical energy than compared to conventional low low-temperature water electrolysis, mainly due to the improved thermodynamics and kinetics at elevated temperaturetemperatures. The elementalElemental powders of Cu, Ni, and YSZ are were used to synthesize high high-temperature electrolysis cathodecathodes, of Ni/YSZ and Cu/YSZ composites, by mechanical alloying. The metallic particles of the composites were uniformly covered with finer YSZ particles. Sub-micron sized pores are were homogeneously dispersed in the Ni/YSZ and Cu/YSZ composites. In this study, The cathode materials were synthesized and their Characterizations properties were evaluated in this study: It was found that the better electric conductivity of the Cu/YSZ composite was measured improved compared tothan that of the Ni/YSZ composite. Slight A slight increase in the resistance can be produced for in a Cu/YSZ cathode by oxidation, but it this is compensated offset for by a favorable thermal expansion coefficient. Therefore, Cu/YSZ cermet can be adequately used as a suitable cathode material of in high high-temperature electrolysis.

• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.51-56
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• 2014

In this paper, OTEC(Ocean Thermal Energy Conversion) system with vapor-vapor ejector is newly proposed. And 6 wet refrigerants are applied into the proposed OTEC system for performance comparison. The results of comparison performance are as follows. In the view of system efficiency, R32/R744(90:10) has the highest efficiency among the 6 refrigerants. In case of evaporation capacity, pump work and mass flow rate of working fluid, R744, R717 and R717 is lowest value, respectively. As this results, the vapor-vapor ejector is able to increase the efficiency of system. And It is necessary to select the optimized working fluid considering environmental and economic factors.

• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.45-50
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• 2014

In this paper, the Ocean Thermal Energy Conversion(OTEC) with vapor-vapor ejector is proposed newly. At this OTEC system, a vapor-vapor ejector is installed at inlet of condenser. The vapor-vapor ejector plays a very important role in increasing of the production work of low-stage turbine throughout the decrement of outlet pressure of ejector. The performance analysis is conducted for optimizing the system with HYSYS program. The procedure of performance analysis consists of outlet pressure of high turbine, the mass ratio of working fluid at separator, total working fluid rate, and nozzle diameters of vapor-vapor ejector. The main results is summarized as follows. The nozzle diameter is most important thing in this study. When each nozzle diameter of vapor-vapor ejector is 10 mm, the efficiency of OTEC system with vapor-vapor ejector shows the highest value. So it is necessary to set the optimized nozzle diameters of vapor-vapor ejector for achieving the high efficiency OTEC power system.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.41-48
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• 2014

Leak of liquid has been categorized conventionally into instantaneous release and continuous release. In this study, the spread of cryogenic liquid due to limited period of release is investigated for the first time to establish a new classification method with recognizing the irrationality of the conventional one. Such physical phenomena are governed by simultaneous equations concerning volume, radius and height of pool of the cryogenic liquid, and major parameters are evaporation rate per unit area, time of release, and spill quantity. The simultaneous governing equations is decoupled to get efficiently perturbation solutions. As the results, for the same spill quantity, in view of release model, combined release model that consists of continuous and consecutive instantaneous model is necessary with small time of release, while continuous model is solely required with large time of release. Also, the combined model is necessary for small spill quantity with the same time of release. These two regimes of release are clearly distinguished using the perturbation solution to provide a clear basis for the new classification of release models.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.1-7
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• 2015

The environmental regulations for CO2 emissions from the ship have been established recently, and fuel oil price has been increased continuously. In order to overcome these circumstances, Energy Saving Devices (ESDs) have been developed continuously to reduce the fuel oil consumption and improve the propulsive efficiency. This paper describes the trial performance of PBCF (Propeller Boss Cap Fins), SCHNEEKLUTH duct, Asymmetric rudder bulb and Mewis duct applied to handy-size bulk carriers. As a result, SCHNEEKLUTH duct is more effective than other energy saving devices at the reducing the fuel oil consumption and the improvement of the propulsive efficiency. In addition, it is confirmed that SCHNEEKLUTH duct is really effective in the vibration of the deck house. And the fuel oil consumption can also be reduced through main engine de-rating.

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.43-49
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• 2003

Resistant cell lines to azetidine-2-carboxylic acid (AZCA) were selected through rice embryo culture after mutagenic treatment of callus irradiated with 30,50,70,90 and 120 Gy. The optimum AZCA concentration for the selection of resistant cell lines was 3 or 4 mM AZCA considering $LD_{50}$ and the fresh weight of callus. Survival rate of the AZCA resistant callus showed remarkable increase in the callus irradiated with 50 and 70 Gy. Regeneration rate of the AZCA resistant callus was much lower on the whole. Ninety and 120 Gy increased the regeneration rate for calli selected from 3 and 4 mM AZCA, respectively. Based on fresh weight, survival rate and regeneration for selection of the AZCA resistant cell line, 50-90 Gy was considered as the optimum range of gamma irradiation. Irradiated calli selected from AZCA were more tolerant to NaCl than those from non-irradiated calli. It suggests that elevated resistance to osmotic stress resulted from mutagenic treatment. The level of free proline content in the AZCA resistant cell line was increased up to 3.5 times compared with that in the control. Proline content in the regenerant derived from the AZCA resistant cell line also increased to 1.7 times that from the control plants regenerated from callus grown in AZCA free medium. Selection of proline overproducing cell lines by in vitro mutagenesis was successful and seems to be useful for improvement of stress tolerance in this crop.

• Research in Plant Disease
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• v.21 no.3
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• pp.193-200
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• 2015

Gray mold caused by Botrytis cinerea is one of the most important postharvest fungal pathogens of cut flowers. Here, gamma irradiation, an alternative for phytosanitary purposes, and sodium dichloroisocyanurate (NaDCC) were used to control B. cinerea in a cut chrysanthemum (Chrysanthemum morifolium Ramat.) cultivar, 'Baekma', one of the cultivars susceptible to B. cinerea. Spore germination and mycelium growth of B. cinerea were inhibited by gamma irradiation in an inversely dose-dependent manner. A dose of 4 kGy completely inhibited the mycelium growth of B. cinerea. A significant change in flower quality (physical properties) on chrysanthemum was shown from gamma irradiation at over 0.2 kGy (p<0.05). Therefore, in this study, the integration of gamma ray (below 0.2 kGy) and NaDCC, an eco-friendly form of chlorine, was investigated to control the disease with low dose of gamma irradiation dose. Interestingly, the gamma irradiated flowers showed more disease severity than the non-irradiated flowers. The combined treatment of gamma irradiation and NaDCC does not affect the severity of the fungal disease, whereas only 70 ppm of NaDCC treatment showed a significantly reduced severity. These results suggest that only chlorination treatment can be applied to control B. cinerea in cut chrysanthemum flowers.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.130-139
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• 2015

Korea country was set up over 30% greenhouse gas reduction target in comparision with BAU(Business as usal) at the national level, depending on climate change, which have been promoted as several technical and policy planning in order to reduce national greenhouse gas reduction. In this study, we derived the policies and technologies of power plant sector that is a high rate of reduction and public interest, we established a model for a common evaluation indicators and each of the evaluation factors between policy and technology priorities based on appropriate subject experts using analytic hierarchy process(AHP). Further we suggest insight to electricity company to establish the investment strategies of the technology and the associated policy by applying a weight evaluation index presenting a comprehensive priority.