• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.2
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• pp.10-16
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• 2019

In this study, the present regulation of heat metering for the ground source heat pump was investigated. The ground source heat pump has been adopting the heat metering system used in the district heating system for estimating the heating and cooling energy production amount. The accuracy of the present heat metering systems for a water to water ground source heat pump is low, because the system for district heating has a relatively high temperature range comparing with the ground source heat pump operating conditions. Even though the heat amount for the building side should be measured, the heat absorption and extraction amount from or to the ground was measured for the water to air ground source heat pump due to the difficulty of estimating the air side heating and cooling capacity in the present regulation. It is highly recommended to validate the heat metering system to have reliability for the ground source heat pump and develop the system to be applicable water to air ground source heat pump.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.39-49
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• 2021

The behaviors of various desorption agents were investigated during the desorption of cesium (Cs) from samples of clay minerals and actual soil. Results showed that polymeric cation exchange agents (polyethyleneimine (PEI)) efficiently desorbed Cs from expandable montmorillonite, whereas acidic desorption solutions containing HCl or PEI removed considerable Cs from hydrobiotite. However, most desorption agents could desorb only 54% of Cs from illite because of Cs's specific adsorption to selective adsorption sites. Cs desorption from an actual soil sample containing Cs-selective clay mineral illite (< 200 ㎛) and extracted from near South Korea's Kori Nuclear Power Plant was also investigated. Considerable adsorbed 137Cs was expected to be located at Cs-selective sites when the 137Cs loading was much lower than the sample's cation exchange capacity. At this low 137Cs loading, the total Cs amount desorbed by repeated washing varied by desorption agent in the order HCl > PEI > NH4+, and the highest Cs desorption amount achieved using HCl was 83%. Unlike other desorption agents with only cation exchange capabilities, HCl can attack minerals and induce dissolution of metallic elements. HCl's ability to both alter minerals and induce H+/Cs+ ion exchange is expected to promote Cs desorption from actual soil samples.

• Molecules and Cells
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• v.45 no.5
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• pp.294-305
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• 2022

E3 ligase BRUTUS (BTS), a putative iron sensor, is expressed in both root and shoot tissues in seedlings of Arabidopsis thaliana. The role of BTS in root tissues has been well established. However, its role in shoot tissues has been scarcely studied. Comparative transcriptome analysis with shoot and root tissues revealed that BTS is involved in regulating energy metabolism by modulating expression of mitochondrial and chloroplast genes in shoot tissues. Moreover, in shoot tissues of bts-1 plants, levels of ADP and ATP and the ratio of ADP/ATP were greatly increased with a concomitant decrease in levels of soluble sugar and starch. The decreased starch level in bts-1 shoot tissues was restored to the level of shoot tissues of wild-type plants upon vanadate treatment. Through this study, we expand the role of BTS to regulation of energy metabolism in the shoot in addition to its role of iron deficiency response in roots.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.265-276
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• 1994

Several improvements to the RELAP5/MOD3 reflood model hate been made. These improvement were made to correct deficiencies in the reflood model identified by the assessment of the RELAP5/MOD3 code against FLECHT-SEASET experiments. The improvements consist of modification of reflood wall heat transfer package and adjusting the droplet size in dispersed flow regime. The time smoothing of wall vaporization and level tracking of transition flow are also added to eliminate the pressure spikes and level oscillation during reflood process. Assessment of the improved model against FLECHT-SEASET experimental data and application of LBLOCA analysis for plant shows that the deficiencies have been corrected.

• Corrosion Science and Technology
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• v.4 no.4
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• pp.140-146
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• 2005

Fossil fired power plant produces the electric energy by using a thermal energy by the combustion of fossil fuels as like oil, gas and coal. The exhausted flue gas by the combustion of oil etc. contains usually many contaminated species, and especially sulfur-content has been controlled strictly and then FGD (Flue Gas Desulfurization) facility should be installed in every fossil fired power plant. To minimize the content of contaminations in final exhaust gas, high corrosive environment including sulfuric acid (it was formed during the process which $SO_2$ gas combined with $Mg(OH)_2$ solution) can be formed in cooling zone of FGD facility and severe corrosion damage is reported in this zone. These conditions are formed when duct materials are immersed in fluid that flows on the duct floors or when exhausted gas is condensed into thin layered medium and contacts with materials of the duct walls and roofs. These environments make troublesome corrosion and air pollution problems that are occurred from the leakage of those ducts. The frequent shut down and repairing works of the FGD systems also demand costs and low efficiencies of those facilities. In general, high corrosion resistant materials have been used to solve this problem. However, corrosion problems have severely occurred in a cooling zone even though high corrosion resistant materials were used. In this work, a new technology has been proposed to solve the corrosion problem in the cooling zone of FGD facility. This electrochemical protection system contains cathodic protection method and protection by coating film, and remote monitoring-control system.

• Journal of Hydrogen and New Energy
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• v.31 no.1
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• pp.82-88
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• 2020

Recently, a fuel reforming plant for supplying high purity hydrogen has been studied to increase the operation time of underwater weapon systems. Since steam reforming is an endothermic reaction, it is necessary to continuously supply heat to the reactor. A fuel reforming plant needs a methanol-O₂ catalytic burner to obtain heat and supply heat to the reformer. In this study, two types of designs of a catalytic burner are presented and the results are analyzed through the experiments. The design of the catalytic burner is divided into that the O₂ supply direction is perpendicular to the methanol flow direction (Design 1) and the same as the methanol flow direction (Design 2). In case of Design 1, backfire and flame combustion occurred in the mixing space in front of the catalyst, and in the absence of the mixing space, combustion reaction occurred only in a part of the catalyst. For above reasons, Design 1 could not increase the exhaust gas temperature to 750℃. In Design 2, no flashback and flame combustion were observed, the exhaust gas could be maintained up to 750℃. However, the O₂ distributor was exposed to high temperatures, resulting in thermal damage.

• International Journal of Fluid Machinery and Systems
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• v.10 no.2
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• pp.146-153
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• 2017

Sediment flow through hydropower components causes hydro-abrasive erosion resulting in loss of efficiency, interruptions in power production and downtime for repair/maintenance. Online instruments are required to measure/capture the variations in sediment parameters along with collecting samples manually to analyse in laboratory for verification. In this paper, various sediment parameters viz. size, concentration (TSS), shape and mineral composition relevant to hydro-abrasive erosion were measured and discussed with respect to a hydropower plant in Himalayan region, India. A multi-frequency acoustic instrument was installed at a desilting chamber to continuously monitor particle size distribution (PSD) and TSS entering the turbine during 27 May to 6 August 2015. The sediment parameters viz. TSS, size distribution, mineral composition and shape entering the turbine were also measured and analysed, using manual samples collected twice daily from hydropower plant, in laboratory with instruments based on laser diffraction, dynamic digital image processing, gravimetric method, conductivity, scanning electron microscope, X-ray diffraction and turbidity. The acoustic instrument was able to capture the variation in TSS; however, significant deviations were found between measured mean sediment sizes compared to values found in the laboratory. A good relation was found for turbidity ($R^2=0.86$) and laser diffraction ($R^2=0.93$) with TSS, which indicated that turbidimeter and laser diffraction instrument can be used for continuous monitoring of TSS at the plant. Total sediment load passed through penstock during study period was estimated to be 15,500 ton. This study shall be useful for researchers and hydropower managers in measuring/monitoring sediment for hydro-abrasive erosion study in hydropower plants.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.106-112
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• 2017

The present study describes flow induced noise generated from a ball valve used for a gas pipeline. Noise generation from a ball valve mainly induces by interference between unstable(or fluctuating) leakage flow and pipe wall when the ball valve is working closed or opened. To measure the positions of the noise source and the amplitude of noise with respect to measuring frequencies, a commercial acoustic camera is introduced. Noise characteristics generated by the ball valve have been performed by four valve opening rates: 30, 50, 70 and 100 percents. It is noted that 100 percent opening rate means that the valve is fully opened. Throughout the experimental measurements using the acoustic camera, the location of the noise source and the noise amplitude with respect to the frequencies for the test ball valve are clearly evaluated. It is found that the dominant frequencies come from the fluctuating flow at the downstream of the ball valve for four opening rates are observed between 3,000Hz and 3,200Hz. Maximum noise amplitude comes from the ball valve reaches 75dB at the valve opening rate of 50 percent.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.55.2-55.2
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• 2011

The final site of offshore wind power plant should be decided by comprehensive examination of various conditions such as wind resource, sea depth, geology, grid connection, social circumstance and environmental issue. Wind condition is typically regarded as the most important factor because wind energy increases in proportion to wind velocity and it directly relates to the amount of power output, efficiency of power plant and profitability. Advanced countries in the offshore wind power sector such as Denmark, UK and Germany, they are analyzing wind resource accurately by installing the meteorological mast in the ocean in order to get the optimal type of wind turbine and maximum generation efficiency. Also, it is made much of designing offshore power plant on the basis of actual measurement by met-mast and those wind farms have a chance to get the loan with reduced interest rate in project financing. In Korea, the HEMOSU-1 is installed in the ocean around Wido island to analyze wind resource of test bed of 100MW offshore wind power on october last year. This paper deals with the design and construction procedure of the first met-mast in Korea and also shows the site characteristics of test bed. Therefore, this paper will give useful information to local governments and private business sector who are trying to construct offshore wind farm and it can also be a good reference for the following projects of meteorological mast in near future.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.428-439
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• 2020

Erwinia pyrifoliae is a Gram-negative bacterial plant pathogen that causes black shoot blight in apple and pear. Although earlier studies reported the genome comparison of Erwinia species, E. pyrifoliae strains for such analysis were isolated in 1996. In 2014, the strain E. pyrifoliae EpK1/15 was newly isolated in the apple tree showing black shoot blight in South Korea. This study aimed to better understand the similarities and differences caused by natural variations at the genomic level between newly isolated E. pyrifoliae EpK1/15 and the strain Ep1/96, which were isolated almost 20 years apart. Several comparative genomic analyses were conducted, and Clusters of Orthologous Groups of proteins (COG) database was used to classify functional annotation for each strain. E. pyrifoliae EpK1/15 had similarities with the Ep1/96 strain in stress-related genes, Tn3 transposase of insertion sequences, type III secretion systems, and small RNAs. The most remarkable difference to emerge from this comparison was that although the draft genome of E. pyrifoliae EpK1/15 was almost conserved, Epk1/15 strain had at least three sorts of structural variations in functional annotation according to COG database; chromosome inversion, translocation, and duplication. These results indicate that E. pyrifoliae species has gone natural variations within almost 20 years at the genomic level, and we can trace their similarities and differences with comparative genomic analysis.