• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.

• Fire Science and Engineering
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• v.23 no.6
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• pp.10-15
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• 2009

Flame height calculation in a forest fire is a crucial part of predicting horizontal or vertical flame spread flared by radiation heat transfer. Flame height, which is one of the flame characteristics, can be estimated by the average height of luminous flame. This research relied on flame height observation test on P. densiflora surface fuel bed, which are surface combustibles in a forest, and calorimeter to measure Heat Release Rate, thus produced $H_f=0.027(\dot{Q'})^{2/3}$, flame height calculation equation for surface fuel. The research did not take into consideration such conditions as external velocity, slope and other variables that could affect flame height. According to comparison among experiment results, calculation results of the above formula and those of existing Heskestad formula (1998), it was found that standard error in fallen pine needles between experimental results and calculation results of the above formula amounts to 0.08, whereas standard error in same plant between experimental results and calculation results of existing Heskestad formula amounts to 0.23.

• Journal of Energy Engineering
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• v.8 no.4
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• pp.605-611
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• 1999

Conventional methods for assessing remaining life of critical high temperature components in fossil power plants rely on nondestructive inspection practices and accompanying life analysis based on fracture mechanics By using these conventional methods. It has been difficult to perform uninterrupted in-service inspection for life prediction. Thus, efforts have been made for developing on-line remaining life monitoring systems employing information on the shape of structures, operating variables and material properties. In thus study, a software for on-line life monitoring system which performs real-time life evaluation of a high temperature system headers was developed. The software is capable of evaluating creep and fatigue life usage from the real-time stress data calculated by using temperatures/stress transfer Green functions derived in advance for the specific headers. The major benefits of the developed software life in determining future operating schedule, inspection interval, and replacement plan by monitoring real-time life usage based on prior operating history.

• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.92-98
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• 2021

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS). Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach). METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding. On the 4 days after harvesting of preceding crop, spinach was sowed. The initial residual amounts of ethoprophos on soil (7.081-19.493 mg/kg) were decreased to 3.832-7.218 mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079 mg/kg after spinach cultivation. The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03% and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively. The residual amounts of uptake and translocation from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION: The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).

• Plant Journal
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• v.16 no.4
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• pp.40-44
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• 2020

In this study, after supplying a pulse wave to the 2 V Industrial Lead-Acid Battery electrode plate and repeating the charging and discharging, the discharging time per voltage was analyzed. According to the result of experiment, while the lead-acid Battery that a pulse wave is not supplied decreased about 18 % of discharging capacity than the beginning, the lead-acid Battery that a pulse wave is supplied decreased a little amount much lower than 18 %, of discharging capacity and recorded the 0.56 % decrease, at a minimum, from discharging capacity at the 20 kHz frequency. This means that the sulfate on electrode plate is detached and the positive and negative charge transfer is highly activated at the 20 kHz frequency

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.171-173
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• 2019

The genus Cohnella, which belongs to the family Paenibacillaceae, inhabits a wide range of environmental niches. Here, we report the complete genome sequence of Cohnella sp. HS21, which was isolated from the rhizospheric soil of Korean fir (Abies koreana) on the top of Halla Mountain in the Republic of Korea. Strain HS21 features a 7,059,027 bp circular chromosome with 44.8% GC-content. Its genome contains 5,939 protein-coding genes, 78 transfer RNA (tRNA) genes, 27 ribosomal RNA (rRNA) genes, 4 noncoding RNA genes (ncRNA), and 90 pseudogenes. The bacterium contains antibiotic-related gene clusters and genes encoding plant cell wall-degrading enzymes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.125-136
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• 2011

The vulnerabilities existed in Korean electricity control systems is unexposed because it is being operated in a closed network with superior security. The threat will become greater once the closed network develops into a smart grid environment with superior intelligence. Security will have a greater impact once each household will be connected to the power plant via the smart meter. This research focuses on stable data transfer in harsh external environment and whole-nation coverage network, and suggested standardized and optimized Virtual Private Network (VPN) Gateway architecture to support Power Line Communication (PLC). The functionality and stability of the prototype has been verified with field tests. For implementation of outdoor type VPN device for smart grid, we adopted PLC low voltage remote-meter-net for data communication. Also, IPSec type tunneling and ARIA algorithm based encryption of data collected by PLC low voltage remote meter is transmitted.

• The Journal of Bigdata
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• v.5 no.2
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• pp.145-153
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• 2020

This study was conducted with funding from the government (Ministry of Agriculture, Food and Rural Affairs) in 2018 with support from the Agricultural, Food, and Rural Affairs Agency, 318069-03-HD040, and is based on artificial intelligence-based HPAI spread analysis and patterning. Highly Pathogenic Avian Influenza (HPAI) is coming from abroad through migratory birds, but it is not clear exactly how it spreads to farms. In addition, it is assumed that the main cause of the spread is the vehicle, but the main cause of the spread is not exactly known. However, it is necessary to analyze the relationship between the vehicles and the facilities at the farms where they occur, as the type of vehicles that visit the farms most frequently is between farms and facilities, such as livestock transportation and feed transportation. In this paper, based on the Korea Animal Health Integrated System (KAHIS) data provided by Animal and Plant Quarantine Agency, the main cause of HPAI virus transfer is to be confirmed between vehicles and facilities.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.67-72
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• 2021

BACKGROUND: Biological iron redox transformation alters iron minerals, which may act as effective adsorbents for arsenate [As(V)] in the environments. In the viewpoint of alleviating arsenate, microbial Fe(III) reduction was sought under high concentration of As(V). In this study, Fe(III)-reducing bacteria were isolated from the wild plant rhizosphere soils collected at abandoned mine areas, which showed tolerance to high concentration of As(V), in pursuit of potential agents for As(V) bioremediation. METHODS AND RESULTS: Bacterial isolation was performed by a series of enrichment, transfer, and dilutions. Among the isolated strains, two strains (JSAR-1 and JSAR-3) with abilities of tolerance to 10 mM As(V) and Fe(III) reduction were selected. Phylogenetic analysis using 16S rRNA genesequences indicated the closest members of Pseudomonas stutzeri DSM 5190 and Paenibacillus selenii W126, respectively for JSAR-1 and JSAR-3. Ferric and ferrous iron concentrations were measured by ferrozine assay, and arsenic concentration was analyzed by ICP-AES, suggesting inability of As(V) reduction whereas ability of Fe(III) reduction. CONCLUSION: Fe(III)-reducing bacteria isolated from the enrichments with arsenate and ferric iron were found to be resistant to a high concentration of As(III) at 10 mM. We suppose that those kinds of microorganisms may suggest good application potentials for As(V) bioremediation, since the bacteria can transform Fe while surviving under As-contaminated environments. The isolated Fe(III)-reducing bacterial strains could contribute to transformations of iron minerals which may act as effective adsorbents for arsenate, and therefore contribute to As(V) immobilization

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2387-2395
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• 2021

Seismic qualifications of electrical equipment, such as cabinet systems, have been emerging as the key area of nuclear power plants in Korea since the 2016 Gyeongju earthquake, including the high-frequency domain. In addition, electrical equipment was sensitive to the high-frequency ground motions during the past earthquake. Therefore, this paper presents the rocking behavior of the electrical cabinet system subjected to Reg. 1.60 and UHS. The high fidelity finite element (FE) model of the cabinet related to the shaking table test data was developed. In particular, the first two global modes of the cabinet from the experimental test were 16 Hz and 24 Hz, respectively. In addition, 30.05 Hz and 37.5 Hz were determined to be the first two local modes in the cabinet. The high fidelity FE model of the cabinet using the ABAQUS platform was extremely reconciled with shaking table tests. As a result, the dynamic properties of the cabinet were sensitive to electrical instruments, such as relays and switchboards, during the shaking table test. In addition, the amplification with respect to the vibration transfer function of the cabinet was observed on the third floor in the cabinet due to localized impact corresponding to the rocking phenomenon of the cabinet under Reg.1.60 and UHS. Overall, the rocking of the cabinet system can be caused by the low-frequency oscillations and higher peak horizontal acceleration.