• Journal of Environmental Science International
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• v.23 no.8
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• pp.1409-1418
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• 2014

Foundry has an important economic value in the industry. However, the generation of air pollutants like particulate and odor are serious. Due to the unavoidable usage of molding sand, particulate occurs in almost all the processes. That accounts for the majority of respirable dust in the size less than $10{\mu}m$ As well as particulate, over 22 species of odor-causing gases and VOCs including hydrogen sulfide and ammonia are occurred. Therefore, the development of equipment that can simultaneously remove TVOC and particulate is regarded as an essential research. In this study, the spraying absorbent system was connected with the shear bag filter for the purpose to remove TVOC and particulate simultaneously. Maximization of process efficiency for the affective factors like the powder combination and injection method is conducted. The experiment was performed at the de-molding process of one foundry plant. Through these devices, the removal efficiency of more than 95% for TVOC was achieved with the absorbent that composed by 800 mesh Activated carbon (80%) and 300 mesh zeolite (20%). Also, the durability and economic evaluation were assessed. In the result of Durability assessment, the available recovery to maintain the deodorizing effect at 90% was counted to 350 degree.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.151-156
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• 2018

As industry and medicine developed, many people became interested in the quality of life. As the concern for health became higher, vegetarian or vegetable oils became more popular than meat. With the development of processes primarily using nickel catalysts today, the shelf life of vegetable oils has increased and mobility has become more convenient. Currently nickel catalysts for the curing of oil are dominated by foreign companies in the world market. On the other hand, the mass production technology of domestic nickel catalyst is backward, and the entire amount is imported from foreign countries. Therefore, there is a need for active research and development of a catalyst that can be commercialized in korea. In this study, nickel as a main active catalyst was used as a base for hydrogen curing reaction, and the effect of rare earth on catalytic activity was investigated. A certain amount of rare earths could induce the dispersion of nickel to increase efficiency and use as co-catalyst.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1500-1509
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• 2020

Drought is a major abiotic factor and has drastically reduced crop yield globally, thus damaging the agricultural industry. Drought stress decreases crop productivity by negatively affecting crop morphological, physiological, and biochemical factors. The use of drought tolerant bacteria improves agricultural productivity by counteracting the negative effects of drought stress on crops. In this study, we isolated bacteria from the rhizosphere of broccoli field located in Daehaw-myeon, Republic of Korea. Sixty bacterial isolates were screened for their growth-promoting capacity, in vitro abscisic acid (ABA), and sugar production activities. Among these, bacterial isolates YNA59 was selected based on their plant growth-promoting bacteria traits, ABA, and sugar production activities. Isolate YNA59 highly tolerated oxidative stress, including hydrogen peroxide (H₂O₂) and produces superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities in the culture broth. YNA59 treatment on broccoli significantly enhanced plant growth attributes, chlorophyll content, and moisture content under drought stress conditions. Under drought stress, the endogenous levels of ABA, jasmonic acid (JA), and salicylic acid (SA) increased; however, inoculation of YNA59 markedly reduced ABA (877 ± 22 ng/g) and JA (169.36 ± 20.74 ng/g) content, while it enhanced SA levels (176.55 ± 9.58 ng/g). Antioxidant analysis showed that the bacterial isolate YNA59 inoculated into broccoli plants contained significantly higher levels of SOD, CAT, and APX, with a decrease in GPX levels. The bacterial isolate YNA59 was therefore identified as Variovorax sp. YNA59. Our current findings suggest that newly isolated drought tolerant rhizospheric Variovorax sp. YNA59 is a useful stress-evading rhizobacterium that improved drought-stress tolerance of broccoli and could be used as a bio-fertilizer under drought conditions.

• Corrosion Science and Technology
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• v.12 no.6
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• pp.280-287
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• 2013

Flow accelerated corrosion(FAC) of the carbon steel piping in pressurized water reactors(PWRs) has been major issue in nuclear industry. Severe accident at Surry Unit 2 in 1986 initiated the worldwide interest in this area. Major parameters influencing FAC are material composition, microstructure, water chemistry, and hydrodynamics. Qualitative behaviors of FAC have been well understood but quantitative data about FAC have not been published for proprietary reason. In order to minimize the FAC in PWRs, the optimal method is to control water chemistry factors. Chemistry factors influencing FAC such as pH, corrosion potential, and hydrazine contents were reviewed in this paper. FAC rate decreased with pH up to 10 because magnetite solubility decreased with pH. Corrosion potential is generally controlled dissolved oxygen (DO) and hydrazine in secondary water. DO increased corrosion potential. FAC rate decreased with DO by stabilizing magnetite at low DO concentration or by formation of hematite at high DO concentration. Even though hydrazine is generally used to remove DO, hydrazine itself thermally decomposed to ammonia, nitrogen, and hydrogen raising pH. Hydrazine could react with iron and increased FAC rate. Effect of hydrazine on FAC is rather complex and should be careful in FAC analysis. FAC could be managed by adequate combination of pH, corrosion potential, and hydrazine.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.70-70
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• 2011

The prospects of current and coming solar-photovoltaic (PV) technologies are envisioned, arguing this solar-electricity source is beyond a tipping point in the complex worldwide energy outlook. Truly, a revolution in both the technological advancements of solar PV and the deployment of this energy technology is underway; PV is no longer an outlier. The birth of modern photovoltaics (PV) traces only to the mid-1950s, with the Bell Telephone Laboratories' development of an efficient, single-crystal Si solar cell. Since then, Si has dominated the technology and the markets, from space through terrestrial applications. Recently, some significant shift toward technology diversity have taken place. Some focus of this presentation will be directed toward PV R&D and technology advances, with indications of the limitations and relative strengths of crystalline (Si and GaAs) and thin-film (a-Si:H, Si, Cu(In,Ga)(Se,S)2, CdTe). Recent advances, contributions, industry growth, and technological pathways for transformational now and near-term technologies (Si and primarily thin films) and status and forecasts for next-generation PV (nanotechnologies and non-conventional and "new-physics" approaches) are evaluated. The need for R&D accelerating the now and imminent (evolutionary) technologies balanced with work in mid-term (disruptive) approaches is highlighted. Moreover, technology progress and ownership for next generation solar PV mandates a balanced investment in research on longer-term (the revolution needs revolutionary approaches to sustain itself) technologies (quantum dots, multi-multijunctions, intermediate-band concepts, nanotubes, bio-inspired, thermophotonics, ${\ldots}$ and solar hydrogen) having high-risk, but extremely high performance and cost returns for our next generations of energy consumers. This presentation provides insights to the reasons for PV technology emergence, how these technologies have to be developed (an appreciation of the history of solar PV)-and where we can expect to be by this mid-21st century.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.419-429
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• 2020

The problems caused by foodborne pathogens are not only a concern to the food industry but also with regard to global public health. Over the years, fermentation technology has proved to be one of the cheapest and safest methods for inactivating and controlling pathogenic microorganisms in food. Scientific evidence shows that lactic acid bacteria fermentation exerts significant antimicrobial effect against pathogenic bacteria and viruses. Lactic acid bacteria metabolites such as organic acids, bacteriocins and hydrogen peroxides have adverse effects on foodborne pathogens which lead to their inhibition. These compounds do not only cause physical injuries, but also have significant effects on the pathogens' gene expression. Furthermore, the presence of lactic acid bacteria in food provides nutritional competition among foodborne pathogens, and all these factors together suppress their growth. This study reviews our current knowledge of the antimicrobial abilities of lactic acid bacteria, their molecular mechanisms, and their application for inactivating foodborne pathogens.

• Journal of Dairy Science and Biotechnology
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• v.36 no.1
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• pp.1-13
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• 2018

Kefir exhibits antimicrobial activity in vitro against gram-positive and gram negative bacteria, as well as some fungi. The ability of LAB to inhibit the growth of closely related bacteria is well known. This inhibition of pathogenic and spoilage microbes may be due to the production of organic acids, hydrogen peroxide, acetaldehyde, diacetyl, carbon dioxide, or bacteriocins. Lactobacilli are the major contributors to acid production and, hence, a determining factor in the flavor development in kefir. Lactic acid, proteolytic activity, and acetaldehyde are the essential flavor compounds in kefir. Both acid and bacteriocins contribute to the antimicrobial activity of kefir and kefir grains. Kefir is rich in proteins, calcium, vitamin $B_{12}$, niacin, and folic acid. Many studies have investigated the benefits of consuming kefir and have shown that it is a natural probiotic, which when consumed regularly, can help relieve intestinal disorders, promote bowel movement, reduce flatulence, and improve the overall health of the digestive system. Tibetan kefir, which is different from traditional kefir, is produced in China. It has been reported to exhibit antimicrobial activity that is nearly identical to that of traditional kefir. Kefir production is considered a rapidly growing food industry in China.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.563-568
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• 2008

In petroleum refining industry, caustic (NaOH) solution is used to remove $H_2S$ from hydrocarbon streams in naphtha cracking process. Once $H_2S$ is absorbed in caustic solution, the solution becomes known as spent sulfidic caustic (SSC), which contains high concentrations of hydrogen sulfide and alkalinity. This study was focused on the evaluation of autotrophic denitrification by SSC in a hybrid Bardenpho process. SSC was injected to the anoxic (1) and anoxic (2) tank at different S/N ratio. In a previous lab-scale study, as we operated a modified Ludzack-Ettinger process, it was observed that the COD increment of effluent and nitrification failure happened because of non-biodegradable matters in SSC and high pH, respectively. Thus cilia media was packed at 2.4%(v/v) in all aerobic tanks and the pH of SSC was neutralized from 13.3 to 11.5 with addition of sulphuric acid ($H_2SO_4$). Consequently, these strategies were successful because no COD increment of effluent was observed and nitrification failure did not happen. The maximum TN removal efficiency was 77.5% when SSC was injected to both the anoxic (1) and anoxic (2) tanks. The mean TN concentration of effluent in this condition was 5.8 mg/L.

• Resources Recycling
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• v.16 no.6
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• pp.28-33
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• 2007

Coal is the most abundant energy source and deposited in every area of world. Combustion process with lower efficiency has been mainly used. Therefore, implementation of more efficient technologies, involving gasification, combined cycles and fuel cells, would be a key issue in the plans for more efficient power generation. In these technologies, gasification has been studied for decades. However, coal gasification to high value combustible gas such as hydrogen and carbon monoxide is focused again due to high oil price. The gaseous product, called syngas, can be effectively utilized in a variety of ways ranging from electricity production to chemical industry (as feedstock). In this study, coal gasification with ultra high temperature steam has been performed. The effect of steam/carbon ratio on the produced gas concentrations, gasification rate and additional products like tar, ammonia and cyan compounds has been determined.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.596-603
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• 2007

Rapid or on-line coal analysis is of great interest in coal industry as it would allow efficient plant operation. Multivariate analysis has been applied to near-infrared(NIR) spectra coal for investigating the relationship between coal properties(%) (moisture, ash, volatile matter, fixed carbon, carbon, hydrogen, nitrogen, oxygen, sulfur), heating value(kcal/kg) and corresponding near-infrared spectral data. The quantitative analysis was carried out by applying PLS(partial least squares regression) to determine a methodology able to establish a relationship between coal properties and NIR spectral data being applied mathematical pre-treatments for minimizing the physical features of the samples. As a results of the analysis, this technique is able to classify the species of coals and to predict the all coal properties except ash, nitrogen and sulfur. The efficient operation of coal fired power plant is expected owing to real time on-line coal analysis of moisture and heating value.