• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.483-489
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• 2006

The behavior of rare earth compounds such as $La_{2}O_{3}$, $CeO_{2}$, and $Ca(OH)_{2}$ on the removal of fluoride and heavy metals in the steel wastewater has been investigated. The removal mechanism of fluoride by rare earth elements has been known to be the formation of insoluble compounds between $F^{-}$ and cations such as $La^{3+}$ and $Ce^{4+}$ produced by the dissociation of rare earth compounds (To reduce the running cost of the fluoride wastewater treatment facility, their fluoride removal efficiencies were compared with those of inexpensive rare earth minerals such as natural lanthanide and cerium compound used as a glass polishing agent). All of the rare earth oxides used in this study showed a higher removal efficiency of fluoride than $Ca(OH)_{2}$ in the wastewater. In the case of artificial HF solution, the removal efficiency of fluoride showed in the order: $CeO_{2}$-mineral < $CeO_{2}$ < $Ca(OH)_{2}$ < $La_{2}O_{3}$-mineral < $La_{2}O_{3}$. However, the removal efficiency of fluoride in the wastewater increased in the following order: $Ca(OH)_{2}$ < $CeO_{2}$ mineral < $CeO_{2}$ < $La_{2}O_{3}$ mineral < $La_{2}O_{3}$. All agents showed high efficiencies for the removal of Mn and total Cr in the rare earth compounds. In the case of $Ca(OH)_{2}$, fluoride removal decreased with increasing pH while. However, the rare earth compounds showed a higher fluoride removal in higher pH condition, the optimum pH condition seemed to be around 7 considering both water quality and fluoride removal. Under the pH 7 condition, the $Ca(OH)_{2}$ was superior to rare earth compounds in Mn removal and the lanthanide was superior to others in total Cr removal.

• Clean Technology
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• v.28 no.1
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• pp.63-78
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• 2022

Electronics industrial wastewater treatment facilities release organic wastewaters containing high concentrations of organic pollutants and more than 20 toxic non-biodegradable pollutants. One of the major challenges of the fourth industrial revolution era for the electronics industry is how to treat electronics industrial wastewater efficiently. Therefore, it is necessary to develop an electronics industrial wastewater modeling technique that can evaluate the removal efficiency of organic pollutants, such as chemical oxygen demand (COD), total nitrogen (TN), total phosphorous (TP), and tetramethylammonium hydroxide (TMAH), by digital twinning an electronics industrial organic wastewater treatment facility in a cyber physical system (CPS). In this study, an electronics industrial wastewater activated sludge model (e-ASM) was developed based on the theoretical reaction rates for the removal mechanisms of electronics industrial wastewater considering the growth and decay of micro-organisms. The developed e-ASM can model complex biological removal mechanisms, such as the inhibition of nitrification micro-organisms by non-biodegradable organic pollutants including TMAH, as well as the oxidation, nitrification, and denitrification processes. The proposed e-ASM can be implemented as a Water Digital Twin for real electronics industrial wastewater treatment systems and be utilized for process modeling, effluent quality prediction, process selection, and design efficiency across varying influent characteristics on a CPS.

• Korean Journal of Heritage: History & Science
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• v.37
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• pp.285-307
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• 2004

Synthesize and examine petrological characteristic and geochemical characteristic by weathering formation of rock and progress of weathering laying stress on stone cultural properties of Unjusa temple of Chonnam Hwasun county site in this research. Examine closely weathering element that influence mechanical, chemical, mineralogical and physical weathering of rocks that accomplish stone cultural properties and these do quantification, wish to utilize by a basic knowledge for conservation scientific research of stone cultural properties by these result. Enforced component analysis of rock and mineralogical survey about 18 samples (pyroclastic tuff; 7, ash tuff; 4, granite ; 4, granitic gneiss; 3) all to search petrological characteristic and geochemical characteristic by weathering of Unjusa temple precinct stone cultural properties and recorded deterioration degree about each stone cultural properties observing naked eye. Major rock that constitution Unjusa temple one great geological features has strike of N30-40W and dip of 10-20NE being pyroclastic tuff. This pyroclastic tuff is ranging very extensively laying center on Unjusa temple and stone cultural properties of precinct is modeled by this pyroclastic tuff. Stone cultural propertieses of present Unjusa temple precinct are accomplishing structural imbalance with serious crack, and because weathering of rock with serious biological pollution is gone fairly, rubble break away and weathering and deterioration phenomenon such as fall off of a particle of mineral are appearing extremely. Also, a piece of iron and cement mortar of stone cultural properties everywhere are forming precipitate of reddish brown and light gray being oxidized. About these stone cultural properties, most stone cultural propertieses show SD(severe damage) to MD(moderate damage) as result that record Deterioration degree. X-ray diffraction analysis result samples of each rock are consisted of mineral of quartz, orthoclase,plagioclase, calcite, magnetite etc. Quartz and feldspar alterated extremely in a microscopic analysis, and biotite that show crystalline form of anhedral shows state that become chloritization that is secondary weathering mineral being weathered. Also, see that show iron precipitate of reddish brown to crack zone of tuff everywhere preview rock that weathering is gone deep. Tuffs that accomplish stone cultural properties of study area is illustrated to field of Subalkaline and Peraluminous, $SiO_2$(wt.%) extent of samples pyroclastic tuff 70.08-73.69, ash tuff extent of 70.26-78.42 show. In calculate Chemical Index of Alteration(CIA) and Weathering Potential Index(WPI) about major elements extent of CIA pyroclastic tuff 55.05-60.75, ash tuff 52.10-58.70, granite 49.49-51.06 granitic gneiss shows value of 53.25-67.14 and these have high value gneiss and tuffs. WPI previews that is see as thing which is illustrated being approximated in 0 lines and 0 lines low samples of tuffs and gneiss is receiving esaily weathering process as appear in CIA. As clay mineral of smectite, zeolite that is secondary weathering produce of rock as result that pick powdering of rock and clothing material of stone cultural properties observed by scanning electron micrographs (SEM). And roots of lichen and spore of hyphae that is weathering element are observed together. This rock deep organism being coating to add mechanical weathering process of stone cultural properties do, and is assumed that change the clay mineral is gone fairly in stone cultural properties with these. As the weathering of rocks is under a serious condition, the damage by the natural environment such as rain, wind, trees and the ground is accelerated. As a counter-measure, the first necessary thing is to build the ground environment about protecting water invasion by making the drainage and checking the surrounding environment. The second thing are building hardening and extirpation process that strengthens the rock, dealing biologically by reducing lichens, and sticking crevice part restoration using synthetic resin. Moreover, it is assumed to be desirable to build the protection facility that can block wind, sunlight, and rain which are the cause of the weathering, and that goes well with the surrounding environment.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.69-74
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• 2013

This study has been performed for 150 days from February 1 - June 31, 2012 aiming at analyzing biologically hazardous factors in order to develop HACCP system for the vinegared pickle radishes. A process chart was prepared as shown on Fig. 1 by referring to manufacturing process of manufacturer of general vinegared pickle radishes regarding process of raw agricultural products of vinegared pickle radishes, used water, warehousing of additives and packing material, storage, careful selection, washing, peeling off, cutting, sorting out, stuffing (filling), internal packing, metal detection, external packing, storage and consignment (delivery). As a result of measuring Coliform group, Staphylococcus aureus, Salmonella spp., Bacillus cereus, Listeria Monocytogenes, E. coli O157:H7, Clostridium perfringens, Yeast and Mold before and after washing raw radishes, Bacillus cereus was $5.00{\times}10$ CFU/g before washing but it was not detected after washing and Yeast and Mold was $3.80{\times}10^2$ CFU/g before washing but it was reduced to 10 CFU/g after washing and other pathogenic bacteria was not detected. As a result of testing microorganism variation depending on pH (2-5) of seasoning fluid (condiment), pH 3-4 was determined as pH of seasoning fluid as all the bacteria was not detected in pH3-4. As a result of testing air-borne bacteria (number of general bacteria, colon bacillus, fungus) depending on each workplace, number of microorganism of internal packing room, seasoning fluid processing room, washing room and storage room was detected to be 10 CFU/Plate, 2 CFU/Plate, 60 CFU/Plate and 20 CFU/Plate, respectively. As a result of testing palm condition of workers, as number of general bacteria and colon bacillus was represented to be high as 346 $CFU/Cm^2$ and 23 $CFU/Cm^2$, respectively, an education and training for individual sanitation control was considered to be required. As a result of inspecting surface pollution level of manufacturing facility and devices, colon bacillus was not detected in all the specimen but general bacteria was most dominantly detected in PP Packing machine and Siuping machine (PE Bulk) as $4.2{\times}10^3CFU/Cm^2$, $2.6{\times}10^3CFU/Cm^2$, respectively. As a result of analyzing above hazardous factors, processing process of seasoning fluid where pathogenic bacteria may be prevented, reduced or removed is required to be controlled by CCP-B (Biological) and threshold level (critical control point) was set at pH 3-4. Therefore, it is considered that thorough HACCP control plan including control criteria (point) of seasoning fluid processing process, countermeasures in case of its deviation, its verification method, education/training and record control would be required.

• Journal of Animal Environmental Science
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• v.14 no.2
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• pp.129-138
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• 2008

This study was carried out to investigate the operating characteristics, water balance and chemical properties of compost during the composting with pig slurry on-farm trial. The composting plant with sawdust pile filteration was done in a forced aeration inside a house and equipped with a turning machine moving on a rails. The composting pit was 4.6m wide, 53m long and the maximum height was 2m. A field scale aerobic composting facility was tested the composting efficiency of high moisture pig slurry. The sawdust materials remained 6 months. Pig slurry was added to compost pile every other day during 6 months run. The temperature in compost pile and compost house, and input and output of moisture were measured during composting process. The result are summarized as follows; 1. The temperature of compost was varied in range of at $22.4^{\circ}C{\sim}71.1^{\circ}C$. After turning, the composting temperature decreased to $50^{\circ}C{\sim}36^{\circ}C$ during $3{\sim}5$ hours, and then raised to $64.5^{\circ}C$ 2. The temperature of compost house was maintained $20^{\circ}C{\sim}30^{\circ}C$, and relative humidity was varied in range of $50{\sim}99%$. 3. BOD, CODcr and SS of leachate water was reduced 89.5%, 81.2%, 97.5%, respectively. 4. The content of heavy metal in the final compost was lower those of Korea standards. 5. The amount of effluent was 10.2%. Total evaporation during composting Period were 74.8%. The amount of slurry per $1m^3$ sawdust was $3.16m^3$ without treatment of effluent output.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.394-401
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• 2005

A nonthermal plasma-assisted fuel reformer was developed and the effects of operating variables on the performance of this reformer were studied. The $H_2$-rich reformed gas from the reformer was injected into a diesel engine under an idle condition and the effects of the amount of injected gas on the NO and soot reduction were investigated. It was found that with increasing electric power consumption, the degree of facility of ignition of the reforming reaction in the reformer could be enhanced. The performance of the reformer including $H_2$ concentration, $H_2$ recovery, and energy conversion was affected only by the O/C mole ratio. This was because the equilibrium reaction temperature was governed by the O/C mole ratio. With increasing O/C mole ratio, the $H_2$ recovery and energy conversion passed through the maximum values of 33.4% and 66%, respectively, at an O/C mole ratio between 1.2 and 1.5. The reason why the $H_2$ recovery and energy conversion increased with increasing O/C mole ratio when the O/C mole ratio was lower than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction occurred more enough with increasing O/C mole ratio in this low O/C mole ratio range and accordingly the reaction temperature increased. Whereas the reason why the $H_2$ recovery and energy conversion decreased with increasing O/C mole ratio when the O/C mole ratio was higher than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction was further advanced and the $H_2$ recovery and energy conversion decreased. As the weight ratio of reformed diesel to total diesel which entered the diesel engine was increased to $18.2{\sim}23.5%$, NO and soot reduction efficiencies increased and reached as values high as 68.5% and 23.5%, respectively.

• Analytical Science and Technology
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• v.29 no.3
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• pp.114-125
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• 2016

In this study, 165 wastewater discharge facilities in 10 business types were investigated with regard to 24 specific hazardous substances that included heavy metals, VOCs, CN, and phenol in the Gwangju city. Cu in the range from from 0.008 to 35.420 mg/L was detected in all business types and the detection rate was 46.8 %. Other heavy metals, such as Cd, As, Hg, Pb, and Cr⁺⁶ were detected as well. However, their detection rates ranged between 0.6 and 1.8 %. CN and phenol were detected in one and five facilities, respectively. 12 species of VOCs were detected: chloroform 80.6 % (0.42 to 81.60 μg/L), benzene 16.4 % (1.49 to 3.31 μg/L), trichloroethylene 11.5 % (1.78 to 6.02 μg/L), 1,1-dichloroethylene 10.3 % (1.23 to 5.89 μg/L), and dichloromethane 8.5 % (0.28 to 968.86 μg/L) in the detection rate order. The concentration of VOCs was detected in trace amounts, except for dichloromethane that exceeded the effluent quality standard in three business types, namely, metal manufacturing, food industry, and car washing facility. Chloroform was detected in all business types, where 24.88 μg/L were detected in the laundry business and 53.41 μg/L in the water supply business; the mean concentration of chloroform in these two business types was higher than elsewhere. Therefore, for the disposal of non-degradable specific hazardous substances in industrial wastewater, it is necessary to introduce physical and chemical processes, such as activated carbon adsorption, fenton oxidation, ozone treatment, as well as photocatalyst and the UV radiation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.302-307
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• 2002

To investigate difference of components changes in salt-fermented anchovy, Engaulis japonicus sauce during 18 months fermentation by tank size, various chemical properties were examined at 2$\~$3 months intervals. The contents of total and amino nitrogen, total ATP related compounds increased gradually during 18 months of fermentation, and showed higher content in salt-fermented anchor sauce produced by large tank scale (LTS) product than those of small tank scale (STS) product during fermentation. Hypoxanthine and uric acid were the most abundant in ATP related compounds, ranging from $81.1\%$ to $90.4\%$, The cross point of inosine (HxR) + hypoxanthine (Hx) and uric acid was faster in LTS with 10.3 months fermentation than in STS with 12.6 months fermentation. After 18month of fermentation, the LTS was rich in free amino acids, such as glutamic acid, alanine, aspartic acid, valine, Iysine in that order. On the other hand, the STS was rich in free amino acids, glutamic acid, aspartic acid, alanine, vsine, valine in that order. Absorbance at 453 nm were higher in STS than in STS, but was no difference the rate of increase during fermentation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.449-469
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• 2011

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering during 2010. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends of thermal and fluid engineering have been surveyed as groups of general thermal and fluid flow, fluid machinery, and new and renewable energy. Various topics were presented in the field of general thermal and fluid flow. Research issues mainly focused on the thermal reliability of axial fan and compressor in the field of fluid machinery. Studies on the design of ground source heat pump systems and solar chemical reactors were executed in the field of new and renewable energy. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (3) Refrigeration systems with alternative refrigerants such as hydrocarbons, mixed refrigerants, and CO2 were studied. Performance improvement of refrigeration systems are tried applying various ideas of refrigerant subcooling, dual evaporator with hot gas bypass control and feedforward control. The hybrid solar systems combining the solar collection devices with absorption chillers or compression heat pumps are simulated and studied experimentally as well to improve the understanding and the feasibility for actual applications. (4) Research trend in the field of mechanical building facilities has been found to be mainly focused on field applications rather than performance improvements. Various studies on heating and cooling systems, HVAC facilities, indoor air environments and energy resources were carried to improve the maintenance and management of building service equipments. In the field of heating and cooling systems, papers on a transformer cooling system, a combined heat and power, a slab thermal storage and a heat pump were reported. In the field of HVAC facilities, papers on a cooling load, an ondol and a drying were presented. Also, studies on HVAC systems using unutilized indoor air environments and energy resources such as air curtains, bioviolence, cleanrooms, ventilation, district heating, landfill gas were studied. (5) In the field of architectural environment and energy, studies of various purposes were conducted such as indoor environment, building energy, renewable energy and green building. In particular, renewable energy and building energy-related researches have mainly been studied reflecting the global interest. In addition, many researches which related the domestic green building certification of school building were performed to improve the indoor environment of school.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.95-111
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• 2004

This research sought to determine the status of the installation and operation of composting facilities of domestic public resource-making facilities and come up with corresponding improvement measures. The composting facilities were the most extensively installed of related facilities with over a 0.5 ton treated volume per day. The monthly and yearly carry-in volume of food waste were found to stand at 1,101.7 tons per day and 930.9 tons per day, thus falling short of the average planned volume of 1,270.9 tons. Many composting facilities, which were installed in areas for which factory registration were not approved, did not get approvals. Composting facilities underwent operation stoppage mainly due to faulty fermentation and crushing equipment. Mainly metals contained in food waste caused faults to the crushing equipment, thus requiring a facility designing against faults and corrosion. The initial water content was found to stand at 50-60%, thus complying with the requirement. However, since the composting food waste had an appropriate mixture of sawdust, food waste, and returned compost, it should meet the initial conditions. For fermentation facilities, the duration time for fermentation was 15 days, and post-fermentation tanks required 21 days of duration time, thus establishing the minimum criteria. However, some facilities did not meet the requirements, taking more time in decomposition, thus suggesting a need to determine the duration time according to facilities. In composting food waste, microorganism-based thermal oxidizer-operated fermentation tanks should be used to ensure an economic operation. On the contrary, 14 out of 25 survey targets heated fermentation tanks in any form. These thermal facilities contain the growth of bacteria, lowering chemical reaction in composting; thus composting facilities should be basically designed to use microorganism-based thermal oxidizers in drying water. An average daily volume of food waste and supplementary materials that was injected in producing compost was 22.8 tons. This volume produced 7.3 tons of compost per day, decreasing 68%. Properties of produced compost were analyzed by its color, absence or presence of remaining decomposition heat, and smell, to assess the quality. As a result, the composting process was not properly installed nor operated in about 50% of composting facilities. Compost should be produced to be soil-friendly.