• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.11
• /
• pp.855-859
• /
• 2011

The main pollutants from zirconium alloy tubing manufacturing process in nuclear industry are nitrate ($NO_3-N$) and fluoride (F-)Nitric acid, and hydrofluoric acid is used for acid pickling. The process for the removal of nitrate and fluoride is composed of 1st chemical coagulation, SOD (Sulfur Oxidation Denitrification) process using sulfur-oxidizing denitrification, and 2nd chemical coagulation. The characteristic of the wastewater treatment is an application of SOD process. The SOD Process is highly received attention because it is significantly different from existing processes for sulfur denitrification. A JSC (JeonTech-Sulfur- Calcium) Pellet is unification of sulfur and alkalinity material. According to result of SOD process in wastewater treatment plant, the removal efficiency of T-N was over 91% and the average concentration of T-N from influent was 147.55 mg T-N/L and that from effluent was 12.72 mg T-N/L. Therefore, SOD process is a useful to remove nitrogen from inorganic industrial wastewater and a new development of microbial activator was shown to be stable for activation of autotrophic bacteria.

• Microbiology and Biotechnology Letters
• /
• v.40 no.1
• /
• pp.30-38
• /
• 2012

We investigated the effects on soil microbial diversity and the growth promotion of red pepper resulting from inoculation with a microbial agent composed of Bacillus subtilis AH18, B. licheniformis K11 and Pseudomonas fluorescens 2112 in a red pepper farming field. Photosynthetic bacteria, Trichoderma spp., Azotobacter spp., Actinomycetes, nitrate oxidizing bacteria, nitrite oxidizing bacteria, nitrogen fixing bacteria, denitrifying bacteria, phosphate solubilizing bacteria, cellulase producing bacteria, and urease producing bacteria are all indicator microbes of healthy soil microbial diversity. The microbial diversity of the consortium microbial agent treated soil was seen to be 1.1 to 14 times greater than soils where other commercial agent treatments were used, the latter being the commercial agent AC-1, and chemical fertilizer. The yield of red pepper in the field with the treated consortium microbial agent was increased by more than 15% when compared to the other treatments. Overall, the microbial diversity of the red pepper farming field soil was improved by the consortium microbial agent, and the promotion of growth and subsequent yield of red pepper was higher than soils where the other treatments were utilized.

• Journal of Environmental Health Sciences
• /
• v.34 no.1
• /
• pp.101-107
• /
• 2008

Bio-filtration utilizes microorganisms fixed to a porous medium to metabolize pollutants present in an air stream. The microorganisms grow in a bio-film on the surface of a medium or are suspended in the water phase surrounding the medium particles. Therefore, bio-filter support media play one of the most important key roles in bio-filtration of gas phase pollutants. To characterize and select the appropriate support media, gas adsorption capacity and microorganism immobilization were investigated in lab-scale experiments for the selected target support media which were compost I (compost from lab-scale process), compost II (compost from municipal facility), bark, wood chip, orchid stone and vermiculite. As odor materials, ammonia and trimethylamine were utilized. From the result of experiments, bark was superior to any other support media tested in adsorption capacity as much as 12.5 mg ammonia per 1 g bark. In trimethylamine adsorption, bark and wood chip showed a remarkable results of 21.1 and 14.1 mg/g respectively. On the other hand, microorganism fixation test determined by the count of nitrogen oxidizing microbes population, the compost II and wood chips showed the best results. Considering the characteristics of materials and the operating condition of the bio-filter, bark, wood chip, and compost II are applicable to the support media of bio-filter when they are appropriately blended on the basis of studying the media pH, packing porosity and moisture contents.

• 한국초전도학회:학술대회논문집
• /
• v.9
• /
• pp.388-391
• /
• 1999

Well oriented Bi2212 superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape method in which Cu-free BSCO powder mixture was' printed on copper plate and heat-treated. And we examined the effect of heat-treatment atmosphere for the superconducting properties and microstructure of Bi2212. The composition of Cu-free BSCO powder mixture was Bi$_2O_3$ : SrCO$_3$ : CaCO$_3$ = 1.2~2 : 1 : 1 and the heat-treatment for the superconducting formation reaction was performed in air, oxygen, nitrogen and low oxygen pressure. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Among the nonsuperconducting phases, it is known that the (Sr,Ca)CuO$_3$ phase restrain the formation of the Bi2212 superconducting phase. Because a kind of the nonsuperconducting phases is controled by the oxygen partial pressure, the optimum condition in which the remnants of the second phases don't leave in the fully processed conductor was determined by XRD and the critical tempera to re (Tc) analysis.

• Journal of the Korean Society of Safety
• /
• v.20 no.1 s.69
• /
• pp.18-23
• /
• 2005

This study deals with the friction and wear characteristics of C-N coated SCM415 steel. The PSII(plasma source ion implantation) apparatus was built and a SCM415 test piece with steel substrate was treated with carbon nitrogen by this apparatus. The composition and structure of the surface layer were analyzed and compared with that of PVD(physical vapor decomposition) coated TiN layer. It was found that both of friction coefficient of C-N coating and TiN coating decreased with increasing load, however, C-N coating showed relatively lower faction coefficient than that of TiN coating. The micro-vickers hardness of C-N film is 3200 Hv, which is $32\~43\%$ higher than that of TiN film. The critical load of C-N film is 52N, which is $25\%$ higher than that of TiN film. The hardness of C-N film fabricated by Plasma ion implantation is $61\~70\%$ higher than that of base material, and faction coefficient is $14\~50\%$ lower than that of base material. It is also interesting to note that the friction was changed from adhesive wear mode to light oxidizing wear mode.

• Applied Chemistry for Engineering
• /
• v.25 no.4
• /
• pp.386-391
• /
• 2014

Atmospheric-pressure nonthermal corona discharge plasma was applied to the sterilization of biologically contaminated scoria powder. Escherichia coli (E. coli) culture solution was uniformly sprayed throughout the scoria powder for artificial inoculation, which was well mixed to ensure uniformity of the batch. The effect of the key parameters such as discharge power, treatment time, type of gas and electrode distance on the sterilization efficiency was examined and discussed. The experimental results revealed that the plasma treatment was very effective for the sterilization of scoria powder; 5-min treatment at 15 W could sterilize more than 99.9% of E. coli inoculated into the scoria powder. Increasing the discharge power, treatment time or applied voltage led to an improvement in the sterilization efficiency. The effect of type of gas on the sterilization efficiency was in order of oxygen, synthetic air (20% oxygen) and nitrogen from high to low. The inactivation of E. coli under the influence of corona discharge plasma can be explained by cell membrane erosion or etching resulting from UV and reactive oxidizing species (oxygen radical, OH radical, ozone, etc.), and the destruction of E. coli cell membrane by the physical action of numerous corona streamers.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 1995.11a
• /
• pp.25-25
• /
• 1995

Liquid phase sintering of 90W-6Ni-4Mn alloy has been investigated as functions of sintering atmosphere, heating rate, and reduction temperature. The present work accounts for the thermodynamic oxidatiodreduction reactions of constituent powders of W, Ni and Mn. By discounting these reactions, the previous investigations would obtain only the alloy with large pores and the lowered relative sintered density, by the liquid phase sintering under a dry hydrogen atmosphere. the sintering cycle consisted of a rapid heating to reduction temperatures under high purity nitrogen atmosphere, and holding for 4 hours and sintering at $1260^{\circ}C$ for 1 hour under a dry hydrogen gas. The relative density of the sintered alloy increased with increasing heating rate. As the reduction temperature increased, the relative density increased to the lm theotical density at the duction temture above $1150^{\circ}C$. The mimsturcatre of sintered alloys has been analysed by a scanning election microscope. The sintered density was compared with those obtained from the other investigators. It was found that the reduction $1150^{\circ}C$ results in the lowered densification of 90W-6Ni-4Mn alloy. This is caused by the fact that reducing reactions of W and Ni oxides contained in W an Ni powders concomitantly leads to oxidizing reaction of Mn powder the oxidized Mn is hardly reduced at sintering temperature and thereby remains large pores in the alloy. It is concluded that the W-Ni-Mn alloy with full density can be obtained by the precise control of atmosphere, heating rate, and sintering temperature.

• Animal Bioscience
• /
• v.37 no.1
• /
• pp.123-130
• /
• 2024

Objective: Beef of Jeju black cattle (JBC) is considered as a healthy meat type due to its significantly higher unsaturated fatty acids (UFA). Lipid (e.g., UFA) is highly susceptible to oxidizing agents, which results in the quality deterioration and economic value loss of meat products. Therefore, development and application of novel preservative techniques is necessary to improve the shelf-life stability of high-UFA beef. The objective of this study was to assess the applicability of chitosan-based coatings in preservation of JBC beef. Methods: Different coating solutions: 2% chitosan alone, and 2% chitosan containing 0.1% or 0.3% gallic acid were prepared to investigate their applicability in preservation of fresh beef during storage. Jeju black cattle beef (2-cm thick steaks) were non-coated (control) or coated with the above coating solutions, placed on trays, over-wrapped with plastic film and stored at 4℃. The microbiological indices, color, total volatile basic nitrogen (TVBN) and lipid oxidation of the beef were investigated after 1, 10, and 21 days of storage. Results: Coating with 2% chitosan alone reduced the spoilage bacteria count, TVBN and thiobarbituric acid reactive substances levels in the beef compared with control during storage (p<0.05). Noticeably, coating with 2% chitosan containing 0.1% or 0.3% gallic acid was more effective on retardation of spoilage bacteria growth, lipid oxidation and discoloration in the beef compared to the chitosan coating alone over the storage period (21 days) (p<0.05). Conclusion: Taken together, the combined chitosan and gallic acid coating could be used as a bio-preservative technique in the meat industry.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.9
• /
• pp.939-947
• /
• 2008

PCR-DGGE method was applied to analyze changes of microbial community in simultaneous nitrification and denitrification (SND) bioreactor with various DO concentrations. In the analysis of eubacterial community, band profiles of DGGE were similar with 2 or 1 mg/L DO concentrations in the reactor. Experimental results led to 16 different bacteria being identified, including 5 dominant strains(3 strains of Uncultured Bacterium, 1 strains of Bacillus, 1 strains of Uncultured Bacteroidetes). DGGE results at 0.5 mg/L DO concentration led to 12 strains being identified, including 7 dominant strains(5 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). DGGE results at 0.1 mg/L DO concentration led to 11 strains being identified, including 3 dominant strains(1 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). In DGGE band profiles of $\beta$-AOB($\beta$-Ammonia Oxidizing Bacteria), only one band was observed. This band had 97% similarity with Nitrosomonas sp. done DNB Y20. This band was clearly observed at the 2, 1 and 0.5 mg/L DO concentrations, while the brightness of the band at 0.1 mg/L DO concentration was mostly dimmed. In DGGE band profiles of denitrification process, 5 bands(3 strains of Uncultured organism containing nirS, 2 strains of Uncultured organism containing nirK) were observed. Among those bands, the brightness of one band was gradually increased at the lower DO concentrations. This band has 86% identity with Uncultured organism clone eS1 cd1 nirS gene, partial cds. Based on this result, it could be concluded that Uncultured organism clone eS1 cd1 nirS gene, partial cds is a predominant microorganism in the denitrification process.

• Tuberculosis and Respiratory Diseases
• /
• v.59 no.6
• /
• pp.690-695
• /
• 2005

Nitric acid is an oxidizing agent used in metal refining and cleaning, electroplating, and other industrial applications. Its accidental spillage generates oxides of nitrogen, including nitric oxide (NO) and nitrogen dioxide ($NO_2$), which cause chemical pneumonitis when inhaled. The clinical presentation of a nitric acid inhalation injury depends on the duration and intensity of exposure. In mild cases, there may be no symptoms during the first few hours after exposure, or the typical symptoms of pulmonary edema can appear within 3-24 hours. However, in cases of prolonged exposure, progressive pulmonary edema develops instantaneously and patients may not survive for more than 24 hours. We report a case of a 44-year-old male who was presented with acute respiratory distress syndrome after nitric acid inhalation. He complained of cough and dyspnea of a sudden onset after inhaling nitric acid fumes at his workplace over a four-hour period. He required endotracheal intubation and mechanical ventilation due to fulminant respiratory failure. He was managed successfully with mechanical ventilation using positive end expiratory pressure and systemic corticosteroids, and recovered fully without any deterioration in his pulmonary function.