• KSBB Journal
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• v.5 no.2
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• pp.167-173
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• 1990

This study is to investigate for obtaining the operating conditions of continuous vinegar production using fluidized bed reactor by Acetobacter aceti cell immobilized in Ca-alginate gel. The optimum conditions obtaining by batch fermentation using fluidized bed reactor were as follows; The fermentation temperature and aeration rate were 3$0^{\circ}C$ and 1.0VVM and the initial concentration of ethanol and acetic acid in medium were 33g/l and 27g/l respectively. The amount of bead used was 25%(w/v). The overall acetic acid productivities of batch fermentations by free cell and immobilized cell were 0.31g/l-hr and 0.48g/l-hr, respectively, at the final acetic acid concentration of 50g/l. In the continuous vinegar production using fluidized bed reactor by immobilized cell under optimum conditions, it was possible to produce 23g/l acetic acid continuously up to 90 days with maximum acetic acid productivity of 2.76g/l-hr at dilution rate 0.12hr-1.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.369-375
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• 2009

The spot weldability of dissimilar metal joints between stainless steels (AISI316) and interstitial free (IF) steels were investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensileshear strength, hardness, and microstructure. The fracture surface was investigated by using a Scanning Electron Microscopy (SEM). The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the STS316 sheet was larger due to the higher bulk-resistance. The microstructure of the fusion zone was fully martensite. In order to evaluate the microstructure further, dilution of stainless steels were calculated and imposed onto the Schaeffler diagram. The predicted microstructure from the Schaeffler diagram was martensite. In order to confirm the predicted microstructure, XRD measurements were carried out. The results showed that that initial weld nugget was composed of austenite and martensite.

• Journal of Navigation and Port Research
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• v.28 no.10 s.96
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• pp.947-953
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on 'how to dispose the treated municipal water and wastewater in harbor' brings peoples' concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water, CORMIX( Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Journal of Korean Port Research
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• v.11 no.2
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• pp.215-230
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• 1997

A number of ocean outfalls are located around coastal area over the United States and discharge primary treated effluent into deep water for efficient wastewater treatment. Two of them, the Sand Island and Honouliuli municipal wastewater outfalls, are located on the south coast of Oahu. There have been growing interests about the plume dynamics around the ocean outfalls since plume discharged from the multiport diffuser may have significant impacts on coastal communities and immediate consequence on public health. Among the studies of plume dynamics performed in the vicinity of both outfalls, Project MB-4 in the Mamala Bay Study recently made with the funding in the $ 9 million amount statistically dealt with the near-field behavior of the plumes at the Sand Island and Honouliuli outfalls. However, Project MB-4 predicted much higher surfacing frequency than the realistic value obtained by model studies by Oceanit Laboratories, Inc.. It is suggested that improvements should be made in the application of the plume model to more simulate the actual discharge characteristics and ocean conditions. In this study, it has been recommended that input parameters in plume models reflect realistic density profile over the entire water column since. in the previous Mamala Bay Study, the density profiles were measured at 5m depth increments extending from 13 to 63 m depth (the density profile on the upper portion of water column was not included, Roberts 1995). It is proved that the density stratification is the important parameter for the submergence of the plume. In this study, as one of the important parameters, plume rise and initial dilution reflecting the density profile over the entire water column have been taken into account for more reliable plume behavior description.

• Journal of the Korean Institute of Gas
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• v.25 no.2
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• pp.1-12
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• 2021

MILD(Moderate or Intense Low-oxygen Dilution) combustion has attracted attention as the clean thermal energy technology due to the lower emissions of unburnt carbon and NO_x. MILD combustion aims to enlarge the combustion reaction zone using the spontaneous ignition phenomenon of the reactants. In this study, the ignition delay time of CH₄ according to the initial temperature of reactants and the addition of CO, H₂ was investigated using a numerical approach. Ignition delay time became shorter as the increases of initial temperature and H₂ addition. But, CO addition to the fuel increase the ignition delay time. In case of H₂ addition to the fuel, the ignition delay time decreased because the higher fraction of HO₂ promotes the decomposition of methyl radical(CH₃) and produce OH radical. However, in case of CO addition to the fuel, ignition delay time inceased because a high proportion of HCO consumes H radical. There was no significant effect of HCO on the reduction of ignition delay time. Also, the increase rates of NO emissions by the addition of CO and H₂ were approximately 7% and 1%, respectively. A high proportion of NCO affects the increase in NO production rate.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.5
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• pp.377-383
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• 2017

In this research, the improvement of Korean rice wine (makgeolli) with pine (Pinus koraiensis) extract addition was evaluated due to the increase in alcoholic Korean traditional beverage. Makgeolli fermentation was prepared using Korean rice and nuruk (traditional starter) supplemented by pine needle (MPN) and pine sprout (MPS) extract. The average of initial pH level for MPN was 3.95 and MPS was 4.55, the average of initial sugar content for MPN was 0.4% and MPS was 0.3%. The sugar content and pH level behavior were investigated every 24h during fermentation period. The observation of microbial colony was done at days 8 of fermentation period with three time sample dilution. Afterward, the physical appearance of fermentation solution and microbial development were investigated in the final of fermentation period. The number of yeast and LAB ($402{\times}103\;CFU/mL$) in MPN was greater than the yeast and LAB count in MPS ($224{\times}103\;CFU/mL$). The pH level obtained by addition pine sprout have value of R2 higher than addition of pine needles (leaf), the sugar content (%) behaviour was opposite with pH level behaviour.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.29-34
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• 2003

A Pseudomonas sp. strain NGK1 (NCIM 5120) capable of utilizing salicylate was immobilized in alginate and polyurethane foam (PUF). The degradation rate of salicylate by freely suspended cells was compared with the degradation rate by immobilized cells. In an initial 20 and 40 mM salicylate, free cells ($2{\times}10^{11}\;cfu\;ml^{-1}$) degraded to 16 and 14 mM, alginate-entrapped cells degraded to 18 and 26 mM, and PUF-entrapped cells degraded to 20 and 32 mM salicylate, respectively, in batch cultures. The alginate-and PUF-entrapped cells were used in repeated batch and continuous culture systems. The efficiency of both the immobilized systems f3r the degradation of salicylate was compared. It has been observed that the PUF-entrapped cells could be reused for more than 20 cycles whereas alginate-entrapped cells could be reused for a maximum of only 12 cycles, after which a decrease in degradation rat was observed with the initial 20 and 40 mM salicylate. The continuous degradation of sallcylate by freely suspended cells showed a negligible degradation rate of salicylate when compared with immobilized cells. With the immobilized cells in both alginate and polyurethane foam, the degradation rate increased with an increase in the dilution rate up to $2\;h^{-1}$ for 20 mM, and $1.5\;h^{-1}$ for 40 mM salicylate. The results revealed that PUF-entrapped cells were more efficient for the degradation of salicylate than alginate-entrapped cells and freely suspended cells.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.682-689
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• 2010

The purpose of this study was to determine any detrimental effects on surrounding environments by using bottom ash, waste tire, and mixture as a fill material to raise the ground level. Three different initial pHs (4, 6, 8) were applied to bottom ash and initial pH of 4 was used to waste tire and mixture. Among 7 heavy metals, Pb and Zn were exceeded drinking water standards but their concentrations decreased below drinking water standards within 1 PVE. Among 5 anions, sulfate exceeded 10 times of drinking water standards and further higher partition coefficients resulted in increased PVE of 8.21. For the mixture of bottom ash and waste tire, its concentrations of heavy metals and anions were decreased due to the dilution effect and lowered PVE from 8.21 (BA) to 5.89.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.4
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• pp.223-232
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• 1988

Fifty-two wether lambs weighing 30 kg were randomly assigned to 5 treatment groups; 1) initial slaughter. 2) control-maintenance (CON-MT), 3) control-ad libitum (CON-AL), 4) cimaterol-maintenance (CIM-MT) and 5) cimaterol-ad libitum (CIM-AL). Ad libitum-fed animals had free access of a high-concentrate diet, whereas maintenance animals were restricted in feed intake to maintain the initial weight of 30 kg for 90 days. Cimaterol was administered in the feed at 10 mg/kg. Regardless of feeding level, the administration of CIM improved carcass weight (p < .05), dressing % (p < .01), longissimus muscle area (p < .01), leg conformation and muscling (p < .01), USDA yield and quality grades (p < .01) and protein concentration (p < .01) in carcass as well as in muscle. Cimaterol feeding decreased organ wt (p < .01), baekfat depth (p < .01), intramuscular fat and overall fatness. Cimaterol was effective for muscle accretion even under restricted feeding condition. The greater accretion of muscle was the result of the hypertrophy of both type I and type II muscle fibers but the hypertrophy of type II fiber (110%) was much greater than that of type I fiber (37%). Cimaterol feeding decreased muscle DNA concentrations but the number of nuclei per muscle fiber was not changed, indicating that the lower DNA concentration was due to the dilution effect caused by the hypertrophy of muscle fiber. As evidenced by lower flank streaking, lower marbling and darker muscle, CIM feeding adversely affected meat quality. Meat tenderness was also adversely affected, resulting in significantly (p H .01) tougher meat in CIM-fed animals.

• KSBB Journal
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• v.19 no.3
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• pp.236-240
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• 2004

Korean wastewaters have higher nitrogen concentrations than typical wastewaters of other countries. Most treatment processes such as activated sludge processes will need to supplement extra carbon sources for a complete removal of remaining nitrogen after the initial wastewater treatment, Because of these difficult matters, we have searched wastewater treatment methods that require no additional carbon sources. Wastewater treatment by microalgae in photobioreactors, using a green eukaryotic microalgae, Chlorella kessleri, showed a promising results and thus was selected to study further. This system is not intended to replace the conventional system but is to assist the existing biological treatment systems as a supplemental nitrogen removal process. Thus the secondary treated livestock wastewater was tested. Column type photobioreactors developed in our laboratory were used. When aerated with 5% CO$_2$ balanced with air at 1 vvm and illuminated at 100 ${\mu}$mol/㎡/s under 25$^{\circ}C$ and PH 7-8 by CO$_2$ buffering effect, the maximum nitrogen removal rate was 2.6 mg/L/hr. The results confirmed a possibility of microalgal wastewater treatment system as a secondary system to remove extra nitrogen sources. Based on these experimental results, the size of the optimal microalgal wastewater system was calculated. For the wastewater whose initial nitrogen concentration of 150 mg/L, the optimal batch system was found to be a 2 stage system with a combined retention time of 4.6 day. From the continuous experiments, nitrogen removal rates were examined under different dilution rates and 2 stage system was also found to be the optimal system. The combined retention time for the continuous system was 3.5 days. It is expected that conventional biological wastewater treatment systems followed by microalgal systems would reliably decrease the nitrogen concentration below the government criteria even for the livestock wastewater with low C/N ratio.