• Korean journal of food and cookery science
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• v.13 no.3
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• pp.293-298
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• 1997

The changes of microorganisms, pH, color and flavor were examined in the chicken treated with O％, 1%, 2%, and 3% lactic acid solutions during the storage at 4$^{\circ}C$. Lactic acid treatment inhibited the growth of mesophiles, psychrotrophs, and enteric bacilli as the concentration increased, however, it was not effective on yeasts and molds. Extension of lag phase for mesophilic bacteria and suppression of log phase for psychrotrophs and enteric bacilli were observed in the growth inhibition patterns. The pH of the chicken increased during the storage and antimicrobial effect of lactic acid appears to be due to mainly the decrease of pH. No flavor change of the chicken was observed by any lactic acid treatment, however, 3％ lactic acid caused discoloration of the chicken.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.343-348
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• 2011

Since 2005, food waste has been separately collected and recycled to animal feed or aerobic compost in South Korea. However, the conventional recycling methods discharge process wastewater, which contain pollutant equivalent to more than 50% of food waste. Therefore, anaerobic digestion is considered as an alternative recycling method of food waste to reduce pollutant and recover renewable energy. Recent studies showed that hydrogen can be produced at acidogenic stage in two-stage anaerobic digestion. In this study, the authors investigated the effects of pretreatment time and pH low set value on continuous mesophilic hydrogen fermentation of food waste. Food waste was successfully converted to $H_2$ when heat-treated at $70^{\circ}C$ for 60 min, which was milder than previous studies using pH 12 for 1 day or $90^{\circ}C$. Organic acid production dropped operational pH below 5.0 and caused a metabolic shift from $H_2/butyrate$ fermentation to lactate fermentation. Therefore, alkaline addition for operational pH at or over 5.0 was necessary. At pH 5.3, the result showed that the maximum hydrogen productivity and yield of 1.32 $m^3/m^3$.d and 0.71 mol/mol $carbohydrate_{added}$. Hydrogen production from food waste would be an effective technology for resource recovery as well as waste treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1638-1641
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• 2005

In order to develop novel food products or additives using transglutaminase (TGase), some physicochemical and morphological understandings are needed. Raw skim milk was adjusted to pH 5.5, 7.0, and 8.5, and each was treated with microbial TGase for 0, 1, 2, 4, and 8 hours, for the protein structure observation using scanning electron microscope (SEM), The particles of untreated raw skim milk were small and evenly associated. After adjustment of pH to 5.5 and treatment of TGase for 1-hour, the protein particles aggregated widely in a bigger form than that of control. Under the same condition for 2 hours, the particles associated and clustered. The particles gathered widely and became a number of small spherical forms after 4 hours. After 8 hours, they made larger forms than the result of 1-hour treatment, and the aggregation broadened. Under the pH 7.0 and 8.5 conditions with TGase-treatment, the protein Particles fractionated and associated into the bigger masses at 1 hour point, but each piece slowly became smaller and more fractionated until treated time reached 4 hours. After 8 hours, the fragmented protein particles aggregated into larger forms as those on the pH 5.5 condition. In general, the electron microscopical forms of the samples adjusted to pH 5.5 showed smaller than those of pH 7.0 or pH 8.5, It is suggested that the protein particles and textural behavior were influenced by pH, TGase, and reaction time.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.145-152
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• 1998

We conducted this study as a fundamental study on the response of various tree species against acid rain. The tree species used for this study were Zelkova serrata, Robinia pseudoacacia, Quercus acutissima, Prunus serrulata, Ginkgo biloba, Pinus koraiensis and Pinus densiflora. The leaves were examined for the pH changes by treatment time and the chlorophyll content into various pH solution in vitro. The results obtained were as follows ; 1. When the leaves were immersed in the solution of various pH(pH 3.0-pH 6.0) levels, the pH were changed to species specific pH ranges as pH 5.0~pH 5.5 of Z. serrata, pH 5.5~pH 6.0 of R. pseudoacacia, pH 4.5~pH 5.0 of Q. acutissima, pH 5.5~pH 6.0 of P. serrulata, pH 3.5~pH 4.5 of G. biloba, pH 3.5~pH 4.5 of P. koraiensis until 48 hours. However, in case of P. densiflora, it was difficult to find specific pH range of the species. Z. serrata, R. pseudoacacia and P. serrulata showed a little pH increasing by pH 2.0 solution treatment, while other species showed no change by the solution. 2. The amount of chlorophyll contents in Z. serrata, R. pseudoacacia and P. serrulata were decreased after immersing in the pH 2.0 solution. Chlorophyll content was almost constant in other pH levels. Other species showed almost constant chlorophyll contents in various pH levels and treatment time.

• Resources Recycling
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• v.15 no.3 s.71
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• pp.58-65
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• 2006

The applicability of the waste pulp which produced in the paper recycling process as an adsorbent for the treatment of $Ni^{2+}$ ion in wastewater has been investigated taking the initial concentration of adsorbate, temperature, the amount of adsorbent, and solution pH as the experimental variables. In addition, the effect of the concentration of coexisting solute and pre-treatment of adsorbent on the adsorbability of $Ni^{2+}$ ion were also examined. The electrokinetic potential of waste pulp was observed to be positive below pH 7.8 and negative above this pH. The adsorption reaction of $Ni^{2+}$ ion reached its equilibrium within 4 hours after the reaction was initiated and the adsorbed amount of adsorbate was found to increase with its initial concentration. The adsorbability of $Ni^{2+}$ was raised with temperature so that its adsorption reaction was considered to be exothermic, which was substantiated by thermodynamic calculation. Also, the adsorbed amount of $Ni^{2+}$ was raised with the amount of waste pulp and with pH in the range of pH $3{\sim}6$. This behavior of the adsorption of $Ni^{2+}$ according to the solution pH was well agreed with the electrokinetic characteristics of waste pulp in solution. The amount of coexisting solute was observed to reversely affect on the $Ni^{2+}$ adsorption onto waste pulp under the experimental conditions. With regard to the pre-treatment of adsorbent with NaOH, the adsorbability of $Ni^{2+}$ was increased with the concentration of NaOH to a certain extent. However, it was found to decrease contrarily when the concentration of NaOH became too high.

• Korean Journal of Materials Research
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• v.32 no.9
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• pp.361-368
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• 2022

The overall process, from the pre-treatment of aluminum substrates to the eco-friendly neutral electroless Ni-P plating process, was observed, compared, and analysed. To remove the surface oxide layer on the aluminum substrate and aid Ni-P plating, a zincation process was carried out. After the second zincation treatment, it was confirmed that a mostly uniform Zn layer was formed and the surface oxide of aluminum was also removed. The Ni-P electroless plating films were formed on the secondary zincated aluminum substrate using electroless plating solutions of pH 4.5 and neutral pH 7.0, respectively, while changing the plating bath temperature. When a neutral pH7.0 electroless solution was used, the Ni-P plating layer was uniformly formed even at the plating bath temperature of 50 ℃, and the plating speed was remarkably increased as the bath temperature was increased. On the other hand, when a pH 4.5 Ni-P electroless solution was used, a Ni-P plating film was not formed at a plating bath temperature of 50 ℃, and the plating speed was very slow compared to pH 7.0, although plating speed increased with increasing bath temperature. In the P contents, the P concentration of the neutral pH 7.0 Ni-P electroless plating layer was reduced by ~ 42.3 % compared to pH 4.5. Structurally, all of the Ni-P electroless plating layers formed in the pH 4.5 solution and the neutral (pH 7.0) solution had an amorphous crystal structure, as a Ni-P compound, regardless of the plating bath temperature.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.250-256
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• 2005

This study was aimed to investigate treatment feasibility of leachate from D landfill that is located in gyr대ungbuk. From the analytical results of leachate, organic and nonbiodegradable matters were contained in high concentration. Thus chemical treatment was introduced to degrade nonbiodegradable matters in pre or post biological process. Two types of Fenton oxidation were adapted in this study. The first one is pre treatment process before biological treatment. The second one is post treatment process after biological treatment. The optimal conditions of both treatment methods were investigated as follows. In case of pre treatment process, the optimal conditions appeared in $Fe^{+2}/H_2O_2$(mmol/mmol): 0.1, $H_2O_2/CODcr$(mg/mg): 27.0, pH: 3 and reaction time: 2hrs. On the other hand, in case of post treatment process, the optimal conditions appeared in $Fe^{2+}$(mmol/mmol): 0.14, $H_2O_2/COD_{cr}$(mg/mg): 57.4, pH: 3 and reaction time: 1.25hrs. In the above optimal conditions, high COD removal was obtained in pre and post treatment process. Also it can expect that Fenton oxidation converted nonbiodegradable matters into biodegradable matters.

• Food Science of Animal Resources
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• v.26 no.3
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• pp.356-361
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• 2006

This study was carried out to investigate the physico-chemical and storage characteristics of sausages added mugwort powder at $4^{\circ}C$ during 13 days. The composition of fresh sausages was as the following : meat 60 % (w/w), lard 20 %, ice 20 %, salt 1.5 %, sugar 0.5 %, phosphate 0.25 %, mugwort 2 % or 5 %. Sausages were divided into three groups; control group mugwort 0 %, Treatment I mugwort 2 % and Treatment II mugwort 5 %. The pH, TBA(thiobarbituric aid) value, VBN(volatile basic nitrogen), rheology, and sensory evaluation were measured. The changes of pH of all groups were slightly decreased with increasing storage days. But, the significant difference of pH changes were not shown between mugwort 2 % (Treatment I) and mugwort 5 % (Treatment II) groups. The changes of TBA values of all treatments increased during storage periods. TBA values of Treatment I and Treatment II groups were significantly (p<0.05) higher than that of the control group. The change of VBN showed trends to increase during storage periods. The change of VBN of Treatment I was significantly (p<0.05) lower than those of the control and Treatment II. Hardness and brittleness of 2 % and mugwort 5 % groups were significantly (p<0.05) higher than that of the control group. Elasticity and cohesiveness of 2 % and Treatment II were significantly (p<0.05) lower than that of the control group. Also, Treatment I was superior to the other groups by the results of sensory evaluation. Therefore, these results suggest that it may be possible to manufacture sausages added 2 % mugwort powder which can help to increase storage periods, and improve quality of sausage.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.377-384
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• 2005

Algae causes not only the eutrophication of lake, but also the deterioration of drinking water process. Especially, algogenic organic matters(AOM) are assumed as disinfection by-products(DBPs) precursors like humic and fulvic acids. In this study, it was investigated the characteristics changes of algogenic organic matter(AOM) by prechlorination and coagulation treatment. Evaluation of enhanced coagulation and applicability of UV oxidation process were also evaluated as the drinking water treatment system for the eutrophicated water source. prechlorination was effective process for algae removal but caused releasing of dissolved organic matter(DOC) into water due to the destruction of algae's cell. In coagulation treatment with Fe(III) coagulant, reaction pH is an important factor for the removal of AOM and triholomathanes(THMs). At pH 5, removal efficiency of DOC and THMs were dramatically improved by 50% and 28%, respectively, in comparison with the conventional coagulation treatment at about pH 7. Photo-Fenton($UV/H_2O_2/Fe^{3+}$) process among the UV oxidations is the most effective system to remove AOM, but its removal efficiency was lower than that of enhanced coagulation treatment at pH 5.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.34-40
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• 2000

In the tungsten industry, molybdenum wire which used as the center supporter for coil shape tungsten wire was removed. Nitric acid dissolution method which used prevalently up to the present, takes nitric acid as major component and use noxious material such as sulfuric acid and hydrochloric acid remove molybdenum wire which used as center supporter by dissolve selectively within the range of no damage on tungsten wire. Mixed acid waste water occurred to the process were difficult to be decomposed by the conventional methords. This mixed acid waste water was treated by ozone, and It was obtained using possible by-product through the treatment waste water. For the three reactors with the same volume ; Blank reactor, Disturbance plate reactor, Packed-bed reactor ; the results were as follows : For the blank reactor COD removal efficiency in the pH = 4 (HRT : 6hr) was 28.5%, COD removal efficiency in the pH = 7 (HRT : 6hr) was 28.6%, and COD removal efficiency in the pH = 10 (HRT : 6hr) was 27.8%. For the disturbance plate reactor COD removal efficiency in the pH = 4 (HRT : 6Min.) was 86.5%, COD removal efficiency in the pH =7 (HRT : 6Min.) was 84.4%, and COD removal efficiency in the pH = 10 (HRT : 60Min.) was 86.8%. For the packed-bed reactor COD removal efficiency in the pH = 4 (HRT : 40Min.) was 76.0%, COD removal efficiency in the pH = 7 (HRT : 40Min.) was 81.3%, and COD removal efficiency in the pH = 10 (HRT : 40Min.) was 84.6%. After O3 treatment using possible by-product(Na2SO4) was 150g/ℓ.