• 한국양식학회지
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• 제16권4호
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• pp.216-222
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• 2003

In a simulated seawater aquaculture system, effects of different operating factors like the superficial air velocity (SAY), hydraulic residence time (HRT), protein concentration and foam overflow height on the removal of total suspended solids (TSS) by a foam fractionator, with 20 cm diameter and 120 cm height, were investigated. This experiment was performed on batch and consecutive modes for different combinations of the tested factors, using synthetic wastewater. In 5 consecutive trials, TSS concentration in culture tank water decreased faster, when the foam fractionator was operated at higher SAV and lower HRT. In batch trials, with increasing SAV, TSS removal rate increased, but decreased with increasing HRT. Higher protein concentration in the bulk solution resulted in higher TSS removal rate. TSS concentration in the collected foam condensates increased but the foam overflow rate decreased with increasing foam overflow height. Foam fractionation was effective for removing TSS in seawater aquaculture systems and its performance largely depended on the operating parameters, especially superficial air velocity.

• Membrane and Water Treatment
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• 제1권4호
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• pp.297-316
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• 2010

Membrane fouling is one of the major operational concerns of membrane processes which results in loss of productivity. This paper investigates the ultrafiltration (UF) results of synthetic oil-in-water (o/w) emulsion using flat sheets of polysulfone (PSf) membrane synthesized with four different compositions. The aim is to identify the mechanisms responsible for the observed permeate flux reduction with time for different PSf membranes. The experiments were carried out at four transmembrane pressures i.e., 68.9 kPa, 103.4 kPa, 137.9 kPa and 172.4 kPa. Three initial oil concentrations i.e., 75 $mgL^{-1}$, 100 $mgL^{-1}$ and 200 $mgL^{-1}$ were considered. The resistance-in-series (RIS) model was applied to interpret the data and on that basis, the individual resistances were evaluated. The significances of these resistances were studied in relation to parameters, namely, transmembrane pressure and initial oil concentration. The total resistance to permeate flow is found to increase with increase in both transmembrane pressure and initial oil concentration while for higher oil concentration, resistance due to concentration polarization is found to be the prevailing resistance. The applicability of the constant pressure filtration models to the experimental data was also tested to explain the blocking process. The study shows that intermediate pore blocking is the dominant mechanism at the initial period of UF while in the later period, the fouling process is found to approach cake filtration like mechanism. However, the duration of pore blocking mechanism is different for different membranes depending on their morphological and permeation properties.

• Asian-Australasian Journal of Animal Sciences
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• 제13권8호
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• pp.1044-1049
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• 2000

Three wethers fitted with silastic catheters for collection of pancreatic juice, and cannulas located in the abomasum and the duodenum were used to investigate the effects of different hay and energy intake on pancreatic exocrine secretion. The wethers were fed Italian ryegrass hay or alfalfa hay at maintenance energy requirement and alfalfa hay ad libitum. High energy intake from alfalfa significantly increased abomasal flow of dry matter and both the concentration and daily secretion of ${\alpha}-amylase $. The high energy intake also tended to increase daily secretion of lipase, trypsin and chymotrypsin through the large volume of pancreatic juice. Compared with Italian ryegrass hay, alfalfa hay at the maintenance decreased abomasal dry matter flow, but increased concentration of ${\alpha}-amylase $ in the pancreatic juice, and tended to increase daily secretion of ${\alpha}-amylase $. The secretion of the other enzymes was not different between the two hays at maintenance intake. These results suggest that the kind of hay could change the concentration of ${\alpha}-amylase $ in the pancreatic juice, and that the intake level of alfalfa hay affects the ${\alpha}-amylase $ concentration and the juice volume secreted from the pancreas.

• Food Science and Biotechnology
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• 제17권4호
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• pp.850-856
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• 2008

White, red, and extruded ginsengs were studied against 8 strains of food-borne pathogens and/or food spoilage microorganisms. The ginseng powders were extracted with different extractants and screened for antimicrobial activity using the disc diffusion and broth dilution techniques. The results showed that the yield of extraction was higher with increase of aqueous solution content and temperature. Preliminary screening revealed that the red ginseng extracts were most active, that has been found to be highly effective against all tested microbe except Listeria monocytogenes. Moreover, Bacillus subtilis has shown highly susceptible, which the diameters of inhibition zone values of 28 extracts were between 7 and 14 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) recorded for the different crude ginseng extracts against microorganism using ranged from 6.25 to 100 mg/mL, indicated that the methanol extract of ginseng were more effective than ethanol and water extracts. The 60% methanol extract of red ginseng had the greatest effects against B. subtilis with MIC and MBC values at 6.25 mg/mL.

• Bulletin of the Korean Chemical Society
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• 제14권5호
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• pp.599-602
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• 1993

Micellization process of dodecyltrimethylammonium bromide (DTAB) was studied by using the aromatic probe (benzene) which dissolved in aqueous DTAB solutions. Proton NMR chemical shift measurements of DTAB and DTAB-benzene system showed that benzene molecules solubilized near the micelle-water interface and that the solubilization sites within the micelles are different as the DTAB concentration is passing through 32.0 mM (hereafter we refer this concentration as the second CMC). The change of solubilization sites is also confirmed by abrupt changes of the chemical shifts and relaxation rates of benzene protons in DATB-benzene system at this concentration. It was revealed from the electrical conductivity and viscosity measurements that the solubilization of benzene caused the DTAB micelles to swell out and that the micelles prepared after the second CMC had a greater swelling effect than those prepared before the second CMC. The transition point which reflects the saturation of benzene molecules on the solubilization sites of micelles was observed at one benzene/micellized DTAB mole ratio from the electrical conductivity measurements. Along the different concentration of DTAB solution, this transition point is appeared clearly after the second CMC. From these results it is suggested that the shapes and/or sizes of DTAB micelles of the spherical micelle region prepared after the second CMC are different from those prepared before the second CMC.

• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.283-291
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• 2019

Fermentation of food waste in the presence of different concentrations of salt ($Na^+$) and ammonia was conducted to investigate the interrelation of $Na^+$ and ammonia content in bio-hydrogen production. Analysis of the experimental results showed that peak hydrogen production differed according to the ammonia and $Na^+$ concentration. The peak hydrogen production levels achieved were (97.60, 91.94, and 49.31) ml/g COD at (291.41, 768.75, and 1,037.89) mg-N/L of ammonia and (600, 1,000, and 4,000) $mg-Na^+/L$ of salt concentration, respectively. At peak hydrogen production, the ammonia concentration increased along with increasing salt concentration in the medium. This means that for peak hydrogen production, the C/N ratio decreased with increasing salt content in the medium. The butyrate/acetate (B/A) ratio was higher in proportion to the bio-hydrogen production (r-square: 0.71, p-value: 0.0006). Different concentrations of $Na^+$ and ammonia in the medium also produced diverse microbial communities. Klebsiella sp., Enterobacter sp., and Clostridium sp. were predominant with high bio-hydrogen production, while Lactococcus sp. was found with low bio-hydrogen production.

• Journal of Nutrition and Health
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• 제41권3호
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• pp.242-253
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• 2008

It is a common clinical practice to recommend taking iron supplements for pregnant women during gestation. Although it is required to ensure adequate iron stores during pregnancy, there has been some debate over the interference effects of excessive iron load, because it is possible to compete in the transport in the intestine and placenta and in binding to serum proteins of other trace minerals. In this study, maternal and neonatal serum concentrations of Fe, Zn, Cu, Se, Cr, Mn, and Co were assessed along with maternal Fe intakes. A total of 124 pregnant women and their term neonates participated voluntarily in this research. The women were divided into one of the three groups {high Fe intake (HFI), median Fe intake (MFI), and low Fe intake (LFI)} by their total Fe intakes and one of the two groups (Anemic and Normal) by their Fe nutritional status. All the data were compared among the three groups and between the two groups also. Total Fe intakes of HFI, MFI, and LFI groups were 140.8 ${\pm}$ 76.1, 68.0 ${\pm}$ 11.2, and 30.2 ${\pm}$ 8.6 mg/day, respectively. Those of Anemic and Normal groups were 90.1 ${\pm}$ 74.8 and 86.6 ${\pm}$ 46.8 mg/day, respectively. Maternal Hb concentration and Hct were not significantly different among HFI, MFI, and LFI groups but those were significantly different between Anemic and Normal groups. However, neonatal Hb concentration was not significantly different among HFI, MFI, and LFI groups and between Anemic and Normal groups either. Maternal serum Fe concentrations of the three groups, HFI, MFI, and LFI, were similar but that of Anemic group was significantly lower compared to Normal group. However, there was no significant difference in neonatal serum Fe concentrations among the three groups and between the two groups either. Serum concentrations of the other trace minerals in both mothers and neonates were not significantly different among HFI, MFI, and LFI groups and between Anemic and Normal groups. In addition, in the maternal serum, Fe concentration was positively correlated to Zn and Se concentration, respectively. As for the neonatal serum, Fe concentration showed a positive correlation to Zn, Cu, Mn, Se, and Co concentration, respectively. No trace mineral concentration was found to correlate negatively to Fe concentration in both maternal and neonatal serum, The results in this study indicate that Fe intakes of pregnant women, even if it is considerably above the level of estimated average requirement (EAR), may not affect serum Fe concentration in both mothers and neonates. In addition it might not influence adversely on the availability of other trace minerals including Zn and Cu in both mothers and neonates.

• 한국식품영양학회지
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• 제21권4호
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• pp.485-491
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• 2008

This study investigated the quality characteristics of the white pan breads with garlic powder. Three different powder concentration levels of 1%, 2% and 3% were added to flour to make the breads. The contents of moisture and crude fat of the breads added with garlic powder were lower than that of control group. However, ash content was not significantly different among groups. The pH increased with increasing garlic powder concentration. The weight of breads increased with increasing garlic powder concentration, while the volume and baking loss rate of breads decreased. In color values, with increase of garlic powder concentration, L value decreased, but a and b values increased. The water activity in the breads decreased by increasing garlic powder concentration was the highest in the control group. In the texture analyzer measurement, hardness of the breads increased with increases of garlic powder concentration, but springiness decreased. In the results of sensory evaluation, the quality of the 1% garlic powder breads showed the highest in taste, flavor and overall acceptability. The color, appearance, mouth feel and texture of the breads decreased with the increasing garlic powder content. From the results of this study, the white breads with 2% garlic powder content was shown to have the best quality.

• 한국산업보건학회지
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• 제1권1호
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• pp.68-72
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• 1991

The present investigation studied the welding fumes produced during the arc welding process at a shipyard. The air at the shipyard was sampled (between February and May, 1990) to determine the total welding fume concentration, its heavy metal content and the concentrations of different sized particles of the welding fumes. The results were as follows : 1. Forty-four out of 50 samples showed welding fume concentrations which exceeding the threshold limit value of $5mg/m^3$. The geometric mean of welding fume concentration was $9.73mg/m^3$ ($2.14-24.86mg/m^3$), and the nighest level was found at the dock assembly shop ($12.0mg/m^3$). 2. The welding fume concentration measured with personal air sampler was 4.2 times greater than that measured with area sampler. 3. Of the heavy metals analyzed, Fe was found to be the most concentrated at $1.29mg/m^3$ ; it constitued 13.3% of the total welding fume concentration. 4. Of the different sized particles that make up the welding fumes, there was a tendency for the smaller particles to be more concentrated. Particles that measured $7{\mu}$ or less in diameter constituted 85.8% of the total welding fume concentration.

• 한국양식학회지
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• 제12권3호
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• pp.229-236
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• 1999

in the present study, the zinc toxicity to larval development and seed attachment of the abalone, Haliotis discus hannai was obtained under continuous flow through system. The zinc concentration melted from zinc coating pipe for 7 months ranged from $89.00\pm2.55 \mu\textrm{g}/\ell to 15.23\pm2.58\mu\textrm{g}/\ell(Y=0.85M^2-19.71+109.96)$. Treatments were carried out with zinc concentration $0~160 \mu\textrm{g}/\ell$. The maximum and minimum of fertilization rate were $87.7\pm5.3%$ in control, $83.7\pm7.6%$ in zinc concentration $160\mu\textrm{g}/\ell$, respectively. The maximum and minimum of hatching rate were $87.5\pm4.5%$ in zinc concentration $10\mu\textrm{g}/\ell$, $79.3\pm5.6%$ in zinc concentration $160\mu\textrm{g}/\ell$, respectively. Both of the results were not significantly different (P>0.05). But the normality rate, setting rate and survival rate of abalone larvae at over zinc concentration TEX>$20\mu\textrm{g}/\ell$ decreased rapidly and showed significantly different from those of the other group(P<0.05).