• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.400-409
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• 2007

Morphology of methane/propane clathrate hydrate crystal was investigated under different undercooling conditions. After the water pressurized with compound guest gas was fully saturated by agitation, medium within the vessel was rapidly undercooled and maintained at the constant temperature while the visual observations using microscope revealed detailed features of subsequent crystal nucleation, migration, growth and interference occurring within liquid pool. The growth of hydrate was always initiated with film formations at the bounding surface between bulk gas and liquid regions under all tested experimental conditions. Then a number of small crystals ascended, some of which settled beneath the hydrate film. When undercooling was relatively small, some of the settled crystals slowly grew into faceted columns. As the undercooling increased, the downward growth of crystals underneath the hydrate film became dendritic and occurred with greater rate and with finer arm spacing. The shapes of the floating crystals within liquid pool were diverse and included octahedron and triangular or hexagonal platelet. When the undercooling was small, the octahedral crystals were found dominant. As the undercooling increased, the shape of the floating crystals also became dendritic. The detailed growth characteristics of floating crystals are reported focused on the influences caused by undercooling and memory effect.

• Korean Journal of Psychosomatic Medicine
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• v.26 no.2
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• pp.112-118
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• 2018

Objectives : Delirium is one of the most common mental illnesses that can affect cognitive function. Melatonin has been shown to be effective in the treatment of insomnia, and recent studies have shown a protective effect to prevent delirium. This study was conducted to investigate the efficacy of melatonin in delirium patients. Methods : All patients were referred to psychiatric department for insomnia and symptoms of delirium, and were diagnosed delirium by the DSM-5 diagnostic criteria. We compared base line severity of delirium with K-DRS-R-98-R (Korean version of Delirium Rating Scale revised 98) and after taking 2mg of melatonin, retrospectively. The side effects were also identified by referring to the medical records. Results : A total 21 patients had taken melatonin for insomnia and delirious symptoms. The K-DRS-R-98 scores were decreased from $15.24{\pm}2.64$ before treatment to $6.57{\pm}5.42$ after treatment. And CGI-S scores were also decreased from $4.14{\pm}0.48$ before treatment to $2.81{\pm}0.93$ after treatment (p<0.05). Conclusions : This study illustrates the possibility of melatonin as an effective treatment option for delirious symptoms such as disorientation, motor agitation, lability of affect and hallucinations as well as insomnia, with less concerns of drug side effect. Further study with a larger sample and prospective design will be required to confirm these results.

• Food Science of Animal Resources
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• v.24 no.1
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• pp.92-96
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• 2004

pH, Campylobacter spp., Salmonella spp. and Escherichia coli of under-utilized broiler viscera silage added with table sugar during storage at 25$^{\circ}C$ were investigated. pH of silage with 0 and 1 %(w/w) table sugar increased continuously after day 2, but that of 3, 4 and 5% remained 4.0∼4.2 after decrease from 5.2 at day 0. The Campylobacter spp. count of 0% was 8.21 at day 4, however that of 3 and 5% showed 7.56 and 7.38 logCFU/mL, respectively. The Salmonella spp. of 0% maintained 5.8∼6.8 logCFU/mL during fermentation, but that of 3 and 5% was not detected after day 4. The initial E. coli count of silage without table sugar was 5.8 log CFU/mL, but reduced to 4.1 log CFU/mL at day 2, and maintained at the level between 4.0 and 5.0 log CFU/mL, thereafter. However, E. coli was not detected in the silage with 3 and 5% table sugar after day 2. The counts of Campylobacter spp., Salmonella spp. and Escherichia coli of under-utilized broiler viscera silage reduced markedly by adding table sugar. It was proved that the possibility of microbiologically safe broiler offal silage as a potential resource for animal feed materials was improved.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.20-25
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• 1998

To obtain higher yield of 2,3-dihydroxybiphenyl(2,3-DHBP) dioxygenase by recombinant E. coli CK1092 carrying pcbC gene of Pseudomonas sp. P20, the environmental and physiological factors were investigated and the cultural conditions using jar fermentor were studied. E. coli CKl092 was grown in LB medium supplemented with 2% sucrose, as a basal medium. The effect of various metal ions on the enzyme production was investigated. In particular, the enzyme production increased in the presence of $Fe^{3+}$ and $Fe^{2+}$, and showed the maxium at the concentration of $10^{-5}M$. The enzyme production was increased by 55% in the medium containing $Fe^{3+}$ ($10^{-5}M$) ion. The optimal temperature and initial pH for cell growth were $37^{\circ}C$ and 7.0, respectively. In the culture using a fermentor at $37^{\circ}C$, the optimal conditions for the enzyme production were obtained at the initial pH 7.0, 1 v/v/m of aeration rate, 200 rpm of agitation speed. It was found that enzyme activity was higher when cultivated without pH control than with pH control.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.513-519
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• 1999

Chloral hydrate is one of the most widely used sedative agents to control the difficult to treat young age group in the dental clinic. We are often frustrated to see the patient still awake and cry with agitation even after far more than the normal onset time. In such a case, the patient has to be rescheduled for another sedation visit with different agents and/or routes which greatly disappoints the guardians. This case report presents a sedative regimen that can possibly help the clinician complete scheduled treatment without postponement. We have tried sleep induction with Enflurane (1-1.5vol%) for 60 seconds to 37 patients of those who failed to respond properly to the dose(70mg/kg)of oral Chloral hydrate. The average age and weight of the patients was 34.3 months(22-43mo.) and 14.9kg(11-21kg) respectively. It is suggested that sleep induction with low dose Eflurane produced a stable state during dental treatment with respect to vital sign and behavior. Evidence of adverse effect was not detected or reported during and/or after the procedures.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.343-347
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• 1997

Effect of culture conditions on the fermentation of wheat flour solution by mixed lactic acid bacteria of Lactobacillus brevis, L. fermentum and L. plantarum was investigated. The optimum temperature for the fermentation of wheat flour solution was $35^{\circ}C$ because pH decreased the lowest value and TTA (total titrable acidity) increased the highest value at this temperature. In aerobic condition, fermentor was purged with air at 1.0 vvm and was purged with nitrogen gas at 1.0 vvm in anaerobic condition. The decrease of pH and the increase of TTA in aerobic condition were higher than those in anaerobic condition. In aerobic condition, the optimum condition of oxygen supply was found to be oxygen transfer rate coefficient of $60\;hr^{-1}$ which corresponded to agitation speed of 250 rpm in a 5 L fermentor. Repeated fed-batch cultures were performed using pH-stat in order to increase the productivity of fermented wheat flour. With increasing the repeated fraction of culture volume, mean cycle time increased but maximum operation time decreased. However, the volume of produced broth per culture volume per time and total volume of produced broth per culture volume were maximum at the repeated fraction of culture volume of 20%. In a repeated fed-batch fermentation of wheat flour solution using mixed lactic acid bacteria, the culture condition was optimum at temerature of $35^{\circ}C$, aeration rate of 1.0 vvm, oxygen transfer rate coefficient of $60\;hr^{-1}$, and repeated fraction of culture volume of 20%.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.583-590
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• 2012

The HF (Hollow fiber) extraction method was optimized to analysis seven species of pesticides in aqueous sample and analyzing samples by GC/MS. Hollow fiber extraction showed good efficiency when it was conducted under these conditions: organic solvent was toluene and agitation speed was 1200 rpm. The 15% concentration of NaCl was optimized when it was experimented between 5% and 25%. The equilibrium time was determined at 15 minutes. The pH 5 showed the best effect on the extraction efficiency. The linearities of calibration curves of seven species were good with correlation of regression ($r^2$) over 0.995 when they were experimented over a concentration range of $5{\mu}g/L$ to $50{\mu}g/L$. The analytical data exhibited the detection of limits (LODs) range of $0.37{\mu}g/L$ to $1.23{\mu}g/L$ and the limit of quantification (LOQs) range of $1.19{\mu}g/L$ to $3.91{\mu}g/L$. The optimized HF-LPME extraction method provides a simple and effective preparation and requires small amount of organic solvents and samples compared to conventional pre-treatment methods.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.312-317
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• 2002

Erythritol is of interest as a low calorie sweetner. Penicillium sp. KJ8l was screened for erythritol producer in nature. The effect of culture conditions on erythritol production by Penicillium sp. KJ81 was examined. This strain produced about 12 g/l erythritol and a small amout of glycerol. Erythritol was not produced from mannitol, arabinose, sorbitol, and xylose but from glucose, sucrose, fructose, mannose, lactose, maltose, and galactose. This strain was able to produce erythritol in a medium containing 60% sucrose but demonstrated the highest productivity of erythritol in a 30% sucrose medium. The highest yield in Penicillium sp. KJ8l was obtained when 0.5% ammonium sulfate was added to the medium containing 30% sucrose and 0.5% yeast extract. Penicillium sp. KJ81 produced 28.2 g/l erythritol when this strain was cultured in the medium containing 30% sucrose, 0.5% yeast extract, 0.5%$(NH_{4})_{2}SO_{4}$ 0.1% $KH_{2}PO_{4}$ and 0.01% $MgCl_{2}$ under the condition of 1 vvm aeration and 200 rpm agitation at $37^{\circ}C$ for 10 days in 5ι jar fermentor.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.200-207
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• 2009

In this study, the characterization of purified erythritol 4-phosphate dehydrogenase, key enzyme of erythritol biosynthesis, produced by Penicillium sp. KJ81 was investigated. Optimum production conditions of erythritol 4-phosphate dehydrogenase was 1 vvm areration, 200 rpm agitation, at $37^{\circ}C$ for 8 days in the medium containing 30% sucrose, 0.5% yeast extract, 0.5% $(NH_4)_2SO_4$, 0.1% $KH_2PO_4$, and 0.05%$MgCl_2$. Erythritol 4-phosphate dehydrogenase was purified through ultrafiltration and preparative gel electrophoresis from cell extract of Penicillium sp. KJ81. This enzyme was especially active on erythrose 4-phosphate with 1.07 mM of Km value. It gave a single band on native polyacrylamide gel electrophoresis and an isoelectric point of 4.6. The enzyme had an optimal activity at pH 7.0 and $30^{\circ}C$. It was stable between pH 4.0 and 9.0, and also below $30^{\circ}C$. The enzyme activity was completely inhibited by 1mM $Cu^{2+}$ and 1 mM $Zn^{2+}$, but was not significantly affected by other cations tested. This enzyme was inactivated by treatment of tyrosine specific reagent, iodine and tryptophan specific reagent, N-bromosuccinimide. The substrate of the enzyme, erythrose 4-phosphate showed protective effect on the inactivation of the enzyme by both reagents. These results suggest that tryptophan and tyrosine residues are probably located at or near active site of the enzyme.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.670-677
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• 2007

The stability of CGAs(colloidal gas aphrons) prepared from non-ionic and ionic surfactants was investigated. Those surfactants were sodium dodecyl sulfate(SDS), Triton X-100, Tween 80 and Quillaja Saponin. The stability of CGAs prepared from single surfactants or mixed surfactants(two components) using a CGA generate. was investigated as functions of temperature, surfactant concentration and stirring time. Saponin among the single surfactants has shown the longest duration time(143 min) and then, Triton X-100, SDS, and Tween 80 were followed by at room temperature. In case of CGAs heated up to $70^{\circ}C$, SDS endured for 116 min but Saponin lasted for only 105 mit which was a considerable reduction of the duration time of CGAs at room temperature. For mixed surfactant pairs, stability of any one pairs stood between the two. That meant no synergic effect for surfactant blending. At the higher temperature, Saponin+Triton X-100 was disclosed to be the lowest, 53 min meanwhile Saponin+SDS was the highest at ambient temperature. The CGAs, initially about 140 ${\mu}m$ in diameter, began to grow right after the agitation to be about 190 ${\mu}m$ owing to coalescence of the bubbles and then became to collapse. When heated, CGAs including Saponin tended to be smaller while the others to be larger. In summary, we found that the stability of CGAs or the duration time was greater for single surfactants and at room temperature rather than for mixed surfactants that caused substantial intermolecular interactions in the CGA structure and at the higher temperature.