• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.3106-3111
• /
• 2010

In this study, a comparative study was performed between one- and two-stage refrigeration system to cool the natural gas temperature down to $-40^{\circ}C$ using propane as a chilling medium. As a thermodynamic model, Peng-Robinson equation of state equation was applied and PRO/II with PROVISION release 8.3 at Invensys company was utilized for the simulation of the refrigeration system. Through this study, optimization work showed that two-stage refrigeration system was proven to save about 33.5% refrigeration power consumption compared to the one-stage refrigeration cycle.

• ALGAE
• /
• v.21 no.1
• /
• pp.133-139
• /
• 2006

Outdoor cultivation of cyanobacterium Spirulina platensis was carried out for 40 days in a batch mode. A half concentration of the SOT based on the underground water was used as culture medium. Working volume was 5.7 tons with 0.2 m depth. During cultivation, mean water temperature, DO and light intensity were all in proper conditions for the S. platensis growth. The adjustment of pH to over 10 with Na2CO3 and addition of the 1.5% natural salt were very effective to delete contaminant organisms, Chlamydomonas moewusii and Chlorella minutissima occurred one after the other in the culture. The mean productivity of the biomass based on the dry cell weight from 14 to 25 days, after the contaminants were deleted, was 7.8 g ·m–2· d–1, which was relatively high productivity in that a half concentration of the SOT was used for the culture. Underground water used in the culture minimized contaminants invasion and addition of the 1.5% natural salt was effective to delete contaminants as well as acted as mineral supplement in outdoor cultivation of S. platensis. Harvesting using the floating activity of S. platensis was effective from mass floating in day time after overnight without agitation and illumination.

• BMB Reports
• /
• v.28 no.1
• /
• pp.21-26
• /
• 1995

The Escherichia coli mixed-function serC-aroA operon encodes biosynthethic enzymes for unrelated pathways leading to the syntheses of serine and aromatic amino acids. It has been proposed that the operon is expressed in a cAMP-dependent manner. In this work experiments were performed to investigate the cAMP-dependent expression of the operon. Exogenous cAMP increased ${\beta}$-galactosidase synthesis in the $cya^+$ and cya strains harboring the serC-aroA-lac fusion plasmid. This enhancement was more dramatic in the $cya^-$ strain grown in a minimal medium. In a dot blot assay the serC-aroA mRNA content increased in a concentration-dependent pattern after the addition of exogenous cAMP. The activity of phosphoserine aminotransferase, encoded by the serC gene, apparently increased in E. coli cells after the addition of cAMP. All results obtained confirmed that the expression of the E. coli serC-aroA operon is positively regulated by cAMP at the level of transcription.

• Clinical and Experimental Reproductive Medicine
• /
• v.24 no.1
• /
• pp.27-34
• /
• 1997

This study aimed to evaluate the effect of seminal vesicle fluid (SVF) on the acrosome reaction (AR) occurred spontaneously or induced by $Ca^{2+}$ ionophore A23187, follicular fluid, and progesterone in mouse epididymal sperm. SVF was divided into high (MW>10 kD) and low (MW<10 kD) fractions by ultrafiltration. The low MW fraction of SVF decreased the rate of spontaneous AR, however the high MW fraction did not. It suggested that the low MW fraction of SVF might have contained decapacitation factor(s) responsible for prolonging of time need for capacitation. When sperm preincubated for 60 min in the presence of SVF, the rate of AR induced by A23187 was decreased, but prolongation of preincubation time for 120 min significantly potentiated the AR by A23187. It suggested that addition of SVF into sperm preincubation medium imposed the epididymal sperm a condition similar to ejaculation. AR induced by human follicular fluid or progesterone was also inhibited by SVF. It suggested that substance in SVF might have affected AR of mouse sperm by inhibiting the interaction between AR inducing ligands and sperm surface receptors involved in acrosomal exocytosis.

• The Journal of Natural Sciences
• /
• v.13 no.1
• /
• pp.35-50
• /
• 2003

Granular clay minerals for adsorption of the organic dye prepared a Na-Bentonite and optimum condition calcined temperature $700^{\circ}C$ and polyvinyl alcohol quantity was 25%. Granular clay mineral stable range was pH3 to pH9 and specific area was $83m^2/g$. The adsorption of the organic dye on the Granular clay mineral showed result good adsorption with acid medium and then enthalpy was -3.36 ~ -0.84 kcal/mol. It was exhibit typical physical adsorption.

• The Journal of Natural Sciences
• /
• v.13 no.1
• /
• pp.83-96
• /
• 2003

Effect of Nutrient Concentrations, fertigation frequency, and learching percentage on crop growth and nutrient concentrations in root media were evaluated. The treatment of each irrigation with $50 mg.L^{-1}$ of nitrogen in stage 2 and increase to $80 mg.L^{-1}$ nitrogen in stage 3 had the highest crop growth at 34 days after sowing among treatments tested. Feeding with low nutrient concentrations and elevated frequency decreased crop growth. In treatments of each leaching percentage, feeding with low nutrient concentrations and elevated frequency resulted in increased tissue nutrient contents. The less tissue potassium content and higher calcium and magnesium contents were observed in treatment of 50% leach than those in 0% leach. All treatment tested had soil solution pH higher than 6.8. Electrical conductivity in treatments of 50% leach were lower than those of 0% leach. Feeding with low nutrient concentrations and elevated feeding frequency in each leaching percentage resulted in increased electrical conductivity in soil solution of root media. Trends of medium nutrient concentrations were similar to those of electrical conductivity.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.5
• /
• pp.685-692
• /
• 2012

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

• IMMUNE NETWORK
• /
• v.10 no.6
• /
• pp.230-238
• /
• 2010

Background: The MK1 strain, a novel bacterial isolate from soft-rotten tissue of the Neungee mushroom, produces copious amounts of exopolysaccharide (EPS) in a dextrose minimal medium. This study examined the molecular characteristics and immunomodulatory activity of MK1 EPS. Methods: The EPS in the culture supernatant was purified by cold ethanol precipitation, and characterized by SDS- PAGE/silver staining and Bio-HPLC. The immunomodulatory activities of the EPS were examined using the mouse monocytic cell line, RAW 264.7 cells. Results: The molecular weights of the purified EPS were rather heterogeneous, ranging from 10.6 to 55 kDa. The EPS was composed of glucose, rhamnose, mannose, galactose, and glucosamine at an approximate molar ratio of 1.00 : 0.8 : 0.71 : 0.29 : 0.21. EPS activated the RAW cells to produce cytokines, such as TNF-${\alpha}$ and IL-$1{\beta}$, and nitric oxide (NO). EPS also induced the expression of co-stimulatory molecules, such as B7-1, B7-2 and ICAM-1, and increased the phagocytic activity. The macrophage-activating activity of EPS was not due to endotoxin contamination because the treatment of EPS with polymyin B did not reduce the macrophage-activating activity. Conclusion: The EPS produced from the MK1 strain exerts macrophage-activating activity.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.4
• /
• pp.148-156
• /
• 2001

Brake judder, one of low Sequency vibrations in brake system is determined by the excitation of Brake Torque Variation (BTV). The largest contributor to BTV is disc thickness variation. In this study, the static loads of brake torque at Suspension Mounting Points (SW) are obtained by the quasi-static analysis using DADS. The dynamic loads with frequency of BTV at SW are derived from correlation between forced vibration analysis with static loads and brake test results. And the accelerations at steering wheel were analyzed by forced vibration analysis with dynamic loads using commercial finite element program MSC/NASTRAN so that vibration characteristics of vehicle due to brake judder were investigated. Reliability of analysis results was verified through comparing the brake test results. Also, a parametric study with natural frequencies of frame, such as the 1st torsional mode and 1st bending mode, was conducted to reduce vibration amplitudes. As a result we could detect frame natural frequency conditions to improve vibration characteristics and obtained the frame model to reduce vibration amplitude.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.3
• /
• pp.48-56
• /
• 2000

Yellow dye-stuffs in natural plant were extracted from a gardenia, saffron, safflower, amur tree and pagoda. And then they were used to color Korean handmade paper(Hanji) on using a mordant. The results of the degree of discoloration are as follows. 1. As for a gardenia(Gardenia jasminodes Ellis for. grandiflora Makino), the effects of coloring were outstanding in the acid area. But for the preservation, it might be desirable that used a lye in a dye-stuff obtained at $40{\pm}5^{\circ}C$. 2. As for saffron(Curcuma longa L.), when used alum as a mordant, it was colored to a medium yellow color with green color. But easily discolorated and was not desirable. And, it didn't fit in a dye-stuff of Hanji. 3. For safflower(Carthamus tinctorius L.), when pH was in the low acid it was colored to the cleaner yellow color. It was the distinction of discoloration that the degree of brightness's increase was low. 4. For amur cork-tree(Phellodendron amurense Rupr.), the effects of yellow coloring were great in the areas of acidity and alkali. But, when used alum, the degree of the discoloration was high and was not effective. 5. For pagoda tree(Styphnolobium Japonica L.), using a calcium hydroxide as a mordant, enabled the more than average yellow to be gained. The degree of discoloration was good.