• Journal of Information Display
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• v.12 no.3
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• pp.145-152
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• 2011

Since the discovery of fullerenes as a class of nanostructure compounds, many potential applications have been suggested for their unusual structures and properties. The isolated pentagon rule (IPR) states that all pentagonal carbon rings are isolated in the most stable fullerene. Fullerenes $C_n$ are a class of spherical carbon allotrope group with unique properties. Electron transfer between fullerenes and other molecules is thought to involve the transfer of electrons between the molecules surrounding the fullerene cage. One class of electron transfer molecules is the methanofullerene derivatives ([6,6]-phenyl $C_{61}$-butyric acid methyl ester (PCBM), 4-(2-ethylhexyloxy)-[6,6]-phenyl $C_{61}$-butyric acid methyl ester (p-EHO-PCBM), and 4-(2-ethylhexyloxy)-[6,6]-phenyl $C_{61}$-butyric acid (p-EHO-PCBA), 10-12). It has been determined that $C_{60}$ does not obey IPR. Supramolecular complexes 1-9 and 10-12 are shown to possess a previously unreported host.guest interaction for electron transfer processes. The unsaturated, cis-geometry, thiocrown ethers, (1-9) (described as [X-UT-Y], where X and Y indicate the numbers of carbon and sulfur atoms, respectively), are a group of crown ethers that display interesting physiochemical properties in the light of their conformational restriction compared with a corresponding saturated system, as well as the sizes of their cavities. Topological indices have been successfully used to construct mathematical methods that relate structural data to various chemical and physical properties. To establish a good relationship between the structures of 1-9 with 10-12, a new index is introduced, ${\mu}_{cs}$. This index is the ratio of the sum of the number of carbon atoms ($n_c$) and the number of sulfur atoms ($n_s$) to the product of these two numbers for 1-9. In this study, the relationships between this index and oxidation potential ($^{ox}E_1$) of 1-9, as well as the first to third free energies of electron transfer (${\Delta}G_{et(n)}$, for n = 1-3, which is given by the Rehm-Weller equation) between 1-9 and PCBM, p-EHO-PCBM, and p-EHO-PCBA (10-12) as [X-UT-Y]@R(where R is the adduct PCBM, p-EHO-PCBM, and p-EHO-PCBA group) (13-15) supramolecular complexes are presented and investigated.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.3
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• pp.167-173
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• 2011

The Effects of external resistance on electrical properties such as current density, power density and coulombic efficiency were investigated in two-chamber type MFCs using a ferricyanide as reducing agent. A stable electricity was produced when a constant time elapsed after innoculation of mixed cultures into the anode compartment; voltages from 0.13 to 0.16 V was measured at $50{\Omega}$ of external resistance. When the external resistance was increased, the current density decreased and the power density rapidly increased and then slowly decreased. Big variation of electrical properties was observed in high-current density region due to the concentration loss related with substrate consumption in repeated experiments changing the external resistance. The maximum power density ($175.8mW/m^2$) and coulombic efficiency (46.1%) were obtained at $100{\Omega}$ of the external resistance which is nearest with the internal resistance ($134{\Omega}$) of MFC system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.129-135
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• 2017

This study examined the antioxidant activity of the water extract from graviola leaves to develop a harmless and highly stable natural antioxidant. The total polyphenol content, total flavonoid content, DPPH radical scavenging activity, and MTT assay activity were measured. As a result, 62.3 g of the water extract from graviola leaves was obtained at $98^{\circ}C$ using 300 g of graviola leaf powder. The total polyphenol content was $291.97+2.39{\mu}g/mL$ and the total flavnoid content was $161{\pm}7.85{\mu}g/mL$ in a 1 mg/mL water extract from graviola leaves. The DPPH radical scavenging activity showed 51.6%, 67.8%, 79%, 82.4% and 83.9% at concentrations of 1, 2.5, 5, 10 and 15 mg/mL. This shows concentration-dependent scavenging activity and significant antioxidant activity. As a result of measuring the toxicity about HDF cells, a HDF cell survival rate of 100% was observed at a 150 mg /mL concentration, which was the same as that of the control group and a higher cell survival rate at a lower concentration. In conclusion, the graviola leaf extract can be developed as a material of food or cosmetics containing natural antioxidants.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.359-366
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• 2002

Bacillus polyfermenticus SCD which is commonly called as Bisroot strain is being used for functional foods through the treatment of long-term intestinal disorders, since the live strains in the form of active endospores can successfully reach the target intestine in humans. The cells of B. polyfermenticus SCD were treated for 4h in artificial gastric juice (pH 2.0,3.0) and bile acid. Final viability of the strain in artificial gastric Juice (pH 2.0, 3.0) is reached to 62.8% and 81.2% respectively B. polyfermenticus SCD is resistant to antibiotics such as streptomycin, rifampicin, nystatin and ampicilin. B. polyfermenticus SCD is well known supplies the nutrients by synthesizing vitamin $B_1$, $B_2$, C and K. B. polyfermenticus SCD produces various digestive enzymes and the enzymes enable to completely digest diets in our body. Above all, $\alpha$-amylase and pretense activities are very higher than B. subtilis KCTC 1020, about two fold and twenty five fold respectively. B. polyfermenticus SCD is very stable during long-term storage period in phosphate buffers of wide-range pH, solutions of various concentrations of sodium chloride, 5% glucose solution and water.

• Journal of Korean Neurosurgical Society
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• v.61 no.5
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• pp.592-599
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• 2018

Objective : Metastatic brain tumors (MBTs) often present with intracerebral hemorrhage. Although Gamma Knife surgery (GKS) is a valid treatment option for hemorrhagic MBTs, its efficacy is unclear. To achieve oncologic control and reduce radiation toxicity, we used a radiosurgical targeting technique that confines the tumor core within the hematoma when performing GKS in patients with such tumors. We reviewed our experience in this endeavor, focusing on local tumor control and treatment-associated morbidities. Methods : From 2007 to 2014, 13 patients with hemorrhagic MBTs were treated via GKS using our targeting technique. The median marginal dose prescribed was 23 Gy (range, 20-25). GKS was performed approximately 2 weeks after tumor bleeding to allow the patient's condition to stabilize. Results : The primary sites of the MBTs included the liver (n=7), lung (n=2), kidney (n=1), and stomach (n=1); in two cases, the primary tumor was a melanoma. The mean tumor volume was $4.00cm^3$ (range, 0.74-11.0). The mean overall survival duration after GKS was 12.5 months (range, 3-29), and three patients are still alive at the time of the review. The local tumor control rate was 92% (tumor disappearance 23%, tumor regression 46%, and stable disease 23%). There was one (8%) instance of local recurrence, which occurred 11 months after GKS in the solid portion of the tumor. No GKS-related complications were observed. Conclusion : Our experience shows that GKS performed in conjunction with our targeting technique safely and effectively treats hemorrhagic MBTs. The success of this technique may reflect the presence of scattered metastatic tumor cells in the hematoma that do not proliferate owing to the inadequate microenvironment of the hematoma. We suggest that GKS can be a useful treatment option for patients with hemorrhagic MBTs that are not amenable to surgery.

• Food Science and Preservation
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• v.21 no.3
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• pp.442-450
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• 2014

In this study, we isolated a cellulase-producing bacterium isolated from traditional Korean fermented soybean paste and investigated the effect of culture conditions on the production of cellulase. This bacterium, which was identified as Bacillus subtilis 4-1 through 16S rRNA gene sequence analysis, showed the highest cellulase activity when the cells were grown at $45^{\circ}C$ for 24 hours in the CMC medium supplemented with 1.0% of soluble starch and 0.1% yeast extract. The initial optimum pH of the medium was observed in the range of 5.0~9.0. The optimal pH and temperature for the production of cellulase from B. subtilis 4-1 were pH 9.0 and $60^{\circ}C$ respectively. In addition, the enzyme showed significant activity in the temperature range of $20{\sim}90^{\circ}C$, which indicates that B. subtilis 4-1 cellulase is an alkaline-resistance and thermo-stable enzyme. This enzyme showed higher activity with CMC as the substrate for endo-type cellulase than avicel or pNPG as the exo-type substrates for exo-type cellulase and ${\beta}$-glucosidase. These results suggest that the cellulase produced from B. subtilis 4-1 is a complex enzyme rather than a mono-enzyme.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.523-527
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• 2002

LiMn$_2$O$_4$ compounds were synthesized by calcining a mixture of LiOH and MnO$_2$(CMD) at 47$0^{\circ}C$ for 10 h and then calcining again at $650^{\circ}C$ to 90$0^{\circ}C$ fur 48 h in air with intermediate grinding. All the synthesized samples exhibited XRD patterns for the cubic spinel phase with a space group Fd3m. The lattice parameter increased gradually as the sintering temperature rose. The electrochemical cells were charged and discharged fur 20 cycles at a current density 300$\mu$A/$\textrm{cm}^2$ between 3.5 V and 4.3 V. The voltage vs. discharge capacity curves for all the samples showed two plateaus. The LiMn$_2$O$_4$ sample calcined at 90$0^{\circ}C$ had the largest first discharge capacity. This sample exhibited the best crystallinity, had relatively large lattice parameter and had relatively large particles with rectatively homogeneous size. All the samples showed good cycling performances. Among all the samples, the LiMn$_2$O$_4$ calcined at 85$0^{\circ}C$ had relatively large first discharge capacity and very good cycling performance. The addition of excess LiOH and the mixing in ethanol considered to help the formation of the more LiMn$_2$O$_4$ phase per unit weight sample and the more stable LiMn$_2$O$_4$phase. These led to the larger discharge capacities and the better cycling performances. The cyclic voltammograms fur the second cycle of the LiMn$_2$O$_4$ samples showed the oxidation and reduction peaks around 4.05 V and 4.18 V and around 4.08 V and 3.94 V, respectively. The larger first discharge capacity of the sample calcined at the higher temperature is related to the larger lattice parameter.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.41-46
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• 2004

A correlation between fibrinolytic activity and microflora in Korean traditional soybean fermented food was investigated. The fibrinolytic activities of traditional soybean pastes and commercially processed samples were 2.42$\pm$1.01 unit/g and 1.58$\pm$0.98 unit/g, respectively. The cell density of Bacillus in traditional soybean pastes was about 10$^{7}$ CFU/g and its commercially processed one was 10$^{6}$ CFU/g. Acid producing bacteria, fungi and yeast group were higher in commercially processed one. The correlations of fibrinolytic activity and microflora in traditional and commercial Doenjang were positively correlated in Bacillus ($R^2$≒ 0.69), negatively correlated in fungal group ($R^2$≒0.40), and there were no significant correlations in acid forming bacteria and yeast group ($R^2$<0.16). Fibrinolytic activities in Meju and Koji were 6.54$\pm$1.97 unit/g and 1.46$\pm$0.43 unit/g respectively, and were positively correlated with Bacillus. Yeast and acid forming bacteria were grown by 5∼6 decimal induction during fermentation period of Doenjang, but Bacillus, fungal cells and fibrinolytic activity were nearly stable. Results indicate that fibrinolytic activity of Doenjang depends on enzyme induction in Meju or Koji processing by Bacillus, Doenjang fermentation process.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.385-398
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• 2002

To accommodate the increasing number of mobile terminals in the limited radio spectrum, wireless systems have been designed as micro/picocellular architectures for a higher capacity. This reduced coverage area of a cell has caused a higher rate of hand-off events, and the hand-off technology for efficient process becomes a necessity to provide a stable service. Population-based Bandwidth Reservation(PBR) Scheme is proposed to provide prioritized handling for hand-off calls by dynamically adjusting the amount of reserved bandwidth of a cell according to the amount of cellular traffic in its neighboring cells. We analyze the performance of the PBR scheme according to the changes of a fractional parameter, f, which is the ratio of request reservation to the total amount of bandwidth units required for hand-off calls that will occur for the next period. The vague of this parameter, f should be determined based on QoS(Quality of Service) requirement. To meet the requirement the value of Parameter(f) must be able to be adjusted dynamically according to the changing traffic conditions. The best value of f can be determined by a function of the average speed of mobile stations, average call duration, cell size, and so on. This paper considers the average call duration and the cell size according to the speed of mobile stations. Although some difference exists as per speed, in the range of 0.4 $\leq$ f $\leq$ 0.6, Blocking Probability, Dropping Probability and Utilization show the best values.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.313-321
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• 2017

We aimed to develop commercialization process of encapsulation which is superior in productivity compared to existing methods by using sodium alginate. Also, in the same process, sodium alginate with chitosan was used to encapsulate lactic acid bacteria with the same process and then the viable cell counts of the two encapsulated lactic acid bacteria were compared. As a test result of the fluidized drying process developed by the present researchers, it was found that the drying time was shortened by 15 to 20 hours compared to the freeze drying method, but the number of viable lactic acid bacteria was about 75% as compared with freeze drying. However, considering the cost and time of drying, it can be confirmed that the commercialization process is possible by the fluidized bed drying method. When the number of viable cells of Ca-alginate capsule and Chitosan-alginate capsule were compared, it was confirmed that there were about $1{\times}10^9$ or more bacteria in the former and about $1{\times}10^3$ in the latter. The lactic acid bacterium capsules prepared by the present technique were stable for 96 hours or more at pH 4.65 and 6.01, but disappeared within 1 hour at pH 7.07 and 8.35. This suggests that the disintegration of lactic acid bacteria can be easily occurred in small and large intestine.