• Polymer(Korea)
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• v.31 no.1
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• pp.14-19
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• 2007

Demineralized bone particle (DBP) has been used as one of the powerful inducers of bone and cartilage tissue specialization. In this study, we fabricated DBP/PLGA scaffold for tissue engineered disc regeneration. We manufactured dual-structured scaffold to compose inner cylinder and outer doughnut similar to nature disc tissue. The DBP/PLGA scaffold was characterized by porosity, wettability, and water uptake ability. We isolated and cultured nucleus pulposus (NP) and annulus fibrosus (AF) cells from rabbit intervertebral disc. We seeded NP cells into the inner core of the hybrid scaffold and AF cells into the outer portion of it. Cellular viability and proliferation were assayed by 3-(4,5-dimethylthiazole-2-yl) -2,5- diphenyltetrazolium -bromide (MTT) test. PLGA and PLGA/DBP scaffolds were implanted in subcutaneous of athymic nude mouse to observe the formation of disc-like tissue in vivo. And then we observed change of morphology and hematoxylin and eosin (H&E). Formation of disc-like tissue was better DBP/PLGA hybrid scaffold than control. Specially, we confirmed that scaffold impregnated 20 and 40% DBP affected to proliferation of disc cell and formation of disc-like tissue.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.49-57
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• 2003

Approx. 200.000 bpd vacuum residue oil is produced from oil refineries in Korea, and is supplied to use asphalt, high sulfur fuel oil and for upgrading at the residue hydro-desulfurization unit. Vacuum residue oil has high energy content, however its high sulfur content and high concentration of heavy metals represent improper low grade fuel. To meet growing demand for effective utilization of vacuum residue oil from refineries, recently some of the oil refinery industries in Korea, such as SK oil refinery and LG Caltex refinery, have already proceeded feasibility study to construct 435~500 MWe IGCC power plant and hydrogen production facilities. Recently, KIER (Korea Institute of Energy Research) are studying on the Vacuum Residue gasification process using an oxygen-blown entrained-flow gasifier. The experiment runs were evaluated under the reaction temperature: 1.100~l,25$0^{\circ}C$, reaction pressure: 1~6 kg/$\textrm{cm}^2$G, oxygen/V.R ratio: 0.8~0.9 and steam/V.R ratio: 0.4~0.5. Experimental results show the syngas composition (CO+H$_2$): 85~93%, syngas flow rate: 50~l10 Nm$^3$/hr, heating value: 2,300~3,000 k㎈/Nm$^3$, carbon conversion: 65~92, cold gas efficiency: 60~70%. Also equilibrium modeling was used to predict the vacuum residue gasification process and the predicted values were compared reasonably well with experimental data.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.11-17
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• 1999

This experiment was conducted to select and utilize the tolerant rice varieties for ozone stress through comparing the physiological responses. In SOD activity, Backunchalbyeo which treated once by 0.15 ppm $0_3$, Ilpumbyeo and Inbujinado treated twice showed significantly different SOD activity compared with $non-O_3$ treatment. No significant difference of SOD activity in three-times $0_3$ treated Sangnambatbyeo and Hangangchalbyeo was found as compared to ($non-O_3$ treated)control, POD activity, when Sangnammbatbyeo, Hangsngchalbyeo, Ilpumbyeo and Inbujinado were sequently treated by third ozone, showed no significant difference between $O_3$ treatment and $non-O_3$. In the comparison of amino acid content in rice leaf blade between three times $O_3$ treatment and $non-0_3$ treatment in 3 varieties, phenylalanine content represent as increased quantities. Especially, in three times $0_3$ treatment of Sangnambatbyeo, phenylalanine content(O.66 mg/g) was significantly increased as compared with $non-O_3$. Visual-growing characters of Sangnembatbyeo were significantly different between $0_3$ treatment and non-treatment. However, grain-filling rate showed no difference. SOD and POD related to resistant mechanism were high activity. In addition, phenylalanine known as precursor which is synthesized resistant materials was increased by $0_3$ treatment. These results suggested that Sangnambatbyeo which increased SOD and POD activity, and phenylalanine content under ozone stress could be selected as a tolerant variety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.888-894
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• 2015

Inorganic composite particles have excellent physical and chemical characteristics and have been applied in various industries. Recently, many studies have examined the optical properties, such as light scattering, refraction, transmission characteristics, by coating organic-inorganic materials on a substrate, such as mica. Mica is widely applied as a pigment, plastics, painted products, and ceramics because of its high chemical stability, durability and non-toxicity. Magnesium oxide has a range of properties, such as high light transmittance, corrosion resistance and non-toxicity, and it is used as an optical material and polymer additives. To use the optical properties of mica and magnesium oxide, mica was coated with magnesium hydroxide by a dissolution and recrystallization process. In this study, the optimal conditions for the haze value of the particles were found by adjusting the amount of precursors and pH. Magnesium hydroxide layers were formed on the surfaces of mica and converted to MgO after calcination at $400^{\circ}C$ for 4 h. The results showed that the value of MgO-coated mica haze can be controlled easily by the amount of the magnesium hydroxide and pH. The optical properties of the inorganic composite powder were analyzed using a hazemeter and the highest haze value was 85.92 % at pH 9. The physicochemical properties of the synthesized composite was analyzed by SEM, XRD, EDS, and PSA.

• Clinical and Experimental Pediatrics
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• v.52 no.6
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• pp.696-700
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• 2009

Purpose : We screened more than 350 compounds with an endoperoxide ring structure in search of an anti-leukemic drug and found that compound 127 (c-127) could induce significant cytotoxicity in HL-60 cells. In this study, we investigated the molecular mechanisms of compound 127-induced antitumor activity on HL-60 cells. Methods : HL-60 cells were cultured in Rosewell Park Memorial Institute 1640 and cell viability was measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], a tetrazole assay. Apoptosis was assessed by a DNA fragmentation test. Apoptotic machineries were determined by Western blot analysis. Results : C-127 could induce a cytotoxic effect at 24 h and apoptosis at 6 h, which was demonstrated with MTT assay and DNA fragmentation test, respectively. The apoptotic effect of this drug was caused by the activation of the intracellular caspase-8,3 activation, the cleavage of pro-apoptotic Bid, and the increase of c-Jun expression accompanied with JNK (Jun N-terminal kinases) phosphorylation. On the contrary, it increased the expression of anti-apoptotic Bcl-2 levels, leading to the induction of the induction of anti-apoptotic effect. Taken together, the present study demonstrated that c-127 was a potent inducer of cytotoxicity on HL-60 cells through apoptotic mechanisms, which included the activation of caspase family, the regulation of Bcl-2 family, and the activation of JNK signaling pathway. Conclusion : Our results suggest that c-127 has a strong antitumor activity through the regulation of various apoptotic machineries on HL-60 cells. The compound may be utilized as an effective and potentially therapeutic drug in leukemia.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.88-96
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• 2006

Among the various methods for minimization of waste activated sludge, maintaining a low F/M ratio in the bioreactor is known to be the most effective reliable one. In this research, various experiments were performed to check the capability of the nonwoven fabric filter bioreactor, which has been proved able to maintain a low F/M ratio by maintaining a high MLSS concentration, for excess sludge minimization. The reactor was intermittently fed with a synthetic wastewater having a COD concentration of approximately 300 mg/L and no SS. Results of the experiments showed that the F/M ratio in the reactor decreased to a minimum value of 0.02 g COD/g MLSS-day as the MLSS concentration increased to a maximum value of 31,010 mg/L. However, the measured endogenous decay coefficients and oxygen uptake rates of the MLSS confirmed that the activity of the MLSS decreased as the MLSS concentration increased. Based on the increase of MLSS in the reactor and the mass balance during the whole experimental period, the average microorganism yield coefficients were computed to be low values of 0.148 and 0.139 g MLSS/g COD, respectively. These results indicate that the nonwoven fabric filter bioreactor employed in this research is effective for minimization of excess sludge production.

• Analytical Science and Technology
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• v.13 no.3
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• pp.378-384
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• 2000

This Study has been carried out to develop a method of analysis of 8 permitted synthetic food colors [including Brilliant Blue FCF(B1), Indigocarmine (B2), Fast green FCF(G3), Amaranth (R2), Erythrosine (R3), Allura red (R40), Tartrazine (Y4), Sunset Yellow FCF (Y5)] in Korean foods by HPLC. After adjusting to 0.5% HCl, each of the food colors extracted was eluted by Sep-pak $C_{18}$ cartridge. Eluates were then determined by high performance liquid chromatograph with a UV-VIS detector. Recoveries of the 8 synthetic food colors were found to be 81.2-98.0% for soft drinks, 80.6-96.1% for candy, 79.8-96.3% for chewing gum, 76.5-91.7% for cereals, 79.9-93.8% for ice cream and 78.6-94.7% for jelly, respectively. The detection limits were $0.05-0.1{\mu}g/g$.

• Analytical Science and Technology
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• v.13 no.3
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• pp.323-331
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• 2000

Two chelating resins, XAD-16-TAC and XAD-16-TAO were synthesized by Amberlite XAD-16 macroreticular resin with 2-(2-thiazolylazo)-p-cresol (TAC) and 4-(2-thiazolylazo)-orcinol (TAO) as functional groups. The sorption behaviour of Zr(IV), Th(IV) and U(VI) with two chelating resins were examined with respect to the effect of pH and masking agent by batch methods. It was obtained that the optimum pH was in the range of 5-6, and two chelating resins showed good separation efficiency of Zr(IV) or Th(IV) by using $NH_4F$ as a masking agent. Characteristics of desorption were investigated with 0.1-2 M $HNO_3$ as desorption agent. It was found that 2 M $HNO_3$ showed high desorption efficiency to most of metal ions except Zr(IV). XAD-16-TAC resin is applied to separation and preconcentration of trace Zr(IV) from mixed metal ions. Also, Th(IV) ion can be successfully separated from U(VI) and Zr(IV) ion by using XAD-16- TAO resin.

• Analytical Science and Technology
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• v.11 no.5
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• pp.353-359
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• 1998

Danazol, one of the IOC banned substances, is a synthetic steroid which stimulates the synthesis of cellular protein with multiple and diverse biologic effects. To confirm the androgenic effects of danazol, levels of eight endogenous steroids and its major metabolite in human urine were simultaneously analyzed by selected ion monitoring (SIM) of GC/MS after oral administration. The recovery range of this method was 71.59%~93.56% and the RSD values of precision and accuracy test were 1.87%~10.48% and 1.32%~11.25%, respectively. The limits of detection of most of the drugs were $0.01{\sim}0.05{\mu}g/mL$ and calibration was carried out using urine spiked with each endogenous steroid and ethisterone standard at a concentration of 0.1, 0.5, 1.0, 10, 20 and $50{\mu}g/mL$ and with $10{\mu}g/mL$ of internal standard. Correlation coefficients varied between 0.963 and 0.991. The endogenous steroid profiling is one of valuatle tool for decteation of anabolic steroids.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.525-535
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• 2018

If the frequency of a particular class is excessively higher than the frequency of other classes in the classification problem, data imbalance problems occur, which make machine learning distorted. Corporate bankruptcy prediction often suffers from data imbalance problems since the ratio of insolvent companies is generally very low, whereas the ratio of solvent companies is very high. To mitigate these problems, it is required to apply a proper sampling technique. Until now, oversampling techniques which adjust the class distribution of a data set by sampling minor class with replacement have popularly been used. However, they are a risk of overfitting. Under this background, this study proposes ROSE(Random Over Sampling Examples) technique which is proposed by Menardi and Torelli in 2014 for the effective corporate bankruptcy prediction. The ROSE technique creates new learning samples by synthesizing the samples for learning, so it leads to better prediction accuracy of the classifiers while avoiding the risk of overfitting. Specifically, our study proposes to combine the ROSE method with SVM(support vector machine), which is known as the best binary classifier. We applied the proposed method to a real-world bankruptcy prediction case of a Korean major bank, and compared its performance with other sampling techniques. Experimental results showed that ROSE contributed to the improvement of the prediction accuracy of SVM in bankruptcy prediction compared to other techniques, with statistical significance. These results shed a light on the fact that ROSE can be a good alternative for resolving data imbalance problems of the prediction problems in social science area other than bankruptcy prediction.