• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.432-438
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• 2009

In this paper, we synthesized LSG powder by Modified-GNP method. Lanthanum, strontium and gallium (LSG) were selected in the preparation of an oxygen-electrode (anode) for High Temperature Steam Electrolysis system (HTSE). The used amount and concentration of nitric acid were varied to find out an appropriate composition for oxygen-electrode (anode). In order to optimize the molar ratio of La and Sr, ratio of La to Sr was varied that 2:8, 5:5 and 8:2. The combined LSGs were calcined for 2 hours at $700^{\circ}C$ and were sintered in a furnace for 4 hours at $1200^{\circ}C$. The phase and crystallinity of LSG powder were determined by XRD. The surface morphology was observed through SEM photograph, and the specific surface area was investigated with BET. The thermochemical property was determined by TG/DTA. The synthesized preparation was obtained of $La_{0.8}Sr_{0.2}GaO_{3}$ formula for 3M nitric acid, which was the best perovskite phase.

• Journal of Forest and Environmental Science
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• v.22 no.1
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• pp.13-17
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• 2006

Approximately each 5 kg dried Paulownia coreana leaves, seeds, outer barks, inner barks and wood were ground, extracted with acetone-$H_2O$ (7:3. v/v). concentrated under reduced pressure and successively fractionated using n-hexane. $CH_2Cl_2$, EtOAc and $H_2O$ on a separation funnel. Each fraction was then freeze dried and weighed. The extraction yield of each sample was investigated and the yield of inner barks was the highest, while the wood was the lowest. Antioxidative activities of crude extracts, precipitates and partitioned fractions were evaluated by DPPH radical scavenging method. The results indicated that all EtOAc soluble fractions, including some of $H_2O$ soluble fractions, showed significantly high antioxidative potential compared with ${\alpha}$-tocopherol and BHT used as controls.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.764-769
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• 2001

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutant emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle. Basically, a mixed flow of gas and particle in coal nozzle is required to have appropriate injection and concentration distribution at exit to achieve flame stability and low pollutant, but it is very difficult to obtain that without help of a coal separating device within nozzle. In this study, each distribution of air and coal flow rate is measured for the coal nozzle with coal separator developed by us. The coal concentration at exit is various according to inlet swirl values and positions of coal separator. Also pressure drop is measured for various operating conditions of this nozzle. From these results, we can find the separation characteristic of new developed coal separator, and select proper operation range of coal nozzle. When this coal nozzle is applied to actual plant, these investigations will be very useful to confirm the shape of coal separator to have efficient particle injection.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.49-57
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• 2005

In this paper. a CLB-based CPLD low power technology mapping algorithm for trade-off is proposed. To perform low power technology mapping for CPLD, a given Boolean network has to be represented to DAG. The proposed algorithm consists of three step. In the first step, TD(Transition Density) calculation have to be Performed. Total power consumption is obtained by calculating switching activity of each nodes in a DAG. In the second step, the feasible clusters are generated by considering the following conditions : the number of output. the number of input and the number of OR-terms for CLB within a CPLD. The common node cluster merging method, the node separation method, and the node duplication method are used to produce the feasible clusters. The proposed algorithm is examined by using benchmarks in SIS. In the case that the number of OR-terms is 5, the experiments results show reduction in the power consumption by 30.73$\%$ comparing with that of TEMPLA, and 17.11$\%$ comparing with that of PLAmap respectively

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.574-577
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• 2007

While disk can be overwritten on updating data, because flash memory can not be overwritten on updating data, new data are updated in new area. If data are frequently updated, garbage collection, which is achieved by erasing blocks, should be performed to reclaim new area. Hence, because the number of erase operations is limited due to characteristics of flash memory, every block should be evenly written and erased. However, if data with access locality are processed by cost benefit algorithm with separation of hot block and cold block, though the performance of processing is high, wear-leveling is not even. In this paper, we propose CB-MB (Cost Benefit between Multi Bank) algorithm in which hot data are allocated in one bank and cold data in another bank, and in which role of hot bank and cold bank is exchanged every period. CB-MB showed that its performance was similar to that of others for uniform workload, however, the method provides much better performance than that of others for workload of access locality.

• Journal of Korea Foundry Society
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• v.23 no.3
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• pp.137-146
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• 2003

The main purpose of this study is to investigate the effects of process parameter on alpha-case formation of Ti and TiAl castings. The previous studies showed that the molten titanium is excessively reactive to the refractory oxide mold, resulting in alpha-caes of the titanium castings regardless of composition of titanium alloys. However, the behavior of the alpha-case formation of TiAl alloy is not consistent with conventional titanium alloy. In order to investigate the alpha-case formation of Ti and TiAl castings with process parameter, especially the associated factors of investment mold such as mold material, binder and mold preheating temperature. An attempt has been made to characterize the alpha-case of titanium casting by using optical microscope, EDS, XRD, EMPA and hardness profiles. The formation of the alpha-case on the surface of pure titanium during investment casting was rather by that of solid solution with metallic element from mold material. The required mold strength was obtained with $CaZrO_3$ because of the possibility of using water soluble binder. However, the separation phenomenon between facing and back-up mold materials should be considered. The interfacial reaction of TiAl alloy showed different behavior from that of pure titanium and $Al_2O_3$ was best mold materials. The effect of binder as well as mold material on the formation of alpha-case was significant.

• Parasites, Hosts and Diseases
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• v.48 no.3
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• pp.195-201
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• 2010

We studied on the proteomic characteristics of Toxoplasma gondii KI-1 tachyzoites which were originally isolated from a Korean patient, and compared with those of the well-known virulent RH strain using 2-dimensional electrophoresis (2-DE), mass spectrometry, and quantitative real-time PCR. Two-dimensional separation of the total proteins isolated from KI-1 tachyzoites revealed up to 150 spots, of which 121 were consistent with those of RH tachyzoites. Of the remaining 29 spots, 14 showed greater than 5-fold difference in density between the KI-1 and RH tachyzoites at a pH of 5.0-8.0. Among the 14 spots, 5 from the KI-1 isolate and 7 from the RH strain were identified using MALDI-TOF mass spectrometry and database searches. The spots from the KI-1 tachyzoties were dense granule proteins (GRA 2,3,6, and 7), hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGRPTase), and uracil phosphoribosyltransferase (UPRTase). The spots from the RH strain were surface antigen 1 (SAG 1), L-lactate dehydrogenase (LDH), actin, chorismate synthase, peroximal catalase, hexokinase, bifunctional dihydrofolate reductase-thymidylate synthase (DHTR-TS), and nucleosidetriphosphatases (NTPases). Quantitative real-time PCR supported our mass spectrometric results by showing the elevated expression of the genes encoding GRA 2,3, and 6 and UPRTase in the KI-1 tachyzoites and those encoding GRA 7, SAG 1, NTPase, and chorismate synthase in the RH tachyzoites. These observations demonstrate that the protein compositions of KI-1 and RH tachyzoites are similar but differential protein expression is involved in virulence.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.1
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• pp.46-51
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• 2007

LSM powder material for an oxygen-electrode(anode) of High Temperature Steam Electrolysis (RISE) was synthesized by a Modified-Glycine nitrate process(GNP). Amount of nitric acid and its concentration was varied to find out an appropriate composition for the oxygen-electrode(anode). In order to optimize the amount of Glycine used as an oxidant of self-combustion process, the ratio of Glycine to Anion was varied. $La_{0.8}Sr_{0.2}MnO_3$, $La_{0.5}Sr_{0.5}MnO_3$, and $La_{0.2}Sr_{0.8}MnO_3$ were synthesized in this study. Those LSM were dried for overnight to remove moisture from the material at $110^{\circ}C$ and were calcined 2 hours at $650^{\circ}C$ and were sintered in a furnace for 5 hours at $1400^{\circ}C$. Their structures, surface morphologies, surface areas, and weight changes were investigated with XRD, SEM, BET, and TG/DTA. The best perovskite phase for the oxygen-electrode of HTSE was obtained with $La_{0.8}Sr_{0.2}MnO_3$ formula in which 100 ml of 3M nitric acid was used in the preparation of its formula. The optimized ratio of Glycine to Anion was 2.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.122-128
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• 1994

Macrocyclic ligand has been known to selectively bind with metal ions so that ability applied for the transport of metal ions across the emulsion liquid membrane in this study. The metal ions are transproted from the source phase to the receiving phase by the carrier of the organic phase. Several factors involved in the transport of metal ions acrose the emulsion membrane we reported here and these factors provided the informations for the selective seperation of some metal ion. Stability constants for cation-macrocyclic ligand and metal ion-anion receiving phase interaction are examined as parameters for the prediction of metal ion transport selectivities. $Pb^{2+}$ was transported higher rates than the other metal ions in the mixture solution. The interaction of metal ion to anion in receiving phase is important. $S_2O_3^{2-}$- in replacement of $NO_3^-$ in the receiving phase enhances the transport of $Pb^{2-}$since $Pb^{2-}-S_2O_3^{2-}$interaction is greater than $Pb^{2+}-NO_3^-$ interaction.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.494-500
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• 2014

Indium-doped zinc oxide nanocrystals (IZO NCs), capped with stearic acid (SA) of different sizes, were synthesized using a hot injection method in a noncoordinating solvent 1-octadecene (ODE). The ligand exchange process was employed to modify the surface of IZO NCs by replacing the longer-chain ligand of stearic acid with the shorter-chain ligand of butylamine (BA). It should be noted that the ligand-exchange percentage was observed to be 75%. The change of particle size, morphology, and crystal structures were obtained using a field emission scanning electron microscope (FE-SEM) and X-ray diffraction pattern results. In our study, the 5 nm and 10 nm IZO NCs capped with stearic acid (SA-IZO) were ligand-exchanged with butylamine (BA), and were then spin-coated on a thermal oxide ($SiO_2$) gate insulator to fabricate a thin film transistor (TFT) device. The films were then annealed at various temperatures: $350^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, and $600^{\circ}C$. All samples showed semiconducting behavior and exhibited n-channel TFT. Curing temperature dependent on mobility was observed. Interestingly, mobility decreases with the increasing size of NCs from 5 to 10 nm. Miller-Abrahams hopping formalism was employed to explain the hopping mechanism insight our IZO NC films. By focusing on the effect of size, different curing temperatures, electron coupling, tunneling rate, and inter-NC separation, we found that the decrease in electron mobility for larger NCs was due to smaller electronic coupling.