• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.3
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• pp.116-120
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• 2015

$La_2NiO_{4+{\delta}}$ based oxides, a mixed electronic-ionic conductors (MIECs) with $K_2NiF_4$ type structure, have been considerably investigated in recent decades as electrode materials for advanced solid oxide fuel cells (SOFCs) due to their high electrical conductivity, and oxidation reduction reaction (ORR). In this study, structure properties of $La(Ca)_2Ni(Cu)O_{4+{\delta}}$ were studied as a potential cathode for intermediate temperature SOFCs (IT-SOFCs).

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.173-178
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• 1994

The water-based magnetic fluids were prepared with the synthesized ultra-fine magnetite, oleic acid and SDBS (sodium dodecyl benzene sulfonate) as surfactants. The dispersion of water-based magnetic fluids was about 90 % when the added amounts of oleic acid and SDBS for magnetite(27 g) were more than $2.66{\times}10^{-3}$ mol and 10 g respectively. As the solid content increased from o. 05 g/cc to 0.4 g/cc, saturation magnetization of magnetic fluids at 5 kOe increased from 1.98 emu/g to 9.63 emu/g at $Fe^{2+}/Fe^{3+}=0.5$ and from 2.7 emu/g to 14.63 emu/g at $Fe^{2+}/Fe^{3+}=1.0$, and the its viscosity increased from 1.3 cp to 4.4 cp at $Fe^{2+}/Fe^{3+}=0.5$. pH region of oleic acid and SDBS stabilized water-based mag¬netic fluids was stable was in the range of pH 3.0 to pH 11.0. Stability of Water-based magnetic fluids can be obtained by observation of magnetic memory patterns on the VCR tape.

• Fire Science and Engineering
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• v.22 no.2
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• pp.63-69
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• 2008

The characteristics of the spread of a forest fire are generally related to the attributes of combustibles, geographical features, and meteorological conditions, such as wind conditions. The most common methodology used to create a prediction model for the spread of forest fires, based on the numerical analysis of the development stages of a forest fire, is an analysis of heat energy transmission by the stage of heat transmission. When a forest fire breaks out, the analysis of the transmission velocity of heat energy is quantifiable by the spread velocity of flame movement through a physical and chemical analysis at every stage of the fire development from flame production and heat transmission to its termination. In this study, the formula used for the 1-D surface forest fire behavior prediction model, derived from a numerical analysis of the surface flame spread rate of solid combustibles, is introduced. The formula for the 1-D surface forest fire behavior prediction model is the estimated equation of the flame spread velocity, depending on the condition of wind velocity on the ground. Experimental and theoretical equations on flame duration, flame height, flame temperature, ignition temperature of surface fuels, etc., has been applied to the device of this formula. As a result of a comparison between the ROS(rate of spread) from this formula and ROSs from various equations of other models or experimental values, a trend suggesting an increasing curved line of the exponent function under 3m/s or less wind velocity condition was identified. As a result of a comparison between experimental values and numerically analyzed values for fallen pine tree leaves, the flame spread velocity reveals a prediction of an approximately 10% upward tendency under wind velocity conditions of 1 to 2m/s, and of an approximately 20% downward tendency under those of 3m/s.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.456-461
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• 2005

This study was carried out to induce plant regeneration via shoot formation from sucker explants of Rubus fruticosus L. To induce adventitious shoots, sucker explants were sterilized in $1.2\%$ NaOCl solution, and cultured on the MS solid medium supplemented with kinetin (0.5, 1.0, 3.0 mg/L) and BA (0.5, 1.0, 3.0 mg/L), respectively. As above, to induce adventitious shoots, sucker explants were cultured on the MS solid medium supplemented with IBA (0, 0.1, 1.0 mg/L) and BA (0, 0.1, 1.0, 2.0 mg/L). After 4 weeks of culture, the highest frquency $(100\%)$ of shoot formation from sucker explants was obtained from the medium with 1.0 mg/L BA. The highest shoot number per explant from in vitro shoot explants was 5.3. After 10 weeks of culture, the number of shoot per explant was increased. The highest frequency $(85\%)$ of root formation was obtained at 0.5 mg/L glycine medium, when the explant with shoot were cultured on the MS medium containing glycine at various concentrations from 0 to 2.0 mg/L. The survival rate of the plantlets after transfer to plastic pots containing sand, soil, and vermiculite (1:1:1, vol.) was $95\%$. The results indicate that micropropagation procedure can be applied for an efficient mass propagation of Rubus fruticosus.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.563-574
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• 2007

Laser induced breakdown spectroscopy (LIBS) is a recently developed analytical technique that is based upon the measurement of emission lines generated by atomic species close to the surface of the sample, thus allowing their chemical detection, identification and quantification. With powerful advantages of LIBS compared to the conventional analytical methodology, this technique can be applied in the detection of heavy metals in the field. LIBS allows the rapid analysis by avoiding laborious chemical steps. LES have already been applied for the determination of element concentration in a wide range of materials in the solid, liquid and gaseous phase with simplicity of the instrument and diversity of the analytical application. These feasibility of rapid multi elemental analysis are appealing proprieties for the in-situ analytical technique in geochemical investigation, exploration and environmental analysis. There remain still some limitations to be solved for LIBS to be applied in soil environment as an in-situ analytical technology. We would like to provide the basic principle related to the plasma formation and laser-induced breakdown of sample materials. In addition, the matrix effect, laser properties and the various factors affecting on the analytical signal of LIBS was dealt with to enhance understanding of LIBS through literature review. Ultimately, it was investigated the feasibility of LIBS application in soil environment monitoring by considering the basic idea to enhance the data quality of LIBS including the calibration method for the various effects on the analytical signal of LIBS.

• KSBB Journal
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• v.18 no.3
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• pp.190-196
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• 2003

An analytical system detecting DNA particularly utilizing a concept of membrane strip chromatography initially applied to home-version tests for, such as, pregnancy and ovulation has been developed. We have chosen S. typhimurium as model analyte among food-contaminating microorganisms that occurred in high frequencies, and invA gene, as a detection target, specific to Salmonella species. This gene was able to be amplified by PCR under optimal conditions employing newly designed primers in our laboratory. The PCR product was specifically measured via hybridization between the analyte and a DNA probe, which was a totally different feature from the conventional gel electrophoresis detecting the products based only on the molecular size. It is notable thar the DNA probe sequence was specially designed such that no separation of excess primers present after PCR was required. This was immobilized on a nitrocellulose (NC) membrane via streptavidin-biotin linkage minimizing a steric effect when the hybridization with the amplified DNA took place. The analyrical system detected the microorganism in a concentration of minimum $10^3$ cfu/mL (i.e., 10 cells per system), estimated from the standard curve, 20 to 40 minutes after adding the sample. This sneitivity was approximately 10 times higher than that of gel electrophoresis as an analytical tool conventionally used. Furthermore, the assay was able to be run at room temperature, which would ofter an extra advantage to users.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.704-711
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• 2010

Lignocellulose ($2^{nd}$ generation) is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of agriculture residuals and nonedible crops biomass, e.q., rice straw and miscanthus sinensis, because of their several superior aspects as agriculture residual and nonedible crops biomass; low lignin, high contents of carbohydrates. In this article, as the basic study of AP(Ammonia Percolation), the properties and the optium conditions of process were established, and then the overall efficiency of AP was investigated. The important independent variables for AP process were selected as ammonia concentration, reaction temperature, and reaction time. The percolation condition for maximizing the content of cellulose, the enzymatic digestibility, and the lignin removal was optimized using RSM(Response Surface Methodology). The determined optimum condition is ammonia concentration; 11.27%, reaction temperature; $157.75^{\circ}C$, and reaction time; 10.01 min. The satisfying results were obtained under this optimized condition, that is, the results are as follows: cellulose content(relative); 39.98%, lignin content(relative); 8.01%, and enzymatic digestibility; 85.89%.

• Progress in Medical Physics
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• v.14 no.2
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• pp.74-80
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• 2003

The purpose of this study was to evaluate the performance of the teflon encapsulated TLD rod, which may be used in nuclear medicine for the direct in vivo measurements of radiation dose. We analyzed the influence of teflon encapsulation for measuring absorbed dose. An experiment was carried out to evaluate and observe the response of a LiF TLD-100 rod in a thin-wall teflon capsule at different depths in a solid phantom. An adult anthropomorphic phantom was used to measure the absorbed dose using thin teflon encapsulated TLD. The measurements of PDD-, and TMR in solid phantom and athe bsorbed dose in humanoid phantom performed with normal TLD were compared with values obtained by teflon encapsulated TLD. It was demonstrated that the difference of TL response of LiF in phantom with and without teflon thin-wall capsule was less than 3％ under the same conditions beyond the build-up region. However, significant differences were observed near the phantom surface because of the build-up effect caused by the thin-wall thickness of the teflon capsule. Thus, our study showed that the contribution of teflon thin-wall capsule to TLD response for the megavoltage photon beams was negligible and that it did not significantly effect dose measurement. The teflon encapsulated TLD described in this work has been proven to be appropriate for in vivo dosimetry in therapeutic environments.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1075-1082
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• 1999

Composite air electrodes of 50/50 vol% LSM- YSZ where LSM =$\textrm{La}_{1-x}\textrm{Sr}_{x}\textrm{MnO}_{3}$(0$\leq$x$\leq$0.5) were prepared by colloidal deposition technique. The electrodes were then examined by scanning electron microscopy (SEM) and studied by ac impedance spectroscopy in order to improve the performance of a solid oxide fuel cell (SOFC). Reproducible impedance spectra were confirmed by using the improved cell, consisting of LSM- YSZ/YSZ/LSM-YSZ. These spectra were a strong function of operating temperature and the stable conditions for the cells were typically reached at $900^{\circ}C$. The typical spectra measured for an air//air cell at $900^{\circ}C$ were composed of two arcs. Addition of YSZ to the LSM electrode led to a pronounced decrease in cathodic resistivity of LSM-YSZ composite electrodes. Polishing the electrolyte surface to eliminate the influences of surface impurities could further reduce cathode resistivity. The cathodic resistivity of the LSM-YSZ electrodes with catalytic interlayer (Ni or Sr) was much smaller than that of LSM-YSZ electrodes without catalytic interlayer. In addition, the cathodic resistivity of the LSM-YSZ electrodes was a strong function of composition of electrode materials, the electrolyte geometry, and applied current.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.339-344
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• 2001

An all solid-state thin film supercapacitor (TFSC) with Co$_3$O$_4$/LiPON/Co$_3$O$_4$ structure was fabricated on Pt/Ti/Si substrate using Co$_3$O$_4$ thin film electrode. Each Co$_3$O$_4$ film was grown by reactive dc reactive magnetron sputtering with increasing $O_2$/[Ar+O$_2$] ratio. Amorphous LiPON electrolyte film was deposited on Co$_3$O$_4$/Pt/Ti/Si in pure nitrogen ambient by using reactive rf magnetron sputtering. The electrochemical behavior of the Co$_3$O$_4$/LiPON/Co$_3$O$_4$ multi-layer structures exhibits a behavior of a bulk-type supercapacitor, even though much lower capacity (from 5 to 25 mF/$\textrm{cm}^2$-$\mu\textrm{m}$) than that of the bulk one. It was found that the TFSC showed a fairly constant discharge capacity with a constant current of 50 $\mu\textrm{A}/\textrm{cm}^2$ at the cut-off voltage 0-2V during 400 cycles. It is shown that the electrochemical behavior of the Co$_3$O$_4$/LiPON/Co$_3$O$_4$ TFSC is dependent upon the sputtering gas ratio. The capacity dependency of electrode films on different gas ratios was explained by different structural, electrical, and surfacical properties.