• Journal of Sensor Science and Technology
• /
• v.2 no.1
• /
• pp.109-115
• /
• 1993

A CdS single crystal was grown by using sublimation method. Lattice constants, $a_{o}$ and $c_{o}$, obtained by using extrapolation were $4.131{\underline{8}}{\AA}$ and $6.712{\underline{2}}{\AA}$, respectively. The carrier density was${\sim}10^{23}m^{-3}$ and the mobility was $2.93{\times}10^{-2}m^{2}$/V sec from measured Hall data at room temperature. The mobility has a increasing tendency in proportion to $T^{1/2}$ from 33 K to 150 K and a decreasing tendency in proportion to $T^{-2}$ from 180 K to room temperature. The short wavelength band peak measured from photocurrent was due to intrinsic transition, and the energy value of this peak was equal to the energy band gap of CdS photoconductor.

• Proceedings of the Korean Aquaculture Society Conference
• /
• 2006.05a
• /
• pp.93-94
• /
• 2006

• The Journal of Natural Sciences
• /
• v.11 no.1
• /
• pp.27-31
• /
• 1999

The Raman scattering was studied from the porous silicons which were made by changing anodization current and time. As the current density was increased, it was observed that Raman peak was red shift and the full width half maximum increased, and was analyzed theoretically.

• Journal of the Korean Chemical Society
• /
• v.42 no.1
• /
• pp.28-35
• /
• 1998

Microorganisms such as alga are able to uptake toxic and heavy metal ions. After Cd(Ⅱ) was preconcentrated on the carbon paste electrode constructed by incorporating alga (Anabaena), it was determined with differential pulse anodic stripping voltammetry. A well-defined oxidation peak of Cd(Ⅱ) was obtained at - 0.75 V vs. SCE. We investigated the optimum conditions using the peak, which are the effect of the amount of alga, pH, ionic strength, temperature, and preconcentration time on the preconcentration of Cd(Ⅱ) and that of the reduction time and potential on the reduction of Cd(Ⅱ) preconcentrated. Calibration curve for the determination of Cd(Ⅱ) was linear over the range of $1.0{\times}10^6\;M\;to\;8.0{\times}10^6$\;M (R=0.9978) and the detection limit was $5.0{\times}10^{-7}$\;M. The relative standard deviation was 3.1% (n=6) for $7.0{\times}10^{-6}\;M Cd(Ⅱ). In regeneration of the electrode surface with 0.1 M HCl, the response was reproducible continuously by 10 times.

• Journal of Radiation Protection and Research
• /
• v.21 no.4
• /
• pp.285-296
• /
• 1996

The energy spectra in the air and water of several ${\gamma}-ray$ sources such as Cr-51, Cs-137, Mn-54, Zn-65 have been investigated using the NaI(T1) scintillation detector. General response functions, which can curve fit the measured spectra, have been constructed. We have found that the constructed response functions can successfully represent the measured spectra in the water as well as in the air, It is possible, by comparing the relevant parameters of the response functions, to quantitatively characterize the changing features of the measured spectra as obtained with varying the water depth. Of the response function parameters, those which affect the shape of the full-energy Peak have most notably changed. Besides, those parameters which affect the shapes of the flat continuum, the Compton continuum and edge have also shown slight changes with varying the water depth.

• Fire Science and Engineering
• /
• v.11 no.1
• /
• pp.3-9
• /
• 1997

The objective of this research is to study on the formations of thermal stratification in a room in case of several furniture fires such as trashcan, carpet, sofa, mattress and wardrobe as a fire starter in a residential room by performing the experimental studies. The uniformly distributed fire in case of carpet showed that the ignition and the initial growth period were relatively short while the fully developed period was considerably long. The concentrated fires such as the mattress and wardrobe showed that the ignitions and the initial growth periods were relatively long. When fire spread to only direction, like the case for the trashcan with a regular shape, there was one peak of temperature profile, and for the irregular shaped furniture such as chair, sofa, mattress and wardrobe, there were two or more peaks. The interface heights for the furniture fires were around 1[m] maintaining constant state. However, at the time of the maximum temperature, the interface height was lowered to 0.25[m]-0.75[m] from the floor.

• Analytical Science and Technology
• /
• v.15 no.5
• /
• pp.393-398
• /
• 2002

A method to determine simultaneously fluorene and anthracene in aqueous solution by synchronous fluorescence spectrometry has been studied. The emission characteristics and optimum wavelength interval (${\Delta}{\lambda}$) for synchronous spectra of fluorene and anthracene in aqueous solution were investigated. The optimum wavelength interval (${\Delta}{\lambda}$) was found to be 50 nm. The calibration curve for fluorene and anthracene in the synthetic mixture solution of both compounds was linear over the range from $5.0{\times}10^{-8}M$ to $1.0{\times}10^{-3}M$ and from $5.0{\times}10^{-8}M$ to $1.0{\times}10^{-3}M$ for fluorene and anthracene, respectively. The detection limit was $3.0{\times}10^{-9}M$ and $7.0{\times}10^{-9}M$, for fluorene and anthracene, respectively under the optimal wavelength interval.

• Journal of the Korean Chemical Society
• /
• v.47 no.2
• /
• pp.137-146
• /
• 2003

3-Hydroxybenzopyran[3,2-c]-[1]-benzopyran-6,7-diones (3) and 3-methoxycarbonylcoumarin (4) were prepared via condensation of 1 with resorcinol in the presence of sodium methoxide. The chemical behavior of 3 towards acetic anhydride, alkyl halides and diazonium chloride is described. The electron impact ionization mass spectra of compounds 4,5 and 6a,b show a weak molecular ion peak and a base peak of m/z 89, m/z 280. m/z 91 and m/z 120 resulting from a cleavage fragmentation respectively. The molecular ion of compounds 3, 6b, and 7a is a base peak of m/z 280, m/z 366 and m/z 488 respectively. Compound 7a give a characteristic fragmentation pattern with a two very stable fragmentation of m/z 383 and m/z 77.

• Journal of the Korean Chemical Society
• /
• v.41 no.8
• /
• pp.385-391
• /
• 1997

Diffusion Coefficient$(D_0)$ and electrode reaction rate Constant$(K_0)$ of Co$(dimethyl bipyridine)_3(ClO_4)_2$ were determined by cyclic voltammetry and chronoamperometry. It was also investigated that the effects of solvent, concentration, and scan rate, etc. on the diffusion coefficient and the temperature effect on the rate constant. The peak currents and diffusion coefficients were dcreased as increasing the viscosity of solvent. Diffusion coefficient was $5.54{\times}10^{-6 }cm^2/sec$ and the reaction rate constant was $2.39{\times}10^{-3 }/s$ at 25$^{\circ}C$. The thermodynamic parameters such as ${\Delta}G^{\neq},\;{\Delta}H^{\neq},\;and\;{\Delta}S$ were calculated from plotting the reaction rate constants versus the solution temperatures. This compound was shown the catalytic effect on the oxygen reduction that the reduction peak current of oxygen was greatly enhanced and the peak potential was shifted to +0.2 volt.

• The Journal of Natural Sciences
• /
• v.7
• /
• pp.37-46
• /
• 1995

Electrochemical behavior of $Ln^{3+},$-ALC complexes($Gd^{3+},$ $Tb^{3+},$ $Dy^{3+},$ $Ho^{3+},$ $Er^{3+},$ $Yb^{3+}$ and $Lu^{3+}$-alizarin complex-one) has been investgated by d.c polarography, differential pulse polarography and cyclic voltammetry. The reduction mechanism of ALC comes to the conclusion that the two electron make one step of reversible processes, and that there is few adsorption in the electrode reaction. The new complex is made from one lanthanide ion and one ALC. This complex is proven to make an adsorptive complex wave, by the experiments of differential pulse polarography and cyclic voltammetry. The reduction potential of complex wave($P_2$)turns up more negatively than ligand wave($P_1$) does. Linear calibration curves of the decreasing P1 and increasing $P_2$ is obtained when the lanthanide concentration varys from $2.5X10^5$M to $1X10^4M$.