• Journal of radiological science and technology
• /
• v.20 no.1
• /
• pp.65-69
• /
• 1997

[ $Mg_2SiO_4(La.Ho)$ ] thermoluminescent phosphor was made by putting the $MgCl_2.6H_2O$ and $SiO_2$ and by doping the rare earth element of $LaCl_3.7H_2O$ and $HoCl_3$. The heating rate is $10^{\circ}C/sec$ for the thermoluminescent phosphor. Two peaks are found in the measured $Mg_2SiO_4(La.Ho)$ Tl glow curve at $152^{\circ}C$ and $205^{\circ}C$ when the heating rate is $5^{\circ}C/sec$. The peak value at $205^{\circ}C$ is the most sensitive to X-ray among the glow peaks. The activation energy of the main peak has been estimated by the peak shape method. The estimated activation energies for Ho and La are $0.52{\sim}1.77\;eV$ respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.67 no.4
• /
• pp.214-220
• /
• 2018

Light sources induced by gas discharge using rare gases have been widely used in the thin film deposition, the surface modification and the polymer etching. A dielectric barrier discharge (DBD) has been developed in order to consistently emit light and control the wavelength of the emission light. However, much research on the characteristics of the movement of discharge particles is required to improve the efficiency of the light lamp and the life-time of the light apparatus in detail. In this paper, we developed a He DBD discharge simulation tool and investigated the characteristics of discharge particles which were electrons, two positive ions ($He^+$, $He_2^+$) and 5 excited particles ($He^*(1S)$, $He^*(3S)$, $He^*$, $He^{**}$, $He^{***}$). The discharge currents showed the transition from pulse mode to continuous mode with the increase of power. With the accumulated charges on the barrier walls, the discharge current was rapidly increased and caused oscillation of the discharge voltage. As the gas pressure increased, $He_2^+$ and $He^*(3S)$ became the dominant activated particles. The input power was mostly consumed by electrons and $He_2^+$ ion. And the change curve showed that power consumption by electrons increased more with gas pressure than with source voltage or frequency.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.11
• /
• pp.1529-1533
• /
• 2008

The detection characteristics of gamma-irradiated ($0{\sim}10.0\;kGy$) medicinal herbs (Platycodon grandiflorum, Acanthopanax chiisanensis) were investigated by photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR). The results of the PSL, a first screening method in comparison with the TL, showed photon counts greater than 5,000 counts/60 s (positive) in the irradiated samples, while the non-irradiated samples yielded photon counts less than 700 counts/60 s (negative). The TL was also applied for the detection method of irradiated medicinal herbs and showed that the non-irradiated sample revealed a glow curve with a low intensity, while the irradiated samples showed a higher intensity. These results were normalized by re-irradiating the mineral grains with a irradiation dose of 1.0 kGy, and a second glow curve was recorded. The ratio of the intensity of the first glow curve ($TL_1$) to that after the normalization dose ($TL_2$) was determined and compared with the recommended threshold values. TL ratio ($TL_1/TL_2$) was below 0.007 for the non-irradiated sample and higher than 0.1 for all irradiated samples (above 1.0 kGy). ESR spectroscopy revealed specific signals (6.065 mT) derived from free radicals in cellulose containing irradiated medicinal herbs. The P. grandiflorum showed clearer signals than A. chiisanensis. From the results of our studies, the PSL, TL, and ESR determinations were found to be suitable for the detection of irradiated medicinal herbs such as P. grandiflorum and A. chiisanensis.

• Food Science and Preservation
• /
• v.16 no.2
• /
• pp.211-216
• /
• 2009

This study determined the photostimulated luminescence(PSL), thermoluminescence(TL), and electron spin resonance(ESR) properties of wheat and corn irradiated with 0-10 kGy of gamma-ray or electron-beam. PSL values of both irradiated grains, regardless of radiation source, were 241-429 photons/sec in nonirradiated samples(negative values, defined as ${\leq}700$ photons/60 sec) and 5,528-40,870 photons/60 sec in irradiated ones(positive values, defined as ${\geq}5,000$ photons/sec), thereby distinguishing irradiated from nonirradiated samples. The TL glow curves($TL_1$) peaked at around $300^{\circ}C$ in nonirradiated samples, but at about $180^{\circ}C$ in irradiated samples, at high intensities, regardless of radiation source. The TL ratios($TL_1/TL_2$) calculated to strengthen $TL_1$ data reliability were less than 0.03 for nonirradiated samples and over 0.20 for irradiated materials, in good agreement with threshold values for nonirradiated(${\leq}0.1$) and irradiated(${\geq}0.1$) samples. ESR analysis was not applicable in identification of irradiated wheat and corn. Electron-beam irradiation resulted in higher PSL and TL signals than did gamma-rays, at the same applied doses.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.31 no.4
• /
• pp.609-614
• /
• 2002

The characteristics of thermoluminescence (TL) and electron spin resonance (ESR) and organoleptic qualities of gamma-irradiated raisin and dried banana were investigated during storage at 4$^{\circ}C$ for 6 months. The minerals separated from non-irradiated raisins showed TL glow curve (TL$_1$) with very low intensity around 200~30$0^{\circ}C$, while the irradiated samples at 1 kGy or more showed glow curves with higher intensity around 18$0^{\circ}C$, with linear increase by irradiation dose ($R^2$=0.9684), which made it possible to identify irradiated samples during 6 months. Moreover, TL ratios (TL$_1$/TL$_2$) through the reirradiation step at 1 kGy enhanced confidence in the identification of irradiated raisins. The ESR signals of multicomponent lines resulted from crystalline sugar radicals were shown in irradiated banana, identifying irradiated samples. The ESR signal intensity was dependent on irradiation doses ($R^2$=0.8977) and the signals were stable enough to be detected by 6th month after storage. Considering tile marketability of irradiated dried fruits during 6 months at low temperature TL and ESR analyses were shown suitable for the identification of irradiated raisins and dried banana, respectively.

• Analytical Science and Technology
• /
• v.15 no.3
• /
• pp.236-242
• /
• 2002

A method was investigated to determine the thickness of coating on steel sheet using rf glow discharge atomic emission spectrometer. The RF gas-jet boosted glow discharge has such salient feature as good pleasure stability and high sputtering efficiency that it was possible to determine the thickness of silicon resin film on zinc electroplated steel. The erosion speed variation is dependent on discharge power, gas flow rate and discharge pressure. therefore determine discharge condition to measure the thickness of coating on steels. The fundamental studies have been carried out to investigate an optimum condition for in-depth analysis and composition of zinc coating on steel. In this study, the calibration curve for thickness determination of silicon resin film was found to be linear in the range of $1000{\sim}3500mg/m^2$ film thickness. The developed rf gas-jet boosted glow discharge was applied to the analysis of zinc coating and silicon resin film on steel made by RIST.

• Analytical Science and Technology
• /
• v.15 no.6
• /
• pp.514-520
• /
• 2002

The electrothermal vaporization (ETV) hollow cathode glow discharge atomic emission spectrometer for analysis of liquid sample has been developed and characterized. This system has improved the sample introduction method of electrothermal vaporization and the hollow cathode glow discharge. The sample introduction method was possible to provide high analyte transport efficiency to the plasma by helix coil made of tungsten material. In addition, small volume samples (<$30{\mu}{\ell}$) could be used. The system has glow discharge cell with special design for improvement of precision. The effect of discharge parameters such as discharge power, gas flow rate has been studied to find optimum condition. The emitted light was effectively carried into detector by fiber optic cable in UV region. The calibration curve of Pb, Cd were obtained with 3 samples.

• 보존과학연구
• /
• s.26
• /
• pp.189-202
• /
• 2005

This study carried out to understand thermoluminescence dating of ancient tiles at Jinju Janghungri Kilin site. Also radiocarbon dating by the benzene synthesis method and Liquid scintillation counting method were performed for comparison for the agedetermination of charcoal sample at the obtained same site.1st and 2nd glow curve were obtained according to the typical method thermoluminescence. Plateau tests of revealed the proper temperature range to be $300~440^{\circ}C$ Palaeodose average values were formed to the 2.44Gy.Annual dose of ancient tiles was calculated from soil samples and ancient tiles it self by measuring alpha radiation dose, potassium concentrations and water contents respectively. Annual dose average values were calculated to be 7.012mGy/yr.The radiocarbon age(BP year) was converted to calibrated age(AD/BC year) using high precision curve. Radiocarbon ages were calculated to be AD 15~17 .Comparison of samples with their radiocarbon and thermoluminescence ages for revealed the in range the AD 15~17. This result means that the measured absolute ages are in good agreement with each other within the margin of error.

• Journal of radiological science and technology
• /
• v.21 no.2
• /
• pp.47-52
• /
• 1998

Tissue-equivalent $MgB_4O_7$ TL phosphors were prepared and the effects of Lantanides series activators on TLD properties of the phosphors were studied. The glow curve of TLD increased TL intensity and the peak temperature is low that is, the heating rate is $10^{\circ}C/sec$. The activation energy of the main peak estimated by the peak shape method. By these methods, the estimated activation energies were $0.76{\sim}1.55eV$ respectively. The TL phosphors prepared in this work may be utilized to radiation sensor elements because of this high sensitivity to X-ray.

• 전기의세계
• /
• v.27 no.3
• /
• pp.36-42
• /
• 1978

It has been investigates that electric characteristics of plasma electron beam in N$_{2}$, H$_{2}$ and Ar gas jars under various gas pressures during electron beams are formed. The results are as follows: 1)Electron beam is formed in the region of positive resistance on the characteristic curve. This phenomenon is identical in N$_{2}$, H$_{2}$ and Ar gases. 2)But in Ar gas, electron beam is formed at relatively lower gas pressure than in H$_{2}$ and N$_{2}$. 3)In pure gas either N$_{2}$, H$_{2}$ and N$_{2}$ the lower the gas pressure, the higher the voltage drop for the same electron beam current. 4)The region in which electron beam is formed is limited at a given pressure. 5)Beyond the limit mentioned above, it becomes glow discharge state and the current increases radically. 6)At a given gas pressure, electron beam voltage, that is, electrical power input increases with gap length.