• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.323-329
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• 1993

In this paper, dependence of the diffraction efficiency upon incident light intensity is studied. The conductivity ratio, which is dependent upon the incident light intensity, changes the static electric field in a crystal. This change of the static electric field modulates the refractive index via linear electro-optic effect. And the change of the refractive index affects the diffraction efficiency. It is found that experimental results with $Fe:LiNbO_3$ crystals are in good agreement with the theory.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.98-104
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• 2005

This study experimentally and theoretically examines the fire characteristics of 100- by 100- by 50-mm samples of flame retardant treated Douglas fir. Samples were exposed to a range of incident heat fluxes 10 to $50kW/m^2$. The time to ignition measurements obtained from the cone heater were used to derive characteristic properties of the materials. A one-dimensional integral model has been used to predict the, time to ignition, critical heat flux and ignition temperature of samples. Ignition data and best-fit curves confirm ${{\dot{q}}_i}^{'}{\rightarrow}{{\dot{q}}_{cr}^{'}\;then\;t_{ig}{\rightarrow}{\infty}$ and when ${{\dot{q}}_i}^'{\gg}{{\dot{q}}_{cr}^'\;then\;t_{ig}{\rightarrow}0$. And Ignition of flame retardant treated samples occurred not at incident heat flux of bellow $10kW/m^2.$. By a one-dimensional integral model, the critical heat flux of each samples was predicted $10.21kW/m^2,\;11.82kW/m^2,\;and\;14.16kW/m^2$ for the D-N, D-F2, and D-F4, respectively. In ignition temperature of each samples, flame retardant treated samples were measured high about $50^{\circ}C$ than non-treated samples. Water-soluble flame retardant used in this study finds out more effect in delay of time to ignition when incident heat flux is low than high.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.323-328
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• 2004

Down-conversion of Eu$^{3+}$ doped LiGdF$_4$ (LGF) for increasing the cell efficiency on dye-sensitized Ti $O_2$ solar cells has been studied. The dye sensitized solar cell (DSC) consisting of mesoporous Ti $O_2$ electrode deposited on transparent substrate, an electrolyte containing I$^{[-10]}$ /I$_3$$^{[-10]}$ redox couple, and Pt counter electrode is a promising alternative to the inorganic solar cell. The structure of DSC is basically a sandwich type, viz., FTO glass/Ru-red dye-absorbed Ti $O_2$/iodine electrolyte/sputtered Pt/FTO glass. The cell without down converter had open circuit potential of approximately 0.66 Volt, the short circuit photocurrent density of 1.632 mA/$\textrm{cm}^2$, and fill factor of about 50 ％ at the excitation wavelength of 550 nm. In addition, 5.6 mW/$\textrm{cm}^2$ incident light intensity beam was used as a light source. From this result, the calculated monochromatic efficiency at the wavelength of 550 nm of this cell was about 9.62 ％. The incident photon to current conversion efficiency (IPCE) of N3 used as a dye in this work is about 80 ％ at around 590 nm and 610 nm, which is the emission spectrum of Eu$^{3+}$ doped LGF, results in efficiency increasing of DSC.C.

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.349-355
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• 2015

Background: The tuberculin skin test (TST) is the standard tool to diagnose latent tuberculosis infection (LTBI) in mass screening. The aim of this study is to find an optimal cut-off point of the TST+ rate within tuberculosis (TB) contacts to predict the active TB development among adolescents in school TB outbreaks. Methods: The Korean National Health Insurance Review and Assessment database was used to identify active TB development in relation to the initial TST (cut-off, 10 mm). The 7,475 contacts in 89 schools were divided into two groups: Incident TB group (43 schools) and no incident TB group (46 schools). LTBI treatment was initiated in 607 of the 1,761 TST+ contacts. The association with active TB progression was examined at different cut-off points of the TST+ rate. Results: The mean duration of follow-up was $3.9{\pm}0.9years$. Thirty-three contacts developed active TB during the 4,504 person-years among the TST+ contacts without LTBI treatment (n=1,154). The average TST+ rate for the incident TB group (n=43) and no incident TB group (n=46) were 31.0% and 15.5%, respectively. The TST+ rate per group was related with TB progression (odds ratio [OR], 1.025; 95% confidence interval [CI], 1.001-1.050; p=0.037). Based on the TST+ rate per group, active TB was best predicted at TST+ ${\geq}$ 16% (OR, 3.11; 95% CI, 1.29-7.51; area under curve, 0.64). Conclusion: Sixteen percent of the TST+ rate per group within the same grade students can be suggested as an optimal cut-off to predict active TB development in middle and high schools TB outbreaks.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.407-413
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• 2005

The optical current transformer was developed for 170 kV GIS using optical fiber. The sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 m. To optimize the optical CT, the output signal was measured according to the setting angle of polarizer and analyzer, The asymmetry and distortion of the output signals were improved when the parallel polarized light was incident to the fiber sensor and under the angle of analyzer was $45^{o}$. The measurement error for the linearity was only $\pm{0.42}\;\%$ to 1,000 A in the case of reflection type.

• 한국해양학회지
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• v.22 no.4
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• pp.271-278
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• 1987

Attempts were made to elucidate the responsible toxin in mussel Mytilus sp. which caused a food pisoning incident in March 1986 in Pusan, Korea. Two persons were dead and 15 persons intoxicated in the incident. The mid-gut glands of the mussel collected were extracted with dichlorlmethane, filtered through a Diaflo ulteafiltration membrane, and then purified by chromatography on Bio-Gel P-2 and Bio-Rex 70. The toxic fractions obtained were analysed by electrophoresis, TLC and ion-pairing reversed phase HPLC analyses. The results showed that the fractions contained GTW$\_$1-4/ as the major component, along with neoSTX, PX$\_$1,2/ as the minor. It was concluded from these results that the causative mussel toxin of the above food poisoning was PSP.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.121-134
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• 1994

Shock tube investigation of ethylene oxide-$0_{2}-N_{2}$ mixture have been performed to reveal detonation characteristics of the mixture in terms of detonation pressure and speed. Theoretical calculation of thermodynamic parameters at the Chapmann-Jouguet detonation of the mixture has been also performed. A comparision of the observed results with the calculated ones can lead us to predict the detonation parameters of ethylene oxide in an artificial air. In addition, we have observed ignition delay times of ethylene oxide mixtures. The best fit of the observed delay times to Arrhenius gas kinetic relation gives : ${\tau}=10^{-144}{e{xp}}(E_a/RT)[C_{2}H_{4}O]^{-4.8}[O_{2}]^{-12.4}[N_{2}]^{-14.1}$ $E_a=3.67kcal/mole$ The observed activation energy is markedly reduced, compared with the case of ethylene oxide diluted in Ar. It could be due to the factor that $N_2$ play a role as detonation promoter yielding very reactive NOx radicals.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.72-76
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• 2019

A Q-switched diode-pumped neodymium-doped yttrium vanadate (YVO₄, λ =1064nm) laser was used for the direct patterning of indium tin oxide (ITO) films on glass substrate. During the laser direct patterning, the laser beam was incident on the two different directions of glass substrate and the laser ablated patterns were compared and analyzed. At a low scanning speed of laser beam, the larger laser etched lines were obtained by laser beam incident in reverse side of glass substrate. On the contrary, at a higher scanning speed, the larger etched pattern sizes were found in case of the beam incidence from front side of glass substrate. Furthermore, it was impossible to find no ablated patterns in some laser beam conditions for the laser beam from reverse side at a much higher scanning speed and repetition rate of laser beam. The laser beam is expected to be transferred and scattered through the glass substrate and the laser beam energy is thought to be also dispersed and much more influenced by the overlapping of each laser beam spot.

• Fire Science and Engineering
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• v.28 no.4
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• pp.97-103
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• 2014

To ensure adequate protection from the risk of burns, fire fighter's turnout has a composite of more than three components and air gaps between layers of materials. During the flame exposure, radiation and convection heat transfer occurs in the air gap, thus the air gap acts as a thermal resistance with non-linear characteristics. Therefore, in this study, the experiments were performed to identify the effect of various air gap width (0~7 mm) on the thermal protective performance of fire fighter's clothing. The temperatures on each layer and RPP (Radiant Protective Performance, the most effective index representing the thermal protective performance) were measured with various incident radiant heat fluxes. The temperature at the rear surface of the garment decreased and RPP increased with increasing air gap width because the thermal resistance increased. Especially, it could be found that RPP value and air gap width has almost linear relation for the constant incident heat flux conditions. Thus relatively simple RPP predictive equation was suggested for various incident heat flux and air gap conditions.

• Journal of radiological science and technology
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• v.42 no.4
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• pp.291-299
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• 2019

The International Electrotechnical Commission (IEC) has regulated the definition and requirements of the exposure index (EI). In this study, we calculated the EI of several image receptors in digital radiography system of two different manufacturers according to the method as per IEC, and evaluated the relationship with incident air kerma. To calculate the EI, w e obtained the characteristics curve of each image receptor by increasing the incident air kerma at RQA 3, 5, 7 and 9, respectively. As a result, there was no significant difference in the EI values between different image receptors of the same manufacturer, but EI values of different manufacturer was different despite the same air kerma was incident. Therefore, understanding the characteristics of the digital radiography systems is important in order to use EI as a tool for measuring and managing the radiation dose.