• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.246-249
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• 2005

The blue-color emitting phosphor powder, $CaMgSi_{2}O_6:Eu^{2+}(CMS:Eu^{2+})$ was synthesized by the solid-state reaction method. The synthesized powder was annealed from room temperature to $1,100^{\circ}C$ in air. Its PL property and valence state of Eu atoms was measured by the photoluminescence (PL) and the electron paramagnetic resonance (EPR) spectrometers, respectively. The PL intensity was stable to $700^{\circ}C$, but drastically decreased to $1,100^{\circ}C$. The behavior of EPR intensity was very similar to the PL intensity. The EPR measurement showed that decreased intensity of the PL was caused to the oxidation from the ion $Eu^{2+}$ to $Eu^{3+}$ ions. The EPR spectrometer was powerful as a tool that could distinguish between the valence states of Eu atom as a dopant in various phosphors.

• Journal of the Korean Chemical Society
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• v.24 no.6
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• pp.421-425
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• 1980

The EPR absorption of furan compounds adsorbed on CuY zeolite was studied. With the adsorption of furan on CuY a new high field having a width of 8 gauss and g-factor of 2.002 appeared in EPR spectrum, while the original signal of Cu(Ⅱ) decreased. When 2-methylfuran was adsorbed on Cu(15)Y a new absorption band with a hyperfine structure appeared. With the increase of the degree of Cu(Ⅱ) ion exchange the resolution of the hyperfine structure became poor. The appearance of the new band was interpreted in terms of the formation of a charge transfer complex between Cu(Ⅱ) ion and the furan ring.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1610-1611
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• 2011

실선로 전력 케이블의 부분방전 측정은 주위 전력설비의 신호들이 혼합되면 정확한 부분방전 진단이 어려운 면이 있다. 본 논문에서는 15kV급 EPR 난연 케이블을 대상으로 거리에 따른 부분방전 신호를 검출 및 감쇄 정도 확인 시험을 통하여 발생 위치 추정 기준을 마련하고자 한다. 이를 위해 길이 500m의 EPR 난연 케이블을 제작하여 모의 선로를 구성하였고, IEC60270에 적합한 Calibrator를 이용하여 신호를 인가한 후 HFCT 센서를 사용하여 일정한 거리를 두고 방전 신호를 검출하고, Techimp사(社)의 PDBASE와 OMICRON사(社)의 MPD600을 이용하여 부분방전 신호를 분류하였다. 전압 인가 지점에서 단계적인 거리증가에 따른 부분방전 신호 감쇄 현상 및 일정 길이(300[m])에 대한 주입 신호별 감도 측정을 분석하였다. 본 논문의 시험대상인 15kV급 EPR 난연 케이블은 원자력 발전소의 배전선으로 사용하기 위해 제작된 것으로, 포설 후 절연체 내에 B/D가 발생했다고 가정했을 때, PD신호의 검출 및 대략적인 위치의 추정은 안전을 최우선시 하는 원자력 발전 및 배전 부문에서 주요한 문제로 부각 될 것이다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.679-685
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• 2008

This paper describes the degraded properties of between the charge and discharge current for ${\gamma}$-ray irradiated in electric power cable rubbers using in nuclear power generating station. The charge and discharge current of degradation in EPR(Ethylene Propylene Rubber), which were irradiated with the radiant capacity of 0.033 Mrad/h, have been measured in order to investigate the influence of the atmosphere(in amount of reinforcing agent, moisture absorption and heat treatment) on electrical properties. When ${\gamma}$-ray were irradiated on the EPR with more reinforcing agent from 4 to 40 Phr, charge and discharge currents was increase due to the amount of reinforcing agent. It was verified that the discharging and charging currents irradiated by ${\gamma}$-ray were higher than those that was not irradiated. The amount of the degraded current was more after moisture absorption than before moisture absorption. The charge and discharge current after heat treatment was similar to that of before heat treatment and it was decreased with the time elapsed. As these properties related with ${\gamma}$-ray irradiation dose, it is suggested that these properties can be utilized as a index of irradiation degradation.

• Journal of Physiology & Pathology in Korean Medicine
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• v.31 no.3
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• pp.167-172
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• 2017

In this study, we investigated the effect of Puerariae Radix ethanol extracts (EPR). The effect of the EPR on proliferation of human hair dermal papilla cells(HHDPCs) by MTT assay and observed Expression of mechanisms that regulate cell proliferation extracellular signal-regulated kinase(ERK) and Akt by western blot. The results showed EPR increased the proliferation of HHDPCs and up-regulation phosphorylation of ERK and Akt. ERK and Akt increased by EPR inhibited phosphorylation by PD98059 (ERK inhibitor) and LY294002 (Akt inhibitor), and cell proliferation was also inhibited. These results suggested EPR increases the proliferation of HHDPCs through phosphorylation of ERK and Akt, and therefore is a beneficial effect for the alopecia treatment.

• Corrosion Science and Technology
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• v.2 no.2
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• pp.59-67
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• 2003

Electrochemical potentiokinetic reactivation (EPR) tests are used to evaluate the degree of sensitization (DOS) of stainless steels and nickel base alloys. The validity of EPR test to detect DOS of these alloys, however, depends all the electrolyte composition employed. The existence of precipitates such as NbC, and TiC, etc. in the alloys also affects the reactivation behaviors of these alloys. In this investigation, the reactions involved during EPR processes are analyzed. In 0.5 M $H_2SO_4$+ 0.01 M KSCN electrolyte, a reactivation peak associated with the localized attack around NbC, different from that of intergranular corrosion, is observed for the solution annealed 347 SS. For solution annealed Alloy 600, matrix corrosion and localized attack around TiC with distinct anodic peaks appeared in the EPR curves are seen in the $H_2SO_4$+ KSCN electrolyte. With proper adjustment of elect rolyte composition, the contribution from intergranular corrosion, as a result of chromium carbide precipitation along the grain boundaries, can be distingui shed from the matrix and localized corrosion for the sensitized Alloy 600.

• Corrosion Science and Technology
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• v.20 no.2
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• pp.77-84
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• 2021

This study aims to optimize the DL-EPR test solution for duplex stainless steel S31083 using the Taguchi design. The test solution parameters applied to the Taguchi design are H₂SO₄, NaCl, KSCN concentration, and temperature. In the experimental design, an orthogonal array of 4 levels 4 factor L₁₆(4⁴) was used. Output values for the orthogonal array were used for resolution (degree of sensitization) and selective etch (I_a) values. The optimal test solution conditions were selected by comparing the normalized S/N ratio for the two reaction properties. As a result, the H₂SO₄ and NaCl were identified as the main factors influencing the sensitivity measurement, but the delta statistics showed that the KSCN concentration and temperature had relatively low influence. The optimal condition was identified as 1.5 M H₂SO₄+0.03 M KSCN+1.5M NaCl at 30 ℃. The degree of sensitization presented a tendency to depend on the heat treatment temperature and time in the optimal test solution. This investigation confirmed the possibility of optimizing the experiment solution for the DL-EPR test of stainless steel using the Taguchi technique.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.551-564
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• 2022

Fragmenting the rock mass is considered as the most important work in open-pit mines. Ground vibration is the most hazardous issue of blasting which can cause critical damage to the surrounding structures. This paper focuses on developing an explicit model to predict the ground vibration through an multi objective evolutionary polynomial regression (MOGA-EPR). To this end, a database including 79 sets of data related to a quarry site in Malaysia were used. In addition, a gene expression programming (GEP) model and several empirical equations were employed to predict ground vibration, and their performances were then compared with the MOGA-EPR model using the mean absolute error (MAE), root mean square error (RMSE), mean (𝜇), standard deviation of the mean (𝜎), coefficient of determination (R²) and a20-index. Comparing the results, it was found that the MOGA-EPR model predicted the ground vibration more precisely than the GEP model and the empirical equations, where the MOGA-EPR scored lower MAE and RMSE, 𝜇 and 𝜎 closer to the optimum value, and higher R² and a20-index. Accordingly, the proposed MOGA-EPR model can be introduced as a useful method to predict ground vibration and has the capacity to be generalized to predict other blasting effects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.132-135
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• 2000

This paper present the results of measured Thermally Stimulated Current of EPR(Ethylene Propylene Rubber) sheet material with variation of bias temperature range of -35~80[$^{\circ}C$], the quality of the material of electrode, condition. The origins of these peaks are that, low temperature peak seems to result from dipole, and high temperature peak from the orientation electronic trap.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.1
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• pp.13-18
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• 2001

Natural alpha radiation produced a stable defect center to certain minerals. Electron Paramagnetic Resonance(EPR) spectroscopy is a powerful tool f3r quantifying this defect center. EPR method has been applied to trace alpha-radiation effect around the uranium ore deposit. The results show that EPR technique can be used to measure rapidly and nondestructively the defect center produced by natural alpha radiation. In general, a good correlation was achieved between defect center concentration and actinide elements(U, Th). These results imply that the concentration of defect center is dependent on the alpha radiation dose over long time scale.