• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.327-331
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• 2012

양전자 소멸 분광법을 이용하여 X선으로 디지털 의료 영상을 회득하는 형광체를 X선 조사에 의한 형광체의 원자 크기 정도 결함의 특성을 조사하였다. 양전자와 전자의 쌍소멸에서 발생하는 511 KeV 감마선 스펙트럼의 수리적 해석 방법인 S-변수를 사용하여 결함의 정도를 측정하였다. 임상에서 X-선을 이용한 디지털 의료영상을 획득할 때 형광체로 사용하고 있는 시료를 사용기간별로 0, 2, 4, 6 구분하여 시료를 실험하였다. 각 시료들에서 측정된 S-변수는 0.4932부터 0.4956 정도의 변화를 보였다. 이에 상응하는 실험 방법으로 같은 시료에 X-선의 에너지와 조사시간 즉 6 MV 및 15 MV의 X-선을 사용하여 3, 6, 9, 그리고 12 Gy의 조사량을 변화시키면서 결함의 정도를 측정 비교하였다. 이 결과 형광체가 시용기간이 길어서 X선에 노출된 횟수가 많을수록 결함의 정도는 증가하는 경향을 보였고 X선의 에너지 강도가 강할수록 결함의 정도가 증가하는 경향을 보였다. 이것은 방사선에 노출된 빈도가 많을수록 영상을 획득하는데 보다 많은 선량이 요구되는 점과 영상의 화질이 저하는 현상을 결함특성 측정을 통하여 규명 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2298-2304
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• 2012

X-ray fluorescence spectrum analysis method can be applied in many areas, including concentration analysis of RoHS elements and heavy metals etc. and we can get analysis results in a relatively short time. Because X-ray fluorescence spectrum has noises and several artifacts that lowers the accuracy of the analysis. This paper analyzes the characteristics of the noise of the X-ray fluorescence spectrum to increase the accuracy of analysis. X-ray fluorescence spectrum have the characteristics of shot noise (Poisson noise), so the noise size is relatively large in the small signal portion and the noise the size is relatively small in the large part of the signal. Existing methods of analysis and to remove noises is a method for general purposes algorithm. Since these algorithm does not reflect these noise characteristics, we get distorted analysis result. We can design efficient noise remove algorithm based on the accurate noise analysis method, and we expect high accuracy results of the elemental concentration analysis result.

• Journal of Radiation Protection and Research
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• v.23 no.1
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• pp.33-47
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• 1998

Using a combination of an X-ray generator Installed in radiation calibration laboratory of Korea Atomic Energy Research Institute (KAERI) and a series of 8 radiators and filters described in ISO-4037, monoenergetic fluorescent X-rays from 8.6 keV to 75 keV were produced. This fluorescent X-rays generated by primary X-rays from radiator were discriminated $K_{\beta}$ lines with the aid of filter material and the only $K_{\alpha}$ X-rays were analyzed with the high purity Ge detector and portable MCA. The air kerma rates were measured with the 35 co ionization chamber and compared with the calculational results, and the beam uniformity and the scattered effects of radiation fields were also measured. The beam purities were more than 90 % for the energy range of 8.6 keV to 75 keV and the air kerma rates were from 1.91 mGy/h (radiator : Au, filter : W) to 54.2 mGy (radiator : Mo, filter : Zr) at 43 cm from center of the radiator. The effective area of beam at the measurement point of air kerma rates was 12 cm ${\times}$ 12 cm and the influence of scattered radiation was less than 3 %. The fluorescent X-rays established in this study could be used for the determination of energy response of the radiation measurement devices and the personal dosemeters in low photon energy regions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.196-196
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• 2012

녹색 형광체 $Ca_{1-1.5x}MoO_4:Tb_x{^{3+}}$ 세라믹 형광체를 고상 반응법을 사용하여 $Tb^{3+}$ 이온의 농도를 변화시키면서 소결 온도 $1050^{\circ}C$와 환원 온도 $950^{\circ}C$에서 각각 5 시간과 2 시간 반응시켜 합성하였다. 형광체의 결정 구조, 여기 및 발광 특성의 변화를 각각 X-선 회절 장치와 광여기 발광 분광기를 사용하여 측정하였다. XRD 결과로부터, 합성된 모든 형광체 분말의 주 피크는 (112)면에서 회절된 신호임을 확인할 수 있었다. 형광 특성의 경우에 여기 스펙트럼은 303 nm를 중심으로 넓은 밴드를 형성하였고, $Tb^{3+}$ 이온의 농도가 증가함에 따라 550 nm에 주 피크를 갖는 녹색 형광 스펙트럼의 세기는 감소하였다.

• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.928-934
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• 1996

Quantitative analysis each portland cement components was conducted by standard calibration method using X-ray fluorescence spectrometer. Standard sample and the unknown sample were prepared by fused cast bead method. In checking the errors of standard cement 227A372 the relative errors of constituents such as CaO, SiO2, Al2O3, Fe2O3, MgO and SrO were less than 1% and the relative errors of constituents such as So3, K2O, TiO2, Na2O P2O5, and Mn2O3 were less than 5% Sample preparation was mainly contributed to the errors. Compared with general wet chemical method the results of X-ray fluorescence analyses were more precise and accurate. Moreover it is possible to analyze precisely a little amount of the constituents such as SrO, Mn2O3 and P2O5 the analyses of which were very difficult using the wet chemical method.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.195-195
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• 2012

$Eu^{3+}$ 이온의 농도비를 변화시키면서 고상 반응법을 사용하여 적색 형광체 $Sr_{1-1.5x}MoO_4:Eu_x{^{3+}}$ 분말을 합성하였다. 제조한 형광체의 결정 구조는 X-선 회절 장치를 사용하여 정방정계임을 확인하였고, 광학 특성은 형광 광도계를 사용하여 상온에서 측정하였다. $Eu^{3+}$ 이온의 농도비가 0.01 mol인 형광체의 경우에, 파장 295 nm로 여기시켰을 때 주된 발광은 파장 619 nm에 최대 세기를 갖는 적색 형광을 나타내었으며, 최대 흡수 스펙트럼은 넓은 밴드를 갖고 파장 302 nm에서 관측되었다.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1308-1314
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• 2018

$Er^{3+}$ and $Yb^{3+}$ co-doped $Y_3Ga_5O_{12}$ polycrystalline powders were prepared by using a solid-state reaction method, and their crystallinities were measured using X-ray diffraction. According to the results of X-ray diffraction, the powders showed a polycrystalline tetragonal structure. The photoluminescence and the upconversion luminescence properties of the $(Y_{0.85-x}Yb_{0.15})_3Ga_5O_{12}:Er^{3+}_x$ (x = 0.03, 0.06, 0.09, 0.12 and 0.15) phosphors were investigated in detail. Green and red upconversion emissions were observed for the phosphors excited by 980 nm radiation from a semiconductor laser. The powders exhibited strong green and weak red upconversion emission peaks at 553 and 660 nm, respectively. Also, their upconversion processes were explained using an energy-diagram analysis and the strongest upconversion intensity was emitted by the powder with a 0.12 mol $Er^{3+}$ ion concentration.

• Analytical Science and Technology
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• v.23 no.1
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• pp.74-82
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• 2010

As a basic research for development of the domestic portable XRF spectrometer, we discussed the analytical results of bench-top and portable XRF methods for RoHS materials of the Cd, Pb, Hg, Cr(IV), polybrominated biphenyls(PBB) and polybrominated diphenyl ehters(PBDE). The instrumental parameters such as measurement time of bench-top and portable XRF were optimized using certified reference materials of polyethylene and polypropylene with 5 hazardous materials of 0~1,200 mg/kg. The quantitative analysis of total-Cr, total-Br, Cd, Hg and Pb in certified reference materials and plastic samples were compared by empirical method, fundamental parameter method of bench-top XRF and portable XRF.

• Cement
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• s.124
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• pp.53-57
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• 1991

• Analytical Science and Technology
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• v.9 no.1
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• pp.20-25
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• 1996

Trace levels of uranium and thorium in geologic samples are determined rapidly by a direct wavelength-dispersive X-ray fluorescence method. Relative intensity of scattered tube radiation was used as an internal standard to compensate for variations in instrumental operating characteristics. U and Th can be determined within a precision of ${\pm}10%$ and accuracy of ${\pm}15%$ or less with measuring times of 50 seconds for Th and 400 seconds for U, respectively. The results of XRF analysis were in good agreement with those of other methods such as nutron activation analysis and inductively coupled plasma atomic emission spectrometry.