• Journal of Radiation Protection and Research
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• v.9 no.1
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• pp.33-42
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• 1984

A great variety of nuclear gamma rays emitted from fission and activation products of spent nuclear fuel contains much information that can be elicited without affecting the integrity of the fuel elements. But the extraction of such information from the complex spectrum is difficult and requires computer codes. In the present work, a versatile code 'CAERI' was developed which locates peaks and calculates their areas for X-rays as well as gamma rays using elegant features of some widely used programs for gamma-ray peak fitting. 'CAERI' coded in FORTRAN used infinite series approximation more accurate than other workers various, simple, piecewise series approximations for evaluations of the Voigt function which represents the X-ray peak with non-negligible natural line width. 'CAERI' can handle even a complex multiplet consisting of peaks from X-rays and gamma rays in arbitrary mixture, which one often encounters in the isotopic analysis of heavy elements such as U and Pu. The results of the fitting performed on the test spectra of $^{177m}\;Lu\;{\gamma}-ray\;and\;^{235}U\;K_{\alpha}$X-ray show good agreement with those by previous workers.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.618-622
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• 2004

Excitation spectra of the 1.6 rm emission originating from $Ho^{3＋}$：$^{5}$ I$_{5}$ \longrightarrow$^{5}$ I$_{7}$ transition in fluoride, sulfide, and selenide glasses were measured at wavelengths around 900nm where the fluorescing $^{5}$ I$_{5}$ level is located. In specific energy range where the frequency upconversion populating $^{5}$ F$_{1}$ state happens, the excitation efficiency of the 1.6 fm emission was deteriorated in fluoride and sulfide hosts. In selenide however spectral line shapes of the excitation spectrum and the '$^{5}$ I$_{8}$ \longrightarrow$^{5}$ I$_{5}$ absorption spectrum looked seemingly identical to each other. Differences in optical nonlinearity as well as electronic band gap energy of the host glasses used are responsible for the experimental observations. On the other hand, codoping of rare earths such as Tb$^{3+}$, Dy$^{3+}$, Eu$^{3+}$, and Nd$^{3+}$ was effective in decreasint the terminating $^{5}$ I$_{7}$ level lifetime. However, at the same time, some of the codopants increased unnecessary absorption at the 1.6 $\mu$m wavelengths via their ground state absorption. Though the lifetime quenching effect of Eu$^{3+}$ was moderate, it exhibited no additional extrinsic absorption at the 1.6 $\mu$m band.EX>m band.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.101-116
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• 2017

The interaction of U(VI) (hexavalent uranium) species with natural organic matter (NOM) in KURT (KAERI Underground Research Tunnel) groundwater is investigated using a laser spectroscopic technique. The luminescence spectra of the NOM are observed in the ultraviolet and blue wavelength regions by irradiating a laser beam at 266 nm in groundwater. The luminescence spectra of U(VI) species in groundwater containing uranium concentrations of $0.034-0.788mg{\cdot}L^{-1}$ are measured in the green-colored wavelength region. The luminescence characteristics (peak wavelengths and lifetime) of U(VI) in the groundwater agree well with those of $Ca_2UO_2(CO_3)_3(aq)$ in a standard solution prepared in a laboratory. The luminescence intensities of U(VI) in the groundwater are weaker than those of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution at the same uranium concentrations. The luminescence intensities of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution mixed with the groundwater are also weaker than those of $Ca_2UO_2(CO_3)_3(aq)$ in the standard solution at the same uranium concentrations. These results can be ascribed to calcium-U(VI)-carbonate species interacting with NOM and forming non-radiative U(VI) complexes in groundwater.

• Progress in Medical Physics
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• v.12 no.1
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• pp.1-8
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• 2001

Diamond thin films were synthesized by a chemical vapor deposition (CVD). Raman spectrum showed the diamond line at 1332 $cm^{-1}$ / and x-ray diffraction pattern exhibited a strong (111) peak of diamond. The scanning electron microscopy analysis showed that the CVD diamond thin film was grown to be unepitaxial crystallites with pyramidal hillocks. A wavelength-resolved thermoluminescence (TL) of the CVD diamond thin film irradiated with X-rays showed one peak at 430 nm around 560 K. The glow curve of the CVD diamond thin film produced one dominant 560-K peak that was caused by first-order kinetics. Its activation energy and the escape frequency were calculated to be 0.92 ～ 1.05 eV and 1.34 $\times$ 10$^{7}$ sec$^{-1}$ , respectively. The emission spectrum at 560 K was split into 1.63-eV, 2.60-eV, and 3.07-eV emission bands which is known to be attribute to silicon-vacancy center, A center, and H3 center, respectively.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.97-101
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• 2016

ZnO has nanostructured material because of unique properties suitable for various applications. Amongst all chemical and physics methods of synthesis of ZnO nanostructure, the hydrothermal method is attractive for its simplicity and environment friendly condition. Nanostructure ZnO thin films have been successfully synthesized on fluorine doped tin oxide (FTO) substrate using hydrothermal method. A possible growth mechanism of the various nanostructures ZnO is discussed in schematics. The prepared materials were characterized by standard analytical techniques, i.e., X-ray diffraction (XRD) and Field-emission scanning electron microscopy (SEM). The XRD study showed that the obtained ZnO nanostructure thin films are in crystalline nature with hexagonal wurtzite phase. The SEM image shows substrate surface covered with nanostructure ZnO nanrod. The UV-vis absorption spectrum of the synthesized nanostructure ZnO shows a strong excitonic absorption band at 365 nm which indicate formation nanostructure ZnO thin film. Photoluminescence spectra illustrated two emission peaks, with the first one at 424 nm due to the band edge emission of ZnO and the second broad peak centered around 500 nm possibly due to oxygen vacancies in nanostructure ZnO. The Raman measurements peaks observed at $325cm^{-1}$, $418cm^{-1}$, $518cm^{-1}$ and $584cm^{-1}$ indicated that nanostrusture ZnO thin film is high crystalline quality. We trust that nanostructure ZnO material can be effectively will be used as a highly active and stable phtocatalysis application.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.167-167
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• 2013

최근에 산화물 형광체는 황화물 형광체에 비해 높은 화학적 안정성을 나타내기 때문에 백색 발광 다이오드, 전계방출 디스플레이와 플라즈마 디스플레이 패널에 그 응용성을 넓히고 있다. 마그네슘 니오베이트(magnesium niobate, MgNb2O6)는 우수한 유전 특성(상대 유전상수=18.4)을 나타내기 때문에 마이크로파 유전체로 응용 가능하며, 단일상 릴랙서 페라브스카이트(relaxor perovskite) Pb(Mg1/3Nb2/3)O3을 합성하기 위한 전구체 (precursor)로 널리 사용되고 있으며, 나이오븀산염 이온에서 다양한 색상을 방출하는 활성제 이온으로 효율적인 에너지 전달이 일어남으로써 Sm3+, Dy3+, Eu3+와 같은 희토류 이온의 좋은 모체 격자로 개발할 수 있다. 본 연구에서는 마그네슘 니오베이트 MgNb2O6 모체 결정에 다양한 활성제 이온, 즉 Eu3+, Sm3+, Dy3+, Tb3+를 선택적으로 주입하여 발광 효율이 높은 천연색 형광체를 합성하고자 한다. 특히, 모체 결정에 주입되는 활성제 이온 주위의 국소적인 환경이 반전 대칭에서 변형되는 척도를 조사하여 활성제의 주 발광 파장의 세기가 최대가 되는 최적의 조건을 결정하고자 한다. Mg1-1.5xNb2O6:REx3+ 형광체 분말 시료는 초기 물질 MgO, Nb2O5와 희토류 이온을 화학 반응식에 맞게 정밀 저울로 측량하여 플라스틱 용기에 ZrO2 볼과 함께 넣고, 소정의 에탄올을 채운 뒤 밀봉하고서, 300 rpm의 속도로 20시간 볼밀 (ball-mill) 작업을 수행하였다. 그 후, 체(sieve)로 ZrO2 볼을 걸러낸 다음에 혼합된 용액을 각 비커에 담아서 $40^{\circ}C$의 건조기에서 24시간 건조하였고, 건조된 시료를 막자 사발에 넣고 잘게 갈고 80 ${\mu}m$의 체로 걸러낸 후에, 알루미나 도가니에 활성제 이온별로 각각 담아, 전기로에 장입하여 매분당 $5^{\circ}C$의 비율로 온도를 상승시켜 $350^{\circ}C$에서 5시간 동안 하소 공정을 실시한 후에, 온도를 계속 일정한 율로 증가시켜 $1,200^{\circ}C$에서 5시간 동안 소성하여 합성하였다. 합성된 형광체 분말의 결정 구조는 $Cu-K{\alpha}$ 복사선(파장: 1.5406)을 사용하여 X-선회절장치로 측정하였으며, 형광체의 표면 형상은 전계형 주사전자현미경으로 관측하였다. 흡광와 발광스펙트럼은 제논 램프를 광원으로 갖는 형광 광도계를 사용하여 측정하였다. 모체 결정에 활성제 이온 Eu3+, Sm3+, Dy3+, Tb3+가 도핑된 형광체 분말은 각각 적색, 주황색, 황색, 녹색 발광이 관측되었다. 각 발광 스펙트럼과 결정 입자의 크기와 형상 사이의 상호 관계를 조사하였다. 실험 결과로부터, 각 형광체의 발광 파장은 활성제 이온의 종류 와 서로 밀접하게 관련되어 있으며, 형광체 시료 합성시 활성제 이온의 농도를 선택적으로 조절함으로써 발광의 세기를 제어할 수 있음을 확인하였다.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.31-36
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• 2013

The radioactive gas radon ($^{222}Rn$), which is generated from the decay process of uranium ($^{238}U$) originating from the soil of more than 85 percent higher the porosity of the soil, the soil can radiate out the possibility that many isotopes. In order to protect the human body from radon, above all, the development of accurate measurement techniques to formulate appropriate measures should be followed. This study Gamma-ray spectrometry using a high purity germanium (HPGe) detector, if you want to measure radon unstable the nature radiation of the background problems can be reduced, radium and radon daughter nuclides after radioactive equilibrium leads to Radon concentration was measured, the soil samples from the Gamma-ray emitting nuclides, and the energy spectrum is analyzed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.12-17
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• 2007

The effects of the evaporation rate of MgO films using an electron beam on the MgO properties and the discharge characteristics of a plasma display panel(PDP) were investigated and analyzed. Mgo films were deposited with the various MgO evaporation rates. The MgO properties such as the crystal orientation, the surface roughness, and the film structure, were inspected using XRD(X-ray diffractometry), AFM(atomic force microscopy). From the experiments and Paschen law, the maximum value of the secondary, electron emission coefficient $(\gamma)$ was obtained at the evaporation rate of $5\AA/sec$. The minimum firing voltage and the maximum luminous efficiency were obtained at an evaporation rate of $5\AA/sec$. In the MgO film deposited at $5\AA/sec$, the (200) orientation and $F^+$ center were most intensive. The XRD results and cathode-luminescence(CL) spectra show the $\gamma$ values are correlated with $F/F^+$ centers of the molecular structure of MgO films.

• Journal of the Korean Vacuum Society
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• v.22 no.1
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• pp.31-36
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• 2013

For the simplification of doping process in amorphous carbon film, arsenic (As) ions were implanted on the nucleated silicon wafer before the growth process. Then amorphous carbon films were grown at the condition of $CH_4/H_2=5%$ by microwave plasma chemical vapour deposition. Because the implanted seeds were grown at the high temperature and the implanted ions were spread, it was possible to reduce the process steps by leaving out the annealing process. When the implanted amorphous carbon films were electrically characterized in diode configuration, field emission current of $0.1mA/cm^2$ was obtained at the applied electric field of about $2.5V/{\mu}m$. The results show that the implanted As ions were sufficiently doped by the self-annealing process by using the growth after implantation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.389-393
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• 2000

High-quality $Er^{3+}$ doped Mg : $LiNbO_3$single crystal fibers were grown by a micro-pulling down ($\mu$-PD) method. Single crystal fibers were pulled down through the nozzle, at a pulling down rate of 0.5 mm/min and using a Pt crucible with a nozzle 1 mm in diameter in air atmosphere. Defects such as bubbles, cracks and inclusions were not detected in any of the grown crystals. The optical transmission of Er : Mg : $LiNbO_3$crystal was measured and the energy levels of $Er_2O_3$ ion could be calculated. The photoluminescence spectrum of crystal fibers showed an energy band emission with the strongest line corresponding to the $^4I_{3/2}{\to}^4I_{15/2}$transition. The concentration dependence of the entire wavelength region emission intensity upon excitation intensity measured emission intensity for the 3 mol% MgO doped fibers was larger than that for the 1, 5 mol% MgO doped fibers.