• Journal of Hydrogen and New Energy
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• v.8 no.1
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• pp.43-47
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• 1997

A new type of anode materials in form of nanocrystalline composite powders has been developed that offers the potential for dramatically improved discharge capacity and initial activation rate. The composites are synthesized by ball milling of two components - a major component (basic component) having high hydrogen capacity and a minor component (surface activator) with good electrocatalytic activity. The capacity increase observed by ball milling with surface activator. The ball-milled composite materials are easier to activate than the non ball-milled basic component.

• Progress in Medical Physics
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• v.4 no.2
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• pp.37-47
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• 1993

The quality of radiation for a high energy x-ray beam can be specified by its attenuation curve in a selected material. The inverse Laplace transform of the attenuation curve can be used as an approximate indication of the energy spectrum of the beam. We have made a comparative investigation of the estimated spectrum obtained by the Laplace transform analysis of the transmitted exposure data measured in an absorption study of a 6MV x-ray beam. Two of existing transform pair models have been investicated and discussed.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.102-102
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.42-45
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• 2004

High quality CdTe single crystal for the solar cell fabrication was grown by vertical Bridgman method. The etch pits patterns of {111}surfaces of CdTe etched by Nakagawa solution was observed the {111} A composed of Cd atoms with typical triangle etch pits of pyramid mode. From the photoluminescence measurement on {111}A, we observed free exciton($E_x$) existing only higy quality crystal and neytral acceptor bound exciton($A^0$,X) having very strong peak intensity. Then, the full width at half maximum and binding energy of neutral acceptor bound exciton were 7 meV and 5.9 meV, respectively. By Haynes rule, an actibation energy of impurity was 59 meV. Therefore, the origins on impurity level acting as a neutral acceptor were associated Ag or Cu elements.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.338-341
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.588-588
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• 2012

Zn-doped $TiO_2$ mesoporous microspheres with high photocatalytic activity were synthesized via combined sol-gel and solvothermal methods for photocatalytic water splitting. It is found that the photocatalytic water splitting and photocatalytic degradation activity can be enhanced by doping an appropriate amount of Zn. Our results reveal that Zn doping inhibits the recombination of photo-generated charge carriers of $TiO_2$ and improves the probability of photo-generated charge carrier separation and hence the photocatalytic activity of $TiO_2$.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.425-429
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• 2014

Half-metallic nanostructure is highly applicable in the field of Spintronics and electronic device technology. We examine the electronic properties of a ferrocene-based nanowire as a possible candidate for a half-metallic nanostructure using VASP and SIESTA. Ferrocene-based nanowire shows high stability in both binding energy simulation and molecular dynamics (MD) simulation. The density of states (DOS) and the projected DOS of the ferrocene-based nanowire indicate that one-dimensional clustering of ferrocene molecules can be explained because of p-d orbital hybridization between iron and carbon. Half-metallic property and energy dispersion at the Fermi level due to one-dimensional structure is also observed from the DOS results.

• Journal of radiological science and technology
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• v.23 no.1
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• pp.97-101
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• 2000

In this study, the highly sensitive $CaSO_4:Tm$-PTFE TLDs has been fabricated for the purpose of measurement of high energy electron. $CaSO_4:Tm$ phosphor powder was mixed with polytetrafluoroethylene(PTFE) powder and moulded in a disk type(diameter 8.5 mm. thickness $90\;mg/cm^2$) by cold pressing. The absorbed dose distribution and ranges for high energy electron were measured by using the $CaSO_4:Tm$-PTFE TLDs. The ranges determined were $R_{100}=14.5mm$, $R_{50}=24.1mm$ and $R_P=31.8mm$, respectively and the beam flatness, the variation of relative dose in 80% of the field size, was 4.5%. The fabricated $CaSO_4:Tm$-PTFE TLDs nay be utilized in radiation dosimetry for personal, absorbed dose and environmental monitoring.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.199-201
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• 2002

Cancer therapy using high-energy $^{12}$ C ions is successfully under way at HIMAC, Japan. An alternative beam to $^{12}$ C is $^{11}$ C ions. The merit of $^{11}$ C over $^{12}$ C is its capability for monitoring spatial distribution of the irradiated $^{11}$ C by observing the $\beta$$^{+}$ decay with a good position resolution. One of the several problems to be solved before its use for therapy is the amount of nuclear interaction that deteriorates the dose concentration owing to the Bragg curve. Utilizing the dedicated secondary beam course for R&D studies at HIMAC, we measured the total energy loss of $^{11}$ C ions in a scintillator block that simulates the soft tissue in human bodies. In addition to the total absorption $^{11}$ C peak, non-negligible bump-shaped contribution is observed in the energy spectrum. The origin of the bump contribution can be nuclear interaction of the incident $^{11}$ C ions with hydrogen and carbon atoms. Further studies to reduce the ambiguity in dose distribution are mentioned.

• Progress in Medical Physics
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• v.16 no.3
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• pp.155-159
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• 2005

As a part of implantable device in body, a transcutaneous energy transmission system has been developed. It would be desirable to tansfer electrical energy to implantable devices transcutaneously. The distance between transcutaneous transformer windings are approximately equal to the thickness of the human's skin, nominally between 10$\~$20 mm. Class-E resonant amplifier is used to drive a primary coil for high efficiency. Maximum current is above 50 mA at any frequency. The developed system shows that the circuit operates correctly at each frequency; 500 kHz, 1 MHz and 4 MHz.