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이재범,김선태,Lee, Jae-Bum,Kim, Seon-Tai 한국재료학회 2006 한국재료학회지 Vol.16 No.12
In this study, we report a method to synthesize the aluminum nitride (AlN) powders from aluminum oxyhydroxide (AlOOH). AlOOH powders were prepared from the aluminum hydroxide ($Al(OH)_3$) by heattreatment at the reaction temperature of $350^{\circ}C$. Simple heat treatment of AlOOH in the flow of $NH_3$ gas leads to the formation of hexagonal AlN powders through intermediate conversion of ${\delta}-,\;{\gamma}-$ and ${\alpha}-Al_2O_3$. The FTIR transmission spectra show a broad peak related to Al-N bonds centered around 690 $cm^{-1}$ confirming the presence of AlN. The major peaks in Raman spectra were observed in 250 $cm^{-1}$ and 659 $cm^{-1}$. From the results, synthesized powders from the AlOOH powders were confirmed AlN powders.
Vapor Transport Epitaxy에 의한 GaN의 성장과 특성
이재범,김선태,Lee, Jae-Bum,Kim, Seon-Tai 한국재료학회 2006 한국재료학회지 Vol.16 No.8
Highly c-axis oriented poly-crystalline GaN with a dimension of $1{\sim}3\;{\mu}m$ was deposited on $c-Al_2O_3$ substrate by vapor transport epitaxy (VTE) method at the temperature range of $900{\sim}1150^{\circ}C$. XRD intensities from (00'2) plane of grown GaNs were increased with reaction conditions which indicate the improvement of the crystal quality. In the PL spectra measured at 10 K, the spectrum composed with the neutral-donor bound exciton-related emission at 3.47 eV, crystal defect-related emission band at 3.42 eV and with its phonon replicas. The fact that intensity of $I_2$ were increased and FWHM were decreased with growth conditions means that the quality of GaN crystals were improved. With this simple VTE technology, we confirm that the GaNs were simply deposited on sapphire substrate and crystal quality related to optical properties of GaN grown by VTE were relatively good. PL emission without deep level emission in spite of polycrystalline structure can be applicable to the fabrication of large area and low cost optical devices using poly-GaN grown by VTE.
GaOOH 선구체의 스핀코팅에 의한 GaN 박막의 성장
이재범,김선태,Lee, Jae-Bum,Kim, Seon-Tai 한국재료학회 2007 한국재료학회지 Vol.17 No.1
GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.
ZVS Center-Tapped Half-Bridge Zeta Converter with Reduced Output Filter Inductor Size
Jae-Bum Lee(이재범),Ki-Bum Park(박기범),Hyoung-Suk Kim(김형석),Hyun-Wook Seong(성현욱),Gun-Woo Moon(문건우) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
In this paper, a new half-bridge zeta converter employing a center-tapped rectifier is proposed. The proposed converter provides a bidirectional powering path in the rectifier. As a result, its improved rectifier voltage waveform reduces the output filter inductor size. Also, it maintains a wide ZVS range due to the characteristic of the conventional single-ended half-bridge zeta converter. The operational principles, the theoretical analysis, and the design considerations of the proposed converter are analyzed. To verify the performance of the proposed converter, experimental results from a 180W prototype are presented.
이재범(Jae Bum Lee),김용국(Yong Kuk Kim) 한국사회체육학회 2010 한국사회체육학회지 Vol.0 No.40
This study was conducted in order to see if there is a difference in health management index caused by Qigong training in elders who were participating in a Qigong training program as a part of the Oriental Medicine Public Health Project promoted by the Ministry for Health, Welfare and Family Affairs. The subjects of this study were 107 female elders aged 65 or older who were participating in the public health program of G City, Gyeonggi-do, and their health management index was determined using the change of self-perceived health, the change of health behaviors, medical equipment measurements, and physical measurements. Data collected from the tests before and after Qigong training were analyzed through paired sample t-test using SPSS and conclusions were drawn as follows. First, after Qigong training, the female elders` self-perceived health was enhanced significantly. Second, after Qigong training, the female elders` heath behaviors were improved significantly. After Qigong training, the female elders` blood pressure, blood sugar and bone density did not show any significant difference. Fourth, Qigong training had a significant effect on the female elders` body composition and flexibility. These results suggest that Qigong training has not only psychological effects but also physiological ones on female elders.