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김선태,이철구,김혜은,서정민,이석구,Kim, Seon-Tai,Lee, Cheol-Koo,Kim, Hea-Eun,Seo, Jeong-Meen,Lee, Suk-Koo 대한소아외과학회 2008 소아외과 Vol.14 No.1
Fundoplication is a common surgical procedure for gastroesophageal reflux disease (GERD). Recently the procedure has been performed with increased frequency laparoscopically. The aim of this study is to review our 11 years experience with fundoplication in infants and children. From October 1994 to December 2005, 59 fundoplications in 55 patients were performed at Sungkyunkwan University Samsung Medical Center. Medical records and laboratory results of these children were retrospectively reviewed for sex, age, symptoms and signs, coexisting disease, diagnostic methods, treatment modalities and length of operative time. Open fundoplication was performed in 41 cases and laparoscopic fundoplication in 18 cases. Simultaneous gastrostomy was done in 27 cases. Recurrent GERD symptom occurred in four patients (7.2 %) within 2 years after first fundoplication and all 4 patients had re-do fundoplication. There were no intra- and immediate post-operative complications. Gastrointesitnal symptoms were the most common indication for fundoplication in neurologically normal patients. The most frequent diagnostic studies were upper gastrointestinal series (76.3 %) and 24 hour esophageal pH monitoring (78.2 %). Fundoplication had been increased since 2004 and mostly done laparoscopically. In conclusion, our 11 years' practice of open and laparoscopic fundoplication indicates that both approaches are safe and effective in the treatment of GERD for infants and children.
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.
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.
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.
AZO 박막의 증착 및 열처리 조건에 따른 전기·광학적 특성
연응범,이택영,김선태,임상철,Yeon, Eung-Beom,Lee, Taek-Yong,Kim, Seon-Tai,Lim, Sang-Chul 한국재료학회 2020 한국재료학회지 Vol.30 No.10
AZO thin films are grown on a p-Si(111) substrate by RF magnetron sputtering. The characteristics of various thicknesses and heat treatment conditions are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Hall effect and room-temperature photoluminescence (PL) measurements. The substrate temperature and the RF power during growth are kept constant at 400 ℃ and 200 W, respectively. AZO films are grown with a preferred orientation along the c-axis. As the thickness and the heat treatment temperature increases, the length of the c-axis decreases as Al<sup>3+</sup> ions of relatively small ion radius are substituted for Zn<sup>2+</sup> ions. At room temperature, the PL spectrum is separated into an NBE emission peak around 3.2 eV and a violet regions peak around 2.95 eV with increasing thickness, and the PL emission peak of 300 nm is red-shifted with increasing annealing temperature. In the XPS measurement, the peak intensity of Al<sub>2p</sub> and O<sub>ll</sub> increases with increasing annealing temperature. The AZO thin film of 100 nm thickness shows values of 6.5 × 10<sup>19</sup> cm<sup>-3</sup> of carrier concentration, 8.4 cm<sup>-2</sup>/V·s of mobility and 1.2 × 10<sup>-2</sup> Ω·cm electrical resistivity. As the thickness of the thin film increases, the carrier concentration and the mobility increase, resulting in the decrease of resistivity. With the carrier concentration, mobility decreases when the heat treatment temperature increases more than 500 ℃.
Pechini법에 의한 Ga<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup> 형광체 분말의 제조
박인용,이종원,김선태,Park, In-Yong,Lee, Jong-Won,Kim, Seon-Tai 한국재료학회 2002 한국재료학회지 Vol.12 No.7
Europium-activated $Ga_2$$O_3$ phosphor powders were prepared by Pechini method from the mixed aqueous solutions of gallium(III) nitrate, europium(III) nitrate, ethylene glycol and citric acid. The phase formation process and particle shape of the powders obtained were investigated by means of TG/DTA, XRD and SEM. It was found that the powders were amorphous or ${\gamma}$-$Ga_2$$O_3$-like phase up to $500^{\circ}C$ and then transformed into $\beta$- $Ga_2$$O_3$ phase above $600 ^{\circ}C$. The powders calcined below $1000^{\circ}C$ were spherical and nanometer-sized. Photoluminescence spectra measured at room temperature showed that the highest luminescence intensity was obtained for the sample synthesized under the conditions of 2 mol% Eu concentration and heat treatment at $1000^{\circ}C$.