• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.70-75
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• 1997

An improved technique based upon an electron beam evaporation system has been developed to prepare cubic thin films In crystalline semiconductors. Zinc blonde CdSe epilayers were grown on GaAs(100) substrate by an e-beam evaporation method. The lattice parameter obtained from (400) reflection is $6.077\AA$, which is in excellent agreement with the value reported in the literature for zinc blonde CdSe. The orientation of the as-grown CdSe epilayer is determined by electron channeling patterns. The crystallinity of epitaxial CdSe layers were investigated on the double crystal X-ray rocking curve. The carrier concentration and mobility of epilayers deduced by Hall effect measurement are about $10^{18}{\textrm}{cm}^{-3}$, $10^2\textrm{cm}^2/V{\cdot}sec$ at room temperature, respectively. The photocurrent spectrum peak of the epilayer at 30 K exhibits a sharp change at 1.746 eV due to the free exciton of cubic CdSe.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.3
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• pp.101-104
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• 2008

GaN films were grown on the vertical and horizontal reactors by the hydride vapour phase epitaxy (HVPE). The structural and optical characteristics of the GaN films were investigated depending on the reactor-type. GaN epilayers were characterized by double crystal X-ray diffraction (DC-XRD), transmission electron microscopy (TEM) and photoluminescence (PL). Surface defects of two kinds of the GaN films were revealed by the wet chemical etching method, using $H_3PO_4$ acid at $200^{\circ}C$ for 8 minutes. Hexagonal etch pits were analyzed by optical microscopy and SEM. Etch pit densities were calculated to be approximately $1.4{\times}10^7$ and $1.2{\times}10^6\;cm^{-2}$ for GaN layers grown on horizontal and vertical reactors, respectively. Those results show GaN grown in the vertical reactor having a better quality of optical properties and crystallinity than that in the horizontal reactor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.574-579
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• 1999

A counter-flow type horizontal reactor of metal organic chemical vapor deposition was designed with the Reynolds and the Rayleigh numbers of Re = 4.5 and Ra = 215.8, respectively. The GaN thin films were grown and characterized by Hall measurement, double crystal X-ray diffraction analysis and photoluminescence measurement. The Si and Mg were also used for doping of GaN films. The dislocation density of $2.6{\times}10^8/\textrm {cm}^2$ was included in GaN films representing the geometrical lattice mismatch between sapphire substrates and GaN films. The Si doped n-GaN films provide the electron carrier density and mobility in the regions of $10^{17}~10^{18}/\textrm{cm}^3$ and 200~400 $\textrm{cm}^2$/V .sec, respectively. Mg doped p-GaN films were post-annealed and activated with the hole carrier density of $8{\times}10^{17}/{\textrm}{cm}^3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.125-126
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• 2006

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films. $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}cm^{-3}$. $345cm^2/V{\cdot}s$ at 293 K, respectively. From the photoluminescence measurement on $CdGa_2Se_4$ single crystal thin film, we observed free excition ($E_x$) existing only high quality crystal and neutral bound exiciton ($D^{\circ},X$) having very strong peak intensity. Then. the full-width-at -half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule. an activation energy of impurity was 137 meV.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.220-228
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• 1996

CdTe single crystals were grown by vertical Bridgman method using double furnace with two siliconit heating elements. When the peak temperature of the upper furnace was fixed at $1150^{\circ}C$ and that of the lower furnace was $800^{\circ}C$, the temperature gradient was about $22.5^{\circ}C$/cm. The lattice constant $a_0$ was $6.482\AA$ from the X-ray diffraction and the band gap energy obtained from the optical absorption experiment at room temperature was 1.478 eV. PL spectrum showed that the bound exciton emission peak was resolved into ($A^0,X$) (1.5902, 1.5887 eV), ($h\;D^0$) (1.5918 eV) and ($D^0,X$ (1.5928, 1.5932 eV), and we have also calculated binding energy and ionization energy of the neutral donor and acceptor.

• Journal of Korean Foot and Ankle Society
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• v.10 no.1
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• pp.24-30
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• 2006

Purpose: To present our treatment protocol and surgical outcome for patients with congenital brachymetatarsia in which treatment was decided according to the number of affected rays. Materials and Methods: Sixty-nine metatarsals in 44 patients with single or multiple congenital brachymetatarsia were included in the study. When a single ray was affected in a foot, we performed a one-stage lengthening using an intercalary autogenous iliac bone graft. We overcame excessively short rays by the double level lengthening at the metatarsal and proximal phalanx as one stage. When multiple rays were affected in one foot, we performed a one-stage combined shortening and lengthening procedure without an iliac bone graft. Results: All patients were satisfied with the cosmetic and functional results. The average length gain by one-stage lengthening in 56 metatarsals of 38 patients was 14 (6-21) mm. Six patients with a combined shortening and lengthening procedure regained a nearly normal parabola of the involved foot. Neurovascular complication was not identified. Conclusion: Satisfactory results were achieved for the treatment of patients with congenital brachymetatarsia, by individualizing the surgical options according to the number of affected rays and general foot appearance.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.137-141
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• 2005

The CMR properties and magnetic properties of sulphospinels $Zn_xFe_{1-x}Cr_2S_4$ have been explored by X-ray diffraction, magnetoresistance measurement, and $M\ddot{o}ssbauer$ spectroscopy. The crystal structures in the range of x=0.05, 0.1, 0.2 are cubic at room temperature. Magnetoresistance measurement indicates that these system is semiconducting below about 160 K. The temperature of maximum magnetoresistance is almost consistent with Curie temperature. The Zn substitutions for Fe occur to increase the Jahn-Teller relaxation and the electric quadrupole shift. CMR properties could be explained with Jahn-Teller effect, and half-metallic electronic structure, which is different from both the double exchange interactions of manganite La-Ca-Mn-O system and the triple exchange interactions of chalcogenide $Cu_xFe_{1-x}Cr_2S_4$.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.445-449
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• 1999

We studied the properties of the InAs epitaxial layers grown of (100)-oriented GaAs ($2^{\circ}$tilted toward[011]) by molecular beam epitaxy. From DCX (double-crystal x0ray), the better crystal quality was shown in InAs epitaxial layers on about 2500$\AA$ GaAs epitaxial layers on GaAs, we obtained the high mobility of InAs epitaxy in As/In BEP ratio (1.2~2.0) from Hall effect measurement. The electron mobility increased as electron concentration increases, until Si cell temperature $960^{\circ}C$$(N_D=2.21\times10^{-17}\textrm{cm}^{-3})$. The mobility decreases as the Si cell temperature increases, at the temperature over $960^{\circ}C$. We obtained the high mobility (1.10$\times$104cm2/V.s) at Si electron concentration of $N_D=2.21\times10^{-17}\textrm{cm}^{-3}$.

• Journal of Chest Surgery
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• v.26 no.9
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• pp.677-685
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• 1993

Experience with bileaflet mechanical valve replacement at the Inha Hospital in 192 patients, operated on from June 1986 until April 1993. Two hundred fourty-one prostheses [51 Duromedics, 79 St.Jude Medical, and 111 CafboMedics]were implanted during the total 195 operations. Mitral valve replacment[MVR]was done in 113 cases, aortic valve replacement[AVR]in 34, tricuspid valve replacement[TVR]in 2, and double valve replacement[DVR]in 46 cases.Of the total patients, 63.0% were women and 37.0% were men. The mean age of the patients was 40.8 years, ranged from 14 to 67years. Overall early mortality was 9.2\ulcorner%[18 out of 195]; 9.7%[11 out of 113]for MVR, 14,7% [5 out of 34]for AVR, and 4.3%[2 out of 46]for DVR. All of the operative survors were followed over a period of one to 83 months with a mean of 37 months, for total 543 patient-years. So far, eleven patients[6.7% of the long-term survivors]were lost to follov-up after a mean postoperative follow-up of 22.8 months. There were nine late deaths; three deaths due to prostetic valve endocarditis, two due to persistent heart failure, one due to cerebral hemorrhage, one due to aortic dissection after Bentall oreration, and two sudden deaths. Actuarial survival rate at 6.9 years was 94.8%, There were seventeen valve-related complications; three prosthetic valve thromboses, three thrombembolisms, three instances of prosthetic valve endocarditis, two paravalvular leakages, and six hemorrhagic complications related to anticoagulation. The actuarial rate of freedom from all valve-related complications at 6.9years was 91.3%. There were significant decreases in the heart size postoperatively that can be demonstrated by comparison of cardio-thoracic ratios on simple chest X-ray and left ventricle dimensions on echocardiography. We conclude that this midterm follow-up shows good results in terms of hemodynamics and durability although further long-term evaluations are mandatory.

• Korean Journal of Veterinary Research
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• v.31 no.3
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• pp.329-335
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• 1991

The filter elution technique was used to assay $^{60}Co$ $\gamma$ ray-induced DNA strand breaks(SB) in EL4 mouse leukemia cell and mouse spleen lymphocyte. The lymphocytes were stimulated with lipopolysaccharide (LPS, $20{\mu}g/ml$) to label $[^3H]$ thymidine. EL4 cells and lymphocytes in suspension were exposed at $0^{\circ}C$ to 0Gy, 1Gy, 5Gy, 10Gy or l5Gy for DNA single strand breaks(SSB) assay and 0Gy, 25Gy, 50Gy, 75Gy or 100Gy for DNA double strand breaks(DSB) assay of $^{60}Co$ radiation and elution procedure was performed at pH12.1 and 9.6. The number of DNA strand breaks increased with increasing doses of r rays. The strand scission factor(SSF) was estimated in each experiment (eluted volume 21ml). The slope of SSB EL4 cells was $0.01301{\pm}0.00096Gy^{-1}$ (n=5), the slope of SSB for lymphocytes was $0.01097{\pm}0.00091Gy^{-1}$ (n=5) and the slope of DSB for lymphocytes was $0.001707{\pm}0.0000573Gy^{-1}$ (n=5). Thus EL4 cells were more sensitive to induction of DNA SSB by ionizing radiation than lymphocytes (p<0.005). The ratio of slope of dose-response relationship (SSF versus dose) of lymphocytes DNA SSB as compared with the slope of DNA DSB was 6.4.