• Journal of the Korean Crystal Growth and Crystal Technology
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• 제21권4호
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• pp.169-174
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• 2011

Nanoscale-biodegradable behaviors of synthesized biphasic calcium phosphates (BCP) powders were characterized using X-ray diffraction (XRD), lattice parameter, and field emission microscopy (FE-SEM). The calcined BCP powders in vitro tested in Hank's balanced salt solution (pH = 7.4, $36.5^{\circ}C$) for 3 weeks. The calculated unit cell parameters for BCP have shown lattice distortion and expansion as irregular changes in the a and c-axis after in vitro.

• Journal of Digital Convergence
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• 제12권2호
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• pp.555-561
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• 2014

For five diagnostic X-ray generators (DR), four units turned out to be appropriate in tests on the reproducibility of radiation output suggested in the IEC 60601-2-54 standard, but in one unit of the X-ray equipment, an item measured in a combination of 50% of the highest tube voltage of the diagnostic X-ray equipment, the test setting of Group C with authorized output doses between $1{\mu}Gy$ and $5{\mu}Gy$ of mAs turned out to be inappropriate. As a result, the radiation dose to the IEC 60601-2-54 standard for quantification standards proposed by the radiation output from diagnostic X-ray imaging device reproducibility of performance management should be aware that an important evaluation factor.

• Journal of the Korean Society of Radiology
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• 제8권7호
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• pp.423-428
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• 2014

Digital X-ray imaging devices using a TFT based flat panel array has been used in medical field. But, recently, lots of research on the photon counting sensor has been reported. In this study, we evaluated the physical properties of the photoconductor by suggesting the standard and testing method for quantitative performance evaluation of photon counting x-ray imaging sensor. First, we measured the leakage current and the sensitivity of photon counting x-ray imaging sensor and we evaluated the characteristic of rising time for determining the signal shaping time. In addition, the set-up study was conducted on the basis of the IEC 62220-1-2 recommendations to define the number of incident photons per unit area. And the efficiency of the charge collection was also evaluated. As a result, the characteristic was measured as $200pA/mm^2$ of the leakage current, $7{\mu}C/cm^2R $ of the X-ray sensitivity, and $0.765{\mu}s$ of the rising time.

• Journal of radiological science and technology
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• 제11권2호
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• pp.27-64
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• 1988

Most hospital administrators in our country have doubted whether or not the size of their hospital personnel staffs, and the personnel management styles implemented are efficient or not. Actually, increased personnel expenditures due to sophisticated specialization of medical practices has become the biggest hospital expense. Therefore, it is said that hospitals can be run move efficiently by implementing reasonable management strategies for hospital personnel management. In this paper, the departments of diagnostic radiography in 16 general hospitals in Seoul, which were classified into 4 groups by the scale of hospital beds, were used as sample cases. Then, the data for the number of X-ray examination by diagnostic item was collected from sample hospitals. The unit hour spent on X-ray examinations in each diagnostic service was quoted from "A Study on setting-up of the relative value units of medical services and on the structure of current fee schedules" written by Mr. Ik Je Seong. The data analysis results are as follows; First, the number of hours per day spent on X-ray examinations in 13 hospitals out of 16 hospitals, was shorter than the general daily working hours (8 hours). Second, in the morning there was not enough time to work for X-ray examinations required, with the available manpower. In the afternoon, however, the situation was diametrically opposed to that in the morning. Third, in light of above results, though most hospitals employ sufficient personnel for the quantity of the actural work, they were always short-handed where their works were performed Fourth, this study tells us that there is a maldistribution of the work in the schedule : too much work for the available personnel in the morning. The following recommendations are resulted from the data analysis described above. First, it is recommended that all out-patients coming again, except specific patients(G. B. or I.V.P. etc) who have to have their X-ray examinations on an empty stomach in the morning among out-patients, be required to visit the hospital in the afternoon. Second, it is recommended that all new out-patients be required to make a reservation in order to equalize the number of patients throughout the day. Third, it is recommended that all in-patients, except specified patients, be arranged to have their X-ray examinations in the afternoon. Fourth, it is recommended that part time workers be employed during peak hours. This recommendation, if applied in a wider scale, would allow hospitals to overcome the problem of the maldistribution of work and personnel, and then more efficient hospital management through the appropirate personnel management procedures could be expected.

• Clean Technology
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• 제19권3호
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• pp.320-326
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• 2013

Nano-sized PtRu-Ni/VC and PtRu-Sn/VC electrocatalysts were synthesized by a one-step radiation-induced reduction (RIR) (30 kGy) process using distilled water as the solvent and Vulcan XC-72 as the supporting material. The obtained electrocatalysts were characterized by transmission electron microscopy (TEM), scanning electron microscope energy dispersive spectroscopic (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The catalytic efficiency of electrocatalysts was examined for oxygen reduction, MeOH oxidation and CO stripping decreased in the following order, Hydrogen stripping : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/VC$^{(R)}$ (E-TEK). MeOH oxidation : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/ VC$^{(R)}$ (E-TEK). Unit cell performance : PtRu-Sn/VC > PtRu-Ni/VC > PtRu/VC$^{(R)}$ (E-TEK) catalysts.

• Journal of the Korean Vacuum Society
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• 제21권6호
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• pp.348-353
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• 2012

We investigated chemical states of a $Sb_2Te_3$ thin film with the polycrystalline phase by using high-resolution x-ray photoelectron spectroscopy with synchrotron radiation. The $Sb_2Te_3$ thin film was formed by sputtering. The rhombohedral phase was confirmed by x-ray diffraction. To remove the surface oxide, we performed $Ne^+$ ion sputtering for 1 hour with the beam energy of 1 kV and post-annealing at $100^{\circ}C$ for 5 min in ultra-high vacuum. We obtained the Te and Sb 4d core-levels spectra with the peaks at the binding energies of 40.4 and 33.0 eV, respectively. The full-width of half maximum of both the Te and Sb $4d_{5/2}$ core-levels is 0.9 eV. The Te and Sb core-levels only show a single chemical state, and we also confirmed the stoichiometry of approximately 2 : 3.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제13권5호
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• pp.359-369
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• 2020

In this paper, we proposed a charge pump (CP) circuit that has a wide operating range while reducing the current mismatch for the PLL that generates the main clock of the CMOS X-Ray detector. The operating range and current mismatch of the CP circuit are determined by the characteristics of the current source circuit for the CP circuit. The proposed CP circuit is implemented with a wide operating current mirror bias circuit to secure a wide operating range and a cascode structure with a large output resistance to reduce current mismatch. The proposed wide operating range cascode CP circuit was fabricated as a chip using a 350nm CMOS process, and current matching characteristics were measured using a source measurement unit. At this time, the power supply voltage was 3.3 V and the CP circuit current ICP = 100 ㎂. The operating range of the proposed CP circuit is △VO_Swing=2.7V, and the maximum current mismatch is 5.15 % and the maximum current deviation is 2.64 %. The proposed CP circuit has low current mismatch characteristics and can cope with a wide frequency range, so it can be applied to systems requiring various clock speed.

• Journal of the Korean Chemical Society
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• 제55권4호
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• pp.697-702
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• 2011

The new layered perovskite manganites $La_{0.5}Sr_{1.5}Mn_{0.5}Cr_{0.5-x}Fe_xO_4$ (x=0.15, 0.3) have been prepared by standard ceramic method. The powder X-ray diffraction studies show that the phases crystallize with tetragonal unit cell in the space group I4/mmm. The electrical transport properties suggest that the phases show insulating behaviour and the electrical conduction in the phases occurs by a 3D variable range hopping mechanism. The magnetic properties suggest that both the phases are antiferromagnetic.

• Journal of the Korean Chemical Society
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• 제55권3호
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• pp.502-508
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• 2011

Synthesis of $Nd_{2x}Cd_{2-3x}SiO_4$ ($0.01{\leq}x{\leq}0.21$) [S1-S3: x=0.01, 0.11 and 0.21] solid solutions were prepared by solgel method. Powder x-ray diffraction (XRD) results show monoclinic unit cell with space group P21/m. The average crystallite sizes are found to be 20 to 45 nm. The Scanning Electron Microcopy (SEM) images show morphology of the sample is in globular nature. The energy dispersive analysis of x-rays (EDX) and X-ray mapping results confirmed that all the constituent elements of the composites were present and that were distributed in uniformly. The optical absorption band at ~750 nm was due to $^4I_{9/2}{\rightarrow}^4F_{7/2}+^4S_{3/2}$ transition optically active $Nd^{3+}$ ions. Electron Paramagnetic Resonance (EPR) lineshapes of S1-S3 at 10, 40, 77 and 300 K show a broad unresolved isotropic lineshapes were observed due to rapid spin lattice relaxation of $Nd^{3+}$.

• Elastomers and Composites
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• 제40권3호
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• pp.212-221
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• 2005

Polyurethanes containing mesogen unit (MPU-6) were prepared from 4,4'-diphenylmethane diisocyanate (MDI) and 4,4'-bis(6-hydroxy hexoxy)biphenyl (BP-6) having flexible chain composed of 6 carbons. Intrinsic viscosities of MPU-6s were in the range of $0.23{\sim}0.56 dL/g$. The mesomorphic behaviors of MPU-6 were observed in X-ray and polarizing microscopy analysis. However, MPU-6s demonstrated a 'virtual liquid crystal' behavior, which did not exhibit mesophase on slow heating and slow cooling. MPU-6 having lower molecular weight exhibited higher crystallization rate and melting crystallization temperature due to increased mobility of polymer chains. The increased mobility of polymer chains facilitate the orientation of mesogen units that may act as a nucleating agent.