• Polymer(Korea)
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• v.29 no.2
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• pp.177-182
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• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Journal of the Korean Society of Radiology
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• v.8 no.2
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• pp.81-88
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• 2014

In diagnostic radiology, each part is examined through serial radiography in most cases of general radiography. However, the reality is that, as for diagnostic reference level, measured values have been set up only for AP projection of each part and lateral projection. In the clinical setting, cumulative dose is incurred by serial radiography of patients, and this can make comparison of diagnostic reference level and cumulative exposure dose impossible or can lead to underestimation of diagnostic reference level. In this study, measurement of cumulative dose of serial radiography of each part revealed that when converting entrance surface dose to effective dose in case it is included in the exposure field, cumulative dose measured from a maximum of 38.06% to a minimum of 0.23% of individual dose limitation of the public. Also, when converting entrance surface dose of each part that is not included in the exposure field into effective dose, it measured from a maximum of 5% to a minimum of 0.04% of individual dose limitation of the public. Results of this study show entrance surface dose substantially increases in serial radiography of each part. Therefore, it is deemed that hospitals need to establish diagnostic reference level specifically, and subdivision of radiography orders for patients is also required in order to reduce unnecessary inspections. Moreover, the need of accurate exposure field is emphasized in case of inspection of several parts.

• Journal of Yeungnam Medical Science
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• v.13 no.1
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• pp.22-31
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• 1996

It is difficult to get a satisfactory result for the correction of malunited fracture of zygoma. Triple osteotomy and reposition of malunited zygoma is accepted as the better surgical method than camouflage surgery by means of onlays, if the orbital floor is to be reconstructed. The surgical approach can be divided into bicoronal, periorbital, intraoral and old scar. In 7 patients with malunited fracture of zygoma, the authors used a limited approach through extension of periorbital incision and intraoral incision instead of wide exposure including bicoronal incision. And we performed triple osteotomy and advancement of zygoma complex. The patients were followed for 4.5 months with acceptable result, and this approach was an effective method for the relatively simple tripod type-malunited fracture of zygoma. The authors obtained following conclusions: 1. Preoperative evaluation through thorough measurement of X-rays, investigation of photographs and detail communication with the patients was an important process. 2. Through lateral extension of subciliary incision, lateral eyebrow and intraoral incision, we could obtain adequate exposure for triple osteotomy and advancement of zygoma. 3. The zygoma should be reduced and fixed in an overcorrected superior and medial direction. 4. Return of zygoma to its anatomical position was possible only when it is completely freed from the surrounding soft tissue including masseter. 5. We could not find any different results between autogenous calvareal bone graft and $Medpor^{(R)}$ insertion on the floor of orbit.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.4
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• pp.259-269
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• 2013

Applicability of ammonium molybdophosphate/iron oxides-polyacrylonitrile (AMP/IO-PAN) composites on the removal of radionuclides in the radioactive wastewater generated from nuclear power plants was investigated. The composites were characterized using the following analytical techniques: X-ray diffraction (XRD), Fourior transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), particle size analyzer (PSA), nitrogen adsorption-desorption and magnetic property measurement system (MPMS). 10wt% of AMP/IO-PAN composite has a saturation magnetization of 2.038 emu/g. Single-solute sorptions of Co, Sr and Cs onto 10wt% of AMP/IO-PAN composite were investigated. The maximum sorption capacities ($Q^0$) predicted by the Langmuir model on 10wt% of AMP/IO-PAN composite were 0.097, 0.086 and 0.66 mmol/g for Co, Sr and Cs, respectively. The maximum sorption capacities ($Q^0$) of Cs predicted by Langmuir model on 0, 10, 20 and 30wt% of AMP/IO-PAN composites were 0.702, 0.655, 0.602 and 0.559 mmol/g, respectively. The maximum sorption capacities ($Q^0$) of Cs decreased with increasing the iron oxide content in the AMP/IO-PAN composites.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.177-184
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• 2016

Recently linear accelerator of radiation therapy intensity modulated radiation therapy, stereotactic radiation therapy are widely used. Such radiation treatment techniques are generally difficult to exclude the small field by using the inverse treatment plan. It is necessary to dose an accurate measurement of characteristics of the small field. Thus, using different detectors to measure the volume of the effective percentage depth dose, beam profile, and the output factor of the small field was to evaluate the dose characteristics of each detector. Experimental results for the X-ray beam 6 MV energy beam quality($PDD_{20}/PDD_{10}$) is $10{\times}10cm^2$ Diode detector is as high as 2.4% compared to Pinpoint detector. All field size to lesser effective volume of Diode detector shows that it is far better than other detectors by more than 50% of small penumbra, therefore spatial resolution far excellent. In field size $2{\times}2cm^2$ Semiflex detector was measured about 2% less than the other detector. Field size $1{\times}1cm^2$ is that there is no judgment about the validity show the difference between 20%. Field size $1{\times}1cm^2$ from the measured values of the Diode detector and Pinpoint detector showed a 13% difference. Less than field size $3{\times}3cm^2$ the feed to the difference between the output factor of the effective volume of the detector to be used for the effective volume available to the detector.

• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.33-37
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• 2004

Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ has been studied with Mossbauer spectroscopy, x-ray diffraction, vibrating sample magnetometer (VSM), and magnetoresistance (MR) measurement. The crystal structure was determined to be a cubic spinel with lattice parameter a$_{0}$=9.9880 $\AA$. The MR measurements show a semiconductor behavior below 110 K and metal behaved above 100 K. The temperature dependence of magnetization of Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$ was reported. In addition to a large irreversibility between the zero-field-cooling (ZFC) and the field-cooling (FC) magnetization at applied field H=100 Oe, a cusp-like anomaly was observed in both the FC and ZFC curves. It shifted toward the lower temperature region with increasing magnetic field, and then showed convex type maximum at 110 K, under the applied field of 5 kOe. The Mossbauer spectra were measured from 15 K to room temperature. The asymmetric line broadening was observed for the sample Cu$_{0.1}$Fe$_{0.9}$Cr$_2$S$_4$, and it was considered to be dynamic Jahn-Teller relaxation. The charge state of Fe ions was ferrous in character. The unusual reduction of magnetic hyperfine field below 110 K was interpreted in terms of cancellation effect between the mutually opposite orbital current field (H$_{L}$) and Fermi contact field (H$_{C}$).

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.383-387
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• 2014

In this paper, for a new detection system development with the better accurate dose evaluation and beam distribution imaging using the small field irradiation of linear accelerator, the compound semiconductor based detection sensors were fabricated and the performance evaluation was investigated. The special particle-in-binder sedimentation was used for a large area film sensor fabrication. The detection properties for high energy x-rays were investigated from a dark current, an output current, a rising time, a falling time, and response delay measurement. The experimental results, the $TiO_2$ mixed $HgI_2$ sensor showed the best electrical characteristics than $PbI_2$, PbO, pure $HgI_2$. Linearity, repeatability, and accuracy tests from LINAC were tested, the $TiO_2$ mixed $HgI_2$ sensor showed the better performance than the commercially available dosimetry devices.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.13-20
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• 1998

The crystallographic and high frequency characteristics of $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ soft magnetic alloys were investigated under the magnetic field annealing. As-cast ribbon with which already imbedded nanocrystalline Fe-Si phase on the surface have a preferred orientation with (400) plane to surface and also with the [011] direction parallel to the ribbon length. The extra nanocrystalline Fe-Si phase appeared throughout at 45$0^{\circ}C$ in samples with or without the longitudinal magnetic field. However the formation of nanocrystalline phase does not appear on the suface layer until 50$0^{\circ}C$ annealing temperature under the transverse field. The cryststallization fraction of annealed samples with longitudinal magnetic field is higher than that of samples without magnetic field. When the transverse magnetic field is applied, the crystallization fraction does not increases but decreases until 50$0^{\circ}C$. However the crystallization of internal regions can be confirmed by X-ray diffraction measurement via tilting the sample. It was found that for all samples, the saturation induction were all same with 1.3 T. The coercive field of as-cast sample was 1.06 A/cm, but in annealed samples it decrease from 0.56 to 0.1 A/cm with increasing annealing temperature from 400 and 55$0^{\circ}C$, respectively. The squareness of annealed samples under transverse magnetic field has a small value than that of both without field and with longitudinal field annealing.

• Progress in Medical Physics
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• v.17 no.4
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• pp.187-191
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• 2006

The purpose of this study was to measure the dose distribution from the moving phantom for the respiratory motion. The phantom for TLD measurement was designed and built for this study based on the multiple plates for placing TLD and film. The TLDs may be inserted at 3 mm intervals in each TLD plate. For the measurements, TLD plate was inserted into the phantom at 1.5 cm ($d_{max}$) depth, and phantom was allowed to move in SI directions in the range of 1 to 2 cm with 0.5 cm interval for 6 MV X-ray beams. Penumbra and FWHM were measured at both moving state and compared stationary. It was found that penumbra increased 0.71 cm at stationary and 2.10 cm at moving state in 2 cm movement, and that FWHM are 7.52 cm for stationary state and 7.02 cm for moving state (2 cm movement). In this study, film was used to compared with TLD results of measurements and simitar results were observed. Therefore, it is expected that TLD moving phantom may be useful for the treatment of tumors that move due to the respiratory motion.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.179-190
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• 2016

X-ray diffraction analysis, chromaticity measurement, execution and evaluation by Dancheong artisan, accelerated weathering test, and fire resistance test were conducted to test the applicability as a Dancheong pigment raw materials of Korean low grade kaolin in cultural properties. The ores that feldspar rich and composed of fine particles (< $38.1{\mu}m$) showing advantageous for the inherent purpose of the white pigment than that of high grade kaolin. And the test of whiteness, concealment force, outdoor exposure durability and fire resistance shows similar or better result than existing products (Hobun and Sanhwa jidang). In conclusion, it is expected that the use of fine feldspar rich white soil and low-grade kaolin can be used as a white pigment raw materials which have similar to better material properties and economic efficiency than existing products.