• Progress in Medical Physics
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• v.23 no.4
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• pp.279-284
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• 2012

The X ray has been widely used in both diagnosis and treatment. Recently, a miniature X ray tube has been developed for radiotherapy. The miniature X ray tube is directly inserted into the body irradiated, so that X rays can be guided to a target at various incident angles according to collimator geometry and, thus, minimize patient dose. If such features of the miniature X ray tube can be applied to development of X ray imaging as well as radiation treatment, it is expected to open a new chapter in the field of diagnostic X ray. However, the miniature X ray tube requires an added filter and a collimator for diagnostic purpose because it was designed for radiotherapy. Therefore, a collimator and an added filter were manufactured for the miniature X ray tube, and mounted on. In this study, we evaluated beam characteristics of the miniature X ray tube for diagnostic X ray system and accuracy of measuring the HVL. We used the Si PIN Photodiode type Piranha detector (Piranha, RTI, Sweden) and estimated the HVL of the miniature X ray tube with added filter and without added filter. Through an another measurement using Al filter, we evaluated the accuracy of the HVL obtained from a direct measurement using the automatic HVL calculation function provided by the Piranha detector. As a result, the HVL of the miniature X ray tube was increased around 1.9 times with the added filter mounted on. So we demonstrated that the HVL was suitable for diagnostic X ray system. In the case that the added filter was not mounted on, the HVL obtained from use of the automatic HVL calculation function provided by Piranha detector was 50% higher than the HVL estimated using Al filter. Therefore, the HVL automatic measurement from the Piranha detector cannot be used for the HVL calculation. However, when the added filter was mounted on, the HVL automatic measurement value using the Piranha detector was approximately 15% lower than the estimated value using Al filter. It implies that the HVL automatic measurement can be used to estimate the HVL of the miniature X ray tube with the added filter mounted on without a more complicated measurement method using Al filter. It is expected that the automatic HVL measurement provided by the Piranha detector enables to make kV-X ray characterization easier.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.3
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• pp.138-143
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• 2002

In this study, ZnS: Cu nano-crystals are synthesized by solution synthesis technique (SST). The structural properties such as crystal structure and particle morphology, and the optical properties such as light absorption/transmittance, energy bandgap, and photoluminescence (PL) excitation/emission are investigated. In an attempt to realize the Cu-doping easiness, the synthesis temperature (~$80^{\circ}C$) is applied to the synthesis bath, and the thiourea is used as sulfur precursor, unlike other general chemical synthesis route. Both undoped ZnS and ZnS : Cu nano-crystals have the cubic crystal structure and have the spherical particle shape. The position of light absorption edge is ~305 nm, indicating the occurrence of quantum size effect. The PL emission intensity and line-width are maximum and minimum, respectively, for Cu-doping concentration 0.03M. In particular, the dependence of PL intensity and line-width on the Cu-doping concentration for ZnS : Cu nano-crystals synthesized by SST is reported for the first time in this study. Experimental results of the absorption edge and the PL excitation show that the main emission peak of ZnS : Cu nano-crystals (~510 nm) in this study is due to the radiative recombination center in the energy bandgap induced by Cu dopant.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.15-20
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• 2007

We fabricated ZnO thin films on quartz substrate using pulsed laser deposition method and investigated structural and optical properties of ZnO thin films with various substrate temperatures. Regardless of the substrate temperature variation, all ZnO thin films had grown to (002) and the thin film deposited at 400 $^{\circ}C$ exhibited an excellent crystallinity having 0.24$^{\circ}$ of Full-Width-Half-Maximum (FWHM). In the result of photoluminescence property, UV and deep-level emission peaks were observed in all ZnO films and the emission peaks were changed with various substrate temperatures. An highest UV emission was exhibited on the specimen deposited at 400 $^{\circ}C$ and the FWHM of UV peak was 14 nm. The optical transmittance was about 85 % in visible region regardless of the substrate temperature. The comparison result of the bandgap energies obtained from optical transmittance and UV emission centers, the two values were about the same. From these results, it is found that UV emission center has close relationship with near band edge emission of ZnO thin film.

• Radiation Oncology Journal
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• v.8 no.1
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• pp.115-124
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• 1990

The characteristics of 23 MV photon beam have been presented with respect to clinical parameters of central axis depth dose, tissue-maxi mum ratios, scatter-maximum ratios, surface dose and scatter correction factors. The nominal accelerating potential was found to be $18.5\pm0.5$ MV on the central axis. The half-value layer (HVL) of this photon beam was measured with narrow beam geometry from central axis, and it has been showed the thickness of $24.5\;g/cm^2$. The tissue-maximum ratio values have been determined from measured percentage depth dose data. In our experimental dosimetry, the surface dose of maximum showed only $9.6\%$ of maximum dose at $10\times10\;cm^2$, 100 cm SSD, without blocking tray in. The TMR'S of $0\times0$ field size have been determined to get average $2.3\%$ uncertainties from three different methodis; are zero effective attenuation coefficient, non-ilnear least square fit of TMR's data and effective linear attenuation coefficient from the HVL of 23 MV photon beams of dual energy linear accelerator.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.141-145
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• 2009

Cheongyukjang, a Banga food, is a heavy soy-soup prepared by boiling cheonggukjang, sea foods, and meats. Soybeans roasted at 140$^{\circ}C$ for 21.0 min and 220$^{\circ}C$ for 6.0 min, respectively, were used for cheonggukjang preparation. Distributions of isoflavones in raw soybeans, roasted soybeans, cheonggukjang, and cheongyukjang were analyzed by high performance liquid chromatography. The total isoflavones in roasted soybeans, cheonggukjang and cheongyukjang were about 79-80, 56-65, and 47-50% of those in raw soybeans, respectively. Roasting caused significant increases in acetyl derivatives and ${\beta}$-glucoside isoflavones, and significant decreases in malonyl derivatives (p < 0.05). The major isoflavones in cheonggukjang and cheongyukjang were ${\beta}$-glucosides. Succinyl-${\beta}$-daidzin and succinyl-${\beta}$-genistin, which are recognized as new metabolites of isoflavones, were not detected in raw and roasted soybeans. Peak areas of succinyl-${\beta}$-genistin were higher than thse of succinyl-${\beta}$-daidzin, in both cheongyukjang and cheonggukjang.

• Polymer(Korea)
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• v.25 no.4
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• pp.521-527
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• 2001

The miscibility, molecular interaction and tensile properties of the blends of poly (${\varepsilon}$-caprolactone) (PCL) with poly(vinyl chloride) (PVC) have been studied. The measured glass transition temperature values of PCL/PVC blends were found to be well fitted by Fox equation. We found that PCL/PVC blends are amorphous up to 23% PCL content. The blends showed the highest Young's modulus and yield strength at 5% PCL content and the highest tensile strength at 11% PCL content. The blends with low contents of PCL(up to 13%) show increased tensile strength and decreased elongation of PCL/PVC blends. Consequently, the antiplasticization phenomenon is observed in the PCL/PVC blends.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.61-66
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• 2022

The purpose of this study is to derive photon energy fluence and mass energy absorption coefficient for 1 Gy of absorbed dose of water in brachytherapy using an Ir¹⁹² source. From the radiotherapy physics written by Khan, the half-value of lead for the gamma ray beam of the Ir¹⁹² source was obtained. The linear attenuation coefficient and the mass attenuation coefficient were calculated from the obtained half-value layer of lead. By matching the calculated lead mass attenuation coefficient with the NIST mass attenuation coefficient data, the photon energy of the matching mass attenuation coefficient was determined as the effective energy. By matching the determined effective energy with the photon energy of the NIST data on the mass energy absorption coefficient of water, the mass energy absorption coefficient of water was obtained as 0.03273 cm²/g(32.73 cm²/kg). The photon energy fluence was calculated as 0.03055 J/cm² by dividing the obtained mass energy absorption coefficient (32.73 cm²/kg) by the absorbed dose of water 1 Gy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.172-180
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• 2019

In this study, the microstructure and gamma-ray shielding efficiency of CRT glass mortar specimen were evaluated with replacement ratio and material properties. The results show that as the replacement ratio of CRT waste glass increases, the volume of pores with diameters below 50 nm and above 400 nm is increased. Also, the half-value layer of CRT glass mortar decreased with the increasing of linear attenuation coefficient. In addition, compressive and flexural strength were reduced when CRT waste glass was replaced as the fine aggregate, but the mechanical performance of CRT mortar specimen could be obtained by substitution of the mineral admixture.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8394-8399
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• 2015

The paper studies on the site and space composition of Lee Ha-Bock's traditional thatched roof house. The house is located at a site with back to the mountain and facing the water and the rear and front mountains formulate a shape of Myungeonhyung(a sleeping dog figure) with HyungGug theory of Pungsu. The house has ㄱ shaped Anchae, ㅡ shaped Sarangchae and Gwangchae. Those are formulate ㅁ lay out followed the land form. Through the research I found the house shows a typical traditional farmhouse in the middle of Korea of Josen period. Nowadays there are many large Giwajip(tile roofed house) of Josen period is remained but only a few thatched-roof house is lived. In this situation, the house has considerable architectural values as a traditional thatched roof house.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.79-86
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• 2004

This paper proposes a dual band Voltage Controlled Oscillator(VCO) with a standard 0.3${\mu}{\textrm}{m}$ CMOS process to generate 1.07GHz and 2.07GHz. The proposed VCO architecture with 50% duty cycle circuit and a half adder(HA) was capable of producing a frequency two times higher than that of the conventional VCOs. The measurement results demonstrate that the gain of VCO and power dissipation are 561MHz/V and 14.6mW, respectively. The phase noises of the dual band VCO are measured to be -102.55dBc/Hz and -95.88dBc/Hz at 2MHz offset from 1.07GHz and 2.07GHz, respectively.