• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.498-504
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• 2012

Oxide layers were prepared by an environmentally friendly plasma electrolytic oxidation (PEO) process on an Al-1050 substrate. The electrolyte for PEO was an alkali-based solution with $Na_2SiO_3$ (8 g/L) and NaOH (3 g/L). The influence of the electrical parameters on the phase composition, microstructure and properties of the oxide layers formed by PEO were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The voltage-time responses were recorded during various PEO processes. The oxides are composed of two layers and are mainly made of ${\alpha}$-alumina, ${\gamma}$-alumina and mullite phases. The proportion of each phase depends on various electrical parameters. It was found that the surface of the oxides produced at a higher current density and Ia/Ic ratio shows a more homogeneous morphology than those produced with the electrical parameters of a lower current density and lower Ia/Ic ratio. Also, the oxide layers formed at a higher current density and higher Ia/Ic ratio show high micro-hardness levels.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.540-544
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• 2017

In this study, we analyzed the effects of TID(Total Ionizing Dese) and TREE(Transient Radiation Effects on Electronics) on nMOSFET and pMOSFET fabricated by 0.18um CMOS process. The size of nMOSFET and pMOSFET is 100um/1um(W/L). The TID test was conducted up to 1 Mrad(Si) with a gamma-ray(Co-60). During the TID test, the nMOSFET generated leakage current proportional to the applied dose, but that of the pMOSFET was remained in a steady state. The TREE test was conducted at TEST LINAC in Pohang Accelerator Laboratory with a maximum dose-rate of $3.16{\times}10^8rad(si)/s$. In that test nMOESFET generated a large amount of photocurrent at a maximum of $3.16{\times}10^8rad(si)/s$. Whereas, pMOSFETs showed high TREE immunity with a little amount of photocurrent at the same dose rate. Based on the results of this experiment, we will progress the research of the radiation hardening for CMOS unit devices.

• Korean Journal of Oriental Medicine
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• v.9 no.2
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• pp.107-119
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• 2003

In this study, Kami-honghwa-tang (KH-19) was designed and animal study was conducted to evaluate its efficacy on the reduction of the side effect of radiotherapy. Bone marrow toxicity is one of the major side effect of radiotherapy which cause the reduction of blood cells, and KH-19 was designed to protect and enforce blood. C57BL/6 mice were irradiated with 4 Gy of gamma ray, and divided into control group which was treated with water and KH-19 group which was treated with 1.5g/Kg of KH-19 up to 4 weeks. KH-19 group showed significantly increased white blood cells, lymphocytes and platelet count compared with control group (p<0.05). When bone marrows were examined, KH-19 group showed higher cell densities than control group (p=0.06). KH-19 may increase blood cell count after radiation by its protective effects on bone marrow.

• Journal of Sensor Science and Technology
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• v.19 no.6
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• pp.443-448
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• 2010

In this work, the scintillation properties of CsI:Na crystal were investigated as radiation detection sensor. This scintillation material was grown by a 2-zone vertical Bridgman method. Under X-ray excitation the crystal shows a broad emission band between 280 nm and 690 nm wavelength range, peaking at 413 nm. Energy resolution for $^{137}Cs$ 662 keV $\gamma$-rays of the crystal was measured to be 6.9 %(FWHM). At room temperature, the crystal exhibits three exponential decay time components. The fast and major component of scintillation time profile of the crystal emission decays with a 457 ns time constant. Absolute light yield of the crystal was estimated to be 53,000 ph/MeV using LAAPD. The sample crystal shows proportionality of 30 % in the measured energy range from 31 to 1,333 keV. And the $\alpha/\beta$ ratio of the crystal was 0.14.

• Journal of Pharmaceutical Investigation
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• v.4 no.4
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• pp.17-25
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• 1974

1. Neutron acivation analysis of arsenic contained in Korean human liver was studied in the view point of forensic chemistry, using 12 corpses. A sample of 1g was irradiated for 30 mins. in a neutron flux of $1.2{\times}10^{12}n/cm^2/sec$, followed by nitric-sulfuric acid digestion and then by Gutzeit separation. Radio activity was detected by it's scintillation counter. The arsenic content in the liver was found to be $0.01{\mu}g/g$ to $0.15{\mu}g/g$. 2. A rapid and convenient method for the radiochemical determination of minerals by neutron activation analysis was established. After neutron irradiation to the standard soln. of Cu and Mn in pneumatic tube (neutron flux : $1.2{\times}10^{12}n/cm^2/sec$), Cu and Mn were determined by estimating the ratio of the widths under energy peak area in ${\gamma}-ray-spectrogram$. When the standard soln. of Mn and Cu is irradiated for 15 mins. to 18 hrs., recovery test shows that the relative errors are 5.1% and 4.5% for copper and manganese, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.10
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• pp.73-77
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• 1971

The experiment was carried out to investigate post-irradiation storage effect which was related to temperature(i.e. at 2$^{\circ}C$, 17$^{\circ}C$ and 4$0^{\circ}C$) on wheat seeds; Weibull's Svenno, treated with gamma-ray and fast neutron. Results obtained showed that the seedling height in both radiation sources was decreased with prolongation of storage period, especially when the seeds were treated with high dosage and stored at high temperature(4$0^{\circ}C$). The results of this trial, however, showed that storage effect was influenced by irradiation dose, temperature and storage time.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.619-623
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• 1999

The C-terminal starch-binding domain of Bacillus cereus $\beta$-amylase expressed in Escherichia coli was purified and crystallized using the vapor diffusion method. The crystals obtained belong to a space group of $P3_2$ 21 with cell dimensions, a=b=60.20${\AA},\; c=64.92{\AA},\; and \; \gamma = 120^{\circ}$ The structure was determined by the molecular replacement method and refined at 1.95 ${\AA}$, with R-factors of 0.181. The final model of the starch-binding domain comprised 99 amino acid residues and 108 water molecules. The starch-binding domain had a secondary structure of two 4-stranded antiparallel p-sheets similar to domain E of cyclodextrin glucanotransferase and the C-terminal starch-binding domain of glucoamylase. A comparison of the structures of these starch-binding domains revealed that the separated starch-binding domain of Bacillus cereus $\beta-Amylase$had only one starch-binding site (site 1) in contrast to two sites (site 1 and site 2) reported in the domains of cyclodextrin glucanotransferase and glucoamylase.

• Journal of Surface Science and Engineering
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• v.34 no.2
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• pp.161-168
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• 2001

A Thermal Barrier Coating (TBC) can play an important role in protecting parts from harmful environments at high temperatures such as oxidation, corrosion, and wear in order to improve the efficiency of aircraft engines by lowering the surface temperature of the turbine blade. The TBC can increase the life span of the product and improve the operating properties. Therefore, in this study the mechanical and thermal properties of the TBC such as oxidation, fatigue and shock at high temperatures were evaluated. A samples of a bond coat (CoNiCrAlY) produced by the High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness of the HVOF coating layer was approximately $450\mu\textrm{m}$ to 500$\mu\textrm{m}$ and the hardness number of the coating layer was between 350Hv and 400Hv. The thickness of the LPPS coating was about 350$\mu\textrm{m}$ to 400$\mu\textrm{m}$ and the hardness number of the coating was about 370Hv to 420Hv. The X-ray diffraction analysis showed that CoNiCrAlY coating layer of the HVOF and LPPS was composed of the $\beta$and ${\gamma}$phase. After the high temperature oxidation test, the oxide scale with about l0$\mu\textrm{m}$ to 20$\mu\textrm{m}$ thickness appeared at the coating surface on the Al-depleted zone was observed under the oxide scale layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.344-348
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• 2004

The CdSe thin films wee grown on the Si(100) wafers by a hot wall epitaxy method(HWE). The source and substrate temperature are $600^{\circ}C\;and\;430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the timperature range 30K to 150K by impurity scatering and decreased in the temperature range 150K to 293K by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^7$, the MAPD of 335mV, and the rise and decay time of 10ms and 9.5ms, respectively

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.304-308
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• 2004

The $Cd_{1-x}Zn_xS$ thin films were grown on the Si(100) wafers by a hot wall epitaxy method(HWE). The source and substrate temperature are $600^{\circ}C\;and\;440^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the $Cd_{0.53}Zn_{0.47}S$ samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.65{\times}10^7$, the MAPD of 338mW, and the rise and decay time of 9.7ms and 9.3ms, respectively