• Journal of radiological science and technology
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• v.46 no.6
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• pp.519-526
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• 2023

This study was intended to evaluate the shielding rate of radiation shields manufactured using 3D printers that have recently been used in various fields by comparing them with existing shields made of lead, and to find out their applicability through experiments. A 3D printer shield made of tungsten filament 1 mm, 2 mm, 4 mm shield, RNS-TX (nanotungsten) 1.1 mm, lead 0.2 mmPb, and 1mmPb were exposed to ^99mTc, ¹⁸F, and ²⁰¹TI for 15, 30, 45 minutes, and 60 minutes after measuring cumulative dose three times. Based on this, the shielding rate of each shield was calculated based on the dose in the absence of the shield. In addition, ^99mTc, ¹⁸F, and ²⁰¹TI were located 100 cm away from the phantom in which the OSLD nano Dot device was inserted, and if there was no shield for 60 minutes, the dose of thyroid was measured using 1.0 mm of lead shield, 1.1 mm of RNS-TX shield, and 2 mm of tungsten shield made by 3D printer. The use of shields during radiation shielding emitted from open radiation sources all resulted in a reduction in dose. The radiation dose emitted from the radionuclides under the experiment was all reduced when the shield was used. This study has been confirmed that tungsten is a material that can replace lead due to its excellent performance and efficiency as shield, and that it even shows the possibility of manufacturing a customized shield using 3D printer.

• Membrane Journal
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• v.25 no.2
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• pp.191-201
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• 2015

We have studied on the preparation of $TiCo_xFe_{1-x}$(x=0.50~1.00) system alloy, the characteristics of $TiCo_xFe_{1-x}$(x=0.50~1.00) system alloy by X-ray diffractometer (XRD), pressure composition temperature (PCT) curve, scanning electron microscopy (SEM) and the $H_2-N_2$ gas mixture separation of $TiCo_xFe_{1-x}$(x=0.50~1.00)- stainless steel (SS) composite membranes. The formation of $TiCo_xFe_{1-x}$(x=0.50~1.00) system alloys with cubic crystal same as TiCo was confirmed by X-ray diffractometer. $TiCo_xFe_{1-x}$(x=0.50~1.00) system alloys showed the hysteresis at $120^{\circ}C$. As the Fe content of $TiCo_xFe_{1-x}$(x=0.50~1.00) system alloys increased, the hysteresis was increased both range x=0.90~1.00 and x=0.55~0.60, and the range x=0.55~0.90 gave decreased hysteresis. $TiCo_{0.55}Fe_{0.45}$ alloy was the one showed the lowest hysteresis among them. The lowest value of hydrogen permeation pressure of $TiCo_xFe_{1-x}$(x=0.50~1.00)-SS composite membrane was $TiCo_{0.55}Fe_{0.45}$-SS composite membrane with the value of 2.5 atm at $120^{\circ}C$; otherwise, $TiCo_{0.90}Fe_{0.10}$-SS composite had the highest pressure value among the membranes with the value of 10 atm. $TiCo_{0.55}Fe_{0.45}$-SS composite membrane was the best to separate the $H_2-N_2$ gas mixture excellently among the $TiCo_xFe_{1-x}$(x=0.50~1.00)-SS composite membranes since $TiCo_{0.55}Fe_{0.45}$ had the least hysteresis, and hydrogen permeation pressure was the lowest with value of 2.5 atm.

• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.201-206
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• 2002

Pd/Si/Pd/Ti/Au ohmic contact to n-type InGaAs was investigated with rapid thermal annealing conditions. Minimum specific contact resistivity of $3.9\times10^{-7}\Omega\textrm{cm}^2$ was achieved at $400^{\circ}C$/20sec. This was related to the formation of Pd-Si compounds by rapid thermal annealing and the in-diffusion of Si atoms to InGaAs surface. However, the specific contact resistivity increased slightly to low-$10^{-6}\Omega \textrm{cm}^2$ at $400^{\circ}C$ for longer than 30 seconds, and to high-$10^{-7}$ at 425~$450^{\circ}C$ for 10 seconds. This resulted from the formation of Pd-Ga compounds. Superior ohmic contact and non-spiking planar interface between ohmic materials and InGaAs were maintained after annealing at high temperature. Therefore, this thermally stable ohmic contact system is a promising candidate for compound semiconductor devices.

• Archives of Pharmacal Research
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• v.21 no.5
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• pp.496-502
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• 1998

The present study was carried out to determine the possible use of cTn-I in the cardiac myofibrillar architecture, as a potential target for in vivo radioimmunodetection of cardiac damage in a brain death pig model. Radioiodiantion of the anti-cTn-I 5F4 McAb was carried out by lactoperoxidase method. the percentage iodine incorporation achieved was 70-75%. The radioiodinated McAbs were purified on Sephadex G-25 column and characterised by Paper chromatography, Phast Gel electrophoresis and electroimmunoblotting. Radioiodinated anticTn-I 5F4 McAbs were employed alongside Pyrophosphate($Tc_{99m}$-PPi$) and $Thallium^{201}$ chloride($TI^{201}$) in 24 landrace pigs (brain-dead=18 & sham-operated=6). The percentage cardiac uptake of the radiolabelled antibody injected dose was significantly higher in the brain dead animals(0.196%) as compared to that of sham-operated animals (0.11%). Specific in vivo localization of radiolabelled McAbs in the infarcted cardiac tissue was confirmed by computer-aided reconstruction of 3-D images of the isolated heart. The preliminary results of the study revealed preferential uptake of radiolabelled antibody at the site of myocyte damage resulting from artificially induced brain death.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.194-201
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• 2016

Purpose: The purpose of this study was to evaluate of Zirconium Nitride (ZrN) coating on shear bond strength with denture base resin in Co-Cr and Ti-6Al-4V alloy. Materials and Methods: Co-Cr and Ti-6Al-4V alloy disks (10 mm in diameter, 2.5 mm in thickness; each other: n = 14) were prepared and divided with 2 groups each other by ZrN coating. After primer was applied to disks surface, denture base resin with diameter 6 mm, height 5 mm was bonded on metal disk surface. After surface roughness was measured by Profiler, shear bond strength was determined with Universal testing machine and analyzed with two-way ANOVA. The specimen surfaces and failure mode were examined using a scanning electron microscope. Results: ZrN coated groups showed significantly higher rough surface than non-coated groups (P < 0.05). Irrespective of alloy materials, shear bond strength of ZrN coated groups were lower than non-coated groups (P < 0.001). The scanning electron microscope (SEM) of ZrN coated groups showed mixed and adhesive fractures. Conclusion: ZrN coating weakened bonding strength between denture base resin and Co-Cr, Ti-6Al-4V alloy.

• Progress in Medical Physics
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• v.25 no.1
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• pp.8-14
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• 2014

The amounts of radioactive wastes to be disposed in the medical institute have been increased due to development of radiation diagnosis and therapy rapidly. They are produced mostly by the very short lived radioisotopes such as $^{18}F$ used in PET/CT, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}Tl$, etc. IAEA proposed a criteria for the clearance level of waste which depends on the individual ($10{\mu}Sv/y$) and collective dose (1 man-Sv/y), and concentration of each nuclide (IAEA Safety Series No 111-P-1.1, 1992 and IAEA RS-G-1.7, 2004). Radioactive wastes of $^{18}F$, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}TI$ in the several types of container like Marinelli beaker, vial and plastic, were collected to measure the concentration of the waste of each nuclide in accordance with IAEA criteria. The measurement method and procedure of determining specific activity of the wastes using gamma emitters like MCA, gamma counter and beta emitters were developed. For the efficiency calibration of the detectors, CRM (certified reference material) which has the same dimension and shape was provided by Korea Research Institute of Standards and Science (KRISS). Correction factor of the radioactivity decay was calculated based on the measurement results, and the consideration of mutual relation with theoretical equation. The result of this study will be proposed as ISO standard.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.405-412
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• 1993

This experiment was conducted to investigate the effects of water depths on seedling stand and early growth of califonia rice varieties, S201, M202, A301, Italico livorno and Korean variety, Hwaseongbyeo, and barnyardgrass (Echinochloa crus-galli) The coleoptile length of rice was longer with deep water depth while for the radicle length shorten. As water depth was increased, the percentage of seedling stand were decreased slightly in rice, while sharply increased in barnyardgrass. Plant height of rice with increasing water depth were longer, whereas that of barnyardgrass reduced significantly with weaker. Tiller number of rice and barnyardgrass were significantly reduced as water depth increased. Dry matter weight and healthy score of rice seedling at 35DAS were highest in 7.5cm water depth followed saturated moisture, 15, and 22.5cm water depth, while for barnyardgrass those were especially negatively affected by deep water depth. These results showed that the seedling stand and early growth of barnyardgrass was highly suppressed by deeper water levels compared with rice. Rice cultivars which are showes growth characteristics in deeper water levels at early growth stage were Italico livorno and S201 in Japonica / Indica.

• Toxicological Research
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• v.25 no.4
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• pp.195-201
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• 2009

Recent publications showed that metal nanoparticles which are made from $TiO_2,\;CeO_2,\;Al_2O_3,\;CuCl_2,\;AgNO_3$ and $ZnO_2$ induced oxidative stress and pro-inflammatory effects in cultured cells and the responses seemed to be common toxic pathway of metal nanoparticles to the ultimate toxicity in animals as well as cellular level. In this study, we compared the gene expression induced by two different types of metal oxide nanoparticles, titanium dioxide nanoparticles (TNP) and cerium dioxide nanoparticles (CNP) using microarray analysis. About 50 genes including interleukin 6, interleukin 1, platelet-derived growth factor $\beta$, and leukemia inhibitory factor were induced in cultured BEAS2B cells treated with TNP 40 ppm. When we compared the induction levels of genes in TNP-treated cells to those in CNP-treated cells, the induction levels were very correlated in various gene categories (r=0.645). This may suggest a possible common toxic mechanism of metal oxide nanoparticles.

• The Korean Journal of Nuclear Medicine
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• v.32 no.1
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• pp.1-9
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• 1998

Gated myocardial SPECT and attenuation correction gave birth to new insights into the pathophysiology of ischemic myocardial perfusion and function in clinical routine practice. Gated myocardial Tc-99m-compound SPECT improved diagnostic accuracy of coronary artery disease and enabled us to observe motion and thickening of myocardial walls as well as myocardial perfusion at the same time. Quantitative and qualitative assessment of myocardial performance and perfusion let us to understand the myocardial physiology in ischemia and infarction. In every patient who underwent gated perfusion SPECT, we will find ejection fraction, left ventricular volumes and regional wall motion. There are hopes to use gated TI-201 SPECT for the same purpose and to use gated SPECT for evaluation of wall motion and thickening at stress or immediate post-stress. Attenuation correction could improve diagnostic accuracy mainly by increasing normalcy ratio or performance of non-expert physicians. Both gated methods and attenuation correction improved specificity of non-expert physicians in diagnosing patients with moderate pretest likelihood. New imaging techniques will fill the desire of cardiologists to examine function and perfusion, and possibly metabolism in their clinical routine practice.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.201-203
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• 2005

A kinetic model for particle coarsening behavior in the weld heat affected zone (HAZ) was proposed. Unlike the conventional approach, where the mean-sized particle is considered to grow continuously, the proposed model considered the critical particle size which can be derived from the Gibbs-Thomson equation. In this study, the proposed particle coarsening model was applied to study the behavior of (Ti, Nb )(C, N) complex particle in the weld HAZ. The predicted particle size distributions using the proposed model were in agreement with the experimental results.