• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.67-70
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• 2013

Purpose: Surge in patients with hepatocellular carcinoma, hepatic artery chemical embolization is one of the effective interventional procedures. The PET/CT examination plays an important role in determining the presence of residual cancer cells and metastasis, and prognosis after embolization. The other hand, the hepatic artery chemical embolization of embolic material used lipiodol produced artifacts in the PET/CT examination, and these artifacts results in quantitative evaluation influence. This study, the radioactivity density and the percentage error was evaluated by the extent of the impact of lipiodol in the image of PET/CT. Materials and Methods: 1994 NEMA Phantom was acquired for 2 minutes and 30 seconds per bed after the Teflon, water and lipiodol filled, and these three inserts into the enough to mix the rest behind radioactive injection with $20{\pm}10MBq$. Phantom reconfigure with the iterative reconstruction method the number of iterations for two times by law, a subset of 20 errors. We set up region of interest at each area of the Teflon, water, lipiodol, insert artifact occurs between regions, and background and it was calculated and compared by the radioactivity density(kBq/ml) and the% Difference. Results: Radioactivity density of the each region of interest area with the teflon, water, lipiodol, insert artifact occurs between regions, background activity was $0.09{\pm}0.04$, $0.40{\pm}0.17$, $1.55{\pm}0.75$, $2.5{\pm}1.09$, $2.65{\pm}1.16 kBq/ml$ (P <0.05) and it was statistically significant results. Percentage error of lipiodol in each area was 118%, compared to the water compared with the background activity 52%, compared with a teflon was 180% of the difference. Conclusion: We found that the error due to under the influence of the attenuation correction when PET/CT scans after lipiodol injection performed, and the radioactivity density is higher than compared to other implants, lower than background. Applying the nonattenuation correction images, and after hepatic artery chemical embolization who underwent PET/CT imaging so that the test should be take the consideration to the extent of the impact of lipiodol be.

• The Journal of the Petrological Society of Korea
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• v.17 no.2
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• pp.95-107
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• 2008

The Carved Buddhist Triad on Rock-cliff in Sinarnri (Treasure No. 680) consists of biotite granodiorite, which were positively carved on fore and west planes of four subvertical cliffs by two joint sets of NE-SW and NNW-SSE directions. The cliffs are $N50^{\circ}E\;85^{\circ}SE$ in fore plane, $N25^{\circ}W\;90^{\circ}$ in west plane, $N40{\sim}50^{\circ}E\; 82{\sim}85^{\circ}NW$, back plane, $N20^{\circ}W\;75^{\circ}SW$ in east plane, which are parallel to two joint sets of NE-SW and NNW-SSE directions in geology around it. The chemical index of alteration ranges 60.3 to 62.0 from the major elements in the rock that was weathered into producing kaolin minerals from alteration of feldspars and biotite. The Buddhist image has been deteriorated into joints, brown rusts, discolorations and granular disintegrations by such deterioration causes as deformation, moisture, temperature variation and microorganic living. The moisture, which leaks from groundwater in the rock, dissolve to decompose minerals.

• The Korean Journal of Nuclear Medicine
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• v.30 no.3
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• pp.344-350
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• 1996

Purpose : Noninvasive imaging of tumor cell proliferation could be helpful in the evaluation of tumor growth potential and could provide an early assessment of treatment response. Radiolabeled thymidine, uridine and adenosine have been used to evaluate tumor cell proliferation. These nucleoside analogs are incorporated into DNA during proliferation. Iodine-131-Iodomethyluridine, an analog of Iodine-131-Iododeoxyuridine, is also involved in DNA/RNA synthesis. The purpose of this study was to develop Iodine-131-Iodomethylurdine and image tumor proliferation using Iodine-131-Iodomethyluridine. Materials and Methods : Radiosynthesis of Iodine-131-5-Iodo-2'-O-methyluridine (Iodine-131-Iodomethyluridine) was prepared from 10 mg of 2'-O-methyluridine(Sigma chemical Co., St. Louis, Missouri) and 2.1 mCi(SP. 10Ci/mg) of Iodine-131-labeled sodium iodide in $100{\mu}l$ of water using iodogen reaction. Female Fischer 344 rats were inoculated in the thigh area with breast tumor cells(13765 NF, $10^5$ cells/rat S.C.). After 14 days, the Iodine-131-Iodomethyluridine $10{\mu}Ci$ was injected to three groups of rats(3/group). The percent of injected dose per gram of tissue weight was determined at 0.5-hours, 2-hours, 4-hours, and 24-hours respectively. Tumor bearing rats after receiving Iodine-131-Iodomethyluridine($50{\mu}Ci$ IV) were euthanized at 2 hours after injection. Autoradiography was done using freeze-dried $50{\mu}m$ coronal section. After injection of Iodine-131- Iodomethyluridine ($10{\mu}Ci$/rat, IV) in three breast tumor-bearing rats, planar scintigraphy was taken at 45 minutes, 90 minutes and 24 hours. Results : Iodine-131-Iodomethyluridine was conveniently synthesized using iodogen reaction. The biodistribution showed fast blood clearance and the tumor-to-tissue uptake ratios showed that optimal imaging time was at 2 hours postinjection. Autoradiogram and planar scintigram indicated that tumor could be well visualized. Conclusion : The findings suggest that Iodine-131-Iodomethyluridine, a new radio-iodinated nucleoside, has potential use for evaluation of active regions of tumor growth.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1005-1013
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• 2010

This study was conducted to assess the spray control of flash boiling with mixed fuel in consideration of HCCI (Homogeneous Charge Compression Ignition) engine condition. Mixed fuel existing in two phase regions can control the process of mixture formation under low temperature and density by using the spray resulting from flash boiling which is able to induce rapid evaporation of fuel spray as well as the evaporation of high boiling point component. Because HCCI engine injects the fuel early under ambient conditions, it can facilitate the chemical control of ignition combustion and physical control such as breakup and atomization of liquid fuel by flash boiling of mixed fuel which consists of highly ignitable light oil and highly volatile gasoline. This study was conducted by performing video processing after selected composition and molar fraction of the mixed fuel as major parameters and photographed Schlieren image and Mie scattered light corresponding to the flash boiling phenomenon of the fuel spray that was injected inside a constant volume vessel. It was found that flash boiling causes significant changes in the spray structure under relatively low temperature and density. Thus, we analyzed that the flash boiling spray can be used for HCCI combustion by controlling the mixture formation at the early fuel injection timing.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.31-38
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• 2008

Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective $\pi$/2-pulse and $\pi$-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing $\pi$-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was $301.50s/mm^2$. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = $963.90{\pm}79.83({\times}10^{-6}mm^2/s)$ at 0.32 T, $956.77{\pm}4.12({\times}10^{-6}mm^2/s)$ at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.3
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• pp.275-281
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• 2004

Socket weldment used to change the flow direction of fluid nay have flaws such as lack of fusion and cracks. Liquid penetrant testing or Radiography testing have been applied as NDT methods for flaw detection of the socket weldment. But it is difficult to detect the flaw inside of the socket weldment with these methods. In order to inspect the flaws inside the socket weldment, a ultrasonic testing method is established and a ultrasonic transducer and automated ultrasonic testing system are developed for the inspection. The automated ultrasonic testing system is based on the portable personal computer and operated by the program based Windows 98 or 2000. The system has a pulser/receiver, 100MHz high speed A/D board, and basic functions of ultrasonic flaw detector using the program. For the automated testing, motion controller board of ISA interface type is developed to control the 4-axis scanner and a real time iC-scan image of the automated testing is displayed on the monitor. A flaws with the size of less than 1mm in depth are evaluated smaller than its actual site in the testing, but the flaws larger than 1mm appear larger than its actual size on the contrary. This tendency is shown to be increasing as the flaw size increases. h reliable and objective testing results are obtained with the developed system, so that it is expected that it can contribute to safety management and detection of repair position of pipe lines of nuclear power plants and chemical plants.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.1-7
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• 2019

Most oil refineries and chemical plants have flare systems designed to mitigate pressure rises in process facilities in case of emergencies that require the release of large amounts of gas due to sudden process shutdowns such as power outages. However, the rise of the flame of the flare system causes civil complaints from residents around the factory due to visible pollution, and economic loss occurs in the company, which requires constant management. In this study, two items were diagnosed and analyzed in order to derive the optimal operation method of flare system. First, to detect the cause of the rise in flame height, the acoustic leak detector was used to check gas leaks in safety valves and pressure control valves. Second, to identify the cause of flame instability, the pulsation phenomenon was diagnosed through the CFD simulation and modeling experiments of the sealing drum. By confirming the leak at 4.3% of the safety valve and 10% of the pressure control valve, the cause of abnormal sparking was derived. The information presented in this study can be easily applied to any company that has a flare system, and is expected to prevent complaints and product loss.

• Journal of Veterinary Clinics
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• v.27 no.3
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• pp.216-219
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• 2010

The purpose of this study is to establish experimental canine skin barrier disruption model, the study was designed to observe calcium ion in skin frozen tissue of canine skin and also the modulation of calcium ion distribution of normal skin with disrupted skin such as clipping, acetone, tape stripping damages according to time. To compare the changes of calcium ion gradient after damages, the distribution of calcium ion in the canine epidermis was visualized by blotting to gel containing chemical indicator (Calcium Green-1) with fluorescent microscope and the effects of skin barrier damages were examined according to time. Three mins and 1hr after acetone damage, the gradations of epidermis and hair follicle showed more radiant and disappeared after 48 hrs. On the contrary, 3mins and 1hr after tape stripping damage, the gradations showed more radiant than those of acetone damage, and these gradations were stabilized after 48 hrs. The method we presented here could show the visual image of the calcium ions in frozen tissue without further preparation, and it might be useful to investigate the role of calcium ion in the canine epidermal barrier recovery, however, it might be need further methodological improvement to get accurate quantitative information.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.1
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• pp.6-13
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• 2012

HVOF thermal spray coating of 80%WC-CoFe powder is one of the most promising candidate for the replacement of the traditional hard chrome plating and hard ceramics coating because of the environmental problem of the very toxic $Cr^{6+}$ known as carcinogen by chrome plating and the brittleness of ceramics coatings. 80%WC-CoFe powder was coated by HVOF thermal spraying for the study of durability improvement of the high speed spindle such as air bearing spindle. The coating procedure was designed by the Taguchi program, including 4 parameters of hydrogen and oxygen flow rates, powder feed rate and spray distance. The surface properties of the 80%WC-CoFe powder coating were investigated roughness, hardness and porosity. The optimal condition for thermal spray has been ensured by the relationship between the spary parameters and the hardness of the coatings. The optimal coating process obtained by Taguchi program is the process of oxygen flow rate 34 FRM, hydrogen flow rate 57 FRM, powder feed rate 35 g/min and spray distance 8 inch. The coating cross-sectional structure was observed scanning electron microscope before chemical etching. Estimation of coating porosity was performed using metallugical image analysis. The Friction and wear behaviors of HVOF WC-CoFe coating prepared by OCP are investigated by reciprocating sliding wear test at $25^{\circ}C$ and $450^{\circ}C$. Friction coefficients (FC) of coating decreases as sliding surface temperature increases from $25^{\circ}C$ to $450^{\circ}C$.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.733-741
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• 1996

In this study MeV Si self ion implantations were done to reveal the intrinsic behavior of defect formation by excluding the possibility of chemical interactions between substrate atoms and dopant ones. Self implantations were conducted using Tandem Accelerator with energy ranges from 1 to 3 MeV. Defect formation by high energy ion implantation has a significant characteristics in that the lattice damage is concentrated near Rp and isolated from the surface. In order to investigate the energy dependence on defect formation, implantation energies were varied from 1 to 3 MeV under a constant dose of $1{\times}10^{15}/cm^2$. RBS channe!ed spectra showed that the depth at which as-implanted damaged layer formed increases as energy increases and that near surface region maintains better crystallinity as energy increases. Cross sectional TEM results agree well with RBS ones. In a TEM image as-implanted damaged layer appears as a dark band, where secondary defects are formed upon annealing. In the case of 2 MeV $Si^+$ self implantation a critical dose for the secondary defect formation was found to be between $3{\times}10^{14}/cm^24$ and $5{\times}10^{14}/cm^2$. Upon annealing the upper layer of the dark band was removed while the bottom part of the dark band did not move. The observed defect behavior by TEM was interpreted by Monte Carlo computer simulations using TRIM-code. SIMS analyses indicated that the secondary defect formed after annealing gettered oxygen impurities existed in silicon.