• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1744-1748
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• 2004

It is important to measure precisely the size and velocity of micro-bubbles used in various field. The synchrotron X-ray micro-imaging technique was employed to measure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Phase contrast images were obtained at interfaces of micro-bubbles between water and air due to their different refractive indices. The X-ray micro-imaging technique was found to measure an optical fiber with an accuracy of 0.2%. Micro-bubbles of $10{\sim}60{\mu}m$ diameter moving upward in an opaque tube (${\phi}=2.7mm$) were tested to measure bubble size and up-rising velocity. For DI water, the measured velocity of micro-bubbles is nearly proportional to the square of bubble size, agreed well with the theoretical result. In addition, the synchrotron X-ray micro-imaging technique can measure accurately the size and velocity of several overlapped micro-bubbles.

• Journal of Veterinary Clinics
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• v.38 no.4
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• pp.174-178
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• 2021

A nine-year-old neutered male cat was presented with chronic cough and vomiting. Thoracic radiography showed regions of fatty opacity in the right caudoventral region. On positive contrast celiography, contrast agent did not move into thoracic cavity. Computed tomography revealed 7-mm diameter of defect at the right diaphragmatic crus and a 2-mm diameter defect at the left ventral diaphragmatic crus. Through the right diaphragmatic defect omental herniation was confirmed by the presence of contrast enhanced omental vessel running across the diaphragm. On exploratory thoracotomy, the omentum protruded into the thorax through the right diaphragmatic defect, and it contained a yellowish lipomatous mass. The protruded omentum containing a mass in the thorax was removed, and the right diaphragmatic defect was closed. Histopathologic examination revealed that the protruded omentum showed normal omental structure and the adipose mass showed lipoma surrounded by fibrous tissue. In conclusion, a thorough examination is necessary to confirm the origin of the mass located near the diaphragm.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.35-40
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• 2002

Purpose : To evaluate the NMR relaxation properties and imaging characteristics of tissue-specificity for a newly developed macromolecular MR agent. Materials and methods : Phthalocyanine (PC) was chelated with paramagnetic ion, Mn.2.01g (5.2 mmol) of Phthalocyanine was mixed with 0.37g (1.4 mmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography (CHC13/CH3OH 98/2 v/v, Rf, 0.76) to obtain 1.04g (46%) of MnPC (molecular weight= 2000d). The $T1}T2$ relaxivity of MnPC was measured in 1.5T(64 MHz) MR using 0.1 mM MnPC. The MR image characteristics of MnPC was evaluated using spin-echo (TR/TE=500/14 msec) and gradient-echo (FLASH) (TR/TE=80/4 msec, flip angle=60) techniques in 1.57 MR scanner. The images of rabbit liver were obtained every 10 minutes up to 4 hours. To study the effect of concentration on image, 20 mM, 50 mM, 100 mM of MnPC were tested. Results : The relaxivities of MnPC at 1.5T(64MHz) were Rl=7.28 $mM^{-1}S^{-1},{\;}R2=55.56mM^{-1}S^{-1}$. Compared to the values of Gd-DTPA (Rl[=4.8 $mM^{-1}S^{-1})$], R2[=5.2 $mM^{-1}S^{-1}])$]), both T1/T2 relaxivities of MnPC were higher than those of Gd-DTPA. For both of SE and FLASH techniques, the contrast enhancement reached maximum at 10 minutes after bolus injection and the enhancement continued for more than 2 hours. When compared with small molecular weight liver agents such as Gd-EOB-DTPA, Gd-BOPTA and MnDPDP, MnPC was characterized by more prolonged enhancement time. The time course of MR images also revealed biliary excretion of MnPC. Conclusion : We developed a new macromolecular MR agent, MnPC. The relaxivities of MnPC were higher than those of small molecular weight Gd-chelate. Hepatic uptake and biliary excretion of MnPC suggests that this agent is a new liver-specific MR agent.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.143-148
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• 2011

The purpose of this study was to examine the usefulness of SPIO contrast agent in Magnetic Resonance Cholangiopancreatography (MRCP) by performing a quantitative comparative analysis in patients undergoing MRCP for gallbladder stones with and without oral injection of SPIO (Superparamagnetic iron oxide) contrast agent. The subjects were 36 patients undergoing MRCP for suspected gallbladder stones between January 2009 and February 2010 and they were divided into halves to compare the two groups of with and without SPIO agent. For each subject in both the injected and non-injected group, T2-weighted images on a 1.5T MR scanner were obtained, using both the breath-holding and respiratory-triggered methods, respectively. The following regions were measured; for breath-hold T2-weighted images, the measurement regions were located at the central part of the gallbladder, and the areas 15 mm away from its center, toward the front and back, respectively, which were chosen to include surrounding tissues, while for respiratory-triggered T2-weighted images, at the central part of the gallbladder, and segment 5 and 6 of liver. In a quantitative analysis, average signal to noise ratio (SNR) in each of regions of interest (ROI) for each group were calculated and then average contrast to noise ratio (CNR) in each of ROI were obtained by using the SNR in the gallbladder as the basis to compare and analyze the values between the two groups. The CNR were higher for the injected group in those regions.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.323-329
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• 2020

The purpose of this study is to investigate the effect of radiation shielding on the thyroid organ dose and image quality during Chest PA examination using automatic exposure control system. This study was conducted in the patient posture and examination conditions such as Chest PA using human model phantom. An experiment without shielding was set as a control group (non) and the cases of using paper coated with a contrast agent (contrast) and bismuth (bismuth) were used as experimental groups. Compared to non-shielded(non), the dose at bismuth increased about 7% in C(cervical vertebrae)5 and C6 and 14% in C7 and contrast showed dose increases of about 17 to 19% in C5 and C6 and about 21% in C7. As a result of the image quality comparison, when measured in the center of the cervical vertebrae, both SNR and CNR in bismuth increased about 40% higher than non, and contrast showed about 8 to 9% improvement. Compared with soft tissues of the cervix, bismuth reduced SNR by about 15% and CNR by about 13%, in contrast, SNR decreased by 11%, and CNR decreased by about 10%. In the Chest PA using AEC, the method of using the shield in front of the collimator has the advantage to observe the anatomical structure of the neck area well compared to the method using the lead. However, the dose at the neck can be increased by 7-21% depending on shielding materials.

• Culinary science and hospitality research
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• v.13 no.3
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• pp.44-53
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• 2007

This study investigated the utilization of pumpkin cream soup mixture of pumpkin P1(sweet pumpkin 25%, pumpkin 75%), and S1(rice flour 100%) and S3(rice powder 50%, glutinous rice powder 50%) as thickening agents showed highest preference for pumpkin cream soup. Rice powder was used in pumpkin cream soup as a thickening agent. Hunter's color marked the lowest value in using group of flour roux, in contrast with the highest value in using glutinous rice powder roux. The results of viscosity were diverse according to the condition of relationships between the percentage of contents flour, rice and glutinous rice control. For the sensory evaluation, parameters such as appearance, color, viscosity and savory taste increased significantly from the control at glutinous rice roux, and overall acceptability marked the lowest result in flour roux control.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.102-107
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• 2017

The dependence of the IR optical properties of PMMA/$Al_2O_3$ nanocomposite on the alumina content was investigated in the wavelength range of $3500-2800cm^{-1}$. The samples were prepared via emulsion polymerization technique using oleic acid as a coupling agent. Grafting density calculations were carried out by means of elemental analysis CHN to yield the best coupling agent content. FTIR analysis confirmed the existence of a chemical bond between aluminum oxide and oleic acid. The outcomes of XRD analyses showed the presence of cubic gamma aluminum oxide in the nanocomposite, in contrast to the amorphous nature of PMMA. TEM images showed the core-shell morphology of the particles other than pristine PMMA. Optical constants of the nanocomposite were calculated based on FTIR spectra and the Kramers-Kronig equations. The presence of nano alumina modified some of the optical indexes in IR region.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.445-451
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• 2021

Salicylamide, a non-steroidal anti-inflammatory drug (NSAID), is used as an analgesic and antipyretic agent. We have previously shown that several NSAIDs have anti-melanogenic properties in B16F1 melanoma cells. In contrast, we have found that salicylamide enhances melanin contents in B16F1 melanoma cells; however, the underlying mechanism is not known. Therefore, we investigated the mechanism through which salicylamide stimulates melanogenesis. Interestingly, salicylamide enhanced diphenolase activity in a cell-free assay. Western blotting and real-time RT-PCR revealed that salicylamide increased tyrosinase expression via transcriptional activation of the Mitf gene. Together, our results indicate that salicylamide could be used as an anti-hypopigmentation agent for skin and/or hair.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.1
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• pp.33-39
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• 2023

In this study, the effect of mixing condition of raw material powders possessing various particle size and particle size distribution on thermite reaction efficiency was investigated. When fine raw powders are used, rather the reaction yield tends to decrease due to agglomeration. In contrast, coarse raw powders make deteriorate the contact area between raw material powders containing Al reducing agent. To ensure the optimal thermite reaction efficiency, it is required to optimize a mixture condition of raw material powders prior to thermite reaction. From the current experiment, the maximum thermite reaction efficiency is 77%, which came from Nb₂O₅ + NiO +Al mixtures with size distribution from 9.25 to 22.63 ㎛.