• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.6
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• pp.659-670
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• 2017

Oxidative stress and inflammation are key factors responsible for progression of liver injury. A variety of functions of oyster hydrolysate (OH) are affected by their antioxidant and anti-inflammatory activities. However, little is known regarding the effects of OH on a liver injury model. This study was performed to evaluate the effects of OH on acute liver injury induced by lipopolysaccharide/D-galactosamine (LPS/D-GalN) in mice. Experimental groups were divided into six groups as follows (each group, n=10): control (saline), LPS/D-GalN, LPS/D-GalN+OH (100 mg/kg), LPS/D-GalN+OH (200 mg/kg), LPS/D-GalN+OH (400 mg/kg), and LPS/D-GalN+silymarin (25 mg/kg, positive control). The experimental acute liver injury model was induced with LPS ($1{\mu}g/kg$) and D-GalN (400 mg/kg). We first analyzed antioxidant and anti-inflammatory activities in OH. OH showed high DPPH and ABTS radical scavenging activities and reduced ROS generation in Chang cells in a dose-dependent manner. In addition, OH showed anti-inflammatory activities, such as inhibition of cyclooxygenase-2 and 5-lipooxygenase. Treatment with OH down-regulated tumor necrosis factor $(TNF)-{\alpha}$, interleukin (IL)-6, and $IL-1{\alpha}$ expression levels in LPS-stimulated RAW264.7 cells. OH significantly reduced LPS/D-GalN-induced increases in the concentrations of alanine transaminase and aspartate aminotransferase in serum. In the LPS/D-GalN group, liver tissues exhibited apoptosis of hepatocytes with hemorrhages. These pathological alterations were ameliorated by OH treatment. Consistently, hepatic catalase activity was low in the LPS/D-GalN group compared to the control group, and catalase activity was significantly restored by OH treatment (P<0.05). Furthermore, OH markedly reduced the LPS/D-GalN-induced increase in $TNF-{\alpha}$, $IL-1{\beta}$, and IL-6 levels in liver tissue. Taken together, these results show that OH has hepatoprotective effects on LPS/D-GalN-induced acute liver injury via inhibition of oxidative stress and inflammation, suggesting that OH could be used as a health functional food and potential therapeutic agent for acute liver injury.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.335-341
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• 2017

Cyclotron is a device that accelerates positrons or neutrons, and is used as a facility for making radioactive drugs having short half-lives. Such radioactive drugs are used for positron emission tomography (PET), which is a medical apparatus. In order to make radioactive drugs from a cyclotron, a nuclear reaction must occur between accelerated positrons and a target. After the reaction, unncessary neutrons are produced. In the present study, radioactivation generated from the collisions between the concrete shielding wall and the positrons and neutrons produced from the cyclotron is investigated. We tracked radioactivated radioactive isotopes by conducting experiments using FLUKA, a type of Monte Carlo simulation. The properties of the concrete shielding wall were comparatively analyzed using materials containing impurities at ppm level and materials that do not contain impurities. The generated radioactivated nuclear species were comparatively analyzed based on the exposure dose affecting human body as a criterion, through RESRAD-Build. The results of experiments showed that the material containing impurities produced a total of 14 radioactive isotopes, and $^{60}Co$(72.50%), $^{134}Cs$(16.75%), $^{54}Mn$(5.60%), $^{152}Eu$(4.08%), $^{154}Eu$(1.07%) accounted for 99.9% of the total dose according to the analysis having the exposure dose affecting human body as criterion. The $^{60}Co$ nuclear species showed the greatest risk of radiation exposure. The material that did not contain impurities produced a total of five nuclear species. Among the five nuclear species, 54Mn accounted for 99.9% of the exposure dose. There is a possibility that Cobalt can be generated by inducive nuclear reaction of positrons through the radioactivation process of $^{56}Fe$ instead of impurities. However, there was no radioactivation because only few positrons reached the concrete wall. The results of comparative analysis on exposure dose with respect to the presence of impurities indicated that the presence of impurities caused approximately 98% higher exposure dose. From this result, the main cause of radioactivation was identified as the small ppm-level amount of impurities.

• Radiation Oncology Journal
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• v.29 no.3
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• pp.164-173
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• 2011

Purpose: This research aimed to analyze the patterns of co-authorship network among the Korean radiation oncologists and to identify attributing factors for the formation of networks. Materials and Methods: A total of 1,447 articles including contents of ‘Radiation Oncology' and 'Therapeutic Radiology' were searched from the KoreaMed database. The co-authorship was assorted by the author's full name, affiliation and specialties. UCINET 6.0 was used to fi gure out the author's network centrality and the cluster analysis, and KeyPlayer 1.44 program was used to get a result of key player index. Sociogram was analyzed with the Netdraw 2.090. The statistical comparison was performed by a t-test and ANOVA using SPSS 16.0 with p-value < 0.05 as the significant value. Results: The number of articles written by a radiation oncologist as the first author was 1,025 out of 1,447. The pattern of coauthorship was classified into five groups. For articles of which the first author was a radiation oncologist, the number of singleauthor articles (type-A) was 81; single-institution articles (type-B) was 687; and multiple-author articles (type-C) was 257. For the articles which radiation oncologists participated in as a co-author, the number of single-institution articles (type-D) was 280 while multiple-institution articles (type-E) were 142. There were 8,895 authors from 1,366 co-authored articles, thus the average number of authors per article was 6.51. It was 5.73 for type-B, 6.44 for type-C, 7.90 for type-D, and 7.67 for type-E (p = 0.000) in the average number of authors per article. The number of authors for articles from the hospitals published more than 100 articles was 7.23 while form others was 5.94 (p = 0.005). Its number was 5.94 and 7.16 for the articles published before and after 2001 (p = 0.000). The articles written by a radiation oncologist as the first author had 5.92 authors while others for 7.82 (p = 0.025). Its number was 5.57 and 7.71 for the Journal of the Korean Society for Therapeutic Radiology and Oncology and others (p = 0.000), respectively. Among the analysis, a significant difference in the average number of author per article was indicated. The out-degree centrality of network among authors was 4.26% (2.03-7.09%) while in-degree centrality was 1.31% (0.53-2.84%). The three significant nodes were classified and listed as following: Choi, Eun Kyung for 1991-1995, Kim, Dae Young for 1998-2001, Park, Won and Lee, Sang Wook for 2003-2010. Choi, Eun Kyung and Kim, Dae Young appeared in two cases, and ranked as the highest degree in centrality. In the key player analysis, Choi, Eun Kyung and Lee, Sang Wook appeared in two cases, and ranked as the highest. From the cluster analysis, Sungkyunkwan University, Seoul National University and Yonsei University revealed as the three large clusters when Ulsan University, Chonnam National University, and Korea Institute of Radiological & Medical Science as the medium clusters. Conclusion: The Korean radiation oncologist's society shows a closed network with numerous relationships among the particular clusters, and the result indicates it is different from other institutions in the pattern of co-authorship formation of the major hospitals.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.927-933
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• 2021

The purpose of this study was to compare and analyze the differences in scan time, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the third lumbar vertebral region including the back fat, spinal cord, and cerebrospinal fluid using the mDixon, T2 TSE, and T2 spectral pre-saturation with inversion-recovery (SPIR) techniques. With the factors affecting the SNR fixed, the lumbar sagittal plane images of 30 adults were compared on mDixon, T2 TSE, and T2 SPIR imaging tests. The test times for mDixon, T2 TSE, and T2 SPIR were 115 seconds, 60 seconds, and 60 seconds, respectively. The mDixon T2 images showed higher SNR than the T2 TSE images at the third lumbar vertebral region (p<0.05), lower SNR in the back fat and cerebrospinal fluid (p<0.05) areas, and comparable SNR in the spinal cord (p>0.05). The CNR between the third lumbar vertebral area and back fat was higher in the mDixon T2 images, and the CNR of the cerebrospinal fluid and spinal cord images was higher in the T2 TSE images (p<0.05). The mDixon T2 FS images CNR was lower for the 3rd lumbar vertebral body region and back fat than the T2 SPIR images, and higher for the spinal cord and cerebrospinal fluid images (p<0.05). The CNR between the third lumbar body and back fat areas was higher in the mDixon T2 FS images (p<0.05), and there was no difference in the CNR in the images of the cerebrospinal fluid and the spinal cord (p>0.05). It is difficult to determine whether the mDixon technique is superior to the conventional T2 TSE and T2 SPIR techniques in terms of test time, SNR, and CNR. This study was confined to patients with simple lower back pain and was limited by controlled experimental conditions. Studies using clinically applied protocols are warranted in the future.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.171-176
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• 2009

Purpose : To investigate the effect of coating material in RF coil, which is one of main parts in MRI machine, on the Q-factor and SNR(signal-to-noise ratio) in MR images. Materials and Methods : RF coils with inner diameter of 1.7 mm were made by using copper wires coated with polyester, polyurethane, polyimide, polyamideimide, and polyester-imide, and by using copper wires in which coating materials had been removed. Q-factors of the RF coils were measured by network analyzer, and SNR values in the spin-echo MR images obtained by 600 MHz (14.1 T, Bruker DMX600) micro-imaging system for the coated and uncoated cases. Results : The measured SNRs were almost same for the RF coils with coat-removed copper wires, however SNRs and Q-factors were different for the coated cases depending on the coating material. They were maximized in the polyurethane-coated case in which the SNR was > 30% greater than polyester-coated case. Conclusion : We made solenoid-type RF coils which were easily used for MR micro-imaging in Bruker MRI probe. There was a significant coating-material dependence in the measured Q values and SNRs for the home-made RF coils. The study demonstrated that the choice of coating material of RF coil may be a critical factor in the MRI sensitivity based on SNR value.

• Investigative Magnetic Resonance Imaging
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• v.14 no.1
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• pp.10-20
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• 2010

Purpose : Recently, the Recon Challenge at the 2009 ISMRM workshop on Data Sampling and Image Reconstruction at Sedona, Arizona was held to evaluate feasibility of highly accelerated acquisition of time resolved contrast enhanced MR angiography. This paper provides the step-by-step description of the winning results of k-t FOCUSS in this competition. Materials and Methods : In previous works, we proved that k-t FOCUSS algorithm successfully solves the compressed sensing problem even for less sparse cardiac cine applications. Therefore, using k-t FOCUSS, very accurate time resolved contrast enhanced MR angiography can be reconstructed. Accelerated radial trajectory data were synthetized from X-ray cerebral angiography images and provided by the organizing committee, and radiologists double blindly evaluated each reconstruction result with respect to the ground-truth data. Results : The reconstructed results at various acceleration factors demonstrate that each components of compressed sensing, such as sparsifying transform and incoherent sampling patterns, etc can have profound effects on the final reconstruction results. Conclusion : From reconstructed results, we see that the compressed sensing dynamic MR imaging algorithm, k-t FOCUSS enables high resolution time resolved contrast enhanced MR angiography.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.589-594
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• 2017

The objective of this study was to evaluate the enhancement effects of the quantum denoising system (QDS) on brain CT images. This retrospective study was conducted with 45 adults who visited G Radiology located in Gyungbuk for having brain CT tests between Jul 2017 and Oct 2017 after receiving consents. Subjects were divided into a control group (A group; no QDS(-) application during the brain CT test) and a treatment group (B Group; QDS(+) application during the brain CT test). The following conclusions were obtained from the study. The noise values at the Pons part and the Vermis part were significantly (p<0.05) lower in B Group ($Pons=5.41{\pm}1.05HU$; $Vermis=5.28{\pm}0.73HU$) than A Group ($Pons=6.92{\pm}0.98HU$; Vermis=6.72). The SNR values at the Pons part and the Vermis part were significantly (p<0.05) higher in B Group ($Pons=7.28{\pm}2.56$; $Vermis=8.63{\pm}3.04$) than A Group ($Pons=5.21{\pm}1.28$; $Vermis=6.23{\pm}1.49$). In conclusion, the results of this study suggested that the application of QDS to the brain CT test would enhance the signal to noise ratio (SNR) and the contrast to noise ratio (CNR) to provide an image more appropriate for diagnosis.

• Journal of radiological science and technology
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• v.44 no.2
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• pp.101-107
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• 2021

The purpose of this study was to evaluate optimal CT scan parameters to minimize patient dose to the irradiation and maintain satisfactory image quality in low-dose chest computed tomography (CT) scans. In a chest anthropomorphic phantom, chest CT scans were performed at different kVp and mA within reference of 3.4mGy in volume CT Dose Index (CTDI_vol). The following quantitative parameters had been statistically evaluated: image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM). Nine radiographers conducted the blind test to select the optimal kVp-mA combination. Results indicated that the kVp-mA combination of 80kVp-90mA, 100kVp-50mA, 120kVp-30mA and 140kVp-30mA were obtained high SNR and CNR. The 120kVp-30mA combination offered good compromise in the FOM, which showed the quality and dose performance. In the blind test, an image of 80kVp-90mA obtained a high score with 4.7 points, and 120kVp-10mA or 140kVp-10mA with a low tube current were observed severe noise and poor image quality, thus resulting in decreased diagnostic accuracy. On the other hand, in the combination of high kVp and high mA(140kVp-90mA), the image quality was improved, but the radiation dose was also increased. the FOM value of 140kVp-90mA was lower than 120kVp-30mA. The application of appropriate scan parameters in low-dose chest CT scans produced satisfactory results in dose and image quality for the accuracy of the clinical diagnosis.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.239-246
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• 2014

Filter absorbs low-energy X-ray to increase the average energy and reduces patient exposure dose. This study investigates if the materials of Mo and W could be used for the digital imaging device CR by conducting image assessment and dose measurement of SNR, FOM and histogram. In addition, measurement of beam quality was conducted depending on the material of the filter, and at the same time, a proper combination of filters was examined depending on the change in tube voltage (kVp). In regard to entrance skin dose, Mo filter showed the dose reduction by 42~56%, compared to Cu filter. Moreover, Mo filter showed higher transmission dose by around 1.5 times than that of Cu filter. In image assessment, it was found that W was unsuitable to be used as a filter, whereas Mo could be used as a filter to reduce dose without decline in image quality at the tube voltage of 80 kVp or higher. As tube voltage increased, 2.0 mm Al+0.1 mm Mo almost had a similar histogram width to that of 2.0 mm Al+0.2 mm Cu. Therefore, Mo filter can be used at relatively high tube voltage of 80 kVp, 100 kVp and 120 kVp. The SNR of 2.0 mm Al+0.1 mm Mo did not show any significant difference from those of 2.0 mm Al+0.2 mm Cu and 2.0 mm Al+0.1 mm Cu. As a result, if Mo filter is used to replace Cu filter in general radiography, where 80 kVp or higher is used for digital radiation image, patient exposure dose can be reduced significantly without decline in image quality, compared to Cu filter. Therefore, it is believed that Mo filter can be applied to chest X-ray and high tube voltage X-ray in actual clinical practice.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.318-333
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• 2023

The purpose of this study is to analyze changes in dental trauma in children under the age of 12 during the period of Coronavirus Disease 2019 (COVID-19). March 2020, when COVID-19 was officially declared a pandemic by the World Health Organization, was set as the starting point for COVID-19. From March 2018 to February 2020, subjects in the pre-COVID-19 period were classified as the Pre-COVID-19 group, and from March 2020 to March 2022, subjects in the post-COVID-19 period were classified as the COVID-19 group. Information related to trauma was collected through electronic medical records. The number of trauma patients before and after the outbreak of COVID-19 decreased significantly. During the COVID-19 period, there was no significant difference in the male-female ratio or the distribution order of age groups. In the COVID-19 group of permanent teeth, the ratio of trauma caused by personal mobility was higher than trauma caused by sports. In the COVID-19 group of permanent teeth, the ratio of crown fracture with pulp involvement was significantly higher than the ratio of crown fracture without pulp involvement. Changes in trauma patterns caused by COVID-19 were observed more clearly in school-aged children than in preschool children. In a pandemic situation such as COVID-19, it is expected to be used as a good educational basis for knowing that frequent diagnoses can change due to changes in the environment.