• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1822-1827
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• 2019

Mechanical responses and failure behaviors of advanced C/C composite tube are very important for structural component design in nuclear reactor. In this study, an experimental investigation was conducted to study mechanical properties of C/C composite tube. Quasi-static compression loading was applied to a type of advanced composite tube to determine the response of the quasi-static load displacement curve during progressive damage. Acoustic emissions (AE) signals were captured and analyzed to characterize the crack formation and crack development. In addition, the crack propagation of the specimens was monitored by imaging technique and failure mode of the specimen was analyzed. FEM is appled to simulate the stress distribution. Results show that advanced C/C composite tube exhibits considerable energy absorption capability and stability in load-carrying capacity.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.6
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• pp.439-446
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• 2022

The antitumoral effects of valdecoxib (Val), an United States Food and Drug Administration-approved anti-inflammatory drug that was withdrawn due to the side effects of increased risk of cardiovascular adverse events, were investigated in hypopharyngeal squamous cell carcinoma cells by performing a cell viability assay, transwell assay, immunofluorescence imaging, and Western blotting. Val markedly inhibited cell viability with an IC50 of 67.3 µM after 48 h of treatment, and also downregulated cell cycle proteins such as Cdks and their regulatory cyclin units. Cell migration and invasion were severely suppressed by inhibiting integrin α4/FAK expression. In addition, Val activated the cell cycle checkpoint CHK2 in response to excessive DNA damage, which led to the activation of caspase-3/9 and induced caspase-dependent apoptosis. Furthermore, the signaling cascades of the PI3K/AKT/mTOR and mitogen-activated protein kinase pathways were significantly inhibited by Val treatment. Taken together, our results indicate that Val can be used for the treatment of hypopharyngeal squamous cell carcinoma.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.147-148
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• 2020

In case of high temperature damage such as fire, the durability of concrete is reduced due to the collapse of internal pore tissue. Therefore, in this paper, we are going to analyze the pore structure of cement paste hardening agent using MIP analysis and build up 3D data produced using X-ray CT tomography. The test specimen is made of cement paste from W/C 0.4. As the temperature of heating increased, the amount of air gap and the diameter of air gap in cement paste increased. It is judged that the air gap structure inside cement collapsed due to the evaporation of the hydrate, gel count, capillary water, etc. inside the cement due to the high temperature.

• Journal of Conservation Science
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• v.32 no.2
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• pp.235-247
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• 2016

Conventional imaging techniques such as ultraviolet, infrared, and X-ray are used mainly to diagnose the damaged parts of the painted cultural assets in Korea. These techniques, however, have limits in diagnosing damages of interlayer parts. We have performed and extensive study on the applicability of Terahertz(THz) analysis technique, introduced recently to this field of study on cultural properties in Korea, to diagnose painted cultural assets. The specimens, produced to imitate the damage types of Korean painted properties, were analyzed over their painting, supporting, and backing layers by terahertz pulse imaging technique. The analyzed results provided information about the cracks, the separated areas, and the separated distances between layers on the specimens. Our research, then, was extended to real painted cultural remains, Birojana Sam-shin Gwebul-do at Bongseon Temple in Namyang-ju, Korea National Treasure Number 1792, through which we have obtained 3D information about the extent and pattern of damages to the asset. These results demonstrate that terahertz 3D imaging technique has the capability of noncontact 3D diagnosis on painted cultural properties.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.87-102
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• 2005

In the congested urban areas, tunnelling close to existing structures or services often occurs due to the lack of surface space so that tunnelling-induced ground movements may cause a serious damage to the adjacent structures. This study focused on the two dimensional laboratory model pile-soil-tunnelling interaction tests using a close range photogrammetric technique. Testing equipments and procedures were Introduced, particularly features of aluminium rods regarded as the frictional granular material. The experimental result showed that the photo imaging process by the VMS and EngVis programs proved to be a useful tool in measuring the pile tip movements during the tunnelling. Consequently, the normalised pile tip movement data for the influence zones can be generated by the laboratory model tests using the Photogrammetric technique. This study presents influence zones associated with the normalized pile tip settlements due to tunnelling in the cohesionless material. The influence zones were Identified by both a laboratory model test and a numerical analysis. The normalized pile tip movements from the model test were in good agreement with the numerical analysis result. The influence zones proposed in this study could be used to decide the reasonable location of tunnel construction in the planning stage. However, the scale of model pile and model tunnel sizes must be carefully adjusted as real ones for practical application considering the ground conditions at a given site.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.830-843
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• 2019

Objective: To examine the potential of intravoxel incoherent motion (IVIM) and blood oxygen level-dependent (BOLD) magnetic resonance imaging for detecting renal changes after iodinated contrast-induced acute kidney injury (CI-AKI) development in a diabetic rabbit model. Materials and Methods: Sixty-two rabbits were randomized into 2 groups: diabetic rabbits with the contrast agent (DCA) and healthy rabbits with the contrast agent (NCA). In each group, 6 rabbits underwent IVIM and BOLD imaging at 1 hour, 1 day, 2 days, 3 days, and 4 days after an iohexol injection while 5 rabbits were selected to undergo blood and histological examinations at these specific time points. Iohexol was administrated at a dose of 2.5 g I/kg of body weight. Further, the apparent transverse relaxation rate (R2^*), average pure molecular diffusion coefficient (D), pseudo-diffusion coefficient (D^*), perfusion fraction (f) were calculated. Results: The D and f values of the renal cortex (CO) and outer medulla (OM) were significantly decreased compared to baseline values in the 2 groups 1 day after the iohexol injection (p < 0.05). A marked reduction in the D^* values for both the CO and OM was also observed after 1 hour in each group (p < 0.05). In the OM, a persistent elevation of the R2^* was detected for 4 days in the DCA group (p < 0.05). Histopathological changes were prominent, and the pathological features of CI-AKI aggravated in the DCA group until day 4. The D, f, and R2^* values significantly correlated with the histological damage scores, hypoxia-inducible transcription factor-1α expression scores, and serum creatinine levels. Conclusion: A combination of IVIM and BOLD imaging may serve as a noninvasive method for detecting and monitoring CI-AKI in the early stages in the diabetic kidney.

• The Korean Journal of Nuclear Medicine
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• v.39 no.3
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• pp.200-208
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• 2005

Purpose: Tc-99m labeled diethylenetriaminepentaacctic acid (DTPA)-coupled galactosylated human serum albumin (GSA) is a currently used imaging agent for asialoglycoprotein receptor (ASGPR) of the liver, but, it has several shortcomings. Recently a new ASGPR imaging agent, $^{99m}Tc$-lactosylated human serum albumin (LSA), with simple labeling procedure, high labeling efficiency, high stability was developed. In order to assess the feasibility of the $^{99m}Tc$-LSA as a ASGPR imaging radiopharmaceuticals, we performed biodistribution study of the tracer in liver injured mice model and the results were compared with histolgic data. Materals and Methods: To induce hepatic damage in ICR mice, diethylnitrosamine (DEN) ($60mg/kg/week{\times}5time$, low dose or $180mg/kg/week{\times}2times$, high dose) and thioacetamide (TAA) ($50mg/kg{\times}1time$) were administrated intraperitoneally. Degree of liver damage was evaluated by tissue hematoxilin-eosin stain, and expression of asialoglycoprotein receptor (ASGPR) was assessed by immunohistochemistry using ASGPR antibody. $^{99m}Tc$-LSA was intravenously administrated via tail vein in DEN or TAA treated mice, and biodistribution study of the tracer was also performed. Results: DEN treated mice showed ballooning of hepatocyte and inflammatory cell infiltration in low dose group and severe hapatocyte necrosis in high dose group, and low dose group showed higher ASGPR staining than control mice in immunohistochemical staining. TAA treated mice showed severe hepatic necrosis. $^{99m}Tc$-LSA Biodistribution study showed that mice with hepatic necrosis induced by high dose DEN or TAA revealed higher blood activity and lower liver activity than control mice, due to slow clearance of the tracer by the liver. The degree of liver uptake was inversely correlated with the degree of histologic liver damage. But low dose DEN treated mice with mild hepatic injury showed normal blood clearance and hepatic activity, partly due to overexpression of ASGPR in mice with mild degree hepatic injury. Conclusion: Liver uptake of $^{99m}Tc$-LSA was inversely correlated with degree of histologic hepatic injury in DEN and TAA treated mice. These results support that $^{99m}Tc$-LSA can be used to evaluate the liver status in liver disease patients.

• Journal of Ginseng Research
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• v.46 no.4
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• pp.515-525
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• 2022

Background: The incidence of ischemic cerebrovascular disease is increasing in recent years and has been one of the leading causes of neurological dysfunction and death. Ginsenoside Rg1 has been found to protect against neuronal damage in many neurodegenerative diseases. However, the effect and mechanism by which Rg1 protects against cerebral ischemia-reperfusion injury (CIRI) are not fully understood. Here, we report the neuroprotective effects of Rg1 treatment on CIRI and its possible mechanisms in mice. Methods: A bilateral common carotid artery ligation was used to establish a chronic CIRI model in mice. HT22 cells were treated with Rg1 after OGD/R to study its effect on [Ca²⁺]_i. The open-field test and poleclimbing experiment were used to detect behavioral injury. The laser speckle blood flowmeter was used to measure brain blood flow. The Nissl and H&E staining were used to examine the neuronal damage. The Western blotting was used to examine MAP2, PSD95, Tau, p-Tau, NOX2, PLC, p-PLC, CN, NFAT1, and NLRP1 expression. Calcium imaging was used to test the level of [Ca²⁺]_i. Results: Rg1 treatment significantly improved cerebral blood flow, locomotion, and limb coordination, reduced ROS production, increased MAP2 and PSD95 expression, and decreased p-Tau, NOX2, p-PLC, CN, NFAT1, and NLRP1 expression. Calcium imaging results showed that Rg1 could inhibit calcium overload and resist the imbalance of calcium homeostasis after OGD/R in HT22 cells. Conclusion: Rg1 plays a neuroprotective role in attenuating CIRI by inhibiting oxidative stress, calcium overload, and neuroinflammation.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.575-583
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• 2022

Magnetic resonance diffusion tensor imaging (DTI) has revealed the disruption of brain white matter microstructure in normal aging and alcoholism undetectable with conventional structural MR imaging. we plan to analyze the FA measurements of the ROI of dangerous drinkers selected from Alcohol Use Disorders Identification Test (AUDIT) and Tract-Based Spatial Statics (TBSS) tool was used to extract FA values in the ROI from the image acquired through the pre-processing process. TBSS has a higher sensitivity of the FA value and MD value in the white matter than the brain gray matter, and has the advantage of quantitatively deriving the unlimited degree of brain nerve fibers, and more specialized in the brain white matter. We plan to analyze the fractional anisotropy (FA) measurement value for damage by selecting the center of the anatomical structure of the white matter region of the brain with high anisotropy among the brain neural networks that are particularly vulnerable to alcohol as the region of interest (ROI). In this study, we expected that alcohol causes damage to the brain white matter microstructure from FA value in various areas including both Choroid plexus. Especially, In the case of the moderate drunker, the mean value of FA in Lt, Rt. Choroid plexus was 0.2831 and 0.2872, whereas, in the case of the severe drunker, the mean value of FA was 0.1972 and 0.1936. We found that the higher the score on the AUDIT scale, the lower the FA value in ROI region of the brain white matter. Using the AUDIT scale, the guideline for the FA value of DTI can be presented, and it is possible to select a significant number of potentially severe drinkers. In other words, AUDIT was proved as useful tool in screening and discrimination of severe drunker through DTI.

• Imaging Science in Dentistry
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• v.50 no.1
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• pp.9-14
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• 2020

Purpose: The purpose of this study was to evaluate vertical bone loss and alveolar bone thickness in the maxillary and mandibular incisors of patients with skeletal class III malocclusion. This study also aimed to evaluate the periodontal condition of class III malocclusion patients who had not undergone orthodontic treatment. Materials and Methods: The sample included cone-beam computed tomography scans of 24 Korean subjects (3 male and 21 female). Alveolar bone thickness (ABT), alveolar bone area (ABA), alveolar bone loss (ABL), and fenestration of the maxillary and mandibular incisors were measured using 3-dimensional imaging software. Results: All incisors displayed an ABT of less than 1.0 mm from the labial surface to root level 7 (70% of the root length). A statistically significant difference was observed between the mandibular labial and lingual ABAs and between the maxillary labial and mandibular labial ABAs. The lingual ABA of the mandibular lateral incisors was larger than that of the mandibular central incisors. ABL was severe on the labial surface. A statistically significant difference was observed between the maxillary and mandibular labial ABL values(21.8% and 34.4%, respectively). Mandibular lingual ABL (27.6%) was significantly more severe than maxillary lingual ABL (18.3%) (P<0.05). Eighty-two fenestrations were found on the labial surfaces of the incisors, while only 2 fenestrations were observed on the lingual surfaces. Fenestrations were most commonly observed at root level 6. Conclusion: Careful evaluation is needed before orthodontic treatment to avoid iatrogenic damage of periodontal support when treating patients with class III malocclusion.