• Progress in Superconductivity and Cryogenics
• /
• v.16 no.4
• /
• pp.44-48
• /
• 2014

A liquid nitrogen-cooled prepolarization ($B_p$) coil made for ultra-low field nuclear magnetic resonance and magnetic resonance imaging (ULF-MR) designed to generate 7 mT/A was fabricated. However, with suspected internal insulation failure, the coil was investigated in order to find out the source of the failure. This paper reports detailed build of the failed $B_p$ coil and a number of analysis methods utilized to figure out the source and the mode of failure. The analysis revealed that pyrolytic graphite sheet linings put on either sides of the coil for better thermal conduction acted as an electrical bridge between inner and outer layers of the coil to short out the coil whenever a moderately high voltage was applied across the coil. A simple model circuit simulation corroborated the analysis and further revealed that the failed insulation acted effectively as a damping resistor of $R_{d,eff}=6{\Omega}$ across the coil. This damping resistance produced a 50 ms-long voltage tail after the coil current was ramped down, making the coil not suitable for use in ULF-MR, which requires complete removal of magnetic field from $B_p$ coil within milliseconds.

• Korean Journal of Optics and Photonics
• /
• v.16 no.6
• /
• pp.494-499
• /
• 2005

We have demonstrated a fiber short-wavelength filter with a good cut-off property using dissimilar dispersive properties between? a thermally expanded cored fiber and an external medium. Side-polishing is applied to coupling between the fiber and the external medium. The experimental results revealed that the bend edge wavelength can be adjusted by controlling the degree of core expansion. Futhermore, the sharpness of wavelength response? was significantly? improved by employing expanded core fiber instead of a conventional single mode fiber. Tuning range of the band edge wavelength exceeded 400 m based on thermo-optic effect of the external medium.

• Journal of Environmental Science International
• /
• v.29 no.11
• /
• pp.1065-1078
• /
• 2020

The statistical characteristics of aerosol-cloud interactions over East Asia were investigated using Moderate Resolution Imaging Spectroradiometer satellite data. The long-term relationship between various aerosol and cloud parameters was estimated using correlation analysis, principle component analysis, and Aerosol Indirect Effect (AIE) estimation. In correlation analysis, Aerosol Optical Depth (AOD) was positively Correlated with Cloud Condensation Nuclei (CCN) and Cloud Fraction (CF), but negatively correlated with Cloud Top Temperature (CTT) and Cloud Top Pressure (CTP). Fine Mode Fraction (FMF) and CCN were positively correlated over the ocean because of sea spray. In principle component analysis, AOD and FMF were influenced by water vapor. In particular, AOD was positively influenced by CF, and negatively by CTT and CTP over the ocean. In AIE estimation, the AIE value in each cloud layer and type was mostly negative (Twomey effect) but sometimes positive (anti-Twomey effect). This is related to regional, environmental, seasonal, and meteorological effects. Rigorous and extensive studies on aerosol-cloud interactions over East Asia should be conducted via micro- and macro-scale investigations, to determine chemical characteristics using various meteorological instruments.

• Imaging Science in Dentistry
• /
• v.48 no.1
• /
• pp.21-30
• /
• 2018

Purpose: To calculate the effective doses of cone-beam computed tomography (CBCT) using personal computer-based Monte Carlo (PCXMC) software (Radiation and Nuclear Safety Authority, Helsinki, Finland) and to compare the calculated effective doses with those measured using thermoluminescent dosimeters (TLDs) and an anthropomorphic phantom. Materials and Methods: An Alphard VEGA CBCT scanner (Asahi Roentgen Ind. Co., Kyoto, Japan) with multiple fields of view (FOVs) was used for this study. The effective doses of the scout and main projections of CBCT using 1 large and 2 medium FOVs with a height >10 cm were calculated using PCXMC and PCXMCRotation software and then were compared with the doses obtained using TLD-100 LiF and an anthropomorphic adult human male phantom. Furthermore, it was described how to determine the reference points on the Y- and Z-axes in PCXMC, the important dose-determining factors in this software. Results: The effective doses at CBCT for 1 large ($20.0cm{\times}17.9cm$) and 2 medium FOVs ($15.4cm{\times}15.4cm$ and $10.2cm{\times}10.2cm$) calculated by the PCXMC software were 181, 300, and $158{\mu}Sv$, respectively. These values were comparable (16%-18% smaller) to those obtained through TLD measurements in each mode. Conclusion: The use of PCXMC software could be an alternative to the TLD measurement method for effective dose estimation in CBCT with large and medium FOVs.

• Journal of Chest Surgery
• /
• v.40 no.2 s.271
• /
• pp.128-131
• /
• 2007

da $Vinci^{TM}$ Surgical System is an advanced mode of minimal invasive surgery, using 3-dimensional imaging system and robotic arms which can mimic the dexterity of the human hand. Thus, various operations can be performed with minimal incision and limited surgical field and the merits of minimal invasive surgery can be maximized by using it. We report our first experience of robotic open heart surgery using the da $Vinci^{TM}$ Surgical System for repairing atrial septal defect.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.20 no.4
• /
• pp.252-258
• /
• 2017

Purpose: Blunt trauma of pancreas in children is uncommon and its management varies from observational to early operative intervention. We analysed the feasibility and outcome of non-operative management in all grades of paediatric pancreatic injuries. Methods: A total of 15 patients of pancreatic trauma seen in a Paediatric Surgery Unit were retrospectively analyzed. Results: Age of the patients ranged from 3-11 years (mean, 7.7 years). The mode of injury was local trauma in 9 children. Only 3 patients had associated injuries and all were haemodynamically stable. Serum amylase levels were raised in 12 patients at admission which ranged from 400-1,000 IU. Computed tomography scan made a correct diagnosis in 14 patients. Grades of the injury varied from grade I-V (1, 3, 6, 4, 1 patients respectively). Fourteen patients were managed conservatively. One patient underwent laparotomy for suspected superior mesenteric hematoma. The average duration of enteral feeds was 3.7 days and of hospital stay was 9.4 days. Six patients formed pancreatic pseudocysts; two were managed conservatively while the other four underwent cystogastrostomy. The patients were followed up for a period of 1-12 years. All remained asymptomatic and none had exocrine or endocrine deficiencies. Conclusion: Non-operative treatment for isolated blunt trauma of pancreas in children may be safely followed for all the grades of injury; if associated injuries requiring surgical intervention are ruled out with a good quality imaging and the patients are hemodynamically stable. It did not increase the hospital stay and morbidity and avoided operative intervention on acutely injured pancreas.

• Investigative Magnetic Resonance Imaging
• /
• v.23 no.1
• /
• pp.55-64
• /
• 2019

Purpose: One of the suggested potential mechanisms of tinnitus is an alteration in perception in the neural auditory pathway. The aim of this study was to investigate the difference in laterality in functional connectivity between tinnitus patients and healthy controls using resting state functional MRI (rs-fMRI). Materials and Methods: Thirty-eight chronic tinnitus subjects and 45 age-matched healthy controls were enrolled in this study. Connectivity was investigated using independent component analysis, and the laterality index map was calculated based on auditory (AN) and dorsal attention (DAN), default mode (DMN), sensorimotor, salience (SalN), and visual networks (VNs). The laterality index (LI) of tinnitus subjects was compared with that of normal controls using region-of-interest (ROI) and voxel-based methods and a two-sample unpaired t-test. Pearson correlation was conducted to assess the associations between the LI in each network and clinical variables. Results: The AN and VN showed significant differences in LI between the two groups in ROI analysis (P < 0.05), and the tinnitus group had clusters with significantly decreased laterality of AN, SalN, and VN in voxel-based comparisons. The AN was positively correlated with tinnitus distress (tinnitus handicap inventory), and the SalN was negatively correlated with symptom duration (P < 0.05). Conclusion: The results of this study suggest that various functional networks related to psychological distress can be modified by tinnitus, and that this interrelation can present differently on the right and left sides, according to the dominance of the network.

• PNF and Movement
• /
• v.19 no.2
• /
• pp.215-223
• /
• 2021

Purpose: This study aimed to compare the contraction ratios of the abdominal muscles and the preferential activation ratios of the transversus abdominis muscle (TrA) during the abdominal drawing-in maneuver (ADIM) in the hook-lying, sitting, and standing positions. Methods: This study included 30 healthy participants. The thicknesses of the TrA, internal oblique muscle (IO), and external oblique muscle (EO) were measured at rest and during the ADIM in the hook-lying, sitting, and standing positions using B-mode ultrasound imaging. The contraction ratios of these muscles and the preferential activation ratios of the TrA were calculated for each position. Results: The contraction ratio of the TrA and preferential activation ratio of the TrA during the ADIM in the hook-lying position were significantly higher than those in the sitting and standing positions (p < 0.05). The contraction ratio of the TrA during the ADIM in the sitting position was significantly higher than that in the standing position (p < 0.05). Conclusion: The hook-lying position tended to facilitate TrA activity better than the sitting position. Furthermore, the sitting position tended to facilitate TrA activity better than the standing position. These findings suggest that the ADIM in the hook-lying position should be implemented before that in the sitting position and that the ADIM in the sitting position should be implemented before that in the standing position.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.46.1-46.1
• /
• 2021

Hydrated asteroids get widespread attention for the evolution of water in the Solar System, especially thanks to the recent successes of the Hayabusa2 and OSIRIS-REx space missions. The target asteroids of these missions are believed to be fragments that have experienced aqueous alteration in their parent bodies [3]. Although hydrated asteroids have been studied well via spectroscopy, focusing on the 0.7 um or the 2.7 um absorption bands [2, 3, 4], polarimetric properties of these asteroids have rarely been investigated. In this study, we conducted a polarimetric observation of 18 C-complex main-belt asteroids with the 1.6-m Pirka telescope at the Nayoro Observatory of Hokkaido University, Japan. We used a polarimetric imaging mode of the Multi-Spectral Imager (MSI) with the standard Rc-band filter (the central wavelength at 0.64 um) [5]. As a result, we found that all of these hydrated asteroids indicate deep negative branches of their polarimetric profiles. Accordingly, the hydrated asteroids have the polarization minima (Pmin), whose values are significantly lower than any other taxonomic types of asteroids (including C-group asteroids). Because Pmin depends on albedo, particle size, and porosity of the surface materials [1], we suspect that hydrated asteroids are distinctive from other asteroids in terms of these physical properties. In this presentation, we introduce our polarimetric observation and findings. We discuss why hydrated asteroids indicate such low Pmin values, comparing Pmin with spectral features at 0.7 um and 2.7 um based on the observation results.

• Journal of Ginseng Research
• /
• v.48 no.2
• /
• pp.171-180
• /
• 2024

Background: Epimers of ginsenoside Rg3 (Rg3) have a low bioavailability and are prone to deglycosylation, which produces epimers of ginsenoside Rh2 (S-Rh2 and R-Rh2) and protopanaxadiol (S-PPD and R-PPD). The aim of this study was to compare the efficacy and potency of these molecules as anti-cancer agents. Methods: Crystal violet staining was used to study the anti-proliferatory action of the molecules on a human epithelial breast cancer cell line, MDA-MB-231, and human umbilical vein endothelial cells (HUVEC) and compare their potency. Cell death and cell cycle were studied using flow cytometry and mode of cell death was studied using live cell imaging. Anti-angiogenic effects of the drug were studied using loop formation assay. Molecular docking showed the interaction of these molecules with vascular endothelial growth factor receptor-2 (VEGFR2) and aquaporin (AQP) water channels. VEGF bioassay was used to study the interaction of Rh2 with VEGFR2, in vitro. Results: HUVEC was the more sensitive cell line to the anti-proliferative effects of S-Rh2, S-PPD and R-PPD. The molecules induced necroptosis/necrosis in MDA-MB-231 and apoptosis in HUVEC. S-Rh2 was the most potent inhibitor of loop formation. In silico molecular docking predicted a good binding score between Rh2 or PPD and the ATP-binding pocket of VEGFR2. VEGF bioassay showed that Rh2 was an allosteric modulator of VEGFR2. In addition, SRh2 and PPD had good binding scores with AQP1 and AQP5, both of which play roles in cell migration and proliferation. Conclusion: The combination of these molecules might be responsible for the anti-cancer effects observed by Rg3.