• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.447-453
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• 2020

This study accurately measured the half-life of the ¹⁷⁹Re radioactive isotope using the 100 MeV proton and high-purity HPGe gamma ray measurement system generated from a high-energy proton linear accelerator at the Korea Atomic Energy Research Institute. The result obtained is 19.64 ± 0.26 min. Compared with the past results of the half-life of the ¹⁷⁹Re radioisotope known to date, the results of B. Harmatz published in 1960 and B. J. Meijer published in 1975 measured the median value higher than the results obtained in this study. In the case of K. J. Hofstetter, published in 1966, a very large error is also characteristic. This result showed a tendency that the center value was very consistent with the result of this study. The results of Coral M. Baglin's 19.5 min published in 2009 are very consistent with the error range. The obtained measured result was compared with the result of ENSDF (Evaluated Nuclear Structure Data File). Through this study, more reliable values were measured for the results of the half-life of the ¹⁷⁹Re, which was previously incorrect, and the validity of the recently published results of Coral M. Baglin was confirmed.

• Parasites, Hosts and Diseases
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• v.52 no.1
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• pp.93-97
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• 2014

Subolesin (4D8), the ortholog of insect akirins, is a highly conserved protective antigen and thus has the potential for development of a broad-spectrum vaccine against ticks and mosquitoes. To date, no protective antigens have been characterized nor tested as candidate vaccines against Dermacentor silvarum bites and transmission of associated pathogens. In this study, we cloned the open reading frame (ORF) of D. silvarum 4D8 cDNA (Ds4D8), which consisted of 498 bp encoding 165 amino acid residues. The results of sequence alignments and phylogenetic analysis demonstrated that D. silvarum 4D8 (Ds4D8) is highly conserved showing more than 81% identity of amino acid sequences with those of other hard ticks. Additionally, Ds4D8 containing restriction sites was ligated into the pET-32(a+) expression vector and the recombinant plasmid was transformed into Escherichia coli rosetta. The recombinant Ds4D8 (rDs4D8) was induced by isopropyl ${\beta}$-D-thiogalactopyranoside (IPTG) and purified using Ni affinity chromatography. The SDS-PAGE results showed that the molecular weight of rDs4D8 was 40 kDa, which was consistent with the expected molecular mass considering 22 kDa histidine-tagged thioredoxin (TRX) protein from the expression vector. Western blot results showed that rabbit anti-D. silvarum serum recognized the expressed rDs4D8, suggesting an immune response against rDs4D8. These results provided the basis for developing a candidate vaccine against D. silvarum ticks and transmission of associated pathogens.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.12 no.2
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• pp.177-182
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• 2009

Purpose: Colitis is a condition associated with a spectrum of altered morphologic changes and cellular adhesion. E-cadherin plays a key role in the establishment and maintenance of epithelial tissue structure and cell-cell adhesion. The purpose of this study is to evaluate E-cadherin expression in colonic epithelium of various colitis in children. Methods: The expressions of E-cadherin were examined in 39 cases of colonic mucosal biopsy specimen using immunohistochemical staining. When more than 50 percent of cells exhibited uniformly the same intensity and pattern of immunostaining as the adjacent normal mucosa, the antigen expression was considered normal. Abnormal expression was defined when less than 50 percent of cells stained, when cells showed a heterogeneously weak or altered distribution, or when complete absence of staining was observed. Results: Fifteen cases with non-specific colitis (38.5%), 7 cases of with Crohn's disease (17.9%), 5 cases of infectious colitis and milk protein sensitive proctocolitis (12.8%), 3 cases of ulcerative colitis (7.7%), 2 cases of Henoch-Schonlein purpura colitis (5.1%), one case of Behcet's disease and ischemic colitis (2.6%) were included in this study. E-cadherin expression was decreased in all kinds of colitis. Reduced expression of E-cadherin was observed in 77 percent of cases. E-cadherin was weaker or no expression in reparative epithelium and "ulcer associated cell lineage". Conclusion: Altered expression of E-cadherin occurs during mucosal inflammation in any kinds of colitis. These changes may be involved in promoting cell migration during epithelial restitution of the gastrointestinal mucosa.

• Pediatric Infection and Vaccine
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• v.11 no.1
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• pp.126-130
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• 2004

Neisseria meningitidis is a leading cause of meningitis and septicemia in children and young adults. Meningococcemia, the most severe form of infection, represents a part of the various spectrum of the illness, and its clinical manifestations varied from mild fever and occult bacteriemia to fulminant catastrophic events(e.g., sepsis, shock, and death) within a few hours after onset of symptoms. Complement deficiencies, either congenital or acqired, increase the risk for invasive meningococcal disease. Since C3 plays a critical role in the complement cascade, congenital C3 deficiency or conditions that decrease C3(e.g., systemic lupus erythematosus, cirrhosis, nephritis, C3 nephritic factor) increase the risk for invasive disease due to pyogenic bacteria including N. meningitidis. We had experienced a case of meningococcemia and meningococcal meningitis presenting with mild fever, petechiae, and purpura. The patient was a 7-year old male. He had mild fever, vomiting, headache, nuchal rigidity, petechiae and purpura on both lower extremities, which spreaded to the whole body. His blood culture grew Neisseria meningitidis. The diagnosis of meningococcal meningitis was confirmed by examination of cerebrospinal fluid. The clinical symptoms of the illness were improved after treatment of antibiotics(cefotaxime) for 12 days. However the patient had developed generalized edema, microscopic hematuria & proteinuria on the third day after admission. High ASO titer and low serum C3 level were also noted. The microscopic hematuria returned to normal about 2 months after discharge. The C3 level returned to normal range about 3~4 months after discharge. we report a case of combined acute poststreptococcal glomerulonephritis and acute invasive meningococcal disease with reference review.

• Childhood Kidney Diseases
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• v.12 no.1
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• pp.88-92
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• 2008

Infection of Epstein-Barr virus(EBV) gives rise to a broad spectrum of clinical manifestations in children. Although renal involvement is rare, diverse renal manifestations are known from hematuria to acute renal failure. Secondary membranous nephropathy(MN) associated with systemic EBV infection is an uncommon renal pathology and only two cases have been reported. We are adding another case of MN associated with EBV infection in a child. An 8-year-old girl was admitted for renal biopsy. She had been followed up for microscopic hematuria and intermittent proteinuria for 5 months. There had been no specific findings in serology and radiology. Tonsil biopsy had been done due to exudative tonsillar hypertrophy and enlarged multiple cervical lymph nodes. And it showed EBV-associated lymphoproliferative findings. Serologic tests for EBV showed positive evidence of recent infection; viral capsid antigen(VCA) IgM was borderline positive, VCA IgG and early antigen IgG were positive, and EB nuclear antigen IgG was negative. In Situ Hybridization of tonsil for EBV mRNA was positive. Because her proteinuria and hematuria were aggravated at that time(protein 3 +, RBC >60/HPF), renal biopsy was done. Renal biopsy showed the findings of MN, characterized by thickened capillary walls with epimembranous spikes on light microscopy and subepithelial, mesangial and subendothelial electron dense deposits on electron microscopy. On immunofluorescence microscopy, IgG, C1q, kappa and lambda chains were positive. After steroid administration, proteinuria and hematuria resolved gradually within 6 months.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.123-131
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• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.

• Journal of radiological science and technology
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• v.34 no.1
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• pp.43-50
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• 2011

In this study we modeled the varian 2100C/D linear accelerator head and multi-leaf collimator by simulation with the GEANT4 Monte Carlo toolkit. Then central axis percentage depth dose profiles and lateral dose profiles within homogeneous water phantom($50{\times}50{\times}50\;cm^3$) were evaluated with 6 MV photon beam. The simulations were performed in two stages. In the first stage, photon energy spectrum at the target were computed were computed. Then spectra data was directly irradiated in the water phantom using sampling techniques. The simulation data were compared with experimental data to evaluate the accuracy of the model. Results showed that two data were matched within 2% error boundary. The proposed method will be applied for simulation of dose calculation and dose distribution study.

• Journal of radiological science and technology
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• v.37 no.2
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• pp.143-150
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• 2014

This study was designated to investigate the bremsstrahlung and radiation dose by beta rays. Radiation attenuation from I-131 treatment ward was analyzed using radio protective apron. Shielding materials which is included lead or water were simulated in Monte Carlo Simulation then the spectrum on interaction was analyzed. The shielding materials were categorized according to the thickness. 0.25mm and 0.5mm thick lead and 0.1mm and 0.2mm thick water shielding materials were configured in Monte Carlo Simulation for this study. Only lead shielding method and water plus lead shielding method were carried. As a results, when 0.5mm thick lead shielding method was performed, the radiation dose was similar to the results with water plus lead shielding method. In case of using 0.25mm thick lead shielding, the shielding effect was somewhat less. However, that shielding method cause dose reduction of about 60% compare with non-shielding material.

• Journal of radiological science and technology
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• v.37 no.2
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• pp.117-124
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• 2014

This study has investigated the effects of the defects in the probe elements influence Doppler images in the medical ultrasonic scanners. This work was implemented that the quality of Doppler images depended on the extent and location of the probe element defected. The probe performance was rated in terms of the number of piezoelectric elements lost and this was studied in the experiment by electrical disconnection to the elements. The results showed that Doppler velocity became rapidly reduced as the defected elements encountered with the element group activated at the Doppler mode, not as the flow velocity. The effect of the probe defect is decreased when the defects occurred at the element group activated for Doppler mode, as was increased the number of the elements. It was observed that the higher the flow velocity of Doppler flow phantom is, the wider the spectrum of Doppler is. And the Doppler velocity soared up and the dispersion of image brightness is increased when the defected elements got out of the elements activated at Doppler mode. The result showed that TADVP(time-average-Doppler-velocity-profile) is decreased with the increase of the probe element defect, especilly in the region of high frequency. It is expected that the research of various defects of probe elements are needed, and this study can be practical tools for probe based ultrasonic QA in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.153-153
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• 2010

Recently, to develop GaN-based light-emitting diodes (LEDs) with better performances, various approaches have been suggested by many research groups. In particular, using the patterned sapphire substrate technique has shown the improvement in both internal quantum efficiency and light extraction properties of GaN-based LEDs. In this paper, we discuss the influences of the direction of the hexagonal-structure arrays of lens-shaped patterns (HSAPs) formed on sapphire substrates on the crystal, optical, and electrical properties of InGaN/GaN multi-quantum-well (MQW) LEDs. The basic direction of the HSAPs is normal (HSAPN) with respect to the primary flat zone of a c-plane sapphire substrate. Another HSAP tilted by 30o (HSAP30) from the HSAPN structure was used to investigate the effects of the pattern direction. The full width at half maximums (FWHMs) of the double-crystal x-ray diffraction (DCXRD) spectrum for the (0002) and (1-102) planes of the HSAPN are 320.4 and 381.6 arcsecs., respectively, which are relatively narrower compared to those of the HSP30. The photoluminescence intensity for the HSAPN structure was ~1.2 times stronger than that for the HSAP30. From the electroluminescence (EL) measurements, the intensity for both structures are almost similar. In addition, the effects of the area of the individual lens pattern consisting of the hexagonal-structure arrays are discussed using the concept of the planar area fraction (PAF) defined as the following equation; PAF = [1-(patterns area/total unit areas)] For the relatively small PAF region up to 0.494, the influences of the HSAP direction on the LED characteristics were significant. However, the direction effects of the HSAP became small with increasing the PAF.