• Journal of radiological science and technology
• /
• v.41 no.2
• /
• pp.109-113
• /
• 2018

Despite the continuous development of software, it is continuously pursued to enlarge the examination area of FOV in order to reduce the factors of inconsistency in images that appear in continuous examination during wide area examination using contrast agent such as whole body angiography. In this study, we investigated the optimal FOV by comparing the SNR values according to the changes of FOV. The change of the FOV was gradually changed to $270{\times}200$, $300{\times}223$, $330{\times}244$, $360{\times}266$ and $380{\times}281$. SE images at TR 450 msec and TE 10 msec, FSE images at TR 2,000 msec, TE 80 msec, and GE images were scanned at TR 117 msec, and TE 16 msec. SNR values were calculated from the mean values of signal intensities of five phantom images and the signal intensity values of four background standard deviations. As a result of the study, the signal intensity and the SNR value according to the change of the FOV value gradually increased as the FOV was increased, but it was found that the SNR value decreased at a constant size. In conclusion, the results are different from previous studies that the SNR increases as the FOV increases. The cause of these results could not be confirmed. However methods that can be imaged and included within the effective FOV should be considered.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.244-249
• /
• 2004

In this paper, shielding effectiveness(SE) of the shielding paint of electromagnetic(EM) waves was investigated with actual experiments. The shielding paint used in this study were made of powder of conductive materials - Ag, Cu, Al, Sn, Ni. Cr, Graphite and Charcoal etc. with a solubility in oil and water. Also, the paper was used as a base sheet. The experiment was carried out by using a shielding evaluator(Shielding box) TR17302 with an ADVANTEST spectrum analyzer, model R3361C. It was found from the experimental results that silver, copper, nickel were good candidates as a shielding material against the EM waves with increasing the SE as the composite was laminated. The characteristics of the SE against the EM waves depended on a mode of preparation of specimen. The effects of density of particles on the SE were studied about the EM shielding paint. The SE strongly depended on the electric resistance by density of painting particles. SE increased as the density of particles was increasing.

• Toxicological Research
• /
• v.23 no.3
• /
• pp.239-244
• /
• 2007

Respirable particles cause many occupational and environmental diseases of the lung. To study these diseases, laboratory animals are often exposed to these particles. Inhalation and instillation are the well-known techniques for experimental exposures of the lung to respirable particles. Recently, another technique called oropharyngeal aspiration (OPA) has been introduced for exposing the lung to pathogens and/or particles. The conventional OPA technique for the mouse is generally carried out using a micropipette with a fixed slant board. In order to modify the conventional OPA in this study, anesthetized mice were placed on an adjustable slant board, a syringe pump was used to deliver the solution to the oropharynx, and the mice were allowed to recover in vertically positioned tubes for 6 minutes until fully awaked. Most importantly, the whole process of OPA could be carried out simply by an examiner. This modified OPA technique was validated by exposing the mouse lung to Evans Blue dye with a success rate of 95%.

• Journal of the Korean Applied Science and Technology
• /
• v.27 no.4
• /
• pp.508-514
• /
• 2010

Regenerated cellulose fibers were prepared from three pulps containing different degree of polymerization(DP) and $\alpha$-cellulose contents by dry-jet wet spinning technique with cellulose dope in N-methylmorpholin N-oxide (NMMO). The effect of antioxidant, n-propyl gallate (PG) on the properties of different regenerated celluloses was studied using X-ray diffraction, copper number calculation, and viscometry. The degradaqtion of regenerated cellulose from pulp containing higher DP and lower $\alpha$-cellulose content was occurred more seriously. The tensile strength and initial modulus of regenerated cellulose fiber obtained from NMMO dope with PG were higher than those of fiber obtained from NMMO dope without PG. All fibers showed the round shape cross section and typical cellulose II crystalline structure.

• Journal of Cardiovascular Imaging
• /
• v.31 no.1
• /
• pp.51-61
• /
• 2023

BACKGROUND: Valvular heart disease (VHD) is a common cause of cardiovascular morbidity and mortality worldwide; however, its epidemiological profile in Korea requires elucidation. METHODS: In this nationwide retrospective cohort study from the Korean valve survey, which collected clinical and echocardiographic data on VHD from 45 medical centers, we identified 4,089 patients with VHD between September and October 2019. RESULTS: The aortic valve was the most commonly affected valve (n = 1,956 [47.8%]), followed by the mitral valve (n = 1,598 [39.1%]) and tricuspid valve (n = 1,172 [28.6%]). There were 1,188 cases of aortic stenosis (AS) and 926 cases of aortic regurgitation. The most common etiology of AS was degenerative disease (78.9%). The proportion of AS increased with age and accounted for the largest proportion of VHD in patients aged 80-89 years. There were 1,384 cases of mitral regurgitation (MR) and 244 cases of mitral stenosis (MS). The most common etiologies for primary and secondary MR were degenerative disease (44.3%) and non-ischemic heart disease (63.0%), respectively, whereas rheumatic disease (74.6%) was the predominant cause of MS. There were 1,172 tricuspid regurgitation (TR) cases, of which 46.9% were isolated and 53.1% were associated with other valvular diseases, most commonly with MR. The most common type of TR was secondary (90.2%), while primary accounted for 6.1%. CONCLUSIONS: This report demonstrates the current epidemiological status of VHD in Korea. The results of this study can be used as fundamental data for developing Korean guidelines for VHD.

• Toxicological Research
• /
• v.27 no.1
• /
• pp.49-52
• /
• 2011

The aim of this study is to investigate how many leiomyoma patients are exposed to bisphenol-A (BPA), an endocrine disruptor, and whether the serum concentration of BPA is related to leiomyoma growth. Initially, 128 patients were divided into one control and three leiomyoma groups (mild, moderate and severe) according to the size of the leiomyomas. Serum BPA concentrations were measured by liquid chromatography and mass spectrometry (LC/MS). Nearly two-thirds of leiomyoma patients were exposed to BPA and the range of BPA was from non-detection to 2.603 ng/ml. The mean BPA concentrations in the groups were $1.015{\pm}0.775\;ng/ml$ (control), $0.774{\pm}0.834\;ng/ml$ (mild), $1.261{\pm}0.797\;ng/ml$ (moderate) and $1.244{\pm}0.860\;ng/ml$ (severe) (p = 0.158). After recombination into two group, Group 1 (control plus mild) vs. Group 2 (moderate plus severe), higher level was found in Group 2 even with no statistical significance (p = 0.06). In conclusion, about two-thirds of leiomyoma patients were exposed to BPA, but it may not have growth promoting effect on leiomyoma.