• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.7-12
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• 2019

Purpose: During the pelvic radiation therapy, it is performed with controlling bladder volume because the range of irradiation is changed depending on the bladder volume. Therefore in this study, we evaluate the accuracy of BVI by tracing the change of bladder volume using ultrasonic pulse diagnosis equipment(BVI 6100, Medical supply Co. LTD) Material and Methods: From January 2017 to September 2018, 19 patients who received pelvic radiation therapy at Pusan National University Hospital were included. To treat the patient, we compared that the bladder volume obtained from the BVI and the bladder volume obtained from the CBCT image then we evaluated for significance. Results: There was a significant correlation of r=0.773, BVI and CBCT in the whole volume section. However, based on the bladder volume in the RTP Image the p value was shown to be 0 at 125~175cc and lower than 0.05 at 175~275cc, And more than 0.05 at 275~375cc. Conclusions: In this study, the patient whose bladder volume is above than 275cc, there is a significance of bladder volume between BVI and CBCT image. However, we could make a decision to be undermined the reliability of BVI measurement in the case of the patient with emptied his urine. Therefore, it is possible to acquire a significant value for 175~275cc patients to use the correction value of BVI and the appropriate tolerance of volume.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.855-864
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• 2013

Active tab is one of the promising technology for the BVI (blade-vortex interaction) noise reduction, and analysis of noise reduction performance is very important phase of the technology development. For the purpose of analysing the performance of noise reduction using active tab, CAMRAD II model for a model-scale rotor system was constructed utilizing structural design result and airfoil aerodynamic data generated by CFD (computational fluid dynamics) calculation. HHC strategy was applied to descent flight condition and air-load was calculated by CAMRAD II then variations of BVI noise was calculated by in-house program. Calculation result with respect to tab length and control phase changes showed BVI noise could be reduced by -3.3dB.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.329-335
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• 2009

The unsteady panel and time-marching free wake are applied to the rotor aerodynamics and wake behaviour. Numerical results of panel and free wake are compared and validated with experimental data. Using these methods, unsteady rotor aerodynamics in BVI condition is analyzed and discussed in detail.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.172-174
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• 2003

Nnumerical investigations of the tip vortical characteristics were conducted with lateral tip blowing to reduce Blade-Vortex Interaction (BVI) noise. The predictions of BVI noise were performed using a combined method of an unsteady Euler code with an aeroacoustic code based on Ffowcs- Williams and Hawkings formulation. A moving overlapped grid system with three types of grids (blade grid, inner and outer background grid) was used to simulate BVI of helicopter with two OLS-airfoil blades in forward/ descending flight condition. The calculated waveform of BVI noise, which is characterized by the distinct peaks caused during blade vortex interaction, clearly shows the effect of lateral blowing at tip to reduce BVI noise

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1363-1367
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• 2014

This research was conducted to compare differences in colon cancer lymphatic vessel invasion (LVI) with D2-40 antibody labeling and regular HE staining, blood vessel invasion (BVI) with CD34 antibody labeling and HE staining and to assess the possibility of using D2-40-LVI/CD34-BVI in combination for predicting stage II colon cancer prognosis and guiding adjuvant chemotherapy.Anti-D2-40 and anti-CD34 antibodies were applied to tissue samples of 220 cases of stage II colon cancer to label lymphatic vessels and small blood vessels, respectively. LVI and BVI were assessed and multivariate COX regression analysis was performed for associations with colon cancer prognosis. Regular HE staining proved unable to differentiate lymphatic vessels from blood vessels, while D2-40 selectively labeled lymphatic endothelial cell cytosol and CD34 was widely expressed in large and small blood vessels of tumors as well as normal tissues. Compared to regular HE staining, D2-40-labeling for LVI and CD34-labeling for BVI significantly increased positive rate (22.3% vs 10.0% for LVI, and 19.1% vs 9.1% for BVI). Multivariate analysis indicated that TNM stage, pathology tissue type, post-surgery adjuvant chemotherapy, D2-40-LVI, and CD34-BVI were independent factors affecting whole group colon cancer prognosis, while HE staining-BVI, HE staining-LVI were not significantly related. When CD34-BVI/D2-40-LVI were used in combination for detection, the risk of death for patients with two or one positive results was 5.003 times that in the LVI(-)&BVI(-) group (95% CI 2.365 - 9.679). D2-40 antibody LVI labeling and CD34 antibody BVI labeling have higher specificity and accuracy than regular HE staining and can be used as molecular biological indicators for prognosis prediction and guidance of adjuvant chemotherapy for stage II colon cancer.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.2
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• pp.48-57
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• 2008

The noise is one of the serious problems concerning helicopters operations. The issue of helicopter external noise generated mainly from a helicopter rotor has always affected the use of rotorcrafts, especially in the urban environment. The noise sources depend on the flight configurations. In particular, a noise generated by the interaction between blades and tip vortices mainly occurs during descent flight. This noise is called blade-vortex interaction (BVI) noise, and this BVI noise is particularly penalizing for helicopters. In this paper, a numerical study to capture the BVI noise is carried out. The numerical study is performed in two phases. In the first phase, a 2D simulation based on parallel BYI event of Kitapliglu et al experiment is performed. In the second phase, 3D simulation based on HART Ⅱ experiment is performed. Several experimental data such as thrust, torque, blade sectional load, its derivative and vortex location are compared with calculation results and the comparison showed reasonably good agreement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.71-74
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• 2012

Generally, tone noise is generated at the rotary wing and helicopter. BVI(Blade-Vortex Interaction) noise is one of the helicopter's tone noise. The BVI noise is governed by tip-vortex characteristics such as vortex size, strength and trajectory. To avoid BVI, many methods have been developed and proposed. In this paper, rotating blade with active tab was numerically investigated to reduce BVI noise. For flow and noise simulation, the lifting surface approach and the acoustic analogy were used. Using numerical methods, the noise directivity and maximum noise position were predicted.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.249-260
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• 2003

CCD photometric observations of a W UMa type contact binary AH Cnc were performed for ten nights from December 1998 to May 1999 using a PM512 CCD camera and BVI filters attached to the 61㎝ reflector at Sobaeksan Optical Astronomy Observatory. New BVI light curves were analyzed with contact Mode 3 of the Wilson-Devinney binary model. We obtained photometric solutions and Roche geometry of this binary system. Through the analysis of the (O-C) diagram with all times of minimum light published so far and including hour's secular variations of orbital period and the mass transfer rate were calculated.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.88-98
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• 2003

Compared to the noise limits (CAN7) specified in ICAO Annex 16 for civil helicopters, the Lynx helicopter equipped with BERP blades has only 0.2 EPNdB margin in the approach case although it has more than 4 EPNdB margin in fly-over and take-off conditions. The objectives of the study described in this paper were to devise a low noise main rotor blade for the Lynx using UEAF combined with the high resolution airload model ACROT. A design requirement is that the new blade, KBERP (Korean BERP) blade should achieve a significant reduction in noise during approach(at least 6EPNdB margin) without any noise penalty in fly-over and take-off conditions and minimal performance penalty. It was decided to investigate a tip modification to the BERP blade, employing the twin vortex concept to reduce the BVI noise and to retain the excellent high speed performance characteristics of BERP. Through the parametric study, the KBERP blade with optimized twin vortices has at least a 9 EPNdB noise margin in approach flight condition with only a small penalty in fly-over and take-off conditions. The KBERP tip is thus a very cost effective wav to reduce BVI noise during approach.

• The Journal of the Acoustical Society of Korea
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• v.25 no.2E
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• pp.85-88
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• 2006

Blade-vortex interaction (BVI) is one of the most important phenomena in rotor flow since it causes undesirable intense vibration and noise. Since three dimensional Euler or Navier-Stokes solutions to BVI require very high computational cost, BVI has been approximated by airfoil-vortex interaction (AVI) in chordwise planes. To describe more realistic situations with AVI, three dimensional vortex informations such as position, core size and strength are embedded artificially to Computational Aeroacoustics (CAA) calculation at each computational time step. To implement this requirement, in this paper, a technique called free vortex embedded method was used. And the solution by this method was compared with the solution by conventional method for interaction between freely convected vortex and airfoil. For the application to three dimensional free vortex embedded CAA, two dimensional free vortex embedded CAA method was validated in advance.