1,721,690 research outputs found
Multi-optical-wavelength ultrasound-modulated optical tomography: a phantom study
No full textWe used multiple optical wavelengths to study ultrasound-modulated optical tomography (UOT) in tissue phantoms. By using intense acoustic bursts and a CCD camera-based speckle contrast detection technique, we observed variations of the ultrasound-modulated signal at various optical absorptions. The experimental variations were found to be highly correlated with predictions from Monte Carlo simulations. By irradiating the sample at two optical wavelengths, we quantitatively estimated the total concentration and the concentration ratio of double dyes in objects embedded in tissue phantoms. The results suggest that UOT can potentially provide noninvasive functional imaging of the total concentration and oxygen saturation of hemoglobin in biological tissue. (C) 2007 Optical Society of America.X111919sciescopu
두경부암에서 항암치료의 전망과 이슈
No full text두경부 암은 전 세계적으로 6번째로 가장 많은 질환 으로 매년 60만명이 진단되고 35만명이 사망하고 전체 암의 5~6%룰 차지하는 질환이다.1) 새롭게 진단되는 두 경부암의 절반은 진행성 단계 (3 기 혹은 4기)로 진단되어， 다른 종류의 암종보다 높은 사망률을 보인다. 모든 병 기에서 5년생존률은 대략 60%정도 이며 국소적으로 존 재하던 두경부암의 절반은 2년 내에 국소전이나 전신전 이가 일어나서 생존률이 80%에서 35%까지 떨어지게 된 다. 항암치료 6개월 후에 재발한 환자들은 평균 6개월이 하의 생존률을 가지며 재발암이나 전이암환자의 평균 수명은 1년 이내이다.2
Liquid entrainment and off-take through the break at the top of a vessel
No full textIn order to determine the bleed capacity of the safety depressurization system (SDS) of Advanced Power Reactor 1400 (APR1400) in the case of total loss of feed water (TLOFW), we performed an experimental study of liquid entrainment and liquid off-take from the swelled two-phase mixture surface in a vessel. A total of 220 experimental data on the entrainment and off-take are obtained using a test vessel with a height of 2.0 m and an inner diameter of 0.3 m and a top break with a diameter of 0.05 m. Two-phase mixture levels are measured by an ultrasonic sensor within +/- 1.77% with respect to the visual level data. Droplet entrainment data are obtained with and without the top break and are compared with the existing pool entrainment data. The present droplet entrainment data have higher values than the existing pool entrainment data due to (a) the pulling toward the break of the liquid deentrained on the top wall of the vessel and (b) gas acceleration in the vicinity of the break. In the present experiment, droplet entrainment, E-fg, strongly depends upon j(g)(*)/h* and is proportional to the seventh power of j(g)(*)/h* in the same way as the off-take data. The empirical correlation for the onset of off-take is developed in terms of the Froude number (Fr-g) at the break and the non-dimensional inception height (h(b)/d). This correlation shows agreement with the present experimental data within +/- 15%. The present off-take quality data show agreement with Schrock's off-take quality correlation with the rms error of 15.8%. (c) 2005 Elsevier B.V. All rights reserved
On the horizontal wobbling of an object levitated by near-field acoustic levitation
No full textA circular planar object can be levitated with several hundreds of microns by ultrasonic near-field acoustic levitation ( NFAL). However, when both the sound source and the levitated object are circularly shaped and the center of the levitated object does not coincide with the source center, instability problem often occurs. When this happens, it becomes difficult to pick up or transport the object for the next process. In this study, when the center of the levitated object was of set from the source center, the moving direction of the levitated object was predicted by using the time averaged potential around the levitated object. The wobbling frequency of the levitated object was calculated by analyzing the nonlinear wobbling motion of the object. It was shown that the predicted wobbling frequencies agreed with measured ones well. Finally, a safe zone was suggested to avoid the unstable movement of an object. (c) 2007 Elsevier B. V. All rights reserved
High Speed Decoding of Context-based Adaptive Binary Arithmetic Code using Most Probable Symbol Prediction
No full textCHF characteristics of R-134a flowing upward in uniformly heated vertical tube
No full textAn experimental study of the critical heat flux (CHF) using R-134a in uniformly heated vertical tube was performed and 182 CHF data points were obtained from the present work to investigate the CHF characteristics of R-134a. The investigated flow parameters in R-134a were: (1) outlet pressures of 13, 16.5, 23.9 bar, (2) mass fluxes of 285-1300 kg/ m2 s, (3) subcooling temperatures of 5-40C. The CHF tests were performed in a 17.04 mm I.D. test section with heated length of 3 m. The parametric trends of CHF show a general agreement with previous understanding in the water. To assess the suitability of the CHF test using R-134a for modeling the CHF in water, Bowring correlation and Katto correlation were used in the present investigation. It was found that the present test results coincided well with the data predicted with both correlations. It demonstrates that the R-134a can be used as the CHF modeling fluid of water for the investigated flow conditions and geometric condition. 2005 Elsevier Ltd. All rights reserved
A study of an arc sensor model for gas metal arc welding with rotating arc - Part 1: dynamic simulation of wire melting
No full textA dynamic wire melting phenomenon is found in rotating arc welding since self-regulation of the arc length is not fully performed. Consequently welding current and electrode extension vary rapidly in high speed rotating arc operation. This paper presents the dynamic simulation of wire melting by using the variable space network method and by modelling the heat flux from the molten end of the wire into the electrode. The simulations are compared with experimental results from other references to show a fairly good agreement. By using simulation analyses, it is clarified how the characteristics of the welding power source affect the sensitivity of the arc sensor
2.5 Gb/s x 16 channel bidirectional transmission over 560 km of single mode fiber using bidirectional EDFA based on spectrally interleaved synchronized etalon filter
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