• International Journal of Automotive Technology
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• v.2 no.4
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• pp.165-170
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• 2001

This study is focussed on the investigation of spray characteristics from the high pressure gasoline injector for the application of gasoline direct injection engine. For the analysis of spray structure of high pressure gasoline injector; the laser scattering method with a Nd-Yag laser and the Phase Doppler particle analyzer system were applied to observe the spray development and the measurement of the droplet size and velocity of the spray, respectively. Also spatial velocity distribution of the spray droplet was measured by use of the particle image velocity system. Experimental results show that high pressure gasoline injector shapes the hollow-cone spray, and produce the upward ring shaped vortex on the spray surface region. This upward ring shaped vortex promotes the secondary atomization of fuel droplets and contributes to a uniform distribution of fuel droplets. Most of fuel droplets are distributed under 31$\mu m$ of the mean droplet size (SMD) and the frequency distribution of the droplet size under 25$\mu m$ is over 95% at 7 MPa of injection pressure. According to the experimental results of PIV system, the flow patterns of the droplets velocity distribution in spray region are in good agreement with the spray macroscopic behaviors obtained from the visualization investigation.

• Interdisciplinary Bio Central
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• v.5 no.4
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• pp.7.1-7.3
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• 2013

This essay describes G. Mendel's life and his law of inheritance. He was born in a poor family in 1822 in a hamlet in Czechs. At that time the Habsburg Empire dominated over the East Europe in which Vienna was the capital. Vienna had thus been the center of culture and learning, and attracted many artists and scholars such as W. Mozart (1756- 1791), L. Beethoven (1770-1827), C. Doppler (1803-1853), S. Freud (1856-1939), G. Mahler (1860-1911), G. Klimt (1862-1918) and E. Schiele (1890-1918). Beethoven came to Vienna to learn from Mozart. Klimt was influence by Schilele. When Mahler consulted Freud about his mental problem, Freud said to him "Your mental condition was not normal, but the condition made you creative. So, do not worry too much about it." Like that, there were many interactions among them, and Mendel was no exception. Though Mendel was poor, he was fortunate in his education and scientific research, because he could have excellent supporters in his family and out of it. He learned mathematics and physics at Vienna University under the guidance of C. Doppler. He was not totally alone when he discovered his law of inheritance. It may not be true either that his law was neglected and rediscovered in the year of 1900. As his one and only paper indicates, he was one of the earliest interdisciplinary scientists.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.9-17
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• 2008

Pseudo-3D spatial distribution of spray droplets is investigated by using Dual-mode Phase Doppler Anemometry (DPDA) in order to examine the disintegration and spreading behavior of spray exiting from liquid-propellant thruster injector. Spray injected from nozzle orifice with length-to-diameter ratio ($L/d_o$) of 1.67 and under the injection pressure of 27.6 bar is aligned to the vertical. Vertical and horizontal mean velocities of droplets, Sauter Mean Diameter (SMD), and volumetric flux decrease as droplets travel from center/upstream toward outer region/downstream of spray. Although the distribution of spray characteristic parameters is symmetric against the geometric axis of nozzle orifice, their absolute values are asymmetric.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.625-628
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• 2007

We present an efficient and robust technique to estimate the velocity of moving targets from a single SAR image. In SAR images, azimuth image shift is a well known phenomenon, which is observed in moving targets having slant-range velocity. Most methods estimated the velocity of moving targets from the distance difference between the road and moving targets or between ship and the ship wake. However, the methods could not be always applied to moving targets because it is difficult to find the road and the ship wake. We adopted a method estimating the velocity of moving targets from azimuth differentials of range-compressed image. This method is based on an assumption that Doppler center frequency shift of moving target causes a phase difference in azimuth differential values. The phase difference is linearly distorted by Doppler rate due to the geometry of SAR image. The linear distortion is eliminated from phase removal procedure, and the constant phase difference is estimated. Finally, range velocity estimates for moving targets are retrieved. This technique is tested using an ENVISAT ASAR image in which several unknown ships are presented. The theoretical accuracy of this technique is discussed by SAR simulation. The advantages and disadvantages of this method over the conventional method are also discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.113-116
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• 2008

Pseudo-3D Spatial distribution of spray droplets is investigated by using Dual-mode Phase Doppler Anemometry (DPDA) in order to examine the disintegration and spreading behavior of spray exiting from liquid-thruster injector. Spray injected from nozzle orifice with length-to-diameter ratio $(L/d_o)$ of 1.67 and at the injection pressure of 27.6 bar is aligned to the vertical. Vertical and horizontal mean velocities of droplets, Arithmetic Mean Diameter (AMD), Sauter Mean Diameter (SMD), and volumetric flux decrease as droplets travel from center/upstream toward outer region/downstream of spray.

• Journal of Chest Surgery
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• v.32 no.11
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• pp.1031-1035
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• 1999

Background: ATS mechanical valve is a recently introduced pyrolytic carbon bileaflet prosthesis. This report is to evaluate the results of hemodynamic and anticoagulant therapy after ATS valve replacement. Material and Method: From May 1995 to October 1998, 53 patients received 65 ATS prosthesis; 38 Mitral(27-33 mm), 27 Aortic(19-25 mm). 2 CABGs and 5 Tricuspid annuloplasty were taken concomitantly. The follow up period was 769 patient-months(mean 16.2$\pm$10.0), varied from 1 month to 39 months with 92.5% follow up rate. All patients were evaluated with Doppler echocardiography, 7-14 days after operation. Result: NYHA functional class was improved significantly, from 2.6$\pm$0.8 preoperatively to 1.3$\pm$0.4 postoperatively. The average value of peak and mean transvalvular pressure gradients were 25.7$\pm$13.5 mmHg, 12.7$\pm$8.3 mmHg in aortic position. In the mitral position, the average values of peak and mean transvalvular pressure gradient and valve area were 5.9$\pm$2.5 mmHg, 3.1$\pm$0.8 mmHg and 2.9$\pm$0.5 $\textrm{cm}^2$, respectively. In the anticoagulant therapy, mean INR was 2.5$\pm$0.6 in mitral valve replacement and 1.9$\pm$0.5 in aortic valve replacement. There was no anticoagulant related complication. During that period, there were 3 hospital death(5.9%) and 1 late death(1.9%). Conclusion: The early clinical results of the ATS heart valve replacement is quite satisfactory, and low target INR reginmen is safe. And long term follow of hemodynamic characteristics is also necessary.

• The Journal of Korean Medicine
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• v.26 no.1 s.61
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• pp.115-122
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• 2005

Background and objective: Gastrodiae Rhizoma (GR), the rhizoma of Gastrodia elata BL., is one of the popular drugs to treat headache, dizziness, blackout, numbness of limbs, hemiplegia, facial paralysis, dysphrasia, and infantile convulsions. It has been reported that it provides an antihypertensive effect and lowers cerebrovascular resistance in animal experiments. However, there has been no data about these effects with human subjects. In this study, the author examined the effect of Gastrodiae water extracts on blood pressure and cerebrovascular reactivity in human subjects. Methods: We selected 16 normal volunteers, who were divided into 2 groups: Gastrodiae extract administration group and placebo (creamy powder) group. Using transcranial Doppler ultrasound, we monitored changes of mean flow velocity and breath-holding induced CO2 reactivity of middle cerebral artery in both groups. Mean blood pressure, heart rate and PETCO2 were measured using Compact Anesthesia Monitor. In both groups, all evaluation was performed during basal condition, and repeated at 30, 60, and 90 min after administration. Results: Gastrodiae extract decreased CO2 reactivity after administration, reaching the lowest level at 90 minutes $(-29.1\%\;vs.\;basal\;level)$, which showed significant difference compared with the placebo group (p = 0.004). In the placebo group, the pulse rates tended to decrease over time (at 90 minute, $-5.2\%$ vs. basal level) while in the Gastrodiae group the values showed nearly no change, which showed significant difference between both groups (p = 0.036). However, the changes of mean blood pressure and mean flow velocity did not show significant difference between both groups. Conclusion : This study demonstrated that Gastrodiae extract significantly decreased breath-holding induced CO2 reactivity. This result suggests that the clinical effect of Gastrodiae extract might be caused by increasing cerebral blood flow via dilation of cerebral resistant vessels instead of antihypertensive effect.

• Korean Journal of Clinical Laboratory Science
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• v.44 no.4
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• pp.184-198
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• 2012

The purpose of intra-operative neurological monitoring (INM) is to minimize surgically induced nerve damage, sensory nerves and motor neurons without affecting the operations to proceed during surgery such as evoked potentials (EP), electromyography (EMG), electroencephalography (EEG), transcranial doppler (TCD), etc. During the course of checking a patient's condition, surveillance of ambulatory patients is a very different thing to check if the test is done under general anesthesia. INM can be possible or impossible depending on the type of drugs used and their concentrations because the monitoring is performed under anesthesia. Therefore, it is emphasized on the necessity of reviewing anesthesia which influences on INM.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.545-555
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• 2020

This paper presented efficient transceiver structure using sub-band processing for underwater communication in terms of covertness and performance improvement. In aspect of covertness, encrypted coded-bits are divided into groups, and center frequency and sub band are determined by coded-bits of each group. Therefore, as center frequencies are changed randomly, it maintain the covertness effectively. In aspect of performance improvement, the performance of underwater communication mainly depends on multi-path propagation characteristics, Doppler-spread, and frame synchronization. Accordingly, in order to overcome these effects, non-coherent energy detector and turbo equalization method are employed in receiver side. Furthermore, optimal frame synchronization was proposed. Through the simulation and lake experiment, performance analysis was conducted. Especially in the lake experiment, as a result of applying optimal frame synchronization method to receiver structure, errors are corrected in most frames.

• Korean Journal of Radiology
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• v.22 no.11
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• pp.1834-1840
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• 2021

Objective: To analyze the computational fluid dynamics (CFD) of femoral artery pseudoaneurysm (FAP), identify a suitable location and timing for percutaneous thrombin injection (PTI) based on this analysis, and report our clinical experience with the procedure. Materials and Methods: CFD can be used to analyze the hemodynamics of the human body. An analysis using CFD recommended that the suitable location of the needle tip for PTI is at the center of the aneurysm sac and the optimal timing for starting PTI is during the early inflow phase of blood into the sac. Since 2011, seven patients (three male and four female; median age, 60 years [range, 43-75 years]) with FAP were treated with PTI based on the devised suitable location and time. Prior to the procedure, color Doppler ultrasonography was performed to determine the location and timing of the thrombin injection. Results: The technical success rate of the PTI was 100%. The amount of thrombin used for the procedure ranged from 200 IU to 1000 IU (median, 500 IU). None of the patients experienced any symptoms or signs of embolic complications during the procedure. Follow-up CT images did not reveal any embolism in the lower extremities and showed complete thrombosis of the pseudoaneurysm. Conclusion: Based on our study of CFD, PTI administered centrally in the FAP during early inflow, as seen on color Doppler, can be an effective technique.