• Title, Summary, Keyword: Radial Ejection

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Flow Analysis in a Rotating Container with Axial Injection and Radial Ejection (축방향 유입과 반경방향 유출이 있는 회전용기 내의 유동해석)

  • Park, Jun-Sang;Sohn, Jin-Gug
    • Journal of the Korean Society of Visualization
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    • v.9 no.1
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    • pp.49-54
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    • 2011
  • An investigation has been made of a viscous incompressible flow in a circular cylindrical tank. The flow is driven by the spinning bottom disk of tank together with/without central injection and radial uniform-ejection through the sidewall. Numerical solutions of steady and unsteady flows to 3-dimensional Navier-Stokes equation were obtained for several cases of injection strength. In a moderate flow rate of injection, the mass transfer occurs through the boundary layers but, as the flow rate increases, the inner region far from the container walls takes part in mass transfer.

Development of a Ejection Gas Generator for precluding Erosive Burning by using Bundle Cylindrical Grains (침식연소가 방지되는 사출용 다발 원통형 그레인 가스발생기 개발)

  • Oh, Seok-Jin;Cha, Hong-Seok;Jang, Seung-Gyo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.432-439
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    • 2011
  • An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the legnth-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.

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Development of a Ejection Gas Generator for Precluding Erosive Burning by Using Bundle Cylindrical Grains (침식연소가 방지되는 사출용 다발 원통형 그레인 가스발생기 개발)

  • Oh, Seok-Jin;Cha, Hong-Seok;Jang, Seung-Gyo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.16 no.3
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    • pp.69-76
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    • 2012
  • An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the length-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.

Development of a gas generator to obtain highly progressive performance using bundle cylindrical grains (Highly progressive 성능을 위한 다발 원통형 그레인 가스발생기 개발)

  • Oh, Seok-Jin;Cha, Hong-Seok;Lee, Yeung-Jo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.141-144
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    • 2009
  • This paper presents an achieving method of highly progressive pressure gradient to enhance the missile ejection system's performance by using a gas generator. To obtain a stable burning, the decrease of a grain's L/D is proposed except making radial holes through the grain. New approach by applying adjustment of a grain's L/D reduces the maximum acceleration level by about 33% than that of reference model.

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Left Ventricle Segmentation Algorithm through Radial Threshold Determination on Cardiac MRI (심장 자기공명영상에서 방사형 임계치 결정법을 통한 좌심실 분할 알고리즘)

  • Moon, Chang-Bae;Lee, Hae-Yeoun;Kim, Byeong-Man;Shin, Yoon-Sik
    • Journal of KIISE:Software and Applications
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    • v.36 no.10
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    • pp.825-835
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    • 2009
  • The advance in medical technology has decreased death rates from diseases such as tubercle, pneumonia, malnutrition, and hepatitis. However, death rates from cardiac diseases are still increasing. To prevent cardiac diseases and quantify cardiac function, magnetic resonance imaging not harmful to the body is used for calculating blood volumes and ejection fraction(EF) on routine clinics. In this paper, automatic left ventricle(LV) segmentation is presented to segment LV and calculate blood volume and EF, which can replace labor intensive and time consuming manual contouring. Radial threshold determination is designed to segment LV and blood volume and EF are calculated. Especially, basal slices which were difficult to segment in previous researches are segmented automatically almost without user intervention. On short axis cardiac MRI of 36 subjects, the presented algorithm is compared with manual contouring and General Electronic MASS software. The results show that the presented algorithm performs in similar to the manual contouring and outperforms the MASS software in accuracy.

Predictive Value of Cardiac Magnetic Resonance Imaging-Derived Myocardial Strain for Poor Outcomes in Patients with Acute Myocarditis

  • Lee, Ji Won;Jeong, Yeon Joo;Lee, Geewon;Lee, Nam Kyung;Lee, Hye Won;Kim, Jin You;Choi, Bum-Sung;Choo, Ki Seok
    • Korean Journal of Radiology
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    • v.18 no.4
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    • pp.643-654
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    • 2017
  • Objective: To evaluate the utility of cardiovascular magnetic resonance (CMR)-derived myocardial strain measurement for the prediction of poor outcomes in patients with acute myocarditis. Materials and Methods: We retrospectively analyzed data from 37 patients with acute myocarditis who underwent CMR. Left ventricular (LV) size, LV mass index, ejection fraction and presence of myocardial late gadolinium enhancement (LGE) were analyzed. LV circumferential strain ($Ecc_{SAX}$), radial strain ($Err_{SAX}$) from mid-ventricular level short-axis cine views and LV longitudinal strain ($Ell_{LV}$), radial strain ($Err_{Lax}$) measurements from 2-chamber long-axis views were obtained. In total, 31 of 37 patients (83.8%) underwent follow-up echocardiography. The primary outcome was major adverse cardiovascular event (MACE). Incomplete LV functional recovery was a secondary outcome. Results: During an average follow-up of 41 months, 11 of 37 patients (29.7%) experienced MACE. Multivariable Cox proportional hazard regression analysis, which included LV mass index, LV ejection fraction, the presence of LGE, $Ecc_{SAX}$, $Err_{SAX}$, $Ell_{LV}$, and $Err_{Lax}$ values, indicated that the presence of LGE (hazard ratio, 42.88; p = 0.014), together with ErrLax (hazard ratio, 0.77 per 1%, p = 0.004), was a significant predictor of MACE. Kaplan-Meier analysis demonstrated worse outcomes in patient with LGE and an $Err_{Lax}$ value ${\leq}9.48%$. Multivariable backward regression analysis revealed that $Err_{Lax}$ values were the only significant predictors of LV functional recovery (hazard ratio, 0.54 per 1%; p = 0.042). Conclusion: CMR-derived $Err_{Lax}$ values can predict poor outcomes, both MACE and incomplete LV functional recovery, in patients with acute myocarditis, while LGE is only a predictor of MACE.

Analysis of Suitability of Radial Artery Graft as Bypass Conduit after Transradial Catheterization (관상동맥조영술에 사용된 요골동맥의 우회도관으로서의 적합성에 대한 분석)

  • 신윤철;이동석;지현근;김응중
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.37 no.11
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    • pp.897-902
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    • 2004
  • Background: Although great concerns have been raised regarding the suitability of the use of the radial artery as a bypass conduit after transradial catheterization, there has been no studies that examined this issue in Korea. The purpose of this study was to compare clinical and angiographic results of radial artery grafting between patients with and without previous transradial catheterization. Material and Method: From January 2000 to February 2004, a total of 93 patients underwent coronary artery bypass grafting using the radial artery: 49 patients received preoperative transradial catheterization for coronary angiography (group I) and 44 patients did not (group II). These patients were retrospectively reviewed. Result: There was no significant difference in sex ratio, age, clinical diagnosis, risk factors, ejection fraction and early clinical outcomes between two groups. The graft patency rates in groups I and II were both 100% in the internal thoracic artery and in the radial artery, and 85% and 86% in the saphenous vein. respectively. The stenosis-free graft patency in groups I and II were 93% and 81% in the radial artery respectively but no statistical significance was shown. Conclusion: There was no significant difference in graft patency at postoperative coronary angiography between two groups. Radial artery graft after transradial catherization seems to be suitable for bypass conduit in short-term analysis.

Change of arterial pulse wave characteristic by measurement posture and brachial blood pressure (측정 자세 및 상완 혈압에 의한 맥파 특성 변화)

  • Nam, Ki-Chang;Kim, Eun-Gun;Hoe, Hyun;Huh, Young
    • Science of Emotion and Sensibility
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    • v.12 no.3
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    • pp.299-306
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    • 2009
  • In this study, pulse waves were measured at radial artery using non-invasive tonometric pulse pressure measurement system, SphygmoCor(AtCor, Australia), according to subject's posture. Then it was analysed whether the pulse wave parameters, which contain heart activities, change among three different postures (upright stand, sit, and supine). And it was also verified that the pulse wave parameters change among blood pressure level groups(hypotensive, normotensive, and hypertensive). As a results, posture effects were verified in time information of pulse wave rather than amplitude. But some parameters calculated by ratio of two amplitude, such as augmented index(AI) and ratio of central aortic pulse and radial artery pulse, showed significant difference according to postures. In post hoc test, time to the $1^{st}$ and $2^{nd}$ pulse peak(P_$T_1$, and P_$T_2$), ED(ejection duration), and HR(heart rate) showed significant difference among posture groups with each other. In comparison of blood pressure groups, it was verified that the parameters related to amplitude of pulse wave showed significant difference rather than time information.

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Early Result of Coronary Artery Bypass Grafting Using the Radial Artery (요골동맥를 이용한 관상동맥우회술의 조기성적)

  • 박진홍;지현근;신윤철;김응중
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.36 no.10
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    • pp.734-740
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    • 2003
  • Increasing interest in the use of arterial conduits is based on the better patency of left internal thoracic artery (LITA) than that of saphenous vein (SV) graft and radial artery (RA) is emerging as one of them. We compared the early result of coronary artery bypass grafting (CABG) using UTA and RA (RA group) with CABG using UTA and SV only (SV group). Material and Method: We compared the early operative results of 45 cases in RA group with 45 cases in SV group selected from 165 cases who had CABG between January 2000 and December 2002. The two groups had similar profiles of age, sex, NYHA functional class, left ventricular ejection fraction and coronary angiographic anatomy. We analysed each group on the preoperative risk factors and operative results. Result: There were no statically signigicant difference between groups in operative mortality and each morbidities (stroke, IABP insertion, perioperative MI), respectively. However, the overall incidence of mortality and morbidities was lower in RA group compared to SV group (p < 0.05). RA group (2.93$\pm$0.62 days) had shorter duration of ICU stay than SV group (3.55$\pm$0.95 days) (p<0.001). The patency on postoperative coronary angiography at 7∼14 days after operation in RA group patients were 100% of LITA and RA and 94.9% of SV. Conclusion: We had better early operative results in RA group compared with SV group.

The advancing techniques and sputtering effects of oxide films fabricated by Stationary Plasma Thruster (SPT) with Ar and $O_2$ gases

  • Jung Cho;Yury Ermakov;Yoon, Ki-Hyun;Koh, Seok-Keun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.216-216
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    • 1999
  • The usage of a stationary plasma thruster (SPT) ion source, invented previously for space application in Russia, in experiments with surface modifications and film deposition systems is reported here. Plasma in the SPT is formed and accelerated in electric discharge taking place in the crossed axial electric and radial magnetic fields. Brief description of the construction of specific model of SPT used in the experiments is presented. With gas flow rate 39ml/min, ion current distributions at several distances from the source are obtained. These was equal to 1~3 mA/$\textrm{cm}^2$ within an ion beam ejection angle of $\pm$20$^{\circ}$with discharge voltage 160V for Ar as a working gas. Such an extremely high ion current density allows us to obtain the Ti metal films with deposition rate of $\AA$/sec by sputtering of Ti target. It is shown a possibility of using of reactive gases in SPT (O2 and N2) along with high purity inert gases used for cathode to prevent the latter contamination. It is shown the SPT can be operated at the discharge and accelerating boltages up to 600V. The results of presented experiments show high promises of the SPT in sputtering and surface modification systems for deposition of oxide thin films on Si or polymer substrates for semiconductor devices, optical coatings and metal corrosion barrier layers. Also, we have been tried to establish in application of the modeling expertise gained in electric and ionic propulsion to permit numerical simulation of additional processing systems. In this mechanism, it will be compared with conventional DC sputtering for film microstructure, chemical composition and crystallographic considerations.

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