• Nuclear Engineering and Technology
• /
• 제55권7호
• /
• pp.2454-2465
• /
• 2023

Film boiling may lead to burnout of the heating element. Even though burnout does not occur, the heating element is subject to deformation because it is not sufficiently strong to withstand external loads. In particular, the ballooning and rupture of a tube under film boiling are important phenomena in the field of nuclear reactor safety. If the tube-type cladding of nuclear fuel ruptures owing to high internal pressure and thermal load, radioactive materials inside the cladding are released to the coolant. Therefore, predicting the ballooning and rupture is important. This study presents numerical simulations to predict the ballooning behavior and rupture time of a horizontal tube at high internal pressure under saturated film boiling. To do so, a multi-step coupled simulation of conjugated film boiling heat transfer and ballooning using creep model is adopted. The numerical methods and models are validated against experimental values. Two different nonuniform heat flux distributions and four different internal pressures are considered. The three-step simulation is enough to obtain a convergent result. However, the single-step simulation also successfully predicts the rupture time. This is because the film boiling heat transfer characteristics are slightly affected by the tube geometry related to creep ballooning.

• Tuberculosis and Respiratory Diseases
• /
• 제66권6호
• /
• pp.431-436
• /
• 2009

Background: In order to access the role of ballooning in patients with post-tuberculosis bronchial stenosis (PTBS), medical records of patients who underwent the procedure were reviewed. Methods: Twenty-nine PTBS patients underwent balloon dilatation between May 1999 and November 2000 at Samsung Medical Center. The median age was 28 (range 16~62 year) and most patients were female (n=27, 93%). The mean number of ballooning procedures was 2.4 (range 1~8) and the interval between ballooning procedures was 76.2$\pm$69.7 days. Results: In general, the $FEV_1$ was improved after ballooning (from 66.2.$\pm$11.9% predicted to 73.5$\pm$13.0% predicted, p=0.0004). Among 29 patients who underwent ballooning, a clinically successful outcome was observed in 16 patients (55%). Comparison between the successful and unsuccessful groups showed that favorable factors for a successful outcome were a higher pre-9ballooning $FEV_1$ (71.1$\pm$8.1 vs. 60.2$\pm$13.3% predicted), higher post-9ballooning $FEV_1$ (89.2$\pm$7.8 vs. 63.4$\pm$9.2% predicted) and absence of left upper lobe collapse. The clinical outcome was unsuccessful in all eight patients with a pre-9ballooning $FEV_1$ $\leq$57% of predicted or with complete left upper lobe collapse. Conclusion: In conclusion, ballooning appears to be helpful in patients with PTBS, especially when the pre-ballooning $FEV_1$ >57% of predicted and there is no complete left upper lobe lung collapse.

• 한국발생생물학회지:발생과생식
• /
• 제22권1호
• /
• pp.105-109
• /
• 2018

A 40-year-old G1 P0 L0 A1 woman was referred to our clinic with 6-year history of infertility. Before visiting the clinic, she had 3 cycles of In-Vitro Fertilization (IVF) procedures (2 cycles of Controlled Ovarian Stimulation-IVF and 1 cycle of frozen-thawed Embryo Transfer (ET)) at other clinic. She had medical history of abortion at early gestation following FET (frozen-thawed-ET). The patient had complete type of septate uterus, double cervix and longitudinal vaginal septum. Vaginal septotomy was done first and 1 month later, hysteroscopic septoplasty was followed using ballooning filled with dye. After septoplasty, we inserted ballooning and left for several days to compress septal endometrium on the septectomy area. All procedures were done in the ambulatory operating room without laparoscopy or admission. 3 months later, she had in vitro fertilization-embryo transfer (IVF-ET) and FET procedures in our clinic. She had successful pregnancy and now is at 22 weeks of gestation. New ambulatory septoplasty using dye-filled ballooning is easy, safe and minimally invasive surgery for treatment of complete septate uterus.

• Nuclear Engineering and Technology
• /
• 제53권10호
• /
• pp.3379-3397
• /
• 2021

In this study, a multi-physics modeling method was developed to analyze a nuclear fuel rod's thermo-mechanical behavior especially for high temperature anisotropic creep deformation during ballooning and burst occurring in Loss of Coolant Accident (LOCA). Based on transient heat transfer and nonlinear mechanical analysis, the present work newly incorporated the nuclear fuel rod's special characteristics which include gap heat transfer, temperature and burnup dependent material properties, and especially for high temperature creep with material anisotropy. The proposed method was tested through various benchmark analyses and showed good agreements with analytical solutions. From the validation study with a cladding burst experiment which postulates the LOCA scenario, it was shown that the present development could predict the ballooning and burst behaviors accurately and showed the capability to predict anisotropic creep behavior during the LOCA. Moreover, in order to verify the anisotropic creep methodology proposed in this study, the comparison between modeling and experiment was made with isotropic material assumption. It was found that the present methodology with anisotropic creep could predict ballooning and burst more accurately and showed more realistic behavior of the cladding.

• 한국자동차공학회논문집
• /
• 제24권6호
• /
• pp.702-708
• /
• 2016

The torque converter is deformed according to the rotating speed and control pressure when engine power is transferred to the transmission. This deformation, which is called ballooning phenomenon, occurs mainly at the outer side by the centrifugal force of the automatic transmission fluid (ATF) and the control pressure from the valve body. Although the torque converter is slightly deformed when rotating, the ballooning phenomenon affects fluid performance, efficiency and durability. Thus, expansion characteristics analysis is important in determining torus size, control pressure and structure. In this paper, an analysis equation and FEM model was developed to investigate the expansion characteristics. Using this model, structural analysis was performed to investigate the relationships between deformation and the torus diameter. The results were confirmed by comparing with the test results.

• International Journal of Aeronautical and Space Sciences
• /
• 제9권1호
• /
• pp.137-146
• /
• 2008

Proper amount of entrained air and nip force should be also considered to minimize ballooning phenomenon since tight contact between a roller and web is required. In this paper, various web materials, PET(Polyester) and OPP(Oriented Poly Propylene) have been selected and investigated to satisfy high-speed printing requirement. Several web speeds, web tensions, and temperature conditions are imposed on each web materials and the pressure and gap profiles as well as nip force have been calculated. Increase of both the winding roller radius and the incoming wrap angle is considered under proper taper tension at 500 m/min of rewinding roller. By solving coupled Reynolds equation and web deflection equation simultaneously, the fluid-structure interaction process has been developed and is applied to the rewinding roller to investigate the ballooning phenomenon which causes guiding problems in high-speed printing performance conditions. By adjusting the linear taper tension, stress distribution between rewinding webs can be remarkably reduced and stable pressure and gap profile with ignorable ballooning phenomenon have been found.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2002년도 추계학술발표논문집
• /
• pp.81-90
• /
• 2002

Air entrainment of a winding roll with a nip roller was studied numerically. The amount of air entrainment between two rotating rollers was obtained by solving lubrication equation, Reynolds equation, which neglect the existence of a web. However, the numerical model of this study included the web existence, therefore it considered the two lubricating air films between a winding roll and a web and also between a nip roller and the web. The pressure profiles and gap profiles of the two films were obtained by solving lubrication equation for the two air films and force balance equation of the web. Ballooning phenomenon was examined in terms of nip force, wrap angle, web stiffness, web speed, and web tension. This ballooning phenomenon caused by the back flow of the air film blocked by the nip roller. Air entrainment of the two numerical models was compared.

• 천문학회보
• /
• 제35권2호
• /
• pp.48.1-48.1
• /
• 2010

A numerical simulation study of the solar coronal plasma reveals that a ballooning instability can develop in the course of flux rope merging. When magnetic field lines from different flux ropes reconnect, a new field line connecting farther footpoints is generated. Since the field line length abruptly increases, the field line expands outward. If the plasma beta is low, this expansion takes place more or less evenly over the whole field line. If, on the other hand, the plasma beta is high enough somewhere in this field line, the outward expansion is not even, but is localized as in a bulging balloon. This ballooning section of the magnetic field penetrates out of the overlying field, and eventually the originally underlying field and the overlying field come to interchange their apex positions. This process may explain how a field structure that has stably been confined by an overlying field can occasionally show a localized eruptive behavior.

• 천문학회보
• /
• 제36권2호
• /
• pp.84.2-84.2
• /
• 2011

A numerical simulation study of the solar coronal plasma reveals that a ballooning instability can develop in the course of flux rope merging. When magnetic field lines from different flux ropes reconnect, a new field line connecting farther footpoints is generated. Since the field line length abruptly increases, the field line expands outward. If the plasma beta is low, this expansion takes place more or less evenly over the whole field line. If, on the other hand, the plasma beta is high enough somewhere in this field line, the outward expansion is not even, but is localized as in a bulging balloon. This ballooning section of the magnetic field penetrates out of the overlying field, and eventually the originally underlying field and the overlying field come to interchange their apex positions. This process may explain how a field structure that has stably been confined by an overlying field can occasionally show a localized eruptive behavior.

• Biomolecules & Therapeutics
• /
• 제4권1호
• /
• pp.89-96
• /
• 1996

The effect of Cimicifuga heracleifolia on CC1$_4$-induced hepatotoxicity was investigated. Cimicifuga heracleifolia has been used to diaphoresis, antipyretics and detoxification in oriental remedy. We examined the effect of Cimicifuga heracleifolia methanol extract by blood chemical analysis and histopathologic examination. ALT and AST were decreased by 38% and 67% in pretreatment group of Cimicifuga heracleifolia compared to CC1$_4$control group respectively. There were significant changes neither in total protein, albumin, triglyceride and cholesterol nor in BUN and creatinine. In histopathologic examination, there were severe necrosis and hemorrhage with infiltration of inflammatory cells around the central vein, zone 3 in the liver of CC1$_4$ treated rat. Ballooning degeneration of hepatocytes were frequently noted in the periphery of the hemorrhagic necrosis. In Cimicifuga heracleifolia pretreatment group, we observed mild degree of ballooning degeneration and inflammatory cell infiltration. No gross necrosis was observed. We measured malondialdehyde (MDA) formation by TBA method. It showed that the formation of MDA in Cimicifuga heracleifolia pretreatment group was decreased compared to the $CCl_4$control group. We got the result of the effect of Cimicifuga heracleifolia on CC1$_4$-induced hepatotoxicity by decreasing serum ALT and AST. It seems that the decrease of lipid peroxidation is related to the recovery effect.