• Title/Summary/Keyword: Leak Fluid

Search Result 132, Processing Time 0.026 seconds

NUMERICAL APPROACH FOR QUANTIFICATION OF SELFWASTAGE PHENOMENA IN SODIUM-COOLED FAST REACTOR

  • JANG, SUNGHYON;TAKATA, TAKASHI;YAMAGUCHI, AKIRA;UCHIBORI, AKIHIRO;KURIHARA, AKIKAZU;OHSHIMA, HIROYUKI
    • Nuclear Engineering and Technology
    • /
    • v.47 no.6
    • /
    • pp.700-711
    • /
    • 2015
  • Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

Bile Peritonitis Due to Spontaneous Rupture of Choledochal Cyst Diagnosed by Hepatobiliary Scintigraphy in an Infant (영아에서 간담도 스캔으로 진단된 총 담관낭의 자연 천공에 의한 담즙성 복막염 1례)

  • Kim, Jong-Seok;Lim, Jang-Hun;Bae, Sang-Nam;Lee, Jun-Woo;Kim, In-Ju;Park, Jae-Hong
    • Pediatric Gastroenterology, Hepatology & Nutrition
    • /
    • v.5 no.2
    • /
    • pp.186-191
    • /
    • 2002
  • Choledochal cyst is a congenital anomaly with classic triad of abdominal pain, jaundice and right upper abdominal mass. Bile peritonitis caused by cyst rupture is relatively not rare in infancy. The mechanism of rupture must be epithelial irritation of the biliary tract by refluxed pancreatic juice caused by pancreatico-biliary malunion associated with mural immaturity in infancy, rather than an abnormal rise in ductal pressure or congenital mural weakness at a certain point. We experienced a case of bile peritonitis caused by spontanenous rupture of choledochal cyst in a 10-month-old girl presented with abdominal distension, persistent fever, diarrhea, irritability and intractable ascites. She was presumed as having bile peritonitis by bile colored ascitic fluid with elevated bilirubin level and diagnosis was made by $^{99m}Tc$ DISIDA hepatobiliary scan showing extrahepatic biliary leak. The perforated cyst was surgically removed and the biliary tree was reconstructed with a Roux-en-Y hepaticojejunostomy.

  • PDF

Development of Static Seal for a Liquid Rocket Engine (액체 로켓 엔진 스태틱 실 개발)

  • Jeon, Seong Min;Yoon, Suk-Hwan;Chung, Taegeum
    • Journal of Aerospace System Engineering
    • /
    • v.16 no.4
    • /
    • pp.53-59
    • /
    • 2022
  • Static seals are used to seal high temperature gas and cryogenic fluid under high pressure, at interfaces between liquid rocket engine components such as combustion chamber, turbopump, gas generator, valves, etc. As thermal expansion and contraction at assembly interfaces cause undesirable leakage under cryogenic and high temperature environments, static seals applied for sealing of joint interfaces without relative motion should be designed properly. The additional function of rotation at the sealing face is also required for static seals, when the spherical flange is used for improvement of assembly at misalignment interfaces. In this study, structural analysis and leak tightness test of simulating test rig for several important interfaces are performed, to verify structural integrity of static seals.

Anterior Cranial Base Reconstruction in Complex Craniomaxillofacial Trauma: An Algorithmic Approach and Single-Surgeon's Experience

  • Shakir, Sameer;Card, Elizabeth B.;Kimia, Rotem;Greives, Matthew R.;Nguyen, Phuong D.
    • Archives of Plastic Surgery
    • /
    • v.49 no.2
    • /
    • pp.174-183
    • /
    • 2022
  • Management of traumatic skull base fractures and associated complications pose a unique reconstructive challenge. The goals of skull base reconstruction include structural support for the brain and orbit, separation of the central nervous system from the aerodigestive tract, volume to decrease dead space, and restoration of the three-dimensional appearance of the face and cranium with bone and soft tissues. An open bicoronal approach is the most commonly used technique for craniofacial disassembly of the bifrontal region, with evacuation of intracranial hemorrhage and dural repair performed prior to reconstruction. Depending on the defect size and underlying patient and operative factors, reconstruction may involve bony reconstruction using autografts, allografts, or prosthetics in addition to soft tissue reconstruction using vascularized local or distant tissues. The vast majority of traumatic anterior cranial fossa (ACF) injuries resulting in smaller defects of the cranial base itself can be successfully reconstructed using local pedicled pericranial or galeal flaps. Compared with historical nonvascularized ACF reconstructive options, vascularized reconstruction using pericranial and/or galeal flaps has decreased the rate of cerebrospinal fluid (CSF) leak from 25 to 6.5%. We review the existing literature on this uncommon entity and present our case series of n = 6 patients undergoing traumatic reconstruction of the ACF at an urban Level 1 trauma center from 2016 to 2018. There were no postoperative CSF leaks, mucoceles, episodes of meningitis, or deaths during the study follow-up period. In conclusion, use of pericranial, galeal, and free flaps, as indicated, can provide reliable and durable reconstruction of a wide variety of injuries.

A Numerical Study on the Mitigation Effect of Water Curtain for SiCl4 Toxic Gas Release (SiCl4 누출 시 수막설비의 방재효과에 대한 수치 해석 연구)

  • Tae In Ryu;Eunmi Lee;Seungha Kim;Seong-mi Kang;Chang-hyun Shin;Seungbum Jo
    • Journal of the Korean Society of Safety
    • /
    • v.38 no.3
    • /
    • pp.43-50
    • /
    • 2023
  • Silicone tetrachloride (SiCl4) leak accidents cause enormous human and environmental damage because it is highly toxic. Some handling facilities use water curtains to reduce the impact range of SiCl4. Although the water curtain is known as one of the most efficient technologies for post-release mitigation, its effect on reducing SiCl4 concentration needs to be investigated scientifically and quantitatively. In this study, three-dimensional computational fluid dynamics (CFD) was used to investigate the physical and chemical effects of water curtains as a release-mitigation system for SiCl4. SiCl4 is released and dispersed five seconds prior to the operation of the water curtain. Once the water curtain works, the SiCl4 reacts chemically with the water and its concentration decreases rapidly; it reaches an emergency response planning guidelines level 2 (ERPG-2) of 5 parts per million (ppm) at about 570 m. We observed, however, that the physical effect of water curtains on reducing SiCl4 concentration is insignificant when the chemical effect is eliminated. These results are crucial since they can be a scientific and quantitative basis for the 'technical guidelines for estimating the accident affected range'. In order to protect the public from chemical accidents, more toxic gas mitigation technologies need to be developed.

Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review

  • Andrea Y. Lo;Roy P. Yu;Anjali C. Raghuram;Michael N. Cooper;Holly J. Thompson;Charles Y. Liu;Alex K. Wong
    • Archives of Plastic Surgery
    • /
    • v.49 no.6
    • /
    • pp.729-739
    • /
    • 2022
  • Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm2, and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology (p = 0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

Surgical Management and Long-Term Results of Rathke's Cleft Cyst

  • Seung-Ho, Seo;Kihwan, Hwang;So Young, Ji;Jung Ho, Han;Chae-Yong, Kim
    • Journal of Korean Neurosurgical Society
    • /
    • v.66 no.1
    • /
    • pp.82-89
    • /
    • 2023
  • Objective : Rathke's cleft cysts (RCCs) are nonneoplastic cysts. Most of them are asymptomatic and stable; when symptomatic, RCCs are surgically fenestrated and drained. However, the outcomes remain unclear. The authors evaluated the outcomes of RCC decompression. Methods : Between 2004 and 2019, 32 RCCs were decompressed in a single tertiary institution. The clinical characteristics, intraoperative findings, postoperative complications, and endocrinological and surgical outcomes were retrospectively reviewed. Patients who underwent sequential imaging at least twice and at least 12 months after surgery were included in the analysis. Results : Patients' mean age was 40.8±14.9 years, and 62.5% were women. The mean follow-up duration was 62.3±48.6 months. In 21 patients (65.6%), no residual cysts were identified on postoperative magnetic resonance imaging. Of the 18 patients with preoperative visual field defects, 17 (94.4%) experienced postoperative visual improvement. Postoperative complications included endocrinological deterioration in 11 patients (34.4%), permanent diabetes insipidus in 11 (34.4%), infection in four (12.5%), intrasellar hemorrhage in three (9.4%), and cerebrospinal fluid leak in two (6.3%). Follow-up images revealed cyst recurrence in nine patients (28.1%), an average of 20.4 months after surgery; in three patients, the cysts were symptomatic, and resection was repeated. Multivariable analysis revealed that postoperative endocrinological deterioration was the only independent factor associated with cyst recurrence (p=0.028; hazard ratio, 6.800). Conclusion : Our findings showed that although only cyst fenestration for decompression was performed to preserve pituitary function, more pituitary dysfunction occurred than expected. Besides, the postoperative hormonal deterioration itself acted as a risk factor for cyst recurrence. In conclusion, surgery for RCC should be more careful.

Surgical Strategy for Skull Base Chordomas : Transnasal Midline Approach or Transcranial Lateral Approach

  • Wang, Benlin;Li, Qi;Sun, Yang;Tong, Xiaoguang
    • Journal of Korean Neurosurgical Society
    • /
    • v.65 no.3
    • /
    • pp.457-468
    • /
    • 2022
  • Objective : The clinical management paradigm of skull base chordomas is still challenging. Surgical resection plays an important role of affecting the prognosis. Endonasal endoscopic approach (EEA) has gradually become the preferred surgical approach in most cases, but traditional transcranial surgery cannot be completely replaced. This study presents a comparison of the results of the two surgical strategies and a summary of the treatment algorithms for skull base chordomas. Methods : We retrospectively analyzed the surgical outcomes and follow-up data of 48 patients with skull base chordomas diagnosed pathologically who received transnasal midline approaches (TMA) and transcranial lateral approaches (TLA) from 2010 to 2020. Results : Among the 48 patients, 36 cases were adopted TMA and 12 cases were performed with TLA. In terms of gross total resection (GTR) rate, 27.8% in TMA and 16.7% in TLA and with EEA alone it was increased to 38.9%, while 29.7% in primary surgery. In TMA, the cerebrospinal fluid (CSF) leak remains the most common complication (13 cases, 36.1%), other main complications included death, cranial nerve palsy, hypopituitarism, all the comparisons were no statistical significance. The Karnofsky Performance Scale scores in TMA were all better than those in TLA at different time, and the overall survival (OS) and recurrence free survival/progression free survival was just the reverse. Conclusion : The EEA for skull base chordomas resection has improved the GTR rate, but transcranial approach is still an alternative approach. It is necessary to select an appropriate surgical approach based on the location and the pattern of tumor growth in order to obtain the best surgical outcomes.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.26 no.12
    • /
    • pp.605-619
    • /
    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Protective Effect of the Inhibition of PAF Remodeling and Adhesion Molecule on the Oxidative Stress of the Lungs of Rats Given Endotoxin Intratracheally (내독소에 의해 유도된 급성 폐 손상에서 PAF Remodelling 및 Adhesion Molecule의 억제가 폐장내 Oxidative Stress에 미치는 영향)

  • Shin, Tae Rim;Na, Bo Kyung;Lee, Young Man
    • Tuberculosis and Respiratory Diseases
    • /
    • v.58 no.3
    • /
    • pp.276-284
    • /
    • 2005
  • Backgraound : There have been many reports on the pathogenesis of sepsis-induced acute respiratory distress syndrome(ARDS) but, the precise mechanism has not been elucidated. This study examined the protective effect of an inhibition of platelet activating factor(PAF) remodeling and the adhesion molecule on the oxidative stress of the lungs in rats with an endotoxin induced acute lung injury(ALI). Methods : ALI was induced in Sprague-Dawley rats by instilling an E-coli endotoxin into the trachea. Ketotifen and fucoidan were used respectively to inhibit PAF remodeling and adhesion molecule. The lung leak index, lung myeloperoxidase(MPO) activity, bronchoalveolar lavage(BAL) fluid neutrophil count and lyso PAF acetyltransferase activity(AT), were measured and an ultrastructural study and cytochemical electron microscopy were performed. Results : The lung leak index, lung MPO activity, BAL fluid neutrophil count and lyso PAF AT activity was higher in the endotoxin-treated rats. In addition, severe destruction of the pulmonary architecture and increased hydrogen peroxide production were identified. These changes were reversed by ketotifen. However, fucoidan did not appear to have any protective effects. Conclusion : The inhibition of PAF remodeling appeared to be effective in decreasing the endotoxin-induced ALI. In addition, this effect might be derived from the inhibition of neutrophilic oxidative stress. However, the inhibition of the adhesion molecules by fucoidan appeared to be ineffective in decreasing the endotoxin-induced ALI.