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Theoretical, numerical, and experimental investigation of smoke dynamics in high-rise buildings
Ahn, Chan-Sol,Bang, Boo-Hyoung,Kim, Min-Woo,James, Scott C.,Yarin, Alexander L.,Yoon, Sam S. Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.135 No.-
<P><B>Abstract</B></P> <P>Smoke kills more people than the associated fire and thus predicting smoke spreading inside high-rise buildings is of paramount importance to structural and safety engineers. Here, the velocity, temperature, and concentration fields in large-scale turbulent smoke plumes were predicted using classical self-similar turbulent plume theory, which assumes a point fire source under open-air conditions. Turbulent fires of various heat release rates in a confined space were also simulated numerically using Fire Dynamics Simulator (FDS), which was verified against experimental data before being used to validate the analytical plume jet results. The agreement between analytical, numerical, and experimental results was good. This demonstrates for the first time that for realistic, wide shafts, analytical results from self-similar theory of free turbulent plumes are as accurate as the numerical simulations and appropriately describe experimental data. This allows engineers to avoid lengthy, cumbersome numerical simulations to estimate the consequences of smoke spreading in high-rise buildings using simple analytical formulae. In addition, parametric studies were conducted using plume theory for building heights up to 500 m and heat release rates up to 500 MW. Smoke velocity, temperature, and concentration fields described smoke evolution at different heights.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Turbulent smoke plumes predicted using classical self-similar turbulent plume theory. </LI> <LI> Turbulent fires of various heat release rates simulated numerically. </LI> <LI> Plume theory for building heights up to 500 m and heat release rates up to 500 MW. </LI> <LI> These results are useful to construction and safety engineers. </LI> </UL> </P>
지구 온난화 방지를 위한 자동차 용 대체 냉매 에어컨 시스템
유진영(Jinyoung Yoo),Scott Bang,Fortier Ryan,배유진(Yujin Bae),성낙섭(Naksup Sung) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
EU Directive 2006/40/EC prohibits use of refrigerants with global warming potential greater than 150 in Mobile Air Condition(MAC) starting 2011. This paper presents an experimental study of various alternative refrigerant MAC systems to identify a possible replacement for current R-134a. Of many proposed refrigerants, HFO-1234yf is overall more environmental friendly than R-744 to replace R-134a, based on a number of performance evaluation and risk assessments. Because HFO-1234yf is a mildly flammable, a number of different risk assessments were completed in order to evaluate its risk in vehicle usage. Many evaluations concluded that only oil ignites even at unrealistic high temperature & pure HFO-1234yf failed to ignite without oil.
Numerical investigation of smoke dynamics in unconfined and confined environments
Ahn, Chan-Sol,Bang, Boo-Hyoung,Kim, Min-Woo,Kim, Tae-Gun,James, Scott C.,Yarin, Alexander L.,Yoon, Sam S. Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.127 No.2
<P><B>Abstract</B></P> <P>Because of their implications to safety, the study of plume dynamics in high-rise buildings is a research area of interest to building engineers. In this study, the temperature, velocity, and pressure of smoke rising in buildings of various sizes were considered as functions of fire size, and were simulated using the Fire Dynamics Simulator software. Numerical results were validated against the analytical solutions for confined (building enclosure) and unconfined (open-air) systems. As the building area decreased and the fire size increased, buoyancy-driven flow accelerated and the overall building temperature increased. Additionally, the low pressure at the bottom of the building, which resulted from buoyant smoke, increased the vertical pressure gradient throughout the building. These parametric investigations can be used by building engineers concerned with smoke dynamics to develop design-safety guidelines.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Temperatures, velocities, and pressures of smoke rising in buildings were simulated. </LI> <LI> The numerical results were validated against the analytical solutions. </LI> <LI> As the building area decreased and the fire size increased, the flow was accelerated. </LI> <LI> These parametric studies can be used to develop design-safety guidelines of building. </LI> </UL> </P>
Chen, Jen-Shi,Chao, Yee,Bang, Yung-Jue,Roca, Enrique,Chung, Hyun C.,Palazzo, Felipe,Kim, Yeul H.,Myrand, Scott P.,Mullaney, Brian P.,Shen, Li J.,Linn, Carlos Lippincott Williams Wilkins, Inc. 2010 ANTICANCER DRUGS Vol.21 No.8
This phase I/II study was conducted to determine the maximum recommended dose of pemetrexed when given in combination with a fixed dose of cisplatin, and the efficacy, toxicity and association of 5,10-methylenetetrahydrofolate reductase (MTHFR) variants with this pemetrexed--cisplatin combination, in patients with unresectable, advanced gastric carcinoma. Patients 18–70 years of age, with stage IV disease or post-surgery recurrence, no earlier palliative chemotherapy, 0 or 1 Eastern Cooperative Oncology Group performance status, were included. The cisplatin dose was 75 mg/m. In phase I, the initial dose of pemetrexed was 600 mg/m, escalated in 100 mg/m increments. In phase II, efficacy, including overall response rate, overall survival, as well as toxicity and MTHFR pharmacogenetics were investigated. Phase I enrolled 16 patients; 700 mg/m was defined as pemetrexed recommended dose. Thirteen serious adverse events were reported; the most common grade 3/4 toxicities were haematologic (10 of 13, 76.9%). Phase II enrolled 73 patients, 69 qualified for safety and 68 for efficacy analysis; 65 for pharmacogenomic analysis. Overall response rate was 23.5% (14.1%, 35.4%), disease control rate 55.9%, median overall survival 11.8 months (95% confidence interval, 7.2–18.5 months), progression-free survival 4.9 months (95% confidence interval, 2.8–7.1 months), and median response duration 5.4 months. Patients with MTHFR A1298C variants had median overall survival of 6.6 months, significantly shorter than patients with the wild type (median 18.5 months, P=0.001). The pemetrexed--cisplatin combination in patients with advanced gastric cancer generates modest efficacy and a manageable toxicity profile. The reduced overall survival in patients with MTHFR A1298C polymorphism variants deserves further investigation.
Modifying capillary pressure and boiling regime of micro-porous wicks textured with graphene oxide
Jo, Hong Seok,An, Seongpil,Nguyen, Xuan Hung,Kim, Yong Il,Bang, Boo-Hyoung,James, Scott C.,Choi, Jeehoon,Yoon, Sam S. Elsevier 2018 Applied thermal engineering Vol.128 No.-
<P><B>Abstract</B></P> <P>Liquid flow inside a heat pipe due to capillary forces can be used to cool electronic devices. To promote capillary-driven flow, a multilayer, porous wicking surface was designed for optimal liquid transport. The multilayer-porous structure consists of micro-porous structure decorated with nanomaterials. Herein, we demonstrate that micro-porous copper coated with graphene oxide (GO) has elevated capillary forces that can increase both the critical heat flux and the convective heat transfer coefficient. The thin GO layer promotes hydrophilicity that enhances the wettability of the wicking surface. However, an excessively thick GO coating can decrease permeability even in the presence of increased capillary pressures such that overall flow is hindered. In this work an optimal coating thickness is identified and characterized by heat-transfer experiments and scanning electron microscopy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A highly porous wicking surface was introduced to promote capillary-driven flow in a heat pipe. </LI> <LI> Micro-porous copper coated with graphite oxide (GO) increased the critical heat flux. </LI> <LI> The thin GO layer promotes hydrophilicity that enhances the wettability of the wicking surface. </LI> <LI> Narrowed pores due to the GO layer increase the capillary pressure and the wicking effects. </LI> </UL> </P>