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Flame retardant behavior of diammonium phosphate in the presence of potassium nitrate
Younggeun Kim(Younggeun Kim),Kyungok Kwon(Kyungok Kwon) 한국화재소방학회 2022 한국화재소방학회 학술대회 논문집 Vol.2022 No.춘계
Various studies have been reported the use of flame retardants for treating cellulose that can aid in the development of novel flame retardants to protect cellulose-based products. The development of eco-friendly flame retardants with high contents of Phosphate(P), Potassium(K) and Nitrile(N) at the molecular level has also been reported. Potassium nitrate(KNO3) is also one of main materials in fire extinguishing systems to generate solid aerosol as an extinguishant. The condensed aerosol fire extinguisher produced the fire extinguishing aerosol which extinguished the fire efficiently through the endothermic reaction of Potassium(K) compounds, thus terminating chain reactions catch Hydrogen(H) and hydroxy(OH) radicals. The enhanced retardant effect of PN addition to Diammonium Phosphate (DAP) for cellulose might be due to the generation of potassium extinguishing agents which undergo an endothermic reaction with N2 and H2O, t hus catching radicals of H a nd OH. Experiments were carried out by using a Mettler Toledo DSC1 thermal analyzer. All experiments were conducted under N2 atmosphere and scan rates of (5~50 K min-1). The reproducibility of DSC results was < 2 % for all experiments. The activation energy of this process was calculated using the Kissinger Method, which is one of the most popular approaches for determining kinetic parameters through thermal analysis. The Kissinger Equation employed herein is as follows: ln(q/T2p) = -Ea/R(1/Tp) + ln(RA/Ea) The results reveals that the retardant capability of DAP in the presence of PN was studied by using cellulose as fuel. Our results depict that there is an optimum ratio of PN to DAP to achieve high retardancy for cellulose. The extinction time of flame and char residue is reduced due to synergic effects between DAP and PN. Our results demonstrated that DAP added with a small concentration of PN could decrease the activation energy and increase the dehydration of cellulose.
Development of an Ultrasonic Doppler Sensor-Based Swallowing Monitoring and Assessment System
Younggeun Choi(최영근),Minjae Kim(김민재),Baekhee Lee(이백희),Xiaopeng Yang,Jinwon Kim(김진원),Dohoon Kwon(권도훈),Sang-Eok Lee(이상억),HyangHee Kim(김향희),Seok In Nam(남석인),Saewon Hong(홍세원),Giltae Yang(양길태),Duk L. Na(나덕렬 대한인간공학회 2020 대한인간공학회 학술대회논문집 Vol.2020 No.10
Corrosion Rate Measurement Technique with Thin Film Electric Resistance Sensor
Kim, YoungGeun,Jung, SungWon,Song, HongSeok,Lee, SeongMin,Kho, YoungTai 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.4
There has been growing interest in corrosion monitoring since it is crucial in aging systems in that it enables one to evaluate corrosion risks and predict the service life of construction materials. In this study, we report the application of new ER corrosion probe using thin metal film for corrosion monitoring. The reliability of the new thin film probe was confirmed by comparison with traditional weight loss coupon. The corrosion rate could be determined successfully within a few days of monitoring at various situations.
Kim, Changsoo,Lee, Hodong,Kim, Kyeongsu,Lee, Younggeun,Lee, Won Bo American Chemical Society 2018 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.57 No.39
<P>Process monitoring is an important aspect of safe operation of process plants. Various methods exist that monitor the process using data-driven methods, but they all have certain limitations. For instance, most of the fault detection methods are not able to detect the fault propagation path, and some methods require a priori knowledge on the faults, or the relationships between the monitored variables. In this study, a monitoring method for accurately detecting the faults and analyzing the fault propagation path is proposed. Named the Glasso-MRF monitoring framework, this method integrates the use of the graphical lasso algorithm (G-lasso) and the Markov random field (MRF) modeling framework to divide the monitored variables into relevant groups and then detect the faults separately for each of the groups. Graphical lasso uses the lasso constraint on the inverse covariance matrix of variables within the maximum likelihood estimation problem, driving it to be of sparse form. The use of graphical lasso downsizes the process into groups that are highly correlated, relieving the computational complexity of the MRF-based monitoring so that the process can be efficiently monitored, and enabling the fault propagation path to be identified. MRF modeling can extensively model the variable relationships including cyclic structures, and can be obtained without a priori knowledge of the relationships between variables, using the iterative graphical lasso algorithm proposed in this study. The inference of MRFs are usually complex due to the existence of partition functions, but by down-sizing the system using iterative G-lasso, this problem is resolved as well. The proposed method was applied to the well-known Tennessee Eastman process to evaluate its performance. The detection accuracy of the Glasso-MRF monitoring framework was higher than any other state-of-the-art monitoring methods, including autoencoders and Bayesian networks, showing more than 95% fault detection accuracy for all of the 28 faults programmed within the Tennessee Eastman process. Also, the fault propagation path could be detected according to the difference in fault detection time of the divided groups, providing enhanced analysis of the initiated fault. These results prove that the proposed methodology can effectively detect the fault as well as show its propagation throughout the process, without any a priori knowledge of the process variables.</P> [FIG OMISSION]</BR>
Younggeun Kim,권경옥 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.7
The performance of automatic fire extinguishers (AFE) was tested using a novel nozzle distribution test in relation to a point of visual approach. The visual nozzle distribution data was obtained from the mapping of the amount of the collected fire extinguishing agent to each position and the gradient was given in accordance with the visually collected amount. The results showed that the effective discharge time was determined by the nozzle structure and its size. The visual nozzle distribution test (VNDT) provided relevant information regarding the performance efficiency of AFE, including the nozzle coverage area, the effective amount of the fire extinguishing agent and the distribution uniformity of fire extinguishing agents, and calculations for the proper amount of a fire extinguishing agent to extinguish a fire. Consequently, the results indicate the VNDT is an excellent method for analyzing the performance efficiency of AFE.
Kim, Youngho,Lee, Junghun,Kim, Younggeun,Shin, Sang-Mo,Kim, Byungkyu IOP 2011 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.21 No.1
<P>In this paper, we describe a cantilever-type electrode (CE) array-based high-throughput sorting platform, which is a tool used to separate microparticles using gravitation and negative dielectrophoretic (n-DEP) force. This platform consists of meso-size channels and a CE array, which is designed to separate a large number of target particles by differences in their dielectric material properties (DMP) and the weight of the particles. We employ a two-step separation process, with sedimentation as the first step and n-DEP as the second step. In order to differentiate the weight and the DMP of each particle, we employ the sedimentation phenomena in a vertical channel and the CE-based n-DEP in an inclined channel. By using three kinds of polystyrene beads with diameters of 10, 25 and 50 µm, the optimal population (10<SUP>7</SUP> beads ml<SUP>−1</SUP>) of particles and the appropriate length (25 mm) of the vertical channel for high performance were determined experimentally. Conclusively, by combining sedimentation and n-DEP schemes, we achieve 74.5, 94.7 and 100% separation efficiency for sorting microparticles with a diameter of 10, 25 and 50 µm, respectively.</P>