• Composites Research
• /
• v.31 no.5
• /
• pp.282-287
• /
• 2018

In this paper, we explore interfacial properties of the mineralized CNTs when they are employed as reinforcing fillers in a polymer nanocomposite using molecular dynamics (MD) simulations. Recently, several studies on mineralizing carbon nanotubes (CNTs) with an aid of nitrogen doping to CNTs have been reported. However, there is a lack of studies on the reinforcing effects of the mineralized CNTs when it is employed as a filler of nanocomposites. Silica ($SiO_2$) is used as a mineral material and poly (methyl metacrylate) (PMMA) is used as a polymer matrix. Pull-out simulations are conducted to obtain the interfacial energy and the interfacial shear stress. It was found that the silica mineralized CNTs have higher interfacial interaction with the polymer matrix. In the future, by examining various thermomechanical properties of the mineralized-CNT-filler/polymer nanocomposites, we will search for potential applications of the novel reinforcing filler.

• Resources Recycling
• /
• v.17 no.3
• /
• pp.29-34
• /
• 2008

Solvent extraction behaviors of iron(III) from chloride solution at high ionic strength condition between Alamine336 and TBP were compared by using MaCabe-Thiele diagram. Extraction isotherms of iron by the two extractants were obtained by calculating the equilibrium concentrations of iron in both phases from the initial extraction conditions. In calculating the equilibrium concentration of iron, chemical equilibria in the aqueous phase and mass balance together with the solvent extraction reaction were considered. MaCabe-Thiele diagram of iron by 1M Alamine336 indicated that two extraction stages could lead to complete extraction of 0.5M iron from 3M HCl solution at an A/O ratio of 6/5. The extraction power of 1M Alamine336 was found to be the same as 2-3M TBP. MaCabe-Thiele diagram together with the physical properties of the two extractants indicated that Alamine336 is superior to TBP in extracting ferric iron from chloride solution.

• Clean Technology
• /
• v.24 no.4
• /
• pp.357-364
• /
• 2018

Studies on the production of biogas from third generation biomass, such as micro- and macroalgae, have been conducted through experiments of various scales. In this paper, we investigated the feasibility of commercialization of integrated combined heat and power (CHP) production using biogas derived from macroalgae, i.e., seaweed biomass. For this purpose, an integrated CHP plant of industrial scale, consisting of solid oxide fuel cells, gas turbine and organic Rankine cycle, was designed and simulated using a commercial process simulator. The cost of each equipment in the plant was estimated through the calculated heat and mass balances from simulation and then the techno-economic analysis was performed. The designed integrated CHP process produces 68.4 MW of power using $36ton\;h^{-1}$ of biogas from $62.5ton\;h^{-1}$ (dry basis) of brown algae. Based on these results, various scenarios were evaluated economically and the levelized electricity cost (LEC) was calculated. When the lifetime of SOFC is 5 years and its stack price is $$225kW^{-1}$, the LEC was 12.26 ¢ $kWh^{-1}$, which is comparable to the conventional fixed power generation.

• Journal of Korea Water Resources Association
• /
• v.41 no.3
• /
• pp.243-249
• /
• 2008

Continuous stirred tank reactor(CSTR) model which can be applied to control and management of the surface flow wetland is developed to simulate the water quality in this research. The model solution is obtained from the optimization model using the least-squares and 4th-order Runge-Kutta methods. The model is applied to simulate BOD and TSS in the wetland database of U.S. EPA, in which the hydraulic and water quality data are enough and the number of pond is just one for simple analysis of running results. The model is tested in two different cases, one constant volume case and another constant volume and flow rate case considering only reaction term, mass flux term and both reaction and mass flux terms respectively. It is found that the model simulates the real water quality very well with both reaction and mass flux terms rather than only reaction term and the settling velocity of TSS becomes $0.3{\sim}0.4\;m/d$. The model can be applied in wetlands treatment efficiently.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.6
• /
• pp.536-544
• /
• 2012

It is necessary to study the material circulation of coastal ecosystem according to aquacultural activity in order to induce the sustainable production of aquaculture and the fishery environment for the useful use. Hence, it is essential to make an exact assessment for the sedimentation release flux at the sediment-water interface in the aquafarm. Sediment oxygen demand and dissolved inorganic nitrogen release fluxes were compared using in-situ and laboratory incubational examination. Sediment oxygen demands were 116, 34, and $31\;mmol\;O_2\;m^{-2}\;d^{-1}$ (in-situ incubation), 52, 17, and $15\;mmol\;O_2\;m^{-2}\;d^{-1}$ (Core incubation) and dissolved inorganic nitrogen release fluxes were 7.18, 7.98, and $1.78\;mmol\;m^{-2}\;d^{-1}$ (in-situ incubation), 3.33, 3.74, and $1.96\;mmol\;m^{-2}\;d^{-1}$ (Core incubation) at Tongyeong finfish, Yeosu finfish, and Wando abalone cage farms, respectively. Consequently, in-situ incubation results showed two times higher than laboratory examination. We compared the material flux at the sediment-water interface of each farm and the characteristics between two different kinds of material flux examination.

• Journal of the Korean Institute of Gas
• /
• v.23 no.6
• /
• pp.17-24
• /
• 2019

The combustion properties of the flammable substance used in industrial fields include lower/upper flash point, lower/upper explosion limit, autoignition temperature(AIT), fire point, and minimum oxygen concentration(MOC) etc.. The accurate assessment of these characteristics should be made for process and worker safety. In this study, tert-amylalcohol(TAA), which is widely used as a solvent for epoxy resins, oxidizers of olefins, fuel oils and biomass, was selected. The reason is that there are few researches on the reliability of combustion characteristics compared to other flammable materials. The flash point of the TAA was measured by Setaflash, Pensky-Martens, Tag, and Cleveland testers. And the AIT of the TAA was measured by ASTM 659E. The lower/upper explosion limits of the TAA was estimated using the measured lower/upper flash points by Setaflash tester. The flash point of the TAA by using Setaflash and Pensky-Martens closed-cup testers were experimented at 19 ℃ and 21 ℃, respectively. The flash points of the TAA by Tag and Cleveland open cup testers were experimented at 28 ℃ and 34 ℃, respectively. The AIT of the TAA was experimented at 437 ℃. The LEL and UEL calculated by using lower and upper flash point of Setaflash were calculated at 1.10 vol% and 11.95 vol%, respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.12 no.3
• /
• pp.179-189
• /
• 2014

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. An electrolytic reduction of the pyroprocessing is a process to reduce oxides into metals using LiCl as an electrolyte and requires a post-treatment process due to the inclusion of residual salt in porous metal products. A vacuum distillation has been adopted for various molten salt systems and could be applied to the post-treatment process of the electrolytic reduction. The residual salt in the metal products includes LiCl, alkali chlorides, and alkaline earth chlorides. In this paper, vapor pressures of chlorides have been estimated and the composition changes on the residual liquid during the vacuum distillation process have been calculated. A model combining a material balance and vapor-liquid equilibrium relations has been proposed under a constant vapor discharging flow rate and liquid composition changes have been calculated using the vapor pressures with respect to a dimensionless time. The behaviors have been compared with temperature and molten salt composition changes to simulate the process condition variation. The distillation of the residual salt has been dominated by LiCl which is the main component of the salt and CsCl of which vapor pressure is higher than that of LiCl would be readily removed. RbCl exhibits similar vapor pressure with LiCl and maintains its composition. However, $SrCl_2$ and $BaCl_2$ of which vapor pressures are much lower than that of LiCl are concentrated with time and expected to be possibly precipitated during the distillation when the initial compositions are increased.

• Journal of the Korean Institute of Gas
• /
• v.16 no.4
• /
• pp.38-43
• /
• 2012

The purpose of this study is to carry out the consequence analysis of an accident related to the release of Hydrogen chloride occurred in a petrochemical company in Korea and suggest the measures to prevent similar accidents from happening again. The total amount released through the safety valve of HCl Column was calculated based on the rated capacity of the safety valve, the ideal gas equation and mechanical energy balance, respectively. As a result of the calculation, we found that the amount of HCl released through the safety valve was at least 76.8 kg. Also, we predicted the dispersion concentration at the position of the injured workers(more than 350 m away from the accident location) using simulation programs such as PHAST. The results of ALOHA and K-CARM are 304 ppm and 1,700 ppm respectively. However, PHAST calculation indicated that the concentration is less than l ppm. From these results, we can understand that workers were injured by HCl gas released from the safe valve and the concentration of gas might be less than 1 ppm. Also, it is important for toxic gases such as HCl to be vented safely to the atmosphere after scrubbing.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.162-171
• /
• 1993

This paper deals with the anisotropy of the mushy region during solidification process of a binary mixture. A theoretical model which specifies a permeability tensor in terms of pricipal values is proposed. Also, the governing equations are modified into convenient forms for the numerical analysis with the existing algorithm. Some test computations are performed for soeidification of aqueous ammonium chloride solution contained in a square cavity. Results show that not only the present model is capable of resolving fundamental characteristics of the tranport phenomena, but also the anisotropy significantly affects the interdendritic flow structure, i.e., double-diffusive convection and macrosegregation patterns.

• Korean Chemical Engineering Research
• /
• v.55 no.1
• /
• pp.86-92
• /
• 2017

A process, which converts carbon dioxide contained in the flue gas of coal-fired power plants to sodium bicarbonate, was studied experimentally and numerically. In this process, the carbon dioxide reacts with sodium hydroxide which is produced through saline water electrolysis. A bench scale reactor system was prepared for experiments of this process and numerical process modeling was performed for the bench scale reactor system. Comparing the process modeling results with the experimental data, responsibility of the process modeling was confirmed. Using this model, commercial scale process was simulated. Mass and energy balance of this process were calculated. Temperature profile in the reactor and carbon dioxide removal rate were obtained.