• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.51-62
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• 2022

Metal-organic framework (MOF) is one of the representative porous materials composed of metal ions and organic linkers. In spite of many advantages of the MOFs such as high specific surface area and ease of structure control, drawbacks have become obstacles to the practical use of them with poor electrical conductivity and chemical stability. The ZIF-8, which is consisted of zinc and imidazole linker, is one of the solutions to improve the chemical stability issue. In addition, composites using the ZIF-8 and carbonbased materials are widely used to enhance the electrical conductivity. In this regard, supercapacitor is very attractive field for using the composites, because most of carbon-based materials are porous and conductive. Also, for sensor applications, the ZIF-8 composite is suitable material to meet the requirement in terms of the selectivity and sensitivity. This review summarizes recent progress of the composite materials with the ZIF-8 and the carbon-based materials for the supercapacitors and the chemical sensors. In particular, the composites are classified into ZIF-8-graphene, ZIF-8-carbon nanotube and ZIF-8-other carbon-based material.

• Geomechanics and Engineering
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• v.2 no.2
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• pp.141-156
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• 2010

In the framework of meshfree methods, a new methodology is developed based on radial point interpolation method (RPIM). This methodology is applied to a one-dimensional contaminant transport modelling in the saturated porous media. The one-dimensional form of advection-dispersion equation involving reactive contaminant is considered in the analysis. The Galerkin weak form of the governing equation is formulated using 1D meshfree shape functions constructed using thin plate spline radial basis functions. MATLAB code is developed to obtain the numerical solution. Numerical examples representing various phenomena, which occur during migration of contaminants, are presented to illustrate the applicability of the proposed method and the results are compared with those obtained from the analytical and finite element solutions. The proposed RPIM has generated results with no oscillations and they are insensitive to Peclet constraints. In order to test the practical applicability and performance of the RPIM, three case studies of contaminant transport through the landfill liners are presented. A good agreement is obtained between the results of the RPIM and the field investigation data.

• Smart Structures and Systems
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• v.26 no.4
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• pp.469-480
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• 2020

This is the first research on the smart control and vibration analysis of a Graphene nanoplatelets (GPLs) Reinforced Composite (GPLRC) porous cylindrical shell covered with piezoelectric layers as sensor and actuator (PLSA) in the framework of numerical based Generalized Differential Quadrature Method (GDQM). The stresses and strains are obtained using the First-order Shear Deformable Theory (FSDT). Rule of the mixture is employed to obtain varying mass density and Poisson's ratio, while the module of elasticity is computed by modified Halpin-Tsai model. The external voltage is applied to sensor layer and a Proportional-Derivative (PD) controller is used for sensor output control. Governing equations and boundary conditions of the GPLRC cylindrical shell are obtained by implementing Hamilton's principle. The results show that PD controller, length to radius ratio (L/R), applied voltage, porosity and weight fraction of GPL have significant influence on the frequency characteristics of a porous GPLRC cylindrical shell. Another important consequence is that at the lower value of the applied voltage, the influence of the smart controller on the frequency of the micro composite shell is much more significant in comparison with the higher ones.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1489-1495
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• 2010

A porous coordination solid of nickel(II) dihydroxyterephthalate has been synthesized by the microwave-assisted (MW) method. The synthesized nickel(II) dihyroxylterephthalate was designated by the general formula of [$Ni_2$(dhtp) $(H_2O)_2]{\cdot}8H_2O$ (where, dhtp = 2,5-dihydroxyterephthalate, denoted by Ni-DHTP). The effect of microwave-irradiation temperature and time of irradiation on the porosity and morphological changes in the solids have also been investigated. The catalytic performance of Ni-DHTP synthesized by MW method has been studied in the oxidation of cyclohexene with aqueous $H_2O_2$, which gave cyclohexene oxide as the primary product and 2-cyclohexene-1-ol as a major product.

• Korean Journal of Chemical Engineering
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• v.36 no.6
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• pp.975-980
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• 2019

Infrared (IR) spectroscopy is a powerful technique for observing organic molecules, as it combines sensitive vibrational excitations with a non-destructive probe. However, gaseous volatile compounds in the air are challenging to detect, as they are not easy to immobilize in a sensing device and give enough signal by themselves. In this study, we fabricated a thin nanocrystalline metal-organic framework (nMOF) film on a surface plasmon resonance (SPR) substrate to enhance the IR vibration signal of the gaseous volatile compounds captured within the nMOF pores. Specifically, we synthesized nanocrystalline HKUST-1 (nHKUST-1) particles of ca. 80 nm diameter and used a colloidal dispersion of these particles to fabricate nHKUST-1 films by a spin-coating process. After finding that benzene was readily adsorbed onto nHKUST-1, an nHKUST-1 film deposited on a plasmonic Au substrate was successfully applied to the IR detection of gaseous benzene in air using surface-enhanced IR spectroscopy.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2714-2719
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• 2022

The present paper proposes some new computational methods and results in the framework of flow computation through congested domains seen as porous media, as it can be found in the core of a Pressurized Water Reactor (PWR). The flow is thus mostly governed by the distribution of pressure losses, both through the porous structures, such as fuel assemblies, and in the thin fluid layers between them. The purpose of the present paper is to consider the question of the interaction of a flow and a rod bundle from an analytical point of view gathering all the contributions through a set of equations as simple and representative as possible. It aims at demonstrating a sound understanding of the relevant phenomena governing the flow establishment in the geometry of interest instead of relying mainly on a posteriori observations obtained both experimentally and numerically. Comparison with two set of experimental results showed good agreement. The model proposed being analytical it appears easily implementable for studies needing an expression of fluid forces in a rod array as for fuel assembly bowing issue. It would be interesting to test the reliability of the model on other geometry with different P/R ratios.

• Korean Journal of Materials Research
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• v.27 no.9
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• pp.466-470
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• 2017

With the matters of climate change, energy security and resource depletion, a growing pressure exists to search for replacements for fossil fuels. Among various sustainable energy sources, hydrogen is thought of as a clean energy, and thus efficient hydrogen storage is a major issue. In order to realize efficient and safe hydrogen storage, various porous materials are being explored as solid-states materials for hydrogen storage. For those purposes, it is a prerequisite to characterize a material's textural properties to evaluate its hydrogen storage performance. In general, the textural properties of porous materials are analyzed by the Brunauer-Emmett-Teller (BET) measurement using nitrogen gas as a probe molecule. However, nitrogen BET analysis is sometimes not suitable for materials possessing small pores and surfaces with high curvatures like MOFs because the nitrogen molecule may sometimes be too large to reach the entire porous framework, resulting in an erroneous value. Hence, a smaller probe molecule for BET measurements (such as hydrogen) may be required. In this study, we describe a cost-effective novel cryostat for BET measurement that can reach temperatures below the liquefaction of hydrogen gas. Temperature and cold volume of the cryostat are corrected, and all measurements are validated using a commercial device. In this way, direct observation of the hydrogen adsorption properties is possible, which can translate directly into the determination of textural properties.

• Steel and Composite Structures
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• v.42 no.6
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• pp.805-826
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• 2022

The free and live load-forced vibration behaviour of porous functionally graded (PFG) higher order nanobeams in the thermal and magnetic fields is investigated comprehensively through this work in the framework of nonlocal strain gradient theory (NLSGT). The porosity effects on the dynamic behaviour of FG nanobeams is investigated using four different porosity distribution models. These models are exploited; uniform, symmetrical, condensed upward, and condensed downward distributions. The material characteristics gradation in the thickness direction is estimated using the power-law. The magnetic field effect is incorporated using Maxwell's equations. The third order shear deformation beam theory is adopted to incorporate the shear deformation effect. The Hamilton principle is adopted to derive the coupled thermomagnetic dynamic equations of motion of the whole system and the associated boundary conditions. Navier method is used to derive the analytical solution of the governing equations. The developed methodology is verified and compared with the available results in the literature and good agreement is observed. Parametric studies are conducted to show effects of porosity parameter; porosity distribution, temperature rise, magnetic field intensity, material gradation index, non-classical parameters, and the applied moving load velocity on the vibration behavior of nanobeams. It has been showed that all the analyzed conditions have significant effects on the dynamic behavior of the nanobeams. Additionally, it has been observed that the negative effects of moving load, porosity and thermal load on the nanobeam dynamics can be reduced by the effect of the force induced from the directed magnetic field or can be kept within certain desired design limits by controlling the intensity of the magnetic field.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.200-203
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• 2011

A copper-based metal organic framework (MOF) named Cu-BTC, also known as HKUST-1, was synthesized by using a solvothermal method at various synthesis temperature, time and pressure. The obtained samples were characterized with Powder X-ray diffraction (XRD) for phase structure, scanning electron microscopy (SEM) for crystal structure, and nitrogen adsorption-desorption for pore textural structure. The Cu-BTC sample was also studied for $CO_2$ adsorption. The analysis results displayed that the sample synthesized at the condition of temperature: $120^{\circ}C$, synthesis time: 12 hours, pressure: 1 bar exhibited a good crystal structure with uniform size of octahedral particles. The BET data revealed a high surface area of 1741.7 $m^2g^{-1}$ and a pore volume of 0.7137 $cm^3g^{-1}$and exhibiteda maximum $CO_2$ adsorption capacity of 170 mg/g of the sorbent at $25^{\circ}C$.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.258-266
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• 2020

The chemical fixation of CO₂ into cyclic carbonates is considered to be one of the most promising way to alleviate global warming and produce fine chemicals. In this work, the catalytic applicability of metal-organic frameworks (MOFs) as porous crystalline materials for the synthesis of five-membered cyclic carbonate from CO₂ and epoxides was reviewed. In addition, we have briefly classified the materials based on their different structural features and compositions. The studies revealed that MOFs exhibited good catalytic performance towards cyclic carbonate synthesis because of the synergistic effect between the acid sites of MOFs and nucleophile. Moreover, the effect of structure of designed MOFs and mechanism for the cycloaddition of CO₂ were suggested.