• Tunnel and Underground Space
• /
• v.13 no.1
• /
• pp.20-32
• /
• 2003

To understand the behavior of migration of contaminants in a fractured porous medium is a key to assure the overall safety of a potential radwaste repository. The feasible retention mechanism of contaminant transport in a tinctured medium are sorption of contaminants on solid surface and matrix diffusion of contaminants from a fracture into an adjacent porous medium. The acceleration mechanisms are the migration of contaminants in the form of pseudo-colloids and the limit of a volume f3r matrix diffusion. In this paper, the effects of these two acceleration mechanisms are studied mathematically, then semi-analytically computed by the application of the Talbot theorem and verified. Results indicate that the acceleration processes cannot be neglected in the modeling of contaminant transport in a fractured porous medium.

• Cross-Cultural Studies
• /
• v.37
• /
• pp.7-29
• /
• 2014

The 'discovery' or 'conquest' of the New World in 1492 was the starting point of world history that irrevocably changed the fate of the Latin American continent. The global stream known as 'Columbian Exchange', which was the widespread inter-continental contacts, inter-civilizational conflicts, or bilateral communication, has rendered multifarious effects throughout many historical periods up to the very contemporary time. The propagation of Catholicism initiated along with this 'discovery' transformed Latin America of nowadays in the region that has the biggest Catholic population in the world. The previous studies in Korea regarding Latin American Catholicism has focused on the spread of Catholicism in relation to the European colonization, rather than analyzing the concrete and detailed ways in which Catholicism exerted tremendous influences in the whole continent. They were less attentive to various historical contexts in which the diffusion of Catholicism differed greatly according to cultural landscapes and political specificities. Thus, this essay attempts to examine the diffusion of Catholicism from the perspective of confrontation between royal authorities and the power of church. The essay points out that the royal communities and institutional authorities which facilitated the intial process of Catholic evangelization maintained antagonistic relationship with ecclesial powers. By delving into the gradual transformation of church systems, it reveals that Catholicism in Latin America became a major field for conquerors in power to attain economic and political dominance. And unlike the initial submission and hospitality, the religious convert of the indigenous people attested to the violent inhumanity and opposition. Therefore, the essay aims to pave a clearer way to the understanding of complicated dynamics and conflicts between Catholicism in Latin America and the establishment of Spanish colonization.

• KSBB Journal
• /
• v.14 no.1
• /
• pp.1-8
• /
• 1999

It confirmed the facilitated diffusion of $Na^+$ of frog bladder membrane which is a tissue membrane. The mechanism was explained in $Na^+$ channel model and its referred to the $Na^+$ channel obstruction ingredient which was contained in the reference to the $Na^+$ channel obstruction ingredient and son on, e.g., seaweed, shellfish, pufferfish, phytoplankton and chinese drug. Also, it introduces the result which studied from the barrier point of the application of the tissue biosensor to the trade friction on Korea or Japan pufferfish and the marine environment in the one with high dependance. It was possible for the poison quantity of small amount pufferfish toxin (TTX), paralytic shellfish poisoning (PSP) to be measured and also to measure poison quantity in the cultivation poisonous toxin phytoplankton individual. In future, as for this tissue biosensor, it expects that it is possible to contribute widely until environment watch and also monitoring to the scene.

• Journal of Environmental Science International
• /
• v.7 no.6
• /
• pp.773-782
• /
• 1998

The adsorption experiment of phenol(Ph) from aqueous solution on granular activated carbon was studied in order to design the fixed-bed adsorption column. The experimental data were analyzed by unsteady-state, one-dimensional heterogeneous model. Finite element method(FEM) was applied to analyze the sensitivity of parameter and to predict the fixed-bed adsorption column performance on operation variable changes. The prediction model showed similar effect to mass transfer and intraparticle diffusion coefficient changes suggesting that both parameter present mass transfer rate limits for GAC-phenol system. The Freundlich constants had a greater effect than kinetic parameters for the performance of fixed-bed adsorption column. FEM solution facilitated prediction of concentration history in solution and within adsorbent particle.

• Proceeding of EDISON Challenge
• /
• 2014.03a
• /
• pp.183-195
• /
• 2014

Kinetically constrained models (KCM) have attracted interest as models that assign dynamic origins to the interesting dynamic properties of supercooled liquid. Signs of dynamic heterogeneity in the crossover model that linearly interpolates between the FA-like symmetric constraint and the East model constraint by asymmetric parameter b were investigated using Monte Carlo technique. When the asymmetry parameter was decreased sufficiently, smooth fragile-to-strong dynamic transition was observed in terms of the relaxation time, diffusion constant, Stokes-Einstein violation, and dynamic length scale. Competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism is behind such transition.

• KSBB Journal
• /
• v.20 no.3
• /
• pp.133-141
• /
• 2005

This review presents the preparation, transport mechanism and application of molecularly imprinted membranes (MIM). Molecular imprinting has now been established as a technique which allows the creation of tailor-made binding sites for many classes of compounds. MIM have some advantages; a high capacity due to a large surface area, faster transport of substrate molecules and faster equilibrium of binding cavities compared to molecularly imprinted particles. MIM were prepared by covalent and non-covalent chemical bonding systems, by interactions between functional monomer and template. MIM can be prepared by in-situ polymerization, wet phase inversion, dry phase inversion, and surface imprinting method. MIM can continuously separate mixtures based on facilitated or retarded diffusion of the template. MIM can change their permeability in the presence of templates. MIM have a potential to be used to separate chiral compounds and materials with similar structures. However the application of MIM by the chemical industries is still in its infancy stages.

• Journal of Industrial and Engineering Chemistry
• /
• v.68
• /
• pp.140-145
• /
• 2018

Bulky carbon layer uniformly distributed with nanoscale $Fe_2O_3$ was prepared via a direct carbonation of $Fe^{3+}$-polyacrylonitrile complexes at $700^{\circ}C$ under $N_2$ flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ${\sim}810mAh\;g^{-1}$ after 250 cycles at a current rate of $100mA\;g^{-1}$. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active $Fe_2O_3$ during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.48 no.2
• /
• pp.300-311
• /
• 2024

Amid global environmental concerns, initiatives to adopt sustainable industrial processes have garnered significant attention in diverse sectors. Efforts have centered on utilizing natural resources as dyeing and functionalizing agents in the textile industry. However, the limited color fastness and functional endurance of natural compounds remains a substantial challenge. This research investigated whether ultrasound could enhance the finishing effect of natural compounds on cotton fabrics. Chestnut shell extract was prepared and applied to cotton fabrics using a pad-dry-cure technique, with concurrent application of ultrasonic power. Once integrated into the fabrics, the chestnut shell extract exhibited prolonged health benefits for users. The findings demonstrated that ultrasound treatment during the finishing process facilitated the diffusion of natural compounds from the chestnut shell extract into the fabric structure, resulting in a substantial enhancement of the finishing effect, notably augmenting the antibacterial properties of the treated cotton fabrics.

• Korean Journal of Chemical Engineering
• /
• v.35 no.12
• /
• pp.2384-2393
• /
• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.

• Membrane Journal
• /
• v.27 no.2
• /
• pp.167-181
• /
• 2017

Graphene-based materials have been considered as a promising membrane material, due to its easy processability and atomic thickness. In this study, we studied on gas permeation behavior in few-layered GO membranes prepared by spin-coating method. The GO membrane structures were varied by using different GO flake sizes and GO solutions at various pH levels. The GO membranes prepared small flake size show more permeable and selective gas separation properties than large one due to shortening tortuosity. Also gas transport behaviors of the GO membranes are sensitive to slit width for gas diffusion because the pore size of GO membranes ranged from molecular sieving to Knudsen diffusion area. In particular, due to the narrow pore size of GO membranes and highly $CO_2$-philic properties of GO nanosheets, few-layered GO membranes exhibit ultrafast and $CO_2$ selective character in comparison with other gas molecules, which lead to outstanding $CO_2$ capture properties such as $CO_2/H_2$, $CO_2/CH_4$, and $CO_2/N_2$. This unusual gas transport through multi-layered GO nanosheets can explain a unique transport mechanism followed by an adsorption-facilitated diffusion behavior (i.e., surface diffusion mechanism). These findings provide the great insights for designing $CO_2$-selective membrane materials and the practical guidelines for gas transports through slit-like pores and lamellar structures.