Process Integration of a Gas to Liquid Plant and a Power Plant

The gas-to-liquid (GTL) industry is vulnerable to the variation of the oil and gas market price. This shortcoming has forced future GTL projects to be suspended and even cancelled. As one of the measures to overcome the challenge the GTL industry faces, process integration of a GTL plant and a power plant via a F-T tail gas supply line is proposed. The process integration allows an integrated plant to adjust F-T tail gas distribution that affects the production rates of two products, oil and electricity. The first result shows that recycling F-T tail gas to the GTL plant is superior to supplying tail gas to the power plant in the perspectives of power generation and utility consumption. However, recycling all F-T tail gas to the GTL plant is not feasible due to the constraints that both plants require. One constraint is the requirement to reduce nitrogen compound build up in F-T tail gas, whereas the other constraint is the limitation of modified wobbe index range from gas turbine fuel specification. Since the latter constraint covers the former constraint, the modified wobbe index limitation governs the allowable range of F-T tail gas fraction. Despite the constraints, the integrated plant still has the flexibility on the adjustment of tail gas distribution. Within the feasible region, the integrated plant can be designed and operated by balancing multiple parameters including power generation, utility consumption and nitrogen compound buildup that have a trade-off relationship

Process Integration of a Gas to Liquid Plant and a Power Plant

The gas-to-liquid (GTL) industry is vulnerable to the variation of the oil and gas market price. This shortcoming has forced future GTL projects to be suspended and even cancelled. As one of the measures to overcome the challenge the GTL industry faces, process integration of a GTL plant and a power plant via a F-T tail gas supply line is proposed. The process integration allows an integrated plant to adjust F-T tail gas distribution that affects the production rates of two products, oil and electricity. The first result shows that recycling F-T tail gas to the GTL plant is superior to supplying tail gas to the power plant in the perspectives of power generation and utility consumption. However, recycling all F-T tail gas to the GTL plant is not feasible due to the constraints that both plants require. One constraint is the requirement to reduce nitrogen compound build up in F-T tail gas, whereas the other constraint is the limitation of modified wobbe index range from gas turbine fuel specification. Since the latter constraint covers the former constraint, the modified wobbe index limitation governs the allowable range of F-T tail gas fraction. Despite the constraints, the integrated plant still has the flexibility on the adjustment of tail gas distribution. Within the feasible region, the integrated plant can be designed and operated by balancing multiple parameters including power generation, utility consumption and nitrogen compound buildup that have a trade-off relationship

A STUDY ON THE INITIAL CHARACTERISTICS OF DOMESTIC SPENT NUCLEAR FUELS FOR LONG TERM DRY STORAGE

During the last three decades, South Korean nuclear power plants have discharged about 5,950 tons of spent fuel and the maximum bum-up reached 55 GWd/MTU in 2002. This study was performed to support the development of Korean dry spent fuel storage alternatives. First, we chose V5H-17 × 17 and KSFA-16 × 16 as representative domestic spent fuels, considering current accumulation and the future generation of the spent fuels. Examination reveals that their average burn-ups have already increased from 33 to 51 GWd/MTU and from 34.8 to 48.5 GWd/MTU, respectively. Evaluation of the fuel characteristics shows that at the average burn-up of 42 GWd/MTU, the oxide thickness, hydrogen content, and hoop stress ranged from 30 ∼ 60 μm, 250 ∼ 500 ppm, and 50 ∼ 75 MPa, respectively. But when burn-up exceeds 55 GWd/MTU, those characteristics can increase up to 100 μm, 800 ppm, and 120 MPa, respectively, depending on the power history. These results demonstrate that most Korean spent nuclear fuels are expected to remain within safe bounds during long-term dry storage, however, the excessive hoop stress and hydrogen concentration may trigger the degradation of the spent fuel integrity early during the long-term dry storage in the case of high burn-up spent fuels exceeding 45 GWd/MTU

REVIEW OF SPENT FUEL INTEGRITY EVALUATION FOR DRY STORAGE

Among the several options to solve PWR spent fuel accumulation problem in Korea, the dry storage method could be the most realistic and applicable solution in the near future. As the basic objectives of dry storage are to prevent a gross rupture of spent fuel during operation and to keep its retrievability until transportation, at the same time the importance of a spent fuel integrity evaluation that can estimate its condition at the final stage of dry storage is very high. According to the national need and technology progress, two representative nations of spent fuel dry storage, the USA and Japan, have established different system temperature criteria, which is the only controllable factor in a dry storage system. However, there are no technical criteria for this evaluation in Korea yet, it is necessary to review the previously well-organized methodologies of advanced countries and to set up our own domestic evaluation direction due to the nation's need for dry storage. To satisfy this necessity, building a domestic spent fuel test database should be the first step. Based on those data, it is highly recommended to compare domestic data range with foreign results, to build our own criteria, and to expand on evaluation work into recently issued integrity problems by using a comprehensive integrity evaluation code

Polymer-based interconnection cables to integrate with flexible penetrating microelectrode arrays

There have been various types of interconnection methods for neural interfacing electrodes, such as silicon ribbon cables, wire bonding and polymer-based cables. In this study, interconnection cables were developed for integration with a Flexible Penetrating Microelectrode Array (FPMA) that was previously developed for neural signal recording or stimulation. Polyimide and parylene C were selected as base materials for the interconnection cables as both materials can preserve the flexibility of the FPMA better than other interconnection methods such as silicon ribbon cable or wire bonding. We conducted durability tests to determine if the interconnection cables were suitable for in-vivo implantation, by long-term soaking of the cables in phosphate buffered saline solution. We measured the changes in impedance over time, and equivalent circuit models were used to analyze the electrochemical phenomena on the surface of the cables. Lastly, we implanted the cable-integrated electrodes device onto rabbit’s sciatic nerve and recorded neural signals to prove the feasibility of the developed FPMA integration system. © 2017, Springer Science+Business Media, LLC.1

The Regeneration of Large-Sized and Vascularized Adipose Tissue Using a Tailored Elastic Scaffold and dECM Hydrogels

A dome-shaped elastic poly(l-lactide-co-caprolactone) (PLCL) scaffold with a channel and pore structure was fabricated by a combinative method of 3D printing technology and the gel pressing method (13 mm in diameter and 6.5 mm in thickness) for patient-specific regeneration. The PLCL scaffold was combined with adipose decellularized extracellular matrix (adECM) and heart decellularized extracellular matrix (hdECM) hydrogels and human adipose-derived stem cells (hADSCs) to promote adipogenesis and angiogenesis. These scaffolds had mechanical properties similar to those of native adipose tissue for improved tissue regeneration. The results of the in vitro real-time PCR showed that the dECM hydrogel mixture induces adipogenesis. In addition, the in vivo study at 12 weeks demonstrated that the tissue-engineered PLCL scaffolds containing the hydrogel mixture (hdECM/adECM (80:20)) and hADSCs promoted angiogenesis and adipose tissue formation, and suppressed apoptosis. Therefore, we expect that our constructs will be clinically applicable as material for the regeneration of patient-specific large-sized adipose tissue

A Statistical Performance Analysis of Named Data Ultra Dense Networks

Named data networking (NDN) is a novel communication paradigm that employs names rather than references to the location of the content. It exploits in-network caching among different nodes in a network to provide the fast delivery of content. Thus, it reduces the backhaul traffic on the original producer and also eliminates the need for a stable connection between the source (consumer) and destination (producer). However, a bottleneck or congestion may still occur in very crowded areas, such as shopping malls, concerts, or stadiums, where thousands of users are requesting information from a device that resides at the edge of the network. This paper provides an analysis of content delivery in terms of the interest satisfaction rate (ISR) in ultra-dense network traffic situations and presents a final and an adequate statistical model based on multiple linear regression (MLR) to enhance ISR. A four-way factorial design was used to generate the dataset by performing simulations in ndnSIM. The results show that there is no significant interaction between four predictors: number of nodes (NN), number of interests (NI) per second, router bandwidth (RB), and router delay (RD). Moreover, the NI has a negative effect, and log(RB) has a positive effect on the ISR. The NN less than 10 has a significantly higher effect on the ISR compared with other nodes’ densities

Functional Characterization of Allelic Variations of Human Cytochrome P450 2C8 (V181I, I244V, I331T, and L361F)

The human cytochrome P450 2C8 is responsible for the metabolism of various clinical drugs as well as endogenous fatty acids. Allelic variations can significantly influence the metabolic outcomes. In this study, we characterize the functional effects of four nonsynonymous single nucleotide polymorphisms *15, *16, *17, and *18 alleles recently identified in cytochrome P450 2C8. The recombinant allelic variant enzymes V181I, I244V, I331T, and L361F were successfully expressed in Escherichia coli and purified. The steady-state kinetic analysis of paclitaxel 6-hydroxylation revealed a significant reduction in the catalytic activities of the V181I, I244V, and L361F variants. The calculated catalytic efficiency (kcat/Km) of these variants was 5–26% of that of the wild-type enzyme. The reduced activities were due to both decreased kcat values and increased Km values of the variants. The epoxidation of arachidonic acid by the variants was analyzed. The L361F variant only exhibited 4–6% of the wild-type catalytic efficiency in ω-9- and ω-6-epoxidation reactions to produce 11,12-epoxyeicosatrienoic acid (EET) and 14,15-EET, respectively. These reductions were mainly due to a decrease in the kcat value of the L361F variant. The binding titration analysis of paclitaxel and arachidonic acid showed that all variants had similar affinities to those of the wild-type (10–14 μM for paclitaxel and 20–49 μM for arachidonic acid). The constructed paclitaxel docking model of the variant enzyme suggests that the L361F substitution leads to the incorrect orientation of paclitaxel in the active site, with the 6′C of paclitaxel displaced from the productive catalytic location. This study suggests that individuals carrying the newly identified P450 2C8 allelic variations are likely to have an altered metabolism of clinical medicines and production of fatty acid-derived signal molecules