Numerical simulation of reverse electrodialysis with ammonium bicarbonate

A closed-loop reverse electrodialysis (RED) system using thermolytic solution has drawn significant attention in a low-grade waste heat energy recovery. The closed-loop characteristic enable the system have merits such as no need of repetitive pretreatment cost and removal of locational constraint than open-loop RED with sea and river water. In this study, we presents the numerical simulation of RED using ammonium bicarbonate which is one of the promising solute. The permselectivity of ion exchange membrane was calculated from membrane potential with various concentration ratios. We found that the polarization and the power density curve using the computed permselectivity are similar to the experimental results. The RED performance with ammonium bicarbonate was validated according to various concentration combination and flow rate. The open circuit voltage (OCV) and power density fit well for a wide range of solution concentration and the various flow rate. Finally, the optimum value of net power density, which consider the pumping loss, was obtained in terms of the intermembrane distance and the concentration ratio by the net power density contour. Please click Additional Files below to see the full abstract

Power Generation with Thermolytic Reverse Electrodialysis for Low-Grade Waste Heat Recovery

Closed-loop reverse electrodialysis (RED) systems that use a thermolytic solution for low-grade waste heat recovery have attracted significant attention. They have several cost benefits, e.g., the absence of repetitive pretreatment and removal of locational constraints, when compared with open-loop RED systems using seawater and river water. This study presents a model of RED that uses ammonium bicarbonate, and this is a promising solution for closed-loop systems. The modified Planck-Henderson equation is used to calculate the ion exchange membrane potential. The calculation is based on the conductivity measurements as ionization carbonate electrochemical information has not been reported before this study. The solution resistance is experimentally determined. The experimentally obtained permselectivity is implemented into the model to predict the membrane potential more accurately. The results of the improved model are well matched with experimental results under results under various operating conditions of the RED system. In addition, in the model of this study, the net power density was characterized with the consideration of the pumping loss. The improved model predicts a maximum net power density of 0.84 W/m2 with an intermembrane distance of 0.1 mm, a flow rate of 3 mL/min, and a concentration ratio of 200 as optimum conditions. The results of the study are expected to improve our understanding of the ammonium bicarbonate-RED system and contribute to modeling studies using ammonium bicarbonate or certain other compounds for novel technologies of waste heat recovery

Analysis of Long-Range Transport of Carbon Dioxide and Its High Concentration Events over East Asian Region Using GOSAT Data and GEOS-Chem Modeling

This study aims to evaluate the long-range transport of CO2 in East Asian region, using concentration data in a surface measurement site (Gosan Station), column averaged concentration data of satellite-borne instrument (GOSAT), and GEOS-Chem modeling results for the period of June 2009 to May 2011. We perform a validation of the data from GOSAT and GEOS-Chem with total column observations (TCCON). The analysis of the long-range transport and high concentration (HC) events using surface/satellite observations and modeling results is conducted. During the HC events, the concentrations in CO2 and other air pollutants such as SO2 and CO are higher than that of all episodes. It means that CO2, known as a globally well-mixed gas, may also act as a fingerprint of human activity with unique regional characteristics like other air pollutants. This comprehensive analysis, in particular with GOSAT CO2 observation data, shows that CO2 plume with high concentration can be long-range transported with 1-2 days' duration with regional scale. We can find out with GEOS-Chem tagging simulation that more than 45% of the elevated CO2 concentration over central/eastern China, Korea, and Japan on high concentration days can be explained by emission sources of East Asia mainland.open0

Change of Platelet Reactivity to Antiplatelet Therapy after Stenting Procedure for Cerebral Artery Stenosis: VerifyNow Antiplatelet Assay before and after Stenting

PurposeVerifyNow antiplatelet assays were performed before and after stenting for various cerebral artery stenoses to determine the effect of the procedure itself to the function of dual antiplatelets given.Materials and MethodsA total of 30 consecutive patients underwent cerebral arterial stenting procedure were enrolled. The antiplatelet pretreatment regimen was aspirin (100 mg daily) and clopidogrel (300 mg of loading dose followed by 75mg daily). VerifyNow antiplatelet assay performed before and right after stenting. The two test results were compared in terms of aspirin-reaction unit (ARU), P2Y12 reaction units (PRU), baseline (BASE), and percentage inhibition. We evaluated occurrence of any intra-procedural in-stent thrombosis or immediate thromboembolic complication, and ischemic events in 1-month follow-up.ResultsThe median Pre-ARU was 418 (range, 350-586). For clopidogrel the medians of the pre-BASE, PRU, and percent inhibition were 338 (279-454), 256 (56-325), and 27% (0-57%). The medians of the post-ARU, BASE, PRU, and percent inhibition after stenting were 469 (range, 389-573), 378 (288-453), 274 (81-370), and 26% (0-79%). There was a significant increase of ARU (p=0.045), BASE (p=0.026), and PRU (p=0.018) before and after stenting. One immediate thromboembolic event was observed in poor-response group after stenting. There was no in-stent thrombosis and ischemic event in 1-month follow-up.ConclusionWe observed a significant increase of platelet reactivity to dual antiplatelet therapy right after stenting procedure for various cerebral arterial stenoses

Effectiveness of a Virtual Reality Head-Mounted Display System-based Developmental Eye Movement Test

By transplanting the Developmental Eye Movement (DEM) test chart to a virtual reality head-mounted display (VR HMD) system, this study sought to evaluate the effectiveness of the DEM test for measuring dynamic visual acuity.Thirty-nine adults aged 20–39 years of both genders were the subjects of the study. After undergoing measurement of their visual function, through medical questionnaire, interpupillary distance, near point of convergence (NPC), near point of accommodation (NPA), and far and near phoria, the correlation between the tests was analyzed performing DEM vertical, horizontal test and VR HMD DEM (VHD) vertical, horizontal test.NPC and NPA decreased significantly after the VHD test, while phoria did not. The horizontal was quicker than the vertical in the DEM test, and vice versa in the VHD test. DEM was quicker than VHD in both the vertical and horizontal directions. There was no notable difference in error frequency between DEM and VHD. In terms of DEM and VHD test, there was no notable difference in the short-range IPD and subjective symptoms of the top 10 and bottom 10 subjects. There was also no notable difference between the exercise and non-exercise groups and the game and non-game groups.The performance time for VHD, in which the chart must be read while moving the body, was longer than that of DEM. Therefore, based on the consistency of the results of both tests and the lack of a difference in error frequency and subjective symptoms, the VHD equipment proposed in this thesis is as effective as dynamic visual acuity measurement equipment. In addition, the lack of a difference between the exercise and non-exercise groups and the game and non-game groups demonstrated that the amount of exercise and game by an ordinary person does not influence their dynamic visual function

Institutional Change and Continuity in Koreas Central Agencies, 1948-2011

This article analyzes Koreas central agencies, which have been organized and reorganized to support presidential executive leadership since the foundation of the Republic. Each central agency has carried out the standardization of a core administrative function which is essential to the operation of administrative apparatuses, including policy planning and coordination, budgeting, organizing, staffing, legislation, public relations, central-local relations, control and performance evaluation, etc. The six decades of institutionalization can be characterized, based on the central agencies proportion of the total administrative apparatus, into three phases: high (more than 35 percent, 1948-1961), middle (around 20 percent, 1962-2007), and low (about 10 percent, 2008-present). Regardless of the changing size and organizational configuration of the central agencies, however, their roles and influence as core executive apparatuses have remained largely unchanged, especially since the early 1960s. More than 67 percent, on average, of the heads and deputy heads of CAs have been former public servants, less than 18 percent have been former politicians, and about 15percent have been former outside experts. This strong bureaucratic background has oriented Koreas core executive policy direction significantly toward longterm, consistent, and plan rationality rather than short-term, flexible, and democratic responsiveness