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Operation of a free piston linear engine is modeled based on the combination of three mathematical models, including a piston dynamic model, a linear alternator model and a thermodynamic model. The simulated in-cylinder pressure, piston velocity, and electric power output are compared with the corresponding experimental results to validate the models mentioned above. The influences of the design parameters, including cylinder dimension ( Le), number of coil turns ( N), and air gap ( g) between the translator and stator, on the dynamic performance, in-cylinder pressure and electric power generation of the free piston linear engine are studied. The study results show that the reduction of Le has a benefit for improving the piston dynamic performance and output electric power, however it also reduced the cylinder pressure. The increase of number of coil turns N results in the reduction of the peak piston velocity, displacement, acceleration, and pressure in the cylinder, however, it increases the output electric power of the free piston linear engine. The peak piston velocity, displacement, acceleration, and pressure in the cylinder are considerably decreased when g is reduced. However, the reduction of g has a benefit to improve the output electric power of the free piston linear engine. The energy conversion efficiency can be maximized when g and Le are reduced, and N is increased.

In general, the dropwise condensation supported by superhydrophobic surfaces results in enhanced heat transfer relative to condensation on normal surfaces. However, in supersaturated environments that exceed a certain supersaturation threshold, moisture penetrates the surface structures and results in attached condensation, which reduces the condensation heat transfer efficiency. Therefore, when designing superhydrophobic surfaces for condensers, the surface structure must be resistant to attached condensation in supersaturated conditions. The gap size and complexity of the micro/nanoscale surface structure are the main factors that can be controlled to maintain water repellency in supersaturated environments. In this study, the condensation heat exchange performance was characterized for three different superhydrophobic titanium surface structures via droplet behavior (DB) mapping to evaluate their suitability for power plant condensers. In addition, it was demonstrated that increasing the surface structure complexity increases the versatility of the titanium surfaces by extending the window for improved heat exchange performance. This study demonstrates the usefulness of DB mapping for evaluating the performance of superhydrophobic surfaces regarding their applicability for industrial condenser systems.

Abstract - Solutions to improve collaborative energy-saving programs were developed as follow; First, the scoring for the selection of the programs between KEMCO and the NGOs' Energy Network needs to be adjusted. Second, solutions were proposed to diversify the network selected to participate in programs and to tighten the network among the participating citizens. Third, improving the compatibility with the targets that are set for the program and raising the program budget was proposed. Fourth, ideas to introduce the final evaluation guidelines for the programs by the network, to improve the convenience of the program procedures. Fifth, developing a manual to inspect energy-saving measures in households, counseling for at-home energy-saving behaviors, sharing search programs such as financial support and home repair, introducing a program energy-saving APPs. Key words : energy conservation, NGO, collaborative projects, improvements 1. 서 론 정부는 각종 에너지절약 홍보를 위한 행사를 개최하고 민간단체와의 협력체계를 강화하는 등 에너지절약 의식고취 및 에너지소비절약 생활화를 유도하기 위한 목적으로 에너지절약을 위한 시민단체 협력사업을 전개해 왔다. 이러한 정부의 에너지절약 시민단체 협력사업은 1994년부터 여성단체, 교육･연수기관 등을 에너지절약 협력단체로 선정하여 각 단체별로 자

Abstract In this study, a new type of plasma-burner reformer was proposed to convert methane or biogas into high-quality energy. The novel reformer is a combined technology as a plasma combustor and a matrix burner. The sequential mechanism of in-line plasma-burner reformer can improve POX reforming in the higher hydrogen-rich gas production. In order to present the performance potential for the novel PBR, the characteristics of conversion and product gases were identified according to the O2/C ratio, total feed gas, CO2: CH4 ratio, and recirculation of reformed gas, and the results are as follows: The reforming characteristics for each variable were identified, and the optimal operating condition of the PMBR was O2/C ratio of 1.0 and total feed gas of 20 L/min. At this time, CH4 conversion was 64%, H2 selectivity was 39%, and H2/CO ratio was 1.13, which were the results applicable to the SOFC fuel cell stack for RPG (Residential Power Generator). Recirculation of reformed gas increased the amount of hydrogen and carbon monoxide, which are combustible gases, especially the amount of hydrogen. As a result, the hydrogen selectivity is improved, and high-quality gas can be produced.

From the PSA point of view, the Fukushima accident of Japan in 2011 reveals some issues to be re-considered and/or improved in the PSA such as the limited scope of the PSA, site risk, etc. KAERI (Korea Atomic Energy Research Institute) has performed researches on the development of an integrated risk assessment framework related to some issues arisen after the Fukushima accident. This framework can cover the internal PSA model and external PSA models (fire, flooding, and seismic PSA models) in the full power and the low power-shutdown modes. This framework also integrates level 1, 2 and 3 PSA to quantify the risk of nuclear facilities more efficiently and consistently. We expect that this framework will be helpful to resolve the issue regarding the limited scope of PSA and to reduce some inconsistencies that might exist between (1) the internal and external PSA, and (2) full power mode PSA and low power-shutdown PSA models. In addition, KAERI is starting researches related to the extreme external events, the risk assessment of spent fuel pool, and the site risk. These emerging issues will be incorporated into the integrated risk assessment framework. In this paper the integrated risk assessment framework and the research activities on the emerging issues are outlined.

Energy depletion for the thermal regulation of buildings is a major global concern. Herein, we develop a binary eutectic phase change material (EPCM) consisting of sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) that were modified using borax, carboxymethyl cellulose (CMC), and graphene nanoplatelets (GNP). In the EPCM, SSD, and SPDD were blended at a proportion of 62:38 to obtain a eutectic point of 27.8 °C with a melting enthalpy of 202 J/g. Borax was a nucleating additive to lessen the issue of supercooling, CMC was a thickening agent to ensure phase stability, and GNP was added as a nanomaterial to enhance the thermal behavior of EPCM. Microtopography, chemical stability, optical transmissibility and absorptivity, phase transition characteristic, thermal conductivity, energy storage potential, degree of supercooling, and thermal stability over 200 thermal cycles were tested and determined. Using scanning electron microscopy, the GNP microstructure and its interaction with EPCM are visualized to present the dispersion and formation of the thermal network. The nanocomposite EPCM also has chemical stability, which is aided by a 571% increase in optical absorbance and an 83.8% decrease in transmissibility. With GNP as a nanomaterial, owing to the well-developed thermal network, we achieve a 106% increment in thermal conductance from 0.464 W/m⋅K to 0.956 W/m⋅K; likewise, GNP acts as a conducting binder and enhances the intermolecular interaction leading to an increase in melting enthalpy from 202.4 J/g to 226 J/g. Finally, a numerical simulation of EPCM heating a thermic fluid flowing within a concentric tube with focus on the temperature contour is conducted for elaborating the potential of PCM towards TES systems.

The leaves of three Ligularia species belonging to the family Compositae, Ligularia stenocephala, L. fischeri, and L. fischeri var. spiciformis, were qualitatively and quantitatively analyzed on the caffeoylquinic acids by HPLC and subjected to peroxynitrite-scavenging assay. The IC(50) of the MeOH extract of L. stenocephala was 1.62+/-0.03 mug/ml and the major caffeoylquinic acids of L. stenocephala were 5-O-caffeoylquinic acid, 3,5-di-O-caffeoyl-muco-quinic acid, and 3,5-di-O-caffeoylquinic acid. The compositions of caffeoylquinic acids were different for the three plants. Since percentage of total caffeoylquinic acids of the extract was highest (42.20% of the MeOH extract and 94.52% of the BuOH extract) in L. stenocephala and potent in peroxynitrite-scavenging assay, the extracts of L. stenocephala were chosen to perform in vivo anti-ulcerogenic activity. Treatment of mice with the MeOH- and BuOH extracts decreased the diameter of gastric lesions caused by HCl/ethanol- and indomethacin/bethanechol and decreased the volume of gastric juice, suggesting that caffeoylquinic acids have anti-ulcerogenic activity. These results suggest that the leaves of Ligularia species may help prevent or treat gastric ulcers.

AbstractImproving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis.