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Smart grids have attracted increasing interest in the field of industrial research. These systems allow electricity consumers to communicate with electrical systems using bidirectional communications. However, these bidirectional channels may introduce privacy threats to consumers. Considerable research has been conducted with the aim of resolving these threats. Unfortunately, a practical smart grid design with adequate efficiency and security functionalities has not yet been produced. In this paper, we propose lightweight privacy preserving metering protocols by designing a distributed authentication method to further increase the speed of the message authentication process. We confirmed the efficiency and security of our method by performing a detailed analysis.

As the first invention to efficiently harvest electricity from ambient mechanical energy by using contact electrification, the triboelectric nanogenerator has elicited worldwide attention because of its cost-effectiveness and sustainability. This study exploits a superhydrophobic nanostructured aluminum tube to estimate electrical output for solid-water contact electrification inside a tubular system. The linearly proportional relationship of short-circuit current and open-circuit voltage to the detaching speed of water was determined by using a theoretical energy harvesting model and experimentation. A pioneering stick-type solid-water interacting triboelectric nanogenerator, called a SWING stick, was developed to harvest mechanical energy through solid-water contact electrification generated when the device is shaken by hand. The electrical output generated by various kinds of water from the environment was also measured to demonstrate the concept of the SWING stick as a compact triboelectric nanogenerator. Several SWING sticks were connected to show the feasibility of the device as a portable and compact source of direct power. The developed energy harvesting model and the SWING stick can provide a guideline for the design parameters to attain a desired electrical output; therefore, this study can significantly increase the applicability of a water-driven triboelectric nanogenerator.

Abstract Experiments on high pressure steam condensation inside a nearly horizontal tube were performed for application into Passive Auxiliary Feedwater System (PAFS) of Advanced Power Reactor Plus (APR+). At KAIST, a Single-tube COndensation experiment facility of PAFS (SCOP) was constructed. The one-through type open loop test, where steam circulation is driven by pressure difference between the steam generator and the venting valve, was conducted in order to compensate for insufficiency of the heater power. We found out that the open loop test produced the same condensation heat transfer coefficients as those of the closed loop within 1% difference. Using the open loop, we were able to generate the higher steam flow rate by three times than that done by the heater power. Sensitivity studies were performed to validate the heat transfer performance of the PAFS in regard to the pressure effect, the diameter effect and the angle effect. The operating range of experiments are 1–7 MPa (pressure), 50.4 mm (reference tube) and 33.4 mm (comparing tube) (tube outer diameter) and 2–4° (tube angle). The comparing tube gave 30% higher heat transfer coefficients over the reference tube. In our tests, the slug flow was not observed. Compared with the reference case with the inclined angle of 3°, the case with the inclined angle of 2° showed just a bit lower heat capacity without any transition into slug flow.

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.

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.