• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.66-74
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• 2014

In this paper, the performance of Hybrid Dimming control system for Daylighting system is evaluated by accredited tests. The system controls the balance of illuminance of daylight between daylight system and LED light system. It makes the normal illuminance of interior without the effects of weather by controlling the LED depending on the brightness of outside. For the tests, 6 diffusers($600{\times}300mm$) were installed in lighting area($36m^2$) and normal operation of the system sensors were tested about the interference of sunlight. The results of the examinations were satisfied with the criteria of accredited tests. Further research is the verification of energy saving effect by comparing the Hybrid Dimming control system to current artificial light system.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.273-281
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• 2022

The effect of addition of Cu on the localized corrosion performance of aged duplex stainless steel in chloride media has yet to be explained in a consistent manner, and there is some controversy in the literature regarding the composition of stainless steel and the experimental conditions (pH, temperature, chloride concentration, etc.) used. In this work, the effect of the addition of Cu on the microstructure, hardness, and corrosion resistance of duplex stainless steel in an acidic chloride or high concentration sulfuric acid solutions was investigated for annealed and aged alloys. The Cu addition of annealed duplex stainless steel strengthened the alloy and reduced the ferrite contents of the alloy, and it also increased the polarization behavior in chloride or sulfuric solutions, except for the case of a high potential in acidic chloride solution. However, the Cu addition of aged duplex stainless steel reduced the formation of harmful phases such as sigma and kai and increased the polarization behavior in acidic chloride or sulfuric solutions up to 0.8 wt% of the Cu content, after which it slightly decreased at 0.8 wt% Cu or more.

• Composites Research
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• v.31 no.2
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• pp.57-62
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• 2018

Interfacial and mechanical properties of neat and two sizing agents coated glass fiber (GF)/polydicyclopentadiene (p-DCPD) composites were evaluated at room and low temperatures, $25^{\circ}C$ and $-20^{\circ}C$. Sizing agents of GFs were extracted using acetone and compared via FT-IR. Surface energy and work of adhesion between GFs and p-DCPD were calculated by dynamic contact angle measurement. Mechanical properties of different GFs were determined using single fiber tensile test and interfacial properties of single GF reinforced DCPD strip were determined using cyclic loading tensile test. Mechanical properties of GFs/p-DCPD composites at room and low temperatures were determined using tensile, compressive, and Izod impact tests. Interfacial and mechanical properties were different with sizing agents of GFs and the optimized condition of sizing agent was found.

• Composites Research
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• v.29 no.6
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• pp.408-413
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• 2016

Commonly-used polymers are manufactured as versatile forms. Furthermore, continuous polymer fibers are recently manufactured using nylon or aramid fiber. One of common epoxy was also used to make polymer fibers. Bisphenol-A type was used as base epoxy whereas amine and anhydride were used as hardeners. Epoxy fibers was cured by stepping up the temperature to maintain the shape of epoxy fiber. Surface energy was measured to confirm the degree of interfacial adhesion by modified static contact angle method. After mechanical properties were measured via fiber tensile test, the evaluation of fiber fracture was proceeded. Tensile strength of epoxy fiber using amine type hardener was higher as 138 MPa than anhydride case as 70 MPa. Fractured surface exhibited different failure patterns at the cross-section.

• Journal of Adhesion and Interface
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• v.19 no.1
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• pp.13-18
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• 2018

At ruthenium (Ru) catalyst was exposed from the atmosphere, the degree of catalyst activation decreased. The change of catalyst activity with the number of days of exposure to air for the Ru catalyst was confirmed using the surface tension method quantitatively. Mechanical properties and surfactant change after polymerization by DCPD using Ru catalyst for each air exposure day was evaluated. The Ru catalyst mixed with a dilution agent was exposed in the air and color was monitored for each day. Surface tension was measured using Wilhelmy and PTFE and associated with different catalyst activities. Heat was measured in real time during polymerizing DCPD with Ru catalyst. After polymerization, tensile strength was measured for p-DCPD and the change of material property was measured. Interfacial properties were also evaluated via microdroplet pull-out tests between glass fiber and p-DCPD. The surface tension was stable until the 4 days (33 dyne/cm) whereas the surface energy increased at the 10 days (34 dyne/cm), which could be correlated with oxidation of the catalyst. Tensile property and interfacial shear strength (IFSS) was also stable until the 4 days (tensile strength: 38 MPa and IFSS: 26 MPa) whereas the mechanical property decrease at 10 days (tensile strength: 15 MPa and IFSS: 3 MPa) dramatically.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.313-320
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• 2019

In this study, cobalt diselenide ($CoSe_2$) and the composites ($CoSe_2@RGO$) of $CoSe_2$ and reduced graphene oxide (RGO) were synthesized by a facile hydrothermal reaction using cobalt ions and selenide source with or without graphene oxide (GO). The formation of $CoSe_2@RGO$ composites was identified by analysis with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). Electrochemical analyses demonstrated that the $CoSe_2@RGO$ composites have excellent catalytic activity for the reduction of $I_3{^-}$, possibly indicating a synergetic effect of $CoSe_2$ and RGO. As a consequence, the $CoSe_2@RGO$ composites were applied as a counter electrode in DSSC for the reduction of redox couple electrolyte, and exhibiting the comparable power conversion efficiency (7.01%) to the rare metal platinum (Pt) based photovoltaic device (6.77%).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2496-2512
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• 2021

The requirements for powerful computing capability, high capacity, low latency and low energy consumption of emerging services, pose severe challenges to the fifth-generation (5G) network. As a promising paradigm, mobile edge networks can provide services in proximity to users by deploying computing components and cache at the edge, which can effectively decrease service delay. However, the coexistence of heterogeneous services and the sharing of limited resources lead to the competition between various services for multiple resources. This paper considers two typical heterogeneous services: computing services and content delivery services, in order to properly configure resources, it is crucial to develop an effective offloading and caching strategies. Considering the high energy consumption of 5G base stations, this paper considers the hybrid energy supply model of traditional power grid and green energy. Therefore, it is necessary to design a reasonable association mechanism which can allocate more service load to base stations rich in green energy to improve the utilization of green energy. This paper formed the joint optimization problem of computing offloading, caching and resource allocation for heterogeneous services with the objective of minimizing the on-grid power consumption under the constraints of limited resources and QoS guarantee. Since the joint optimization problem is a mixed integer nonlinear programming problem that is impossible to solve, this paper uses deep reinforcement learning method to learn the optimal strategy through a lot of training. Extensive simulation experiments show that compared with other schemes, the proposed scheme can allocate resources to heterogeneous service according to the green energy distribution which can effectively reduce the traditional energy consumption.

• STI Policy Review
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• v.1 no.1
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• pp.23-42
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• 2010

The American Recovery and Reinvestment Act (ARRA), known widely as the "stimulus" bill, developed by the U.S. Congress and President-elect Obama in late 2008 and early 2009, is investing a significant portion of its $787 billion infusion of funds in future-oriented programs intended not only to "jump-start" the stalled American economy, but to promote the development of renewable energy sources and increase energy efficiency in appliances, buildings, transportation, and other sectors of the economy. These investments are expected both to create immediate employment in green industries and to build a more sustainable society in the long term. The Obama Administration's green energy initiatives are part of a larger emphasis on science and technology within its agenda. It has roots in the Obama campaign and is supported by an unusually strong science and technology team. Much of the activity is centered in the Department of Energy, which received a huge one-time increase in its fiscal year 2009 budget to support the new and expanded programs. Areas that have been neglected by the federal government R&D program for many years, including smart grid technology, solar, wind, and geothermal energy, received large boosts. Many of these programs - and, in fact, the broader concept of government involvement in commercial innovation - are politically controversial Previous attempts to expand research in these areas by liberal Democratic administrations and Congresses have been criticized and sometimes thwarted by conservatives. Whether President Obama's efforts will meet with more success, both politically and technologically, remains to be seen.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.2
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• pp.177-182
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• 2011

This study was designed to evaluate the effect of Yukwa prepared by addition of green tea powder on change of lipid composition and body weight in mouse model. Mice were fed with Yukwa containing the five different types of green tea powders such as Bucho-cha, Okro-cha, Yongjeong-cha, Oolong-cha and Hong-cha with a normal diet. Body weight changes of Yukwa fed mice were measured once in a week for seven weeks. After seven weeks, mice were sacrificed and serum and tissues were collected for the following: adipose tissue weight, liver morphology, adipose tissue size and cholesterol content. The Yukwa combination with green tea fed mice reduced all the parameters compared to Yukwa alone fed mice. In conclusion combination with green tea showed reducing effect of hypocholesterolemia, which suggests the possibility of application to green tea as a food ingredient.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3405-3410
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• 2011

We have investigated the cytotoxic potential of tellurium (Te) nanowires in BALB/3T3 fibroblast cells. Te nanowires were synthesized through an aqueous phase surfactant assisted method. Toxicological experiments, such as analysis of morphological changes, MTT assay, DAPI staining, and estimation of intracellular reactive oxygen species, were carried out to reveal the cytotoxic effects of Te nanowires. Te nanowires were found to be cytotoxic at all concentrations tested, in a dose-dependent manner. The UV/Vis spectra of Te nanowires suspended in a culture medium showed drastic changes and disappearance of two broad absorption peaks. The physicochemical properties such as, surface charge, size, and shape of Te nanowires were found to be altered during exposure of cells, due to the instability and agglomeration of nanowires in the culture medium. These results suggest that the chemical components of the DMEM medium significantly affect the stability of Te nanowires. In addition, TEM images revealed that necrosis was the basic pattern of cell death, which might stem from the formation of toxic moieties of tellurium, released from nanowire structures, in the bioenvironment. These observations thus suggest that Te nanomaterials may pose potential risks to environmental and human health.