• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.759-764
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• 2018

3D porous carbon electrodes (cNPIM), prepared by solution casting of a polymer of intrinsic microporosity (PIM-1) followed by nonsolvent-induced phase separation (NIPS) and carbonization are presented. In order to effectively control the pore size of 3D porous carbon structures, cNPIM was prepared by varying the THF ratio of mixed solvents. The SEM analysis revealed that cNPIMs have a unique 3D macroporous structure having a gradient pore structure, which is expected to grant a smooth and easy ion transfer capability as an electrode material. In addition, the cNPIMs presented a very large specific surface area ($2,101.1m^2/g$) with a narrow micropore size distribution (0.75 nm). Consequently, the cNPIM exhibits a high specific capacitance (304.8 F/g) and superior rate capability of 77% in an aqueous electrolyte. We believe that our approach can provide a variety of new 3D porous carbon materials for the application to an electrochemical energy storage.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

• Journal of Life Science
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• v.28 no.11
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• pp.1332-1338
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• 2018

Activated microglia, induced by various pathogens, protect neurons and maintain homeostasis of the central nervous system (CNS). However, severe activation causes neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease because of the secretion of various neurotoxic molecules, such as nitric oxide (NO), prostaglandin (PG), and pro-inflammatory cytokines. Because chronic microglial activation endangers neuronal survival, negative regulators of microglial activation have been identified as potential therapeutic candidates for treatment of many neurological diseases. One potential source of these regulators is Locusta migratoria, a grasshopper of the Acrididae, usually 4-6 cm in size, belonging to the family of large insects in Acrididae. This grasshopper is an edible insect resource that can be consumed by humans as protein source or used for animal feed. The aim of the present study was to examine the inhibitory effects of a L. migratoria ethanol extract (LME) on the production of inflammatory mediators in LPS-stimulated BV-2 microglia cells. The extract significantly inhibited the NO, iNOS, COX-2, and pro-inflammatory cytokine ($TNF-{\alpha}$, IL-6 and $IL-1{\beta}$) levels in BV-2 microglia cell. Because the inhibition of microglial activation may be an effective solution for treating brain disorders like Alzheimer's and Parkinson's diseases, these results suggest that LME may be a potential therapeutic agent for the treatment of brain disorders induced by neuroinflammation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.204-210
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• 2019

In case of a fire inside a tunnel, unlike ordinary roads, it is very difficult for a driver to obtain visibility, and a large accident is highly likely to occur. In this study, the smoke behavior, visible distance, and CO concentration of a jet fan were analyzed using the NIST fire simulation (FDS). All analyses were set to HRRPUA (Heat Release Rate Per Area) 3.6MW/m and all the analysis times were set to 600s. In all analyses by CFD, the results were confirmed at y=30m and y=110m, and smoke behavior analysis, visible range analysis, and carbon monoxide concentration were confirmed according to the diameter and flow rate. As the size and flow rate of the jet fan increased, the visibility distance was high at y=30m, and the concentration of carbon monoxide was also confirmed to be 0 ppm. Therefore, proper setting of the jet fan diameter and flow rate will be an excellent solution for fires in tunnels, and taking refuge at upstream area of a re-ventilated fan can reduce the number of casualties.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.87-103
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• 2019

Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.412-419
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• 2019

Negative space in the discipline of art defines the space around and between the subject of an image. The use of negative space is an element of artistic composition, since it is occasionally used to artistic effect as the "real" subject of an image. In painting, it is a technique that negatively touches the background of an object to be expressed, so that it gives a feeling of unique texture and silhouette by touching unnecessary parts while leaving necessary parts. As in art, negative space in a design can also be useful to identify an image of infeasible design ranges with a straightforward view. Similarity between two disciplines leads to the introduction of the negative space concept for design space exploration. A rough design space exploration using statistics and visual analytics may support more efficient decision-making, and can provide meaningful insights into the direction of early-phase system design. For this, the approach guarantees dynamic interactions between visualized information and human cognitive systems. Visual analytics is useful to summarize complex and large-scale data. It is useful for identifying feasible design spaces, as well as for avoiding infeasible spaces or highly risky spaces. This paper investigates the possible use of the negative space concept by using an application example.

• Smart Media Journal
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• v.8 no.1
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• pp.74-81
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• 2019

Recently, machine learning technology has had a significant impact on society, particularly in the medical, manufacturing, marketing, finance, broadcasting, and agricultural aspects of human lives. In this paper, we study how to apply machine learning techniques to foods, which have the greatest influence on the human survival. In the field of Smart Farm, which integrates the Internet of Things (IoT) technology into agriculture, we focus on optimizing the crop growth environment by monitoring the growth environment in real time. KT Smart Farm Solution 2.0 has adopted machine learning to optimize temperature and humidity in the greenhouse. Most existing smart farm businesses mainly focus on controlling the growth environment and improving productivity. On the other hand, in this study, we are studying how to apply machine learning with respect to harvest time so that we will be able to harvest fruits of the highest quality and ship them at an excellent cost. In order to apply machine learning techniques to the field of smart farms, it is important to acquire abundant voluminous data. Therefore, to apply accurate machine learning technology, it is necessary to continuously collect large data. Therefore, the color, value, internal temperature, and moisture of greenhouse-grown fruits are collected and secured in real time using color, weight, and temperature/humidity sensors. The proposed FPSML provides an architecture that can be used repeatedly for a similar fruit crop. It allows for a more accurate harvest time as massive data is accumulated continuously.

• Membrane Journal
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• v.31 no.5
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• pp.343-350
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• 2021

In this study the suction pressure was measured with respect to operational time by submersing the multi-bore capillary membrane module in membrane bioreactor(MBR). The hexagonal shape capillary module which has the nominal pore size of 0.2 ㎛, outer diameter of 6.4 or 4.2 mm was immersed in MLSS 8,000 mg/L active sludge aqueous solution, and confirmed changes with respect to permeation flux and air flow rate. It was operated by the filtration/relaxation(FR), FR with backwashing(FR/BW), and sinusoidal flux continuous operation(SFCO) modes. The suction pressure for the SFCO and FR modes was lower at 30 and 50 L/m²·hr, respectively. In addition, the suction pressure of the module with a small outer diameter was relatively low. The suction pressure of a large outer diameter was greatly increased, but it could be reduced by more than 40% by backwashing.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.33-44
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• 2019

Clinker layer is a stratum structure distributed in volcanic area such as Jeju Island. The clinker layers were formed in between the repetitive action of eruption and solidification of lava flows. Since the clinker layer contains a large amount of voids accompanied by the lava gas ejection process, there is a possibility of inducing overall stability of the ground due to the low stiffness and strength of the clinker layer. Therefore, in this study, site investigation was carried out at both ends of the 00 bridge where the clinker layers exist. And, based on the ground survey results, the behavior of shallow foundations was analyzed numerically. In addition, the improved shallow foundation behavior in grouting substitution using the chemical injection method of the clinker layer was compared with the shallow foundation behavior in the ground, and the grouting substitution efficiency of each layer was analyzed. As a result, the bearing capacity, the replacement efficiency and elastic settlement were different according to the presence or absence of the sediment layer. This is because the sediment layer has a lower stiffness and density than the clinker layer.