• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.86-92
• /
• 2016

A high-capacity battery installed in a hybrid vehicle or electric vehicle is used to power, or as a power supply for, electric sub-assemblies. In order to use a high-capacity battery as a power supply for electric sub-assemblies, such as an electronic control unit or for lighting, radio, and navigation, there is a need for a DC converter that changes a high voltage of 240-400V to a low voltage of 12-14V, which is done with a low-voltage DC-DC converter (LDC). An LDC undergoes long-term aging so as to reduce latent defects in the production process. With regard to the usual aging method, an LDC is a DC-DC converter. So, a DC power supply is connected and used as input, and a programmable DC electronic load is the output. For stable operation, a product having a larger capacity by 10% (compared to an LDC) is used, and has a structure where electric power is dissipated into 100% heat. So, there is a problem with volume, based on the use of two pieces of equipment to test the LDC, and another problem based on the generation of heat in the programmable DC electronic load. Hence, this paper suggests a load test method as a way of recycling, where a significant portion of the electricity dissipated as heat in a load tester is returned as input. The method realizes savings of 80% or more in the electricity dissipated as heat through improvement in the efficiency of the recycling load tester.

• Polymer(Korea)
• /
• v.34 no.4
• /
• pp.294-299
• /
• 2010

Clay-loaded polypropylene (PP) nanocomposites were fabricated via melt-compounding of two molecular weight ($M_w$) PPs (140 and 410 kg/mol) and octadecylammine-treated clay (C18MMT), with the assistance of maleic anhydride-grafted PP(PP-MAH), respectively, at $170^{\circ}C$ and $190^{\circ}C$. At both melt-compounding temperatures, the low-$M_w$ PP tends to easily diffuse into silicate layers, especially in the presence of the mobile PP-MAH, resulting in a marked increase in silicate layer spacing (above 58 $\AA$), when compared to 27 $\AA$ in the high-$M_w$ PP-based system. Due to relatively lower melt-viscosity of the low-$M_w$ PP-based system, however, there existed quasi-stacked clay aggregates with a thickness of 60~80 nm, while the high-$M_w$ PP-based nanocomposites showed relatively homogeneous dispersion of clays. The different morphologies are mainly related to changes in the viscoelastic properties of PPs, dependent on the processing temperature and their $M_{w}s$. The slight differences in nanocomposites induce discernible crystallization and mechanical behaviors. High-$M_w$ PP-based nanocomposites containing 1~3 wt% C18MMT showed improvement in both tensile strength and modulus, while maintaining the inherent ductility of pure PP.

• The Journal of the Korea Contents Association
• /
• v.22 no.7
• /
• pp.55-62
• /
• 2022

The perovskite solar cell is an active part of research in renewable energy fields such as solar energy, wind, hydroelectric power, marine energy, bioenergy, and hydrogen energy to replace fossil fuels such as oil, coal, and natural gas, which will gradually disappear as power demand increases due to the increase in use of the Internet of Things and Virtual environments due to the 4th industrial revolution. The perovskite solar cell is a solar cell device using an organic-inorganic hybrid material having a perovskite structure, and has advantages of replacing existing silicon solar cells with high efficiency, low cost solutions, and low temperature processes. In order to optimize the light absorption layer thin film predicted by the existing empirical method, reliability must be verified through device characteristics evaluation. However, since it costs a lot to evaluate the characteristics of the light-absorbing layer thin film device, the number of tests is limited. In order to solve this problem, the development and applicability of a clear and valid model using machine learning or artificial intelligence model as an auxiliary means for optimizing the light absorption layer thin film are considered infinite. In this study, to estimate the light absorption layer thin-film optimization of perovskite solar cells, the regression models of the support vector machine's linear kernel, R.B.F kernel, polynomial kernel, and sigmoid kernel were compared to verify the accuracy difference for each kernel function.

• Applied Chemistry for Engineering
• /
• v.33 no.6
• /
• pp.600-605
• /
• 2022

In this study, nitrogen oxide (NO_x) removal experiments were performed using a graphene based ceramic filter coated with a V₂O₅-WO₃-TiO₂ catalyst. Graphene oxide (GO) was prepared by Hummer's method using graphite, and the reduced graphene oxide was produced by reducing with hydrazine (N₂H₄). Vanadium (V), Tungsten (W), and Titanium (Ti) were coated by the sol-gel method, and then a metal oxide-supported filter was prepared through a calcination process at 350 ℃. A NO_x removal efficiency test was performed for the catalytic ceramic filters with UV light in a humid condition. When graphene oxide (GO) and reduced graphene oxide (rGO) were present on the filter, the NOx removal efficiency was superior to that of the conventional ceramic filter. Most likely, this is due to an improvement in the adsorption properties of NOx molecules on graphene coated surfaces. As the concentration of graphene increased, higher NO_x removal efficiency was confirmed.

• Membrane Journal
• /
• v.34 no.2
• /
• pp.87-95
• /
• 2024

Recent studies explore a wide array of desalination and water treatment methods, encompassing membrane processes such as reverse osmosis (RO), nanofiltration (NF), and electrodialysis (ED) to advanced capacitive deionization (CDI) and its membrane variant (MCDI). Comparative analyses reveal ED's cost-effectiveness in low-salinity scenarios, while hybrid systems (NF-MCDI, RO-NF-MCDI) show improved salt removal and energy efficiency. Novel ion separation methods (NF-CDI, NF-FCDI) offer enhanced efficacy and energy savings. These studies also highlight the efficiency of these methods in treating complex wastewater specific to various industries. Environmental impact assessments emphasize the need for sustainability in system selection. Additionally, the integration of microfabricated sensors into membranes allows real-time monitoring, advancing technology development. These studies underscore the variety and promise of emerging desalination and water treatment technologies. They provide valuable insights for enhancing efficiency, minimizing energy usage, tackling industry-specific issues, and innovating to surpass conventional method limitations. The future of sustainable water treatment appears bright, with continual advancements focused on improving efficiency, minimizing environmental impact, and ensuring adaptability across diverse applications.