• Journal of Electrochemical Science and Technology
• /
• v.12 no.3
• /
• pp.346-357
• /
• 2021

In recent years, supercapacitors have been developed rapidly as a rechargeable energy storage device. And the performance of supercapacitors is depending on electrode materials, the preparation method and performance of electrode materials have become the primary goal of scientific development. This study synthesizes Co₃O₄@MnO₂@PPy cathode material with porous pattern core-shell structure by hydrothermal method and electrodeposition. The result samples are characterized by X-ray diffraction transmission/scanning electron microscope, and X-ray photoelectron spectroscopy. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by PPy depositing. The specific capacitance of Co₃O₄@MnO₂@PPy is 977 F g^-1 at 1 A g^-1, the capacitance retention rate of 105%. Furthermore, the electrochemical performance of Co₃O₄@MnO₂@PPy//AC asymmetric supercapacitor assembles with AC as the negative electrode material is significantly better than that of MnO₂//AC and Co₃O₄@MnO₂//AC. The capacity of Co₃O₄@MnO₂@PPy//AC is 102.78 F g^-1. The capacity retention rate is still 120% for 5000 charge-discharge cycles.

• Proceedings of the KIEE Conference
• /
• 1987.07a
• /
• pp.674-677
• /
• 1987

• Journal of Food Hygiene and Safety
• /
• v.18 no.2
• /
• pp.87-93
• /
• 2003

This study was performed to investigate aflatoxin reduction resulting from the pre-treatment and the cooking and processing of corn. Aflatoxin was produced by Aspergillus parasiticus ATCC 15517 on a type of corn imported from the United States. The aflatoxin-produced com (AC) was pre-treated in three ways in order to reduce aflatoxin: exposure to sun light for 7 days (SC); ultraviolet irradiation for 56 hours (UC); and washing with water three times (WC). Four kinds of cooking and processing methods (boiling, steaming, baking, and popping) were used to reduce aflatoxin in the AC control, SC, UC, and WC. These treatments produced com gruel, com cakes, com bread and popcorn. The aflatoxin content in the samples was determined by high performance liquid chromatography. The total aflatoxin level of the AC was significantly decreased by sun light and UV (p<0.05), and decreased by washing. After cooking and processing the AC, SC, UC, and WC, and averaging the total aflatoxin levels in the final products, the greatest reduction was found in the com gruel, then the popcorn, then the corn cakes, and the least reduction in the com bread. These results indicate that sunlight and ultraviolet energy could be effective factors in aflatokin degradation in corn before cooking and processing. This study also indicates that boiling, steaming, baking and popping were helpful in reducing the aflatoxin level in the com and that the most helpful factors were exposure time to heat. More research is needed to reduce the aflatoxin level down to below the maximum tolerable level of aflatoxin in foods.

• Journal of Energy Engineering
• /
• v.25 no.1
• /
• pp.92-99
• /
• 2016

In this paper, After the Paris climate conference (COP21) in December 2015, 195 countries adopted the first-ever universal, legally binding global climate deal. As sustained increase of renewable energy and digital load, to implemented and operated Microgrid system's power distribution by DC power distribution. This reduce the loss of power conversion step occurring based on the AC power distribution system and eliminate the loss caused by the reactive power in power distribution system. For this reason, DC Microgrid will be extended to support evidence of National energy policies, Microgrid project status, DC distribution status, and to suggest process of DC power distribution in Microgrid construction project.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.11
• /
• pp.1994-2000
• /
• 2008

The output power of photovoltaic(PV) generation system is strongly affected by weather conditions. To make up for the defect of solar energy, energy storages such as battery and electrolyzer are usually integrated with photovoltaic cell. This paper focuses on the way to store energy surplus with battery and electrolyzer and to provide energy with battery. Photovoltaic generation system is modeled with PV cell, DC/DC converter, DC/AC inverter, battery and electrolyzer. The operation algorithm to regulate PV output power with battery and electrolyzer is suggested. The simulation results show that battery and electrolyzer effectively cooperate with each other to compensate the fluctuation of PV generation system.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.2B no.3
• /
• pp.100-108
• /
• 2002

A simple sustain driver employing an energy recovery function is proposed as a highly efficient driver of a plasma display panel. The proposed driver uses dual resonance in the sustaining mode operation: a main resonance between an inductor and an external capacitor to produce alternative pulses and a sub-resonance between an inductor and a panel to recover the energy consumption by the capacitive displacement current of the PDP. The operational principle and design procedure of the proposed circuit are presented with theoretical analysis. The operation of the proposed sustain driver is verified through simulation and experiments based on a 7.5-inch-diagonal panel with a 200 KHz operating frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.971-974
• /
• 2014

Reflect the social concerns of recent energy saving in this paper. The LED market is continuing to grow continuously. But it is now high light energy conversion led lights., We propose converting the light energy-saving method for these LED lights. Generated the cumulative loss of the conversion done at each light change from the current power of the LED lights. The cumulative loss to achieve minimal energy loss resulting from the improved performance.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.3
• /
• pp.491-498
• /
• 2020

Recently, In the production line of batteries, charge and discharge tests are essential to verify battery characteristics. In this case, the battery charging uses a unidirectional AC/DC converter capable of output voltage and current control, and the discharge uses a resistive load. Since this method consumes energy during discharge, it must be replaced with a bi-directional AC/DC converter system capable of charging and discharging. Although it is difficult to replace the connected inverter part of the bi-directional AC/DC converter system due to the high cost, the spread of the solar-connected inverter rapidly increases as the current solar supply business is activated, and thereby the solar-connected type Inverter prices are plunging. If it can be used as a power converter for battery discharge without program modification of the solar-powered inverter, it will have competition. In this paper, propose a new battery discharge system using a combination of a photovoltaic DC/DC simulator and photovoltaic PCS using a battery to be used as a power converter for battery discharge without program modification of a low-cost photovoltaic inverter. In addition, propose an optimal solar characteristic curve for the stable operation of PCS. The validity of the proposed system was verified using a 500[W] class solar DC/DC simulator and a solar PCS prototype.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.1
• /
• pp.111-116
• /
• 2018

The environmental impacts of a 1 kW polymer electrolyte membrane fuel cell (PEMFC) system are quantitatively assessed by performing a Life Cycle Assessment (LCA) study. A PEMFC system produces electricity and heat simultaneously, so an appropriate allocation of associated inputs and outputs is performed between the electricity and heat produced. The environmental impacts of the PEMFC system on the impact categories such as global warming (GW), abiotic depletion (AD), acidification (AC), and eutrophication (EU) are assessed from the life cycle impact assessment. The impact indicator results of the impact assessment on these impact categories are obtained as $3.70E-01kg\;CO_2\;eq./kWh$, 1.86E-03 kg Sb eq./kWh, $4.09E-04kg\;SO_2\;eq./kWh$, and $1.88E-05kg\;PO_4{^{3-}}/kWh$, respectively. For all impact categories studied the most influential stage is the operation stage, which accounts for 98.8%, 98.7%, 70.3%, and 62.3% of the total impact on GW, AD, AC, and EU, respectively. For the impact categories of AD, AC, and EU, most of the environmental impacts during the operation stage is attributed to the production of city gas. However, for the impact category of GW, $CO_2$ emission from the reforming process of city gas is the main reason for the largest contribution of the operation stage to the total impact results.

• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1280-1287
• /
• 2019

Grid-connected bidirectional PCS(Power Conditioning System) technology is a technology for implementing distributed renewable energy smart grid. And it is always charged by using power collected from solar modules and commercial grid power among vast smart grid systems, and stored when needed.It is a hybrid energy storage device that allows power to be released into the low voltage system. To this end, a PV input power converter with MPPT function, a bidirectional power converter for battery charging and discharging, and a DC Link input are output to a 3 phase 380V AC system, and if nessary, the bidirectional DC/DC converter We designed and developed a PCS with three power converter structures composed of inverters that perform battery charging. Currently, this system is applied to the site of Jeju, which is vulnerable to power outages and fire accidents.