• KEPCO Journal on Electric Power and Energy
• /
• v.8 no.2
• /
• pp.151-157
• /
• 2022

The transition to renewable energy, especially the expansion of photovoltaic (PV) generation, has become a global megatrend that can no longer be reserved. However, since the site for PV is limited, it is necessary to use the land efficiently. As an alternative, the concept of utility scale agricultural PV(UAPV) is a technology that continues farming in the lower part and installs PV in the upper part of farmland to efficiently use the land. Therefore, for UAPV, the growth of crops in the lower part and the optimal operation of PV in the upper part are important. In this, we analyze the characteristics of the upper PV generation system in the UAPV based on the empirical results under various conditions, and propose future research directions of the UAPV.

• Advances in nano research
• /
• v.16 no.6
• /
• pp.549-564
• /
• 2024

This paper aims to analyze the dynamic response of thermoelectric carbon nanotube-reinforced composite (CNTRC) beams under moving harmonic load resting on Pasternak elastic foundation. The governing equations of thermoelectric CNTRC beam are obtained based on the Karama shear deformation beam theory. The beams are resting on the Pasternak foundation. Previous articles have not performed the moving load mode with the analytical method. The exact solution for the transverse and axial dynamic response is presented using the Laplace transform. A comparison of previous studies has been published, where a good agreement is observed. Finally, some examples were used to analyze, such as excitation frequency, voltage, temperature, spring constant factors, the volume fraction of Carbon nanotubes (CNTs), the velocity of a moving harmonic load, and their influence on axial and transverse dynamic and maximum deflections. The advantages of the proposed method compared to other numerical methods are zero reduction of the error percentage that exists in numerical methods.

• Journal of the Korean institute of surface engineering
• /
• v.57 no.3
• /
• pp.214-220
• /
• 2024

In this study, three-dimensional (3D) networks structure using single-walled carbon nanotubes (SWCNTs) for Si-graphite composite electrode was developed and studied about effects on the electrochemical performances. To investigate the effect of SWCNTs on forming a conductive 3D network structure electrode, zero-dimensional (0D) carbon black and different SWCNTs composition electrode were compared. It was found that SWCNTs formed a conductive network between nano-Si and graphite particles over the entire area without aggregation. The formation of 3D network structure enabled to effective access for lithium ions leading to improve the c-rate performance, and provided cycle stability by alleviating the Si volume expansion from flexibility and buffer space. The results of this study are expected to be applicable to the electrode design for high-capacity lithium-ion batteries.

• Journal of the Korean Electrochemical Society
• /
• v.12 no.3
• /
• pp.263-270
• /
• 2009

Carbon felt surface was modified by heat or acid treatment in order to use for the electrode of a redox-flow battery. Polymers on the surface of carbon felt was removed and oxygen-containing functional group was attached after the thermal treatment of carbon felt. Thermal treatment was better for the stability of the carbon structure than the acid treatment. Oxygen-containing functional group on the thermally treated carbon felt at 500$^{\circ}C$ was confirmed by XPS and elementary analysis. BET surface area was increased from nearly zero to 96 $m^2/g$. Thermally treated carbon felt at 500$^{\circ}C$ showed lower activation polarization than the thermally treated carbon felt at 400$^{\circ}C$ and the acid-treated carbon felt in the cyclicvoltammetry and polarization experiments. The thermally treated carbon felts at 400$^{\circ}C$ and 500$^{\circ}C$ and the acid-treated carbon felt was applied for the electrode to prepare vanadium redox flow battery. Voltage efficiencies of charge/discharge were 86.6%, 89.6%, and 96.9% for the thermally treated carbon felts at 400$^{\circ}C$ and 500$^{\circ}C$ and the acid-treated carbon felt, respectively.

• Journal of Information Display
• /
• v.2 no.3
• /
• pp.60-65
• /
• 2001

Lateral type poly-silicon field emitters were fabricated by utilizing the LOCOS (Local Oxidation of Silicon) process. For the implementation 'of an ideal field emission device with quasi-zero tunneling barrier, a new and fundamental approach has used conducted by introducing an intelligent carbon-based thin layer on the cathode tip surface via a field-assisted self-aligning of carbon (FASAC) process. Fundamental lowering of the turn-on field for the electron emission was feasible through the control of both the tip shape and surface barrier height.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.310-313
• /
• 2005

The conical fluidizing system of a binary mixture of Geldart C powders and Geldart A particles was defined as the conical powder-particle fluidized bed. We used a cold conical powder-particle fluidized bed model having a 0.104m-I.D. and 0.6m-high with an apex angle of $10^{\circ}$ for fluidization of a binary powder-particle mixture of 50 $vol\%$ fine carbon black powders (HI-900L, Korea Carbon Black Co.) and coarse alumina particles $(90{\mu}m)$ under different superficial gas velocities (0-0.1 m/s). The differential bed pressure drop increases with increasing gas velocity, and it goes from zero to a maximum value with increasing or decreasing gas velocity. In the conical fluidized beds of fine powders, demarcation velocities of the partial fluidization, full fluidization, partial defluidization was not observed.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.150.1-150.1
• /
• 2011

The global rise of greenhouse gas(GHG) emissions and its potentially devastating consequences require a comprehensive regulatory framework for reducing emissions, including those from the transport sector. alternative fuels and technologies have been promoted as a means for reducing the carbon intensity of the transport sector. Renewable fuel policies were historically motivated by energy security concerns, and to promoted agricultural industries. In the last decade, biofuels have also been discussed as low or net-zero carbon soures of energy for transportation. Hence, the development of biofuels has been supported by a range of policy instruments, including volumetric targets or blending mandates, tax incentives or penalties, preferential government purchasing, government funded research, development in world-wide. As one of the most powerfuel instruments, renewable fuel mandates require fuel producers to produce a pre-defined amount(or share) of biofuels and blend them with petroleum fuel. In this study, we reviewed Renewable Fuel Standard(RFS, USA), Renewable Transport Fules Obligation (RTFO, UK) as a renewable fuel mandate policy to reduce GHG. This includes not only mandate system for blending of biofuels in transport fuels, but also sustainability to use biofuels in this system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.35 no.3
• /
• pp.269-274
• /
• 2022

We prepared carbon nanotube (CNT) paper by a vacuum filtration method for the use of a chip-typed resistor as a precision passive device with a constant resistance. Hybrid resistor composed of the CNT resistor with a negative temperature coefficient of resistance (T.C.R) and a metal alloy resistor with a positive T.C.R could lead to a constant resistance, because the resistance increase owing to the temperature increase at the metal alloy and decrease at the CNT could counterbalance each other. The constant resistance for the precision passive devices should be maintained even when a heat was generated by a current flow resulting in resistance change. Performance reliabilities of the CNT resistor for the precision passive device applications such as electrical load limit, environmental load limit, and life limit specified in IEC 60115-1 must be ensured. In this study, therefore, the rated power determination and T.C.R tests of the CNT paper were conducted. -900~-700 ppm/℃ of TCR, 0.1~0.2 A of the carrying current capacity, and 0.0625~0.125 W of the rated power limit were obtained from the CNT paper. Consequently, we confirmed that the application of CNT materials for the precision hybrid passive devices with a metal alloy could result in a better performance reliability with a zero tolerance.

• ALGAE
• /
• v.29 no.1
• /
• pp.35-45
• /
• 2014

Palmaria palmata was integrated with Atlantic halibut Hippoglossus hippoglossus on a commercial farm for one year starting in November, with a temperature range of 0.4 to $19.1^{\circ}C$. The seaweed was grown in nine plastic mesh cages (each $1.25m^3$ volume) suspended in a concrete sump tank ($46m^3$) in each of three recirculating systems. Two tanks received effluent water from tanks stocked with halibut, and the third received ambient seawater serving as a control. Thalli were tumbled by continuous aeration, and held under a constant photoperiod of 16 : 8 (L : D). Palmaria stocking density was $2.95kg\;m^{-3}$ initially, increasing to $9.85kg\;m^{-3}$ after a year. Specific growth rate was highest from April to June (8.0 to $9.0^{\circ}C$), 1.1% $d^{-1}$ in the halibut effluent and 0.8% $d^{-1}$ in the control, but declined to zero or less than zero above $14^{\circ}C$. Total tissue nitrogen of Palmaria in effluent water was 4.2 to 4.4% DW from January to October, whereas tissue N in the control system declined to 3.0-3.6% DW from April to October. Tissue carbon was independent of seawater source at 39.9% DW. Estimated tank space required by Palmaria for 50% removal of the nitrogen excreted by 100 t of halibut during winter is about 29,000 to $38,000m^2$, ten times the area required for halibut culture. Fifty percent removal of carbon from the same system requires 7,200 to $9,800m^2$ cultivation area. Integration of P. palmata with Atlantic halibut is feasible below $10^{\circ}C$, but is impractical during summer months due to disintegration of thalli associated with reproductive maturation.

• Journal of the Korean Institute of Educational Facilities
• /
• v.25 no.4
• /
• pp.11-18
• /
• 2018

Global warming is happening now and inevitable. Everyone knows that immediate action should be taken to slow it down, but uncertain about the effective solution. Despite global efforts to reduce greenhouse gas emissions, sea levels are rising gradually. In 2013, Cornell University announced the Climate Action Plan(CAP) to make the campus greener, to reduce waste, and to ensure efficient use of resources. In particular, they set a goal of reducing energy use by 2050 and making carbon emissions to zero. Accordingly, the purpose of this study is to analyse the case of the master plan of Cornell Tech campus and its major buildings. Mainly, The House, faculty and student housing of Cornell Tech and the world tallest certified passive house, will be the main precedent that shows the architectural planning of passive house. Passive house technology, which was thought to be possible only in single-family houses, can be applied to high-rise buildings. If any passive house technology of The House project is actively introduced into the dormitory projects of domestic universities that are about to be built or renovated, it will be a good opportunity for the university to take the lead in preparing for global warming.