• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.99.2-99.2
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• 2011

Transparent conducting oxides (TCOs) supported on glass are widely used as substrates in PEC studies for photovoltaic hydrogen generation applications However, high sheet resistane ($10{\sim}15{\Omega}/cm^2$) and fragileness of glass-supported TCO substrates are the obstacles to produce the large area PEC cells. Such internal sheet resistance is detrimental to efficient collection of photogenerated majority charge carriers at the photoactive material and electrolyte interface. Moreover, these TCO substrates are very expensive and consume about 40~60% cost of the devices. Hence, a low sheet resistance of the substrate is a key point in improving the performance of PEC devices. Metallic substrates coated with a photoactive material would be a good choice for efficient charge collection. Such metal substrates based photanodes are best candidate for large-scale phtoelectrochemical water splitting for hydrogen generation. In this study, we report the enhanced PEC performance of $WO_3$ film on metal(chemical etched, bare) substrate. It is proposed that interface between $WO_3$ and the metal substrate is responsible for efficient charge transfer and demonstrated significant improvement in the photoelectrochmical performance. X-ray diffration and FESEM suduies reveled that $WO_3$ films are monoclinic, porous, polycrystalline with average grain size of ~50nm. Photocurrent of $WO_3$ prepared on metal substrates was measured in 0.5M $H_2SO_4$ electroyte under simulated $100mW/cm^2$ illumination.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.81-87
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• 2017

SOFC(Solid Oxide Fuel Cell) is one of the high-temperature fuel cells, SOFC system and Stack has a high temperature operating Characteristics. These Characteristics cause a lot of trouble in the design of the system and selection materials, securing durability, and securing safety performance. Therefore, For Commercialization and Supply of SOFC, the development of safety performance assessment techniques and evaluation systems should go together. In this study, we analyzed the evaluation items of SOFC Safety performance standards and risk factors of the stack for design of stack safety performance evaluation system. Based on the analyzed data, the evaluation item was deducted for design of stack safety performance evaluation system. Through the results of this study, we expect to facilitate the supply of SOFC and contribute to a safe use environment.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1187-1198
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• 2021

Sea wind isrecently drawing attraction as one of the sources of renewable energy. Thisstudy describes a new method to produce a 10 m resolution sea wind field using Sentinel-1 images and low-resolution NWP (Numerical Weather Prediction) data with artificial intelligence technique. The experiment for the South East coast in Korea, 2015-2020,showed a 40% decreased MAE (Mean Absolute Error) than the generic CMOD (C-band Model) function, and the CC (correlation coefficient) of our method was 0.901 and 0.826, respectively, for the U and V wind components. We created 10m resolution sea wind maps for the study area, which showed a typical trend of wind distribution and a spatially detailed wind pattern as well. The proposed method can be applied to surveying for wind power and information service for coastal disaster prevention and leisure activities.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.54-63
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• 2015

Increasing air pollution levels and the global oil crisis has become a major hindrance in the growth of our automobile sector. Traditional Internal Combustion engines running on non-renewable fuels are proving to be the major culprit for the harmful effects on environment. With few modifications and also with assistance of few additional components current small SI engines can be modified into a pneumatic engine (commonly known as Compressed Air Engines) without much technical complications where the working fluid is compressed air. The working principle is very basic as adiabatic expansion of the compressed air takes place inside the cylinder pushing the piston downwards creating enough MEP to run the crank shaft at decent RPM. With the assistance of new research and development on pneumatic engines can explore the potential of pneumatic engines as a viable option over IC engines. The paper deals with analysis on RPM variation with corresponding compressed air injection at different crank angles from TDC keeping constant injection time period. Similarly RPM variation can also be observed at different injection pressures with similar injection angle variation. A setup employing a combination of magnetic switch (reed switch), magnets and solenoid valve is used in order to injection timing control. A conclusive data is obtained after detailed analysis of RPM variation that can be employed in newly modified pneumatic engines in order to enhance the running performance. With a number of benefits offered by pneumatic engine over IC engines such as no emissions, better efficiency, low running cost, light weight accompanied by optimized injection conditions can cause a significant development in pneumatic engines without any major alteration.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.84.2-84.2
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• 2010

PEMS (printed electro-mechanical system) is fabricated by means of various printing technologies. Passive and active components in 2D or 3D such as conducting lines, resistors, capacitors, inductors and TFT, which are printed with functional materials, can be classified in this category. And the issue of PEMS is applied to a R2R process in the manufacturing process. In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem: it is difficult to apply toa continuous process as a R2R printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, anelectrostatic atomizer sprays micro-drops from the solution injected into the capillary, with electrostatic force generated by electric potential of about tens of kV. ESD method is usable in the thin film coating process of organic materials and continuous process as a R2R manufacturing process. Therefore, we experiment the thin films forming of PEDOT:PSS layer and Active layer which consist of the P3HT:PCBM. The result of experiment, organic solar cell using ESD thin film coated method is occurred efficiency of about 1.4%. Also, the case of only used to ESD method in the active layer coating is occurred efficiency of about 1.86% as the applying a spin coating in the PEDOT:PSS layer. We can expect that ESD method is possible for continuous process to manufacture in the organic solar cell or OLED device.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.77.1-77.1
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• 2010

Durability problems of gas diffusion layer(GDL) is one of the important issues for accomplishing commercialization of proton exchange membrane fuel cell(PEMFC). GDL is strongly related to the performance of PEMFC because one of the main function of GDL is to work as a path of fuel, air and water. When the GDL is degraded, it causes water balance problems such as the flooding phenomenon. Thus, investigating the durability characteristics of the GDL is important and understanding the GDL degradation process is needed. In this study, the GDLs are degraded by carbon corrosion stress method which is the electrochemical degradation mode. To determine the effects of carbon corrosion of the GDL, 1.45 V of potential is imposed for 96 hours. In this manner, in the previous research, the structure between the substrate and the MPL is weaken. Further investigations are needed to clarify this phenomenon. Therefore, in this study, the carbon corrosion stress method is carried out with GDLs which have various MPL penetration levels and the effects of the MPL penetration level on the characteristics change of the GDL are analyzed. The changes in characteristics are measured with various properties of GDL such as weight, thickness and static contact angle. The degraded GDL shows loss of their properties.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.47.2-47.2
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• 2010

For reducing outer reflection in mono-crystalline silicon solar cell, wet texturing process has been adapted for long period of time. Nowadays mixed solution with potassium hydroxide and isopropyl alcohol is used in silicon surface texturing by most manufacturers. In the process of silicon texturing, etch rate is very critical for effective texturing. Several parameters influence the result of texturing. Most of all, temperature, process time and concentration of potassium hydroxide can be classified as important factors. In this paper, temperature, process time and concentration of potassium hydroxide were set as major parameters and 3-level test matrix was created by using robust design for the optimized condition. The process optimization in terms of lowest reflection and stable etch rate can be traced by using robust design method.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.288-294
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• 2009

Various polymer electrolyte membrane fuel cell (PEMFC) startup procedures were tested to explore possible techniques for reducing performance decay and improving durability during repeated startup-shutdown cycles. The effects of applying a dummy load, which prevents cell reversal by consuming the air at the cathode, on the degradation of a membrane electrode assembly (MEA) were investigated via single cell experiments. The electrochemical results showed that application of a dummy load during the startup procedure significantly reduced the performance decay, the decrease in the electrochemically active surface area (EAS), and the increase in the charge transfer resistance ($R_{ct}$), which resulted in a dramatic improvement in durability. After 1200 startup-shutdown cycles, post-mortem analyses were carried out to investigate the degradation mechanisms via various physicochemical methods including FESEM, an on-line $CO_2$ analysis, EPMA, XRD, FETEM, SAED, FTIR. After 1200 startup-shutdown cycles, severe Pt particle sintering/agglomeration/dissolution and carbon corrosion were observed at the cathode catalyst layer when starting up a PEMFC without a dummy load, which significantly contributed to a loss of Pt surface area, and thus to cell performance degradation. However, applying a dummy load during the startup procedure remarkably mitigated such severe degradations, and should be used to increase the durability of MEAs in PEMFCs. Our results suggest that starting up PEMFCs while applying a dummy load is an effective method for mitigating performance degradation caused by reverse current under a repetition of unprotected startup cycles.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.126.2-126.2
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• 2011

ZnS thin films were deposited with the radio frequency magnetron sputtering technique at various temperatures and sputtering powers. With the increase in the deposition temperature and the decrease in the radio frequency sputtering power, the crystallinity was increased and the surface roughness was decreased, which lead to the decrease in the electrical resistivity of the film. It is also clearly observed that, the intensity of the (111) XRD peak increases with increasing the substrate temperature. On the other hand, as seen in the FWHM decreased with increasing the substrate temperature. Since the FWHM of the (111) diffraction peak is inversely properties to the grain size of the film, then grain size of ZnS thin film increases with increasing the substrate temperature. The electrical resistivity and optical transmittance of the ZnS film as a function of the post-annealing temperature. It can be seen that with the annealing temperature set at $400^{\circ}C$, the resistivity decreases to a minimum value of $2.1{\times}10^{-3}\;{\Omega}cm$ and the transmittance increases to a maximum value of 80% of the ZnS film.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.145-151
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• 2013

This research is to suggest a method for investigating car number plates among the information managed in parking facilities. The investigation of car number plate is generally used to know how long vehicles are parked. Also, it can provide the information about the parking turnover rate and the mean parking duration of parked vehicles. This research performs the investigation using cameras at a distance of time. That is, the given distance of time from cameras is assigned to each parked vehicle, and then it can find the mean parking time of parked vehicles. Also, it can check the parking turnover rate of parked vehicles at a space unit of parking lot in an hour. The information such as the mean parked duration and the parking turnover rate of parked vehicles taken from this method is helpful to find and understand the inefficient use of parking facilities. With this suggested method, this research attempted to check the mean parking duration and the parking turnover rate of parked vehicles.