• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.53-61
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• 2021

This paper is a preliminary study for the development of a drone for inspection inside a boiler in a thermal power plant, which is a high-temperature environment, and validated whether the drone can fly normally through a high-temperature environment simulation using AirSim. In a high-temperature flight environment, the aerodynamic characteristics of the air density and viscosity are different from room temperature, and the flight performance of the drone is also changed accordingly. Therefore, in order to confirm the change of the aerodynamic characteristics of the propeller according to the temperature change, the propeller analysis and thrust test through JBLADE, and the operation characteristics prediction through the electric propulsion system performance prediction model were performed. In addition, the analysis and performance prediction results were applied to AirSim for simulation, and the aircraft redesigned through the analysis of the results. As a result of the redesign, it was confirmed that about 65% of the maximum power used before the redesign was reduced to 52% to obtain the necessary thrust when hovering in an environment of 80℃.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.3
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• pp.193-200
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• 2010

Anode off-gas of high temperature fuel cell still contains combustible components such as hydrogen, carbon monoxide and hydrocarbon. In this study, a catalytic combustor has been applied to the high temperature fuel cell so that the combustion of anode-off gas can be boosted up. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study is designed to perform the experimental investigation on the combustion characteristics of the three commercial catalysts with a different composition. Screening tests with three catalysts are preceded before the performance examination since it is necessary to determine the most suitable catalyst for design configuration of the catalytic combustor. The performance analysis shows that methane conversion rate strongly depends on gas hourly space velocity (GHSV) as well as inlet gas temperature. Additionally, the GSHV optimization results show that the optimum GHSV will be in the range between 18,000 $hr^{-1}$ and 36,000 $hr^{-1}$. It is also shown that the minimum inlet temperature of catalytic reaction of methane is from $100^{\circ}C$ to $150^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.93-96
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• 2008

This research performed strength improvement analysis after evaluating strength characteristics by estimated temperatures to evaluate the real time strength performance of 50 to 80 MPa high performance concrete equipped with heat resistance, and the results are as follows. The lesser W/B and the lesser target slump flow value difference, compression strength was shown to increase, and the more curing temperature becomes, the strength increased accordingly. According to the correlation review result of strength improvement analysis by estimated temperature change performed using logistic analysis model, the compression strength value predicted with logistic curve expression and the compression strength value measured in experiment were shown to have similar correlation, and the strength improvement analysis value by logistic model was shown to be estimated good when W/B is high.

• Computers and Concrete
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• v.2 no.3
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• pp.189-202
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• 2005

This paper presents an analysis of some experimental results concerning micro-structural tests, permeability measurements and strain-stress tests of four types of High-Performance Concrete, exposed to elevated temperatures (up to $700^{\circ}C$). These experimental results, obtained within the "HITECO" research programme are discussed and interpreted in the context of a recently developed mathematical model of hygro-thermal behaviour and degradation of concrete at high temperature, which is briefly presented in the Part 2 paper (Gawin, et al. 2005). Correlations between concrete permeability and porosity micro-structure, as well as between damage and cracks' volume, are found. An approximate decomposition of the thermally induced material damage into two parts, a chemical one related to cement dehydration process, and a thermal one due to micro-cracks' development caused by thermal strains at micro- and meso-scale, is performed. Constitutive relationships describing influence of temperature and material damage upon its intrinsic permeability at high temperature for 4 types of HPC are deduced. In the Part II of this paper (Gawin, et al. 2005) effect of two different damage-permeability coupling formulations on the results of computer simulations concerning hygro-thermo-mechanical performance of concrete wall during standard fire, is numerically analysed.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.641-648
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• 2011

KEPRI (KEPCO Research Institute) designed and operated the lab-scale high temperature electrolysis (HTE) system for hydrogen production with $10{\times}10cm^2$ 5-cell stack at $750^{\circ}C$. The electrolysis cell consists of Ni-YSZ steam/hydrogen electrode, YSZ electrolyte and LSCF based perovskite as air side electrode. The active area of one cell is 92.16 $cm^2$. The hydrogen production system was operated for 2664 hours and the performance of electrolysis stack was measured by means of current variation with from 6 A to 28 A. The maximum hydrogen production rate and current efficiency was 47.33 NL/hr and 80.90% at 28 A, respectively. As the applied current increased, hydrogen production rate, current efficiency and the degradation rate of stack were increased respectively. From the result of stack performance, optimum operation current of this system was 24 A, considering current efficiencies and cell degradations.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.442-449
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• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.3
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• pp.1-7
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• 2014

Heat pumps have received a fair amount of attention all over the world for their high efficiency and low environmental impact. Employing heat pumps for residential heating and cooling produces only about 2038 kg-$CO_2$/year, an amount which is less than half that of conventional boiler systems. However, the use of single-stage heat pumps becomes uneconomical when they are operated at very low evaporating temperature or high condensing temperature. Two-stage heat pumps systems can be used successfully for low or high temperature applications. In this paper, the experimental study on the performance of two-stage heat pump with an economizer was executed in heating mode. When the secondary fluid inlet temperature to the indoor heat exchanger increased, the COP enhancement rate of two-stage heat pump with an economizer was increased. For all outdoor inlet temperature conditions, the performance of the heat pump with an economizer was higher than it without an economizer.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.4
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• pp.1-8
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• 2001

In this paper we propose high performance system with reduced hardware architecture to convert a color tone. Conversion for the color tone of a input image is necessary to calculate the color temperature of the image Conventional way of calculating the temperature uses algorithm using the method calculating 2-D chromaticity coordinates. But it requires bulky hardware[1]. This paper propose the color temperature calculation method about 1-D chromaticity coordinates that reduces the hardware complexity while keeping the performance of the 2-D color temperature algorithm . The proposed method is verified by fLCD-TV system using the Xilinx Virtex FPGA XCV 2000E-6BG560 that has 1344*806 resolution and requires a high-speed 65MHz operation.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.3
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• pp.149-155
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• 2021

Most of the reformer experiments have been conducted only in high-temperature operation conditions above 700℃. However, to design high efficiency solid oxide fuel cell, it is necessary to test actual reaction performance in mid-temperature (550℃) operation areas. In order to study the operation characteristics and performance of commercial reforming catalysts, a reforming performance experiment was conducted on mid-temperature. The catalysts used in this study are Ni-based FCR-4 and Ru-based RuA, RuAL. Experiments were conducted with a Steam-to-carbon ratio of 2.0 to 3.0 under gas hourly space velocity (GHSV) 2,000 to 5,000 hr-1. As a result, RuA and RuAL catalysts showed similar gas composition to the equilibrium regardless of the reforming temperature. However, the FCR-4 catalyst showed a lower hydrogen yield compared to the equilibrium under high GHSV conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.945-948
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• 2017

A valve used in a high temperature and pressure condition for high-speed vehicle application was developed for fuel supply and cooling system. For weight reduction purpose, the size outline of valve was optimized based on its performance and operating environment. And the rigidity design was adopted by minimizing uses of sealing parts to prevent leakages. Also, A fluid analysis was performed to derive the optimized internal flow path design in consideration of minimized pressure drop. Finally, the valve performance was verified by installing the valve into the test equipment which enable to simulate endothermic fuel of high temperature in high-speed vehicle.