• Transactions of the Korean hydrogen and new energy society
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• v.14 no.4
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• pp.335-347
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• 2003

High temperature electrolysis (HTE) can become a key target technology for fulfilling the hydrogen requirement for the future hydrogen economy. This technology is based upon the partial replacement of electricity with heat energy for the electrolysis. Although the current research status of high temperature electrolysis in many countries remains at the small laboratory scale, the technology has great potential for producing hydrogen at a higher efficiency than low-temperature electrolysis (LTE). The efficiency of LTE is not expected to rise above 40%, whereas the efficiency of HTE has been reported to be above 50%. The higher efficiency of HTE would reduce costs by more than 30% compared to LTE. In this study, the technical data regarding the HTE of water and the resulting hydrogen production are reviewed, with an emphasis on the application of high temperature solid electrolyte and oxide electrodes for the HTE process.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.546-552
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• 2020

In this study, optimization research was conducted through statistical analysis with the aim of maximizing the efficiency of organic matter reduction and hydrogen production by applying electrolysis process at sewage treatment plant. Statistical analysis and optimal operating conditions of organic matter removal efficiency and H2 generation, which varied with various conditions in the electrolysis process, were derived using response surface methodology. As a result, 1,268 μS/cm of conductivity, 350 A current, and pH 3.2 was found to be the optimum condition to reach the desired value as 38% of organic matter reduction and 2.58 L/min of H2 production. The experiment also determined that the optimization study was reliable. Base on this study, it was confirmed that the removal of organic matter and hydrogen production could be stably by applying the electrolysis process in the sewage treatment plant.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.14-26
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• 2024

Global efforts continue with the goal of transition to a "carbon neutral (net zero)" society with zero carbon emissions by 2050. For this purpose, the technology of water electrolysis is being developed, which can store electricity generated from renewable energies in large quantities and over a long period of time as hydrogen. Recently, various research and large-scale projects on 'green hydrogen', which has no carbon emissions, are being conducted. In this paper, a comparison of water electrolysis technologies was carried out and, based on data provided by the International Energy Agency (IEA), large-scale water electrolysis demonstration projects were analyzed by classifying them by technology, power supply, country and end user. It is expected that through the analysis of large-scale water electrolysis demonstration projects, research directions and road maps can be provided for the development/implementation of commercial projects in the future.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.238-243
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• 2007

The composite powder of Cu and YSZ was synthesized for a high temperature electrolysis cathode by mechanical milling. The average Cu particle size was reduced to 5 micro-meter from 48 micro-meter after the mechanical ball milling. The composite powder showed that Cu particles were uniformly covered with finer YSZ particles. Sub-micron sized pores were uniformly dispersed in the Cu/YSZ composit. Homogeneously-dispersed fine YSZ in the composite is expected to the increase in triple phase boundaries, thereby leading the enhanced performance of cathode.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.65-73
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• 2020

To reduce the hydrogen production cost through the utilizing the oxygen and improving the capacity factor of water electrolysis used to energy storage of renewable energy, the hybrid hydrogen production process which has dual operating concept of using the water electrolysis as energy storage and oxygen production process for biomass gasification was proposed. Moreover, Techno-economic analysis on this system was quantitatively performed.

• Korean Journal of Materials Research
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• v.14 no.10
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• pp.743-748
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• 2004

Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by the direct ball milling of Ni and YSZ powder. The ball milling was carried out in dry process and in ethanol with varying milling time. While the dry-milling decreased the average size from 65 to $80{\mu}m$, the wet-milling decreased the average size down to $10{\mu}m$. In addition, very fine particles less than $0.1{\mu}m$ were observed in the wet-milling condition. The subsequent process of cold-pressing and sintering at $900^{\circ}C$ for 2 h did not affect the particle size of dry-milled powder. The electrical conductivity of the dry-milled Ni/YSZ cermet showed the value of $5{\times}10^{2}\;S/cm$ and this value was increased to $1.4{\times}10^{4}\;S/cm$ after the sintering at $900^{\circ}C$ for 2 h.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.2
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• pp.226-234
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• 2018

Even though the nuclear power plants has many advantages, safety issues of nuclear power plants are crucial factors of reliable operation. A tritium detector is a useful sensor to analyze amount of exposed radiation from the nuclear power plants. Currently, concentration of underwater tritium is measured precisely but it takes very long time. Since electrolysis is extracted hydrogen from the coolant of nuclear power plant, it can motivate to develop new type of real-time sensor. In this study, Proton Exchange Membrane (PEM) electrolyzer is studied for candidate as preprocessor of real-time tritium detector. Characteristics of the unit PEM electrolyzer were experimentally investigated. A simulation model is developed to understand physical behavior of unit PEM electrolyzer under dynamic operation.

• Korean Journal of Materials Research
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• v.18 no.7
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• pp.384-388
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• 2008

Hydrogen production via high high-temperature steam electrolysis consumes less electrical energy than compared to conventional low low-temperature water electrolysis, mainly due to the improved thermodynamics and kinetics at elevated temperaturetemperatures. The elementalElemental powders of Cu, Ni, and YSZ are were used to synthesize high high-temperature electrolysis cathodecathodes, of Ni/YSZ and Cu/YSZ composites, by mechanical alloying. The metallic particles of the composites were uniformly covered with finer YSZ particles. Sub-micron sized pores are were homogeneously dispersed in the Ni/YSZ and Cu/YSZ composites. In this study, The cathode materials were synthesized and their Characterizations properties were evaluated in this study: It was found that the better electric conductivity of the Cu/YSZ composite was measured improved compared tothan that of the Ni/YSZ composite. Slight A slight increase in the resistance can be produced for in a Cu/YSZ cathode by oxidation, but it this is compensated offset for by a favorable thermal expansion coefficient. Therefore, Cu/YSZ cermet can be adequately used as a suitable cathode material of in high high-temperature electrolysis.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.257-268
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• 2024

Hydrogen serves as a clean energy source with potential applications across various sectors including electricity, transportation, and industry. In terms of policy and economic support, governmental policy backing and economic incentives are poised to accelerate the commercialization and expansion of hydrogen energy technologies. Hydrogen energy is set to become a cornerstone for a sustainable future energy system. Additionally, when constructing hydrogen production plants, economic aspects must be considered. The essence of hydrogen production plants lies in the electrolysis of water, a process that separates water into hydrogen and oxygen using electrical energy. The initial capital expenditure (CAPEX) for hydrogen production plants can vary depending on the electrolysis technology employed. This study aims to provide a comprehensive understanding of hydrogen production technologies as well as to propose a method for predicting the CAPEX of hydrogen production plants.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1385-1391
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• 2015

A water reuse system was designed for a demonstration plant by combining fiber filtration and electrolysis. A discharged dye wastewater after treated with biomedia was used in this study. It was found that an additional removal of suspended solids (SS) was feasible with 2-stage filtration while electrolysis was not effective. Also, $COD_{cr}$ and $COD_{Mn}$ were not removed with 2 -stage filtration but electrolysis resulted in about 26.9% additional removal. This indicates that electrolysis play an important role in organic removal. Removal of T-N and T-P was negligible with 1 and 2-stage fiber filtration and low-level electrolyte. However, with 2000 ppm of electrolyte, their removal efficiencies were about 83.1 and 60%, respectively, suggesting that the removal rates are well associated with the electrolyte concentrations. With high-level electrolyte, colority was removed about 82% while chlorine ions were removed only about 10%. Therefore, to treat underground water containing high-level salinity in the follow-up study, based on the results in this paper, a combined system with selection of additional unit process and reverse osmosis will be designed.