• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.1-10
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• 2024

In this study, we constructed a process simulation model for an agricultural by-products based Solid Oxide Fuel Cell (SOFC) combined heat and power generation system as part of the introduction of technology for energy self-sufficiency in the agricultural sector. The aim was to reduce the burden of increasing fuel and electricity consumption due to rapid fluctuations in international oil prices and the expansion of smart farming in domestic farms, while contributing to the national greenhouse gas reduction goals. Based on the experimental results of 0.3 ton/day torrefied agricultural by-product gasification experiment, a model for an agricultural by-product-based SOFC cogeneration system was constructed, and optimization of the heat exchange network was conducted for SOFC capacities ranging from 4 to 20 kW. The results indicated that an 8 kW agricultural by-product-based SOFC cogeneration system was optimal under the current system conditions. It is anticipated that these research findings can serve as foundational data for future commercial facility design.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.608-613
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• 2019

The purpose of the present study is to analyze and evaluate the performance of a small Darrieus wind turbine installed at the Urumsil region of Deokjeok-do Island in the west of South Korea 50 km away from Incheon. This place has no government electricity so alternate resources of energy needed to be installed there. For this purpose a small Darrieus wind turbine with the capacity of 1.5 kW was developed and installed at the site. The experimental power output of the wind turbine is less than the designed power at the same values of wind speed. This power loss is mainly due to the highly unsteady nature wind of sudden changes in magnitude of wind speed and wind angle. The results of current study can be used to make a future power generation plan for Deokjeok-do and other nearby small islands.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.1
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• pp.1-10
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• 2021

Water electrolysis technology, which generates hydrogen using renewable energy resources, has recently attracted great attention. Especially, the polymer electrolyte membrane water electrolysis system has several advantages over other water electrolysis technologies, such as high efficiency, low operating temperature, and optimal operating point. Since research that analyzes performance characteristics using test bench have high cost and long test time, however, model based approach is very important. Therefore, in this study, a system model for water electrolysis dynamics of a polymer electrolyte membrane was developed based on MATLAB/Simulink®. The water electrolysis system developed in this study can take into account the heat and mass transfer characteristics in the cell with the load variation. In particular, the performance of the system according to the stack temperature control can be analyzed and evaluated. As a result, the developed water electrolysis system can analyze water pump dynamics and hydrogen generation according to temperature dynamics by reflecting the dynamics of temperature.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.1-7
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• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.415-423
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• 2007

Photocatalytic water splitting (PWS) is the most promising technology to produce $H_2$ energy directly from renewable water and solar light. In spite of the remarkable progress made in the last decade, there are still many technical challenges remaining particularly in finding new photocatalytic materials with high efficiency and durability. This article discusses the application of nanocomposite materials in search of new photocatalytic materials for solar hydrogen production from water. It has been demonstrated that smart combination and modification of known materials and functions could be fruitful approach for the purpose.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.77-83
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• 2013

In this study, we aimed to determine the optical properties of the plasma used for the dry cleaning method. The optical properties of the atmospheric pressure plasma device were measured through the degree of ionization of hydrogen or nitrogen gas by ionized atmospheric gas. The degree of ionization of hydrogen or nitrogen is closely associated with surface modification. We observed through our experiments that argon gas, an atmospheric gas, caused an increase in the ionization of nitrogen gas, which has similar ionization energy. This type of increase in nitrogen gas ions is believed to affect surface modification. The results of our study show that the pressure of argon gas and the partial pressure of argon and nitrogen gases lead to different results. This important result shows that argon ions can affect the ionization of nitrogen gas.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.343-352
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• 2022

Co/Al₂O₃ nanopowder was used as a catalyst to investigate the effect of catalyst support, reduction temperature, sodium borohydride (NaBH₄) concentration, sodium hydroxide (NaOH) concentration, and reaction temperature on the characteristics of NaBH₄ hydrolysis. The Co/Al₂O₃ nanopowder showed a high catalytic activity among various catalysts. Catalyst reduction at 250℃ exhibited a relatively good activity. The activity decreased with an increase in the NaBH₄ concentration. Conversely, the activity increased and then decreased with an increase in the NaOH concentration. Additionally, the activity increased with an increase in the reaction temperature. The value of apparent activation energy was 40.81 kJ/mol, which was lower than the other Co-based catalysts. Thus, Co/Al₂O₃ nanopowder catalyst can be widely used for NaBH₄ hydrolysis owing to its superior catalytic activity.

• Composites Research
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• v.36 no.5
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• pp.377-382
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• 2023

To enhance the performance of graphene-based devices, it is of great importance to better understand the interfacial interaction of graphene with its underlying substrates. In this study, the adhesion energy of monolayer graphene placed on dielectric substrates was characterized using mode I fracture tests. Large-area monolayer graphene was synthesized on copper foil using chemical vapor deposition (CVD) with methane and hydrogen. The synthesized graphene was placed on target dielectric substrates using polymer-assisted wet transfer technique. The monolayer graphene placed on a substrate was mechanically delaminated from the dielectric substrate by mode I fracture tests using double cantilever beam configuration. The obtained force-displacement curves were analyzed to estimate the adhesion energies, showing 1.13 ± 0.12 J/m² for silicon dioxide and 2.90 ± 0.08 J/m² for silicon nitride. This work provides the quantitative measurement of the interfacial interactions of CVD-grown graphene with dielectric substrates.

• Journal of Internet Computing and Services
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• v.24 no.6
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• pp.171-180
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• 2023

Hydrogen energy technology is gaining importance in the era of the Fourth Industrial Revolution, offering military advantages when applied to military vehicles due to its characteristics such as reduced greenhouse gas emissions, noise, and low vibration. Korea's military has initiated the Army Tiger 4.0 plan, focusing on hydrogen application, downsizing, and AI-based smart features. The Ministry of National Defense plans to collaborate with the Ministry of Environment to expand hydrogen charging stations nationwide, anticipating increased deployment of military hydrogen vehicles. However, considering the Jet Fire and VCE(Vapor Cloud Explosion) nature of hydrogen, ensuring safety during installation is crucial. Current military guidelines specify a minimum safety distance of 2m from adjacent buildings for charging stations. Scientific methods have been employed to quantitatively assess the accident damage range of hydrogen, proposing a minimum safety distance beyond the affected area.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.97-104
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• 2018

3-dimensional temperature distribution of the exhaust gas of a fire flame of LPG have been measured by the constructed CT-TDLAS system. 3-Dimensional temperature distributions are measured by 2 layers of CT-TDLAS. Each layer has $8{\times}8$ laser beams implying the temperatures of 64 meshes are measured. SMART algorithm has been adopted for reconstructing the absorption coefficients on the meshes. The line strengths at 6 representative wave lengths of $H_2O$ have been used for obtaining the absorption spectra of the exhaust gas. The temperature distributions measured by the constructed CT-TDLAS have been compared with those by the thermocouples. The relative errors measured between by thermocouple and CT-TDLAS were 13% in average and 33% at maximum. The similarity of temperature distribution between by thermocouples and by CT-TDLAS has been shown at the lower layer than the upper layer implying an unstability of combustions.