• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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• pp.150-158
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• 2005

Added ratio of 8YSZ powder and organic compounds (solvent, plasticizer, dispersant, binder) properly. It manufactured electrolysis membrane by wet process that make slurry and dry process that do not use organic compounds. In the case of wet process, harmony combination and method of organic compound are an importance element in slurry manufacture. This slurry did calcine at temperature of 140$^{\circ}C$ in Furnace and manufactured electrolyte disk by Dry pressing method. Like this, manufacturing disk sintered at temperature of $1300^{\circ}C,\;1400^{\circ},\;1500^{\circ}C$ in Furnace and completed electrolysis membrane. Confirmed change of crystal structure and decision form through analysis of density, SEM, XRD according to change of sintering temperature, and considered relation with ion conductivity.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.445-452
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• 2008

DME(Dimethyl ether) Dimethyl Ether (DME) is a new clean fuel and an environmental-benign energy resource. In comparison with other fuels, DME rapidly decomposes into carbon dioxide ($CO_2$) and water in the atmosphere without forming ozone. It can be manufactured from various energy sources including natural gas, coal, biomass and spent plastics. In addition to its environmentally friendly properties, DME is considered as one of the most promising candidates for the substitute of LPG and diesel fuel. In this work, we will be studied to find optimized condition for the catalyst of DME energy manufacture from hydrogen and carbon oxide and its chemical and physical characteristics.

• Transactions of Materials Processing
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• v.28 no.5
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• pp.266-274
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• 2019

Metal sealing is used to connecting the parts between valves and fuel pipes for a FCEV which utilizes hydrogen gas of 700 bar. Instead of general carbon steel, stainless steel is the primary material used to manufacture fuel pipes due to hydrogen embrittlement. The shape of deformation between metals is an important factor on the air-tightness of the metal to metal contact. Since the stainless steel pipe is hardened using the plastic forming during the tip shaping stage, this work hardening could have an effect on the deformed shape and characteristics of contact surfaces in fastening of pipes. In this paper, the deformation history of the pipe model was considered in order to analyze the hydrogen-tightness on the metal sealing part. The contact distance and the forward displacement for fastening were compared using experimental results and the simulation results. The simulation of the effect of material change on the fitting body demonstrated that the hardness or the strength of the formed tip of the pipe was designed to a proper valued level since the characteristics of the contact surface was exhibited better when the strength of the pipe was lower than that of the fitting body.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.961-968
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• 2022

Hydrogen embrittlement leads to the damages in bolts, nut, especially, high pressure valves, in the semiconductor facilities, hydrogen vehicles, hydrogen stations and so on. Monel material has higher strength than SUS material. Therefore, even though Monel material with special alloy is usually used to prevent the hydrogen embrittlement, it needs powerful drawing system to manufacture the rectangular or hexagonal bar using circular bar. The purpose of this study is to investigate the characteristics of plastic deformation of Monel material and 2 rollers of rolling unit in plastic limit through numerical analysis. As the results, it was predicted that, based on mean stress, as the rolling step was increased, the rolling force of rolling unit was decreased. In addition, the heat treatment for Monel material was needed because of residual stress due to plastic deformation. As for rollers, the roller was safe about 1.86 times compared with that of ultimate strength. In this study, as the roller 2 showed larger stress than roller 1, thus, roller 2 should be designed carefully to guarantee the safety. Further it was confirmed that the reaction force of roller could be helpful in bearing design.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.290-294
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• 2023

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillage and wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of less than 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanent brain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gases is extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors that have been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture and mass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemical sensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide, an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fast response time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensors depend on imports. Although domestic technologies and products exist, more research is required on their long-term stability and reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristic evaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivity of the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counter electrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was also deposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuring concentrations as low as 0.6 ppm was developed.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.3
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• pp.232-238
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• 2008

Research has been proceeded on fuel cell which is fueled by hydrogen. Polymer electrolyte membrane fuel cell (PEMFC) is promising power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, temperature dependent performance. These problems could be solved by experiment which is useful for analysis and optimization of fuel cell performance and heat management. In this paper, when hydrogen flows constantly at the stoichiometry of ${\xi}=1.6$, the performance of the fuel cell stack was increased and the voltage difference between each cells was decreased according to the increase of air stoichiometry by 2.0, 2.5, 3.0. Therefore, the control of air flow rate in the same gas channel is important to get higher performance. Purpose of this research is to expect operation temperature, flow rate, performance and mass transportation through experiment and to help actual manufacture of PEM fuel cell stack.

• Journal of the Korean institute of surface engineering
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• v.56 no.6
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• pp.412-419
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• 2023

Anion exchange membrane electrolysis is considered a promising next-generation hydrogen production technology that can produce low-cost, clean hydrogen. However, anion exchange membrane electrolysis technology is in its early stages of development and requires intensive research on electrodes, which are a key component of the catalyst-system interface. In this study, we optimized the pressure conditions of the hot-pressing process to manufacture cobalt oxide electrodes for the development of a high uniformity and high adhesion electrode production process for the oxygen evolution reaction. As the pressure increased, the reduction of pores within the electrode and increased densification of catalytic particles led to the formation of a uniform electrode surface. The cobalt oxide electrode optimized for pressure conditions exhibited improved catalytic activity and durability. The optimized electrode was used as the anode in an AEMWE single cell, exhibiting a current density of 1.53 A cm^-2 at a cell voltage of 1.85 V. In a durability test conducted for 100 h at a constant current density of 500 mA cm^-2, it demonstrated excellent durability with a low degradation rate of 15.9 mV kh^-1, maintaining 99% of its initial performance.

• Air Cleaning Technology
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• v.23 no.3
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• pp.34-43
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• 2010

In most productive facility of pharmaceutical companies, the fumigation using formaldehyde gas has been put into operation. Because formaldehyde gas is so bactericidal as to sterilize bacterial spore which can not be sterilized with usual disinfectants, it has been used for fumigation in many facilities such as facility of experimental animals, research institute and productive facility of pharmaceutical companies which are required to be high level of biological clean. However, the use of formaldehyde is recently under the strict management because of its causing of sick house and carcinogenesis. We introduce the conditions of sterilization using formaldehyde gas, the examples of sterilization using formaldehyde gas in a pharmaceutical manufacture and the problems of use of formaldehyde against environments and health. Further, we describe the characteristics and future subjects of the sterilization method using gasified oxidants such as hydrogen peroxide, peracetic acid and chlorine oxide.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.612-617
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• 2021

In the case of a metal sulfide electrode, it is used as an anode or cathode active material in a lithium battery. The reason is that the voltage exists between 0.8 and 2.0 V via lithium electrode and the discharge and charge capacity is high. In order to manufacture nickel sulfide for electrode, which are widely used, nano-nickel powder was sulfided using ammonium polysulfide, and single-phase NiS electrodes were manufactured through heat treatment. The prepared NiS electrode had a high initial capacity of 500 mAh/g or more, and was stabilized after 20 cycles to maintain a capacity of 400 mAh/g or more until 100 cycles.

• Resources Recycling
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• v.27 no.5
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• pp.30-37
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• 2018

For recylcing of high purity tantalum (Ta) scrap, We investigated manufacture of tantalum powder using hydride-dehydride (HDH) process. Tantalum had excellent properties such as ductile, hardness and high melting point. Usually these properties made difficult to make a powder. In this study, Tantalum powder was manufactured using Tantalum hydride via hydridation. Tantalum hydride was formed at $500^{\circ}C$, 5 hr/$700^{\circ}C$, 3 hr and it is easy to make a tantalum hydride powder because hydrogen in the tantalum act as a defect dislocation and lattice expansion. The powder was pulverized to a size of less than $10{\mu}m$ under a condition of 1300 rpm, 30 min using a ring mill, and tantalum powder with less than 50 ppm hydrogen was prepared through dehydridation in an Ar and low vacuum atmosphere.