• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.39-46
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• 2014

Our lab designs a heat exchangers for hydrogen gas. Coolant is water, thus it is very difficult to determine heat transfer parameters in this gas-liquid system. Repeated experiments gives overdesign value 6.06%, overall heat transfer coefficient 36.32 ($kcal/m^2-hr-^{\circ}C$) for Hydrogen. Theoretically determined overall heat transfer coefficient is 38.44 ($kcal/m^2-hr-^{\circ}C$). Our lab simulated this system and overdesign 30.4% shows good match with this experiment by HTRI. These parameters are in same range with literature.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.17-24
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• 2000

The peroxidase activity was localized cytochemically to get an insight into its precise function in lignin biosynthesis. In this work, cerium chloride ($CeCl_3$) was used as a trapping agent for hydrogen peroxide ($H_2O_2$) generated from peroxidase. Seasonal variation of peroxidase activities in cambial region of Populus, Pinus, and Ginkgo was investigated at subcellular levels. Under transmission electron microscopy, electron dense deposits of cerium perhydroxide formed by reaction with $H_2O_2$ were observed in cambium and its immediate derivatives. The staining with $CeCl_3$ in cambium varied with growth seasons. The strongest $H_2O_2$ accumulation, regardless of tree species, appeared in May. Staining pattern of $CeCl_3$ in the cambium of poplar indicated that the production of peroxidase started in March before the opening of buds and reached the highest in May and then declined in August. Ginkgo and Pinus showed relatively late generation of $H_2O_2$ production when compared with Populus. Although Ginkgo and Pinus are classified into gymnosperms, however, the generation of peroxidase production and its duration was different from each other. Little staining appeared in all the tree samples collected in September before falling the leaves.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.124.2-124.2
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• 2010

Generally, a coolant of the nuclear power plant is manufactured by electrolyzing the sea water near the plant for making the sodium hypochlorite(NaOCl), which is used for sterilizing the bacteria and the shellfishes sticking to the drains or the pumps at the outlet of the cooling system due to $8-10^{\circ}C$ warmer temperature than the inlet sea water. During manufacturing the sodium hypochlorite, the hydrogen with the high purity is also produced at the anode side of the electrolyzer. This paper describes a novel power plant system combined with the polymer electrolyte membrane(PEM) fuel cell, the wasted hydrogen from the sea water electrolyzer and the wasted heat of the nuclear power plant. The present status over the exhausted hydrogen at twenty nuclear power plants in Korea was investigated in this study, from which an available power generation is estimated. Furthermore, the economic feasibility of the PEM fuel cell power plant is also evaluated by a current regulations over the power production and exchange using a renewable energy shown in Korea Power Exchange(KRX).

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1167-1168
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• 2006

Recently, the concern for environmental issue has been rising in the world such as global warming and breaking of ozone barrier by exhausting carbon dioxide(CO2) and Freon. In this situation, Photovoltaic(PV) and hydrogen energy system for utilizing clean and renewable energy was highlighted to contribute very much against the global warming prevention. Until now, authors have studied EMTDC model Development of Solar-powered Hydrogen production system and manufactured the 600W class actual PV-SPE system. Which was established in 2004 to produce highly pure hydrogen energized by PV power generation system. Sooner, authors will establish 100kW class PV-SPE system. Economically, this system produce large amount of hydrogen. In this paper, all data of 100kW class PV-SPE system will be simulated by using PSCAD/EMTDC.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.3-6
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• 2004

Industrial gas separation by membranes began in 1980 with the introduction of hollow-fiber polysulfone membrane systems by Permea, at that time a division of Monsanto. This first application was the recovery of hydrogen from ammonia reactor purge gas and was soon followed by the generation of nitrogen from air. Today, membrane gas separation ranks second behind cryogenic distillation in terms of nitrogen production, and this application has drawn the industrial gas companies into the membrane field.(omitted)

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.34-50
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• 2022

Since the Paris climate agreement, reducing greenhouse gases has been the most important global issue. In particular, it is necessary to reduce fossil fuels in the mobility sector, which accounts for a significant portion of total greenhouse gas emissions. In this paper, we investigated the economic feasibility of green mobility energy supply chains, which supply hydrogen as fuel to hydrogen vehicles based on electricity from renewable energy sources. The design and operation costs were analyzed by evaluating nine scenarios representing various combinatorial possibilities such as renewable energy generation, hydrogen production through water electrolytes, hydrogen storage and hydrogen refueling stations. Simulation calculations were made using Homer Pro, widely used commercial software in the field. The experience gained in this study could be further utilized to construct actual hydrogen energy systems.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.601-609
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• 2017

Hydrogen is a clean, endlessly produced energy and it is easy to store and transfer. So, hydrogen is regarded as next generation energy. Among various ways for hydrogen production, the way to produce hydrogen by water electrolysis can effectively respond to fossil fuel's depletion or climate change. As interest in hydrogen has increased, related research has been actively conducted in many countries. In this study, we analyzed the performance characteristics and safety of water electrolysis system. In this study, we analyzed the performance characteristics and safety of water electrolysis system. The items for safety performance evaluation of the water electrolysis system were derived through analysis of international regulations, codes, and standards on hydrogen. Also, a prototype of the overall safety performance evaluation station was designed and developed. The demonstration test was performed with a prototype $10Nm^3/h$ class water electrolysis system that operated stably under various pressure conditions while measuring the stack and system efficiency. At 0.7MPa, the efficiency of the alkaline water electrolysis stack and the system that used in this study was 76.3% and 49.8% respectively. Through the GC analysis in produced $H_2$, the $N_2$ (5,157ppm) and $O_2$ (1,646 ppm) among Ar, $O_2$, $N_2$, CO and $CO_2$ confirmed as main impurities. It can be possible that the result of this study can apply to establish the safety standards for the hydrogen production system by water electrolysis.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2670-2677
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• 2023

In the nuclear safety studies, a new trend refers to the evaluation of uncertainties as a mandatory component of best-estimate safety analysis which is a modern and technically consistent approach being known as BEPU (Best Estimate Plus Uncertainty). The major objectives of this study consist in performing a study of uncertainties/sensitivities of the major analysis results for a generic CANDU 6 Nuclear Power Plant during Station Blackout (SBO) progression to understand and characterize the sources of uncertainties and their effects on the key figure-of-merits (FOMs) predictions in severe accidents (SA). The FOMs of interest are hydrogen mass generation and event timings such as the first fuel channel failure time, beginning of the core disassembly time, core collapse time and calandria vessel failure time. The outcomes of the study, will allow an improvement of capabilities and expertise to perform uncertainty and sensitivity analysis with severe accident codes for CANDU 6 Nuclear Power Plant.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.3
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• pp.230-237
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• 2007

Titania nanotube(TiNT) and CdS sol were synthesized by hydrothermal reaction under strongly basic condition and by precipitation reaction of $Cd(N0_3)_2$ and $Na_2S$ aqueous solutions, respectively. After preparing a series of CdS-TiNT composite films on $F:SnO_2$ conducting glass with variation of the mole ratio (r) of TiNT/(CdS+TiNT), their visible light absorption, photocatalytic activities for hydrogen production, and the photocurrent generation were examined. In general, this CdS-TiNT series showed lower photocatalytic activities and photocurrent generation under Xe light irradiation compared to their counterparts, i.e., CdS-$TiO_2$ particulate series. It appeared that TiNTs are not so effective photocatalyic material in spite of their larger specific surface areas compared to $TiO_2$ nanoparticles, because they indicate a poor crystallinity and less intimate interaction or contact with CdS particles owing to the tubular morphology and an easy agglomeration among themselves.