• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.337-337
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• 2004

As one of researches for the P ＆ T purposes, a basic experiment on the recovery of actinide elements from the mixture with rare earth elements by means of electrorefining using a liquid cadmium cathode in the LiCl-KC1 eutectic melt was carried out. In order to examine the behaviors of electrodeposition of metal ions on a liquid electrode, recovery experiments of rare earth metals resulting from forming electrodeposits were performed by a galvanostatic electrolysis method at various current densities. A cyclic voltammetric technique was applied to determine reduction-oxidation potential of each metal element in the melt and to detect the changes of the multi component melt composition for on-line monitoring. Also, a collaboration study with RIAR was completed to test the preliminary feasibility on a recovery of actinide elements from the mixture with rare earth elements using a liquid cadmium cathode and actinide metals. Experimental results showed that the ratio of actinides to rare earths, 9: 0.5∼1 led to the rare earth content of about 5∼10 wt% in the deposit.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.845-850
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• 2009

Bioethanol derived from lignocellulosic biomass has the potential to replace gasoline. Cellulose is naturally recalcitrant to enzymatic attack, and it also surrounded by the matrix of xylan and lignin, which enhances the recalcitrance. Therefore, lignocellulosic materials must be pretreated to make the cellulose easily degraded into sugars and further fermented to ethanol. In this work, hydrothermal pretreatment on corn stover at $195^{\circ}C$ for 15 min with and without lower concentration of formic acid was compared in terms of sugar recoveries and ethanol fermentation. For pretreatment with formic acid, the overall glucan recovery was 89% and pretreatment without formic acid yielded the recovery of 94%. Compared with glucan, xylan was more sensitive to the pretreatment condition. The lowest xylan recovery of 55% was obtained after pretreatment with formic acid and the highest of 75% found following pretreatment without formic acid. Toxicity tests of liquor parts showed that there were no inhibitions found for both pretreatment conditions. After simultaneous saccharification and fermentation (SSF) of the pretreated corn stover with Baker's yeast, the highest ethanol yield of 76.5% of the theoretical was observed from corn stover pretreated at $195^{\circ}C$ for 15 min with formic acid.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.51-52
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• 2018

Selective oxidation of RE elements from the U/RE metal ingot was studied in this paper using electrochemical process. Constant potential of -1.7V was applied between anode and cathode, where the potential value corresponds to standard potentials between actinide and rare earth materials. When the current values approached to nearly 0 mA, the reaction was finished. It is confirmed from the EPMA analysis that only U part of the U/RE ingot was remained. The metal recovered to the zinc cathode was obtained through the distillation process and it is being chemically analyzed in the KAERI analytical laboratory.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.132-133
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• 2021

In recent years, energy harvesting from natural sources and waste heat has been attracting more attention from researchers in response to ever-growing energy demands, high energy prices, and climate-change-mitigation purposes. It is also an important step towards future sustainable energy usages. In thermal dynamic cycles, expanders are playing as the most important equipment for waste heat recovery and energy harvesting as well. As a kind of expander, the bladeless turbine has a promising future and more widely using owning its advantages on relatively long life, good off-design performance, easy operation cleaning and maintenance, a simple structure, no blade corrosion, and low manufacturing costs. There are numerous studies about using the Tesla Turbine as a key technology for energy harvesting in a wide range of applications and conditions. They are presented to help identify technologies that have sufficient potential for applicating to our life and marine industrial engineering. This review paper, initially, presents an overview of current studies both theoretical and experimental of Tesla Turbine usage for waste heat recovery alongside its challenges and investigation on the effect of its configuration, working fluid selection as well. To conclude, future perspectives besides possible ways of transforming waste heat energy to electricity or work, which leads to circular energy, are discussed. The ambition of this paper is to act as a first-hand reference, through the well-defined possible directions, to the young researchers and senior scientists.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.674-680
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• 2023

The brine and seawater are important and largely untapped sources of critical trace metals and elements. The coupling of selective recovery of trace metals from seawater/brine with desalination plants gives an added advantage of energy credits to desalination plants and as well as reduce the cost of desalinated water. In this paper, status review on recovery of important trace metals and other alkali metals from seawater is presented. The potential of Indian desalination plants for recovery of trace metals, based on recovery ratio of 0.35 is also highlighted. Studies carried out by the process based on adsorption using Radiation Induced Grafted (RIG) polymeric adsorbents and then fractional elutions are presented. The fouling factors due to bio fouling and dirt fouling have been estimated for various locations of interest through field trails. The pay loader in the form of compact Contactor Assembly with minimum pressure drop, for loading specially designed radiation grafted sorbent in leaflet form has been briefed, as required for plant scale facility. The typical conceptual process design details of farm assembly of project CRUDE are described.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.3-32
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• 2008

The potential deep geothermal resources span a wide range of heat sources from the earth, including not only the more easily developed, currently economic hydrothermal resources; but also the earth's deeper, stored thermal energy, which is present anywhere. At shallow depths of 3,000~10,000m, the coincidence of substantial amounts heat in hot rock, fluids that heat up while flowing through the rock and permeability of connected fractures can result in natural hot water reservoirs. Although conventional hydrothermal resources which contain sufficient fluids at high temperatures and geo-pressures are used effectively for both electric and nonelectric applications in the world, they are somewhat limited in their location and ultimate potential for supplying electricity. A large portion of the world's geothermal resource base consists of hot dry rock(HDR) with limited permeability and porosity, an inadquate recharge of fluids and/or insufficient water for heat transport. An alternative known as engineered or enhanced geothermal systems(EGS), to dependence on naturally occurring hydrothermal reservoirs involves human intervention to engineer hydrothermal reservoirs in hot rocks for commercial use. Therefore EGS resources are with enormous potential for primary energy recovery using an engineered heat mining technology, which is designed to extract and utilize the earth's stored inexthermal energy. Because EGS resources have a large potential for the long term, United States focused his effort to provide 100GW of 24-hour-a-day base load electric-generating capacity by 2050.

• Resources Recycling
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• v.31 no.4
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• pp.34-39
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• 2022

In this study, effects of ultrasonic energy on the cementation reaction and copper recovery rate were investigated for different types of iron samples, such as plate, chip, and powder, for recovering copper from waste etchant, which contained ~3.5% copper. The cementation reaction using the ultrasonic energy was more effective than the simple stirring reaction, with the former exhibiting a high copper recovery rate than the latter for the same time interval. When cementation was performed for 25 min with ultrasonic treatment, rather than simple stirring, the copper recovery rate of the plate, chip, and powder improved from 7.0% to 12.0%, 14.0% to 46.1%, and 41.9% to 77.2%, respectively. Therefore, the use of ultrasonic energy could detach the copper recovered by the cementation reaction from the surface of the iron samples, thereby increasing the copper recovery rate. Owing to the use of ultrasonic energy, the copper recovery rate increased by 2-6 times, and the recovered copper exhibited a decreased particle size compared to that obtained via simple stirring.

• Analytical Science and Technology
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• v.16 no.3
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• pp.191-197
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• 2003

Two methods, IDMS (Isotope Dilution Mass Spectrometry) and controlled potential coulometry are compared by the determination of Pu for the NBL, CRM No.122, $PuO_2$. The recovery of Pu was found to be $1.002176{\pm}0.000452$ within the relative standard deviation of 0.045% (95% conf. level) although a small size of sample ($0.9{\mu}g$-Pu) was used in IDMS. The recovery using controlled potential coulometry were obtained in the range of 0.9923~0.9960. The analytical results of IDMS and controlled potential coulometry were good agreement within 0.6~1%. Base on these experiment results, The plutonium in HANARO irradiated fuel rod that separated portion of top, middle, and bottom were determined. The measured values of Pu are 1.155 mg, 2.483 mg and 1.920 mg in one gram of sample(fuel+clad), respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.156-161
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• 2012

Marine biomass is considered an important substrate for anaerobic digestion to recovery energy i.e. methane. Nevertheless, marine biomass has attracted little attention by researchers compared to terrestrial feedstock for anaerobic digestion. In this study, biochemical methane potential (BMP) test was used to evaluate generation of renewable energy from starfish. A cumulative biogas yield of $748{\pm}67mL\;g^{-1}VS^{-1}$ was obtained after 60 days of digestion. The cumulative methane yield of $486{\pm}28mL\;CH_4\;g^{-1}VS^{-1}$ was obtained after 60 days of digestion. The methane content of the biogas was approximately 70%. The calculated data applying the modified Gompertz equation for the cumulative $CH_4$ production showed good correlation with the experimental result obtained from this batch study. Since the result obtained from this study is comparable to results with other substrates, marine biomass can be co-digested with food waste or swine wastewater to produce $CH_4$ gas that will help to reduce the gap in global energy demand.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.753-761
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• 2016

Liquid-liquid extraction (LLE) can be used for the recovery of acetic acid from black liquor prior to bioethanol fermentation. Recovery of value-added chemicals such as acetic-, formic- and lactic acid using LLE from Kraft black liquor was studied. Acetic acid and formic acid have been reported to be strong inhibitors in fermentation. The study elucidates the effect of three reaction parameters: pH (0.5~3.5), temperature ($25{\sim}65^{\circ}C$), and reaction time (24~48 min). Extraction performance using tri-n-octylphosphine oxide as the extractant was evaluated. The maximum acetic acid concentration achieved from hydrolyzates was 69.87% at $25^{\circ}C$, pH= 0.5, and 36 min. Factorial design was used to study the effects of pH, temperature, and reaction time on the maximum inhibitor extraction yield after LLE. The maximum potential extraction yield of acetic acid was 70.4% at $25.8^{\circ}C$, pH=0.6 and 37.2 min residence time.