• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.3
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• pp.34-40
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• 2000

A multisample extraction device was newly designed for efficient extraction of dissolved lipophillic organic compounds from sea water sample. This device allowed extraction of organic compounds from up to 96 sample at a time using 96 multifolder on the principle of solid phase extraction with commercially available octadecyl silane (ODS) cartridges. The recovery yield of the new divice was higher than 90 % while that of conventional liquid-liquid extraction process are only 60 - 70 %. The amount of solvent required for the new device could be reduced to less than 20㎖ per 1ℓ of sample while 1 - 2 ℓ of solvent were used in the conventional liquid-liquid extraction process. The usefulness of this novel method was demonstrated with sea water samples collected from Yellow sea, and the qualitative and quantitative analyses results of the dissolved hydrocarbon showed this method was superior to that of conventional liquid-liquid extraction process in efficiency and reliability.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.595-602
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• 2012

In this study, for the purpose of reduction of $CO_2$ gas emission and to increase recovery of waste heat from ships, the ORC (Organic Rankine Cycle) is investigated and offered for the conversion of temperature heat to electricity from waste heat energy from ships. Simulation was performed with waste heat from the exhaust gasse which is relatively high temperature and cooling sea water which is relatively low temperature from ships. Various fluid is used for simulation of the ORC system with variable temperature and flow condition and efficiency of system and output power is compared. Finally, 2,400kW output power is obtained by system optimization of the preheater and reheater utilizing waste heat form sea water cooling system.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.307-312
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• 2023

In this study, a catalytic oxidation-heat recovery system was designed that can remove unreacted with a concentration of about 1% to 6% in the exhaust gas of hydrogen fuel cells and recover heat to ensure safety in the hydrogen economy. The safety system was devised by filling hydrogen oxidation catalysts at room temperature that can remove unreacted hydrogen without any energy source, and an exhaust-heat recovery device was integrated to efficiently recover the heat released from the oxidation reaction. Through CFD analysis, variations in pressure and fluid within the system were shown depending on the filling conditions of the hydrogen oxidation system. In addition, it was found that waste heat could be recovered by optimizing the temperature of the exhaust gas, flow rate, and pressure conditions within the heat recovery system and securing hot water above 40 ℃ by utilizing the exhaust gas oxidation heat source above 300 ℃. Through this study, it was possible to confirm the potential of utilizing hydrogen processes, which are applied in small to medium-sized systems such as hydrogen fuel cells, as a safety system by evaluating them at a pilot scale. Additionally, it could be a safety guideline for responding to unexpected hydrogen safety accidents through further pilot-scale studies.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.435-450
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• 2006

Free electron lasers (FELs) are promising sources of coherent radiation that can provide users with radiations having a wide-range frequency-tunability and good spectral characteristics for basic science and industrial applications. Especially in Terahertz or X-ray ranges of spectrum, FELs can generate much stronger radiations than conventional light sources. In this paper, we introduce the working principles and key technologies of FELs, the status and the prospects of FEL developments.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.273-279
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• 2008

The purpose of this study is not only to evaluate thermal performance but also to find the stress behavior of heat transfer tubes under the part load operation in Heat Recovery Steam Generator. Flow analysis was performed to know the behavior of exhaust gas from gas turbine and thermal performance was calculated using distribution of hot exhaust velocity. In addition, tubes temperature during operation were gathered from actual plant to verify the uneven flow distribution under part load operation. Stress analysis was performed using tubes temperature data gathered from actual plant under both part and full load operations to know the stress behavior of tubes.

• Resources Recycling
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• v.30 no.6
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• pp.61-67
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• 2021

This work investigated the cementation of iridium from iridium-containing hydrochloric acid leachate. Zinc powder was used as the reducing agent, and the effects of the stoichiometric ratio of Zn/Ir, initial Ir concentration, initial pH, reaction time, and ultrasound irradiation on iridium recovery were investigated. When only the stirrer was used for cementation, the iridium recovery increased with the addition amount of zinc, and the recovery of about 70% at 40 times the stoichiometric ratio of Zn/Ir. In contrast, when employing ultrasonic irradiation with stirring, the recovery of iridium decreased at 20 times or less the stoichiometric amount of zinc. The recovery of iridium increased at 40 times the stoichiometric ratio of Zn/Ir. This result may be due to the ionization of zinc and re-dissolution of iridium during the ultrasound irradiation treatment. When a combination of ultrasonic irradiation and stirring was used for cementation, the iridium recovery increased by more than 27% compared to that when using only the stirrer. It was possible to recover 99% of iridium under the following conditions: reaction time, 60 min; initial pH, 0.01; volume of leachate, 100 mL; 1770 ppm Ir, 40 times the stoichiometric ratio of Zn/Ir.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.825-828
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• 2009

고형원료인 폐기물의 감량화 및 자원화 기술 중 가장 대표적인 기술로 폐기물의 소각(incineration)기술과 가스화(gasification)용융기술을 들 수 있다. 폐기물 가스화 기술은 폐기물 내의 탄소, 수소 성분을 가스화하여 CO, $H_2$가 주성분인 합성가스(synthesis gas, syngas)로 전환하여 불연물은 용융되어 환경적으로 무해한 슬래그로 회수하는 기술이다. 폐기물 가스화 용융 시스템으로 발생된 합성가스를 재순환하여 사용하는 합성가스 재순환시스템을 통해 가스화에 필요한 열을 시스템 내에서 대체하여 사용하는 기술개발은 폐기물 가스화 용융기술의 경제성을 높일 수 있다. 본 연구에서는 고형 폐기물 가스화반응에 의해 발생되는 합성가스를 재순환하여 폐기물 가스화 용융 시스템내의 자체 에너지원으로 활용할 수 있도록 하는 합성가스 재순환 시스템 및 버너의 운전특성을 고찰하였다. 합성가스의 재순환 장치에서의 운전 압력 제어 및 유량제어를 통해서 안정적인 합성가스 재순환 성능과 재순환버너의 연소 성능을 유지할 수 있었다. 합성가스 재순환버너에 의한 16,800 $kcal/Nm^3$ 조건 및 33,600 $kcal/Nm^3$ 조건에서 운전시에도 가스화기의 운전온도는 안정적으로 유지됨에 따라 생산된 합성가스의 가스화기 보조연료 대체 및 에너지절감이 가능한 것으로 판단된다.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.224-230
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• 2011

For developing high performance fuel cell, peripheral devices and key components have to be studied in priority. In this study, centrifugal pump was studied for heat recovery. For PEM fuel cell system, a four-impeller centrifugal pump was designed, tested and compared with result of commercial product (IWAKI). In addition, effects of number of impeller were analyzed by CFD. The experiment and analysis were progressed in the same conditions. The results showed the quantitative difference under 30% between the numerical and the experimental pressure difference and mass flow rate.

• Journal of Bio-Environment Control
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• v.11 no.3
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• pp.101-107
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• 2002

This study was carried out to improve the performance of heat recovery device attached to exhaust gas flue connected to combustion chamber of greenhouse heating system. Three different units were prepared far the comparison of heat recovery performance; A-type is exactly the same with the typical one fabricated for previous study of analyzing heat recovery performance in greenhouse heating system, other two types (B-type and C-type) modified from the control unit are different in the aspects of airflow direction (U-turn airflow) and pipe arrangement. The results are summarized as follows ; 1. In the case of Type-A, when considering the initial cost and current electricity fee required for system operation, it was expected that one or two years at most would be enough to return the whole cost invested. 2. Type-B and Type-C, basically different with Type-A in the aspect of airflow pattern, are not sensitive to the change of blower capacity with higher than 25m$^3$.min$^{-1}$ . Therefore, heat recovery performance was not improved so significantly with the increment of blower capacity. This was assumed to be that air flow resistance in high air capacity reduced the heat exchange rate as well. Never the less, compared with control unit, resultant heat recovery rate of Type-B and Type-C was improved by about 5％ and 13％, respectively 3. Desirable blower capacity of these heat recovery units experimented were expected to be about 25m$^3$.min$^{-1}$ , and at the proper blower capacity, U-turn airflow units showed better heat recovery performance than control unit. But, without regard to the type of heat recovery unit, it was recommended that comprehensive consideration of system's physical factors such as pipe arrangement density, unit pipe length and pipe thickness, etc., was required for the optimization of heat recovery system in the aspects of not only energy conservation but economic system design.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.4
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• pp.237-242
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• 2009

In the pyroprocessing of spent nuclear fuels, fuel materials are recovered by electrochemical reactions on the surface of electrodes as well as stirring the electrolyte in electrolytic cells such as electrorefiner, electroreducer and electrowinner. The system with this equipment should first be scaled-up in order to commercialize the pyroprocessing. So in this study, the scale-up for those electrolytic cells was studied to design a large-scale system which can be employed in a commercial process in the future. Basically the dimensions of both electrolytic cells and electrodes should be enlarged on the basis of the geometrical similarity. Then the criterion of constant power input per unit volume, characterizing the fluid behavior in the cells, was introduced in this study and a calculation process based on trial-and-error methode was derived, which makes it possible to seek a proper speed of agitation in the electrolytic cells. Consequently examples of scale-up for an arbitrary small scale system were shown when the criterion of constant power input per unit volume and another criterion of constant impeller tip speed were respectively applied.