• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.305-309
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• 2008

This paper presents an innovative prototype of a new conceptual electromagnetic induction eddy current based fluid heating appliance using voltage-fed quasi resonant zero voltage soft switching PWM high-frequency inverter using IGBTs, which can operate at a constant frequency variable power regulation scheme. The promising simple high efficient low noise inverter type electromagnetic induction eddy current based pipeline fluid heating appliance is proposed for saturated steam generator, superheated steam generator, hot water and hot air producer, metal catalyst heating for exhaust gas cleaning in engine. Under these technological backgrounds, a novel electromagnetic induction eddy current Dual Packs Heater(DPH) based pipeline fluid heating incorporates thin metal layer type package for continuous fluid heating appliances applying two types of voltage-fed quasi load resonant ZVS-PWM high frequency inverter. The unique features of a novel electromagnetic induction eddy current DPH based continuous pipeline fluid heating appliance is illustrated on the basis of simulation and discussed for the steady state operating characteristics and experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.453-457
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• 2016

In various industrial plants such as power generation plants, petrochemical plants, and unit factories, there is an increasing demand for a system that generates hot water using waste or surplus steam. Compact steam unit (CSU), which produces hot water by using steam, is a good solution considering energy reuse. In this study, as a basic study to develop a high-pressure CSU, heat transfer characteristics of a hybrid heat exchanger were investigated through experiments, in order to use the hybrid heat exchanger instead of a conventional plate heat exchanger as the core component of CSU. The experimental results are the followings. Heat balance between the hot side and cold side was satisfied within ${\pm}5%$. Overall heat transfer coefficient increased linearly as the Reynolds number increased and exceeded $5,524W/m^2K$ when the flow velocity was above 0.5 m/s. In addition, pressure drop also increased as the Reynolds number increased, and pressure drop per unit length was below 50 kPa/m.

• The Korean Journal of Food And Nutrition
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• v.34 no.3
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• pp.295-301
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• 2021

Steaming is a method that has traditionally been used for medicinal plant extraction. This study investigated nitrite oxide production, ferrous ion chelating activity, α-glucosidase, xanthine oxidase, and acetylcholinesterase inhibitory activities of ethanol, acetone and hot-water extracts of Codonopsis lanceolata prepared by steaming seven times. MTT assay showed that each extract was non-toxic up to a concentration of 700 ㎍/mL confirming that there was no cytotoxicity in all extracts. The α-glucosidase, xanthine oxidase, and acetylcholinesterase inhibitory activities exhibited by the hot-water extract obtained from steaming seven times were higher (83.1%) than the other extracts. Higher production of nitrite oxide and better ferrous chelating activity was recorded with hot-water extract compared to ethanol and acetone extracts. These results indicated that more steaming of Codonopsis lanceolata extracts would be required to validate the possibility of developing antioxidants. Also, further study is needed to determine if the components present in the tested extracts might be useful in the prevention of Alzheimer's disease. These results showed that hot-water extracts may be useful for their antioxidant and the production inhibitory activity of nitrite oxide. It will be helpful in the investigation of the constituent analysis of the steam-processed product of Codonopsis lanceolata.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.7-14
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• 2017

This study carried out a numerical analysis of the effects of hot waste water supply on the performance of a Type II absorption heat pump. There are two types of hot waste water supply, regular series flow and reverse series flow. Also it investigated the interaction between each type of flow and heat exchange solutions. As the effectiveness of heat exchange solutions increase, the steam generation and (COP) increase as well. If the effectiveness of a heat exchange solution is lower than 0.566, the steam generation rate of the reverse flow is lower than that of the regular series flow. A high effectiveness of heat exchange solution is therefore required to make a larger amount of steam in reverse series flow than with ordinary series flow. The COP difference between the two types of flow decreases with the increasing effectiveness of the heat exchange solution. Thus, a reverse flow type absorption heat pump can match the high steam generation rate and COP of the ordinary flow type when a highly effective heat exchange solution is applied.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.626-632
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• 2004

Of hot- water extracts prepared from 30 kinds of herbal medicines, Acanthopanax senticosus (75.6% inhibition of control), Atractylodes macrocephale (71.3%), Panax ginseng (70.0%), Glycyrrhiza uralensis (66.3%) and Angelica acutiloba (63.1%) showed the potent tumor metastasis inhibition activity against colon 26-M3.1 lung carcinoma at 2.5 mg/kg body weight, whereas the other extracts had a little activity, except for Pueraria thunbergiana (58.6%) and C. leticulata (54.9%) having the intermediate activity. We also found that Citrus leticulata (1.80-fold of control), A. macrocephale (1.73-fold), A. senticosus and G. uralensis (1.64-fold) enhanced on Peyer's patch cells mediated-hematopoietic response at 100 $\mu\textrm{g}$/mL. In addition, these active herbal medicines were prepared into steam distillates to improve the food rheology as beverage, and to remove the inactive components. Among these steam distillates, A. macrocephale, G. uralensis and A. senticosus showed the significant tumor metastasis inhibition activity at 2.5 mg/kg body weight (58.7%, 50.3% and 41.9%, respectively), and A. macrocephale had the potent activity even at 0,25 mg/kg body weight (49.7%). In treatments of steam distillates with Peyer's patch cells, A. macrocephale and A. senticosus significantly increased the bone marrow cell proliferation even at 10 $\mu\textrm{g}$/mL (1.49- and 1.28-fold of control). Although steam distillates had lower activity than hot-water extracts, herbal medicines, such as A. macrocephale and A. senticosus, showed the high immunostimulating activity in hot-water extracts as well as steam distillates. Therefore, these results assumed the possibility that steam distillates from herbal medicines might be utilized to food industry for beverage.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.4 no.2
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• pp.1-6
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.29-42
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• 2016

This study analyzes the economic efficiency of utilizing hot waste water at a thermoelectric power plant, which is part of recent projects supported by the Korean government to foster new energy industry. The author proposes an institution that provides economic incentives to promote the project. Based on a method of calculating Levelized cost of energy (LCOE), this study finds that the LCOE of using hot waste water at power plants is higher than that of oil boiler, biomass and a power plant's auxiliary steam but similar to that of the geothermal system. Also, according to sensitivity analysis on the LCOE of each element in the system of using hot waste water, a distance of heat supply is most sensitive. Therefore, this study shows that when the government devises an incentive-based institution to expand the project of utilizing hot waste water, it is necessary to establish Renewable Energy Certificate (REC) weights that are differentiated by a distance of heat supply.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.91-98
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• 2013

In this study, we have carried out development and performance evaluation of optimized MEMS(Multi-Effect-Multi-Stage) fresh water generator with $7m^2/day$ for solar thermal desalination system. The developed MEMS was composed of high temperature part and low temperature part. This arrangement has the advantage of increasing the availability of solar thermal energy. The MEMS consists of 2 steam generators, 5 evaporators, and 1 condenser. Tubes of heat exchanger used for steam generators, evaporators and condenser were manufactured by corrugated tubes. The performance of the MEMS was tested through in-door experiments, using an electric heater as heat source. The experimental conditions for each parameters were $20^{\circ}C$ for sea water inlet temperature to condenser, $8.16m^2$ /hour sea water inlet volume flow rate, $70^{\circ}C$ for hot water inlet temperature to generator of high temperature part, 3.6 4.8, 6.0 $m^2/hour$ for hot water inlet volume flow rate. As a result, The developed MEMS was required about 85 kW heating source to produce $7m^2/day$ of fresh water. It was analyzed that the performance ratio of MEMS was about 2.6.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1283-1287
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• 2009

In this study, an analysis was performed on an evaporative steam generator (concentrator), where natural circulation convective boiling occurs on tube-side by condensing hot steam on shell-side. Existing correlations on two-phase pressure drop, boiling or condensation heat transfer were used for the analysis. The effect of number of tubes, tube length, etc. on thermal performance was investigated. Simulation results reveal that steam generation rate increases almost proportionally to the tube length, or number of tubes. It is also shown that water circulation rate decreases as tube length increases.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.339-343
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• 2018

Effects of different drying processes, such as hot air drying (HA), superheated steam with hot air drying (SHS/HA), and superheated steam with far infrared radiation (SHS/FIR), on the properties of cherry tomatoes (Solanum lycopersicum var. cerasiforme) were studied. Characteristics of dried cherry tomatoes were determined by examining the water content, internal microstructure, and rehydration capacity under different drying processes. Moreover, ascorbic acid (AA) and lycopene levels were also measured to evaluate thermal damage caused by drying. Cherry tomatoes dried using both SHS/HA and SHS/FIR had water content and water activity similar to those of intermediate moisture food, indicating partial dehydration after combined drying processes. Although AA and lycopene levels decreased drastically after drying, tomatoes dried using SHS/FIR showed the lowest losses of AA and lycopene among samples. Cherry tomatoes dried using SHS/FIR showed a less compact internal cell structure than that of cherry tomatoes dried using HA and SHS/HA, resulting in the highest rehydration capacity. These results suggest that a combined drying process such as SHS/FIR is more effective than conventional hot air drying for the production of partially dried cherry tomatoes with improved quality attributes.