• Journal of the Korean Solar Energy Society
• /
• v.32 no.3
• /
• pp.114-122
• /
• 2012

Vertical closed-loop ground source heat pump systems(GSHP) have been installed widely in Korea since it can extract moderate temperature level of geothermal heat in a small area. As a ground heat exchanger, a vertical closed -loop type with brine circulation is mostly preferred since it is simple and less harmful to ground environment. However, it requires a secondary heat exchange loop between the refrigerant in a heat pump and the brine. By adding a geothermal heat exchanger in the secondary heat exchange loop, circulation pumps should be attached and the temperature difference between refrigerant and ground is increased, which are important parts of performance degradation. In this paper, annual and seasonal performances of direct expansion(DX) geothermal heat pump were estimated mathematically as an alternative of classical indirect geothermal heat pump based on the annual performance evaluation. As results, DX geothermal heat pump showed 43% higher annual performance than the classical U-tube geothermal heat pump.

• Applied Biological Chemistry
• /
• v.29 no.1
• /
• pp.83-89
• /
• 1986

To investigate effectors on the colloidal stability of whey and soybean proteins, characteristics of tofu-gel formation, effects of heat treatment and salt composition on the colloidal stability, and effects of heat treatment on storage stability were analyzed. When experimental tofus were made from the mixture of whey and soybean, the calcium in the whey precipitated the soy proteins, and disrupted the gel formation, which resulted in the curd of poor texture. In the heat treatment at $60{\sim}100^{\circ}C$, whey and the whey proteins dialyzed against distilled water were readily preciptated at over $70^{\circ}C$, but the mixture of whey and soy extract as well as soy extract were stable at the range of temperature. The proteins of soy extract, whey dialyzed against sodium phosphate buffer, and the mixture were stable at the same heat treatment, and this suggested that phosphates in the soy extract stabilize specialty the whey proteins. Soy proteins were easily destabilized by adding $CaCl_2(0.05{\sim}0.07M)$ at $80{\circ}C$ and $70{\sim}85%$ of the proteins in soy extract and the mixture were preciptated, while only $30{\sim}55%$ of the proteins in whey dialyzed against distilled water were destabilized at the same conditions. Storage stability at $4^{\circ}C$ of the mixture was increased when the mixture was treated at $63^{\circ}C$ and lower temperature.

• Journal of the Korean Society of Food Culture
• /
• v.30 no.3
• /
• pp.370-376
• /
• 2015

In this study, we compared the organoleptic and other qualities of fermented milk containing 10 or 15% purple carrot extract that had either been previously fermented with Aspergillus oryzae or not fermented. Fermentation characteristics, pH, chromaticity, viscosity, viable cell counts, and sensory evaluations were measured. The pH and acid values did not differ between purple carrot extract fermented with Aspergillus oryzae and non-fermented extract. Viable cell counts were significantly higher in 15% purple carrot extract fermented with Aspergillus oryzae compared to the control after fermentation. Regarding characteristic changes, purple carrot extract fermented with Aspergillus oryzae group showed a lower red value but higher yellow value compared with non-fermented purple carrot extract due to heat-sterilization. Both fermented and non-fermented extract groups showed significantly increased viscosity compared to control. In the sensory evaluation, 15% purple carrot extract fermented with Aspergillus oryzae showed the highest score. In conclusion, addition of 15% purple carrot extract fermented with Aspergillus oryzae resulted in a superior fermented milk product.

• Journal of Animal Science and Technology
• /
• v.58 no.11
• /
• pp.39.1-39.12
• /
• 2016

Background: The current study investigates the anti-stress effects of clove (Eugenia caryophyllus) extracts (0, 200, 400, and 600 mg/kg) on serum antioxidant biomarkers, immune response, immunological organ growth index, and expression levels of acute phase proteins (APPs); ovotransferrin (OVT), ceruloplasmin (CP), ceruloplasmin (AGP), C-reactive protein (CRP), and serum amyloid-A (SAA) mRNA in the immunological organs of 63-d-old male black-meated Silkie fowls subjected to 21 d chronic heat stress at $35{\pm}2^{\circ}C$. Results: The results demonstrated that clove extract supplementation in the diet of Silkie fowls subjected to elevated temperature (ET) improve growth performance, immune responses, and suppressed the activities of glutathion peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and thioredoxin reductase (TXNRD); reduced serum malonaldehyde (MDA) and glutathione (GSH) concentrations when compared with fowls raised under thermoneutral condition (TC). Upon chronic heat stress and supplementation of clove extracts, the Silkie fowls showed a linear increase in GSH-Px, SOD, CAT, and TXNRD activities (P = 0.01) compared with fowls fed diets without clove extract. ET decreased (P < 0.05) the growth index of the liver, spleen, bursa of Fabricius and thymus. However, the growth index of the liver, spleen, bursa of Fabricius and thymus increased significantly (P < 0.05) which corresponded to an increase in clove supplemented levels. The expression of OVT, CP, AGP, CRP, and SAA mRNA in the liver, spleen, bursa of Fabricius and thymus were elevated (P < 0.01) by ET compared with those maintained at TC. Nevertheless, clove mitigates heat stress-induced overexpression of OVT, CP, AGP, CRP and SAA mRNA in the immune organs of fowls fed 400 mg clove/kg compared to other groups. Conclusions: The results showed that clove extracts supplementation decreased oxidative stress in the heat-stressed black-meated fowls by alleviating negative effects of heat stress via improvement in growth performance, antioxidant defense mechanisms, immunity, and regulate the expression of acute phase genes in the liver and immunological organs.

• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.965-969
• /
• 2006

This study investigated heat transfer characteristics between absorber and heat pipe used to extract heat from concentric evacuated tubular collectors. In order to experiment, T-type thermocouples are attached to a evaporator of heat pipe and absorber of inner tube. A wall temperature distribution of absorber and heat pipe were carried out by experimental method under actual various ir-radiance and outdoor conditions. As a result, As to increase an irradiance, a wall temperature of absorber and heat pipe is gradually increased. The heat pipe was required about 20min to obtain steady state operation after start up and operates stable during various irradiance conditions. And the collector efficiency was about $50{\sim}70%$ when a mass flow rate is about $1.3{\ell}/min$.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.1
• /
• pp.100-106
• /
• 1999

Use of chemical preservative for controlling harmful microorganisms in food products has been debated due to public concerns about food quality because of perceived toxic and carcinogenic potential. Thus, use of non toxic natural antimicrobial agents has become essential. This study was investigated to determine the antimicrobial activity of water or ethanol extract of commercially available tea, and of solvent fractionated ethanol extracts obtained from steamed green tea. Both of water and ethanol extracts of green tea(steamed or roasted), oolong tea and black tea exhibited strong antimicrobial activity against gram positive and negative bacteria, but not effective against yeast and mold. Also, antimicrobial activity of ethanol extract of 4 different kinds of tea was stronger than that of water extract. Among 4 different tea, ethanol extract of steamed green tea was further fractionated. One thousand g/disk buthanol extract had the strongest antimicrobial activity against bacteria and mold. The concentration of the antimicrobial activity of buthanol extract in tested microorganisms ranged from 125~1000 g/disk except for Rhizopus javanicus. Antimicrobial activity of buthanol extract of steamed green tea was not destroyed by heating at 100oC for 60 min and at 121oC for 15 min, which is very stable over heat treatment. The inhibitory effect of the buthanol extract on the growth of Listeria monocytogenes and Staphylococcus aureus was investigated. Growth of both strains was started in the presence of 250 and 500 g/ml after 12 and 24 hour respectively, whereas complete inactivation of both strains was occurred in the presence of 1000 g/ml.

• Korean Journal of Pharmacognosy
• /
• v.52 no.1
• /
• pp.49-54
• /
• 2021

As the consumption of avocado fruits and avocado oils is steadily increasing, the amount of avocado seeds which are thrown away as by-products is also inceasing. Thus, the possibility of use of avocado seeds as natural preservatives was studied focused on the antioxidant effect. The extraction of avocado seeds and seed husks with 100% ethanol by maceration showed highest antioxidant activities and lowest IC50 values compared to 80% ethanol extract. Furthermore, 100% ethanol extract of avocado seeds and seed husks included significantly higher amount of polyphenols than 80% extract. However, total flavonoid content of 100% avocado seed extract was not signigicantly different from 80% seed extract, whereas that of 100% avocado seed husk extract was significantly higher than 80% seed husk extract. In case of acid values, heating of oil alone for 120 and 180 min significantly increased the acid values, whereas the treatment of oil with seed and seed husk extract signficantly decreased the acid values. These results suggest that antioxidant effects of avocado seeds and seed husks protected the oil against heat-induced acidification. Thus, avocado seeds and seed husks have a potential to be developed as an natural antioxidant and natural preservative which could be used commercially.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.5
• /
• pp.384-390
• /
• 2006

To improve the extractability of carnosine and the levels of pro-oxidants such as iron in eel (Anguilla japonica) extracts, we examined the effects of extraction time, temperature, ion exchange chromatography and ultrafiltration (UF). The respective protein and total iron were reduced approximately 55 and 60% at 60$^{\circ}C$, 63 and 70% at 80$^{\circ}C$, 68 and 76% at 100$^{\circ}C$ and 82 and 48% with ion exchange chromatography, respectively, compared to the untreated extract. However, there was no significant difference in the carnosine levels in the eel extracts. Ultrafiltration reduced the protein content of the extract by 52% compared with the untreated extract. UF reduced the protein contents of the samples from 60, 80, and 100% heat treatment and ion exchange chromatography treatment by 27, 50, 46 and 47%, respectively. UF reduced the total iron contents of the identical four treatments by 14, 22, 23, and 43%, respectively, while UF increased the carnosine by 23, 17, 20, and 6%, respectively.

• Journal of Ginseng Research
• /
• v.35 no.1
• /
• pp.39-44
• /
• 2011

We studied the acute oral toxicity of black ginseng (BG) produced by heat process in rats. Single acute BG extract doses of 0, 5, 10, and 15 g/kg dissolved in saline were administered by oral gavage and the animals were kept under observation for 14 days. The single administration of BG extract up to 15 g/kg did not produce mortality, behavioral change or abnormal clinical signs in the rats. These results indicated that the oral $LD_{50}$ of the BG extract in the rats is higher than 15 g/kg. Compared to the control group, no treatment-related biologically significant effects of BG extract were noted in the measurements of the body weight or food intake. At the end of the period, the biochemical parameters and hematological parameters were analyzed in the plasma and blood. A histopathological examination of the liver and kidney was also conducted. Only the blood nitrogen urea and potassium levels in the biochemical indices showed significant differences at 10 and 15 g/kg doses of BG extract compared to the control group. These changes were not considered to be due to the toxicity. None of the other clinical chemistry parameters were affected. Therefore, these results indicate that the BG by heat processing is virtually nontoxic.

• Solar Energy
• /
• v.8 no.1
• /
• pp.5-12
• /
• 1988

One of the effective means to transfer the heat into and from the energy storage medium is thermosyphon. In this study, a two-phase closed thermosyphon with circular fins was used to extract the thermal energy stored in paraffin wax (Sunoco p-116). Heat transfer characteristics along the heat flow path were investigated as well as the overall performance. Some of the important results are as follows: (1) The temperature distribution of the wax in the radial direction was always maintained fairly uniformly; (2) Compared with bare thermosyphon, the heat transfer rate was vastly improved in the early stage of the experiment; and (3) Heat transfer coefficient between the wax and evaporating section of thermosyphon remained nearly constant during the experiment.