• Fire Science and Engineering
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• v.15 no.1
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• pp.34-40
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• 2001

Fire extinguishing efficiency of mixed gaseous agents were investigated by the cup-burner test and predicting by the model of flame extinguishing concentration. The binary mixed agents that tested were carbon dioxide/HFC-23, carbon dioxide/HCFC-22, carbon dioxide/HFC-227ea, carbon dioxide/HFC-125, carbon dioxide/FIC-13I1, Hexafluoropropylene/HFC-23 and ternary mixed agents were carbon dioxide/HFC-23/HFC-l34a, carbon dioxide/HFC-23/HFC-227ea, carbon dioxide/HFC-23/HFC-125. A model which contains the flame extinguishing concentration and composition of pure components predicted the flame extinguishing concentration of mixture well. This model was superior when each component of the mixture exhibit physical fire extinguishing performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.383-391
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• 2010

In this study, HFC152a, HFC134a/HFC152a and HC290/HFC134a/HFC152a mixtures are studied for the supplementary and alternative refrigerants for HFC134a used in automobile air-conditioners. Due to the high global warming potential of HFC134a, it has to be phased out in the long run. Thermodynamic performance of these refrigerants are measured in a bench tester of 3.5 kW capacity with an open type compressor under both summer and winter conditions. Test results show that the coefficient of performance (COP) and capacity of pure HFC152a and HFC134a/HFC152a mixture are 9.1~12% and 7% higher than those of HFC134a. As for the HC290/HFC134a/HFC152a, the COP is up to 9.5% higher than that of HFC134a with 1~2% of HC290 while that is up to 6.1% lower than that of HFC134a with 5% HC290. The capacity of the ternary mixture, however, is 8.6% higher than that of HFC134a at all compositions tested. The compressor discharge temperatures of all refrigerants tested are $6{\sim}10^{\circ}C$ higher than that of HFC134a. For all refrigerants, the amount of charge is reduced up to 32% due to the decrease in liquid density. Overall, these refrigerants provide good performance with reasonable energy savings with less environmental problem and thus can be used as long term alternatives for automobile air-conditioners.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1270-1278
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• 2010

Dietary effects of chicken treated with Hwangki-Beni Koji sauces (HBS) on serum and hepatic lipid profiles in rats fed high a fat and high cholesterol diet were investigated. Experimental plots (5 rats per each group) were divided into normal control diet group (NC), high fat and high cholesterol diet group (HFC), HFC plus 15% base sauce treated chicken supplemented diet group (HFC-BS), HFC plus 15% HBS-treated chicken supplemented diet group (HFC-HBS), and fed for 5 weeks. Feed intakes in HFC-HBS group were higher than those of HFC and HFC-BS groups, whereas body weight gain and feed efficiency ratio of the HFC-HBS group were lower than those of the HFC and HFC-BS groups. Serum alanine aminotransferase and aspartate aminotransferase activities of HFC-HBS group were significantly lower than those of HFC and HFC-BS groups. Level of serum triglyceride, total cholesterol and LDL-cholesterol in HFC-HBS group were 34.06%, 6.28% and 31.00% lower than those of HFC-BS group, respectively, whereas HDL-cholesterol level and atherogenic index in HFC-HBS group were 1.72-fold higher and 2.52-fold lower, respectively, than those of HFC-BS group. Level of hepatic total lipid, triglyceride and total cholesterol in HFC-HBS group were 9.53%, 5.25% and 22.20% lower than those of HFC-BS group, respectively. In the morphological results of liver, the hepatocytes of central vein lesion and intact hepatic cell plate are preserved well from steatosis in HFC-HBS group, whereas the hepatocytes in HFC and HFC-BS groups are distended by accumulation of multiple fat droplets, and sinusoids are occluded. In the above results, we expected that chicken treated with Hwangki-Beni Koji sauce may have functionalities of anti-obesity, anti-cholesterol and also, lowering anti-atherogenic index in high fat and high cholesterol diets.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.391-400
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• 2012

In this study, performance of HFC32/HFC152a mixture is measured in the composition range of 20 to 50% R32 with an interval of 10% for the comparison with the conventional HCFC22 in water-source heat pumps. Tests are carried out under the same capacity in a heat pump bench tester equipped with a variable speed compressor at the evaporation and condensation temperatures of 7/$45^{\circ}C$ and -7/$41^{\circ}C$ for summer and winter conditions, respectively. Test results show that the compressor power of the HFC32/HFC152a mixture is 13.7% lower than that of HCFC22 while the coefficient of performance(COP) the HFC32/HFC152a mixture is 15.8% higher than that of HCFC22. Hence, from the view point of energy efficiency, the HFC32/HFC152a mixture is excellent as compared to HCFC22. Compressor discharge temperatures of HFC32/HFC152a mixture are increased up to $15.4^{\circ}C$ as compared to that of HCFC22. The amount of charge for HFC32/HFC152 mixture decrease up to 27% as compared to that of HCFC22. Overall, HFC32/ HFC152a mixture is an excellent long term candidate to replace HCFC22 in water-source heat pumps.

• Information and Communications Magazine
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• v.15 no.7
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• pp.75-94
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• 1998

In this paper, HFC CATV networks are introduced. HFC CATV networks are currently considered as a most effective and plausible solution for subscriber access networks in the information superhighway, among others such as ADSL and B-WLL. The advantages of HFC CATV networks include its broad upstream and downstream channel bandwidths, much wider than PSTN's and its readiness. The HFC CATV networks are already well spread among the general subscribers in Korea. This fact will shorten the installation period and significantly reduce its cost. In addition, The structure and channel environment of the HFC CATV networks are introduced. At the same time, in this paper included are major problems in the HFC CATV networks and the solutions for these problems. Also discussed are data transmission, medium access control, IEEE802.14, and MCNS for standardizations. Moreover, additional telecommunications service activities in both Korea and other countries, using HFC CATV networks are also included. The topics which are covered in detail are the ones such as interoperation between HFC CATV networks and trunk line and the digital transmission performance test for the CATV networks. In the performance test, it is concluded that HFC CATV networks can satisfy the QoS for various additional services if the number of the subscribers in a cell is limited to less than 500 and other minor requirements are satisfied. Based on all these discussions and conclusions, HFC CATV networks are suggested in this paper for the subscriber access networks of the so called information superhighway.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.371-374
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• 2001

The upstream noise level was measured and analysed for the sample HFC networks to HFC subscriber capacity in the HFC network that is only for cable modem services. The upstream bands were measured not only in HFC networks that have accommodated only cable modem subscribers but in CATV networks that have accommodated cable modem and CATV subscribers. The study says that C/N of HFC networks be maintained though the networks have more cable modem subscribers than CATV networks do. This results are being expected to be used as a basis of network design and management of HFC network provider .

• Korean Journal of Clinical Laboratory Science
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• v.49 no.3
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• pp.263-270
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• 2017

This study was conducted to investigate the dietary supplementation of fruiting body of Hericium erinaceus (HE) mushroom on lipid profiles of serum and histological changes of the liver in rats with high fat and cholesterol diet. Five-week old female Sprague-Dawley albino rats were divided into three groups of 8 rats each: The normal control diet (NC group), high fat and cholesterol diet (HFC group), and HFC diet supplemented with 5% fruiting powder of Hericium erinaceus (HFC+HE group). In the HFC+HE group, serum total cholesterol, low density lipoprotein, and triglyceride concentrations were significantly reduced compared with the NC group. Body weight gain of those in the HFC+HE group were lower than those in the HFC group; whereas HFC+HE had no effect on the levels of plasma albumin, creatinine, blood urea nitrogen, uric acid, glucose, and total protein. The enzyme activities related to the liver function, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and, alkaline phosphatase (ALP), were lower in the NC group than in the HFC group, but without significance. Feeding the mushroom increased the excretion of total lipid and cholesterol. A histopathological analysis showed that the those in the HFC group developed hepatic steatosis, whereas those in the HFC+HE group developed small fat droplet. In conclusion, these results suggest that 5% HE supplementation to HFC diet provided health benefits by acting on lowering atherogenic lipid profile in rats with high fat and cholesterol diet.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.1-7
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• 2004

The physical properties of rigid polyurethane foam(PUF) synthesized using various types of blowing agents such as water, HFC-365mfc, HFC-245fa, HCFC-l4lb, CFC-11 and n-pentane were studied. The blending effect of blowing agents were also studied. The thermal conductivity, reaction rate, and cell morphology of the PUF with various blending ratio of blowing agents were investigated. The PUF blown by water shows the highest compressive strength among other single blowing agents. The thermal conductivity of PUFs blown by HFC-245fa and HFC-365mfc are close to that of PUFs blown by CFC-11. When HFC-365mfc was mixed with HFC-245fa(30mo1e$\%$) as coblowing agent, the mechanical property shows the highest value among other coblowing agents. It is that the thermal conductivity of PUFs depends on cell size of PUFs as well as thermal conductivity of blowing agent in gaseous form.

• Fire Science and Engineering
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• v.18 no.1
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• pp.7-12
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• 2004

For CFCs and Halons regulated by Montreal Protocol and their alternatives of HFC-23, HFC-125 HFC-227ea, HFC-236fa and the mixtures of inert gases of $Ar, N_2 and CO_2$, the thermodynamic properties of saturated pressure, density, enthalpy and viscosity were compared. In this study, the data from literature were expressed as a function of temperature. Thermodynamic properties of HFC compounds were similar to those of Halon-1301. Inert gas was mainly used as a mixture, but the physical properties of the inert gas does not have the favorable advantages over those of Halon-1301.

• Food Science and Preservation
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• v.18 no.2
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• pp.226-235
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• 2011

This study was conducted to investigate the cholesterol lowering effect and weight reduction of autoclaved soy flour, cheonggulgang and doenjang, which are fermented using Bacillus subtilis DJI, in rats fed a high-fat/high-cholesterol diet. Male Sprague-Dawley rats weighing 250 g, were divided into five groups; a normal diet group (N), a high-fat/high-cholesterol diet group (HFC), a high-fat/high-cholesterol diet with 5% autoclaved soy flour group (HFC-S), a high-fat/high-cholesterol diet with 5% cheonggulgang group (HFC-CJ), and a high-fat/high-cholesterol diet with 5% deonjang group (HFC-DJ). The body weight gain and adipose tissues weights increased in rats fed a high-fat/high-cholesterol diet, but decreased significantly in rats fed autoclaved soy flour, cheonggulgang and doenjang, compared with the HFC group. Food intake was lower in the all HFC groups (HFC, HFC-S.HFC-CJ and HFC-DJ) than that of the N group, However, there was no differences in the food intake between HFC diet groups. Serum triglyceride level increased with a high-fat/high-cholesterol dietgroup whereas HFC-CJ and HFC-DJ groups were markedly decreased serum triglyceride levels compared with N group. Levels of serum total cholesterol and LDL-cholesterol, and level of total cholesterol in the liver were significantly lower in the HFC-S group, the HFC-CJ group and the HFC-DJ group than that of the HFC group, but exerted no significant change between the HFC groups on levels of total lipid and triglyceride in the liver. Fecal total lipid content increased in the HFC-CJ group and the HFC-DJ group than those of the HFC group and HFC-S group. The activities of heparin-releasable lipoprotein lipase (HR-LPL) and total-extractable LPL in adipose tissues decreased in the HFC-S group, the HFC-CJ group and the HFC-DJ group compared with the HFC group. These results suggest that dietary cheonggulgang and doenjang may exert cholesterol-lowering effect and prevent obesity.