• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.881-892
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• 1999

Experiment was performed to study the characteristics of pressure drop of multi-channel tubes for automotive condenser using HFC-134a. Single phase liquid and two phase flow pressure drop were measured in one rectangular plain and three micro-fin tubes with 10 channels. Data are presented for the following range of variables: mass flux(200 to $600kg/m^2s$), and inlet saturation pressure of the refrigerant(1.0 and 1.6MPa). For subcooled flow, pressure drops are 10% and 12% higher than that predicted by the Petukhov equation with hydraulic diameter respectively. Two-phase flow pressure drop are compared with the previously proposed correlations, and well predicted by modified correlation that was derived from Traviss correlation. and correlated within -30~+20%. Also experimental data are correlated within -56%~+18% by Webb's prediction method based on the equivalent mass velocity concept originally proposed by Akers et al.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.751-754
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• 2004

There are many factors that affect on the flowing properties of high flowing concrete(HFC), which are fluidity, compactibility, non-segregation ability and fillingability. And because the aggregate which is one of the factors occupies high volume in concrete, it has a much effect on the properties of high flowing concrete according to its size, quality and quantity etc. This is an experimental study to analyze the effect of admixture and volume of coarse aggregate in concrete on the flowing properties of high flowing concrete. For this purpose, the kinds of admixture are fly-ash and blast furnace slag. Also volume of coarse aggregate in concrete are 280, 290, 300, 310, 320 $(\ell/m^3)$. The test of flowablity properties is slump-flow, Air content, V-lot, L-Flow. According to test results, it was found that the compactibility of HFC is more superior to use blast furnace slag than other, and according .to kind of admixture, most compatible volume of coarse are different. Also when used blast furnace slag, the volume of coarse are increased than used fly-ash.

• Journal of Korean Society of Disaster and Security
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• v.10 no.2
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• pp.35-41
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• 2017

Recently chemical intoxication related with the use of chemical extinguishing agents occurs frequently. With the industrialization, high-rising of building and increase of fire risk, we use the various extinguishing agents and the safe use become important. In this study I carried out the risk assessment of representative chemical extinguishing agents (HCFC-123, HFC-125) using the CHARM and got the meaningful qualitative outcome. This study is significant in that the risk assessment of chemicals was conducted using CHARM, chemical risk assessment tool. It is expected that the results will be utilized as the basic data for the national chemical safety management.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.7
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• pp.779-789
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• 2017

The effects of orally administered Seomaeyakssuk (Artemisia argyi H.) vinegar on lipid metabolism in Sprague-Dawley rats fed a high-fat and high-cholesterol (HFC) diet were analyzed. The experimental animals were divided into five groups: a normal diet group (normal, N), HFC diet group (control, C), HFC diet with lovastatin at 20 mg/kg body weight (B.W.) group (positive control, PC), HFC diet with malt vinegar group (TM), and HFC diet with Seomaeyaksuk vinegar group (TS) (2 mL/kg B.W.). After 4 weeks of feeding rats the experimental diet, contents of serum total lipids and total cholesterol levels of TM and TS groups were significantly lower than those of the PC group. Triglyceride contents of the TM and TS groups were not significantly different from those of the PC group but significantly lower than those of the C group. Content of serum high density lipoprotein-cholesterol was significantly lower than that of the N group but higher than that of the C group. Low density lipoprotein-cholesterol content of serum was 190.68 mg/dL in the TS group, which was the lowest except for the N group. Aspartate transaminase and albumin transaminase activities as a measurement of liver damage index were not significantly different between the TM, TS, and C groups. Serum thiobarbituric acid reactive substance content of the TS group was reduced to a similar level as the N group but was lower than that of the C group in the liver and significantly higher than that of the N group. Antioxidant activity of the TS group was 55.69% in serum, which was a similar to that of the N group, and was 52.39% in the liver, which was not significantly different than that of the C group. From these results, we conclude that Seomaeyakssuk vinegar improves serum lipid content as a result of the complex action of vinegar, an active ingredient of Seomaeyakssuk and a product of the fermentation process.

• Clean Technology
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• v.22 no.3
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• pp.154-160
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• 2016

For any conceivable desalination process using the gas hydrate formation, the kinetics has to be one of the most important parameters from the economic point of view. We thus were to improve the kinetics of the R-134a (also known as HFC-134a) gas hydrate formation by using promoters and three different kinds of edible surfactants were selected for the desalination process targeted to produce potable water; κ-carrageenan, lecithin, and polysorbate 80 among anionic, amphoteric, and nonionic surfactants, respectively. Then, the kinetics change of the R-134a hydrate formation was monitored by varying the surfactant concentration. Experimental results demonstrated that the rate of R-134a hydrate formation increases with the addition of edible surfactants in general and the effect as a promotor has an order of polysorbate 80 > κ-carrageenan > lecithin. As a supportive measure, the atomic charges of each surfactant were calculated by using a DFT (density functional theory)-based molecular modeling and the results showed a positive relationship between the promotor effect of each surfactant and the number of oxygens available for hydrogen bonding and the negativity of their atomic charge values.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1695-1699
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• 2004

The antioxidant enzymes, lipid peroxidation and free radicals assessment were made of the effects of selenium, copper and magnesium on bovine endemic fluorosis under high fluoride, low selenium and low copper productive conditions. Thirty-two beef cattle were selected from high fluoride area, and randomly divided into four groups with eight cattle each as follows: (1) high fluoride control group (HFC); (2) supplemented group with 0.25 mg/kg selenium (HFSe); (3) supplemented group with 15 mg/kg copper (HFCu) and (4) supplemented group with 0.25 mg/kg selenium+15 mg/kg copper+1 mg/kg magnesium (HFSeCuMg) per day for 83 days. Moreover, eight beef cattle were selected from non-high fluoride area as normal control group. Blood samples were collected from cattle on 0 d, 30 d and 83 d respectively, to analyze the enzyme activities and concentration of GSH-px, CAT, SOD, MDA and free radicals. The results showed that the contents of free radicals and MDA in HFC group were significantly higher, and the whole blood GSH-px, CAT, erythrocyte SOD activities were lower than the normal control group. Free radicals, metabolic imbalance and antioxidant disorder therefore, play an important role in fluorosis. However, GSH-px, CAT and SOD activities in HFSe group and HFSeCuMg group at 30 d and 83 d were markedly higher than the same groups at the 0 d and the HFC group at the same time. Likewise, there was a corresponding reduction in the contents of free radicals and MDA. These findings indicated that supplementation with selenium, copper and magnesium elevated high fluoride bovine antioxidant enzymes, and decreased MDA and free radicals contents. But, the activities of supplementation selenium group did not increase until day 83. These results demonstrated that fluorosis was associated with lower serum Se and Cu levels than in the control, and it was therefore concluded that fluorosis is associated with decreased serum levels of these minerals. Long-term high fluoride intake under productive condition enhances oxidative stress in the blood, thereby disturbing the antioxidant defense of cattle. Increased oxidative stress could be one of the mediating factors in the pathogenesis of toxic manifestations of fluoride. It is benefical for high fluoride cattle supplemented with proper selenium, copper and magnesium to increase fluoride excretion and obtain the protective impact of the activity of oxidative enzymes, and to decrease lipid peroxidation and free radicals contents.

• Journal of Nutrition and Health
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• v.38 no.10
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• pp.817-826
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• 2005

Recently it has been reported that vitamin A and retinol binding proteins (RBPs) in blood and urine were changed in the condition of diabetes mellitus or hyperlipidemia. Fruits and vegetables are recommended to consume for the people suffered from these chronic degenerative diseases. The main components of fruits and vegetables are dietary fibers, for example cellulose and pectin, of which function to affect the absorption and excretion of dietary fat and fat-soluble substances. This study was conducted to investigate the effect of dietary fibers on RBPs mRNA expression in liver, small intestine and serum of rat fed high fat diet during 4 weeks. Sprague-Dawley rats, weighing 121g on average, were divided into four groups; (Control; $17\%$ fat & cellulose supplement diet, HF0: $25\%$ fat & fiber free diet, B:.Uc: $25\%$ fat & cellulose supplement diet and HF0: $25\%$ fat & pectin supplement diet) . The rats fed high fat diet groups (HF0, HFC, HFP) tended to consume the food less than the control group, but FER of HF0 groups was significantly higher than the control (p < 0.05) . The weight of adrenal gland in high fat diet groups (HF0, HFC, HFP) was significantly less than the control. Total lipid in feces daily excreted and in liver did not show any significant differences among the groups. Total cholesterol in HFP group was significantly different from that of HFC group. Serum total cholesterol and triglyceride in other group tended to lower than other groups and HDL cholesterol higher. Consequently, AI (atherogenic index) was the lowest in HFP group. Vit A contents in feces daily excreted tended to lower in high fat diet groups (HF0, HFP) compared to the control group. That content in adrenal gland was the lowest in HF0 group, but not in liver. In HFP group were down-regulated cRBPI mRNA in liver and cRBPII mRNA in small intestine and up-regulated RBP and transthyretin expression in serum compared to the other groups. In conclusion, dietary fibers, especially pectin, in high fat diet might down-regulate the expression of CRBP I, CRBP II mRNA in liver and small intestine, but increase the secretion of RBP into serum and therefore inhance the bioavailability of Vit A through the body. (Korean J Nutrition 38(10): 817$\sim$826,2005)

• The Korean Journal of Food And Nutrition
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• v.33 no.6
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• pp.747-754
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• 2020

This study was conducted to evaluate the effect of high-oleate and normal-oleate peanut consumption on adipose mass and serum lipids in obese-induced C57BL/6J mice. After four weeks of the high-fat diet, mice were randomly divided into six groups: normal control (NC) diet, high-fat control (HFC) diet, high-oleate peanut-seed (HOPS) diet, normal-oleate peanut-seed (NOPS) diet, high-oleate peanut-oil (HOPO) diet, and olive-oil (OO) diet. After four weeks, all four experimental diet groups showed significantly lower body weight and epididymal fat weight than HFC group. In four experimental diet groups, serum triglycerides (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly lower, and high-density lipoprotein cholesterol (HDL-C) was significantly higher than HFC group. TG was significantly decreased in HOPS group (92.1±1.2 mg/dL) than NOPS group (101.7±5.3 mg/dL, p<0.05). Similarly, LDL-C was significantly lower in HOPS group (66.1±2.8 mg/dL) than NOPS (76.9±1.5 mg/dL, p<0.05), on the other hand, HDL-C indicated a significant elevation in HOPS (50.5±2.1 mg/dL) than NOPS group (45.2±1.6 mg/dL, p<0.05). This result suggests that the consumption of high-oleate peanut has a favorable effect on the plasma lipid profile.

• The Magazine of the IEIE
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• v.35 no.9
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• pp.58-69
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• 2008

디지털 케이블TV서비스는 헤드엔드(Head-End)센터로부터 QoS (Quality of Service)가 보장되는 케이블 HFC(Hybrid FiberCable)망을 통해 디지털 영상 방송이나 양방향서비스를 가입자 단말까지 제공하는 방송 통신 융합서비스이다. 본 고에서는 디지털 케이블TV 서비스를 제공하기 위한 디지털 케이블 네트워크 기술에 대해서 설명하고, 디지털 방송 및 양방향 서비스를 송출하는 방송센터시스템과 디지털 방송 기술에 대해 알아본 후 마지막으로 디지털 케이블TV의 향후 전망에 대해서 살펴보기로 한다.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.106.1-106.1
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• 2005