• Journal of the Korean Society for Heat Treatment
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• v.26 no.1
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• pp.14-20
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• 2013

Duplex stainless steel, which is a kind of stainless steel with a mixed microstructure of about equal proportions of austenite and ferrite, is generally known as a unique material with excellent corrosion resistance and high strength. However, toughness, strength, and corrosion resistance of the steel could be reduced due to precipitation of topologically closed packed phases such as sigma phase during cooling. In case of large forged products, they have strong possibility that ${\sigma}$-phase precipitates due to difference of cooling rate between surface and inner of the products. Investigation on sigma phase precipitation behavior of duplex stainless steel with change of cooling rate was carried out in this study. Forged SAF 2205 duplex stainless steel was used as specimens to examine the cooling rate effect. Dissolution behavior of sigma phase was also discussed through resolution test of duplex stainless steel containing lots of sigma phase. Experimental results revealed that impact energy was very sensitive to precipitation of small amount sigma phase. However, sigma phase could be removed by short term resolution treatment and impact resistance of the duplex stainless steel was restored.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.83-87
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• 2000

To investigate the effect of growth regulators and antioxidant in anther floating cultures of rice, anthers were cultured in liquid media supplemented with different growth regulators, and the effect of antioxidant mixture : (Sigma Chemical Co.) on callus induction and plant regeneration were investigated. N6 medium with 1 mg/L 2,4-D and 1 mg/L kinetin was the best for rice anther floating cultures, which showed 48.5% of callus induction and 6.8% of green plant regeneration. The callus induction was not affected by antioxidant mixture in liquid medium, and antioxidant mixture (250 mg/L) was effective for the reduction of brownish callus and improvement of plant regeneration Antioxidant mixture showed better effectiveness when it was supplemented to both media for callus induction and plant regeneration.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.335-338
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• 2006

The more deeply the researches make progress in ocean researches including the seabed resource investigation or the oceanic ecosystem investigation, the more important the role of UUV gets. In case of study on the deep sea, there are difficulties in telecommunications between AUV and ships, and in data communication and recharging. Therefore, docking is required. In AUV docking system, the AUV should identify the position of docking and make contact with a certain point of docking device. MOERI (Maritime & Ocean Engineering Research Institute), KORDI has conducted the docking testing on AUV ISIMI in KORDI Ocean Engineering Water Tank. As AUV ISIMI approachs the docking device, it is presented that attitude is unstable, because the lights Which is on Image Frame are disappeared. So we fix the rudder and stem, if the lights on Image Frame are reaching the specific area in the Image Frame. In this paper, we intend to solve the problems that were found in the testing, which, first, will be identified via simulation.

• The Korea Journal of Herbology
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• v.30 no.1
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• pp.1-9
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• 2015

Objectives : The present study was designed to investigate the anti-diabetic effects of Mori Folium (Morus alba L. of Moraceae) extract (MFE) on high fat diet (HFD) and streptozotocin (STZ)-induced type II diabetes mellitus in mice. Methods : The mice (C57BL/6J) were fed HFD for 8 weeks and then was induced with a single injection of STZ (75 mg/kg). The diabetic mice were divided into four groups [(STD, HFD, HFD + MFE and HFD + quercetin (QUR)] and administered with MFE or OUR for 4 weeks. Fasting blood glucose, lipid profile (triglycerides and cholesterol etc.), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), insulin and leptin were measured every 2 weeks. Results : Body weight gain was lower in the MFE and QUR groups than HFD group. The fasting blood glucose was lower in the MFE and QUR groups. Oral glucose and insulin tolerance were decreased in the MFE and QUR groups. The levels of serum total cholesterol, triglycerides, and LDL cholesterol were reduced in the MFE and QUR groups. The HDL cholesterol was much higher in the MFE and QUR groups than HFD group. The levels of GOT, GPT and atherogenic index were decreased in the MFE and QUR groups. The serum insulin and leptin concentrations were reduced in the MFE and QUR groups. Conclusions : These results showed that MFE could decrease blood glucose level and lead to an amelioration in dyslipidemia states on HFD/STZ-induced type II diabetes mellitus in mice.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.579-589
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• 1985

The storage tank of the natural-circulation-solar-hot-water system equipped with flat-plate solar collectors is located at higher elevation than the solar collectors. Therefore, the heat loss from the system due to a reversed flow during the night-time is an important factor as well as the day-time thermal performance of the system. The thermal performance of the natural-circulation-solar-hot-water system with flat-plate solar collectors during the day-time depends mainly on the heat collecting efficiency of the solar collectors, whereas its thermal performance during the night-time depends on the system configuration , such as the elevation of the water storage tank with respect to the solar collectors and the piping connections between the storage tank and the solar collectors, as well as thermo-physical properties of the circulating fluid. In the present work, a computer program has been developed to simulate a typical natural-circulation-solar-hot-water-system, and a series of simulation tests have been carried out with the computer program to examine the thermal performance of the system during the day-time as well as the hight-time. In addition , a series of experiment have been conducted under a real sun condition using a natural-circulation-solar-hot-water-system constructed and installed at the KAIST building to compare with the results obtained from computer simulations.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.463-469
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• 2018

A currently used roof green system with multi layers has a low constructability. Therefore a new integrated waterproof & root barrier sheet and roof green box unit system was developed using steel plate fixture and cone type fixture by electromagnetic induction heating method. This study was proceeded to evaluate adhesion performance of two types of fixtures on Engineering PE, TPO, PVC sheet in a normal condition, repeated heating and cooling condition. As a result, adhesion load on Engineering PE sheet showed the highest value. The adhesion loads of steel plate fixture showed higher value as heating temperature was getting higher. However adhesion loads of cone type fixture showed opposite tendency. Regarding to the test conditions, test results of normal condition, repeated heating and cooling condition showed same value. The cone type fixture using butyl tape showed 7 times lower adhesion load than that of cone type fixture using electromagnetic heating and 28% lower adhesion load in a repeated heating and cooling condition than a usual condition.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.449-452
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• 2002

A filamentous microorganism was isolated from completely rotten wood for the production of cellulolytic enzyme. The Trichoderma sp. FJ1 produced a large amount of cellulolytic enzymes, such as CMC, xylanase, ${\beta}-glucosidase$, and avicelase. For the production of the enzymes, when cellulolsic wastes were used as carbon sources of strain FJ1, rice straw showed higher enzyme activities than sawdust and pulp. The activities of CMC, xylanase, ${\beta}-glucosidase$, and avicelase were 2.95, 5.89, 0.45, and 0.12 U/ml in use of rice straw, respectively. To enhance production of the enzymes, the mixture substrate of rice straw and commercial cellulosic materials was investigated as carbon sources. The highest activities of CMCase, ${\beta}-glucosidase$, and avicelase were found in the mixture of rice straw and avicel, particularly rice straw:avicel (50:50), and the highest xylanase was obtained in the mixture ratio of 71:29. Bacto peptone addition of 0.1% showed enhanced production of the cellulolytic enzymes in which the activities of CMCase, xylanase ${\beta}-glucosidase$, and avicelase were 19.23, 27.18, 1.28, and 0.53 U/ml, respectively. The production of the enzymes using rice straw was efficiently induced in present of avicel and pulp containing high content of cellulose. Consequently, the filamentous microorganism, strain FJ1 utilized various cellulosic wastes as carbon sources and cellulases productivities were excellent compared to those of others strains reported previously, suggesting that the strain FJ1 will be expected as a favorable candidate for biological saccharification of cellulosic wastes in further.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.561-566
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• 2017

Butt-fusion welding process is used to join the polymeric pipes. Recently, some researchers suggest the curved surface to enhance a welding quality. We investigated how curved welding surface affects heat and flow behaviors of polymer melt during the process in 2D axisymmetric domain with finite element method, and discussed the effect to the welding quality. In this study, we considered HDPE pipes. In heat soak stage, curved phase interface between the melt and solid is shown along the shape of welding surface. In jointing stage, squeezing flow is generated between curved welding surface and phase interface. The low shear rate in fusion domain reduces the alignment of polymer to the perpendicular direction of pipes, and then this phenomenon is expected to help to enhance the welding quality.

• Herbal Formula Science
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• v.16 no.2
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• pp.183-191
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• 2008

Acetaminophen (N-acety1-p-aminophenol, paracetamol) is widely used as an over-the-counter analgesic and antipyretic drug. Intake of a over dose of acetaminophen may result in severe hepatic necrosis. In this study, we investigated the liver damage in mice using single dose (300 mg/kg) of acetaminophen and the possible protective effects of administration (50-200 mg/kg body weight) of SB-Ex on acetaminophen-induced liver damage in mice. The alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activities were determined in the plasma of mice. The effect of SB-Ex on lipid peroxidation product thiobarbituric reacting substances (TBARS) and some antioxidant enzymes superoxide dismutase (SOD), catalase, d-aminolevulinate dehydratase (${\sigma}$-ALA-D) activities, and gluthathione peroxidase (GPx), were also evaluated in the mouse liver homogenate. Acetaminophen caused liver damage as evident by statistically significant increased in plasma activities of AST and ALT. There were general statistically significant losses in the activities of SOD, catalase, ${\sigma}$-ALA-D, and GPx and an increase in TBARS in the liver of acetaminophen-treated group compared with the control group. However, SB-Ex was able to counteract these effects. These results suggest that SB-Ex can act as hepatoprotectives against acetaminophen toxicity and is a good candidate for further evaluation as an effective chemotherapeutic agent.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.179-185
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• 2014

Average temperature and temperature uniformity in a battery cell are the important criteria of the thermal management of the battery pack for hybrid electric vehicles and electric vehicles (HEVs and EVs) because high power with large size cell is used for the battery pack. Thus, liquid cooling system is generally applied for the HEV/EV battery pack. The liquid cooling system is made of multiple cooling plates with coolant flow paths. The cooling plates are inserted between the battery cells to reject the heat from batteries to coolant. In this study, the cooling plate with U-shaped coolant flow paths is considered to evaluate the effects of coolant flow condition on the cooling performance of the system. The counter flow and parallel flow set up is compared and the effect of flow rate is evaluated using CFD tool (FLUENT). The number of counter-flows and flow rate are changed and the effect on the cooling performance including average temperature, differential temperature, and standard deviation of temperature are investigated. The results show that the parallel flow has better cooling performance compared with counter flow and it is also found that the coolant flow rate should be chosen with the consideration of trade-off between the cooling performance and pressure drop.