• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.110-119
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• 2009

A fire should be accompanied by the heat and smoke. However, smoke is considered main cause of heavy casualties. Smoke easily spreads away from the fire area to remote space and cause mortal wound for the resident. A technical way effectively protecting the life and property from the smoke is the smoke control system of the building. Pressurized air supply system can be considered to prevent the refuge area from the smoke infiltration that evacuate residents via evacuation route for life safety. This paper is related with performance estimation and the effectiveness of the pressurized air supply system through experiments.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.71-78
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• 2012

Rainfall infiltration test under one dimensional condition is conducted to evaluate the effect of rainfall intensity on seepage velocity and infiltration characteristics for initial unsaturated sediment. Experimental results are compared with those numerical simulations with respect to variations of pore water pressure, degree of saturation and discharge velocity with time, and both results give good agreement. High rainfall intensity tends to increase seepage velocity almost linearly. But it shows rapid increase as rainfall intensity approaches saturated hydraulic conductivity of the sediment. In addition, the upper part of wetting front depth is partially saturated, not fully. Therefore, actual wetting front depth is considered to advance faster than theoretical prediction, which leads to slope instability of unsaturated slope due to surface rainfall.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3C
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• pp.113-120
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• 2012

An actual slope failure was analyzed in residual soils at Jinju. Due to rainfall infiltration, the safety factor decreases in the unsaturated layers, since the effective stress and shear strength decrease. In this study, the effective stress is based on suction stress using soil water retention curve. Unsaturated properties were evaluated on soil water retention curve, hydraulic conductivity and shear strength with samples from the site. After infiltration analysis of unsaturated flow under the actual rainfall, the distribution of pore water pressure could be calculated in the slope layers. In the stress field of finite elements, an elastic analysis calculated total stress distribution in the layers and also shear stresses on the slip surface using elastic model. On the slip surface, suction stress and effective stress evaluated the shear strength. As a result, the factor of safety was calculated due to rainfall, which could simulate the actual slope failure. In particular, it was found that the suction stress increases and both the effective stress and the shear strength decrease simultaneously on the slip surface.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.696-702
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• 2017

Metabolic syndrome, including obesity, glucose intolerance and elevated blood pressure, is related to type 2 diabetes and cardiovascular disease. Previous studies have reported the anti-oxidative, anti-inflammatory and anti-diabetic effects of purple corn extract. We investigated the efficacy of purple corn extract (PC) against high-fat diet (HFD)-induced obesity and glucose intolerance, and examined the underlying mechanisms by analyzing expression of proteins and genes involved in glucose regulation and macrophage infiltration. C57BL/6 mice were fed with normal chow diet (ND), or HFD treated with distilled water (DW, control) or PC, for 10 weeks. Although body weights were similar in the HFD-fed groups, we observed a decrease in the liver and epididymal adipose tissue (EAT) weights, and enhanced glucose tolerance test (GTT) results in the PC group, as compared with DW group. Liver showed increased Akt phosphorylation in the PC-treated mice; however, no changes were observed in the EAT, for all groups. In PC-treated mice, decreased macrophage infiltration was seen in the EAT, with a reduced expression of macrophage marker genes. Finally, proinflammatory cytokine gene expressions were decreased by PC in the EAT, and a modest trend for downregulation was observed in the liver. Hence, we conclude that PC may decrease glucose intolerance by increasing the phosphorylation of Akt and reducing the macrophage infiltration into the EAT.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.23-32
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• 2015

This paper addresses the effects of extreme rainfall on the stability of cut slopes in Yen Bai city, Northern Viet Nam. In this area, natural slopes are excavated to create places for infrastructures and buildings. Cut slopes are usually made without proper site investigations; the design is mostly based on experience. In recent years, many slope failures have occurred along these cuts especially in rainy seasons, resulting in properties damaged and loss of lives. To explain the reason that slope failure often happens during rainy seasons, this research analyzed the influence of extreme rainfalls, initial ground conditions, and soil permeability on the changes of pore water pressure within the typical slope, thereafter determining the impact of these changes on the slope stability factor of safety. The extreme rainfalls were selected based on all of the rainfalls triggering landslide events that have occurred over the period from 1960 to 2009. The factor of safety (FS) was calculated using Bishop's simplified method. The results show that when the maximum infiltration capacity of the slope top soil is less than the rainfall intensity, slope failures may occur 14 hours after the rain starts. And when this happens, the rainfall duration is the deciding factor that affects the slope FS values. In short, cut slopes in Yen Bai may be stable in normal conditions after the excavation, but under the influence of tropical rain storms, their stability is always questionable.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.1
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• pp.43-50
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• 2004

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. Amrinone, a specific inhibitor of phosphodiesterase 3, has an antioxidant activity against PMNs. Therefore, we hypothesized that amrinone could attenuate PMNs-Induced cardiac dysfunction by suppression of reactive oxygen species (ROS) produced fby PMNs. In the present study, we examined the effects of amrinone on isolated ischemic (20 min) and reperfused (45 min) rat hearts perfused with PMNs. Amrinone at $25\;{\mu}M$, given to hearts during the first 5 min of reperfusion, significantly improved coronary flow, left ventricular developed pressure (P<0.001), and the maximal rate of development of left ventricular developed pressure (P<0.001), compared with ischemic/reperfused hearts perfused with PMNs in the absence of amrinone. In addition, amrinone significantly reduced myeloperoxidase activity by 50.8%, indicating decreased PMNs infiltration (p< 0.001). Superoxide radical and hydrogen peroxide production were also significantly reduced in fMLP- and PMA-stimulated PMNs pretreated with amrinone. Hydroxyl radical was scavenged by amrinone. fMLP-induced elevation of $[Ca^{2+}]_i$ was also inhibited by amrinone. These results provide evidence that amrinone can significantly attenuate PMN-induced cardiac contractile dysfunction in the ischemic/reperfused rat heart via attenuation of PMNs infiltration into the myocardium and suppression of ROS release by PMNs.

• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.402-410
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• 1997

Developing a salt core for squeeze casting process, two different salt cores(pure salt core and mixed salt core) were fabricated and investigated. Pure salt core was composed of 100% NaCl and mixed salt core was made by mixtures of NaCl with MgO(1%), $Na_2B_4O_7$(2%), and talc(1%) as a binder or a strengthening agent. Salt cores were compacted to various theoretical density, heat treated, and then squeeze-cast with molten Al alloy(AC8A). The compression strength of salt cores were measured and the squeeze-cast products were examined for shape retention, infiltration of molten metal into the cores, and microstructures. The shape of salt core compacted at above 75% of the theoretical density was maintained stably. The higher theoretical density of salt cores gave higher compression strength, and the compression strength of mixed salt core was higher than that of pure salt core. Namely at 90% theoretical density, the compression strength of mixed salt core was $6.3 kg/mm^2$, compared to $4.6 kgmm^2$ for pure salt core. At a squeeze casting pressure of $1000 kg/cm^2$, molten Al alloy was infiltrated into pure salt core of under 85% of the theoretical density. At squeeze casting pressure of $1000 kg/cm^2$, only mixed salt core above 90% of the theoretical density were valid, but the shape of the core was altered in the case of pure salt core at 90% of theoretical density. A key factor for developing a salt core for squeeze casting process was estimated as the ultimate compressive strength of salt core.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.481-501
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• 2007

Excessive rainfalls due to climatic changes can trigger an increase in rainfall-induced slope failures that pose real threats to both lives and properties. Many high slopes in residual soils could stand at a steep angle, but failed during or after rainfall. Commonly, these slopes have a deep groundwater table and negative pore-water pressures in the unsaturated zone above the groundwater table contribute to the shear strength of soil and consequently to factor of safety of the slope. Stability assessment of slope under rainfall requires information on rate of rainwater infiltration in the unsaturated zone and the resulting changes in pore-water pressure and shear strength of soil. This paper describes the application of unsaturated soil mechanics principles and theories in the assessment of rainfall effect on stability of slope through proper characterization of soil properties, measurement of negative pore-water pressures, seepage and slope stability analyses involving unsaturated and saturated soils. Factors controlling the rate of changes in factor of safety during rainfall and a preventive method to minimize infiltration are highlighted in this paper.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.828-837
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• 2006

Geotextiles consist of three major types of geosynthetic material (woven, non-woven and composite) and the functions of geotextiles are separation, reinforcement, filtration, drainage and as a moisture barrier. Although the many research scholar and engineer developed and established the design criteria and construction methodology, sustainable research still needed for optimum design methodology to the complicate field conditions. In this study, in-situ rainfall test performed to develop suitable filter system for sea dyke upper slope filter layer. In-situ rainfall test conducted for seven different filter system and measured the infiltration flux and pore pressure at various filter layer. Based on the test results, the double layered geotextile filter and sand transition system is most suitable for sea dyke upper filter layer because which system is effective for drainage of infiltration flow and minimize the deformation of sea dyke cover stone.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1137-1143
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• 1994

Through the numerical analysis of the capillary pressure-based Richards equation with and without the effect of the capillary hysteresis under the boundary condition having an antecedent rainfall. the moving tendency of the wetting front, the redistribution of the moisture content, infiltration rate, cumulative infiltration etc, were computed. The effect of the capillary hysteresis cannot be neglected in analyzing an unsaturated flow, and the more accurate results may be obtained by the consideration of the hysteresis effect. If the effect of the hysteresis cannot be considered, the analysis by the use of the main wetting curve may give more reliable result than that of the main drying curve.