• Fire Science and Engineering
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• v.15 no.1
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• pp.23-33
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• 2001

The utility tunnels are the important facility as a mainstay of country because of the latest communication developments. However, the utilities tunnel is difficult to deal with in case of a fire accident. When a cable burns, the black smoke containing poisonous gas will be reduced. This black smoke goes into the tunnel, and makes it difficult to extinguish the fire. Therefore, when there was a fire in the utility tunnel, the central nerves of the country had been paralyzed, such as property damage, communication interruption, in addition to inconvenience for people. This paper is based on the fire occurred in the past, and reenacting the fire by making the real utilities tunnel model. The aim of this paper is the scientific analysis of the character image of the fire, and the verification of each fire protection system whether it works well after process of setting up a fire protection system in the utilities tunnel at a constant temperature. The fire experiment was equipped with the linear heat detector, the fire door, the connection water spray system and the ventilation system in the utilities tunnel. Fixed portion of an electric power supply cable was coated with a fire retardant coating, and a heating tube was covered with a fireproof. The result showed that the highest temperature was $932^{\circ}c$ and the linear heat detector was working at the constant temperature, and it pointed at the place of the fire on the receiving board, and Fixed portion of the electric power supply cable coated with the fire retardant coating did not work as the fireproof. The heating tube was covered with the fireproof about 30 minutes.

• Journal of Chest Surgery
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• v.31 no.8
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• pp.739-748
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• 1998

Background: It has been well documented that transient occlusion of the coronary artery causes myocardial ischemia and finally cell death when ischemia is sustained for more than 20 minutes. Extensive studies have revealed that ischemic myocardium cannot recover without reperfusion by adequate restoration of blood flow, however, reperfusion can cause long-lasting cardiac dysfunction and aggravation of structural damage. The author therefore attempted to examine the effect of postischemic reperfusion on myocardial ultrastructure and to determine the rationales for recanalization therapy to salvage ischemic myocardium. Materials and methods: Young Holstein-Friesian cows(130∼140 Kg body weight; n=40) of both sexes, maintained with nutritionally balanced diet and under constant conditions, were used. The left anterior descending coronary artery(LAD) was occluded by ligation with 4-0 silk snare for 20 minutes and recanalized by release of the ligation under continuous intravenous drip anesthesia with sodium pentobarbital(0.15 mg/Kg/min). Drill biopsies of the risk area (antero-lateral wall) were performed at just on reperfusion(5 minutes), 1-, 2-, 3-, 6-, 12-hours after recanalization, and at 1-hour assist(only with mechanical respiration and fluid replacement) after 12-hour recanalization. The materials were subdivided into subepicardial and subendocardial tissues. Tissue samples were examined with a transmission electron microscope (Philips EM 300) at the accelerating voltage of 60 KeV. Results: After a 20-minute ligation of the LAD, myocytes showed slight to moderate degree of ultrastructural changes including subsarcolemmal bleb formation, loss of nuclear matrix, clumping of chromatin and margination, mitochondrial destruction, and contracture of sarcomeres. However, microvascular structures were relatively well preserved. After 1-hour reperfusion, nuclear and mitochondrial matrices reappeared and intravascular plugging by polymorphonuclear leukocytes or platelets was observed. However, nucleoli and intramitochondrial granules reappeared within 3 hours of reperfusion and a large number of myocytes were recovered progressively within 6 hours of reperfusion. Recovery was apparent in the subepicardial myocytes and there were no distinct changes in the ultrastructure except narrowed lumen of the microvessels in the later period of reperfusion. Conclusions: It is likely that the ischemic myocardium could not be salvaged without adequate restoration of coronary flow and that the microvasculature is more resistant to reversible period of ischemia than subendocardium and subepicardium. Therefore, thrombolysis and/or angioplasty may be a rational method of therapy for coronarogenic myocardial ischemia. However, it may take a relatively longer period of time to recover from ischemic insult and reperfusion injury should be considered.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.10
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• pp.1445-1452
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• 2002

The present experiment was carried out to study the utilization of substrates in the mammary gland of crossbred Holstein Friesian during feeding on different types of roughage. Sixteen pregnant crossbred Holstein heifers consisted of two breed types of eight animals each; Holstein Friesian${\times}$Red Sindhi (50:50=50%HF) and Holstein Friesian${\times}$Red Sindhi (87.5:12.5=87.5%HF). Animals were divided into four groups of the same breed type in each group which were fed with either rice straw treated with 5% urea or pangola hay (Digitaria decumbens) as the source of roughage throughout the experiments. Four consecutive experimental periods were carried out in late pregnancy (20-23 days before parturition), early lactation (30 days postpartum), mid-lactation (120 days postpartum) and late lactation (210 days postpartum). Measurement of mammary blood flow in combining with measurement of AV difference was performed for the mammary uptake of substrates. In the period of lactation, udder blood flow was nearly three times higher than that of late pregnant period (p<0.05) in both 50%HF and 87.5%HF feeding on either hay or urea treated rice straw. During mid- and late lactation of both groups of 87.5%HF animals, mammary blood flow and milk yield showed decrease when compared to those during the early lactating period while the trends for persistency were apparent in both groups of 50%HF animals throughout experimental periods. The mean arterial plasma concentrations of glucose, acetate, $\beta$-hydroxybutyrate and free glycerol in each group remained constant throughout experimental periods. During late pregnancy in all groups, the AV difference and extraction ratio of glucose, $\beta$-hydroxybutyrate and triacylglycerol across the mammary gland markedly lowered (p<0.05), which coincided with a lower net uptake by the mammary gland in comparison to the early lactating period. The mean arterial plasma concentration, AV difference and extraction ratio for acetate showed no significant differences between late pregnancy and the early lactating period. The AV difference of free glycerol showed apparent release from mammary tissue during late pregnancy in all groups. In mid- and late lactation, the mammary uptake for glucose, acetate and $\beta$-hydroxybutyrate in both groups of 87.5%HF animals showed apparent decrease as compared to that in the early lactating period, whereas no appearances were observed in 50%HF animals feeding either hay or urea treated rice straw. The mean arterial plasma concentrations for free fatty acid (FFA) and triacylglycerol (C16 to C18) were higher in late pregnancy than in early lactation in both types of crossbred animals. The values of AV difference and the net uptake by the mammary gland for FFA were variable during late pregnancy and lactating periods in all groups. There were no significant differences for AV difference, extraction ratio and net uptake of triacylglycerol during lactation advance in both groups of 50%HF and 87.5%HF animals feeding either hay or urea treated rice straw. These results suggest that the adaptations to either hay or urea treated rice straw by the mammary gland of crossbred HF animals allow for an adequate nutrient supply during pregnancy and lactation. There is no difference in the mode of mammary uptake of substrates in the same crossbred animals in response to feeding hay or urea treated rice straw. The differences in utilizing nutrients by the mammary gland for milk production between 87.5%HF and 50%HF animals would be dependent on changes in both intra-mammary factors and extra-mammary factors.

• Journal of Korea Water Resources Association
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• v.55 no.6
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• pp.437-446
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• 2022

In April 2020, the Korean government decided to operate the Hwacheon reservoir, a hydropower reservoir to supply water, and it is currently under pilot operation. Through the pilot operation, the Hwacheon reservoir is the first among the hydropower reservoirs in Korea to make a constant release for downstream water supply. In this study, the water supply capacity of the Hwacheon reservoir was estimated using the inflow data of the Hwacheon reservoir. A simulation model was developed to calculate the water supply that satisfies both the monthly water supply reliability of 95% and the annual water supply reliability of 95%. An optimization model was also developed to evaluate the water supply capacity of the Hwacheon reservoir. The inflow data used as input data for the model was modified in two ways in consideration of the impact of the Imnam reservoir. Calculating the water supply for the Hwacheon reservoir using the two modified inflows is as follows. The water supply that satisfies 95% of the monthly water supply reliability is 26.9 m³/sec and 24.1 m³/sec. And the water supply that satisfies 95% of the annual water supply reliability is 23.9 m³/sec and 22.2 m³/sec. Hwacheon reservoir has a maximum annual water supply of 777 MCM (Million Cubic Meter) without failure in the water supply. The Hwacheon reservoir can supply 704 MCM of water per year, considering the past monthly power generation and discharge patterns. If the Hwacheon reservoir performs a routine operation utilizing its water supply capacity, it can contribute to stabilizing the water supply during dry seasons in the Han River Basin.