• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.723-729
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• 2019

Turbochargers are an effective device to reduce the fuel consumption. In this study, the mass flow rate of pulsating flow in the twin-scroll turbocharger for the gasoline engine of passenger vehicles was measured. Pulsating flow was achieved using a pulse generator and the mass flow rate of the unsteady pulsating flow was analyzed by comparing it with those of the steady flow. The pulse generator consisted of a rotating upper plate and a fixed lower plate. To measure the mass flow rate of unsteady flow, the orifice flow meter equipped with the difference pressure transducer was used. To analyze the low speed performance of the turbocharger, the measurement was carried out in the speed of turbocharger from 60,000rpm to 100,000rpm. The mass flow parameters of the unsteady pulsating flow showed a large difference compared to those of the steady flow. Those of the unsteady flow showed the hysteresis loop surrounding the mass flow parameters of the steady flow and the maximum variation of the mass flow parameters were 5.0 times those of the steady flow. This phenomenon is the result of the filling and emptying the turbine volute space due to pulsating flow.

• Journal of the Korean Geographical Society
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• v.28 no.3
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• pp.213-226
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• 1993

In Korea, the urban studies of geography have mainly dealt with such a series of research as system of urban place and internal structure of urban area. The existing studies have been carried out with ecological approach. Ecologists, now a days, regard organiation and transfor-mation of the urban space as the process of invasion, succession, and segregation. However it is more proper that cities should be considered not as fragmantary objects, as some ecologists insist, but as synthetic ones in social structure. This research, with adopting a case of the renewasl of central area in Seoul, tried to make it clear that the formation and transition of the city is a product of social structure and examined polical and economic logic which exists in variation of urban space in detail. The results of this study are as follows; Urban renewal of central area is closely related with production and reproduction in capitalist society. In urban center, as business activities had increased since 1973 due to decen-tralization of production process, the necessity of reorganizing the land use in existing central area accordingly increased. The urban renewal program of central area in Seoul was inrroduced under such situation. The urban renewal of central area reflecting the capital logic has changed the central area with six hundred year's tradition. From the urban renewal of central area, not only was the central area, which traditionally had been mixed with various fun-ctions, simplified into the unitary area of busi-ness, but also physical landscape changed. As the land lot in renewal area expanded into regular shape, buildings became larger and taller. The program tremendously raised the price of related area. Aiming at these profits caused by the raised price, a great number of capitalists participated in the program. And as the benefit ratio of the manufacture sector continuously dropped with the economic recession, the pro-gram was carried out much more vigorously. That was because the idle capital accumulated during the recession was invested in property sector and was self-proliferated. The urban renewal raised the land value of central area and drove out the people living in this area. The people moved into the whole parts of the city resulting diffused squatter settlements. And the urban changes in central area were results of the policy of municipal authorities, who supported and systematized the changes lawfully and administratively, as well as reali-zation of capital logic. Due to the renewal policies of central area in Seoul, much more renewals by the only capitalists were carried out than those by the people themselves living in that area. The integration of land ownership in the law of urban renewal shows the reason of that. Moreover, the law allows the third deve-loper to participate in the tasks and admits the land expropriation rights. The municipal autho-rities guaranteed the profitability of the tasks through finacial aid, tax benifit, and relaxation of regulations for construction. As examined above, the changes in the land use of urban space have been led not by the ecological process of development of the city itself, but by the restructuring of capitalism and the intervention of the government authorities.

• The Korean Journal of Physiology
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• v.15 no.2
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• pp.103-109
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• 1981

In order to determine the dose-response relationship of ethanol on blood pressure and renal function, 2 doses of ethanol were intubated into albino rats. For a direct measurement of arterial blood pressure, a polyethylene catheter(PE 10) was implanted in the abdominal aorta, and the other end of the catheter was pulled out of the back of the neck. The experiment was conducted after the rats recovered from the surgery. After emptying their bladders, the rats were placed in a metabolism cage. Mean arterial pressure (MAP) was measured and arterial blood samples were collected through the catheter. Following the collection of the control urine sample, 1 ml of 10 g% (low dose), or 30 g% (high dose) of ethanol/100 g BW was intubated. 1 ml of water/100 g BW was intubated into the control group. MAP and blood samples were taken every hour, and urine samples were collected every 90 min for 3 hours. Blood alcohol concentrations reached a peak at 1 hour (low dose: $105.0{\pm}7.5$, high dose: $214.7{\pm}20.2\;mg%$) and decreased linearly thereafter. Following alcohol ingestion, MAP began to decrease at 15 min and remained at a significantly low level thoughout the 3 hours experimental period(low dose: $112{\pm}2{\rightarrow}102{\pm}4$, high dose: $117{\pm}2{\rightarrow}100{\pm}8\;mmHg$). Urine Flow increased markedly during the first 90 min of ethanol ingestion (low dose: $0.88{\pm}0.20{\rightarrow}1.04{\pm}0.22$, high dose: $0.56{\pm}0.11{\rightarrow}1.35{\pm}0.18\;ml/1.5\;hr$) and decreased during the second 90 min period(low dose: $0.25{\pm}0.06$, high dose: $0.22{\pm}0.06\;ml/1.5\;hr$). Urine flow of the control group decreased gradually during the experiment $(0.88{\pm}0.10{\longrightarrow}0.59{\pm}0.09{\rightarrow}0.45{\pm}0.09\;ml/1.5\;hr)$. These results indicate that the blood-pressure-lowering and diuretic effects of ethanol are dose-related: higher doses of ethanol produce a greater decrease in blood pressure and greater diuresis.