• Journal of Chest Surgery
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• v.9 no.1
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• pp.20-26
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• 1976

Author has performed experimental study on hemodynamic changes of lung following radical hilar stripping and contralateral pulmonary artery ligation. In view of hemodynamic changes in group 1 (right pulmonary artery ligation only) and group 2(left hilar stripping+right pulmonary artery ligation). group 2 showed remarkable decrease rate in oxygen uptake (P<0.001) and total pulmonary blood flow(P<0.001), and the more increase rate in mean pulmonary artery pressure(P<0.02) and total pulmonary vascular resistance (P<0.001). Meanwhile, the decrease percent of left lung vascular resistance was lower than group 1(P<0.001). The hemodynamic changes in group 1 returned to control range two weeks later. In the group 2, two dogs were expired as a result of atelectasis and pulmonary hypertension. Among allying 8 dogs, five months after operation, follow up studies performed in two dogs, which showed normal pulmonary hemodynamics similar to preoperative data. The altered blood gas values and decreased oxygen uptake are more remarkable in denervated lung, which may due to pulmonary hypertension and partly retained more secretion in bronchial trees than usual. Important factors of raising pulmonary vascular resistance and pulmonary artery pressure are considered as the increased blood flow to remaining left lung and dysfunction of pulmonary vascular bed to accept the increased blood flow after denervation. Loss of nerve innervation had a influence, to some extent, to the decrease of oxygen uptake and the increase of pulmonary vascular resistance and pulmonary artery pressure. There can be little question that denervation does impair the pulmonary hemodynamics, however, intact pulmonary nerve innervation is not absolutely essential for survival of the animal.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.792-797
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• 2015

In this study, three softwood species were treated with water-soluble melamine resin by different concentration and treatment time under vacuum pressure for improving mechanical property, abrasion resistance, and incombustibility. After the treatment, a compreg was manufactured and then evaluated on physical properties. Additionally, incombustibility of compreg was determined by comparing with a wood that was treated by spraying a water-soluble fire retardant on surface. As concentration of resin increased, bending strength and Brinell hardness increased as well as abrasion resistance, but there was no correlation on treatment and mechanical properties by treatment time. The wood impregnated by water-soluble melamine resin under vacuum pressure showed better incombustibility than that of a water-soluble fire retardant sprayed wood. Therefore, this treatment could be used for improving incombustibility of wood.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.265-270
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• 2018

In this study, the flow analysis due to the car body configuration of air breather was carried out. As the resistance force whose flow affects car body has been studied, it is published that the electricity can be decreased. When the inner pressure of air breather is evaluated, there is the study of efficiency in order to raise the flow rate of inner body. At a total of five models, it is shown that the air resistance and pressure happen differently and the air pressure of side flow is changed. This study result was analyzed by using the analysis program of ANSYS, a study model was modelled using the CATIA V5 modelling program. It was investigated that the air flow rate was distributed uniformly as the curved surface of air breather configuration increases. It is thought as the most effective design method to design the air breather by considering the effect on the air resistance and flow. Also, through the design of the vehicle's airbrid configuration, the design of the product can incorporate a aesthetic sense into the design.

• Journal of the Korean GEO-environmental Society
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• v.4 no.2
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• pp.57-64
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• 2003

Marston (1913) and Spangler's (1982) theory was widely used in the analysis of the earth pressure of the narrow and long excavated ditch type backfield ground. Their theory was more clearly explained by expressing the minor principle stress arch connecting the minor principle stress link induced by interaction between the excavated wall surface and the backfilled earth. which was done by R.L. Handy(1985). Later C.G. Kellogg(1993) extended the study from vertical symmetric to incline symmetric in the backfill space type research. In the C.G. Kellogg's study, it is assumed that the resistance of wall friction on the sloping wall could be replaced by the internal friction angle in the sloping section bottom. In the study, the resistance of wall friction in the sloping section bottom, which was applied by C.G. Kellogg, would be different in magnitude with the resistance of wall friction in sloping section. The magnitude is expected to affect in the earth pressure calculation and verified by the soil test box, the C.G. Kellogg's theory, the numerical analysis and the modified C.G. Kellogg's theory considering the friction resistance to influence the incline wall.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.100-108
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• 2006

Time-resolved current and voltage measurements for an inductive automotive spark system were made. Also presented are measurements of the total energy delivered to the spark gap. The measurements were made in air for a range of pressures from 1-18atm, at ambient temperatures. The measured voltage and current characteristics were found to be a function of many ignition parameters; some of these include: spark gap distance, internal resistance of the spark plug and high tension wire, and pressure. The voltages presented were measured either at the top of the spark plug or at the spark gap. The measurements were made at different time resolutions to more accurately resolve the voltage and current behavior throughout the discharge process. This was necessary because the breakdown event occurs on a time scale much shorter than the arc and glow phases. The breakdown, are, and glow voltages were found to be functions of spark plug resistance, gas density, and spark plug gap as expected from the literature. Spark duration was found to decrease as either pressure or gap was increased. The transition from the arc to glow phase is usually distinguished by a sudden rise in the voltage across the gap. At pressures above about 7atm this transition was not observed suggesting that a glow phase was not present. Energy delivered to the gap increased with increasing pressure. The effective resistance of the spark gap during discharge was about twice as large for the glow phase as the arc phase.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.551-563
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• 2007

Numerical analysis for flow characteristics of a twin skeg container ship was carried out according to skeg vertical angles($0^{\circ}$, $10^{\circ}$, $20^{\circ}$) and skeg distances(16m, 20m, 24m) by using a commercial CFD code, FLUENT. Computed: pressure distributions, wake distributions and resistance coefficients have been compared with experimental and WAVIS results carried out by MOERI. Flow characteristics from numerical analysis such as nominal wake fractions, wake distribution and directions of the transverse vectors give good agreement with WAVIS results, even though there are quantitative discrepancy comparing with experimental measurements at the propeller plane. It is found that the better resistance performance can be obtained with the increase of the skeg vertical angle and the decrease of the skeg distance, which are mainly caused by viscous pressure resistance due to the skeg form and pressure recovery around the skeg. In addition, a vertical angle of the skeg gives more effect to the resistance coefficient comparing with the skeg distance. On the basis of results of the present study, it shows that numerical analysis using the commercial code, FLUENT, is useful and efficient tool for the evaluation of the complex stern hull form with twin-skegs.

• Journal of Adhesion and Interface
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• v.18 no.4
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• pp.166-170
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• 2017

In this study, acrylic rubber pressure sensitive adhesives was polymerized with 2-ethylhexyl acrylate, styrene, butadiene, 2-hydroxyethyl acrylate, and acrylic acid by controlling the initiator content. The initial tackiness, peel strength, holding power, and heat resistance of the PSAs were investigated by changing the content of tackifier and curing agent. The results showed that the initial tackiness and peel strength increased as the content of tackifier increased, whereas the holding power decreased. Also, the results exhibited that that the initial tackiness, peel strength, and heat resistance decreased as the content of curing agent increased, whereas the holding power and decreased.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.297-316
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• 2010

Membrane fouling is one of the major operational concerns of membrane processes which results in loss of productivity. This paper investigates the ultrafiltration (UF) results of synthetic oil-in-water (o/w) emulsion using flat sheets of polysulfone (PSf) membrane synthesized with four different compositions. The aim is to identify the mechanisms responsible for the observed permeate flux reduction with time for different PSf membranes. The experiments were carried out at four transmembrane pressures i.e., 68.9 kPa, 103.4 kPa, 137.9 kPa and 172.4 kPa. Three initial oil concentrations i.e., 75 $mgL^{-1}$, 100 $mgL^{-1}$ and 200 $mgL^{-1}$ were considered. The resistance-in-series (RIS) model was applied to interpret the data and on that basis, the individual resistances were evaluated. The significances of these resistances were studied in relation to parameters, namely, transmembrane pressure and initial oil concentration. The total resistance to permeate flow is found to increase with increase in both transmembrane pressure and initial oil concentration while for higher oil concentration, resistance due to concentration polarization is found to be the prevailing resistance. The applicability of the constant pressure filtration models to the experimental data was also tested to explain the blocking process. The study shows that intermediate pore blocking is the dominant mechanism at the initial period of UF while in the later period, the fouling process is found to approach cake filtration like mechanism. However, the duration of pore blocking mechanism is different for different membranes depending on their morphological and permeation properties.

• Geomechanics and Engineering
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• v.28 no.3
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• pp.265-281
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• 2022

A set of slurry shield test system capable of cutter cutting and slurry automatic circulation is used to investigate the deformation characteristics, the evolution characteristics of support resistance and the distribution and evolution process of earth pressure during excavating and collapsing of slurry shield tunneling in circular-gravel layer. The influence of cover-span ratio on surface subsidence, support resistance and failure mode of excavation face is also discussed. Three-dimensional numerical calculations are performed to verify the reliability of the test results. The results show that, with the decrease of the supporting force of the excavation face, the surface subsidence goes through four stages: insensitivity, slow growth, rapid growth and stability. The influence of shield excavation on the axial earth pressure of the front soil is greater than that of the vertical earth pressure. When the support resistance of the excavation face decreases to the critical value, the soil in front of the excavation face collapses. The shape of the collapse is similar to that of a bucket. The ultimate support resistance increase with the increase of the cover-span ratio, however, the angle between the bottom of the collapsed body and the direction of the tunnel excavation axis when the excavation face is damaged increase first and then becomes stable. The surface settlement value and the range of settlement trough decrease with the increase of cover-span ratio. The numerical results are basically consistent with the model test results.

• Tuberculosis and Respiratory Diseases
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• v.42 no.6
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• pp.913-922
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• 1995

Background: When we define the pressure of pulmonary vasculature in which a recruitment of blood flow occurs as $P_I$ and the proportion of change in pulmonary artery to that in cardiac output as IR and then we compare PI and IR with pulmonary vascular resistance, we would find some problems in pulmonary vascular resistance. In other words, it is the theory that, IR should be increased mainly in pulmonary embolism in which decreases the cross sectional area of pulmonary vasculature. But there are many contradictory reports resulted from various researches and the fact is known widely that any difference exists between PVR and PI, IR. For this reason, the purpose of this study is to observe how PI and IR change at the time of the outbreak and during treatment of the pulmonary embolism, and to find out the meaning of these new indicators and the difference from the pulmonary vascular resistance used generally when we subdivide the pulmonary vascular resistance into PI and IR. Method: After making AV fistula in experimental dog, we controlled cardiac output at the intervals of 15 minute in case of three kinds(all AV fistula are obstructed, only one of fistula is open and all of fistula is open), and after evoking massive pulmonary embolism with radioactive autologous blood clots, we measured the mean pulmonary artery pressure, and calculated PI and IR. We observed the pattern of change in PI and IR, without giving the control group any specific treatment and with injecting intravenously rtPA in the Group 1 and Group 2 at the dose of 1mg per kg, for 15 minutes fot the former and 3 hours for the latter. Result: 1) Pulmonary vascular resistance showed a change similar to that of pulmonary artery pressure and in all three group, PVR increased significantly, but group 1 and group 2 showed tendency that PVR keeps on decreasing after treatment, and the rate of decrease in group 1 is more rapid than group 2 significantly. 2) Both intersection(PI) and degree(IR) are proved statistically significant, in view of the straight line relationship between cardiac output and pulmonary artery pressure, calculated by minimal regression method. 3) PI changed similarly to pulmonary vascular resistance, while in the IR which is theoretically more similar to PVR, there was no significant difference or change after rtPA infusion. Conclusion: In the pulmonary embolism, Both change in IR which means real resistance of pulmonary vasculature and PI which was developed due to secondary vasoconstriction by pulmonary embolism are reflected same time.