• International Journal of Highway Engineering
• /
• v.13 no.2
• /
• pp.21-29
• /
• 2011

Recently, typhoons or heavy rainfalls frequently occurred because of the effect of global warming, which caused serious damage such as landslide of mountain road, debris flow and uplift seepage pressure. Uplift seepage pressure induced on the pavement of mountain roads may cause serious pavement damage. It was known that subsurface drainage method is very effective to reduce uplift seepage pressure. Suitable permeability and stiffness of drainable base is very important to have the effectiveness of subsurface drainage. In this study, optimum particle size distribution of drainable base is investigate to meet the required permeability and bearing capacity of drainable base.

• Journal of Chest Surgery
• /
• v.18 no.1
• /
• pp.79-85
• /
• 1985

The effect of graded increments in positive end-expiratory pressure [PEEP] on hemodynamics required to ventilate 8 critically ill patients is reported. Acute respiratory insufficiency was a cause of death in only one patient of drug inoxication among the 8 patients studied. The cardiac output was not changed significantly after the increment of PEEP to the level of 20 cm H2O. The heart rate was increased significantly from 15 cm H2O PEEP [P<0.01] as compared to 0 cm H2O PEEP; and the stroke volume was decreased significantly from 15 cm H2O PEEP [P<0.05]. The blood pressure was not affected at any level of PEEP, but the pulmonary artery pressure was elevated significantly at 10 cm H2O PEEP [P<0.01]. The right ventricular transmural filling pressure was not affected at the level of 10 cm H2O PEEP, but from 15 cm H2O PEEP it was increased significantly. With the increment of PEEP, the left ventricular stroke work index was decreased slightly; and at 20 cm H2O PEEP, it was decreased significantly. The right ventricular stroke work index was increased only at 10 cm H2O PEEP. The systemic vascular resistance was decreased significantly from 15 cm H2O PEEP [P<0.01].

• Journal of Chest Surgery
• /
• v.28 no.5
• /
• pp.437-442
• /
• 1995

We developed an experimental model of brain death using dogs. Brain death was caused by increasing the intracranial pressure[ICP suddenly by injecting saline to an epidural Foley catheter in five female mongrel dogs[weight, 20-25Kg .Hemodynamic and electrocardiographic changes were evaluated continuously during the process of brain death. 1. Abrupt rise of ICP after each injection of saline followed by a rapid decline to a new steady-state level within 15 minutes and the average volume required to induce brain death was 7.6$\pm$0.8ml.2. Body temperature, heart rate, mean pulmonary arterial pressure, left ventricular[LV enddiastolic pressure and cardiac output was not changed significantly during the process of brain death, but there was an increasing tendency.3. Mean arterial pressure and LV maximum +dP/dt increased significantly at the time of brain death.4. Hemodynamic collapse was developed within 140 minutes after brain death.5. Marked sinus bradycardia followed by junctional rhythm was seen in two dogs and frequent VPB`s with ventricular tachycardia was observed in one dog at the time of brain death. Hyperdynamic state develops and arrhythmia appears frequently at the time of brain death. Studies on the effects of brain death on myocardium and its pathophysiologic mechanism should be followed in the near future.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.6
• /
• pp.111-121
• /
• 2000

Generally, the hydraulic pressures are used for transmitting the force. Therefore, a highly reliable and inexpensive control system has been required for a passenger car. The control-ability of active suspension system is strongly affected by the performance of pressure control valve in the view of dynamic response and energy consumption. In this study, we suggested main design parameters for the optimum design of proportional pressure control valve. The mathematical simulation model was derived from the quarter type model which consisted a valve and hydraulic damper for the purpose of analyzing the valve characteristics. Experiments were performed to confirm the performance of the valve and computations were carried out to ascertain the usefulness of the developed program. The results from computations fairly coincide with those from experiments. This has been achieved by developing the servomechanism valve which comprises the simple combination of a solenoid, a spool valve and a poppet valve. The results from experiments and computations show the development process of optimum proportional pressure control valve in the hydraulics system.

• Geomechanics and Engineering
• /
• v.22 no.1
• /
• pp.35-48
• /
• 2020

This paper provides methods for the deterministic and reliability-based design of the support pressures necessary to prevent tunnel face collapse. The deterministic method is developed by extending the use of the unique load multiplier, which is embedded within OptumG2/G3 with the intention of determining the maximum load that can be supported by a system. Both two-dimensional and three-dimensional examples are presented to illustrate the applications. The obtained solutions are validated according to those derived from the existing methods. The reliability-based method is developed by incorporating the Response Surface Method and the advanced first-order second-moment reliability method into the bisection algorithm, which continuously updates the support pressure within previously determined brackets until the difference between the computed reliability index and the user-defined value is less than a specified tolerance. Two-dimensional reliability-based support pressure is compared and validated via Monte Carlo simulations, whereas the three-dimensional solution is compared with the relationship between the support pressure and the resulting reliability index provided in the existing literature. Finally, a parametric study is carried out to investigate the influences of factors on the required support pressure.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.52 no.2
• /
• pp.1-9
• /
• 2010

This study was carried out to comparison of coefficient of consolidation and the prediction of excess pore water pressure in agricultural reservoir on soft clay ground. For the purpose of verification of the proposed equation, laboratory model tests and field tests were performed and excess pore water pressure was compared to those predicted with the Terzaghi's method. The predicted excess pore water pressure according to ponding was very applicable to practice because it was close to the observed data. Also, for the comparison of coefficient of consolidation, the oedometer, constant rate of strain (CRS), and Rowe cell tests were performed. The coefficient of consolidation at the Rowe cell and CRS tests showed a greate increase than in the oedometer test. The ratio of the vertical and horizontal coefficient of consolidation showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to predicting the required consolidation period in agricultural reservoir.

• Journal of the Korean Institute of Gas
• /
• v.2 no.4
• /
• pp.1-6
• /
• 1998

In order to increase design efficiency, it is required to design steam boiler pressure parts systematically considering daily start-stop operation and load variation. The objective of this research is to develope an integrated system for increasing design efficiency of boiler pressure parts. The developed system consists of three program modules: (1) flexibility design module for the header stub considering fatigue life, (2) fatigue limit calculation and life evaluation module for the thick-walled boiler pressure part under cyclic operation using TRD301 code, (3) drawing automation module for the header and drum producing design drawings, welding data and bill of materials.

• 유체기계공업학회:학술대회논문집
• /
• 2000.12a
• /
• pp.259-264
• /
• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.7
• /
• pp.343-350
• /
• 2014

Regardless of the building design scenarios, evaluation of high-rise buildings required to have smoke-proof enclosures that are provided with a smoke management system. The goal of the smoke management system design is to make sure the pressure differentials at every story within the building fall within the allowable pressure range. If the minimum design pressure is not met, smoke may enter the stair. If the provided pressure is too great, it becomes difficult for occupants to open the doors, while attempting to egress. Ensuring that the pressure differential between the vestibule and the floor is within the prescribed range becomes challenging, due to natural effects on the building, such as the stack effect. In this research, smokeproof enclosure design scenarios were evaluated; and as a result, separation levels for compartmentation were deduced, in the balancing of pressurized-vestibule smoke control systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1290-1295
• /
• 2006

The 120 meters high pressure feedwater heater drain piping in nuclear power plant had been suffered by excessive vibration from the beginning of power generation. As time goes by, the piping vibration was beyond the allowable limit and an appropriate countermeasure was required to prevent the fatigue failure of the pipeline from the abnormal vibration. In this study, the vibrational characteristics of high pressure feedwater heater drain piping and the countermeasure for abnormal vibration were investigated. Among the several vibration reduction methods, the piping layout changed by making the smooth pipeline was applied to the high Pressure feedwater heater drain piping in nuclear Power plant. Applying the countermeasure, the vibration level was found to reduce over 54 percents and was satisfied under the allowable velocity at the full-power operation condition.