• Journal of Drive and Control
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• v.15 no.4
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• pp.61-66
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• 2018

Almost every hydraulic system is equipped with a pressure relief valve, to maintain working pressure of the system at a pre-determined level. Thus, dynamic characteristics of such a relief valve, in conjunction with other hydraulic components, are important in designing the hydraulic control system. The single stage pressure relief valve is dynamically undesirable, due to relatively low viscous damping, that causes high frequency oscillations. This problem is overcome by introducing orifices in the inner pilot line, and drain line. In this study, for the single stage spool type pressure relief valve, the system equations were derived through an adequate linearisation and several simplifications were made, to use the transfer function formulation technique. All coefficients were evaluated and used, to make some results by using Matlab software. Results of analysis are compared with experimental results. In this study, parameters affecting stability of valve design are determined and suggested relative to the design.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.170-179
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• 2017

We investigated design requirements of feed water drain and hydrogen vent systems for the sodium-water reaction pressure relief system (SWRPRS) of the prototype generation IV sodium cooled fast reactor (PGSFR). We evaluated the areas of the gas vent pipe of the water dump tank and the length of the water drain pipe of the steam generator to rapid drain of the water steam inside the steam generator for the normal and refueling operations, respectively. We also calculated the diameter of the gas vent pipe of the sodium dump tank which met its design pressure.

• Journal of Chest Surgery
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• v.39 no.6 s.263
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• pp.475-478
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• 2006

Background: The simultaneous bilateral spontaneous pneumothorax is a rare clinical event. Contrary to the unilateral pneumothorax, the patients with simultaneous bilateral spontaneous pneumothorax sometimes complains of severe respiratory distress, cyanosis and chest pain without tention pneumothorax. It is often dangerous; therefore, the chest drain should be inserted immediately. Material and Method: Between March 1994 and February 2004, 802 patients were treated in our department for spontaneous pneumothorax. Among these, the simultaneous bilateral spontaneous pneumothorax developed in 14 patients (1.7%). Result: Out of fourteen patients, two females and twelve males presented with simultaneous bilateral spontaneous pneumothorax. The patient age ranged between 0 and 79 years with mean age of 31.2 years. In eleven patients, this was the first episode of pneumothorax. One patient had combined hemopneumothorax and two patients had combined pyopneurnothorax. Six patients had smoking history (42.8%, average 17.3 p-y). Five patients had pulmonary tuberculosis history and among these, two patients had active pulmonary tuberculosis. Three patients were died due to meconium-aspiration pneumonia (1 patient) and ARDS (Acute Respiratory Distress Syndrome) with pneumonia (2 patients). We treated these patients with nasal oxygen inhalation, chest drain insertion, thoracotomy, VATS (Video-Assisted Thoracoscopic Surgery) and chemical pleurodesis. Conclusion: The simultaneous bilateral spontaneous pneumothorax developed in 14 patients (1.7%) among 802 patients. Prompt insertion of chest drain is needed for a relief of severe symptoms, and to reduce the risk of recurrence, early thoracotomy or VATS should be performed rather than chest drain insertion only.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1221-1234
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• 2013

The purpose of this study is to suggest the methodology for the computation of uplift pressure and discharge of the seepage flow under gravity dam. A 3-dimensional FDM model is developed for this purpose and this model can simulate the saturated Darcian flow in heterogeneous media. For the verification of the numeric model, test simulation has been executed and the mass balance has been checked. The error does not exceed 3%. Using the developed model, The uplift pressure and seepage flow discharge under gravity dam has been calculated. The uplift pressure shows the similar pattern, comparing with the result of flow-net method. As the length of grout curtain increases, the uplift pressure decreases linearly, but the seepage flow discharge shows the non-linear decreasing pattern. The coefficients of the formulas in the dam-design criteria have been analysed, and ${\alpha}=1/3$ corresponds to the value when the length of curtain grout is 70% of the aquifer height. The uplift pressure near the pressure relief drain has the big curvature vertically and horizontally. The developed model in this study can be used for the evaluation of the effects of seepage flow under gravity dam.