• Journal of the Korean GEO-environmental Society
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• v.24 no.8
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• pp.5-11
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• 2023

Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

• Journal of Korean Neurosurgical Society
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• v.60 no.1
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• pp.89-93
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• 2017

Infratentorial cerebral hemorrhage due to a direct carotid-cavernous fistula (CCF) is very rare. To our knowledge, only four such cases have been reported. Cerebellar hemorrhage due to a direct CCF has not been reported. We describe a 63-year-old female who presented with reduced consciousness 3 days after undergoing a maxillectomy for maxillary cancer. Computed tomography showed a cerebellar hemorrhage. Magnetic resonance angiography showed a left-sided direct CCF draining into the left petrosal and cerebellar veins through the left superior petrosal sinus (SPS). Her previous surgery had sacrificed the pterygoid plexus and facial vein. Increased blood flow and reduced drainage could have led to increased venous pressure in infratentorial veins, including the petrosal and cerebellar veins. The cavernous sinus has several drainage routes, but the SPS is one of the most important routes for infratentorial venous drainage. Stenosis or absence of the posterior segment of the SPS can also result in increased pressure in the cerebellar and pontine veins. We emphasize that a direct CCF with cortical venous reflux should be precisely evaluated to determine the hemodynamic status and venous drainage from the cavernous sinus.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.8 no.1
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• pp.15-21
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• 2012

Extraction of all nonrestorable teeth prior to bone marrow transplantation is the major dental management of the patient being prepared for the transplantation. But, there are four principal causes for excessive bleeding in the immediate postextraction phase ; (1) Vascular wall alteration (wound infection, scurvy, chemicals, allergy) (2) Disorders of platelet function (3) Thrombocytopenic purpuras (4) Disorders of coagulation (liver disease, anticoagulation drug-heparin, coumarin, aspirin, plavix) If the hemorrhage from postextraction wound is unusually aggressive, the socket must be packed with local hemostatic agent and wound closure & pressure dressing are applied. But, in dental alveoli, local hemostatic agent (gelfoam, surgcel etc) may absorb oral microorganisms and cause alveolar osteitis (infection). This is a case report of bleeding and infection control by suture, pressure packing and iodoform gauze drainage on infected active bleeding extraction socket under sedation and local anesthesia in a 57-years-old multiple disabled patient with anticoagulation drug.

• Geomechanics and Engineering
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• v.13 no.2
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• pp.285-300
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• 2017

Shallow coal resources are increasingly depleted, the mining has entered the deep stage. Due to "High stress, high gas, strong adsorption and low permeability" of coal seam, the gas drainage has become more difficult and the probability of coal and gas outburst accident increases. Based on the flow solid coupling theory of coal seam gas, the coupling model about stress and gas seepage of coal seam was set up by solid module and Darcy module in Comsol Multiphysics. The gas extraction effects were researched after applying hydraulic technology to increase permeability. The results showed that the effective influence radius increases with the expanded borehole radius and drainage time, decreases with initial gas pressure. The relationship between the effective influence radius and various factors presents in the form: $y=a+{\frac{b}{\left(1+{(\frac{x}{x_0})^p}\right)}}$. The effective influence radius with multiple boreholes is obviously larger than that of the single hole. According to the actual coal seam and gas geological conditions, appropriate layout way was selected to achieve the best effect. The field application results are consistent with the simulation results. It is found that the horizontal stress plays a very important role in coal seam drainage effect. The stress distribution change around the drilling hole will lead to the changes in porosity of coal seam, further resulting in permeability evolution and finally gas pressure distribution varies.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.18-23
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• 2014

Foam extinguishing agent is widely used for extinguishing combustible liquid fires. Compared to other foam type extinguishing agents, protein foam has relatively low cost and low toxicity and produces stable foam blanket which is excellent in heat resistance and sealability, despite it has weak fluidity. Therefore the study investigated foaming characteristics followed by various factors affecting the fluidity of the protein foam extinguishing agent. The extinguishing characteristics differentiated by the changes in fluidity were also experimented. Foaming performance was compared by measuring the expansion ratio and the 25% drainage time. Moreover, the 25% drainage time and the extinguishing time was compared. The results showed that the 25% drainage time and the expansion ratio were increased as the pressure of nozzle and the concentration of hydrolyzed protein liquid enlarged. However the foaming and extinguishing performance were not improved when the condition exceeded certain level of pressure and concentration. The fastest fire extinguishing condition was the nozzle pressure 4bar with the 85wt.% of concentration of hydrolyzed protein liquid.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.78-86
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• 2014

Since cellulose nanofibrils (CNF) has large specific surface area and high water holding capacity, it is very difficult task to remove water from the CNF suspension. However, dewatering of CNF suspension is a prerequisite of following processes such as mat forming and drying for the application of CNF. In this study, we evaluated the drainage of cellulose fibers suspension under vacuum and pressure conditions depending on the number of grinding passes. Also, the effect of the addition of cationic polyelectrolyte on dewatering ability of CNF suspension was investigated. Regardless of dewatering condition, the total drained water amount as well as the drainage rate were decreased with an increase in the number of grinding passes. Pressure dewatering equipment enables us to prepare wet CNF mat with relatively higher grammage. The cationic polyelectrolytes improved the dewatering ability of CNF suspension by controlling the zeta potential of CNF. The fast drainage was obtained when CNF suspension had around neutral zeta potential.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.292-298
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• 2005

Tunnel in subway should be designed as a water-proof type tunnel as much as possible but it is difficult to make it come true due to several facts, such as construction technique and cost. A drainage type tunnel as a substitute of a water-proof tunnel lead to the increase of water pressure on the concrete lining that make bad effect to tunnel structure when it has some problem to operate the drainage system. Throughout studying about cases on defects of tunnel drainage in subway We hope it contributes to tunnel maintenance.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2682-2687
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• 2008

Depressurized drainage systems have been used for more than 30 years and are becoming a common part of urban drainage infrastructures. The hydraulic principles governing the operation of the depressurized drainage systems were studied in this paper and particularly, focused on the analysis of unsteady characteristics of the two-phase flow. A definition of the filling ratio was outlined and types of flow pattern were classified according to the filling ratio. Experiments were conducted to investigate the main features of pressure fluctuation. All results were found to depend on the filling ratio of the upstream pipe flow as well as the upstream Froude number.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.435-445
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• 2019

A series of element tests with different drainage conditions and strain rates were performed on compacted unsaturated non-plastic silt in unconfined conditions. Soil samples were compacted at water contents from dry to wet of optimum with the degree of saturation varying from 24 to 59.5% while maintaining the degree of compaction at 80%. The tests performed were shear infiltration tests in which specimens had constant net confining pressure, pore air pressure was kept drained and constant, just before the shear process pore water pressure was increased (and kept constant afterwards) to decrease matric suction and to start water infiltration. In constant water content tests, specimens had constant net confining pressure, pore air pressure was kept drained and constant whereas pore water pressure was kept undrained. As a result, the matric suction varied with increase in axial strain throughout the shearing process. In both cases, maximum shear strength was obtained for specimens prepared on dry side of optimum moisture content. Moreover, the gradient of stress path was not affected under different strain rates whereas the intercept of failure was changed due to the drainage conditions implied in this study.

• Steel and Composite Structures
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• v.51 no.4
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• pp.363-375
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• 2024

Within the optimization field, addressing the intricate posed by fluidic pressure loads on functionally graded structures with frequency-related designs is a kind of complex design challenges. This paper thus introduces an innovative density-based topology optimization strategy for frequency-constraint functionally graded structures incorporating Darcy's law and a drainage term. It ensures consistent treatment of design-dependent fluidic pressure loads to frequency-related structures that dynamically adjust their direction and location throughout the design evolution. The porosity of each finite element, coupled with its drainage term, is intricately linked to its density variable through a Heaviside function, ensuring a seamless transition between solid and void phases. A design-specific pressure field is established by employing Darcy's law, and the associated partial differential equation is solved using finite element analysis. Subsequently, this pressure field is utilized to ascertain consistent nodal loads, enabling an efficient evaluation of load sensitivities through the adjoint-variable method. Moreover, this novel approach incorporates load-dependent structures, frequency constraints, functionally graded material models, and polygonal meshes, expanding its applicability and flexibility to a broader range of engineering scenarios. The proposed methodology's effectiveness and robustness are demonstrated through numerical examples, including fluidic pressure-loaded frequency-constraint structures undergoing small deformations, where compliance is minimized for structures optimized within specified resource constraints.