• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.22-28
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• 1998

This paper presents experimental investigations on the attenuation characteristics of pressure ripple in automotive power steering hydraulic hoses. Also, a mathematical model of hydraulic hoses is proposed to support design of the power steering hydraulic circuit and analyze the attenuation characteristics of pressure ripples. The experimental results show that the pulsation attenuation characteristics of hydraulic hoses is remarkably affected by the flexible metal tube inserted coaxially inside a hydraulic hose with a finite length as well as viscoelastic properties of hose wall. It is also shown that the predicted results by the model proposed here agree well with the measured results over a wied range of frequency.

• Bulletin of the Society of Naval Architects of Korea
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• v.52 no.2
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• pp.19-24
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• 2015

A reliable assessment and analysis of the condition of high pressure and temperature steam pipelines requires defining stress state, which will take into consideration not just the impact of internal pressure and temperature but all applied loads. For that, usage of modeling and numerical methods for calculation and analysis of stress state is essential. The main aim of piping stress analysis is to check the design of piping layout, which will allow simple, efficient and economical piping supports and provide flexibility to the piping system for loads and stresses. The piping stress analysis is carried out using CAESER II software. By using this software we can evaluate stresses, stress ratios, flange condition, support loads, element forces and displacements at each node and points. In this paper, only the maximum and minimum displacement results are tabulated, which is also shown in detail by an example of main steam pipelines of UST Main Engine System [1].

• The Korean Journal of Physiology
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• v.11 no.1
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• pp.21-26
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• 1977

Many cases have been reported that a post spinal headache can be relieved immediately by an epidural injection of saline; and autologous blood also has recently been used successfully instead of saline. The changes of the cerebrospinal fluid pressure in 40 cases were observed in the present study in support of the concept; that a continuous leakage in association with hypovolemia and hypotension of the cerebrospinal fluid is the primary cause of a post spinal headache. Subarachnoid pressure increased immediately with saline injection into the lumber epidural space. A spinal needle was inserted into the subarachnoid space at the level of $L2{\sim}3$ and opening pressure of the cerebrospinal fluid was read. An epidural Tuohy needle was insertad at the$L3{\sim}4$ and 25m1 of saline was injected into the epidural space and the cerebrospinal fluid pressure was read in the sitting position. $\underline{Sitting\;Position:}$ Mean pressure after injection $555{\pm}(110.9)mm\;H_2O$, Pressure rise rise (%) 51.3%, Mean opening pressure $366{\pm}(52.2)mm\;H_{2}O$, $\underline{Lateral\;position:}$ Mean pressure after injection $308{\pm}(70.8)mm\;H_{2}O$, Pressure(%) 86.7%, Mean opening pressure $165{\pm}(42.6)mm\;H_{2}O$. These pressure changes responded almost simultaneously as saline was injected. This pressure rise of 51.3% in the sitting position and 86.7% in the lateral position are clinically very significant. Therefore, it is most possible that the immediate relieve of post, spinal headache by injection of fluid into the epidural space is simultaneous with the increase of the cerebrospinal fluid pressure.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.755-767
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• 2018

This paper uses a finite element based approach to provide a comprehensive understanding to the behaviour and the design performance of buried uPVC pipes with different diameters. It also investigates pipes with good and poor haunch support and proposes minimum safe wall thicknesses for these pipes. The results for pipes with good haunch support showed that the maximum pipe wall stress and deformation increase as the diameter increased. The results for pipes with poor haunch support showed an increase in the dependency of the developed vertical displacement on the haunch support as the diameter or the backfill height increased. Additionally, poor haunch support was found to increase the soil pressure, with the effect increasing as the diameter increased. The design of uPVC pipes for both poor and good haunch support was found to be governed by critical buckling. A key outcome is a new design chart for the minimum wall thickness, which enables the robust and economic design of buried uPVC pipes. Importantly, the methodology adopted in this study can also be applied to the design of flexible pipes manufactured from other materials, buried under different conditions and subjected to different loading arrangements.

• Journal of Venture Innovation
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• v.7 no.2
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• pp.19-40
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• 2024

This study was conducted to empirically analyze the impact of environmental factors on small and medium-sized enterprises' intention to adopt digital transformation. A research model was derived for empirical analysis. Environmental factors were subdivided into independent variables, including industrial competitive pressure, labor shortage, government support, and lack of financial resources, with CEO's perception serving as a moderating variable. A survey targeted executives and employees of small and medium-sized enterprises, and 240 valid responses were selected for analysis. The structural equation method using Amos 24 was employed for the empirical analysis. The findings indicated that industrial competitive pressure and government support had a significant positive influence on the intention to adopt digital transformation, while lack of financial resources had a significant negative effect. The significance of labor shortage was not tested. The order of influence on the intention to adopt was government support, industrial competitive pressure, and lack of financial resources. In terms of the impact of industrial competitive pressure and lack of financial resources on the intention of small and medium enterprises to adopt digital transformation, it was found that in groups with low CEO perception, the lack of financial resources had a negative effect. On the other hand, in the case of the group with high perception, industrial competitive pressure was found to have a significant positive effect. These research results were academically meaningful as they produced significant findings by focusing on environmental factors among the various factors that affect the digital transformation of small and medium-sized enterprises. Practically, it can be said that the importance of the role of top management in small and medium-sized enterprises was emphasized anew

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.17-30
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• 2012

A new trenchless tunneling method using pressurizing support has been developed. As it overcomes shortcomings of conventional methods, it is applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies the pressure corresponding to the magnitude of the relaxed earth pressure caused by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through several ways such as numerical tests and various model tests. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long road tunnel that passes under Yeongdong Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months. It decreases the construction period to 35% compared to that of conventional methods, and ground displacement was almost negligible.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.397-419
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• 2012

The pressurizing support tunneling method has been developed that overcomes shortcomings of conventional trenchless methods and applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies higher pressure than the pressure relaxed by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through 3D numerical analyses. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long ramp tunnel that passes under ${\bigcirc}{\bigcirc}$ Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months which decreases construction time to 35% compared to conventional methods, and ground displacement was almost negligible.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.27-36
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• 2005

The performance of innovative prestressed support (IPS) earth retention system applied in urban excavation was presented and investigated. The IPS wales provide a high flexural stiffness to resist the bending by lateral earth pressure, and the IPS wales transfer lateral earth pressure to Corner struts. The IPS wale provides a larger spacing of support, economical benefit, construction easiness, good performance, and safety control. In order to investigate applicability and stability of the IPS earth retention system, the IPS system was instrumented and was monitored during construction. The IPS system applied in urban excavation functioned successfully. The results of the field instrumentation were presented. The measured performances of the IPS earth retention system were investigated and discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.957-967
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• 2017

Firing test of the fuel grain for solid fuel ramjet with additives and ignition support material was conducted. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Boron particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. An oxidant gas having a controlled temperature, pressure and oxygen composition close to the air condition in the ramjet combustor was supplied using the Ethanol blended $H_2O_2$ gas generator. Gas was set to flow at a mass flow rate of 150 g/s and mass flux of $200kg/m^2s$ in the grain port. Through the test, ignition support operated well and ignition delay of 0.5. During the test, stable chamber pressure with 8 bar and high combustion efficiency of 0.86 was confirmed.

• The Journal of Korean Physical Therapy
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• v.19 no.5
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• pp.11-19
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• 2007

Purpose: The purpose of this study was to examine effect of trunk control using pelvic movements upon the foot pressure in patients with hemiplegia. Methods: Twelve males with hemiplegia were the procedure executed turnk control using pelvic movements. The foot pressure were measured using Parotec-system. Results: The data were analysed with paired t-test. First, there was a significant increase in external and internal sensors of dynamic foot pressure change of the hindfoot before and after therapy. Also there was significant increase in hallux (p<0.05). Second, there was a significant increase of affected side in support phase(p<0.05) and decreased of affected side in overlapping phase(p<0.05). Third, there was a significant increase in foot floor contact time and impulse pressure rate between affected and non affected side(p<0.05). Conclusion: The trunk control with pelvic movement had an significant effect on the legs by increase activities of hip flexors and abductors. Also had an effect on ankle dorsiflexion and plantar flexor by biomechanical movement.