• Transactions of Materials Processing
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• v.7 no.1
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• pp.66-71
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• 1998

The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the bonding conditions as well as the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding the normal pressure and the contact surface expansion are selected as process parameters governing the bonding conditions, in this study the critical normal pressure required for the local extrusion-the protrusion of virgin surfaces by the surface expansion at the interface-is obtained using a slip line method and is then used as a criteron for the bonding. A rigid plastic finite element method is used to analyze the steady state extrusion process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-cent to interface surface. The contact surface area ration and the normal pressure along the interface are calculated and compared to the critical normal pressure to check bonding. It is found that the model predictions are generally in good agreement with the experimental observations. The compar-isons of the extrusion pressure and interface profile by the finite element with those by experi-ments are also given.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.164-171
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• 2005

This study aims to examine an effect of stacking sequence and curvature on the penetration characteristic of a composite laminated shell. For the purpose, we manufactured specimens with different stacking sequences and curvatures, and conducted a penetration test using an air-gun. To examine an influence according to stacking sequence, as flat plate and curvature specimen had more plies, their critical penetration energy was higher, Critical penetration energies of specimen A and C with less interfaces somewhat higher than those of B and D with more interfaces. The reason that with less interfaces, critical penetration energy was higher is pre-impact bending stiffness of composite laminated shell with less interfaces was lower than that of laminated shell with more interfaces, but bending stiffness after impact was higher. And it is because interface, the weakest part of the composite laminated shell, was influenced by transverse impact. As curvature increases, critical penetration energy increases linearly. It is because as curvature increases, resistance to in-plane deformation as well as bending deformation increases, which need higher critical penetration energy. Patterns of cracks caused by penetration of composite laminated shells include interlaminar crack, intralaminar crack, and laminar fracture. A 0$^{\circ}$ply laminar had a matrix crack, a 90$^{\circ}$ply laminar had intralaminar crack and laminar fracture, and interface between 0$^{\circ}$and 90$^{\circ}$laminar had a interlaminar crack. We examined crack length and delamination area through a penetration test. For the specimen A and C with 2 interface, the longest circumferential direction crack length and largest delamination area were observed on the first interface from the impact point. For the specimen B and D with 4 interface, the longest crack length and largest delamination area were observed on the third interface from the impact point.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1791-1794
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• 2006

For system-on-glass (SoG) with low-temperature poly-silicon (LTPS) thin film transistor (TFT), a new system interface architecture and timing controller are developed. With the newly developed system interface architecture, line memory can be eliminated which would take large area of SoG display panel. The system interface and timing controller are targeted for the application for 6-bit gray scale, 60-frames/s qVGA format.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.105-108
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• 2004

In general, the nonlinear behavior of composite structures composing of steel and concrete is analyzed on the basis of the assumption of the perfect bond actions in steel-concrete interface in which the interface slip or separation is not allowed. The assumption is based on the fact that the full interface bond behavior is provided with the mechanical connectors of studs. However, since the number and spacing of the studs are determined by the stress resultants calculated in the interface area, the interface analysis is required to evaluate the stress resultants. This paper describes the nonlinear steel-concrete interface behavior considering the two interface failure mechanisms of slip and separation. Elastoplastic constitutive relation is developed. thru the formulation framework using the two energy dissipation mechanisms. As the result, the steel plate push-out tests sandwitched between concrete blocks are analyzed and compared with the test results with which the good agreements are observed.

• Tribology and Lubricants
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• v.39 no.1
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• pp.8-12
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• 2023

This study presents a molecular simulation of adhesion control between carbon nanotube (CNT) and Ag thin film deposited on silicon substrate. Rough and flat Ag thin film models were prepared to investigate the effect of surface roughness on adhesion force. Heat treatment was applied to the models to modify the adhesion characteristics of the Ag/CNT interface based on thermal wetting. Simulation results showed that the heat treatment altered the Ag thin film morphology by thermal wetting, causing an increase in contact area of Ag/CNT interface and the adhesion force for both the flat and rough models changed. Despite the increase in contact area, the adhesion force of flat Ag/CNT interface decreased after the heat treatment because of plastic deformation of the Ag thin film. The result suggests that internal stress of the CNT induced by the substrate deformation contributes in reduction of adhesion. Contrarily, heat treatment to the rough model increases adhesion force because of the expanded contact area. The contact area is speculated to be more influential to the adhesion force rather than the internal stress of the CNT on the rough Ag thin film, because the CNT on the rough model contains internal stress regardless of the heat treatment. Therefore, as demonstrated by simulation results, the heat treatment can prevent delamination or wear of CNT coating on a rough metallic substrate by thermal wetting phenomena.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.606-613
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• 2004

One of the major forces that causes landslide is the amount of underground water resulted from rainfall and shear strength. As a result of close study on the landslide area affected by typoon Rusa it is observed that many landslides took place at the interface of rock and soil. Based on this observation that shear strength at the interface played a great role in landslide of the hilly area, two shear strengths were measured on different places, one at the interface between rocks and soil and the other just on soil. The two values thus derived were compared and used to review the safety factor for the hilly areas already collapsed. Back analysis was also used to calculate the ground water table according to the different rock types at the time when degradation happened.

• Polymer(Korea)
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• v.24 no.1
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• pp.23-28
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• 2000

Autoadhesion strength of PS/PS Interfaces in solvent welding was determined as a function of processing conditions by butt joint test. It was verified that the chain mobility and surface roughness at PS/PS interface were enhanced by the applied solvent having a similar solubility parameter as PS and resulted in the dramatic improvement of autoadhesion strength at PS/PS interface. It was found that the mechanism of solvent welding is dependent upon the chain mobility due to the diffusion of solvent to PS interface and the contact area at interface. When the welding temperature is lower than the boiling point of applied solvent, the effect of chain mobility on autoadhesion strength was dominated, while contact area took more important role when welding temperature is above the boiling point of solvent. Autoadhesion strength increased with increasing contact time and contact temperature but :he effect of solvent on autoadhesion strength became smaller.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.719-726
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• 1997

This research was conducted to analyze the change of surface tension, viscosity, streaming current and conductivity of transformer oil when it were injected with the interface active substances.(anionic:S-111, cationic:S-121, amphoteric:S-131) The changes properties of the surface tension and viscosity of the oil which were injected with the interface active substances were divided into the changes area and the minimum reduction area. The surface tension and viscosity of the oil which were injected with three different kinds of interface active substances showed remarkable change at the point where the concentration of the substance in anionic, in cationic and in amphoteric were 100[ppm], 10[ppm] and 1[ppm] respectively. The streaming current and conductivity of the same sample oil were also changed at the same densities of the surface tension and viscosity. For this factor, it was possibile for us to interpret the mechanism of the streaming current and conductivity. Therefore the interface active substances of the three kinds were injected into the oil within the limit of optimal volume, prevention effects of electrification were showed more excellence than unmixed insulating oil.

• Journal of Korean Academy of Nursing
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• v.47 no.6
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• pp.794-805
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• 2017

Purpose: Interface pressure is a factor that contributes to the occurrence of pressure injuries. This study aimed to investigate interface pressure at common sites of pressure injury (occipital, gluteal and peritrochanteric areas), to explore the relationships among risk factors, skin condition and interface pressure, and to identify risk factors influencing interface pressure. Methods: A total of 100 patients admitted to the intensive care unit were enrolled at a tertiary teaching hospital in Korea. Interface pressure was recorded by a scanning aid device (PalmQ). Patient data regarding age, pulmonary disease, Braden Scale score, body mass index, serum albumin, hemoglobin, mean blood pressure, body temperature, and oxygen saturation were included as risk factors. Data collected from July to September 2016 were analyzed using binary logistic regression. Results: The mean interface pressure of the occipital, gluteal, and right and left peritrochanteric areas were 37.96 (${\pm}14.90$), 41.15 (${\pm}16.04$), 53.44(${\pm}24.67$), and 54.33 (${\pm}22.80$) mmHg, respectively. Predictive factors for pressure injuries in the occipital area were age ${\geq}70$ years (OR 3.45, 95% confidence interval [CI]: 1.19~9.98), serum albumin deficit (OR 2.88, 95% CI: 1.00~8.26) and body temperature ${\geq}36.5^{\circ}C$ (OR 3.12, 95% CI: 1.17~8.17); age ${\geq}70$ years (OR 2.81, 95% CI: 1.10~7.15) in the right peritrochanteric area; and body temperature ${\geq}36.5^{\circ}C$ (OR 2.86, 95% CI: 1.17~6.98) in the left peritrochanteric area. Conclusion: Our findings suggest that old age, hypoalbuminemia, and high body temperature may be contributory factors to increasing interface pressure; therefore, careful assessment and nursing care of these patients are needed to prevent pressure injury. Further studies are needed to establish cutoff values of interface pressure for patients with pressure ulcers.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.131-136
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• 2003

Landslide is a natural disaster frequently noticed In korea during monsoon season in flicting nationwise damages on human lives, properties, transportation networks, construction sites, etc. This study is about landslide characteristic in rainfall. This study selects seven sites that occured in 2001 and 2002. So elect areas divide and studied special quality by carcinoma by igneous rock, metamorphic rock, sedimentary rock. According to study finding, because igneous rock area is very thin into 1m interior and exterior soil layer, failures happened much rock and soil interface. There was place that depth of soil layer becomes about 2∼3m being area that receive serious weathering case of metamorphic rock. Therefore, at collapse much debriflow occurrence expect. Case that sedimentary rock area is broken through stratification looked. When see such results, it may become many helps to study characteristics of landslide occurrence area grasping collapse special quality by rock type.