• Steel and Composite Structures
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• v.39 no.4
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• pp.367-381
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• 2021

Reinforced concrete (RC) columns can be strengthened by direct fastening of steel plates around a column, forming composite actions. This method can increase both the total load bearing area and the concrete confinement stress. To predict the axial load resistance of strengthened RC columns, the equivalent passive confinement stress of the stirrups and the steel jacket should be accurately quantified, which requires the stress in the stirrups and shear force in the connections to be first obtained. In this paper, parameters, i.e., the stress ratio of the stirrups and shear force ratio of steel plate connectors are utilized to quantify the stress of the stirrups and shear force in the connections. A mechanical model for determining the stress ratio of the stirrups and shear force ratio of steel plate connectors is proposed and validated using the experimental results in a previous study. The model is found to be robust. Subsequently, a parametric study is conducted and the optimum stress ratios of the stirrups and the optimum shear force ratios of connectors are proposed for engineering designs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.06a
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• pp.15-32
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• 1999

A relationship between stress and stain is very important to design a die to avoid defects of products during semi-solid forming process. Since the liquid will be of eutectic composition in alloys liquid segregation will result in significant or undesirable situation. The materials used in this experiment are A 357. A390, Al2024 alloys that is fabricated by the electro-magnetic stirring process from Pechiney in France. The compression test was performed by induction heating equipment and MTS. In order to prevent the liquid segregation these measured temperature would be useful to control of strain rate during compression test. The liquid segregation is controlled as change of the strain rate and solid fraction during the compression process, The characteristics of flow between solid and liquid phase considering liquid segregation is examined through the above experiments. In the case of medium and high volume fractions of solid the distribution of strain rate is calculated by using compression test data of semi-solid materials (SSM). The thixoforming experiments with the designed die are carried out successfully. The die filling patterns of SSM for variation of die temperature and pressing force have been investigated. The hardness of the thixoformed scroll products is evaluated in terms of the microstructure for each position.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.154-159
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• 2002

Amorphous FeBSiNb alloy ribbons having bulk glass forming ability and high saturation magnetic flux density were produced by single-roller melt spinning apparatus in the thickness range of 22∼102㎛. With the increase of thickness, the coercive force and squareness ratio decreased, while maximum permeability and AC permeability increased. However electrical resistivity was almost constant. Furthermore refined and complex magnetic domain structure was observed in thicker ribbons owing to the change in internal magnetic anisotropy. For the alloy with the thickness of 81㎛, small coercive force of 24 mOe and high effective permeability of 12,000 at 1㎑ were obtained, those are considered to be better comparing to the conventional soft magnetic amorphous alloys (∼20 ㎛). The good soft magnetic properties of the thick FeBSiNb amorphous alloys were attributed to the decrease in surface pinning effect during wall motion, appearance of perpendicular anisotropy and resulted domain refinement.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.89-92
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• 2003

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging from 10nN to 100nN. At low applied loads, a ridge pattern was formed on the PMMA surface. No wear particles were observed during the pattern-forming mild wear. At high applied loads, severe wear occurred accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the Scratching was closely related with surface deformation of the film.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.24-32
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• 1984

The object of the study is to discuss the effect of magic ink as a surface active substance on the mechanism of chip formation in oblique cutting. The Rehbinder effect has been known as a phenomenon that the mechanical strength reduces when the metal is coated with some surface active substances. In order to interpret these surface effects defined by Rehbinder, the influence on the shear strength of shear plane by coating surface active substances, cutting force by the depth of cut, surface roughness and hardness ratio were observed. The results are as follows: 1. By coating the magic ink on free surface of the forming chip, the effective shear angle increases, and the cuttinbg force and the deformed chip thickness decreases. 2. With the large inclination angle the effective shear angle increases, and the specific cutting force and the friction angle decrease. 3. Cutting of the coated surface improves the surface roughness and the hardness ratio drops, which means another Rehbinder effect.

• Korean Institute of Interior Design Journal
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• v.18 no.5
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• pp.31-39
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• 2009

Today, 'Emotion' has come to stay as a powerful culture code. Though there has been not a few research results based on the recognition of the importance of emotion, the concept of 'Emotion' still differs according not only to researchers but also to the fields. There firstly lies the aim of this study to research the moaning and feature of 'Emotion' through John Dewey's Theory of Experience. Secondly, this study tries to categorize the strata of emotion in space, and further tries to present the methodology for the study of emotion shown in the space. Emotion is the impulse corresponding to the root force drawing out indefinite situations into the context of the problem, and is also the force which integrates all the elements in the process of reflective correlation. Emotion can be referred to as the activating and combining force which makes it possible for the separate elements to be related to the whole as one, and as the feature forming the completion of the transaction between organisms and environment.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.96-102
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• 2006

This paper presents the mechanics of the link of a double-action link-type hydraulic die set for the enclosed die forging. Operational principle of the die set in the enclosed die forging is introduced with emphasis on force transmission from the press and the hydraulic system to the material through links, die components and punches. The force exerted on the link is statically investigated and its structural analysis is carried out. The analyzed results are discussed to be used for design of the link system.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.59-64
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• 2004

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging form 10nN to 100nN. At low loads, a ridge pattern was formed on the PMMA thin film surface. No wear particles were observed during the pattern-forming mild wear. At high loads, severe wear by plowing occurred, accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the scratching was measured, which was closely related with surface deformation of the film. A simple empirical equation to deduce scratch hardness of the film from a linear fixed-distance scratch test was proposed, and scratching-speed dependency of the scratch hardness was displayed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1503-1508
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• 2006

To increase the applicability and productivity of hydroforming process, hydro-embedding process was developed by combining the hydro-forming process with embedding process simultaneously. It is necessary in the automotive parts to form hollow bodies with connection elements which combine one part with another. The hydro-embedding process is embedding the connection element hydraulically during the operating steps of the hydroforming. In this study, technique of rotational piercing is added on the existing hydro-embedding to increase the connection force of hydro-embedded element. To estimate the feasibility of new trial process, integrated researches on the hydro-embedding process technology have been performed by analyzing the deformed mode of the tubes and the optimal process parameters for various shapes of the connection elements.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3286-3288
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• 1999

The electrostatically actuated test structure was presented to measure the micro mechanical characteristics of micromaterials as thin films forming the microactuators. The test structure was fabricated by the surface micromachining processes and driven by the electrostatic force, In order to measure the fracture toughness, the sharp notch in the test structure was introduced by the etching process. On the basis of the beam bending theory, the elastic modulus was measured by using the microcantilevr beam and the mechanical displacement, curvature and deflection curve under the electrostatic force was evaluated by using the electrostatic structure.