• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.613-625
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• 2016

Contact interaction of a beam (flexible element) with an elastic half-plane is considered, when a soft inhomogeneous (functionally graded) interlayer is present between them. The beam is bent under the action of a distributed load applied to the surface and a reaction of the elastic interlayer and the half-space. Solution of the contact problem is obtained for different values of thickness and parameters of inhomogeneity of the layer. The interlayer is assumed to be significantly softer than the underlying half-plane; case of 100 times difference in Young's moduli is considered as an example. The influence of the interlayer thickness and gradient of elastic properties on the distribution of the contact stresses under the beam is studied.

• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.12-16
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• 2021

Attempts are being made to provide various tactile feedbacks to user. In particular, a variety of soft actuators are being inserted into the tactile feedback device to give a more flexible, soft and strong stimulation. In this study, a basic study was performed to utilize a hydraulically amplified self-healing electrostatic (HASEL) actuator as a tactile feedback actuator. The HASEL actuator showed great displacement and force with a simple circuit configuration. In particular, by making the actuator in a circular shape, the angle was reduced and the electrode was arranged in a ring shape to maximize the displacement of the central part. As a result, the HASEL actuator showed a displacement difference according to the input waveform. In addition, in order to use it safely as an actuator for tactile feedback, we covered the surface with silicone and confirmed that the actuator works well. Using these actuators, it will be possible to manufacture a lightweight, portable tactile feedback device.

• Journal of Urban Science
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• v.9 no.2
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• pp.51-56
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• 2020

The installation of soft ground instruments and the performance of measurement and management of the measurement shall be carried out in order to ensure the safety of the construction work and to improve the quality of the construction work. The purpose of the pressure density deposition calculation is to determine the stability of the foundation ground and the formulation by measuring and calculating the density conditions generated on the soil through the period of neglect after completion of the soil at each stage. In practice, it is judged that the analysis by the hyperbolic method can be applied to the safety side.

• Molecules and Cells
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• v.45 no.2
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• pp.76-83
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• 2022

Neurons-on-a-Chip technology has been developed to provide diverse in vitro neuro-tools to study neuritogenesis, synaptogensis, axon guidance, and network dynamics. The two core enabling technologies are soft-lithography and microelectrode array technology. Soft lithography technology made it possible to fabricate microstamps and microfluidic channel devices with a simple replica molding method in a biological laboratory and innovatively reduced the turn-around time from assay design to chip fabrication, facilitating various experimental designs. To control nerve cell behaviors at the single cell level via chemical cues, surface biofunctionalization methods and micropatterning techniques were developed. Microelectrode chip technology, which provides a functional readout by measuring the electrophysiological signals from individual neurons, has become a popular platform to investigate neural information processing in networks. Due to these key advances, it is possible to study the relationship between the network structure and functions, and they have opened a new era of neurobiology and will become standard tools in the near future.

• Journal of The Geomorphological Association of Korea
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• v.28 no.1
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• pp.1-12
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• 2021

This study tried to reveal relative surface denudation resistance and ranking by geologic types in the Southern Korean Peninsula using an 1:250,000 digital geologic map and ASTER GDEM. Among rock types such as igneous, sedimentary and metamorphic rocks, metamorphic rock showed the greatest resistance to surface denudation. The most resistant rock to surface denudation by geologic periods (e.g., the Precambrian, Paleozoic, Mesozoic and Cenozoic) was found from the Precambrian. Among the major tectonic settings in the Southern Korean Peninsula such as the Gyeonggi massif, Okcheon belt, Yeongnam massif, Gyeongsang basin and Pohang basin, the Okcheon belt indicated the greatest resistance. The most and least resistant rocks from the representative nine rocks in the Southern Korean Peninsula were Paleozoic limestone, and Cretaceous sedimentary rock and Cenozoic sedimentary rock, respectively. This study suggests that Paleozoic limestone, Cretaceous volcanic rock, Paleozoic sedimentary rock and Precambrian gneiss can be regarded as hard rocks with high elevation, steep slope and complicated relief, while soft rocks with low elevation, gentle slope and simple relief are Jurassic granite, Cretaceous sedimentary rock and Cenozoic sedimentary rock.

• Journal of Korean Society of Forest Science
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• v.107 no.3
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• pp.287-293
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• 2018

This study was carried out to provide surface bearing capacity reinforcement of forest road by sub-base facilities based on a soft ground use of geosynthetics to prevent the damage of the road surface passing heavy logging trucks and to pass smoothly heavy truck against growing timber harvesting. The analysis of the road surface bearing capacity as progressing time and the increase of the number of passage of heavy logging trucks were conducted experimental section of forest road on the soft ground in the Forest Technology and Management Research Center. As a result, it was found that the road surface bearing capacity were stabilized at CBR of 15% or more, the effect of reinforcement by type of geosynthetics showed no significant difference after the lapse of about 1 year. After reaching the passage of 300 times for the heavy logging trucks on the sub-base construction section, the settlements was stabilized below the allowable standard of 50 mm, road surface bearing capacity also improved to more than CBR 20% and there was no significant difference in the thickness of the sub-base. However, in the section where the sub-base is not constructed, it is found that the lack of surface bearing capacity with the settlements more than the allowable standard is not possible to pass the heavy logging trucks. Therefore, in order to reinforce the road surface bearing capacity of the soft ground for the passage of the heavy logging trucks, it is necessary to construct a sub-base of at least 0.2 m when using geosynthetics.

• Journal of the Korean Magnetics Society
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• v.25 no.1
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• pp.4-9
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• 2015

This study was carried out to investigate a influence of humidity variation (%) on the magnetic properties and the surface flaws in the fabrication of Fe-based $Fe_{78}Si_9B_{13}$ amorphous alloy ribbon by Planar Flow Casting process. As a result, the size of the air pocket and the droplet which is observed in the contact surface and the free face of the amorphous alloy ribbon becomes large when the humidity increases and the size highly increases with the surface roughness at the same time. Especially, the surface roughness value which is made in the 65 % of the humidity is the lowest in the contact surface ($Ra=0.60{\mu}m$, $Rz=3.11{\mu}m$) and the free face ($Ra=0.47{\mu}m$, $Rz=3.00{\mu}m$). Also, in case of the soft magnetic property of the magnetic core which is made with the toroidal core of $23(OD)^*20(ID)^*20(H)$ size, in the sample of the amorphous alloy ribbon which is made in 65% of the humidity, the most excellent value is gained as $B_s(B_{700})=1.055T$, $H_c=0.083Oe$, permeability = 1,197 and core loss = 0.276W/kg.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.75-84
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• 2020

This paper described the analysis result on heaving of soft ground with DCM column type, based on the results of laboratory model tests on the soft ground with DCM column. The heave characteristics of the soft ground were evaluated according to the application of DCM column in soft ground. The results showed that the heaving of soft ground without DCM column occurred rapidly when the lateral deformation of soft ground increased significantly under the 4th load step condition. In addition, the heaving of soft ground in final load step caused tensile failure of the ground surface. The maximum heaving of the soft ground with the DCM column occurred in the final load step, and the heaving quantity decreased in the order of pile, wall, and grid type. Especially, the soft ground with DCM of grid type effectively resisted ground heaving, even if it was extremely failure in the bottom ground of embankment. The results of the maximum heaving according to the measurement point showed that the heaving of the soft ground with DCM of grid type was 3.1% and 1.6% compared to that of the pile and wall type at the location of LVDT-1, and the heaving of the LVDT-2 position was 1.0% and 2.1%, respectively.

• Journal of the Korea Furniture Society
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• v.17 no.1
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• pp.83-89
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• 2006

Because the surface of pine wood is very soft, there have been many attempts, like as surface coating, resin impregnation, and densificationt, to harden the surface of wood for its interior use. This study was carried out for surface hardening of pine wood by laminating of melamine resin sheet. The effect of laminating method on the characteristics of melamine resin sheet-laminated wood(MLW) was investigated. Flat-sawn softwoods were suitable for MLW making. And the pre-drying of wood at $105^{\circ}C$ for 30min, before laminating, was effective for preparing of defect-free MLW. The abrasion resistance of pine wood was greatly improved by laminating of melamine resin sheet on its surface. Consequently, the laminating of melamine resin sheet was proved to be a favorable method for improvement of surface abrasiveness of pine wood.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.586-590
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• 2006

As one of electro active polymers for soft smart materials, the ionic polymer metal composites (IPMC) are easy to produce through chemical reduction processing and show high displacements at low voltage. When the IPMC actuates, the deformation depends on a few factors including the structure of based membrane, species and morphology of the metal electrodes, the nature of cations and the level of hydration. As previously published, we have been studying on improvement of actuation through surface electrode modification of IPMC to grasp the effect of electrode morphology on actuation. This study is comparative experiments through the chemical reaction and deposition by ion beam assisted deposition (IBAD) in order to prepare the very thin and homogeneous surface electrode of IPMC. The IPMCs were prepared with different surface roughness of polymer membrane, and the influence of the surface roughness on the actuation was studied. By investigating the electrical properties and driving displacement, the actuating properties of IPMC with different surface roughness were studied.