• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.5
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• pp.93-101
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• 2010

The demand for elastic pavement, providing comfort for pedestrians is expected to increase continuously but the lack of a standard for materials mixing ratio, that is, the optimal mixing ratio between ERDM chip and polyurethane binder, is still in a trial and error stage. This study aimed at recommending an optimal mixing ratio for elastic landscape pavement through a coherence and resilience test depending on ratio. The test result is outlined as follows. In a tensile strength test, samples B and C indicated a close positive relationship between the binder mixing ratio and tensile strength, indicating that the higher the mixing ratio the higher the tensile strength. In a hardness test, none of samples A, B or C indicated a statistical interrelationship between the binder mixing ratio and hardness. That is, the hardness of the elastic pavement material remained unchanged, irrespective of the binder mixing ratio. In a resilience lest, Samples A and B indicated a close negative interrelation between mixing ratio and resilience, indicating that the higher the mixing ratio, the lower the resilience. Upon analyzing the optimal mixing ratio based on test results, an increase in tensile strength began to slow at a 20% mixing ratio, while resilience began to reduce rapidly at 22%, Thus the optimal range for a mixing ration appeared to be 20~22%. The outcome of this study could to provide guidance for improving the elasticity and stability of elastic pavement.

• Korean Journal of Applied Biomechanics
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• v.30 no.4
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• pp.285-291
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• 2020

Objective: Shoes midsole are crucial for reducing impact forces on the lower extremity when someone is running. Previous studies report that the cushioning of running shoes make it possible to use less muscular energies. However, the well cushioned shoes result in energy loss as the shoe midsole is compressed. Cushioning reduces the load on the body, it also results in the use of more muscle energy to create propulsion force. The purpose of this study was to investigate the effect of the difference of shoe hardness & resilience on the running. Method: Shoes midsole are crucial for reducing impact forces on the lower extremity when someone is running. Previous studies report that the cushioning of running shoes make it possible to use less muscular energies. However, the well cushioned shoes result in energy loss as the shoe midsole is compressed. Cushioning reduces the load on the body, it also results in the use of more muscle energy to create propulsion force. The purpose of this study was to investigate the effect of the difference of shoe hardness & resilience on the running. Results: In vastus lateralis muscle Activation, Type 55 were significantly higher for Type 50 and X (p=0.019, p=0.045). In Gluteus Maximus muscle activation, Type 55 was significantly lower for type 50 (p=0.005). In loading late, Type 55 and X were significantly higher for type 45 (p=0.008, p=0.006). Conclusion: The components of a shoe are very complex, and there can be many differences in manufacturing as well. Although some differences can be found in the biomechanical variables of the high elastic midsole, it is difficult to interpret the performance enhancement and injury prevention.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.5021-5028
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• 2015

Previous studies have considered the permeability and construction method of paving materials, thus focusing on more practical issues rather than basic research of their properties. The present study investigated the possibility of using an elastic paving material having lesser thickness in the resurfacing of existing concrete or asphalt paved areas while satisfying the necessary conditions of resilience and water permeability. An alternative to complete reconstruction would reduce the amount of resource wastage and environmental pollution, as well as the cost of projects. This study investigated five variants of thickness (10, 13, 15, 20, 25mm) and three mixing ratios of binder to rubber chips (20, 22.5, 25%) to ascertain the ideal basic properties of each. The obtained test data revealed that a minimum thickness(10~25mm) of the elastic paving materials can be determined from a qualitative point of view, and alternatives should be provided to improve the durability of the paving material on account of the temperature sensitivity.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.737-747
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• 2021

The objective of seismic resilience is to maintain or rapidly restore the function of a building after an earthquake. An efficient tilt mechanism at the member level is crucial for the restoration of the main structure function; however, the damage resistance of the members should be the main focus. In this study, through a comparison with the classical Flamant theory of local loading in the elastic half-space, an elastomechanical solution for the axial-stress distribution of a reinforced-concrete (RC) rocking column was derived. Furthermore, assuming that the lateral displacement of the rocking column is determined by the contact surface rotation angle of the column end and bending and shear deformation of the column body, the load-lateral displacement mechanical model of the RC rocking column was established and validated through a comparison with finite-element simulation results. The axial-compression ratio and column-end strength were analyzed, and the results indicated that on the premise of column damage resistance, simply increasing the axial-compression ratio increases the lateral loading capacity of the column but is ineffective for improving the lateral-displacement capacity. The lateral loading and displacement of the column are significantly improved as the strength of the column end material increases. Therefore, it is feasible to improve the working performance of RC rocking columns via local reinforcement of the column end.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.281-284
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• 2009

Flexible forming process for sheet metal using reconfigurable die is introduced based on numerical simulation. Numerical simulation of sheet metal forming process is carried out by using flexible dies model instead of conventional matched die set. Elastic cushion which has high resilience behavior from excessive deformation are inserted between forming punches and blank material for smoothing the forming surface which has discrete due to characteristics of the flexile die. As an elastic cushion, urethane pads are utilized using hyperelastic material model in the simulation. Formability in view of surface defect such as onset of dimple is compared with regard to various punch sizes. Consequently, it is confirmed that the flexible forming process for sheet material has appropriate capability and feasibility for manufacturing of smoothly curved surface instead of conventional die forming process.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.55-69
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• 2013

An alternative design method of existing methods based on elastic theory the design method of roadbed considering plastic deformation of roadbed and stress-strain at roadbed materials with the cyclic loading of trains passing. The characteristics of the developed design method considering traffic load, number of cyclic loading and resilience modulus of roadbed materials can evaluate elastic strain as well as plastic settlement with allowable design criteria. The proposed design method is applied to standard roadbed section drawing of HONAM high-speed railway considering design conditions such as allowable elastic and plastic settlement, train speed, the tonnage of trains. As a result, required levels of resilience modulus model parameter ($A_E$), unconfined compressive strength, types of soil material were evaluated.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.2
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• pp.355-363
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• 2002

The purpose of this study was to investigate how the weave type, yarn twist fabric count and fiber content of the worsted fabrics affect the subjective sensation of the hand. Thirty worsted fabrics that were mainly used for the spring and fall ladies'suits at national brands were selected. Variables were such as four different kinds of weave types, plain, twill, satin and decorative; two levels of yarn twist, normal and high; various fabric counts; two different fiber contents, pure wool and Lycra contained. Image analysis and wavelet transform techniques were used to quantify the surface fiber, For surface characteristics, MIU, MMD and SMD were measured by KES-FB system. The Questionnaires with 23 adjectives were used for the subjective hand evaluation. Panels were So specialists of fashion or fabric designers and merchandizers. By Factor Analysis, six factors that represent the subjective hand were extracted. The relationship between these factors and structural variables were analyzed. Yarn twist was significantly related to the surface characteristics and resilience. Weave structure affected surface characteristics, volume/warm-cool feeling and resilience. Fabric counts showed relations with volume/warm-cool feeling and the fiber contents with volume/warm-cool feeling, resilience and elastic properties. MIU, MMD and SMD showed no relations with the surface fibers. Subjective sensation of surface characteristics was affected by SMD and surface fibers.

• Earthquakes and Structures
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• v.24 no.6
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• pp.415-428
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• 2023

Low-cost techniques with seismic isolation performance and excellent resilience need to be explored in the case of rural low-rise buildings because of the limited buying power of rural residents. As an inexpensive and eco-friendly isolation bearing, scrap tire pads (STPs) have the issue of poor resilience. Thus, a seismic isolation system under a column (SISC) integrated with STP needs to be designed for the seismic protection of low-rise rural buildings. The SISC, which is based on a simple exterior design, maintains excellent seismic performance, while the mechanical behavior of the internal STP provides elastic resilience. The horizontal behaviors of the SISC are studied through load tests, and its mechanical properties and the intrinsic mechanism of the reset ability are discussed. Results indicate that the average residual displacement ratio was 24.59%, and the reset capability was enhanced. Comparative experimental and finite element analysis results also show that the load-displacement relationship of the SISC was essentially consistent. The dynamic characteristics of isolated and fixed-base buildings were compared by numerical assessment of the response control effects, and the SISC was found to have great seismic isolation performance. SISC can be used as a low-cost base isolation device for rural buildings in developing countries.

• Journal of Aerospace System Engineering
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• v.4 no.2
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• pp.1-9
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• 2010

An airless tire has advantages over the conventional pneumatic tire in terms of flat proof and maintenance free. According to the recently disclosed inventions on the airless tire, non-pneumatic tire (NPT) consists of the flexible polygon spokes. Considering the NPT structure, the spokes undergo the tension-compression cyclic loading while the tire rolls. Therefore the spokes of NPT are required to have both stiffness and resilience under the cyclic tensile-compressible loading. In general, if a material has a high stiffness, it shows a low elastic strain limit. In this paper, using the auxetic honeycomb structure with negative poissons's ratio, the spokes of NPT tire are designed to have both stiffness and resilience. Finite element based numerical simulation of the contact pressure of a NPT is carried out with ABAQUS.

• Polymer(Korea)
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• v.25 no.5
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• pp.679-690
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• 2001

High resilience PU foams were prepared with polyether type cell opener. The influences of cell opener concentration on the kinetics, rheology, structural stability morphology and open cell content of the obtained foam were investigated and the role of cell opener during cell opening was determined. And mechanical properties as a function of cell opener concentration were studied. It was observed that urea formation reaction was delayed due to high hydrophilicity of cell opener The decrease of viscosity and the increase of tan $\delta$ were confirmed with increasing cell opener concentration so that the resulted foam had low structural stability and high open cell content. The deterioration of matrix and uniform dispersion of hydrogen-bonded urea in matrix with cell opener concentration was revealed by SEM analysis. As a result, elastic properties of the foam matrix were decreased due to high hydrophilicity of cell opener during the preparation of high resilience polyurethane foam and foam with high open cell content resulted. Hardness, tensile strength, tear strength, elongation of foam were decreased with increasing cell opener concentration.