• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.111-122
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• 2009

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

• Composites Research
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• v.20 no.3
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• pp.1-7
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• 2007

Manufacturing process of the shear thickening fluid(STF) and evaluation of the ballistic penetration resistance performance of the Kevlar-STF composites were studied. STF was made from silica and ethylene glycol, and the Kevlar-STF composite was made by impregnating the STF into the Kevlar fabric. Specimens including neat Kevlar woven fabrics and Kevlar-STF composites with two types of silica were prepared and carried out the ballistic tests. From the results STFs represented shear thickening behavior irrespective of the silica type, and Kevlar-STF composite with spherical silica showed best ballistic penetration resistance performance among them. Especially the specimens of Kevlar-STF composites with spherical silica showed radial fiber deformation by the projectile during the tests, that was somewhat different deformation behavior from those of the neat Kevlar fabrics shown fiber pull-out phenomena or fracture.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.4
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• pp.99-107
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• 1997

A mixed type finite element method is applied to the nonuniform shear warping beam theory which is very useful for the structural analysis of thin-walled sectional beams considering the shear deformation. As known generally, it is shown that the mixed type finite element method, compared with the displacement type one, can give more balanced accuracy of results in calculating the stresses and displacements of the structure. In this paper, one typical example, the flexural-torsional problem of a discontinuously variable sectional beam under coupled end torsional moments, is selected and analyzed to validate the usefulness of the developed beam element.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.378-385
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• 2012

Vent mixer can provide main flow directly into a recirculation region downstream of the mixer to enhance fuel-air mixing efficiency. Based on experimental results of three-dimensional velocity, vorticity and turbulent kinetic energy obtained by a stereoscopic PIV method, the performance of the vent mixer was compared with that of the step mixer which was used as a basic model. Thick shear layers of the vent mixer induced the increase of the penetration height. The turbulent kinetic energy mainly distributed along a boundary layer between the main flow and the jet plume. This turbulent field activates mass transfer in a mixing region, leading to the mixing enhancement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.35-44
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• 1993

The objective of this study is aimed at developing a new class of polymer concrete, in which hydration of cement and curing of a thermosetting resin can take place simultaneously during the mixing of concrete components. For the selected mix-proportion of the new polymer, the physical and mechanical properties needed for designs are presented. These important properties are compressive strength, flexural strength, split tensile strength, direct strength, fatigue characteristics and fracture parameters. The observed properties are always compared with conventional concrete to serve as reference for engineer in deciding or selecting the proper materials for their projects, and shore protecting structure.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.19-25
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• 2009

The current study developed light-weighted mixed soil that can solve problems related with soft soil such as ground subsidence, sliding and lateral displacement of ground. By reducing weight of reclaimed soil through mixing phosphogypsum and recycled EPS beads with the weathered granite soil. A series of geotechnical laboratory tests including physical index test, compaction test, CBR test, and direct shear test were performed and engineering properties were reviewed in order to assess applicability of the light-weighted mixed soil for roads and abutment and various back-filling materials at the reclamation area. Based on the laboratory test results, it was found that the maximum dry unit weight of the light-weighted soil ranges $14.32{\sim}15.79kN/m^3$ and the optimum water content ranges 21.91~24.23%, which means there is 11~19.3% weight decrease effect when comparing with general weathered granite soil. Also it was found that the corrected CBR value ranges 10.4~18.4% satisfying the domestic regulations on road subgrade and back-filling material. In addition, as for shear strength parameter, cohesion ranges 10.79~18.64 kPa and internal frictional angle ranges $35.4{\sim}37.2^{\circ}$, which are similar with those of general construction soil and back-filling material used in Korea. So it can be concluded that light-weighted mixed soil with phosphogypsum can be used effectively for soft reclamation ground as actual filling material and back-filling material. From the current study, it was found that light-weighted mixed soil with phosphogypsum has not only weight reduction effect, but also has no special problems in shear strength and bearing capacity. Therefore, it is expected that phosphogypsum can be recycled in bulk as road subgrade and back-filling material at the reclamation area.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2006.05a
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• pp.142-145
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• 2006

본 연구는 도축 후 24시간 냉각된 지육에서 등심 부위를 채취하여 $5{\times}15{\times}5cm$ 크기로 잘라 양념액과 육을 1:1로 혼합하여 $1{\pm}1^{\circ}C$에서 28일간 숙성시키면서 저장성을 분석한 결과는 다음과 같다. pH는 T1이 다른 처리구에 비해 월등히 낮은 pH를 나타내었으며 저장기간에 따른 pH의 변화는 나타나지 않았다. 전단가는 T2와 T3는 전 숙성기간 동안 전단가가 감소한 반면 T1은 숙성기간이 증가함에 따라 전단가는 증가하였고 보수력은 T1이 숙성 1일부터 낮은 보수력을 나타내었으며, 모든 처리구에서 숙성기간에 따라 보수력이 다소 감소하였다. 근원섬유 소편화지수는 숙성 1일 다소 낮게 나타났던 T3구가 숙성 기간이 증가하면서 높은 값을 나타낸 반면 T1은 전 숙성기간 동안 다른 처리구에 비해 가장 낮은 소편화도를 나타내었다.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.05a
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• pp.183-186
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• 2005

본 연구는 도축 후 24시간 냉각된 지육에서 등심부위를 채취하여 $5{\times}\;15{\times}\;5cm$ 크기로 잘라 양념액과 육을 1:1로 혼합하여 $1{\pm}\;1^{\circ}C$에서 28일간 숙성시키면서 저장성을 분석한 결과는 다음과 같다. pH는 T1이 다른 처리구에 비해 월등히 낮은 pH를 나타내었으며 저장기간에 따른 pH의 변화는 나타나지 않았다. 전단가는 T2와 T3는 전 숙성기간 동안 전단가가 감소한 반면 T1은 숙성기간이 증가함에 따라 전단가는 증가하였고 보수력은 T1이 숙성 1일부터 낮은 보수력을 나타내었으며, 모든 처리구에서 숙성기간에 따라 보수력이 다소 감소하였다. 근원섬유소편화지수는 숙성 1일 다소 낮게 나타났던 T3구가 숙성 기간이 증가하면서 높은 값을 나타낸 반면 T1은 전 숙성기간 동안 다른 처리구에 비해 가장 낮은 소편화도를 나타내었다.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.91-100
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• 2007

In most design codes, soils are classified as either sand or clay, and appropriate design equations are used to represent their behavior. For example, the behavior of sandy soils is expressed in terms of the relative density, whereas consistency limits are often used for clays. However, sand-clay mixtures, which are typically referred to as intermediate soils, cannot be easily categorized as either sand or clay and therefore a unified interpretation of how the soil will behave at the transition point, i.e., from sandy behavior when fines are low to clay behavior for high fines content, is necessary. In this study, active natural clays are mixed with sand, and the fines content varied in order to produce different structures, ranging from one state where only sand particles form the soil structure to another where the matrix of fines make-up the structure. While paying attention to the granular void ratio in order to clarify the shear properties of sand-clay mixtures with increasing fines content monotonic, shear tests were performed on isotropically, and anisotropically consolidated specimens. From the test results, it was observed that the monotonic shear strength of sand-clay mixtures is dependent on the granular void ratio.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.15-24
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• 2021

In Korea, which is mostly mountainous, the proportion of tunnel and underground space development are increasing. Although the ground is reinforced by applying the ground improvement method during underground space development, accidents still occur frequently in Korea. In the grouting method, a representative ground reinforcement method, the effect was judged by comparing the total amount of injection material with the amount of injection material used during the actual grouting construction. However, it is difficult to determine whether the ground reinforcement is properly performed during construction or within the target ground. In order to solve this problem, it is necessary to study a new method for quality control during or after construction by measuring electrical resistivity after performing grouting by mixing carbon fiber, which is a conductive material, and microcement, which is a grout material. In this study, as a basic study, a cement specimen mix ed with 0%, 3%, 5%, 7% of carbon fiber was prepared to evaluate the performance of the grout material mixed with carbon fiber, which is a conductive material. The prepared specimens were wet curing for 3 days, 7 days, and 28 days under 99% humidity, and then compression wave velocity and shear wave velocity were measured. As a result of the compression wave velocity and shear wave velocity measurement, it showed a tendency to increase with the increase in the compounding ratio of carbon fibers and the number of days of age, and it was confirmed that the elastic modulus and shear modulus, which are the stiffness of the material, also increased.