• 한국지반환경공학회 논문집
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• 제2권4호
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• pp.63-72
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• 2001

연약지반에 구조물을 시공하는 경우가 빈번해짐에 따라 연약지반 개량의 필요성이 증대하고 있다. Granular pile 공법은 연약한 점성토 지반이나 느슨한 사질토 지반의 개량에 사용되는 연약지반처리공법이다. 국내에서는 모래를 이용한 SCP공법은 종종 사용해 왔지만 쇄석을 이용한 Granular pile은 외국에 비해 그 사용실적이 미비한 실정이다. 그러나 모래자원의 고갈에 따른 환경적, 경제적인 문제때문에 모래 대신 이용할 수 있는 대체재의 필요성이 절실해지고 있다. 본 연구에서는 Granular pile 공법에 의해 개량된 연약한 점성토 지반의 거동 특성을 파악하기 위하여 모형토조를 이용한 하중재하 및 압밀시험을 실시하였다. 또한, Pile 재료로서 모래뿐만 아니라 쇄석을 이용한 실내모형 시험으로 각각의 재료에 따른 지지력 특성 및 침하 특성, 배수 특성 등의 공학적 특성을 비교 평가하여 모래의 대체재로서 쇄석의 활용가능성을 검토하였다. 시험결과, 쇄석은 모래 재료에 비해 지지력증대와 침하저감효과가 크고, 유사한 간극수압특성을 보여 모래의 대체재료로서 쇄석의 활용이 가능하다고 판단된다.

• 펄프종이기술
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• 제44권1호
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• pp.52-57
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• 2012

In this study, we investigated the possible use of a new inorganic material as alternative filler in the paper industry. The inorganic material is a mineral composed of calcium sulfate, that is generated when manufacturing phosphate fertilizer. The inorganic material was dehydrated by the thermal treatment to $200^{\circ}C$, $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$ to prepare white filler powders. Their basic properties, including color, particle shape, elements, and average particle size were identified. To determine the effect of new inorganic filler on paper's physical properties and strength, handsheets were prepared from HwBKP, SwBKP, and thermal treated inorganic fillers. Handsheets' ISO brightness, opacity, bulk, breaking length, and stiffness were measured. Results confirmed that thermal treated inorganic filler could be beneficial to the bulk and opacity of paper while maintaining higher level of breaking length and stiffness that is achieved using talc.

• 한국지반공학회논문집
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• 제18권5호
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• pp.43-54
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• 2002

연약지반에 구조물을 시공하는 경우가 빈번해짐에 따라 연약지반 개량의 필요성이 증대하고 있다. Granular pile 공법은 연약한 점성토 지반이나 느슨한 사질토 지반의 개량에 사용되는 연약지반처리공법이다. 국내에서는 모래를 이용한 SCP공법은 종종 사용해 왔지만 쇄석을 이용한 Granular pile은 외국에 비해 그 사용실적이 미비한 실정이다. 그러나 모래자원의 고갈에 따른 환경적, 경제적 인 문제 때문에 모래 대신 이용할 수 있는 대체재의 필요성이 절실해지고 있다. 본 연구에서는 Granular pile 공법에 의해 개량된 연약한 점성토 지반의 거동 특성을 파악하기 위하여 모형토조를 이용한 하중재하 및 압밀시험을 실시하였다. 또한, Pile 재료로서 모래뿐만 아니라 쇄석을 이용한 실내모형시험으로 각각의 재료에 따른 지지력 특성 및 침하 특성, 배수 특성 등의 공학적 특성을 비교 평가하여 모래의 대체재로서 쇄석의 활용가능성을 검토하였다. 시험결과, 쇄석은 모래 재료에 비해 지지력증대와 침하저감효과가 크고, 유사한 간극수압특성을 보여 모래의 대체재료로서 쇄석의 활용이 가능하다고 판단된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.365-366
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• 2002

The sliding wear behavior of ultra high molecular weight polyethylene (UHMWPE) was examined on a novel low temperature degradation-free zirconia/alumina composite material and conventional alumina and zirconia ceramics used for femoral head in total hip joint replacement. The wear of UHMWPE pins against these ceramic disks was evaluated by performing linear reciprocal sliding and repeat pass rotational sliding tests for one million cycles in bovine serum. The weight loss of polyethylene against the novel low temperature degradation-free zirconia/alumina composite disks was much less than those against conventional ceramics for all tests. The mean weight loss of the polyethylene pins was more io the linear reciprocal sliding test than in the repeal pass rotational sliding lest for all kinds of disk materials. Neither the coherent transfer film nor the surface damage was observed on the surface of the novel zirconia/alumina composite disks during the test. The observed r,'stilts indicated that the wear of the polyethylene was closely related to contacting materials and kinematic motions. In conclusion, the novel zirconia/alumina composite leads the least wear of polyethylene among the tested ceramics and demonstrates the potential as lhe alternative materials for femoral head in total hip joint replacement.

• 한국포장학회지
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• 제12권1호
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• pp.35-40
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• 2006

Cushioning systems, which are cushion material and its designed configuration, are important to protect fragile items since they act as buffers between the impact force and the fragile product. As cushioning materials, several plastic foams are commonly used in industry. However, the utilization of the plastic material has been causing a solid waste problem and pollution. Thus, as an alternative cushion material to the plastic foams, a corrugated cushion, which is considered environmentally friendly and cheap material, was put into drop tests and its impact shock attenuation was investigated. Flat and free drop data were recorded and compared to the dynamic shock of EPS cushion. In addition, the mathematical model of the shock attenuation of the corrugated cushion was developed. The result showed that the corrugated cushion gave an excellent protection for items that were subjected to the limited number of drops. There was no significant difference of the shock absorbing ability between the EPS and corrugated cushions. Energy density model of cushioning material successfully explained the mechanical behavior and fatigue of the corrugated cushions.

• Structural Engineering and Mechanics
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• 제50권6호
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• pp.773-796
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• 2014

This paper deals with free vibration analysis of continuous grading fiber reinforced (CGFR) and bi-directional FG annular sector plates on two-parameter elastic foundations under various boundary conditions, based on the three-dimensional theory of elasticity. The plates with simply supported radial edges and arbitrary boundary conditions on their circular edges are considered. A semi-analytical approach composed of differential quadrature method (DQM) and series solution is adopted to solve the equations of motion. Some new results for the natural frequencies of the plate are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. Results indicate that the non-dimensional natural frequency parameter of a functionally graded fiber volume fraction is larger than that of a discrete laminated and close to that of a 2-layer. It results that the CGFR plate attains natural frequency higher than those of traditional discretely laminated composite ones and this can be a benefit when higher stiffness of the plate is the goal and that is due to the reduction in spatial mismatch of material properties. Moreover, it is shown that a graded ceramic volume fraction in two directions has a higher capability to reduce the natural frequency than conventional one-dimensional functionally graded material. The multidirectional graded material can likely be designed according to the actual requirement and it is a potential alternative to the unidirectional functionally graded material. The new results can be used as benchmark solutions for future researches.

• Earthquakes and Structures
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• 제6권6호
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• pp.627-646
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• 2014

Adobe is one of the oldest construction materials that is still used in many seismic countries, and different construction techniques are found around the world. The adobe material is characterized as a brittle material; it has acceptable compression strength but it has poor performance under tensile and shear loading conditions. Numerical modelling is an alternative approach for studying the nonlinear behaviour of masonry structures such as adobe. The lack of a comprehensive experimental database on the adobe material properties motivated the study developed here. A set of a reference material parameters for the adobe were obtained from a calibration of numerical models based on a quasi-static cyclic in-plane test on full-scale adobe wall representative of the typical Peruvian adobe constructions. The numerical modelling, within the micro and macro modelling approach, lead to a good prediction of the in-plane seismic capacity and of the damage evolution in the adobe wall considered.

• Steel and Composite Structures
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• 제18권4호
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• pp.889-907
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• 2015

This paper aims to present an alternative analytical method for transient vibration analysis of doubly-curved laminated shells subjected to dynamic loads. In the method proposed, the governing differential equations of laminated shell are derived using the dynamic version of the principle of virtual displacements. The governing equations of first order shear deformation laminated shell are obtained by Navier solution procedure. Time-dependent equations are transformed to the Laplace domain and then Laplace parameter dependent equations are solved numerically. The results obtained in the Laplace domain are transformed to the time domain with the help of modified Durbin's numerical inverse Laplace transform method. Verification of the presented method is carried out by comparing the results with those obtained by Newmark method and ANSYS finite element software. Also effects of number of laminates, different material properties and shell geometries are discussed. The numerical results have proved that the presented procedure is a highly accurate and efficient solution method.

• Advances in concrete construction
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• 제6권4호
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• pp.407-422
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• 2018

The study evaluates properties of brick having coal ash and explores the possibility of utilization of coal bottom ash and coal fly ash as an alternative raw material in the production of coal ash bricks. Lower cement content was used in the investigations to attain appropriate strength and prohibit high carbon content that is cause of environmental pollution. The samples use up to 7% of cement whereas sand was replaced with bottom ash. Bricks were tested for compressive strength, modulus of rupture, ultrasonic pulse velocity (UPV), water absorption and durability. The results showed mix proportions of bottom ash, fly ash and cement as 1:1:0.15 i.e., M-15 achieved optimum values. The coal ash bricks were well bonded with mortar and could be feasible alternative to conventional bricks thus can contribute towards sustainable development.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1996년도 추계학술발표회 논문집
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• pp.34-44
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• 1996

N-machine produces more than input energy at above 3000 rpm. any space energy is absorbed when the N-machine is rotating at a very high velocity. Laws of electromagnetics verify that normal conduction is due to that electrons moves from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next. The ${\pi}-far$ infrared rays are generated from the resonance and rotation of the electrons on the orbitals of three-dimensional crystallizing ${\pi}-bonding$ atoms. Material in universe is composed of ${\pi}-rays$, which have alternative outward electric field. If the alternative outward electric fields of the ${\pi}-rays$ are resonant each other they make attraction force, which is the gravity. The collection of space energy is due to a attraction force between the radially alternating electric field and the ${\pi}-far$ infrared rays in the space. Electrons flow by absorbed density difference of ${\pi}-far$ infrared rays along a conduction wire, which also verifies that normal electron conduction is due to a flow from one three-dimensional crystallizing ${\pi}-bonding$ orbital to next.