• Structural Engineering and Mechanics
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• 제67권6호
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• pp.617-628
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• 2018

This paper deals with the maximization of the critical buckling load of simply supported antisymmetric angle-ply plates resting on Pasternak foundation subjected to compressive loads using teaching learning based optimization method (TLBO). The first order shear deformation theory is used to obtain governing equations of the laminated plate. In the present optimization problem, the objective function is to maximize the buckling load factor and the design variables are the fibre orientation angles in the layers. Computer programming is developed in the MATLAB environment to estimate optimum stacking sequences of laminated plates. A comparison also has been performed between the TLBO, genetic algorithm (GA) and differential evolution algorithm (DE). Some examples are solved to show the applicability and usefulness of the TLBO for maximizing the buckling load of the plate via finding optimum stacking sequences of the plate. Additionally, the influences of different number of layers, plate aspect ratios, foundation parameters and load ratios on the optimal solutions are investigated.

• Structural Engineering and Mechanics
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• 제3권2호
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• pp.121-133
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• 1995

It is well known that two-dimensional simplified third-order theories satisfy the layer interface continuity of transverse shear strains, thus these theories violate the continuity of transverse shear stresses when two consecutive layers differ either in fibre orientation or material. The third-order theories considered herein involve four/or five dependent unknowns in the displacement field and satisfy the condition of vanishing of transverse shear stresses at the bounding planes of the plate. The objective of this investigation is to examine (i) the flexural response prediction accuracy of these third-order theories compared to exact elasticity solution (ii) the effect of layer interface continuity conditions on the flexural response. To investigate the effect of layer interface continuity conditions, three-dimensional elasticity solutions are developed by enforcing the continuity of different combinations of transverse stresses and/or strains at the layer interfaces. Three dimensional twenty node solid finite element (having three translational displacements as degrees of freedom) without the imposition of any of the conditions on the transverse stresses and strains is also employed for the flexural analysis of the laminated plates for the purposes of comparison with the above theories. These shear deformation theories and elasticity approaches in terms of accuracy, adequacy and applicability are examined through extensive numerical examples.

• Journal of Ginseng Research
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• 제8권2호
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• pp.91-104
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• 1984

This study was conducted to investigate the characteristics of nonstarchy polysaccharides in Korean ginseng, (Panax ginseng C.A. Meyer). The results obtained are as follows. 1. The total sugar content of ginseng roots were decreased with increasing the cultural period. On the other hand, the crude fiber content was increased with that of the ginseng leaves or stems. But the crude fiber in root was much less than that of leaves and stems. 2. The dietary fiber content of ginseng root on 5 years old was 14.20% as neutral detergent fiber, 9.08% as acid detergent fiber, hemicellulose 5.12%, cellulose 7.98% and lignin of 1.10%, respectively. 3. Much more pectin was found in ginseng roots which was cultivated for shooter Period. And it was contained much more in the root than in the leaves and stems. 4. ginseng hemicellulose content in root was 5% to 10%. It was decreased with increasing: cultivated period. Hemicellulose was constituted of xylose, arabinose, glucose, rhamnose and xylose of these sugars was the predominant. 5. X-ray diffraction Pattern of ginseng cellulose showed maximum intensity at tile interplanar angle of 4.1$^{\circ}$.

• 국제초고층학회논문집
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• 제7권4호
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• pp.397-408
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• 2018

In a recent tragic fire incident, the Plasco Tower collapsed after an intense outburst of fire lasting for three and a half hours and claiming the lives of 16 firefighters and 6 civilians. This paper will present continuing collaborative work between Hong Kong Polytechnic University and Queen's University in Canada to model the progressive collapse of the tower. The fire started at the 10th floor and was observed to have travelled along the floor horizontally and through the staircase and windows vertically. Plasco Tower was steel structure and all the steel sections were fabricated by welding standard European channel or angle profiles and no fire protection was applied. Four internal columns carried the loads transferred by the primary beams, and box columns were constructed along the perimeter of the building as a braced tube for resisting seismic loading. OpenSees fibre-based sections and displacement-based beam-column elements are used to model the frames, while shell elements are used for the reinforced concrete floor slabs. The thermal properties and elevated temperature mechanical properties are as recommended in the Eurocodes. The results in this preliminarily analysis are based on rough estimations of the structure's configuration. The ongoing work looks at modeling the Plasco Tower based on the most accurate findings from reviewing many photographs and collected data.

• Applied Microscopy
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• 제16권2호
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• pp.1-13
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• 1986

The purpose of this study was to investigate the morphology and intercellular junctions of the odontoblast of dental pulp in the rat incisor by means of the freeze fracture electron microscopy. Twenty male Sprague-Dawley rats weighing $150{\sim}200g$ were used. After being anesthetized by an intraperitoneal injection of 0.5 ml sodium pentobarbital per kg in body weight(60 mg/ml) the animals were perfused with 2.5% glutaraldehyde-2% paraformaldehyde fixative in 0.1 M cacodylate buffer, pH 7.2 through the ascending aorta for one hour. The incisors were carefully extracted from the jaws and demineralized by suspending them in 0.1 M EDTA in 3% glutaraldehyde (pH 7.2) for two weeks. After demineralization, the specimens were obtained from the portion divided into five equal parts. For freeze-fracture replication, demineralized tissues were infiltrated for several hours with 10%, 25% glycerol in 0.1M cacodylate buffer as a cryoprotectant and then frozen in liquid Freon 22 and stored in liquid nitrogen. Fracturing and replication were done in Balzers BAF 400D high-vacuum freeze-fracture apparatus at $-120^{\circ}C$ under routine $5X10^{-7}$ Torr vacuum. The tissue was immediately replicated with platinum unidirectionally at $45^{\circ}$ angle and reinforced with carbon at $90^{\circ}$ angle unidirectionally or by using a rotary stage. The replication process was monitored by a quartz-crystal device. The replicas were immersed in 100% methanol overnight. The tissue was then digested from the replica by clorox (laundry bleach), placed into 5% EDTA, and washed repeatedly with distilled water. The replicas were picked up on 0.3% formvar-coated 75 mesh grids and examined in the JEOL 100B electron microscope. The results were as follows; 1. Both in thin sections and freeze-fracture replicas, three types of intercellular junctions were recognizable in the plasma membrane of odontoblast: gap junction, tight junction and desmosome-like junction. 2. The nuclear pores were evenly distributed over the nuclear envelope. The pore complex formed a ring about 70 nm in diameter. 3. Gap junctions were found between odontoblasts as well as odontoblasts and neighbouring pulp cells (fibroblast, subodontoblastic cell process, nerve-like fibre). Gap junctions, which were round, ellipsoid and pear-shaped and 600 nm in diameter, were observed in the odontoblast. 4. Numerous round and ellipsoid gap junctions could be frequently seen on the plasma membranes in cell body and apical part of the odontoblasts. On the P face, the junctions were recognized as a cluster of closely packed particles, measuring about 9 nm in diameter, and on the E face, the junctions were recognized as a shallow grooves.

• 한국수산과학회지
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• 제9권1호
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• pp.13-18
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• 1976

주름을을 준 상태의 매듭그물강의 매듭의 강도를 조사하기 위해, 길이가 70cm 되는 2개의 그물실로 매듭을 만들고 인정한 2재의 다리가 이루는 각 $\varphi$를 $O^0$(매듭의 세로방향)로 부터 $180^{\circ}$(매듭의 가로방향)까지 변화시켜, 12개의 점에서 그 강도를 측정했다. 또한, $45^{\circ}$의 $\varphi$에 전개해 있는 다리중 어떤 1개의 다리를 각 $\varphi(0^{\circ}\~30^{\circ})$로 들어 올려 4개의 점에서 그 강도를 측정했다. 그물실의 재료는 mono-filament, multi-filament 및 spun 그물실로 구분하여 10종류를 사용했다. 실험의 결과, $\varphi$가 증가함에 따라서 바른매듭의 강도는 거의 직선적으로 감소하고 막매듭의 강도는 거의 직선적으로 증가했다. $\varphi$가 $100^{\circ}$이하에서는 바른매듭이 막매듭보다 강하고, $100^{\circ}$이상에서는 그 반대였다. $\varphi'$가 증가할수록 매듭의 강도는 지수함수적으로 감소했다. 이들 $\varphi,\varphi'$에 의한 매듭강도의 변화는 전보에서 제시한 매듭강도의 식에 의한 변화경향과 거의 일치하는 것 같았다.