• 생명과학회지
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• 제28권1호
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• pp.99-104
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• 2018

Streptococcus pneumoniae는 pneumolysin과 같은 병원성 인자를 가지고 있으며, 지역사회에서 전파되는 심각한 병원성균에 포함된다. Pneumolysin (PLY)은 콜레스테롤 의존적으로 세포막에 구멍을 형성하는 세포독소로서 백신의 주요한 표적 항원이다. PLY의 연구를 위하여 Streptococcus pneumoniae D39 균주에서 추출한 genomic DNA를 주형으로 하여 PCR을 시행하였다. 합성된 PLY 유전자 DNA를 pQE-30 vector에 삽입하고, E. coli M15에 형질전환 시킨 후 LB 배지에 IPTG를 첨가하여 PLY 단백질을 생산하였다. 재조합 단백질은 $Ni^{2+}$-agarose column을 사용하여 정제하였다. 또한, EGFP를 PLY C-말단에 부착한 융합단백질도 동일한 방법으로 클로닝하여 재조합 단백질을 생산하였다. 500 ng/ml 농도의 재조합 PLY는 1.0% 적혈구 현탁액을 100% 용혈시켰으며, 240 ng/ml 농도는 50% 용혈을 나타내었다. 그러나 재조합 PLY-EGFP는 용혈 활성이 전혀 나타나지 않았으나 형광현미경으로 관찰하였을 때 적혈구 막에 결합되어 있었다. 즉, EGFP의 PLY C-말단 부착은 PLY의 세포막 결합능은 유지시켰으나 용혈기능은 방해하였다. PLY C-말단은 용혈기능에 아주 중요한 영역이며, 세포막 결합은 PLY의 다른 영역이 보다 중요하게 작용할 것으로 추측된다. 따라서, 육안으로 관찰이 가능한 결합능은 가졌으나 용혈 기능이 결여된 PLY-EGFP를 대조군으로 활용함으로써 두 재조합 단백질은 폐렴 유발에 있어서 PLY 작용 연구에 사용될 수 있을 것으로 기대된다.

• Journal of Biosystems Engineering
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• 제12권4호
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• pp.9-15
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• 1987

The vibrational characteristics of a radial-ply (155SR13 4PR) and a biased-ply tire (6.15-134PR) were investigated for examining the effects of tires with different structure on the ride characteristics of the vehicle. The natural frequencies at the tread band, mode shapes, and damping factors of two tires at the state of plane vibration were determined experimentally. The test work was performed at four levels of the inflation pressure, ranging from 171.7 kPa to 245.2 kPa, and three levels of the vertical load, deviating by 10% from the standard load designated by the Department of Transportation of the United States of America. The following results were drawn by the analysis of the test results: 1. The first-order natural frequencies of the radial-ply and the biased-ply tires at the tread band were 112 Hz and 159 Hz, respectively, at the state o f the free vibration when the inflation pressure of 196.2 kPa was applied. It was known that the biased-ply tire has higher resonant frequency than the radial-ply tire and the natural frequencies of the both tires move to the high frequency range as t he inflation pressure is increased. 2. The vibration modes of both tires were quite different. No big difference in mode shapes was examined as the inflation pressure was increased. But the natural frequencies of two tires were changed. For the radial-ply tire, no difference in mode shape was found whether the vertical load was applied or not. But a significant difference in mode shape was examined for the biased-ply tire. 3. Any difference was not found in damping factor as the different inflation pressures were applied. 4. When no vertical load was applied, damping factors of the radial-ply and biased-ply tire at the state of the natural vibration ranged from 2.6 to 5.9%, and from 4.1 to 7.8%, respectively. It was estimated that the radial-ply tire would have better cushioning than the biased-ply tire since the vertical spring rate of the radial-ply tire was much less than that of the biased-ply tire, even though the damping effect of the radial-ply tire was smaller than that of the biased-ply tire.

• Journal of the Korean Wood Science and Technology
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• 제22권3호
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• pp.17-25
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• 1994

This study was carried out to compare the properties of Com-Ply Boards with those of OSBs. These two kinds of boards were made of same flakes. Com-Ply Boards were covered with three different thickness veneers, such as 4mm, 3mm, and 2.5mm. All manufactured Com-Ply Boards and OSBs were 12mm thick. In MOR, all Com-Ply Boards were higher than OSB, and especially 3mm-veneer and 2.5mm-veneer Com-Ply Board were highest. But OSB showed 420kg/$cm^2$. 3mm-veneer Com-Ply Board showed the highest internal bonding 7.0kg/$cm^2$ and then 2.5mm-veneer showed 6.8kg/$cm^2$, and OSB showed 6.6kg/$cm^2$. Screw holding strength showed the high value 23.9kg/$cm^2$, 25.5kg/$cm^2$, and 29.3kg/$cm^2$ respectively at 3mm-veneer, 2.5mm-veneer Com-Ply Board and OSB. Thickness swelling of Com-Ply Boards was lower than that of OSB, but Water absorption of OSB was lower. Finally it was very encouraging that all properties of OSB without veneer, whose cost is higher than flake and whose properties is better, were not worse than those of Com-Ply Board with veneer. It seems That more researches on OSB will be required.

• 한국산림과학회지
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• 제96권1호
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• pp.54-57
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• 2007

요소수지접착제를 합판제조용 접착제와 유사하게 실험실에서 합성하고, 합성한 요소수지접착제를 증량제, 충전제, 산경화촉매제와 혼합하였다. 요소수지접착제 혼합물의 고형분량은 56.1%이고, 물은 43.9%였다. 국산재와 요소수지접착제 혼합물로 5종류의 Com-Ply를 제조하고, KS F 3101 보통합판의 인장 전단 접착력 시험 및 KS F 3104 파티클보드의 휨파괴계수 시험을 수행했다. 성능 평가된 결과는 제조된 5종류의 Com-Ply에서 모두 적합한 결과를 보여줬다. 이런 결과는 본 연구에서 사용된 요소수지접착제 혼합물이 국산재 Com-Ply제조에 적합하다는 것이다.

• Steel and Composite Structures
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• 제32권4호
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• pp.423-441
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• 2019

This study aims to accurately predict the first ply failure loads of laminated composite hypar shell roofs with different boundary conditions. The geometrically nonlinear finite element method (FEM) is used to analyse different symmetric and anti-symmetric, cross and angle ply shells. The first ply failure loads are obtained through different well-established failure criteria including Puck's criterion along with the serviceability criterion of deflection. The close agreement of the published and present results for different validation problems proves the correctness of the finite element model used in the present study. The effects of edge conditions on first ply failure behavior are discussed critically from practical engineering point of view. Factor of safety values and failure zones are also reported to suggest design and non-destructive monitoring guidelines to practicing engineers. Apart from these, the present study indicates the rank wise relative performances of different shell options. The study establishes that the angle ply laminates in general perform better than the cross ply ones. Among the stacking sequences considered here, three layered symmetric angle ply laminates offer the highest first ply failure load. The probable failure zones on the different shell surfaces, identified in this paper, are the areas where non-destructive health monitoring may be restricted to. The contributions made through this paper are expected to serve as important design aids to engineers engaged in composite hypar shell design and construction.

• Journal of the Korean Wood Science and Technology
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• 제20권3호
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• pp.29-37
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• 1992

This research was carried out to investigate the effects of cyclic humidification on the dimensional stability of particleboard manufactured according the three specific gravity levels and com-ply fabricated with a core of particleboard and veneer or plywood as the face and back materials. Both the particleboard and com-ply were subjected to four cycles of 50-90-50% relative humidity. The results are summarized as follows: Particleboard and com-ply followed a clear pattern of increasing dimensions and weight on the adsorption cycle and decreasing dimensions and weight on the humidification cycle. After the fourth cycle, the dimensions and weight of both particleboard and com-ply were greater than those originally measured. The greater part of increase in occurred during the first humidification cycle. The specific gravity of particleboard has a significant effect thickness and volume change. The dimensional stability of com-ply was better than that of particleboard. In addition, the dimensional stability of com-ply bonded with plywood was better than that of com-ply bonded with veneer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.641-644
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• 2005

The aim of this research is to evaluate the relationship between the total effective moment $(M^E)$ and Bemoulli-Euler bending moment (M) when the ply orientations of UD CFRP in Piezoelectric Zirconate Titanate Composite Actuator (PZTCA) are changed. The obtained results as follows. Firstly, as the performance test results by the CFRP ply orientation, the performance of [0] and [90] were stable. However, while the performance of [+45] was suddenly decreased after 5 hours. Secondly, the change of $M^E$ by the CFRP ply orientation was evaluated. As the CFRP ply orientation was increased from [0] to [+60], the $M^E$ were gradually decreased. However, they became a little bit increased from [+60] to [90]. Finally, after the change of M by the CFRP ply orientation was evaluated, it was found that $M^E=2.2M$ was valid for just [0] and that there was a relationship between $M^E$ and M according to the ply orientation.

• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.791-806
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• 2020

본 연구에서는 공학목재로 목구조건축에 주로 사용되는 집성재 및 CLT 그리고 Ply-lam CLT의 블록전단시험을 실시하여 강도 및 파괴 유형을 비교 분석하였다. 이를 통해 Ply-lam CLT의 라미나 및 합판의 수종, 접착제의 종류 및 Layer구성 등 최적생산을 위한 제조조건을 구명하고자 하였으며 그 결과는 다음과 같다. 블록전단시험을 통해 집성재, Ply-lam CLT, CLT 순으로 높은 강도를 나타냈다. 특히, 낙엽송 합판과 낙엽송 라미나의 복합구조로 제조되는 Ply-lam CLT의 전단강도는 집성재 전단강도 기준인 7.1 N/㎟을 통과하였다. 아울러 본 연구에서는 집성재, CLT, Ply-lam 접착에 사용된 접착제 종류에 따른 전단강도의 차이는 나타나지 않았다. 그러나 Ply-lam CLT의 경우에는 라미나와 합판의 수종에 따라 Ply-lam CLT의 전단강도의 차이를 나타냈다. 그 결과는 낙엽송 > 남양재 ≒ 육송 합판 순으로 높은 강도를 나타났다. Ply-lam CLT의 최적 구성은 낙엽송 합판과 낙엽송 라미나를 사용하는 경우이며 접착제는 용도에 따라 PRF, PUR을 선정하여 사용하면 될 것으로 판단된다. 목질재료 유형에 따른 전단강도 파괴 양상 결과 분석을 통하여 집성재는 shear parallel-to-grain, CLT는 rolling shear, Ply-lam CLT는 shear parallel-to-grain과 rolling shear가 복합적으로 나타났다. 이는 전단강도 결과와 밀접한 관련이 있으며 rolling shear로 인하여 CLT보다 Ply-lam CLT에서 더 높은 전단 강도를 나타내는 것으로 판단된다.

• 대한기계학회논문집A
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• 제26권5호
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• pp.960-968
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• 2002

In this research, the effects of fiber stacking sequence on damage behaviors of FML(Fiber Metal Laminates) subject to indentation loading. SOP (Singly Oriented Ply) FML and angle ply FML were fabricated to study fiber orientation effects and angle ply effects. FML were fabricated by using 1050 aluminum laminate and carbon/epoxy prepreg. To increase adhesive bonding strength, Al laminate was etched using FPL methods. The static indentation test were conducted by using UTM under the 2side clamped conditions. During the tests, load and displacement curve and crack initiation and propagation behaviors were investigated. As fiber orientation angle increases, the crack initiation load of SOP FML increases because the stiffness induced by fiber orientation is increased. The penetration load of SOP FML is influenced by the deformation tendency and boundary conditions. However, the macro-crack of angle ply FML was initiated by fiber breakage of lower ply because angle plies in Angle ply FML prevents the crack growth and consolidation. The Angle ply FML has a critical cross-angle which prevent crack growth and consolidation. Damage behavior of Angle ply FML is changed around the critical cross-angle.

• 대한기계학회논문집A
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• 제30권3호
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• pp.318-327
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• 2006

Due to the diversified use of recent Piezoelectric Zirconate Titanate Composite Actuate. (PZTCA), various PZTCAs with the different ply orientation of the fiber layer have been applied. For this reason, the applicable bending moment equation is necessary even though the fiber layer ply orientation and the laminate configuration are changed. The aim of this research is to evaluate the relationship between the total effective moment $(M^E)$ and Bernoulli-Euler bending moment (M) when the ply orientations of UD CFRP are changed. In conclusions, firstly, as the performance test results by the CFRP ply orientation, the performance of [0] and [90] were stable. However, while the performance of [+45] was suddenly decreased after 5 hours. Secondly, the change of $(M^E)$ by the CFRP ply orientation was evaluated. As the CFRP ply orientation was increased from [0] to [+60], the $(M^E)$ were gradually decreased. However, they became a little bit increased from [+60] to [90]. Finally, after the change of M by the CFRP ply orientation was evaluated, it was found that $M^E=2.2M$ was valid for just [0] and that there was a relationship between $M^E$ and M according to the ply orientation.