꼬리말발도리(Deutzia paniculata Nakai)와 가침박달 (Exochorda serratifolia S.Moore)은 각각 5~6월과 4~5월에 흰색 꽃이 피는 화목관목으로 한국의 희귀식물이며, 관상가치가 높아 원예용으로 개발할 가치가 있다. 본 연구에서는 꼬리말발 도리와 가침박달의 종자를 이용한 번식체계를 확립하고자 플러 그 육묘에서 플러그 트레이의 셀 크기, 배지조성, 시비수준에 따른 유묘의 생육을 조사하였다. 꼬리말발도리는 플러그 트레이 의 셀 크기가 작아질수록 유묘의 생육이 불량하였고, 105구의 셀 크기에서 초장, 엽장과 엽폭, 줄기와 뿌리의 생체중 등 생육 이 가장 양호하였다. 또한 배지의 조성은 피트모스와 펄라이트 를 20:80로 혼합한 처리에서 줄기와 뿌리의 생육이 가장 우수하 였고, 펄라이트 단용인 0:100 처리에서 유묘의 생육이 가장 불 량하였다. 가침박달은 피트모스와 펄라이트를 100:0과 75:25 로 혼합한 배지에서 유묘의 생육이 가장 좋았고, 펄라이트 단 용인 0:100 배지에서 유묘의 줄기뿐만 아니라 뿌리의 생육 도 가장 불량하였다. 그리고, 육묘 기간동안 시비수준이 증가 함에 따라 유묘의 줄기 생육이 양호하였으며, 엽록소의 함량도 증가하였다. 따라서 가침박달은 플러그 트레이 당 Hyponex (N:P:K=20:20:20) 6.24.g을 관주하는 것이 고품질 묘를 생산 하는데 가장 효과적이었다. 따라서 꼬리말발도리는 105공 플러 그 트레이에 피트모스와 펄라이트의 20:80 비율의 배지를 사용 하는 것이, 가침박달은 피트모스와 펄라이트의 100:0과 75:25 비율의 배지에서 육묘기간동안 Hyponex 6.24g를 시비하는 것이 유묘 생육에 가장 적합하였다.
Roller Compacted Concrete Pavement (RCCP) is placed by roller compaction of a mixture of less cement and unit water content and more aggregates and provides excellent early strength development with the help of interlocking of aggregates and hydration. The unit cement content of RCC pavements accounts for 85% of conventional pavements, with low drying shrinkage. As low drying shrinkage leads to smaller crack widths than ordinary concrete, RCC pavements can help elevate reflecting crack resistance if applied to a base layer of a composite pavement system. In a composite pavement with an asphalt surface laid over a concrete base, pavement temperature change is important in predicting pavement performance. As movement of the lower concrete layer is determined by temperature depending on pavement depth, temperature data of the pavement structure serves as an important parameter to prevent and control reflecting crack. Among the causes of reflecting crack, horizontal behavior of the lower concrete layer and curling-caused vertical behavior of joints/cracks are considered closely related to temperature change characteristics of the lower concrete course (Baek, 2010). Previous studies at home and abroad about reflecting crack have focused on pavement behavior depending on daily and yearly in-service temperature changes of a composite pavement (Manuel, 2005). Until now, however, studies have not been conducted on initial temperature characteristics of concrete in composite pavements where asphalt surface is placed over an RCC base. Annual temperature changes of in-service concrete pavements go up to 60 ℃, and those of asphalt overlays become around the twice at 110 ℃. This study evaluated initial crack behavior of composite pavement by investigating pavement temperature by depth of an RCC base and analyzing joint movement depending on change to temperatures of continuously jointed pavements. Findings from the study suggest that in composite pavements and asphalt overlays, time of laying asphalt has an important impact on crack behavior and reflecting crack.
Roller-compacted concrete or RCC is a dry concrete that requires compaction in order to reach its final form. Its consistency is usually overlooked due to its inconsistency and lack of subjective nature. To work with this concrete, however, appropriate consistency is required for supporting the compacting machine and minimizing compaction energy. Due to transportation and compaction time, maintaining proper consistency within a period of time is also necessary. Vebe time, a represent parameter of dry concrete consistency, ranged from 30 to 75 seconds is considered appropriate for RCC in pavement application. The purpose of this study is to improve workability of this concrete which consisted of improving its consistency and maintaining it within the working time. It was confirmed that the workable time of a normal RCC is less than one hour. Moreover, it was found that Vebe time drops when water content increases and goes up when sand by aggregate ratio increases. Various admixtures were also employed in this study in order to improve the workability of this concrete. Poly Naphtalene Sulfonate superplasticizer, particularly, was found to be the most effective in term of lowering down Vebe time and maintaining it. With just 0.3% of this admixture, the working time of RCC can be extended up to four hours without affecting its compressive strength.
More Roller-compacted concrete (RCC) is a dry concrete consisted of same materials as conventional concrete with different proportioning which requires compaction effort in order to reach its final form. Thus, both hydration and aggregate interlock play important roles in its strength augmentation. Flexural strength, an important factor in pavement design and fatigue cracking resistance, can be difficult to be obtained at in-situ and may be subjected to high variability. Even though its compressive strength is relatively high compared to conventional concrete with similar binder content, the relationship between compressive strength and flexural or tensile strength were not well defined. The goal of this research is to compare the relationship between compressive strength and flexural strength as well as the relationship between compressive strength and splitting tensile strength of RCC with those of conventional concrete using various equations suggested in other researches and also to determine new regression equations for estimating RCC’s flexural and splitting tensile strength. The positive result of RCC’s flexural strength was found; it was higher than majority of predicted values from conventional concrete for the same compressive strength. In contrast, RCC’s splitting tensile strength was relatively low compared to that of conventional concrete for the same compressive strength. Power equations were learned to be suitable for relationship between compressive and flexural strengths as well as relationship between compressive and splitting tensile strengths.
Porcine parvovirus (PPV), a member of the genus Parvovirus, family Parvoviridae, is a significant causative agent in porcine reproductive failure, causing serious economic losses in the swine industry. PPV is a non-enveloped virus and its capsid is assembled from three viral proteins (VP1, VP2, and VP3). The major capsid protein, VP2 is the main target for neutralizing antibodies in PPV. When VP2 was expressed in large amounts, it assembled into virus-like particles (VLPs) similar in size and morphology to the original virions. In this study, we generated the recombinant Bombyx mori nucleopolyhedrovirus (BmNPV) to express the VP2 protein. Expression of the VP2 protein was analyzed by SDS-PAGE and Western blot. The recombinant VP2 protein of approximately 64 kDa was detected by both analyses. The formation of VLP by recombinant VP2 was confirmed through transmission electron microscopy examination. The purified VP2 protein assembled into spherical particles with diameters ranging from 20 to 22 nm.
The bulb mite (Rhizoglyphus echinopus) damages garlic, shallot and onion in the bulbs, corms and tubers. It has recently become a serious problem because of the continuous use of acaricides resulting in resistance among bulb mite population. Thus, there is need to find alternative control measures to suppress bulb mite population. Here, we report the screening result of pathogenic fungi for the control of R. echinopus. Initial screenings were performed using 352 isolates of entomopathogenic fungi from Korea soils. As results, 15 isolates of acaropathogenic fungi showed the pathogenicity to bulb mite supporting fungal conidiation. These isolates were identified as 3 isolates of Metarhizium flavoviride var. pemphigi and 12 isolates of Metarhizium pingshaense by microscopic examination and genetic sequencing of the ITS region and elongation factor-1 alpha. Selected 15 isolates were tested for their virulence against adult R. echinopus and the thermotolerance and the activity to UV-B irradiation of conidia. Additionally, the activities of chitinases and proteases produced by M. pingshaense were compared according to the medium. These acaropathogenic fungi would be considered promising for biological control of bulb mite.