There are many types of foam molding methods. The most commonly used methods are the pressure foaming method, in which foam resin is mixed with a foaming agent at high temperature and high pressure, and the normal pressure foaming method, which foams at high temperature without pressure. The polymer resins used for foaming have different viscosities. For foaming under normal pressure, they need to be designed and analyzed for optimal foaming conditions, to obtain resins with low melt-viscosity or a narrow optimal viscosity range. This study investigated how changes in viscosity, molding temperature, and cross-link foaming conditions affected the characteristics of the molded foam, prepared by blending rubber polymer with biodegradable resin. The morphologies of cross sections and the cell structures of the normal pressure foam were investigated by SEM analysis. Properties were also studied according to cross-link/foaming conditions and torque. Also, the correlation between foaming characteristics was studied by analyzing tensile strength and elongation, which are mechanical properties of foaming composites.

Roller-compacted concrete (RCC) has been widely used for construction of pavements [1]. The strength of RCCP can be obtained from not only hydration of binder but also the aggregate interlock resulted from roller-compaction [2]. For this reason, RCCP normally achieves higher strength compared to conventional concrete pavement with similar cement content. Even though RCCP can be provided a good structural performance, it has been difficult to verify the long-term performance though actual field construction. Therefore, this study aimed to investigate the fatigue characteristics and crack development in RCCP based on full-scale fatigue test and accelerated pavement test. In case of full-scale fatigue tests, fatigue behavior was evaluated by using 1 m × 1 m dimensional RCC slab specimens obtained from the field in order to consider the field variability. Fatigue equation derived from this study shows that the number of load repetitions which causes fatigue failure at the same stress level is slightly larger than that of PCA fatigue equation. In order to evaluate the performance of RCCP, two phases of accelerated pavement test (APT) were conducted. In phase one, the performance of RCCP at two different strengths (35.6 and 30.4 MPa) was evaluated. In phase two, the performance of RCCP with different thickness (5, 7.5 and 10 cm) was investigated. The number of load repetition of fatigue crack occurrence in each section was compared to the estimated fatigue failure determined from fatigue equation of RCCP. The crack development in each section was compared to the AASHTO crack model for JPCP. Overall, it was confirmed that RCCP has equal or better performance compared to JPCP the estimation in term of fatigue cracking. The fatigue equation from PCA and cracking model from AAHTO can be used on RCCP at certain design thickness range.

Freshwater green algae are one of the important sources of bioenergy in the future. Spirogyra is a conjugating filamentous zygnematacean green algal genus that is widely distributed worldwide with more than 400 species. Despite its widespread occurrence throughout the world, cytological studies of the genus have been limited. We investigated karyological features and chromosome numbers for seven Korean Spirogyra species. Most of the species examined in the present study showed significant karyological features, inner organization of nucleolus, heavily stainable nucleolar substance and the diffuse-centric nature of chromosomes, typical of the Conjugales. Chromosome number ranged from n=12 in S. varians to n=38 in S. africana. Aberrant cytokinesis resulted in binucleate and tetranucleate cells, which sometimes provide cytological explanation for different morphology and ploidal changes in clonal culture of Spirogyra or even different cells within the same filament. The present chromosome data also substantiates the earlier held assumption that aneuploidy must have been the chief driving force for speciation and evolution of the genus Spirogyra.

본 연구는 단체종목과 개인종목 운동선수의 Ego-gram을 파악하고 단체종목과 개인종목의 운동선수 구분에 가장 큰 영향을 미치는 자아상태를 알아보고자 하였다. 이를 위하여 대학팀의 종목별 운동선수 총 240명을 표본으로 선정하였다. 빈도분석결과 단체종목, 개인종목 운동선수 모두 FC와 AC가 가장 높게 나타났으며, 단체종목 운동선수들의 FC와 AC가 개인종목 운동선수에 비해 높게 나타났다. 판별분석을 통하여 다섯 가지 자아상태(비판적 어버이자아: CP, 양육적 어버이자아: NP, 어른 자아: A, 자유스런 어린이자아: FC, 순응적 어린이자아: AC) 가운데 NP와 A가 단체종목과 개인종목의 운동선수 구분에 가장 큰 영향을 미치는 자아상태로 나타났으며, NP의 경우 단체종목 운동선수가 개인종목 운동선수보다 높게, A의 경우 개인종목 운동선수가 단체종목 운동선수보다 높게 나타났다.

Danok3, a sweet corn hybrid that matures early was developed by the corn breeding team at the National Crop Experiment Station (NCES), RDA in 2001. Inbred KSS2 derived from Golden Bantam was used as the seed parent of Danok3, and inbred KSS22 derived from