• Animal Systematics, Evolution and Diversity
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• 제26권1호
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• pp.79-82
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• 2010

new species Iotrochota rutzleri n. sp. (Demospongiae: Poecilosclerida: Iotrochotidae) was collected from intertidal zone, Sinyangri, Seongsanpo, Jejudo Island, Korea during 2008-2009. Iotrochota rutzleri n. sp. is similar to I. baculifera Ridley, 1884 in composition of spicules and skeletal structure. However, it is different in size of spicules, growth form and colour. All spicules of this new species are smaller than those of the latter.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.257-259
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• 2007

For this study, SM45C steel rods using generally for power transmission shafts and machine components was selected and welded by Butt-GMAW method. and then it was studied about estimation of fatigue strength and the region of infinite life. From this result, it is demanded that the stress for safety design of machine components using SM45C butt-welded steel rods must be selected in the region of the lowest infinite life of heat affected zone.

• Fisheries and Aquatic Sciences
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• 제8권1호
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• pp.34-38
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• 2005

An alpheid shrimp, Alpheus pacificus Dana, 1852, is recorded from Korea for the first time based on the specimens collected from the intertidal zone in Jeju-do, Korea. A. pacificus is readily distinguished from A. malabaricus by having the inferior shoulder on the lateral face of the major chela with a very deep, rounded notch, and by the simple, non-spatulate dactylus of the third pereopod. The Korean Alpheidae now includes 19 species representing 7 genera.

• 한국해양공학회지
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• 제11권2호
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• pp.57-69
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• 1997

The objetive of this study is to compare the mechanical proprties of 6000 series Al-Mg-Si aluminum alloy (AC120) with 5000 series Al-Mg aluminum alloy (TG25), and to investigate the influence of corrosion solution for fatigue life. Comparing of TG25 and AC120 alloy sheets, TG25 alloy sheets showing higher plastic ratio and total elongation have better formability than AC120 alloy sheets. The hardness of nugget area was a little higher than that of base metal area. Also, grain coarsening was observed in HAZ(Heat Affected Zone). In a corrosion fatigue experiment, the fatigue life decreased as concentration increased, when a dipping time was constant. The life decreased as dippling time increased, when a concentration was constant.

• 한국환경생태학회지
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• 제29권5호
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• pp.729-735
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• 2015

본 연구는 학암포 사질조간대에 서식하는 대형저서동물의 군집구조와 분포양상의 특징을 분석하기 위하여 실시하였다. 조사 정점의 퇴적물 평균입도는 $1.90{\phi}{\sim}2.52{\phi}$의 범위로 평균 $2.37{\phi}$으로 나타나 전체 정점에서 전형적인 사질조간대의 중립사 퇴적상을 나타냈다. 유기물 함량은 0.90%~1.46%의 범위로 평균 1.15%이며, 대부분의 정점에서 사질조간대에서 나타나는 낮은 유기물 함량 수치가 나타났다. 전체 조사 정점에서 6개의 분류군 총 59종, 출현 개체수는 $668inds./m^2$이었다. 조사지역의 10개 정점에서 Bray-Curtis index의 유사도(Similarity)를 분석한 결과, 크게 3개의 그룹으로 나뉘었는데, 조간대 상부지역인 St. 2~St. 4, 조간대 중부지역인 St. 5~St. 8, 조간대 하부지역인 St. 9~St. 10으로 이루어졌다. 또한, 상 중 하부로 나누어지는 공간적인 군집구조 양상이 나타났다.

• Molecules and Cells
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• 제20권2호
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• pp.210-218
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• 2005

The rice genome contains at least 28 EXPA (${\alpha}$-expansin) genes. We have obtained near full-length cDNAs from the previously uncharacterized genes. Analysis of these newly identified clones together with the 12 identified earlier showed that the EXPA genes contain up to two introns and encode proteins of 240 to 291 amino acid residues. The EXPA proteins contain three conserved motifs: eight cysteine residues at the N-terminus, four tryptophan residues at the C-terminus, and a histidine-phenylalanine-aspartate motif in the central region. EXPA proteins could be divided into six groups based on their sequence similarity. Most were strongly induced in two-day-old seedlings and in the roots of one-week-old plants. However, only 14 genes were expressed in the aboveground organs, and their patterns were quite diverse. Transcript levels of EXPA7, 14, 15, 18, 21, and 29 were greater in stems, while EXPA2, 4, 5, 6, and 16 were highly expressed in both stem and sheath but not in leaf blade. EXPA1 is leaf blade-preferential, and EXP9 is leaf sheath-preferential. Most of the root-expressed genes were more strongly expressed in the dividing zone. However, the Group 2 EXPA genes were also strongly expressed in both mature and dividing zones, while EXPA9 was preferentially expressed in the elongation zone. Fourteen EXPA genes were expressed in developing panicles, with some being expressed during most developmental stages, others only as the panicles matured. These diverse expression patterns of EXPA genes suggest that in general they have distinct roles in plant growth and development.

• Structural Engineering and Mechanics
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• 제17권1호
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• pp.51-68
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• 2004

Since the linear elastic fracture analysis has been proved to be insufficient in predicting the failure of strain hardening materials, a number of fracture concepts have been studied which remain applicable in the presence of plasticity near a crack tip. This work thereby presents a new finite element model to predict the elastic-plastic crack-tip field and fatigue life of center-cracked panels(CCP) with ductile fracture under large-scale yielding conditions. Also, this study has been carried out to investigate the path-dependence of J-integral within the plastic zone for elastic-perfectly plastic, bilinear elastic-plastic, and nonlinear elastic-plastic materials. Based on the incremental theory of plasticity, the p-version finite element is employed to account for the accurate values of J-integral, the most dominant fracture parameter, and the shape of plastic zone near a crack tip by using the J-integral method. To predict the fatigue life, the conventional Paris law has been modified by substituting the range of J-value denoted by ${\Delta}J$ for ${\Delta}K$. The experimental fatigue test is conducted with five CCP specimens to validate the accuracy of the proposed model. It is noted that the relationship between the crack length a and ${\Delta}K$ in LEFM analysis shows a strong linearity, on the other hand, the nonlinear relationship between a and ${\Delta}J$ is detected in EPFM analysis. Therefore, this trend will be depended especially in the case of large scale yielding. The numerical results by the proposed model are compared with the theoretical solutions in literatures, experimental results, and the numerical solutions by the conventional h-version of the finite element method.

• Journal of Construction Engineering and Project Management
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• 제3권4호
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• pp.12-19
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• 2013

Green Frame is an environmentally friendly column-beam system composed of composite PC members that can increase buildings' life spans while reducing resource consumption. Typically, connections of PC and RC columns occur at the boundaries of each floor, which is at the upper section of slabs, causing the boundary of each floor to generate the maximum moment. Although it is not optimal in terms of structural safety to connect members at a location where the moment is high, this approach is highly adopted due to its constructability. We propose that a superior approach that employs the concept of connecting columns at the low bending moment zone can be applied to quickly and safely install green columns, the main structural members of Green Frame. Connection of green columns at the low bending moment zone can be classified into three techniques, depending on the method of reinforcing the joints, which have different connection characteristics and construction methods. Research is needed to compare the features of each method of reinforcing the joints so that the most appropriate column connection method can be chosen for the site conditions. This study aims to confirm the structural safety of the connection component at the low bending moment zone and to compare and analyze the construction duration, unit price, quality and safety performance of each column connection method. The study results are anticipated to activate the use of composite precast concrete and to be used as development data in the future.

• Journal of Ecology and Environment
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• 제39권1호
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• pp.17-29
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• 2016

We conducted the study on the relationship between the distribution of coastal sand dune plants and edaphic factors from the shoreline to inland in sand dune ecosystem. The application of TWINSPAN classification based on 10 species, led to the recognition of three vegetative groups (A-C), which associated with their habitats (foredune, hummuck in semistable zone and stable zone). The associations were separated along soil gradient far from the seashore. The relationships between species composition and environmental gradients were explained by canonical correspondence analysis (CCA). Distance from the shoreline was an important indicator to determine soil properties (pH, total ion contents, sand particle sizes, organic matters and nitrogen contents) from the seaward area to inland area and distribution pattern of coastal sand dune plants. Group A is foredune zone, characterized by Calystegia soldanella; group included typical foredune species such as Elymus mollis, Carex kobomugi, Ixeris repens, C. soldanella and Glehnia littoralis. Group B on semi-stabilized zone was characterized by Vitex rotundifolia, a perennial woody shrub. This group was associated the proportion of fine sand size (100 to 250 μm). The results on the proportion of soil particle size showed a transition in sand composition, particularly with respect to the proportion of fine sand size that occurred from the foredune ridge at 32.5 m to the Vitex rotundifolia community at 57.5 m from the shoreline. Group C on stabilized zone was characterized by Zoysia macrostachya, Lathyrus japonicus and Cynodon dactylon and were associated soil organic matter and nitrogen contents. The spatial distribution of plants in the Goraebul coastal sand dune system may result from the interactions between the plant species and environmental heterogeneity.

• 한국농공학회논문집
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• 제57권6호
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• pp.1-7
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• 2015

Most of chloride diffusion models based on finite difference method (FDM) could not express the diffusion in horizontal direction at each elevation. To overcome these weakness, two dimensional chloride ion penetration model based on finite element method (FEM) to be able to combine various multi-physics simultaneously was suggested by introducing moving mesh technique. To avoid the generation of mesh being able to be distorted depending on the relative movement of water level to static concrete, a rectangular type of mesh was intentionally adopted and the total number of meshes was empirically selected. The simulated results showed that the contents of surface chloride decreased following to the increase of elevation in the top part of low sea level, whereas there were no changes in the bottom part of low level. In the DuraCrete model, the diffusion coefficient of splashed zone is generally smaller than submerged zone, whereas the trend of Life365 model is reverse. Therefore, it could be understood that the developed model using moving mesh technique effectively reflects $DuraCrete^{TM}$ model rather than $Life365^{TM}$ model. In the future, the model will be easily expanded to be combined with various multi-physics models considering water evaporation, heat of hydration, irradiation effect of sun and so on because it is based on FEM.