• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.53-66
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• 2000

This paper proposes a simple numerical model for use in a finite analysis (FEA) of scaffold-shoring systems. The structural model consists of a single set of multiple-story scaffolds with constraints in the out-of-plane direction at every connection joint between stories. Although this model has only two dimensions (termed the 2-D model), it is derived from the analysis of a complete scaffold-shoring system and represents the structural behavior of a complete three-dimensional system. Experimental testing of scaffolds up to three stories in height conducted in the laboratory, along with an outdoor test of a five-story scaffold system, were used to validate the 2-D model. Both failure modes and critical loads were compared. In the comparison of failure modes, the computational results agree very well with the test results. However, in the comparison of critical loads, computational results were consistently somewhat greater than test results. The decreasing trends of critical loads with number of stories in both the test and simulation results were similar. After investigations to explain the differences between the computationally and experimentally determined critical loads, it was recommended that the 2-D model be used as the numerical model in subsequent analysis. In addition, the computational critical loads were calibrated and revised in accordance with the experimental critical loads, and the revised critical loads were then used as load-carrying capacities for scaffold-shoring systems for any number of stories. Finally, a simple procedure is suggested for determining load-carrying capacities of scaffold-shoring systems of heights other than those considered in this study.

• Journal of the Korea Construction Safety Engineering Association
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• s.38
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• pp.79-87
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• 2006

Formwork is a temporary structure that supports its weight and that of freshly placed concrete as well as construction live loads. In constructions site, pipe supports are usually used as shores which are consisted of the stab formwork. The strength of a pipe support is decreasing as it is frequently being used at the construction site. Among the accidents and failures that occur during concrete construction, there are many formwork failures which usually happen at the time concrete is being placed. The objective of this study is to find out the strength change of used pipe support and unused pipe supports according to aging. In this study, 2857 pipe supports were prepared. Among these pipe supports, 2337 pipe supports were lent to the construction companies free of charge. 520 pipe supports were kept on the outside. Compressive strength was measured by knife edge test and plate test at each 3 month. Test results show that the strength of unused pipe supports as well as used pipe supports was decreasing according to age, use frequency and load carrier, and the strength of used pipe supports was lower than the strength of unused pipe supports at the same age. So, the strength of used pipe supports from 191 days to present day was not satisfied the specification of KSF 8001. In this study, the strength of pipe support according to age, use frequency and load carrier was predicted using SPSS 12.0. It was known that the strength of pipe support using for 5 years was reduced to 42.8%. According to these results, it shows that attention has to be paid to formwork design using used pipe supports. Therefore, the present study results will be able to provide a firm base to prevent formwork collapses.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1365-1374
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• 2010

The maritime traffic is more complex these days. It is more hard for the small fishing ships to navigated in shores. The requirements for the navigate information system to protect the sea environments and support the small fishing ships are more increased. However, the Inmarsat communication system is too burden to the fishermen with the expensive terminal and call fees. We propose the wireless digital fishing information network which use the existing MF/HF SSB communications system by connecting I-PHONE, PDA, NetBook, Notebook, PC, etc with the PSK31 method and AIS(Automatic Identification System) on the MF/HF radio Band.

• ALGAE
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• v.27 no.3
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• pp.189-196
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• 2012

Twelve morphological characters and the biochemical composition of Undaria pinnatifida f. distans sporophytes growing on the rocky shores of Jindo and Wando and on cultivation ropes in Kijang were measured to determine whether each population could be characterized by morphological features and biochemical composition. The goal of this study was to compare phenotypic variations between populations as they relate to environmental conditions. The sporophytes of the Kijang population were two times longer and 19 times heavier than those at Jindo. Sporophylls of the Jindo U. pinnatifida population were significantly smaller in length, width, frill number, and weight than those at Wando and Kijang. Kijang Undaria plants showed the highest contents of total protein, crude fiber, total amino acids, the amount of essential amino acids, the proportion of total unsaturated fatty acids, and eicosapentaenoic acid. However, the Jindo population showed the greatest content of carbohydrates, lipids, and minerals (Zn and Ca) of the three U. pinnatifida populations. In particular, Zn content of Jindo plants was 30 times greater than that of Kijang plants. Thus, the proximate composition, mineral composition, amino acids, and fatty acids of Undaria pinnatifida plants were distinguishable among the three representative Undaria populations evaluated. These results suggest that morphological and biochemical differences of the three U. pinnatifida populations can be attributed to differences in environmental conditions of their habitats.

• Development and Reproduction
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• v.21 no.1
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• pp.101-110
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• 2017

On June 14, 2008 (the first experiment) and July 24, 2008 (the second experiment), the shores of the Boseong River and the sandy beaches, Seokgok-myun, Moksadong-myun, Gokseong-gun in Jeollanam Province were investigated and a total of 29 soft-shelled turtle (Tryonyx sinensis) eggs in the natural spawning nest eggs were collected (13 eggs were collected in the first experiment and 16 eggs in the second experiment). The temperatures in the natural spawning nests were $25.9-36.9{\pm}0.5^{\circ}C$, the depth of the eggs was $5.2-7.5{\pm}0.5cm$ as the distance of the average $6.4{\pm}0.5cm$. 29 eggs were scattered at least 0.2 cm interval. Artificial incubation of 29 eggs was conducted in artificial nest boxes in thermo-plastic composition of the incubator, and then incubated at $26.5-35.5{\pm}0.5^{\circ}C$, and an average constant temperature was $31.2-32.1{\pm}1.0^{\circ}C$. The incubation days ranged from 53 to 55. In case of most turtles, incubation at $31^{\circ}C$ (higher temperatures) generally produces all or mostly females, while incubation at $25^{\circ}C$(cooler temperatures) produces all or mostly males. Exceptionally, in case of genus Trionyx, the sex ratio of female : male of T. sinensis of a freshwater soft-shelled turtle was approximately 1:1, which differs from other genera of turtles and makes T. sinensis Strauch only turtles presently known to lack temperature-dependent sex determination.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.225-231
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• 2013

To study the characteristics of rocky intertidal invertebrate fauna on the coastal areas of the East Sea, seven regions including Dokdo, Ulleungdo, Gyeongju, Pohang, Yeongdeok, Uljin, and Gangwondo, the common species ratio (%) and similarity index using Bray-Curtis similarity matrix were calculated. The contributed species for dissimilarity between Dokdo and the other East Sea's coastal areas were selected by using SIMPER. The common species ratio and the cluster analysis showed that Ulleungdo presented the highest similarity. However, Yeongdeok showed the highest similarity in the eastern costal areas, and Gangwondo showed the lowest one. However the cluster analysis revealed the discrimination of the rocky intertidal invertebrate community on Dokdo with others region caused by the particularity of rocky shores exposed to strong wave action and by the particular distribution of rocky intertidal invertebrate fauna in Dokdo.

• Animal Systematics, Evolution and Diversity
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• v.27 no.1
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• pp.1-17
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• 2011

Thais Roding, 1798, commonly known as rock-shell, is among the most frequently found gastropod genera worldwide on intertidal rocky shores including those of Japan, China, Taiwan and Korea. This group contains important species in many marine environmental studies but species-level taxonomy of the group is quite complicated due to the morphological variations in shell characters. This study examined the genetic variations and relationships among three Korean Thais species based on the partial nucleotide sequences of mitochondrial cox1 gene fragments. Phylogenetic trees from different analytic methods (maximum parsimony, neighbor-joining, and maximum likelihood) showed that T. bronni and T. luteostoma are closely related, indicating the most recent common ancestry. The low sequence divergence found between T. luteostoma and T. bronni, ranging from 1.53% to 3.19%, also corroborates this idea. Further molecular survey using different molecular marker is required to fully understand a detailed picture of the origin for their low level of interspecific sequence divergence. Sequence comparisons among conspecific individuals revealed extensive sequence variations within the three species with maximum values of 2.43% in T. clavigera and 1.37% in both T. bronni and T. luteostoma. In addition, there is an unexpectedly high level of mitochondrial genotypic diversity within each of the three Korean Thais species. The high genetic diversity revealed in Korean Thais species is likely to reflect genetic diversity introduced from potential source populations with diverse geographic origins, such as Taiwan, Hong Kong, and a variety of different coastal regions in South China and Japan. Additional sequence analysis with comprehensive taxon sampling from unstudied potential source populations will be also needed to address the origin and key factors for the high level of genetic diversity discovered within the three Korean Thais species studied.

• Ocean and Polar Research
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• v.37 no.4
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• pp.317-325
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• 2015

To evaluate the relative ecological quality of Taean coastal areas in terms of various seaweed community indices, seasonal samplings were taken at the Hakampo, Padori, Chaeseokpo, Mongsanpo and Bangpo shores from March 2006 to January 2007. A total of 105 species were identified; species richness ranged from 37~72 species spatially and from 65~75 species seasonally over the study period. Coarsely-branched seaweeds were dominant in functional group and ESG I (ecological state group I) made up 61 species (58.10%) of the identified macroalgae. The average seaweed biomass at the five study sites was $56.63g\;dry\;wt./m^2$ (range, 36.66 at Hakampo $-73.89g/m^2$ at Mongsanpo). Seaweeds were generally abundant in mid and low intertidal zone. Corallina pilulifera, Ulva australis, Sargassum thunbergii, Neorhodomela aculeata, and Symphyocladia latiuscula were the dominant species across all five study sites. Species diversity was between 1.24~2.30, while species evenness was between 0.40 and 0.61. The dominance index ranged from 0.43 at Padori to 0.64 at Mongsanpo. Given the community indices and shore descriptions, the five study sites were divided into two groups based on ecological quality: moderate (Chaeseokpo and Mongsanpo) and good (Hakampo, Padori and Bangpo).

• Economic and Environmental Geology
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• v.18 no.1
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• pp.55-63
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• 1985

Studies based on field observation and laboratory analysis of the littoral sands of beaches in Jeju Island indicate that the shores exhibit a great variation in both the beach geometry and the composition in terms of geological agents. Most of the beaches around the Island are developed in relatively small patches and discontinuous, as the result of intervening sea cliffs and rocky headlands. The sand quality and the dimensions of the beaches in the Island are relatively poor; for example, these beaches are 220~2,780m in length, 41~313m in width, and $7^{\circ}$ steepness in average foreshore slope. According to the textural parameters analysis, the beach sediments in study portion shows medium grained ($average\;1.42{\phi}$), moderately well sorted ($average\;0.65{\phi}$) and negative skewed ($average\;0.34{\phi}$), which seems to reflecting a high energy marine depositional environment. The heavy and light minerals of te beach sediments are composed of quartz, volcanic fragments, Na-Ca feldspar, olivine, augite as major constituents, along with apatite, biotite and other minor components, which originates from the adjacent geology. The content of CaO-MgO in shell fragments of the littoral sands ranged from 4.69~51.96%, suggesting that the high CaO-MgO content in some of the Island's beaches is attributable to geologic environments conducive to the growth of shell organisms and sediments migration. The provenance of the sediments studied are derived predominantly from adjacent continental shelves and/or terrigenous older river portion, Which sediments were transported mostly by rolling or bottom suspension. The depositional environments of the Jeju beaches can be divided into two types: beaches distributed in the North and the Northeastern parts of the Island are dominated by marine enviroment, whereas beaches in the Southwestern portion are characterized by terrigenous agencies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.220-228
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• 2010

A steel wire-integrated deck plate that welds integrated triangle truss steel wires on a galvanized steel sheet is developed to reduce construction costs of a slab or formwork such as shores and supports, and it is already widely applied in many construction fields. This study selected upper and lower steel wires, lattice steel wires, span, and cutting methods of ends as variables, and conducted an experimental test by manufacturing a total of 32 full scale test bodies. According to the result, changes in final destruction types of the test bodies and cutting methods of ends didn't affect structural performance of test bodies, and for a 3.2m-span test body, there was no big problems in using ${\Phi}4.5$ of lattice steel wires.