• Korean Journal of Plant Taxonomy
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• v.35 no.4
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• pp.227-245
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• 2005

Numerical analysis using morphological characters was done in order to clarify taxonomic circumscriptions and identities of Korean endemic, Cirsium setidens (Dunn) Nakai, Cirsium chanroenicum Nakai, and Cirsium toraiense Nakai ex Kitam.. Principal components analysis of C. setidens and C. chanroenicum using 29 morphological characters and 12 leaves characters revealed one group which could not separate. Identity of C. toraiense could not be confirmed by the destruction of habitat, similarity of morphological diagnostic characters between many specimens identified C. toraiense including type specimen and C. japonicum var. ussuriense. In considering the variational patterns of morphological characters, it is strongly suggested that identities of C. setidens f. alba, C. setidens var. niveo-araneum, and C setidens var. pinnatifolium should be recognized, but C. chanroenicum var. lanceolata should be included to circumscription of C. setidens.

• International Journal of High-Rise Buildings
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• v.1 no.4
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• pp.311-332
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• 2012

Earthquake response of mid-rise to high-rise buildings provided with friction dampers is investigated. The steel buildings are modelled as shear-type structures and the investigation involved modelling of the structures of varying heights ranging from five storeys to twenty storeys, in steps of five storeys, subjected to real earthquake ground motions. Three basic types of structures considered in the study are: moment resisting frame (MRF), braced frame (BF), and friction damper frame (FDF). Mathematical modelling of the friction dampers involved simulation of the two distinct phases namely, the stick phase and the slip phase. Dynamic time history analyses are carried out to study the variation of the top floor acceleration, top floor displacement, storey shear, and base-shear. Further, energy plots are obtained to investigate the energy dissipation by the friction dampers. It is seen that substantial earthquake response reduction is achieved with the provision of the friction dampers in the mid-rise and high-rise buildings. The provision of the friction dampers always reduces the base-shear. It is also seen from the fast Fourier transform (FFT) of the top floor acceleration that there is substantial reduction in the peak response; however, the higher frequency content in the response has increased. For the structures considered, the top floor displacements are lesser in the FDF than in the MRF; however, the top floor displacements are marginally larger in the FDF than in the BF.

• Korean Journal of Plant Taxonomy
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• v.45 no.2
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• pp.178-182
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• 2015

Stellaria sessiliflora Y. Yabe (Caryophyllaceae), which is known to be distributed throughout Japan excluding Okinawa, was recently found on Jeju Island in Korea. Reports on the Japanese flora state that this species is distributed on Jeju Island, and a photograph of one specimen (Slide No. 6294) collected from Jeju Island by Ohwi in May 1935 confirms this. Additionally, specimens at the National Arboretum and Korea Forest Research Institute indicate that S. sessiliflora has occurred on Jeju Island for a considerable amount of time. However, the species has never been officially listed in the flora of Korea. Stellaria sessiliflora is distinguished from S. media by having broader leaves with a slightly undulate margin, petiolate leaves on the upper part of the stem, and 10 stamens. The local name 'Geu-Neul-Byeol-Kkot' is given to the species based on its shady habitat under deciduous broadleaf forest. Details of the morphological characters, an illustration, the type specimen, voucher specimen data, and photographs of Stellaria sessiliflora in Korea are presented.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.317-323
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• 2012

Fragmented urban forests, as green islands within urban area, are the primary habitats for a vast number of different organisms inhabiting large cities. The areas of the urban forests are usually small, and hence, the proportion of the forest edge is relatively high. It is therefore expected that overall butterfly diversity may be lower than that of suburban or rural forests, and that those of grassland species, forest edge species, and generalist species with a wider niche breadth may be richer. Butterflies were surveyed weekly by the line transact method in order to characterize the butterfly community of the Hongneung Forest, a fragmented urban forest in Seoul. Butterfly richness of the study forest is much lower than those of main forests around or in Seoul. Grassland species, forest edge species, and generalist species were found to be richer, which was in agreement with the expected patterns of urban butterfly communities. Also, an endangered species, Spindasis takanonis, was observed in the Hongneung Forest, showing that urban forests play important roles for conservation of rare species.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1001-1009
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• 2002

Vegetative characters (e.g. habitat, root, ramification and habit of stem, phyllotaxy, leaf sape, shape of leaf margin, shape of division and lobe of division, number of division, thick and texture of leaf and shape of stipule) on 35 species of Asian Geranium were reviewed to discussion propriety of taxonomic character and evolutionary trends. Wilfordii group is characterized by three divided leaf, Farreri group was grown a high altitude, and Maculatum group is grouped by life cycle of anneal. Arrangement state of leaf is alternate type G, tripartitum, G. eriostemon, and G. erianthum is thought the more primitive than the other taxon, and regarded as more advanced group the sibiricum group and pseudosibiricum group which divided of leaf deeply. Shape of leaf, division degree of lobes, shape of leaf margin and number of division are considered a good identification characters because width of change are fixed between population.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.188-194
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• 2015

River channel dredging and riparian development have been influenced morphology and quantity of natural river habitat. We compared distribution of riverside land and alluvial island in the Nakdong River with field survey and remote sensing analysis after the 4 Large River Project in South Korea. We digitized geomorphological elements, includes main channel, riverside land, and alluvial island by using georeferenced aerial photos taken in pre-dredging (2008) and post-dredging (2012) periods. Field survey was followed in 2012 for a ground truth of digitized boundaries and identification of newly constructed wetland types such as pond, channel, branch, and riverine type. We found that during the dredging period, riverside land and alluvial island were lost by 20.2% and 72.7%, respectively. Modification rate of riverside land was higher in the section of river kilometer 50~90, 140~180, and 210~270. Alluvial island had higher change rate in the section of river kilometer 50~70, 190~210, and 270~310. Average change rate for the riverside land and alluvial island was $-1.02{\pm}0.14km^2{\cdot}10km^{-1}$ and $-0.05{\pm}0.05km^2{\cdot}10km^{-1}$, respectively. Channel shaped wetlands (72.5%) constituted large portion of newly constructed wetlands.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.855-863
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• 2019

The efficiency of fishway installed in rivers can be directly evaluated by means of fish monitoring. On the other hand, when it is difficult to monitor the fish in certain conditions, or when planning a fishway, the efficiency can be evaluated indirectly through the hydraulic analysis. In this study, the hydraulic analysis technique for evaluating the efficiency of a fishway was presented. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area was proposed as an index of the efficiency. In the analysis of passage efficiency, the three-dimensional model, Flow-3D, was used as an evaluation tool to describe the fluid behavior on a hydraulic structure with free surface. The ice-harbor type fishway at Baekgok weir in the Deokcheon River was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. And then it was compared with fish monitoring data acquired from the river. As a result, it is difficult to replace the hydraulic analysis results with the efficiency quantitatively, but it can help to grasp the general tendency.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.323-334
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• 2021

Concrete structures may rarely collapse in fire incidents but fire induced damage to structural members is inevitable as a result of material degradation and thermal expansion. This requires certain repairing measures to be applied to restore the performance of post-fire members. A brief review on investigation of post-fire damage of concrete material and concrete structural members is presented in this paper, followed by a review of post-fire repair research regarding various types of repairing techniques (FRP, steel plate, and concrete section enlargement) and different type of structural members including columns, beams, and slabs. Particularly, the fire scenarios adopted in these studies leading to damage are categorized as three levels according to the duration of gas-phase temperature above 600℃ (t₆₀₀). The repair effectiveness in terms of recovered performance of concrete structural members compared to the initial undamaged performance has been summarized and compared regarding the repairing techniques and fire intensity levels. The complied results have shown that recovering the ultimate strength is achievable but the stiffness recovery is difficult. Moreover, the current fire loading scenarios adopted in the post-fire repair research are mostly idealized as constant heating rates or standard fire curves, which may have produced unrealistic fire damage patterns and the associated repairing techniques may be not practical. For future studies, the realistic fire impact and the system-level structural damage investigation are necessary.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.265-283
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• 2021

To ensure that fire induced collapse of a building is prevented it is important to understand the sequence of events that can lead to this event. In this paper, the initiation of collapse mechanisms of generic a multi-storey steel frame subjected to vertical and horizontal travelling fires are analysed computationally by tracking the formation of plastic hinges in the frame and generation of fire induced loads. Both uniform and travelling fires are considered. In total 58 different cases are analysed using finite element software LS-DYNA. For the frame examined with a simple and generic structural arrangement and higher applied fire protection to the columns, the results indicate that collapse mechanisms for singe floor and multiple floor fires can be each split into two main groups. For single floor fires (taking place in the upper floors of the frame (Group S1)), collapse is initiated by the pull-in of external columns when heated beams in end bays go into catenary action. For single floor fires occurring on the lower floors(Group S2), failure is initiated (i.e. ultimate strain of the material is exceeded) after the local beam collapse. Failure in both groups for single floor fires is governed by the generation of high loads due to restrained thermal expansion and the loss of material strength. For multiple floor fires with a low number of fire floors (1 to 3) - Group M1, failure is dominated by the loss of material strength and collapse is mainly initiated by the pull-in of external columns. For the cases with a larger number of fire floors (5 to 10) - Group M2, failure is dominated by thermal expansion and collapse is mainly initiated by swaying of the frame to the side of fire origin. The results show that for the investigated frame initiation of collapse mechanisms are affected by the fire type, the number of fire floors, and the location of the fire floor. The findings of this study could be of use to designers of buildings when developing fire protection strategies for steel framed buildings where the potential for a multifloor fire exists.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.2
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• pp.85-102
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• 2021

Phytosociological characteristics on Quercus acutissima forests distribution in Daechong-dam basin survey has been carried out using Z.-M. School's methodology and numerical-classification analyses. A total of 43 phytosociological relevés were sampled. Syntaxa were described as Oplismenus undulatifolius-Quercus acutissima community(typicum subcommunity, Phryma leptostachya var. asiatica subcommunity, Ulmus davidiana var. japonica subcommunity), Quercus acutissima community and Quercus variabilis-Quercus acutissima community (typicum subcommunity, Castanea crenata subcommunity). The above three plant communities were classified with species composition reflecting local environmental characteristics of mountain topographies, inclination degrees, and rock exposure rates. Conclusively, those communities were recognized as secondary vegetation affected by high intensity and frequency of human impacts as they inhabited in southward hill lands and low lying grounds in mountains adjacent to human settlements and arable lands. Quercus acutissima community was classified as rural type syntax based on their inlandward distribution and species composition differences from urban forests. Afforest process and natural succession were discussed in relation with habitat environmental elements of Quercus acutissima forest in the survey area.