• Horticultural Science & Technology
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• v.29 no.6
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• pp.561-567
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• 2011

Cold tolerance of the native Rhododendron species which are on the verge of extinction in Korean nature were compared with the introduced species and its mechanism were studied physiologically with the investigation of the leaf angle, leaf curling, and photosynthetic activity. The degree of cold tolerance measured with the leaf burning after winter season was higher in the native species, Rhododendron brachycarpum and Rhododendron brachycarpum var. roseum than all the introduced species. 'Nova Zembla', an introduced species, showed high sensitivity to the low temperature. Changes in leaf angle by the low temperature were bigger in 2 native species and 'Parker's Pink' than the other introduced species and small comparatively in 'Nova Zembla' and 'Cunningham's White' cultivar. Leaf curling also occurred strongly in 2 native species by the low temperature. While, it was comparatively little and mild in the other introduced species. Therefore these results suggested that the leaf movement such as leaf angle change and curling adapted to the low temperature is positively related to the cold tolerance of 2 native species. By the way, such relationship is not explainable in the cold-sensitive 'Parker's Pink' cultivar showing comparatively stronger leaf movement. Photosynthetic activity measured before the winter season was high in the cold-tolerant R. brachycarpum and its recovery after winter season was faster in the 2 native species and the introduced 'Cynosure' cultivar than the other introduced species. They were the lowest in the most cold-sensitive 'Nova Zembla'. This phenomena occurred similarly even in the stomatal conductivity, suggesting that the movement of water from the roots to the leaves is better and then the leaf burning after winter season become small in the cold-tolerant species. The recovery of photosynthetic activity and stomatal conductivity was comparatively slower in the cold-sensitive 'Parker's Pink'. From the above results, leaf behavior adapted to the low temperature during the winter season and water movement to the leaves are related collectively to the cold tolerance represented as the leaf burning in the Rhododendron species is suggested.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.46-54
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• 2016

2-Oxoglutarate (2OG) acts as a signaling molecule and plays a critical role in secondary metabolism in a variety of organisms, including plants. Six 2-oxoglutarate (2OG) and Fe(II) oxygenase (2OGO) genes, VlCE2OGO1 [Vitis labruscana 2-oxoglutarate (2OG) and Fe(II) oxygenase 1], VlCE2OGO2, VlCE2OGO3, VlCE2OGO4, VlCE2OGO5, and VlCE2OGO6, which show different expression patterns upon transcriptome analysis of 'Campbell Early' grapevine exposed to low temperature for 4 weeks, were analyzed for their structure and expression. Comparison of the deduced amino acid sequences of the 2OGO genes from the V. labruscana transcripts revealed sequence similarities of 38.6% (VlCE2OGO1 and VlCE2OGO2) to 19.2% (VlCE2OGO2 and VlCE2OGO3). The lengths of these genes ranged from 1053 to 2298 bp, and they encoded 316 to 380 amino acids. The prediction of the secondary structure of the encoded proteins by Self-Optimized Prediction Method with Alignment (SOPMA) indicated that all the genes contained alpha helix (23.95 to 41.71%), extended strand (16 to 22.34%), beta turn (6.65 to 9.22%), and random coil (32.97 to 51.58%) in the analysis. Specific primers from unique regions in each gene obtained by alignment of nucleotide sequences were used in real time PCR for analysis of gene expression. All tested genes showed differential expression in grapevines exposed to low temperature. Of the six transcripts, VlCE2OGO1, VlCE2OGO2, and VlCE2OGO3 were up-regulated and VlCE2OGO4, VlCE2OGO5, and VlCE2OGO6 were down-regulated in response to cold treatments at all tested time points. The 2OG genes can be used for elucidation of mechanisms of tolerance to cold and as valuable molecular genetic resources for selection in breeding programs for cold-hardy grapevines.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.203-211
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• 1995

This study was conducted to know how low temperature response of rice varieties is available for breeding lines adapted to cold weather. Some agronomic characters related to cold tolerance were evaluated for 188 varieties including three varietal types of Japonica, Tongil, and Indica. Cold tolerance of Japonica and Indica type varieties varied in leaf discoloration, heading delay, reduction of culm length, panicle number, spikelet number, panicle exsertion, spikelet fertility, and phenotypic acceptability at maturity, while Tongil type varieties were susceptible in most agronomic characters. In leaf discoloration, most Japonica type varieties were highly tolerant, while Indica type varieties showed various responses from tolerant to susceptibility. Not significant difference among three varietal types was observed on reduction of panicle number and spikelet number due to low temperature.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.1
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• pp.13-18
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• 2000

Low temperature co-fired ceramics on metal (LTCC-M) is efficient for embedding passive components with good tolerance in a module due to the dimensional stability in x and y directions by the constraint of metal core during the firing. In addition, the radiation noise can be reduced by metal core. In this paper, embedded passive components were introduced and a power amplifier module (PAM) fabricated by using the passive components was explained. The embedded passive components in test patters showed the tolerance of 10~20% and the good repeatability in tolerance of embedded passives was maintained in module fabrication. The shortened traces in multi chip modules (MCMs) make the signal delay time decreased and the embedded passives simplify the packaging processes owing to the less solder points, which enhance the electrical performance and increase the reliability of the modules. The LTCC-M technology is one of the promising candidates for RF application and is expected to expand its applications to power and high performance devices.

• Molecules and Cells
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• v.27 no.4
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• pp.449-458
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• 2009

The OsAsr1 cDNA clone was isolated from a cDNA library prepared from developing seed coats of rice (Oryza sativa L.). Low-temperature stress increased mRNA levels of OsAsr1 in both vegetative and reproductive organs. In situ analysis showed that OsAsr1 transcript was preferentially accumulated in the leaf mesophyll tissues and parenchyma cells of the palea and lemma. For transgenic rice plants that over-expressed full-length OsAsr1 cDNA in the sense orientation, the Fv/Fm values for photosynthetic efficiency were about 2-fold higher than those of wild type-segregating plants after a 24-h cold treatment. Seedlings exposed to prolonged low temperatures were more tolerant of cold stress, as demonstrated during wilting and regrowth tests. Interestingly, OsAsr1 was highly expressed in transgenic rice plants expressing the C-repeat/dehyhdration responsive element binding factor 1 (CBF1), suggesting the regulation of OsAsr1 by CBF1. Taken together, we suggest that OsAsr1 gene play an important role during temperature stress, and that this gene can be used for generating plants with enhanced cold tolerance.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.93-101
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• 2014

This study aims to investigate the effect of heat input of outside SAW weld on low temperature toughness($-20^{\circ}C$) of inside SAW weld for API 5L X70 with sour gas resistance. As increasing heat input of the outside weld, low temperature toughness of the inside weld was decreased. Especially, in spite of the same heat input, the value of low temperature toughness was fluctuated. On the basis of fracture and microstructure analysis, the low temperature toughness is correlated with the fracture area ratio of shear lips and four kinds of fracture sections. These sections were divided with size and shape of dimple correlated with grain boundary ferrite and cleavage correlated acicular and polygonal ferrite in grain. Therefore, it was seen that these sections were two of final solidification area in the inside weld and the outside weld, no reheated zone and reheated zone in the inside weld. In conclusion, it is thought that the difference of low temperature toughness at the same heat input is due to the fact that each of impact test specimens could have the different microstructure, even though the notch was machined under the error tolerance of 1mm. It is because the final solidification area of the inside weld is very narrow.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.10
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• pp.928-935
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• 2015

This paper presents low temperature structural tests of a UAV wing which has room temperature-curing adhesive bond. The wing structure is made of carbon fiber reinforced composites, and the skins are bonded to the inner structures (such as ribs and spars) using room temperature-curing adhesive bond. Also, to verify damage tolerance design of the wing structure, barely visible impact damages are intentionally created in the critical areas. The attachment fittings of the wing are fixed in a specially designed chamber which can simulate the low temperature environments of the operating altitudes. The test load is applied by hydraulic actuators which are placed outside the chamber. The structural tests consist of strain survey tests and a durability test for 1-life fatigue load spectrum. During the tests, strains of major parts are measured by strain gauges and FBG sensors. The change of the initial impact damages is also monitored using piezoelectric sensors. The 1-life damage tolerance of the composite structure is verified by the structural tests under the simulated environments.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.43-49
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• 2016

PURPOSES : The field application and performance of continuously reinforced concrete pavement (CRCP), constructed by using the mechanical tube-feeding method, are evaluated in this study. METHODS: The location of the rebar was evaluated by using the MIRA system. The early-age CRCP performance was evaluated via visual survey, in which the crack spacing and crack width were examined. RESULTS: The location of longitudinal reinforcing bars was evaluated via MIRA testing and the results showed that the longitudinal rebars all lie within a given tolerance limit (${\pm}2.5cm$) of the target elevation. In addition, owing to the low temperature when the concrete was pured, the crack spacing in the Dae-Gu direction is slightly wider than that of the Gwang-Ju direction. Almost all of the crack spacings lay within the range of 1.0 m~3.0 m. A crack width of <0.3 mm was measured at the pavement surface. However, as revealed by the field survey, the crack spacing was not correlated with the crack width. CONCLUSIONS : In CRCP constructed by using the mechanical tube-feeding method, almost all of the longitudinal reinforcing bars lay within the tolerance limit (2.5 cm) of the target elevation. The concrete-placing temperature affects the crack spacing, owing to variations in the zero-stress temperature. Crack survey results show that there is no correlation between the crack spacing and crack width in CRCP.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.258-266
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• 1998

The purpose of this study is to investigate the actual conditions, to find problems, and to present an improvement plan of interior landscape in the subway stationis. Moreoiver, it will presume the possibilties to develop the subway and ways to utilie underground space effectively. The results are summarized as follows A light intensity was recorded 0-100 Lux as the lowest light and 500 Lux below as the highest in 61 subway stations. An average temperature of 12 $^{\circ}C$and an air humidity of 38% were recorded over a 4 month period from January to April, but includes a drastic variaton between -8.5$^{\circ}C$ and 21.5$^{\circ}C$. Soil acidity of pH 7 below and soil moisture of 1-2 wet degree were apeared in subway stations mostly. Plant forms consisted of artificial flower & flower. Plant species were recorded at a total of 54 species and appeared in the order of Araucaria heteropylla, Ophiophogon jaburan, Aspidistra elatior cv. 'Asahi' and Hedera helix. Plant height was, for the most part, below 0.5m. Plant species that was fined of conditions were Palm, Camellia japonica, Araucaria heterophylla as a high plant, dracaena fragrans, dracaena deremensis cv. Wakneckii as a middle plant, and Ophiopogon jaburan, Hedra helix, ytomium falcatum, Aspidistra elatior cv. Asahi as a low plant. It used to water materials such as small pool, small cascade, water cycles and natural materials such as natural rock, small rock, sand, bark and animal materials such as squirrels, birds, goldfish as an object for plants in the subway stations. From these actual conditions, First of all, It must make up physical environments such as light, temperature humidity, soil for plant growth, and is important to chooce suitable indoor plants and draw up systematic management in the subway environments. Also, it change plants frequently and uses variable objects for subway stationi individuatism, Moreover, indoor plants with strong environmental adaptation abities such as shade tolerance, drought tolerance and cold tolerance need to develope variable species possibly. If these improvements occur, utilization and amenity of subway stationis will increase, according to the use of interior landscape.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.4
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• pp.439-445
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• 2007

Proton exchange membrane Fuel Cells(PEMFCs) have been spotlighted because of their broad potential application for potable electrical devices, automobiles and residential usages. However, their utilization is limited to low temperature operation due to the electrolyte dehydration at high temperature. High temperature PEMFC operation offers high CO tolerance and easy water management. This review presents development of high temperature($120{\sim}200^{\circ}C$) PEMFC. Especially, PEMFC which is based on acid-doped PBI membrane is discussed.