• Horticultural Science & Technology
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• v.31 no.1
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• pp.1-7
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• 2013

In this study, the resistance to ozone and characteristics of ozone-induced damage were investigated on the perennial ground cover plant species. Sedum kamtschaticum and Hosta longipes were exposed to $200{\mu}g{\cdot}kg^{-1}$ ozone for 8 hours per day (from 08:00 to 16:00) in the naturally irradiated phytotron. The extent of ozone-induced damage was measured through the analysis of physiological parameters, such as water use efficiency (WUE), chlorophyll content (Chl. a, Chl. b, Chl. a + b, and Chl. a/b ratio), carotenoid contents, and the induction of reactive oxygen species (ROS). Ozone exposure significantly reduced the daytime WUE in both species. The contents of chlorophyll and carotenoid were also decreased and ROS, such as hydrogen peroxide ($H_2O_2$) and superoxide radical ($O_2{^-}$) were accumulated after ozone exposure. The above results of this study suggested that S. kamtschaticum is more resistant to atmospheric ozone than Hosta longipes. Considering its fast responses to ozone, it was also assumed that Hosta longipes can be used as an indicator plant of an increase in atmospheric ozone concentration.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.247-250
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• 1998

This study was carried out to investigate the effects of changes of ionic strength according to growth stage on growth and flowering of Dendranthema grandiflorum (Ramat.) Kitamura 'Seiun' grown hydroponically in perlite. The stage I, II, and III covered early vegetative growth (27-40 days after planting), latter vegetative growth (41-54 days), and reproductive growth (55-80 days), respectively. The 2 strength (1S and 2S) of nutrient solution were treated in stage I, whereas 3 strengths (1S, 1-2S, and 2S) were treated in stage II. Then, total 9 treatments in stage III were designated by 3 treatments (tap water, 1S, and 2S) for each 3 strengths in stage II. Each nutrient solution was applied 8 times per day. At vegetative growth stage (54 days after planting), stem length was highest when irrigated 8 times a day with 1S nutrient solution. Both photosynthesis and transpiration rate were higher in 1S than those in other treatments (1-2S, 2S), whereas leaf chlorophyll content was highest in 2S treatment. Ion content of plant treated with 2S was higher than other treatments. Growth (plant height, leaf area, stem length), fresh weight, and dry weight of each plant organ after flower bud formation were better in tap water treatment (1-1-0) than other 1S treatments (1-1-1, 1-1-2). Regarding the number of days to flowering, tap water treatment was the most effective. Thus, after flower bud formation supplying tap water or lower concentration of nutrient solution than those used during the vegetative growth stage was economical in saving chemical fertilizers, shortening the number of days to flowering, reducing salt accumulation in media, saving efforts of leaching, and reducing ground water contamination.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.93-101
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• 2010

When doing underground excavation works for the purpose of constructing large underground structures for a building in the limited space in downtown area, the stability of the adjacent ground must be top priority, and to accomplish this, it is essential to review the retaining wall construction carefully. H-Pile, which has been mainly used as a stress-carrying material in temporary earth-retaining structures, is most likely to be abandoned after completion of the works for the basement exterior wall in relation to contiguous bored piles, so it will result in a waste of material. To improve this situation, Basement Composite Wall where H-Pile and basement wall are compounded, has been developed. This wall is being used most frequently in many local construction sites. In this study, five specimens are made in order to evaluate the shear resistance of the basement composite wall and tested. Test parameter is the composition ratio and wall thickness according to shear connectors. Test result shows that the shear strength is improved when the composite ratio is increased but the magnitude is not much. A formula, which considers the contribution of concrete, web of H-pile as well as flange' effect in calculation of shear strength of composite basement wall, is suggested and used to calculation of the strength of specimens. It is found that there is a good co-relation between test result and the calculated one by the formula.

• Journal of the Korean GEO-environmental Society
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• v.16 no.7
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• pp.23-33
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• 2015

This paper is results of numerical study for application of sheet pile retaining wall reinforced with H-pile as sheet piles are needed in field for a cutoff wall and are limited to use because of driveability in the ground condition of having a larger strength than a weathered rock. Extensive 101 cases of numerical approach were conducted to investigate the behavior of sheet pile retaining wall reinforced with H-pile, changing installing members of two types of sheet pile and three types of H-pile, the embedded depth of sheet pile and H-pile, the horizontal space between H-piles and excavation conditions. As the results of numerical analysis, combined use of the sheet pile SP-IIIA with H-Pile H250 and the sheet pile SP-IV with H-Pile H350 among precast products was found to be efficient since two members tended to reach allowable stresses simultaneously or have similar stress concentration ratios. Increased stiffness in reinforced sheet pile showed reduction of lateral displacement of wall. Embedded depth of sheet pile did not affect stability of wall significantly so that driving the penetrable depth of sheet pile should be enough to maintain stability of wall and satisfy purposes of cutoff and stiffness increase of wall.

• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.747-754
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• 2021

Purpose: Seismic safety evaluation of a curved bridge must be performed since the curved bridges exhibit the complex behavior rather than the straight bridges, due to geometrical characteristics. In order to conduct the probabilistic seismic assessment of the curved bridge, Seismic fragility evaluation was performed using the uncertainty of the steel material properties of a curved bridge girde, in this study. Method: The finite element (FE) model using ABAQUS platform of the curved bridge girder was constructed, and the statistical parameters of steel materials presented in previous studies were used. 100 steel material models were sampled using the Latin Hypercube Sampling method. As an input ground motion in this study, seismic fragility evaluation was performed by the normalized scale of the Gyeongju earthquake to 0.2g, 0.5g, 0.8g, 1.2g, and 1.5g. Result: As a result of the seismic fragility evaluation of the curved girder, it was found that there was no failure up to 0.03g corresponding to the limit state of allowable stress design, but the failure was started from 0.11g associated with using limit state design. Conclusion: In this study, seismic fragility evaluation was performed considering steel materials uncertainties. Further it must be considered the seismic fragility of the curved bridge using both the uncertainties of input motions and material properties.

• Journal of the Korean Geotechnical Society
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• v.37 no.9
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• pp.5-12
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• 2021

Pseudo-static slope stability analysis method is widely used in engineering practice to calculate the seismic factor of safety of slope subjected to earthquake ground motions. Although the dynamic analysis method is well recognized to have the primary advantage of simulating the stress-strain response of soils, it is not often used in practice because of the difficult in estimating the factor of safety. In this study, a procedure which utilizes the dynamic analysis method to extract the transient dynamic factor of safety is devleoped. This method overcomes the major limitation of the pseudo-static method, which uses an empirically determined seismic coefficient to derive the factor of safety. The proposed method is applied to a slope model and the result is compared with that of the pseudo-static method. It is shown that minimum dynamic factor of safety calculated by the dynamic analysis is slightly larger than that determined from the pseudo-static method. It is also demonstrated that the dynamic factor of safety becomes minimum when the horizontal seismic coefficient and horizontal average acceleration are maximum.

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.197-206
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• 2018

BACKGROUND: The present study aimed to examine the crops capable of growing and adapting to the external environment and various stresses of reclaimed agriculture land for the development of high value-added agricultural utilization technology based on reclaimed land through standardization and empirical study of cultivation environment for cultivating crops. METHODS AND RESULTS: Two crops namely turnips and beets were selected for the salt tolerance test of soil environmental conditions on reclaimed land. Turnip and beet seedlings were planted on the soil collected at the 'Seokmun' reclaimed land. There are five treatments such as non-treatment, 1.0, 2.0 (control), 4.0 and $8.0dS{\cdot}m^{-1}$ of EC. The contents of betacyanin in beet roots was highest in control and decreased with increasing salt concentration. The GSL contents in the turnip roots waswere highest at EC 2.0 and decreased with increasing salt concentration, whereas those in turnip leaves waswere high both in the non-treated control and atthe EC 1.0-treatment. But, tThere was, however, no statistical differences among the treatments. CONCLUSION: The degree of salt tolerance of crops was examined, and the limit EC iswas expected to be $3.0{\sim}4.0dS{\cdot}m^{-1}$ as reported to date. If the soil improvement is performed and irrigation systems are used in the actual reclaimed land, the EC of supplied irrigation will be low, and desalination effecttreatment by the lower EC of the supplied irrigation on the soil will lead to more favorable soil condition of the rhizosphere and cultivation environment offor the crops than those in the port experiment. Therefore, monitoring the salinity, water content and ground water level will enable prediction of the rhizosphere environment, and setting up irrigation management and supplying irrigation will lead to crop cultivation results that are close to normal.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.55-61
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• 2011

Song-Do international city is the area developed in large-scale land reclamation. Song-Do area consists of reclamation layer, sedimentary layer(loose silt, soft clay and sand alternating) and residual layer from the ground surface. Therefore, using pile foundation is inevitable to build structures safely. In this area, driven PHC piles have been generally constructed in terms of environmental and economic conditions. As a result of analyzing 4 sites in Song-Do district 5 and 7 recently, the method of driving pile has many problems because of existence of rigid soil in sedimentary layer and installation of more than 30m piles. In this case, when installing piles by drive after pre-boring up to appropriate depth, the results of constructability analysis were very good. And in the economic efficiency, although 4% of construction cost rose, it was a very slight increase in comparison with improvement of workability. In the case of the stability, more than 70% compared to the allowable stress of piles was satisfied through the load test. As a result, when PHC piles is installed in Song-Do district, the proper construction method is that piles are located at bearing layer after boring rigid sand layer.

• Journal of Plant Biotechnology
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• v.48 no.1
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• pp.34-43
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• 2021

Targeted genome editing using the CRISPR/Cas9 system is a ground-breaking technology that is being widely used to produce plants with useful traits. However, for woody plants, only a few successful attempts have been reported. These successes have used Agrobacterium-mediated transformation, which has been reported to be very efficient at producing genetically modified trees. Nonetheless, there are unresolved problems with plasmid sequences that remain in the plant genome. In this study, we demonstrated a DNA-free genome editing technique in which purified CRISPR/Cas9 ribonucleoproteins (RNPs) are delivered directly to the protoplasts of a hybrid poplar (Populus alba × Populus glandulosa). We designed three single-guide RNAs (sgRNAs) to target the stress-associated protein 1 gene (PagSAP1) in the hybrid poplar. Deep sequencing results showed that pre-assembled RNPs had a more efficient target mutagenesis insertion and deletion (indel) frequency than did non-assembled RNPs. Moreover, the RNP of sgRNA3 had a significantly higher editing efficacy than those of sgRNA1 and sgRNA2. Our results suggest that the CRISPR/Cas9 ribonucleoprotein-mediated transfection approach is useful for the production of transgene-free genome-edited tree plants.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.59-70
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• 2022

There is a growing interest in evaluating earthquake damage and determining disaster prevention measures due to the magnitude 5.8 earthquake in Pohang, Korea. Since the liquefaction phenomena occurred extensively in the residential area as a result of the earthquake, there was a demand for research on liquefaction phenomenon evaluation and liquefaction disaster prediction. Liquefaction is defined as a phenomenon where the strength of the ground is completely lost due to a sudden increase in excess pore water pressure caused due to large dynamic stress, such as an earthquake, acting on loose sand particles in a short period of time. The liquefaction potential index, which can identify the occurrence of liquefaction and predict the risk of liquefaction in a targeted area, can be used to create a liquefaction hazard map. However, since liquefaction assessment using existing field testing is predicated on a single borehole liquefaction assessment, there has been a representative issue for the whole targeted area. Spatial interpolation and geographic information systems can help to solve this issue to some extent. Therefore, in order to solve the representative problem of geotechnical information, this research uses the kriging method, one of the geostatistical spatial interpolation techniques, and constructs a geotechnical information database for liquefaction and spatial interpolation. Additionally, the liquefaction hazard map was created for each return period using the constructed geotechnical information database. Cross validation was used to confirm the accuracy of this liquefaction hazard map.