• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.2
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• pp.193-200
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• 2010

Due to the characteristic of culvert structure, the standard section of the culvert has been established and applied in field. However, this becomes a limitation in selecting a section design corresponding to various field conditions although it can improve the design and applicability of culvert structure. In order to overcome this limitation, we have developed the design and application technology of culvert structure corresponding to the field conditions that various shapes of culvert structure can be covered by assembly of precast segments. Because the structural characteristics of assembling-type waterway culvert structure, the thickness of structure and amount of reinforcing rods can vary according to the fixation or internal hinge status in the connection part of precast segments. This has a strong influence on the applicability and economic efficiency of culvert structure. Accordingly, in order to suggest a reasonable modeling technique of segment connection parts, this study has conducted the field experiment and numerical analysis. According to the results of field experiment and numerical analysis, the slab, wall and base slab with mortar splice sleeves have shown that the assembling-type of waterway culvert structure behaves like an integrated structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.709-719
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• 2023

In general, most of the electrical equipment responsible for control within power plants is housed in self-standing cabinets. These cabinets are typically fixed to a slab using post-installed anchors. Although the fixation method of using post-installed anchors provides stability, there is a risk of conductor failure due to external forces, including moments. However, the performance assessment of current anchors is only evaluated through uniaxial material tests. Therefore, the primary purpose of this study is to compare the static performance of post-installed anchors, considering on-site installation conditions, with their performance in material tests and to analyze the behavioral characteristics of the anchors. While conducting experiments using actual cabinets would be ideal, practical and spatial constraints make this approach difficult. As an alternative, experiments were conducted using a test specimen consisting of a steel column and a support. As a result, the pull-out performance of anchors reflecting on-site installation conditions was measured to be about 10% higher than that observed in material tests. The trends in load reduction and the point of maximum performance for the anchors also differed. To verify the reliability of the experimental study, a 3D FEM analysis was performed, which will provide predictive information on the loads transferred to the post-installed anchors for structural performance evaluations of electrical cabinets using shaking table test in the future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.121-127
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• 2024

In this study, the applicability of replacing DG(Desulfurized Gypsum) from oil refinery with CCCMs(Carbon dioxide Conversion Capture Materials) as an ALC(Auto-claved LIghtweight Concrete) raw material was examined, and basic properties of ALC was measured. The main chemical components of DG and CCCMs were CaO and SO₃, and an increase in LOI(Loss of ignition) due to mineral carbonation reaction was verified. The crystalline phases of CCCMs were CaCO₃, CaSO₄, Ca(OH)₂, and CaSO₄·2H₂O. When DG, a raw material for ALC production, was replaced with CCCMs, foaming height, pore shape, absolute dry gravity, and compressive strength results measured similar for all binders. In addition, the formation of tobermorite which is main crystalline phase of ALC was shown for all specimens in microstructural analysis.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.43-53
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• 1987

In order to improve effectiveness of rhizobia- legume symbiotic nitrogen fixation, ecological and physiological characteristics of indigenous rhizobia distributed in Korea, that is, symbiotic effectiveness of indigenous soybean rhizobia, nitrate reductase activities of the soybean bacteroid from five different soils, and differences of host-infection abilities among the soybean cultivars under population densities of the same indigenous soybean rhizobia, were investigated. The results were summarized as follows: 1. The number of indigenous soybean rhizobia was ranged from $9.2{\times}10^2$ cells per gram of soil in calcareous soil II to $42.4{\times}10^3$ cells per gram of soil in calcareous soil I in Danyang. 2. The symbiotic effectiveness of indigenous soybean rhizobia from five different soils was high in the case of soybean continuously cultivated, and calcareous soil I that population densities of indigenous soybean rhizobia were observed highly. 3. Inverse relationship was observed between total nitrogenase activity (TNA) and nitrate reductase activity (NRA) from the soybean bacteroids ($r=-0.502^*$), but the correlation between nitrate reductase and specific nitrogenase activities (SNA) could be devided into two groups. It was classified into group I which is high in SNA and low in NRA, and group II which is low in SNA and high in NRA. 4. The infection ability of the indigenous soybean rhizobia in the same soil conditions showed the reciprocal difference among each soybean cultivars. In Kwangkyo and Jangyeup, the symbiotic effectiveness appeared by infection of indigenous soybean rhizobia was higher than it of the other soybean cultivars.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.323-330
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• 2013

This study was conducted to know the effect of major physical-chemical characteristics of soil to be in the area of indigenous and naturalized plant in the sand dune of the western coastal area of Korea. The study was performed on the sand dunes distributed across Taean-gun and Buan-gun and the study period was from April to October in 2010. Sixty nine of $5m{\times}5m$ study plots were installed and the distribution of plants were investigated. We measured the soil characteristics including soil pH, organic matter, total nitrogen, available $P_2O_5$, soil cation exchange capacity, exchangeable cation, EC and NaCl. As a result, soil texture was classified as sand, in case of average pH, NaCl, and EC of soil to be in the area of indigenous herbaceous plant were 7.77, 0.03% and $0.52ds.m^{-1}$, indigenous woody plant of the mean pH, NaCl and EC were 7.31, 0.01%, $0.23ds.m^{-1}$. In case of naturalized herbaceous plant of the mean soil pH, NaCl and EC were 7.12, 0.01%, $0.29ds.m^{-1}$, naturalized woody plant of the mean soil pH, NaCl and EC were 7.34, 0.01%, $0.20ds.m^{-1}$ respectively. On average, naturalize plants showed in low salinity concentration than indigenous plants.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.1
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• pp.61-68
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• 1991

Thirty Bradyrhizobium japonicum isolates (10 strains per each soil) from 1 uncultivated [Sangnam(Soil 1), Milyang]- and 2 cultivated [Dong(Soil 2)and Chinbuk(Soil 3), Changweon] upland soils in Yeongnam area were evaluated on their symbiotic effectiveness to soybean [Glycin max (L.)] cv. Korean Jangbaekkong and American Clark and examined on their serological diversity. The results obtained were summarized as follows : 1. On symbiotic effectiveness of B. japonicum with plant genotypes, isolates showed a relatively high value of nodule mass in Jangbaekkong cv. and of shoot dry weight and total nitrogen in Clark cv. demonstrating the order of Soil 1> Soil 2> Soil 3 isolates. 2. Among 30 B. japonicum isolates, YCK 141 showed the best effectiveness on mean nitrogen fixation of two cultivars. 3. Thirty indigenous B. japonicum showed 6 types of serological diversities in the immunoblot analysis which were present in various proportions at Soil 2(5) and Soil 3(5) except Soil 1 where all isolates fell into the YCK 117 serogroup. And their distribution order was serotype YCK 117( 12 strains) > USDA 1l0(5strains), USDA 123(5 strains) > YCK 150(4 strains) > YCK 141(3 strains) > YCK 226(1 strain). 4. Especially, 10 isolates from Soil 1, an uncultivated orchard, showed a very homologous pattern in not only effectiveness but serological distribution. It seemed to indicate that the isolates were typically affected by numerous physical and environmental factors of the soil.

• Korean Journal of Agricultural Science
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• v.5 no.2
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• pp.136-144
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• 1978

A series of experiments over three years was planned for practical application of rhizobia in farms and grass lands in Korea. This is the report for the studies of the first year mainly on the isolation and characterization of rhizobial strains, and on the assessment of their nodulation abilities and nitrogen fixation capacities. 1. Total number of 88 strains for soybean group and 22 st ra ins for pea and vetch group was isolated from nodules which were taken from legumes grown in Daekwanyong, Cheju and various places in Korea. 2. Morphological and cultural characteristics of the strains were studied, and attempts were also made to investigate their antigenic properties and to demonstrate lysogenic strains in these groups. The results were : i) the isolates varied in cultural characteristics on yeast mannitol broth and agar, and in degree of congo reel absorption ; ii) similarities in their antigenic properties were found between/among the strains: G-3/G-9/D216, G-20/G-52 in soybean group; iii) no lysogeny was found in the strains of these groups. 3. Plant infection tests by test tube and bottle method in light room were carried out to elucidate the ability of the strains to nodulate specific legumes and of the capacity of such nodules to fix atmospheric nitrogen. The isolates were grouped into non- invasive, ineffective, or effective to the legumes. Those strains which produced effective nodules, supporting similar level of growth as nitrate control, were: P-3, 4 and 8 in pea and vetch group; G-23, 27, and, D-216 in soybean group.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.2
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• pp.114-123
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• 2009

To investigate the possible use of plants for landscaping in reclaimed soil, a planting pilot system experiment was performed over the course of four years in reclaimed dredging area with four species: Alnus firma, Alnus hirsuta, Pinus thunbergii, and Pyrachantha angustifolia for 4 years. The physicochemical characteristics of the tested soil showed that it was sandy through coming from a reclaimed dredging area. The average pH of the tested soil was 7.16(slight alkali), and electric conductivity(EC) was relatively low, $294{\mu}S/cm$, even though it came from a saltwater area. To test the effect of planting density vs. phytomass by plant specie from a planting basin, the experiment was designed using four plant species with high and low planting densities over 4 years. The planting conditions of the growth of landscape tree species exhibited growth height as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia, whill the DBH followed the order of A. hirsuta, A. firma, and P. thunbergii. The total phytomass of each plant was higher at low density planting areas than high density planting area in terms of total phytomass production and growth distribution in the reclaimed dredging area. Total phytomass per unit area increased as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia. The total phytomass per each tested plant was 2 times higher in low density planting areas than high density planting areas. Total phytomass per unit area, however, was similar or slighty higher in high density planting areas compared to low density areas. Among the tested plants, A. hirsuta showed the highest phytomass, implying that A. hirsuta adapted very well to the reclaimed area and has the capability of a fast growth, nitrogen fixation tree, and utilizing insoluble nutrients through inoculated root nodule bacteria. The yield of phytomass per individual in low density Alnus species was greater than that of the high density. However, those per unit areas had no difference in the density-dependent planting. The ratio of belowground to aboveground was $0.21{\sim}0.26$. Thus, it could be concluded that the Alnus species are potential candidates for ornamental tree species in reclaimed dredging areas. This study offers baseline data for the use of ornamental tree species in reclaimed dredging areas. Additional research is required for different ornamental species in order to increase phytomass of a planting conditions based on reclaimed dredging areas.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.391-396
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• 2010

In this research the characteristics of ammonia removal from malodorous waste-air were investigated under various operating condition of biofiilter packed with equal volume of rubber media and compost for the efficient removal of ammonia, representative source of malodor frequently generated at compost manufacturing factory and publicly owned facilities. Then the optimum conditions were constructed to treat waste-air containing ammonia with biofilter. Biofilter was run for 30 days(experimental frequency of 2 times/day makes 60 experimental times.) with the ammonia loading from $2.18g-N/m^3/h$ to $70g-N/m^3/h$ at $30^{\circ}C$. The ammonia removal efficiency reached almost 100% for I through IV stage of run to degrade up to the ammonia loading of $17g-N/m^3/h$. However the removal efficiency dropped to 80% when ammonia loading increased to $35g-N/m^3/h$, which makes the elimination capacity of ammonia $28g-N/m^3/h$ for V stage of run. However, the removal efficiency remained 80% and the maximum elimination capacity reached $55g-N/m^3/h$ when ammonia loading was doubled $70g-N/m^3/h$ for VI stage of run. Thus the maximum elimination capacity exceeded $1,200g-N/m^3/day$(i.e., $50g-N/m^3/h$) of the experiment of biofilter packed with rock wool inoculated with night soil sludge by Kim et al.. However, the critical loading did not exceed $810g-N/m^3/day$ (i.e., $33.75g-N/m^3/h$) of the biofilter experiment by Kim et al.. The reason to exceed the maximum elimination capacity of Kim et al. may be attributed to that the rubber media used as biofilter packing material provide the better environment for the fixation of nitrifying and denitrification bacteria to its surface coated with coconut based-activated carbon powder and well-developed inner-pores, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.131-140
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• 2015

To set up unicellular cyanobacterial strains with photo-biological $H_2$ production potential, live samples were repeatedly collected from 68 stations in the coastal zone of Korea for the four years since 2005. Among 77 cyanobacterial strains established six (KNU strains, CB-MAL002, 026, 031, 054, 055 and 058) were finally chosen as the excellent strains for $H_2$ production with $H_2$ accumulation over 0.15 mL $H_2\;mL^{-1}$ under general basic $H_2$ production conditions as well as positive $H_2$ production for more than 60 hr. To explore optimum procedures for higher $H_2$ production efficiency of the six cyanobacterial strains, the inter-strain differences in the growth rate under the gradients of water temperature and salinity were investigated. The maximum daily growth rates of the six strains ranged from 1.78 to 2.08, and all of them exhibited $N_2-fixation$ ability. Based on the similarity of the 16S rRNA sequences, all the test strains were quite close to Cyanothece sp. ATCC51142 (99%). The six strains, however, were grouped into separate clades from strain ATCC51142 in the molecular phylogeny diagram. Chlorophyll- a content was 3.4~7.8% of the total dried weight, and the phycoerythrin and phycocyanin contents were half of those in the Atlantic strain, Synechococcus sp. Miami BG03511. The growth of the six strains was significantly suppressed at temperatures above the optimal range, $30{\sim}35^{\circ}C$, to be nearly stopped at $40^{\circ}C$. The growth was not inhibited by high salinities of 30 psu salinity in all the strains while strain CB055 maintained its high growth rate at low salinities down to 15 psu. The euryhaline strains like CB055 might support massive biotechnological cultivation systems using natural basal seawater in temperate latitudes. base seawater. The biological and ecophysiological characteristics of the test strains may contribute to designing the optimal procedures for photo-biological $H_2$ production by unicellular cyanobacteria.