• Journal of the Korean Geotechnical Society
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• v.28 no.11
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• pp.79-86
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• 2012

Cemented soils have been used for subbase or base materials of roads, backfill materials of retaining walls and cofferdam. Such cemented soils can be degraded due to repeated wetting and drying or various weathering actions. Unlike rocks, a standard method was not defined for evaluating the durability of cemented soils. In this study, a slaking durability test and an ultrasound cleaner were used for developing a new durability test method for cemented soils. For durability tests, cemented sands with different cement ratios (4, 6, 8, and 12%) with cylindrical specimens were prepared and then air cured or under-water cured for three days. Three-day-cured specimens were dried for one day and then submerged for one day before testing. The weight loss after the slake durability test or ultrasonic cleaner operation for 10 or 20 min was measured and used for assessing durability. When a cement ratio was 4%, the weight loss from ultrasonic cleaner test was 7-25% but that from slake durability test was as much as 30-60%. For specimens with cement ratio of more than 8%, the weight loss was less than 10% from both tests. A durability index increased with increasing a cement ratio. The durability index of under-water cured specimen was higher than that of air cured specimen. The ultrasonic cleaner test was found to be an effective tool for durability assessment of cemented sands rather than the slake durability test.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.2
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• pp.73-95
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• 2023

The purpose of this study is to analyze the industrial structural changes and types of specialized in the shipbuilding cities, which are representative sectors of industrial city decline, and explore regional responses. Most cities designated as special areas for industrial crisis response in 2018 are specialized in shipbuilding. While the shift from prosperity to recession since the 2010s is the main factor, each city has responded differently to the industrial crisis. The analysis, targeting seven shipbuilding cities, shows that regions where large shipyards of major corporations with high industrial competitiveness are located have relatively less decline during business fluctuations, and there is a tendency for a decrease in industrial structural diversity during prosperous periods and an increase during recessionary periods. Based on the resistance and recoverability to industrial crises, the industrial paths of shipbuilding cities are classified into four types. Considering regional industrial structure and competitiveness, it is necessary to develop customized support strategies such as maintaining and declining shipbuilding industries and fostering new alternative industries.

• Korean Journal of Plant Resources
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• v.32 no.2
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• pp.124-143
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• 2019

This study was carried out to build a database system for amylose and protein contents of rice germplasm based on NIRS (Near-Infrared Reflectance Spectroscopy) analysis data. The average waxy type amylose contents was 8.7% in landrace, variety and weed type, whereas 10.3% in breeding line. In common rice, the average amylose contents was 22.3% for landrace, 22.7% for variety, 23.6% for weed type and 24.2% for breeding line. Waxy type resources comprised of 5% of the total germplasm collections, whereas low, intermediate and high amylose content resources share 5.5%, 20.5% and 69.0% of total germplasm collections, respectively. The average percent of protein contents was 8.2 for landrace, 8.0 for variety, and 7.9 for weed type and breeding line. The average Variability Index Value was 0.62 in waxy rice, 0.80 in common rice, and 0.51 in protein contents. The accession ratio in arbitrary ranges of landrace was 0.45 in amylose contents ranging from 6.4 to 8.7%, and 0.26 in protein ranging from 7.3 to 8.2%. In the variety, it was 0.32 in amylose ranging from 20.1 to 22.7%, and 0.51 in protein ranging from 6.1 to 8.3%. And also, weed type was 0.67 in amylose ranging from 6.6 to 9.7%, and 0.33 in protein ranging from 7.0 to 7.9%, whereas, in breeding line it was 0.47 in amylose ranging from 10.0 to 12.0%, and 0.26 in protein ranging from 7.0 to 7.9%. These results could be helpful to build database programming system for germplasm management.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.183-192
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• 2011

In recent years there has been an increasing focus on global warming and the exhaustion of resources caused by the heavy consumption of fossil fuels. In order to resolve these issues, biomass has gained much attention as a source of renewable energy. One area of particular interest has been the production of biodiesel. The biodiesel produced by the transesterification of vegetable oils, animal fats and waste cooking oils is expected to be one of the eco-friendly biomass-based alternatives to fossil fuels. This paper reviews some of the recent findings for the effective biodiesel production system, together with several factors affecting the biodiesel yield.

• The Korean Journal of Ecology
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• v.27 no.5
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• pp.257-261
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• 2004

Juniperus chinensis var. sargentii Henry is a short and creeping evergreen shrub which reaches about 50㎝ in height and occurs in the northeast Asia and in high mountains over the South Korea. Its distribution is restricted, and the number of individuals are gradually decreasing. This study was conducted to estimate spatial pattern, genetic diversity and spatial genetic structure of J. chinensis var. sargentii. A total of 131 clumps were studied in the study area (40m × 60m). The spatial pattern of this population was random (Aggregation index R=1.031). In spite of the small number and the limited distribution, the level of genetic diversity (Shannon's index 1=0.463) was relatively high as compared with those of other plant species with similar ecological characteristics. ISSR genotypes of all individuals were investigated to find the genetic relationship of clumps and genets. Fifteen clumps were composed to be clones, and a total of 116 unique genotypes were composed by separate genets. Spatial autocorrelation analysis using Tanimoto distance showed that the genetic patch was established within 8m. The effect of clonal reproduction on genetic structure was almost nothing.

• Journal of Applied Biological Chemistry
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• v.56 no.2
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• pp.95-100
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• 2013

Soil microbes are important integral components of soil ecosystem which have significant and diverse role in organic matter decomposition, nitrogen cycling, and nitrogen fixation. In this study an effective denaturing gradient gel electrophoresis (DGGE) method was employed for paddy soil microbial diversity survey. For optimum paddy soil microbial DNA extraction, different methods such as Lysis buffer, skim milk bead, sodium phosphate buffer, Epicentre Soil Master DNA extraction kit (Epicentre, USA) and Mo Bio Power Soil DNA kit (MO BIO, USA) methods were utilized. Among all the method, using Mo Bio Power Soil kit was most effective. DGGE analysis of Bacteria was carried out at 6% polyacylamide gel and 45-60% denaturing gradient in the optimal conditions. Whereas DGGE analysis of fungi was done at 6% polyacrylamide gel and 45-80% denaturing gradient in the optimal conditions. By applying the above assay, it was found that variation within the microbial community of paddy soil occurs by a factor of time. DGGE assay used in this study through for a variety of soil microbial analysis suggests the potential use of this method.

• Journal of Life Science
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• v.26 no.12
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• pp.1446-1457
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• 2016

Wetlands exhibit intermediate characteristics of both terrestrial and aquatic ecosystems, and the biodiversity is rich in these unique biological habitats. The symbiotic relationships between plants and fungi that inhabit these wetlands play an important role in natural resource management, biodiversity, and conservation. Accordingly, the mujechi, having academic value for the study of the natural environment, was investigated in terms of genetic diversity of endophytic fungi, which inhabit the roots of wild plants. The internal transcribed spacer (ITS) region was amplified to identify fungal strains. In total, 226 strains were isolated and categorized into three phyla, seven classes, 10 orders, 22 families, and 31 genera. In plants by endophytic fungi were classified in Isachne globosa (Ig) to 19 genera, Scirpus karuisawensis (Sk) to 11 genera, Utricularia racemosa (Ur) to 19 genera, and one incertae sedis, Eriocaulon decemflorum (Ed) to 11 genera. The fungal taxa was identified the genera Acephala (19.9%), Tolypocladium (16.3%), Neopestalotiopsis (11.5%), and Perenniporia (7.1%). The fungal group isolated from Isachne globosa (Ig) grew the largest number of isolated fungal strains. After comprehensive evaluation, the endophytic fungal group from Utricularia racemosa (Ur) ranked highest in diversity analyses. From the roots of wild plant in mujechi-neup, it confirmed the distribution and diversity of endophytic fungi. This study provides the basic data to understand fungal community structure in peat wetlands.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.407-415
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• 2012

Pinus pumila, which occurs in the northeast Asia, is found limitedly in Daecheongbong area of Mt. Seorak in the South Korea. This population was chosen to study spatial pattern, genetic diversity and spatial genetic structure. There were 48 polymorphic and 30 monomorphic I-SSR markers. A total of 65 individuals which distributed in the study site (40 m ${\times}$ 70 m) showed weakly aggregate distribution (Aggregate Index = 0.871). A total of 40 genets were observed from 65 individuals through I-SSR genotype comparison. Proportion of distinguishable genotype (G/N), genotype diversity (D) and genotype evenness (E) were 61.5%, 0.977 and 0.909, respectively. In spite of the small number and the limited distribution, Shannon's diversity index (I = 0.567) was relatively high as compared with those of other plant species. Spatial autocorrelation using Tanimoto's distance showed that the genetic patch was established within 12 m. Based on Mantel tests, there was relatively low correlation between genetic distance and geographic distance. Therefore, it seems the P. pumila population was formed by many parent trees in early stage. For ex situ genetic conservation of P. pumila, the sampling strategy is efficient at least above 12 m between individual trees.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.315-324
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• 2016

Because of a fissility characteristics of shale in the Gyoungsang super-group, it breaks down to debris when daylighted by construction work and causes a slope unstability. To assess the durability property of shale, a series of slake durability tests was conducted by controlling test conditions such as shape of specimen, number of specimen, revolution speed, revolution number, drying temperature and pH of submerging liquid. For the specimen shape, cube one showed relatively lower durability index than cuboid and/or fan shape one. The test with the more number of specimens showed the less durability index because of a higher friction among specimens in the drum. The durability index is linearly decreased by increasing the total number of revolution, while the revolution velocity could not affect the index. And the durability index is also decreased by increasing the drying temperature of specimen and by decreasing the pH of submerging liquid. Because the durability index of shale is almost similar to that of crystalline rocks, the disintegration characteristics of shale could not be assessed by the slake durability test recommended by ISRM, and thus a new test method by changing the total revolution number may be required for the shale having fissility characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.1
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• pp.70-78
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• 1991

Both long period of summer drought and unusual high water temperature in 1988 caused the harmfull effect to the aquacultural organisms in south coast of Korea. One of those was the mass mortality of arkshell seedlings in Jinhae Bay. The purpose of this study was to verify the effects of environmental factors on arkshell seedlings by investigating not only water quality and food organisms in culturing grounds, but also meteorological conditions. Water temperature in November was higher at $2.0^{\circ}C$ than mean water temperature and the concentration of total inorganic nitrogen and N/P ratio were $0.38{\mu}g-at/l,$ 0.98, respectively which indicated the exhaustion of nutrients, especially nitrogen in the study area. In analysis of phytoplankton population structure, species diversity index(H) , equitability-index(e), species richness $index(d_1)$ were low, but dominance $index({\delta}_2)$ was high at the value of 98.4 and dominant species was Nitzschia pungens. In conclusion, it seems that mass .mortality of arkshell seedlings in November was resulted from the metabolism disorder with poor food organism under the unstable marine environment.