• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.157-165
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• 2020

At present, there are no clearly stated criteria or theories in calculating additional vertical dynamic loads that occur at the machine foundation due to vibration and reflecting them in the design at home and abroad. According to the domestic standard, although it is not a serious vibration condition, the additional dynamic load due to vibration is considered up to 100% of the static load. This is an extremely conservative design. The purpose of this study is to propose a model test method for evaluating the quantitative magnitude of additional dynamic loads that are generated at certain static loads due to vertical mechanical vibrations. As preliminary basic tests for the model tests, the test for evaluating the effects of reflective wave that may occur within a limited size soil box and the test for estimating the natural frequency of the devised model soil-foundation system were carried out. From the analysis of results for basic tests, a method to minimize the influence of the reflected wave was prepared, and the effect of the resonance of the model system was minimized during the model tests. After the basic tests, the main model tests were conducted. Through the proposed main test, the quantitative magnitude of additional dynamic loads caused by machine vibration on a shallow foundation for machine on medium dense sand foundations were evaluated. From the results of the model test, the feasibility of design applied at home and abroad was reviewed.

• Korean Journal of Environment and Ecology
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• v.16 no.1
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• pp.22-33
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• 2002

This study was conducted to investigate the effects of fragmentation on the bird community in Seongduck-ri and Hanggum-ri agricultural landscapes of Kangha-myon, Yangpyong-gun, Kyonggido. We analyzed the composition of tree species, forest environmental structures, structures of agricultural landscapes, avifaunas and guild structures. Number and density of tree species ranging from 6 to 10cm in D.B.H. were high in Seongduck-ri, but basal area was high in Hanggum-ri. Coverages of foliage layers under two meters and over 12 meters were high in Hanggum-ri. Meanwhile, Seongduck-ri agricultural landscapes consisted of twelve patches, dominated by Larix leptolepsis and Robinia pseudoacacia Hanggum-ri landscapes was composed of eleven patches, and dominated by Pinus rigida, Castanea crenate, Larix leptolepsis and paddy field. Dominant bird species showed the same order in two study areas, thirty-six species of birds were observed in Hanggum-ri landscapes, but twenty species were in Seongduck-ri landscapes. Number of species and density belonging to hole-, bush-, ground-nesting and water-, bush-, ground-foraging guild were high in Hanggum-ri landscapes. Number of species and density belonging to hole-nesting guild showed the high value in Hanggum-ri landscapes that was not fragmented. It could be attributed to the low human disturbance and relative high density of medium and large trees in D.B.H. Also, number of species and density belonging to bush-, ground- and water- foraging guild showed the high value in Hanggum-ri landscapes that had the high foliage amounts in the foliage layer under two meters. It will be related with the paddy field, dry field and brook, which patches covered the 28.4% of Hanggum-ri landscapes. Therefore, road not only dominate the heterogeneous patch in agricultural landscapes, but also easily cause the human disturbance. Thus, road construction would decrease the natural patch diversity and edge effects that are important for sustaining the diverse avifauna in agricultural landscapes.

• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.3
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• pp.22-33
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• 2020

Sign system is one of the most widely used guide media in scenic spots. It plays vital role in introducing cultural values of destinations to tourists with better visit experience. The purpose of this study is to derive the influence factors of the sign system of Mount Tai scenic area for tourists, analyze the satisfaction of tourists, and provide suggestions for the sign system of Mount Tai Mountaineering Road to improve tourists' satisfaction in the future. The evaluation items of Mount Tai Mountaineering Road sign system were derived from the previous studies and then subdivided comprehensively. Survey by questionnaires was carried out to obtain the influence factors. In order to understand the satisfaction degree of tourists, fuzzy comprehensive evaluation was implemented. The research results of this study are summarized as follows. First, four influence factors of the sign system on Mountaineering Road of Mount Tai were concluded as the interpretation content, appearance modeling, interpretation methods and layout management. Second, the order of weight values of influence factors was the interpretation content, appearance modeling, interpretation methods and layout management respectively from high to low, which means that tourists paid more attention to practicality and aesthetics. Third, the satisfaction degree of the tourists on the sign system was different. The satisfaction level for the three factors (interpretation content, appearance modeling, layout management) was good, while the satisfaction for interpretation method was medium. The reason was that it failed to deepen the understanding of tourists on the natural and cultural values of Mount Tai Mountaineering Road. These results indicate great significance to provide theoretical basis for the later readjustment and design of the sign system and to improve the overall satisfaction of tourists on tourism experience.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.456-464
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• 2016

Korea established an inventory of 1,916 sites of inland wetlands during a nationwide investigation from 2000 to 2010. If inland wetlands is included in or near various protected areas designated by the government, it can be selected as a wetland to be managed with priority. This study evaluated the aspect of management of inland wetlands by analyzing the correlation between locations of national protected areas and inland wetlands. As a result, it was shown that a considerable percentage of current inland wetland was located in areas that were designated and managed as protected areas by the government, as they had a high value of natural environment protection (527 sites, 31.61 %). When the range was widened to a radius of 1 km for protected areas, 959 sites were included and 57.53 % of sites were located in or nearby the protected areas. Among them, 46.79 % of sites were distributed up to or within a 1 km radius of waterside areas and rivers; it accounted for 81.33 % of wetlands located in protected areas. Therefore, it was found that locations of current inland wetlands were mostly in contact with rivers. The results of overlay analysis were classified into high, medium and low; the correlation of location with inland wetlands was analyzed through the analysis of separation distance of various protected areas. The number of wetlands located in areas of a 'high' value of protection was 998 (59.87 %); 289 sites (17.34 %) were distributed in areas of a 'low' value of protection. This implies that these wetlands are located in artificial areas and are more exposed to environmental pressures. Thus, these wetlands could be determined as inland wetlands, which we considered for the establishment of measures to prevent damage.

• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.171-177
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• 2017

A callus-mediated regeneration protocol for sea-milkwort, an endangered coastal plant species in South Korea, is reported here. The explants of in vitro-plantlets generated from a node culture revealed distinguishable responses in callus induction depending on genotype, explant source, light condition, and 2,4-D concentration. Especially, continuous darkness exclusively facilitated callus induction from explants prior to other treatments. The calli initiated on the media with 2,4-D ranging from 0.1 mg/L to 3.0 mg/L in the dark vigorously proliferated when subcultured on the same media in continuous darkness. Given 1.0 mg/L zeatin in addition to darkness to the calli of the 'Pistachio' genotype, normal adventitious shoots were only regenerated from nodular structures that formed earlier from the calli at the frequency of 24.4 percent. Regenerated shoots easily grew into plantlets with roots and green color on a phytohormone-free MS medium under lighted condition, that were used for node culture as plant materials. Node culture effectively multiplied plantlets in accordance with protocol by Bae et al. (2016). Acclimatized plantlet clusters developed mature plant clusters under inland environment, followed by flowering the following April. Results were merged with node culture protocol suggested by Bae et al. (2016), which, as an in vitro propagation system for sea-milkwort, may contribute to natural habitat restoration.

• The Journal of the Petrological Society of Korea
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• v.27 no.3
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• pp.121-138
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• 2018

We have examined the petrotectonic setting and magmatic evolution from petrochemical characteristics of major and trace elements for the Cretaceous volcanic rocks in and around the Mireukdo Island. The volcanic rocks, can be devided into Jusasan, Unmunsa, Yokji and Saryang subgroups on the ascending order, are classified as basalt, basaltic andesite, andesite, dacite and rhyolite on TAS diagram. Petrochemical data show that the rocks are calc-alkaline series, and suggest that erupted earlier medium-K series and later high-K series. The volcanic rocks provide a case in which the calc-alkaline magma are formed, not only from separate protoliths, but following separate paths from source to surface. Earlier and later subgroups take different paths to the surface respectively, and are emplaced in the shallow crust as a series of discrete magma chambers through the volcanic processes. After emplacement, each chamber evolves indepently through fractional crystallization with a little assimilation of wall rock. The volcanic rocks have close petrotectonic affinities with orogenic suite and subduction-related volcanic arc. The rhyolitic magma can be derived from calc-alkaline andesitic magma by fractional crystallization with crustal assimilation, which may be derived from a partial melt of peridotite in the upper mantle.

• Journal of Life Science
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• v.28 no.8
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• pp.955-961
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• 2018

Although much research has focused on various bioactive substances in starfish, research on microorganisms isolated from starfish is lacking as compared with other natural products. In this study, we investigated bacterial communities in the gut of red starfish (Certonardoa semiregularis) in Jeju Island. In total, 103 bacterial strains were isolated using marine agar and R2A medium. The isolated strains were analyzed and identified using the 16S rRNA gene sequence. Based on an analysis of this gene sequence, the 103 isolated bacteria were classified into four major groups: Proteobacteria (93%: Alpha-proteobacteria, 24.8%; Beta-proteobacteria, 4%; Gammaproteobacteria, 65%) Bacteroidetes (4%), Actinobacteria (2%), and Firmicutes (1%). In addition, the isolates were divided into seven classes (Actinobacteria, Flavobacteria, Bacilli, Sphingobacteria, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria), 15 orders, 19 families, and 24 genera. A phylogenetic analysis revealed two strains, Lysobacter sp. and Pedobacter sp., with similarity of 97.55% and 97.58%, respectively. As the similarity in the 16S rRNA gene sequence was 98% or less compared to previously identified bacteria, the two strains may possibly be classified as a new genus or species. We suggest that additional studies, including biochemical and morphological tests, should be performed to identify the new candidate strains.

• Journal of Wetlands Research
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• v.22 no.1
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• pp.31-38
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• 2020

Weirs are to secure amount water of streams and drop structures are to enhance stabilization of stream bed and bridges are to connect isolated region, which are called stream crossing structures. In the stream design criteria, directions for minimum size of structures are suggested to secure stability of stream crossing structures. However the sizes of almost all existing weirs and drop structures are not satisfied with the stream design criteria and only 22 percent of the peirs of bridges are satisfied. To enhance hydraulic stability of existing weirs and drop structures, it is required that the ratio of bed protection to apron should be above 3.3. According to factual survey of structures in the sample streams, it has been shown that the longitudinal slope of rapid works with 1:20 is the most reasonable to design velocity if existing weirs and drop structures are rehabilitated into rapid works. It has been known that violating freeboard and span length of piers should make existing bridges reconstructed or removed. However, comprehensive review including deterioration level of bridges, special regulation for span length, etc. should be considered to determine rehabilitation plan of bridges. In this study, a procedure has been suggested to improve hydraulic stability of weirs, drop structures and piers of bridges. Sound environment of stream and reduction of natural disaster could be achieved by improving stability of cross structures, which could be obtained by governmental budget and active stream management including observance of design criteria.

• Development and Reproduction
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• v.12 no.2
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• pp.125-132
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• 2008

Melatonin (N-acetyl-5-methoxytryptamine), a major hormone of pineal gland in vertebrates, is known to be associated with regulation of the dynamic physiological functions in general and has some functions on reproduction in the ovarian follicles in particular. And its antioxidant properties as a scavenger are also reported. The aim of this study was to investigate the effect of melatonin on the in vitro maturation of mouse germinal vesicle (GV)-stage oocytes. Oocyte maturation, apoptosis, and mRNA expression of melatonin receptor were analyzed in the cumulus cell-enclosed oocytes (CEOs) cultured with melatonin for 18 h. The CEOs were obtained from 3 wk-old ICR female mice cultured in media with 0, 0.1 nM, 10 nM, or 1,000 nM melatonin for 18 h. And then the extrusion of the first polar body was assessed to evaluate the maturation rate. The apoptosis and mRNA expression of melatonin receptor (Mtnr1-a and Mtnr1-b) in cumulus cells of each group were measured by TUNEL assay, ELISA, and real time RT-PCR after in vitro maturation(IVM). The addition of melatonin in the IVM medium significantly improved nuclear maturation of the mouse GV oocytes and the highest maturation rate were obtained from the group treated with 1,000 nM melatonin. Apoptosis was not detected in IVM oocytes, but detected in cumulus cells. And cumulus cells treated with 1,000 nM melatonin exhibited significantly lower apoptosis. In the group treated with 1,000 nM melatonin, the expression of melatonin receptor mRNA was decreased in CEOs. In conclusion, melatonin has a potentially important role for regulating oocyte maturation and reduces the apoptosis of cumulus cells in vitro.

• Korean Journal of Medicinal Crop Science
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• v.14 no.3
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• pp.153-157
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• 2006

Floret flowering of Orostachys japonicus, a monocarpic and short day plant, should be controlled to continue cultivating. The study was done to examine the effect of transplanted seedling size (large, 18 leaves; medium, 13 leaves; small, 8 leaves) on growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done on August 25 and afterward samples were taken every 2 weeks. Growth, morphological and flowering related characters were measured from each sample. With larger seedling transplanted, plant height, inflorescence length, number of leaves including bracts and stem diameter were increased. Leaves and bracts, stem, root, shoot and total dry weights were increased as transplanted seedlings became larger. Although formed florets were inclined with larger transplanted seedling, they were not flowered because of the night-break treatment, meaning that the larger transplanted seedlings, the more economic yield.