• Journal of Microbiology
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• v.45 no.2
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• pp.122-127
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• 2007

Factors indicating culture status of two Spirulina platensis strains were monitored in a batch mode cultivation for 36 days. Changing mode in all factors showed a common turning point, indicating shift of cell or culture status. Mean biomass productivity was highly sustained until day 22, chlorophyll a concentration peaked on day 22, pH value was > 12 on day 22, coil number was abruptly shortened on day 22, and floating activity was sustained at greater than 79% after day 22, indicating that day 22 is a criterion reflecting phase-transfer in cell physiology in a batch culture system. Many of these changes may have been caused by increased pH, suggesting that pH control is essential for mass production of S. platensis. Fluctuations in floating activity were likely induced by the number of cellular gas vacuoles. Consequently, coil number per trichome and floating activity of S. platensis could readily act as simple indicators for determination of culture status or harvesting time of cells.

• ALGAE
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• v.21 no.1
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• pp.133-139
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• 2006

Outdoor cultivation of cyanobacterium Spirulina platensis was carried out for 40 days in a batch mode. A half concentration of the SOT based on the underground water was used as culture medium. Working volume was 5.7 tons with 0.2 m depth. During cultivation, mean water temperature, DO and light intensity were all in proper conditions for the S. platensis growth. The adjustment of pH to over 10 with Na2CO3 and addition of the 1.5% natural salt were very effective to delete contaminant organisms, Chlamydomonas moewusii and Chlorella minutissima occurred one after the other in the culture. The mean productivity of the biomass based on the dry cell weight from 14 to 25 days, after the contaminants were deleted, was 7.8 g ·m–2· d–1, which was relatively high productivity in that a half concentration of the SOT was used for the culture. Underground water used in the culture minimized contaminants invasion and addition of the 1.5% natural salt was effective to delete contaminants as well as acted as mineral supplement in outdoor cultivation of S. platensis. Harvesting using the floating activity of S. platensis was effective from mass floating in day time after overnight without agitation and illumination.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.45-58
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• 2015

The aim of this study is to find out major accumulation zones through field survey and moving route tracking trials on floating debris of Nakdong River. It also identified composition and accumulated amount of the floating debris by sample survey for accumulation zones. As a result, total 5 accumulation zones were selected from the midstream and downstream of the Nakdong River. There was a large amount of floating debris, including vegetation debris, in the accumulation zones. And two accumulation zones located in the downstream region, it is much more likely to flow into the ocean along river. From the sample survey on the major accumulation zones, more than $40{\ell}$ of floating debris were collected including vegetation and artificial debris. As a result of composition analysis for artificial debris, plastic(49%) and styrofoam(36%) were the majority in number. The present study is expected to help to plan an efficient pre-collecting activity and to reduce floating debris flowing into the ocean from the Nakdong River.

• Journal of Microbiology and Biotechnology
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• v.7 no.4
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• pp.267-271
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• 1997

We developed a dermal equivalent (DE) which was engineered using human dermal fibroblasts and a matrix of collagen gel. The in vitro construction of the DE was accomplished by casting a porcine collagen type I solution plus concentrated medium with isolated and cultured fibroblasts. These constructs were attached to culture dishes or left floating in culture medium. Contraction of attached gels results in decreased gel thickness without a change in gel diameter, and contraction of floating gels results in decreased gel thickness and diameter. After contraction, there was no increase in cell number in floating gels, but cells in attached gels began to increase after about 4 days of the lag phase in cell growth curve. At this lag phase, addition of fibroblast growth factor (FGF) at a concentration of $0.1{\mu}$/ml promoted cell proliferation in the attached collagen gels, but no effect in floating gels. These results indicate that the method of contraction had an influence on the extracellular matrix (ECM) organization, and this influenced not only cell growth but also fibroblast responsiveness to FGF. This suggests that attached collagen gel is more suitable as a dermal equivalent than the floating gel. And the final contracted area of attached gel is much larger than that of the floating gel since floating gel is contracted in all directions but attached gel is contracted only vertically.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.102-111
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• 1998

Ocean monitoring facilities are divided into two types, fixed type and floating type. This paper deals with wane load calculation and mooring system for a floating monitoring facility. Wave load and drift forces are calculated for an example case of floating monitoring buoy To enlarge holding power of anchor, circular pile model test was performed. A program for horizontal force of circular pile in sand was made and the calculated result showed fairy good agreement with the result of model test. It is expected that this method will provide good estimation for the holding power of the prototype of circular pile anchor which is relied upon SCUBA activity for installation.

• The Research Journal of the Costume Culture
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• v.22 no.1
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• pp.112-125
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• 2014

The purpose of this study was to compare the effects of internet fashion advertisement (Ad) formats according to university students' online lifestyle. Static banner, rich media, floating, shopping, and target advertisement were selected as stimuli and a self-administered questionnaire was used for data collection. SPSS PC (Ver. 16.0) was used for factor analysis, ANOVA, and Chi-square test. Factors of online lifestyle were economy, early adaption, cyberspace activity, sociability, innovation, and entertainment, and subjects were segmented into online activity (OA) retard group, OA mania group, hedonic early adapter group, and OA intermediate group. OA retard group was positive to a static banner Ad with intimacy, and OA mania group and OA intermediate group were positive to a static banner Ad with confidence, attention, and intimacy and rich media Ad and floating Ad with confidence and attention. Hedonic early adapter group was positive to a target Ad with attention and intimacy. Internet shopping mall managers should select internet Ad format after segmenting their customers according to OA lifestyle.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.3
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• pp.43-50
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• 2004

This study looked into the water quality improvement effect of reed (Phragmites communis), bur reed (Sparaganium stoloniferum), Alisma canaliculatum, and Hydrocharis dubia in order to develop native hydrophytes suitable to natural-type wetlands for ecological restoration. The result confirms that the concentration of wastewater was lowered in most plants indicating a possibility in wastewater treatment. Among four species, reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were most effective in removing a majority of contaminants. Considering that reed (Phragmites communis) is a species that has been used most often among hydrophytes, bur reed (Sparaganium stoloniferum), which is a native species in Korea, showed equivalent level of outstanding effect. In the physiological and growing activity and its relations to water quality improvement effect, each species appeared differently. Reed (Phragmites communis) and bur reed (Sparaganium stoloniferum) were best also in physiological and growing activity. In the case of Hydrocharis dubia, growth was strong in polluted water environment but its physiological activity was poor, indicating that it was under stress. The growth and physiological activity of Alisma canaliculatum were also poor, indicating that it too is being stressed. However, measuring organic contents in the plants of each species shows that the organic contents of Alisma canaliculatum was high. Alisma canaliculatum is a species effective in removing pollutants in water, although it is under stress. A unique phenomenon in removing water pollution with plants is that each species removed different pollutants. In the case of Alisma canaliculatum, which was relatively poor in removing pollution, it was remarkable in reducing nitrogen and phosphorus. Hydrocharis dubia was also effective in eliminating floating matter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1150-1158
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• 2010

In this paper, a new reliable portable activity monitoring device implemented with the buddhist-style bowing activity and walking step detection algorithm, is presented. In order to monitor the bowing and walking activities, miniaturized 3-axis accelerometer sensor with the sensitivity of 800 mV/g was used. After initial signal conditioning, vector magnitude of accelerometer signals was calculated. Syntactic peak detection method was used in order to feature points. All signal processing algorithms were implemented in ultra-low power microcontroller MSP430 with double precision floating point arithmetic. For evaluation, 19 young man($24.22\pm5.22$ yrs) and woman($22.28\pm2.72$ yrs) were involved. The accuracy of the proposed algorithms were 98.91 %($\pm0.011$) for walking step detection and 98.25 %($\pm0.023$) for buddhist-style bowing activity. Comparing to the commercialized pedometer accuracy, 87.1 %($\pm0.058$), the proposed walking step detection algorithms show more reliable accuracy.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.19-25
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• 2008

To evaluate the functions of vegetation mat of artificial floating island (AFI) installed in Lake Paldang, nutrients, such as total phosphorus (TP), dissolved inorganic phosphorus (DIP), total nitrogen (TN) and nitrate $(NO_3)$ and microbial factors such as total bacterial numbers, active bacterial numbers and exoenzymatic activities of $\beta$-glucosidase and phosphatase in pore water of medium and bulk lake water were analyzed. The concentration of TN and $NO_3$ in pore water ranged from 4.4 to 7.5mg $L^{-1}$ from 1.2 to 3.8mg $L^{-1}$ respectively, which were ca. 2 times higher than those of lake water. The ranges of TP and DIP of were $1.4\sim4.1mg\;L^{-1}$ and $0.003\sim0.137mg\;L^{-1}$ in pore water of media which were $4\sim25$ and 5 times higher than those of lake water, respectively. The numbers of total bacteria and active bacteria in pore waterwere about 10 times higher than those of laker water. Also, both phosphatase and $\beta$-glucosidase activities of pore water were on an average 10 times higher than those of lake water. These results suggest that the bacteria were playing important role for nutrients concentrating and cycling in media of artificial floating island. And the medium of artificial floating island contained newly created microbial ecosystem, which is responsible for sustaining the growth of macrophytes and the creation of new aquatic ecosystem.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.155-163
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• 2024

As the demand for reducing carbon emissions increases, efforts to reduce the usage of fossil fuels and research on renewable energy are also increasing. Among the various renewable energy harvesting techniques, the floating offshore wind turbine has several advantages. Compared to other technologies, it has fewer installation limitations due to interference with human activity. Additionally, a large wind turbine farm can be constructed in the open ocean. Therefore, it is important to conduct motion analysis of floating offshore wind turbines in waves during the initial stage of conceptual design. In this study, a frequency motion analysis was conducted on a semi-submersible type floating offshore wind turbine. The analysis focused on the effects of varying trim on the motion characteristics. Specifically, motion response analysis was performed on heave, roll, and pitch. Natural period analysis confirmed that changing the trim angle did not significantly affect the heave and pitch motions, but it did have a regular impact on the roll motion.