• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.412-421
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• 2008

Nutrient limitation was examined for the Dongbak Lake based on bioassay experiments and analyses of long-term monitoring data. From the results of data analyses, molar ratios of TN/TP and DIN/DIP were higher than 16 : 1 suggesting that phytoplankton growth was potentially limited by phosphorus. Phytoplankton responded to the addition of phosphates in the incubation experiments for all seasons whereas phytoplankton did not respond to other nutrients such as ammonia, nitrate and silicates. Size fraction (net and nano size) of phytoplankton also responded to the addition of phosphorus indicating that phytoplankton growth was limited by phosphorus in the Dongbok Lake. There was also a taxonomic shift from euglenophyceae to bacillariophyceae after addition of phosphate during warm season especially.

• Journal of Environmental Science International
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• v.19 no.5
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• pp.607-615
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• 2010

We investigated the temporal variations of heterotrophic dinoflagellates (hereafter HDNF) and photosynthetic dinoflagellates (hereafter PDNF) from 14 June to 4 September 2003 at a single station in Jangmok Bay. We took water samples 47 times from 2 depths (surface and bottom layers) at hide tide. A total of 63 species were encountered and in general the most abundant genera were Prorocentrum and Protoperidinium. The abundance of PDNF and HDNF was in the range of $0.04{\sim}55.8{\times}10^4$ cells/L and in the range of $0.01{\sim}4.35{\times}10^4$ cells/L, respectively. The mean abundance of PDNF was approximately 7 times higher than that of HDNF, and was higher in the surface layer where has enough irradiance for photosynthesis than in the bottom layer. The total dinoflagellate abundance was higher in the NLP (nitrogen limitation period) than in the SLP (silicate limitation period), and the abundance in the hypoxic conditions was similar to that in the normal conditions. The Shannon-Weaver species diversity index were slightly higher in the bottom layer, the SLP and the hypoxic conditions. The PDNF abundance were correlated with temperature, DO, total inorganic nitrogen and phosphate in the whole water column, and the HDNF abundance was significantly correlated with temperature, salinity and DO. This study shows that the dinoflagellate abundance might be affected by abiotic factors such as irradiance, temperature, salinity, DO and the concentrations of inorganic nutrients, and provides baseline information for further studies on plankton dynamics in Jangmok Bay.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.583-591
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• 1997

The functional derangement of skeletal muscles which may be attributed to chronic hypoxia has been accepted as a possible mechanism of exercise impairment in patients with chronic obstructive pulmonary disease (COPD). The metabolic changes in skeletal muscle in patients with COPD are characterized by impaired oxidative phosphorylation, early activation of anaerobic glycolysis and excessive lactate and hydrogen ion production with exercise. But the cause of exercise limitation in patients with chronic lung disease without hypoxia has not been known. In order to evaluate the change in the skeletal muscle metabolism as a possible cause of the exercise limitation in chronic lung disease patients without hypoxia, we compared the muscular metabolic data of seven male patients which had been derived from noninvasive $^{31}P$ magnetic resonance spectroscopy(MRS) with those of five age-matched normal male control persons. $^{31}P$ MRS was studied during the sustained isometric contraction of the dominant forearm flexor muscles up to the exhaustion state and the recovery period. Maximal voluntary contraction(MVC) force of the muscle was measured before the isometric exercise, and the 30% of MVC force was constantly loaded to each patient during the isometric exercise. There were no differences of intracellular pH (pHi) and inorganic phosphate/phosphocreatine(Pi/PCr) at baseline, exhaustion state and recovery period between two groups. But pHi during the exercise was lower in patients group than the control group (p < 0.05). Pi/PCr during the exercise did not show significant difference between two groups. These results suggest that the exercise limitation in chronic lung disease patients without hypoxia also could be attributed to the abnormalities in the skeletal muscle metabolism.

• Journal of Periodontal and Implant Science
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• v.37 no.1
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• pp.125-136
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• 2007

Periodontal regenerative therapy and tissue engineering on defects destructed by severe periodontitis need maintaining of space, which provides the environment for cell migration, proliferation and differentiation. Application of bone grafts may offer this environment in periodontal defects. This study evaluated bone graft materials, $MBCP^{(R)}$ and $Algipore^{(R)}$ , in surgically created i-wall periodontal intrabony defects of minipigs by histological analysis. Critical sized($4mm{\times}4mm$), one wall periodontal intrabony defects were surgically produced at the proximal aspect of mandibular premolars in either right and left jaw quadrants in four minipigs. The control group was treated with debridement alone, and experimental group was treated with debridement and $MBCP^{(R)}$ and $Algipore^{(R)}$ application. The healing processes were histologically observed after 8 weeks and the results were as follows. 1. In the control group, limited new bone formation was observed. 2. In MBCP group, more new bone formation was observed compared to other groups. 3. Histologically, dispersed mixture of new bone, biomaterial particles and connective tissue were shown and osteoblasts, osteoclasts and new vessels were present in this area. 4. Defects with Algipore showed limited new bone formation and biomaterial particles capsulated by connective tissue. 5. Histologically, lots of osteoclasts were observed around the biomaterial but relatively small numbers of osteblasts were shown. Within the limitation to this study protocol, $MBCP^{(R)}$ application in 1-wall intrabony defect enhanced new bone formation rather than $Algipore^{(R)}$ application.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.213-217
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• 2003

The effects of glucose concentration on the production of PHB by fed-batch culture of Ralstonia eutropha were investigated. In the range of glucose concentration of $2.5\;{\sim}\;40\;g/l$, it was found that the high glucose concentration was not favorable for the PHB formation after the phosphate limitation. It was further confirmed by the specific PHB synthesis rates and yields. The PHB concentration decreased much with the increase of glucose concentration. But if the glucose concentration was very low, e.g. 2.5 g/l, the cell growth and PHB synthesis also could be limited because of inadequate glucose supply. Itwould be better to maintain the glucose concentration at about 9.0 g/l to obtain high DCW, PHB concentration and productivity.

• Microbiology and Biotechnology Letters
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• v.10 no.2
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• pp.155-162
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• 1982

A cell-recycled continuous fermentation process was studied to produce ethanol from molasses using Sacchoromyces uvarum ATCC26602 at 35 $^{\circ}C$. The fermentation system was divided into two stages in order to reduce the inhibitions of ethanol and substrate for cell growth and fermentation rate. The first reactor was aerated at the rate of 0.12 vvm whilst the second was kept anaerobic. In medium composition studies, it was revealed that inorganic nutrient supplement to the diluted molasses with 14% fermentable sugar was not needed for the fermentation, however, phosphate limitation was observed when cell propagation was contemplated. By using the cell-recycled continuous fermentation system, 14.5 hour was required to produce 8.4-9.0% (v/v) of ethanol from diluted molasses containing 14% of fermentable sugar. The ethanol productivity was 6.2g/$\ell$hr with the yield of 88.1-94.4% to the theoretical value.

• Journal of Korean Dental Science
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• v.7 no.1
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• pp.1-5
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• 2014

Purpose: Capseal I and Capseal II are calcium silicate and calcium phosphate based experimental root canal sealers. This study sought to evaluate the biocompatibility and mineralization potential of Capseal I and Capseal II. Materials and Methods: The biocompatibility and mineralization related gene expression (alkaline phosphatase [ALP], bone sialoprotein [BSP], and osteocalcin) of Capseal I and Capseal II were compared using methylthiazol tetrazolium assay and reverse transcription-polymerization chain reaction analysis, respectively. The results were analyzed by Kruskal-Wallis test. A P-value of <0.05 was considered significant. Result: Both Capseal I and Capseal II were favorable in terms of biocompatibility, influencing the messenger RNA expression of ALP and BSP. Conclusion: Within the limitation of this study, Capseal is biocompatible, with mineralization promoting potential; thus, it could be a promising root canal sealer.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.221-231
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• 2009

This study was carried out to comparatively identify characteristics of turbid water influence in Imha Reservoir, Soyang Reservoir, and Daecheong Reservoir in Korea. We used 3 years dataset from 2002 to 2004 and analyzed seasonal water quality characteristics, particular parameters in association with turbidity, and light transparency to figure out the trends. All parameters to be used in the study were total phosphate (TP), total nitrogen (TN), chlorophyll-${\alpha}$ (Chl), suspended solids (SS), Secchi depth (SD), conductivity, and verticallight extinction coefficienct($K_d$), euphotic zone ($Z_{eu}$), and critical depth ($Z_p$). All parameters depend on season and watershed. Suspended solids from Soyang Reservoir were usually caused by TP, mainly related to living wastes and agricultures in upper stream. Daecheong Reservoir was influenced by organic matters related to large phytoplankton biomass in summer and inorganic suspended solids by nutrients in the winter. However, in case of Imha Reservoir, turbid water, consisted in silt and clay through heavy precipitation remained in the waterbody to decrease water transparency along with TP and caused the light limitation in winter. Overall results suggest that it was necessary to establish various management programs because the reasons occurring turbidity were varied according to the reservoir circumstances.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.245-250
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• 2013

We investigated the factors of mass-mortality in terms of water temperature and prey, in order to prevent the mass-mortality of cultured oysters at Gamak Bay in Yeosu City in 2007. The real-time water temperature was recorded as high, 28 to 31C, during late August. Nutrients, Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphate (DIP) were downed in September. The analyzed results of chlorophyll a content were 0.78-1.50 ${\mu}gL^{-1}$ and phytoplankton for food resources was 81 cells $mL^{-1}$, both were low. The finding here indicate that Gamak Bay is in an oligotrophic state. The mass-mortality of cultured oysters occurred 43.6% in Gamak Bay. The mortality rate of oyster were above 67.0%, at Wanpo, however, it was showed 18.3% at Gumchun. Therefore, we believe the mass-mortality of cultured oysters at Gamak Bay comes from the destruction of bio-rhythms due to high water temperature and quantitatively and qualitatively decreasing food resources due to the limitation of nutrients.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.226-235
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• 2019

Soluble silica profiles of the East Sea were described by comparing the 1970 Japanese data with the 1999-2000 ONR-JES data set, which is the most extensive collection of data currently available. Considering the ventilation mode change happened/ongoing and the features of the soluble silica to phosphate ratio we suggest a hypothesis that a utilization of soluble silica by the primary production might be exacerbated in the future. According to the silica limitation hypothesis composition of primary producers will be altered and followed by a weaker contribution of ballast against aggregates in the export production. Since the silicate cycle is deeply intertwined with the carbon cycle whether the warmed future ocean would behave like the East Sea appears to a potentially promising study theme.