• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.30-38
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• 2008

Petroleum-based resin adhesives have extensively been used for the production of wood panels. However, with the increase of manufacturing cost and the environmental issue, such as the emission of volatile organic compounds, of the adhesive resins, it is necessary to be developed new adhesive systems. In this study, the potential of okara, which is a residue wasted from the production of tofu, for the development of bio-based adhesives was investigated. At first, the physical and chemical properties of okara were examined. After okara was hydrolyzed in acidic and/or alkaline solutions, okara-based adhesive resins were formulated with the mixtures of the okara hydrolyzates and phenol formaldehyde (PF) prepolymer. The adhesive resins were used for the fabrication of plywood panels, and then the adhesive strength and formaldehyde emission of the plywood panels were measured to examine the applicability of the resin adhesives for the production of plywood panels. The solids content and pH of the okara used in this study were around 20% and weak acidic state, respectively. In the analysis of its chemical composition, the content of carbohydrate was the highest, and followed by protein. The shear strengths of plywood fabricated with okara-based resin adhesives exceeded a minimum requirement of KS standard for ordinary plywood, but its wood failure did not reach the minimum requirement. In addition, the formaldehyde emissions of all plywood panels were higher than that of E1 specified in the KS standard. Based on these results, okara has the potential to be used as a raw material of environmentally friendly adhesive resin systems for the production of wood panels, but further researches - biological hydrolysis of okara and various formulations of PF prepolymer - are required to improve the adhesive strength and formaldehyde emission of okara-based resin adhesives.

• Journal of Chest Surgery
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• v.39 no.4 s.261
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• pp.261-268
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• 2006

Background: Current vascular prostheses are still inadequate for reconstruction of small-diameter vessels. Autologous pericardium can be a good alternative for this purpose as it already possesses good blood compatibility and shows a mechanical behavior similar to that of natural arteries. However, the clinical use of autologous pericardial tissue as a small-diameter vascular graft has limitations due to mixed outcomes from uncertain biological behavior and difficulty to gain reliable patency results in animal experiments. To study this issue, we implanted fresh and glutaraldehyde-treated autologous pericardium as small-diameter arterial grafts in dogs, and compared their time-related changes histologically. Material and Method: As a form of 5mm-diameter arterial graft, one pair of autologous pericardial tissue was used for comparison between the glutaraldehyde-treated and the glutaraldehyde-untreated grafts in the bilateral carotid arteries in the same dog. The patency of the grafts were evaluated at regular intervals with Doppler ultrasonography. After the predetermined periods of 3 days, 2 weeks, 1 month, 3 months and 6 months, the grafts in each animal were explanted. The retrieved grafts were processed for light and electron microscopic analyses following gross observation. Result: Of 7 animals, 2 were excluded from the study because one died postoperatively due to bleeding and the other was documented as one side of the grafts being obstructed. All 10 grafts in the remaining 5 dogs were patent. Grossly, a variable degree of thromboses were observed in the luminal surfaces of the grafts at 3 days and 2 weeks, despite good patency. Pseudointimal smooth blood-contacting surfaces were developed in the grafts at f month and later. By light microscopy, mesothelial cell layers of the pericardial tissue were absent in all explanted grafts. Newly formed endothelial cell layers on the blood-contacting surface were observed in both the glutaraldehyde-treated and fresh grafts at 3 months and later. The collagen fibers became degraded by fragmentation in the fresh graft at 1 month and In the glutaraldehyde-treated graft at 3 months. At 6 months, the collagen layers were no longer visible in either the glutaraldehyde-treated or fresh grafts. By electron microscopy, a greater amount of coarse fibrin fibers were observed in the fresh grafts than in the glutaraldehyde-treated grafts and, more compact and well-arrayed layers were observed in the glutaraldehyde-treated grafts than in the fresh grafts. Conclusion: The glutaraldehyde-treated small-diameter pericardial arterial grafts showed a better endothelialization of the blood-contacting surface and a slower fragmentation of the collagen layers than the fresh grafts, although it has yet to be proven whether these differences are so significant as to affect the patency results between the groups.

• Journal of Wetlands Research
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• v.8 no.4
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• pp.41-47
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• 2006

Global climatic changes are expected to influence various biogeochemical processes in wetland ecosystems. In particular, coastal mud flat is anticipated to be affected directly by temperature increase as well as indirectly by a sea level rise and changes in precipitation. This study aimed to determine changes in methane production under different temperature and salinity by employing a laboratory-scale manipulation experiment. Soil samples were collected from a mud flat in Dong-Gum Kang-Hwa island in winter and two types of experiments were conducted. In the first experiment soil samples at 0-5 cm, 5-10 cm depth were incubated under same salinity with pore water and diluted salinity to 50 % of natural condition for 20 days and methane production was measured every other days. In the second experiment, soil samples at 5-10 cm depth were incubated in different temperature, $5^{\circ}C$ and $15^{\circ}C$, under same salinity conditions with first experiment for 31 days and methane production was measured. Results of the first experiment revealed that higher amount of methane was produced at 5-10 cm depth, and salinity effect was predominant at the end of the experiment. The second experiment showed that methane production was higher in $15^{\circ}C$ than $5^{\circ}C$. In addition, methane production was higher when sea water diluted to 50 % compared to control. Global climatic changes are expected to influence various biogeochemical processes in wetland ecosystems. In particular, coastal mud flat is anticipated to be affected directly by temperature increase as well as indirectly by a sea level rise and changes in precipitation. This study aimed to determine changes in methane production under different temperature and salinity by employing a laboratory-scale manipulation experiment. Soil samples were collected from a mud flat in Dong-Gum Kang-Hwa island in winter and two types of experiments were conducted. In the first experiment soil samples at 0-5 cm, 5-10 cm depth were incubated under same salinity with pore water and diluted salinity to 50 % of natural condition for 20 days and methane production was measured every other days. In the second experiment, soil samples at 5-10 cm depth were incubated in different temperature, $5^{\circ}C$ and $15^{\circ}C$, under same salinity conditions with first experiment for 31 days and methane production was measured. Results of the first experiment revealed that higher amount of methane was produced at 5-10 cm depth, and salinity effect was predominant at the end of the experiment. The second experiment showed that methane production was higher in $15^{\circ}C$ than $5^{\circ}C$. In addition, methane production was higher when sea water diluted to 50 % compared to control. These results suggest that methane production is highly influenced by changes in temperature and salinity in coastal mud flat. And that global climatic change may induce biological feedback by affecting production of another greenhouse gas, namely methane from coastal mud flat.

• Journal of Veterinary Clinics
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• v.28 no.5
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• pp.486-496
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• 2011

A special mesenchymal tissue layer called perichondrium has a chondrogenic capacity and is a candidate tissue for engineering of cartilage. To overcome limited potential for chondrocyte proliferation and re-absorption, we studied a method of cartilage tissue engineering comprising chondrocyte-hydrogel pluronic complex (CPC) and cultured perichondrial cell sheet (cPCs) which entirely cover CPC. For effective cartilage regeneration, cell-sheet engineering technique of high-density culture was used for fabrication of cPCs. Hydrogel pluronic as a biomimetic cell carrier used for stable and maintains the chondrocytes. The human cPCs was cultured as a single layer and entirely covered CPC. The tissue engineered constructs were implanted into the dorsal subcutaneous tissue pocket on nude mice (n = 6). CPC without cPCs were used as a controls (N = 6). Engineered cartilage specimens were harvested at 12 weeks after implantation and evaluated with gross morphology and histological examination. Biological analysis was also performed for glycosaminoglycan (GAG) and type II collagen. Indeed, we performed additional in vivo studies of cartilage regeneration using canine large fullthickness chondrial defect model. The dogs were allocated to the experimental groups as treated chondrocyte sheets with perichondrial cell sheet group (n = 4), and chondrocyte sheets only group (n = 4). The histological and biochemical studies performed 12 weeks later as same manners as nude mouse but additional immunofluorescence study. Grossly, the size of cartilage specimen of cPCs covered group was larger than that of the control. On histological examination, the specimen of cPCs covered group showed typical characteristics of cartilage tissue. The contents of GAG and type II collagen were higher in cPCs covered group than that of the control. These studies demonstrated the potential of such CPC/cPCs constructs to support chondrogenesis in vivo. In conclusion, the method of cartilage tissue engineering using cPCs supposed to be an effective method with higher cartilage tissue gain. We suggest a new method of cartilage tissue engineering using cultured perichondrial cell sheet as a promising strategy for cartilage tissue reconstruction.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.467-473
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• 2007

Although the dominant land use at the Imha-dam watershed is forest areas, soil erosion has been increasing because of intensive agricultural activities performed at the fields located along the stream for easy-access to water supply and relatively favorable topography. In addition, steep topography at the Imha-dam watershed is also contributing increased soil erosion and sediment loads. At the Imha-dam watershed, outflow has increased sharply by the typhoons Rusa and Maemi in 2002, 2003 respectively. In this study, the Soil and Water Assessment Tool (SWAT) model was evaluated for simulation of flow and sediment behaviors with long-term temporal and spatial conditions. The precipitation data from eight precipitation observatories, located at Ilwol, Subi and etc., were used. There was no significant difference in monthly rainfall for 8 locations. However, there was slight differences in rainfall amounts and patterns in 2003 and 2004. The topographical map at 1:5000 scale from the National Geographic Information Institute was used to define watershed boundaries, the detailed soil map at 1:25,000 scale from the National Institute of Highland Agriculture and the land cover data from the Korea Institute of Water and Environment were used to simulate the hydrologic response and soil erosion and sediment behaviors. To evaluate hydrologic component of the SWAT model, calibration was performed for the period from Jan. 2002 to Dec. 2003, and validation for Jan. 2004 to Apr. 2005. The $R^2$ value and El value were 0.93 and 0.90 respectively for calibration period, and the $R^2$ value and El value for validation were 0.73 and 0.68 respectively. The $R^2$ value and El value of sediment yield data with the calibrated parameters was 0.89 and 0.84 respectively. The comparisons with the measured data showed that the SWAT model is applicable to simulate hydrology and sediment behaviors at Imha dam watershed. With proper representation of the Best Management Practices (BM Ps) in the SWAT model, the SWAT can be used for pre-evaluation of the cost-effective and sustainable soil erosion BMPs to solve sediment issues at the Imha-dam watershed. In Korea, the Universal Soil Loss Equation (USLE) has been used to estimate the soil loss for over 30 years. However, there are limitations in the field scale mdel, USLE when applied for watershed. Also, the soil loss changes temporarily and spatially, for example, the Imha-dam watershed. Thus, the SW AT model, capable of simulating hydrologic and soil erosion/sediment behaviors temporarily and spatially at watershed scale, should be used to solve the muddy water issues at the Imha-dam watershed to establish more effective muddy water reduction countermeasure.

• Korean Journal of Microbiology
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• v.42 no.2
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• pp.111-115
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• 2006

A feeding trial was conducted to test the use of marine yeasts isolated from seawaters and sediments as a dietary source in cultivating a Cladocera, Moina macrocopa which is available as an alternative live food for fish larvae. The marine yeast-fed M. macrocopa had similar essential amino acid profiles to the documented values for Rotifers and Artemia enriched in microalgae and commercial diets. Erythrobacter sp. $S{\pi}-1$ lacked ${\omega}-3$ high unsaturated fatty acids (HUFAs), $20:5{\omega}-3$ (EPA) and $22:6{\omega}-3$ (DHA), which were also poor but detected in both the marine yeasts. An increase in the $20:5{\omega}-3$ and $22:6{\omega}-3$ levels, compared with the levels in marine yeast strains themselves, was more pronounced in the $22:6{\omega}-3$ level of Moina fed the Candida sp. Y-16, resulting in a high DHA:EPA ratio. When the Moina diets were switched, their ${\delta}^{13}C$ values shifted gradually toward the values of the switched diets. Diet switch from Erythrobacter sp. $S{\pi}-1$to Candide sp. Y.16 resulted in a more rapid turnover of Moina tissue carbon than that in the inverse case. When fed a mixed diet, the ${\delta}^{13}C$ values of Moina tissue approached the value of marine yeasts immediately. These temporal changes in the ${\delta}^{13}C$ values of Moina tissue indicate the preferential ingestion of marine yeasts and a selective assimilation of the carbon originated from marine yeasts. These findings suggest that marine yeasts, particularly Candida sp. Y-16, are highly available to mass cultures of M. macrocopa, providing better nutritional and dietaty values than the commercial diet (Erythrobacter sp. $S{\pi}-1$).

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.232-242
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• 2002

To investigate the effects of arbuscular mycorrhizal (AM) fungus (Glomus intraradices) colonization on drought-stress tolerance, leaf water potential, chlorophyll concentration, P content and carbohydrate composition were examined in perennial ryegrass (Lolium perenne L.) plants exposed to drought-stressed or well-watered conditions. Drought stress significantly decreased leaf water potential, P content and leaf growth. These drought-induced damages were moderated by mycorrhizal colonization. Drought stress decreased the concentration of soluble sugars in shoots. AM plants had a higher foliar soluble sugar than non-AM plants under drought stress condition. Drought stress depressed the accumulation of starch and fructan in shoots, but stimulated in roots. Under drought-stressed condition, starch concentration in roots was higher in non-AM plants than in AM plants. Fructan was the largest pool of carbohydrates, showing the highest initial concentration and the highest net increase for 28 days of treatment. Drought stress slightly decreased fructan concentration in shoots, but remarkably increased in roots. Under drought-stressed condition, fructan concentrations in non-AM and AM shoots at day 28 were 18.7% and 13.3% lower than the corresponding values measured at well-watered plants. However, in the roots, fructan accumulation caused by drought was lessen 13.6% by mycorrhizal colonization. The results obtained suggest that mycorrhizal colonization improves drought tolerance of the host plants by maintaining higher leaf water status and P status, and by retaining more foliar soluble sugars.

• Journal of the Korean Society of Radiology
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• v.4 no.1
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• pp.31-35
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• 2010

Recently, the incidents of direct or indirect radiation exposure due to increase of use of radiation or radioisotope are on the increase in medical and industrial circles. If cells are irradiated, free radicals are created through biological process, and cells are directly or indirectly damaged. This research intends to explore into the effect of saponin at the level of cell (in vitro) and entity (in vivo), using red ginseng extract "saponin", as radioprotective agent. In the experiment implemented at the level of cell (in vitro), degree of cell activity was measures by adding mouse mesenchymal stem cells "C3H/10T1/2 cells" into red ginseng extract "saponin(0, 0.05, 0.2, and 0.4 g/L)", and then the optimal concentration of saponin influencing cells was calculated, in 24, 48, 72, and 96 hours after gamma irradiation at the optimal concentration of saponin, each cell survival rate was observed through XTT assay. The best time period of cultivation for the optimal activity of C3H/10T1/2 cells was as 48 hours, and the degree of optimal activity was shown at 0.05 g/L. In 48 hours after irradiation of 5 Gy to C3H/10T1/2 cells at 0.05 g/L, the degree of activity of cells increased by 10%. In the experiment implemented at the level of entity (in vivo), red ginseng extract "saponin" at a dose of 100 mg/kg/day was injected into the abdominal cavity of six-week immature mouse for two weeks. Right after the last abdominal injection, total body irradiation of gamma rays was carried out at a dose of 5 Gy and 10 Gy. And after irradiation, the blood sample was taken, and then the number of red corpuscles was counted. In result, the decrement of experimental group treated with red ginseng extract "saponin" was 2.3 times larger than that of control group. In view of the results so far achieved, it was revealed that red ginseng extract "saponin" has a radiation exposure protection effect in the experiment implemented at the level of cell (in vitro). In case of animal experiment, the decrement of number of red corpuscles decreased. Finally, it is necessary to carry out more various researches continuously.

• Journal of Plant Biotechnology
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• v.41 no.4
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• pp.180-193
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• 2014

In plants, a shoot apex has a small region known as the shoot apical meristem (SAM) having a group of dividing (initiating) cells. The SAM gives rise to all the groundabove structures of plants throughout their lifetime, and thus it plays important role in growth and development of plants. This review describes theories to explain the SAM organization and function developed over the last 250 years. Since in 1759 German botanist C. F. Wolff has described firstly the SAM, in 1858 Swiss botanist C. N${\ddot{a}}$geli proposed the apical cell theory from the observation of a large single apical cell in the SAM of seedless vascular plants: however, this view was recognized to be unsuitable to seed plants. In 1868, German botanist J. Hanstein suggested the histogen theory: this concept subdividing the SAM into dermatogen, periblem, and plerome was unable to generally apply to seed plants. In 1924, German botanist A. Schmidt proposed the tunica-corpus theory from the examination of angiosperm SAM in which two parts show different planes of cell division: this theory was proved to be not suitable to gymnosperm SAM, not have stable surface tunica layer. In 1938, American botanist A. Foster described zones in gymnosperm SAM based on the cytohistologic differentiation and thus called it a cytohistological zonation theory. With works by E. Gifford, in 1954, this zonation pattern was demonstrated to be also applicable to angiosperm SAM. As another theory, in 1952 French botanist R. Buvat proposed the m${\acute{e}}$rist${\grave{e}}$me d'attente (waiting meristem) theory: however, this concept was confuted because of its negation of function during vegetative growth phase to central initial cells. Rescent studies with Arabidopsis thaliana have found that formation and maintenance of the SAM are under the control of selected genes: SHOOTMERISTEMLESS (STM) gene forms the SAM, and WUSCHEL (WUS) and CLAVATA (CLV) genes function in maintaining the SAM; signaling between WUS and CLV genes act through a negative feedback loop.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.91-97
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• 2006

For efficient removal of nitrogenous compounds produced in recirculating aquaculture system, the N removal characteristics of immobilized mixed microorganisms were investigated at various mixing ratios of photosynthetic bacteria (PSB) immobilized in PVA beads or CTA cubes and ammonium utilizing bacteria (AUB) immobilized in PVA beads. On the optimal medium of AUB, the maxium gas production rate was obtained at the mixing ratio of 10:40 (PSB:AUB), and the gas production rate increased as the portion of AUB beads in the mixed beads increased. When the mixing ratios of PSB:AUB beads were 50:0, 40:10, 25:25 and 10:40, the final pHs were measured to be 6.29, 6.01, 5.69 and 5.13, respectively. On the optimal medium of PSB, however, the volume and the rate of gas production decreased remarkably as the portion of AUB beads in the mixed beads increased. The final pH was measured to be approximately 6.5, regardless of the mixing ratio. In the reactions by the mixed culture of PSB cubes and AUB beads, all results showed the same tendency of those by the mixed culture of PSB and AUB beads, but the volume and the rate of gas production decreased remarkably, even with 0.2ml of gas production in control. From all the results, the use of mixed PSB and AUB beads at the ratio of 10:40 seems to be efficient to remove nitrogenous compounds in wastewater from recirculating aquaculture system.