• Korean Chemical Engineering Research
• /
• v.47 no.2
• /
• pp.220-229
• /
• 2009

Strain improvement and morphology investigation in bioreactor cultures were undertaken in suspended cultures of Phellinus linteus mycelia for mass production of protein-bound polysaccharides(soluble ${\beta}$-D-glucan), a powerful immuno-stimulating agent. Phellineus sp. screened for this research was identified as Phellinus linteues through ITS rDNA sequencing method and blast search, demonstrating 99.7% similarity to other Phellinus linteus strains. Intensive strain improvement program was carried out by obtaining large amounts of protoplasts for the isolation of single cell colonies. Rapid and large screening of high-yielding producers was possible because large numbers of protoplasts ($1{\times}10^5{\sim}10^6\;protoplasts/ml$) formed using the banding filtration method with the cell wall-disrupting enzymes could be regenerated in relatively high regeneration frequency($10^{-2}{\sim}10^{-3}$) in the newly developed regeneration medium. It was demonstrated that the strains showing high performances in the protoplast regeneration and solid growth medium were able to produce 5.8~6.4%(w/w) of ${\beta}$-D-glucan and 13~15 g/L of biomass in stable manners in suspended shake-flask cultures of P. linteus mycelia. In addition, cell mass increase was observed to be the most important in order to enhance ${\beta}$-D-glucan productivity during the course of strain improvement program, since the amount of ${\beta}$-D-glucan extracted from the cell wall of P. linteus mycelia was almost constant on the unit biomass basis. Therefore we fully investigated the fungal cell morphology, generally known as one of the key factors affecting cell growth extent in the bioreactor cultures of mycelial fungal cells. It was found that, in order to obtain as high cell mass as possible in the final production bioreactor cultures, the producing cells should be proliferated in condensed filamentous forms in the growth cultures, and optimum amounts of these filamentous cells should be transferred as active inoculums to the production bioreactor. In this case, ideal morphologies consisting of compacted pellets less than 0.5mm in diameter were successfully induced in the production cultures, resulting in shorter period of lag phase, 1.5 fold higher specific cell growth rate and 3.3 fold increase in the final biomass production as compared to the parallel bioreactor cultures of different morphological forms. It was concluded that not only the high-yielding but also the good morphological characteristics led to the significantly higher biomass production and ${\beta}$-D-glucan productivity in the final production cultures.

• Journal of Aquaculture
• /
• v.11 no.1
• /
• pp.11-17
• /
• 1998

Variations of hepatocyte in the larval liver of grouper, Epinephelus akaara wre examined to understand the effect of starvation during the first feeding period, 3 to 5 days after hatching. Total length of the fed larvae increased from the 5th day after hatching, although no significant difference between the fed and starved larvae was found untill the 4th day after hatching. Survival rate of the starved larvae decreased from the 4th day after hatching, and almost all of the larvae died by the 5th day after hatching. Nuclear size of hepatocyte in the starved larvae starterd to decrease from the 4th day after hatching. The sizes by 4th and 5th days after hatching in the starved larvae were 1.4 to 1.9 times smaller than those in the fed ones. Hepatocytes in the starved larvae showed irregular morphology in which the nuclei were irregularly shrunk and highly compacted from the 4th day, while hepatocyte nuclei in the fed ones maintained their uniform features during the whole experimental period. These results implied that the initial larval food should be supplied at least within the 4th day after hatching. Also, it suggested that the size of hepatocyte nucleus might be and indicator of starvation for wild and cultured grouper larvae.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.15 no.3
• /
• pp.241-250
• /
• 1982

The structure of gonads, gametogenesis and reproductive cycle of the cockle, Fulvia mutice, were studied mainly by histological observation. The materials were monthly sampled in the southern area of Yeosu from October 1980 to September 1981. F. mutica was monoecious. The gonads were situated between the liver tissues and the outer fibronuscular layers compacted by the connective tissue fibers and muscle fibers beneath the outermost layer of simple cuboidal epithelium. The gonad was composed of a number of the ovarian sacs and the testicular tubules which form the tubular structure. Testicular tubules in the mature stage sometimes contained 'testis-ova' The undifferentiated mesenchymal tissues and the eosinophilic cells were abundantly distributed on the germinal epithelium in the early development stage. With the further development of the ovary and testis, these tissues and cells gradually disapprared. The undifferentiated mesenchymal tissues and the eosinophilic cells are related to the growing of the oocytes and spermatocytes . Early multiplicating oogonium was about $10{\mu}m$ in diameter. As the oocytes grow to $27-34\times50-58{\mu}m$ by increasing cytoplasm, the oocytes connected to the basement membrane by their egg-stalks. The ripe eggs were about $60{\mu}m$ in diameter and they were surrounded by gelatinous membrane. Most male germ cells in mature stage were transformed into the spermatozoa and they formed the sperm bundles. After spawning, undischarged ripe eggs and spermatozoa remained in the ovarian sac and the testicular tubule respectively for some time, then they finally degenerated. Especially the early spent ovarian sacs in May did not contract significantly and then they took part in the secondary maturation within two or three months during the summer season. The monthly changes of the fatness well agreed with the reproductive cycle. The reproductive cycle of F. mutica could be classified into six successive stages : multiplicative, growing, mature, spent, degenerative and recovery stage. It seems that the spawning season is closely rotated to the water temperature, and the spawning occurs from May to October at about $20^{\circ}C$ in water temperature. The peak spawning seasons appeared twice a year between June and July and in September. Acknowledgement The authors wish to express their gratitude to Dr. Kim, In Bae, Dr. Chun, Seh Kyu and Dr. Yoo, Sung Kyoo of National Fisheries University of Busan and Mr. Min, Byoung Seo of National fisheries Research and Development Agency for their critical reading of the manu script.

• Journal of Korean Society of Forest Science
• /
• v.81 no.1
• /
• pp.53-65
• /
• 1992

For elucidating effective methods of restoration of forest recreational sites where management goals are maintaining naturalness and conserving natural ecosystem, seeding, fertilization and soil surface treatment were used for four years at the devastated forest-floor. For restoration of forest-floor vegetation, factorial experiment was used with a split plot design(main plot : fertilization, subplot : soil surface${\times}$seeding) and a randomized complete block design (fertilization${\times}$seeding) at the Kwanaksan Aboretum, Anyang, Kyonggido. Results were summarized as follows : Soil surface softening with tipping and ripping and straw-mat mulching (70% coverage) treatment was effective on germination, survival and growth of seeded vegetation at devastated forest-floor. Especially, straw-mat mulching treatment was effective on soil surface stabilization and seedling's survival at eroded soil surface, while complete soil surface softening treatment was effective on germination, survival and early growth of tree species of late-successional series. Introducing seeds of native species of pioneer or early-successional series, with good growth capability in barren soil was effective on rapid restoration in devastated forest-floor with its soil surface previously compacted and its surviving seeds washed away. When the seeding and straw-mat mulching after partial soil surface softening with tipping and ripping treatment were employed, it took about three years to restore the devastated forest-floor where surface erosion had been undertaken for an extended period of time and where naturally surviving seeds of native species had been washed away. Softening treatment of soil surface was effective for about two years, and seeding and soil surface treatment increased number of seedlings and improved soil surface environment through fixing of movement of the fallen leaves. Fertilizing effect was not oberserved, mainly due to seeding exposure and poor physical condition including soil surface erosion, low soil water potential and drought, etc, at the field experimental site. However, application of nitrogen and phosphate fertilizers was effective on seedling survival of the species in late-successional series, while lime application adversely affected the seedling survival.

• The Korean Journal of Quaternary Research
• /
• v.7 no.1
• /
• pp.27-39
• /
• 1993

The shingle beach as a typical pocket beach located in Jeongdo-ri, Wando, Cheolanam-do, Korea has been investigated in terms of textural characteristics, mainly gravel shape and roundness. In the Jeongdo-ri gravel beach, changes of beach profile after storm weather and textural parameters of gravels were observed and measured from May 1992 to March 1993. Beach profile is divided into two different Fair-weather zone and Storm-weather zone influenced by dynamic condition of wave energy. The former is affected by wave and tide under fair-weather condition, the latter seems to be formed under storm-weather condition. Each zone comprises a series of beach faces and berms formed by continuous sedimentary processes of swash, overwash and backwash. Storm-weather zone is subdivided into three groups having a pair of beach face and berm respectively. Mean sizes of berm gravel(45.5 mm -123.6 mm) are coarser than gravels of beach face (36.8 mm - 78.3 mm) in fair-weather zone. On the other hand, in storm-weather zone, gravels of berms (33.1 mm -82.5 mm) are finer than those of beachfaces (46.2 mm - 105.2 mm). The proportion of disc shaped gravels of berm (50.0% - 58.5 %) is higher than that of beachface (45.9 % - 51.3 %) in each subzone except C-group of storm-weather zone. And the proportion of the equant shaped gravel increases about up to 10% seaward. Therefore, shore-normal distribution of gravels seems to be affected by shape and size sorting effects. Shore-parallel distribution pattern of gravel shape is more distinctive than size distribution patterns. That is, disc and blade shaped particles decrease up to 20% and 13% respectively, and equants increase up to 34% to the westward. Gravels plotted on Sneed and Folk's triangular diagram are more compacted and elongated with decreasing size. Therefore primary gravels are shaped by characteristics of country rock e.g. cleavage, joint etc., and secondary are affected by sorting and size-controlled process evolution by wave action.

• Journal of Chest Surgery
• /
• v.30 no.12
• /
• pp.1159-1166
• /
• 1997

For Improvement of lung preservation, many tripes of preservation solution were developed and tested. The aim of this study was to compare the effect of the most frequently used extracellular type pieservation solution (Low Potassium Dextran, LPD) with a newly developed trehalose containing extracellular type preservation solution(ET-Kyoto, ETK) on postischemic lung function. Twelve New-Zealand white rabbit lungs were harvested and studied on an isolated, blood-perfused model of lung function after 4 hours of cold ischemia at $10^{\circ}C$ In group I (n=6), lungs were preserved with 100 mL/kg of LPD solution; in group II(n=6), lungs were preserved with 100 mL/kg of ETK solution. A few minutes before flushing with preservation solutions, 20$\mu\textrm{g}$ of PGEI were injected into main pulmonary artery. Functions of the preserved lung were compared with PO2, PA pressure, t acheal air pressure, and drylwet ratio. The pulmonary efferent blood oxygen tension at the end of the 60-minute reperfusion period was higher in group II compacted with group I(486.5 $\pm$ 80.3 mmHg versus $432.5\pm82.9$ mmHg at FiO2 1.0, p-value = NS). The mean pulmonary arterial pressure was similar in both $groups.(33.7\pm2.2$ mmHg versus $35.5\pm2.0$ mmHg, p-value : NS). The peak inspiratory airway pressure was significantly lower in group 11(8.010.6 mmHg versus 11.8 $\pm$ 1.4 mmHg, p-value=0.02) The water content of the lung was lower in group II $(70.2\pm6.9%$ versus 78.5 $\pm6.1%),$ but not significant. These data demonstrate that a newly-developed trehalose-containing ET-Kyoto solution yield equal or slightly superior lung function after reperfusion compared with LPD solution.

• Restorative Dentistry and Endodontics
• /
• v.30 no.2
• /
• pp.79-85
• /
• 2005

The purpose of this study was to evaluate the obturation efficiency of a non-standardized gutta-percha cone in curved root canals prepared with 0.06 taper nickel-titanium instruments. Sixty simulated curved root canals in clear resin blocks were prepared with crown-down technique using 0.06 taper rotary $ProTaper^{TM}$and ProFile (Dentsply-Maillefer) until apical canal was size 30. Root canals were randomly divided into 4 groups of 15 blocks and obturated with cold-laterally compacted gutta-percha technique by using either a non-standardized size medium gutta-percha cone or an ISO-standardized size 30 one as a master cone. Gutta-percha area ratio were calculated at apical levels of 1, 3 and 5 mm using AutoCAD 2000 after cross-sectioning, and the data were analyzed with one-way and two-way ANOVAs and Duncan's multiple range test. Non-standardized size medium cone groups showed significantly higher gutta-percha area ratio than standardized cone groups at all apical levels (p < 0.01). Non-standardized cone groups used significantly less accessory cones than standardized cone groups (p < 0.01).

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.3
• /
• pp.23-32
• /
• 2010

The purpose of this study is to quantify human energy budgets for different structures of outdoor spatial surfaces affecting thermal comfort, to analyze the impacts of tree shading on building energy savings, and to suggest desirable strategies of urban greenspace planning concerned. Concrete paving and grass spaces without tree shading and compacted-sand spaces with tree shading were selected to reflect archetypal compositional types for outdoor spatial materials. The study then estimated human energy budgets in static activity for the 3 space types. Major determinants of energy budgets were the presence of shading and also the albedo and temperature of base surfaces. The energy budgets for concrete paving and grass spaces without tree shading were $284\;W/m^2$ and $226\;W/m^2$, respectively, and these space types were considerably poor in thermal comfort. Therefore, it is desirable to construct outdoor resting spaces with evapotranspirational shade trees and natural materials for the base plane. Building energy savings from tree shading for the case of Daegu in the southern region were quantified using computer modeling programs and compared with a previous study for Chuncheon in the middle region. Shade trees planted to the west of a building were most effective for annual savings of heating and cooling energy. Plantings of shade trees in the south should be avoided, because they increased heating energy use with cooling energy savings low in both climate regions. A large shade tree in the west and east saved cooling energy by 1~2% across building types and regions. Based on previous studies and these results, some strategies including indicators for urban greenspace planning were suggested to improve thermal comfort of outdoor spaces and to save energy use in indoor spaces. These included thermal comfort in construction materials for outdoor spaces, building energy savings through shading, evapotranspiration and windspeed mitigation by greenspaces, and greenspace areas and volume for air-temperature reductions. In addition, this study explored the application of the strategies to greenspace-related regulations to ensure their effectiveness.

• Economic and Environmental Geology
• /
• v.56 no.2
• /
• pp.167-183
• /
• 2023

Gases originated from the final SNF (spent nuclear fuel) disposal site are very mobile in the barrier and they may also affect the migration of radioactive nuclides generated from the SNF. Mechanisms of gas-nuclide migration in the multi-barrier and their influences on the safety of the disposal site should be understood before the construction of the final SNF disposal site. However, researches related to gas-nuclide coupled movement in the multi-barrier medium have been very little both at home and abroad. In this study, properties of gas generation and migration in the SNF disposal environment were reviewed through previous researches and their main mechanisms were summarized on the hydrogeological evolution stage of the SNF disposal site. Gas generation in the SNF disposal site was categorized into five origins such as the continuous nuclear fission of the SNS, the Cu-canister corrosion, the oxidation-reduction reaction, the microbial activity, and the inflow from the natural barriers. Migration scenarios of gas in porous medium of the multi-barrier in the SNF repository site were investigated through reviews for previous studies and several gas migration types including ① the free gas phase flow including visco-capillary two-phase flow, ② the advection and diffusion of dissolved gas in pore water, ③ dilatant two-phase flow, and ④ tensile fracture flow, were presented. Reviewed results in this study can support information to design the further research for the gas-nuclide migration in the repository site and to evaluate the safety of the Korean SNF disposal site in view points of gas migration in the multi-barrier.