• The Korean Journal of Malacology
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• v.30 no.3
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• pp.219-226
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• 2014

The effects of different stocking densities on the growth and survival rate of the abalone, Haliotis discus hannai, were investigated in marine net cage for two years. Stocking density was set 15, 30, 45 and 60 percentage $(=per.)/m^2$ with share to cross-sectional area per shelter. The primary rearing period (PRP) and the secondary rearing period (SRP) were conducted by a year. One year mean water temperature of PRP and SRS showed the difference about $2^{\circ}C$. In the growth (initial mean shell length of abalone : $36.14{\pm}2.28mm$) of PRP, the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) of the $15per./m^2$ were higher than those of density groups (P < 0.05). Survival rates of all density groups were showed no significant difference. In the growth (mean shell length of abalone : $55.26{\pm}6.93mm$) of SRP, ARG, DGR and SGR of stocking density groups showed no significant difference except for $45per./m^2$ density group. Survival rate in the low-density (15, $30per./m^2$) was more than 70%, and those of the high-density (45, $60per./m^2$) were less than 31% and 9%, respectively. These results showed that the appropriate stocking density for $15per./m^2$ was seven hundred fifty number per one net cage ($2.4{\times}2.4m$), during PRP using 3-4 cm abalone in length. Also for the secondary rearing period, the optimal stocking density (shell length 5-6 cm of abalone) consider with the economical efficiency was determined to be $30per./m^2$, resulting the productivity improved.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.412-420
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• 1995

Oxygen consumption (OC), ammonia nitrogen (AN ) excretion and body composition were measured to study the effects of energy/protein ratio (EPR) on the utilization of protein and energy in juvenile rockfish, Sebastes schiegeli. Juvenile rockfish were divided into three groups that they fed three isocaloric diets (3,5kcal/g) containing 30 (I), 40 (II) or $50\%$ crude protein (III). EPR of the three experimental diets were 11.5 (I), 8.7 (II) and 7.0kcal/g III), respectively. Juvenile rockfish (wet wt. 2.9-3.1g) were cultured in 501 aquaria with the constant environmental condition of $20-24^{\circ}C$ water temperature and $34\%o$ salinity. For 24 hr after feeding the diets, juvenile rockfish fed diet III had a higher OC than did the fish from groups fed diets I and II, and average OC of the fish fed diets I, II and III were $0,93\pm0.02^a,\;0.92\pm0.02^a\;and\;1.03\pm0.03^bml\;O_2/g/h$, respectively. AN responses of juvenile rockfish to increasing levels of dietary protein (decreasing dietary EPR) were significantly different among three groups in which dietary protein at elevated levels increased the excretion of AN for 24 hr after feeding the diets. Average AN excretion of the fish fed diets I, II and III were $9.14\pm0.39^a,\;12.41\pm 0.53^a\;and\;14.89\pm0.55^c\;{\mu}g\;N/g/h$ respectively. The body protein content of the fish fed diet II for 59 days was significantly higher than that of the fish fed the other diets. But, there were no significant differences between three groups in body lipid, carbohydrate and ash contents. These results indicate that EPR of 9.7kcal/g (diet II) could be a optimum EPR in juvenile rockfish diet.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.184-190
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• 1984

Sardine, Sardinops melanosticta, has been caught more than fifty thousand metric tons every year in adjacent sea of Korea, but most of them used for uneatable fish meal because of their rapid spoilage. Usually it is known that the main reason of putrefaction of foods is caused by the maicro-organisms included in them. Therefore, this experiment was carried out to identify the micro-organisms isolated from the intestine of fresh sardine and characterize their proteolytic enzymes produced from them. Aerobic cell count ranged from $1.7{\times}10^4\;to\;3.6{\times}10^5/g$, while anaerobic cell count, from $2.9{\times}10^4\;to\;5.5{\times}10^5/g$. Most of the isolated strains were psychrotrophic mesophiles. Among the two hundred and eighty strains isolated from the fresh samples, fifty-six strains ($20.0\%$) were proteolytics, one hundred and seventy-five strains ($62.5\%$) were lipolytics and tenty-nine strains ($10.5\%$) had the ability to produce hydrogn sulfide. The most predominantly isolated microbial groups from the fresh sardine were Moraxella ($31.4\%$) and Pseudomonas sup. ($28.6\%$). Flavobacterium-Cytophaga, Vibrio, Acinetobacter, Micrococcus spp. and Enterobacteriaceae appeared from $7.9\%\;to\;5\%$ out of total tested strains. The average bacterial count in the spoiled samples (stored at about $18^{\circ}C$ for 48 hours) was increased to the level of $2.9{\times}10^8/g$ for aerobes, $1.5{\times}10^8/g$ for anaerobes, then one hundred and ten strains, corresponding to $52\%$, out of two hundred and thirteen strains submitted to the test were proteolytics. The strongest proteolytic bacterium among the two hundred and eighty strains was identified as Pseudomonas 101 which grew best at $25^{\circ}C$. The optimum condition for the activity of the proteolytic enzyme produced by Pseudomonas 101 appeared $35^{\circ}C$ and pH 9.0, but the activity was relatively unchanged between 5.0 and 11.0 of pH and between $30^{\circ}C\;and\;50^{\circ}C$ of temperature.

• Journal of Sericultural and Entomological Science
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• v.15 no.2
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• pp.45-53
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• 1973

1. The sericin solubility increased rapidly as the increase of water M-alkalinity. 2. The acidity of the treated water was nutralized at the over 25ppm of M-alkalinity. 3. The more M-alkalinity of the sample water is, the more M-alkalinity was found after cocoon treat. 4. The total hardness of sample water seemed to be droped as M-alkalinity increased. 5. The sericin solubility also seemed to be droped as the increase of water acidity. 6. In case of treat finish with cocoon, the acidity and total hardness seemed to increase as the acidity of the water increased, but M-alkalinity was nutralized at 20~40 ppm of water acidity or the M-alkalinity could not be found in case over 40ppm of acidity. 7. In case increase of iron component with sample water, sericin solubility seemed to drop down, and mangan component showed the same nature but dull drop. 8. After cocoon was treated with water, acidity, M-alkalinity and total hardness were increased by the extraction from cocoon shell because of pH and treating temperature but not because of iron componnent. Mangan component, however, affected as to increase of acidity and total hardness but to decrease for M-alkalinity. 9. In case change of M-alkalinity and total hardness, sericin solubility has increased also. 10. In case constant pH and total hardness, the more M-alkalinity is, the more sericin solubility was found. 11. In case constant pH, total hardness, and M-alkalinity, the more acidity is, the less sericin solubility was found. 12. In case constant pH(6.8) and M-alkalinity, the more total hardness is, the less sericin solubility was found. 13. Though the combination of water, high solubility water, medium solubility water and low solubility water were prepared. The high solubility water desolved sericin 2.2% more than low solubility water. And the medium solubility water desolved sericin as much as 2.4~2.9%. 14. It was found that the most important factors for filature water are pH, M-alkalinity, acidity and total hardness which may need more words for optimum filature water development. 15. In case of repeat use of water, the buffer action of water has increased so that the sericin solubility to be decreased.

• Journal of the Korean Electrochemical Society
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• v.20 no.4
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• pp.67-74
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• 2017

Layered Ni-rich NCM cathode materials $Li[Ni_xCo_{(1-x)/2}Mn_{(1-x)/2}]O_2$ ($x{\geq}0.6$) have advantages of high energy density and cost competitive over $LiCoO_2$. The discharge capacity of NCM increases proportionally to the Ni contents. However, there is a problem that it is difficult to realize the stable electrochemical performance due to cation mixing. In this study, synthesis conditions for the layered Ni-rich NCMs are investigated to achieve deliver the ones having good electrochemical performances. Synthesis parameters are atmosphere, lithium source, synthesis time, synthesis temperature and Li/M (M=transition metal) ratio. The degree of cation mixing gets worse as the Ni content is increased from $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$ (NCM6) to $Li[Ni_{0.8}Co_{0.1}Mn_{0.1}]O_2$ (NCM8). It is confirmed that higher level of cation mixing affects negatively on the electrochemical performance of NCMs. Optimum synthesis conditions are explored for NCMx (x=6, 7, 8) in order to reduce the cation mixing. Under optimized conditions for three representative NCMx, a high initial discharge capacity and a good cycle life are obtained for $180mAh{\cdot}g^{-1}$, 96.2% (50 cycle) in NCM6, $187mAh{\cdot}g^{-1}$, 94.7% (50 cycle) in NCM7, and $201mAh{\cdot}g^{-1}$, 92.7% (50 cycle) in NCM8, respectively.

• Journal of Bio-Environment Control
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• v.23 no.1
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• pp.60-64
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• 2014

These studies were conducted to identify the effects of non-perforated breathable package film on storability at $1^{\circ}C$, $8^{\circ}C$, and $20^{\circ}C$ storage of 'Fuji' apples. The fresh weight loss rate was less than 2.0% in all non-perforated breathable films at three different storage periods and temperatures, $1^{\circ}C$; 210 days, $8^{\circ}C$; 75 days, and $20^{\circ}C$; 30 days except for the perforated film. 1,300 cc ($1^{\circ}C$), 5,000 cc ($8^{\circ}C$), and 10,000 cc ($20^{\circ}C$) films were closed at the optimum MA storage condition by carbon dioxide and oxygen concentration. Ethylene concentration was lowest at the 40,000 cc film in every temperatures during storage. The 1,300 cc film established higher result in soluble solid and vitamin C content than any other films at $1^{\circ}C$, also showed higher in visual quality by panel test. The 5,000 cc film had the best results on soluble solid and off-flavor in $8^{\circ}C$. In the $20^{\circ}C$ storage after 30 days of treatment the 10,000 cc film had highest firmness and visual quality. Following these results, it come to conclusion the suitable type of non-perforated breathable film such as 1,300 cc at $1^{\circ}C$, 5,000 cc at $8^{\circ}C$, and 10,000 cc at $20^{\circ}C$ for MA storage in 'Fuji' apples.

• Journal of Mushroom
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• v.13 no.3
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• pp.212-216
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• 2015

A new commercial strain "Mongdol" of oyster mushroom was developed by hyphal anastomosis. It was improved with hybridization between monokaryotic strain derived from Pleurotus ostreatus ASI 0627 and dikaryotic strain derived from P. ostreatus ASI 2929. The optimum temperature of mycelial growth and fruiting body development were $25{\sim}30^{\circ}C$ and $12{\sim}18^{\circ}C$, respectively. When two different media including PDA (potato dextrose agar medium) and MCM (mushroom complete medium) were compared, the mycelial growth of this mushroom was faster in MCM than in PDA. Similar result was observed with the control strain P. ostreatus ASI 2504. Analysis of the genetic characteristics of the new cultivar "Mongdol" showed a different DNA profile as that of the control strain ASI 2504, when RAPD (Random Amplified Polymorphic DNA) primer URP3 and URP6 were used. Fruiting body production per bottle was about 106 g using demonstration farms. The color of pileus was blackish gray and the stipe was long. Therefore, we expect that this new strain "Mongdol" will satisfy the consumer's demand for high quality mushrooms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.131-140
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• 2015

To set up unicellular cyanobacterial strains with photo-biological $H_2$ production potential, live samples were repeatedly collected from 68 stations in the coastal zone of Korea for the four years since 2005. Among 77 cyanobacterial strains established six (KNU strains, CB-MAL002, 026, 031, 054, 055 and 058) were finally chosen as the excellent strains for $H_2$ production with $H_2$ accumulation over 0.15 mL $H_2\;mL^{-1}$ under general basic $H_2$ production conditions as well as positive $H_2$ production for more than 60 hr. To explore optimum procedures for higher $H_2$ production efficiency of the six cyanobacterial strains, the inter-strain differences in the growth rate under the gradients of water temperature and salinity were investigated. The maximum daily growth rates of the six strains ranged from 1.78 to 2.08, and all of them exhibited $N_2-fixation$ ability. Based on the similarity of the 16S rRNA sequences, all the test strains were quite close to Cyanothece sp. ATCC51142 (99%). The six strains, however, were grouped into separate clades from strain ATCC51142 in the molecular phylogeny diagram. Chlorophyll- a content was 3.4~7.8% of the total dried weight, and the phycoerythrin and phycocyanin contents were half of those in the Atlantic strain, Synechococcus sp. Miami BG03511. The growth of the six strains was significantly suppressed at temperatures above the optimal range, $30{\sim}35^{\circ}C$, to be nearly stopped at $40^{\circ}C$. The growth was not inhibited by high salinities of 30 psu salinity in all the strains while strain CB055 maintained its high growth rate at low salinities down to 15 psu. The euryhaline strains like CB055 might support massive biotechnological cultivation systems using natural basal seawater in temperate latitudes. base seawater. The biological and ecophysiological characteristics of the test strains may contribute to designing the optimal procedures for photo-biological $H_2$ production by unicellular cyanobacteria.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.134-141
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• 2000

For electrochemical treatment of industrial wastewater, the effects of voltage, distance between electrodes, initial pH and NaCl concentrations on removal of pollutants were investigated in a batch electrolysis system. Temperature and pH in electrochemical reactor increased with increase in supplied voltage, but no significant change in EC was found. Removal of COD, turbidity, T-N and T-P were also enhanced with increase in the voltage. On the conditions of short distances between electrodes and long electrochemical reaction times, it was found that COD and T-N were very effectively removed in the system. Regardless of the distances, more than 80% of turbidity and T-P were removed at the beginning of reaction. When initial pH of the wastewater was about 7, the highest efficiency of COD removal was found in the system. On the other hand, removal efficiency of turbidity was unlikely affected by initial pH of the wastewater. T-N removal was increased with increase in initial pH. T-P was successfully removed in the pH range of 5 to 9 with varying removal efficiency of 79 to 96% after 2 minutes of electrochemical reaction time. Addition of NaCl into the electrochemical reactor increased removal efficiency of electrochemical treatment. The highest removal efficiency of COD and T-P, turbidity and T-N was obtained at NaCl concentrations of 500mg/L, 1,000 mg/L and 500mg/L, respectively.

• Korean Journal Plant Pathology
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• v.3 no.2
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• pp.114-119
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• 1987

Banana blast was frequently encountered in greenhouses of Jeju province during a local survey of plan diseases from 1985 to 1986. The disease incidence on banana was very severe up to $100\%$ in a greenhouse. The causal fungus was identified as Pyricularia angulata Hashioka based on mycological characteristics and Path genicity of the fungus. The symptom of blast produced on leaves of banana was circular to oval, dark brow spots with yellow margins which measured 1-10mm in diameter, and the symptom on fruits was circular to oval reddish brown or dark brown, depressed spots which measured up to 20mm in diameter. The symptoms were scattered not only on leaves and fruits of banana but. also on petioles, leaf sheaths, bunch stalks and crowns The pathogen was characterized that conidia were hyaline, 2 septated, ovate to pyriform with a small hilum solitary at ends of den tides of conidiophores, and measured $16.0-34.0\times7.0-12.0{\mu}m$ (average $22.5\times9.0{\mu}m$) and conidiophores were mostly 2 septated, occasionally 2 or 3 branched, denticulate at the tips, and measured $7.5-100.0\times3.0-5.0{\mu}m$(average $90.0\times4.0{\mu}m$). The optimum temperature range for mycelial growth of the fungus on PDA was $26-28^{\circ}C$. The result of pathogenicity tests revealed that P. angulata had pathogenicity only on banana. On the other hand Pyricularia grisea (Cke.) Sacc. isolated from Digitaria sanguinalis(L.) Scopo. was not pathogenic to banana. It was revealed that the leaves were the most susceptible to P. angulata among several parts of banana in inoculation tests. Thirty-day-old fruits of banana were more susceptible to the fungus than 60-day-old fruits, and bunch stalks were more susceptible than the fruits.