• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.244-250
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• 1996

The objectives of this paper were to study the existence of resistant substance to pine gall midge from needles of Pinus densiflora, P. thunbergii, P. virginiana, and P. thunbergii${\times}$P. virginiana, and also to investigat whether terpenoids, fragrant substance contained in those species seduce or evade imago of pine gall midge to oviposit. Also, terpenoids and phenolic compounds were bioassayed on larva. The results are follows. Adults of pine gall midge oviposited indiscriminately all investigated pine species, while gall formation rate by pine gall midge showed 0% in Pinus virginiana, 9% in P. thunbergii${\times}$P. virginiana, 22% in P. thunbergii. It is suggested that young larvae is necrotized by resistant substance in the needles of P. virginiana. This results might mean that fragrant substance, terpenoids, extracted from pine species is not seducible or evadable substance. Larvae of pine gall midge placed on terpenoid and resin were not necrotized. The necrosis rate of larvae of pine gall midge cultivated in the solution of phenolic compounds extracted from needles of P. virginiana, salicylic acid and chitinase showed 89, 92, and 86% respectively. And necrosis rate was 56 and 59% in phenolic compounds extracted from P. densiflora and gallic acid respectively. So, it is postulated that phenolic compounds contained in needles of P. virginiana, salicylic acid and chitinase are resistant substance to pine gall midge.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.225-231
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• 2006

To investigate the effect of feeding rare earth (RE) on the performance of breeder hens a feeding trial with sixteen thousands of 158 day old Ross broiler breeder hens was conducted for thirty weeks. A mixture of RE- chlorides containing mainly La, Ce, and Pr was mixed into corn-soy based diet at two levels, 300 and 600 mg/kg, All the hens were housed in flat layer houses and the ratio of male to female was maintained at one to ten. Dietary supplementation of the of RE at a level of 300 mg/kg made the hens reach egg production peak higher by about 6% and earlier by about two weeks. As a result, it made higher hatchable egg production by 3.5%. It also reduced dramatically the mortality of both male and female breeders(P<0.05). Egg weight was slightly increased but egg qualify was not much influenced by dietary supplementation of RE. Egg albumin hight and Haugh unit were significantly improved while egg shell thickness, egg breaking strength and yolk color were similar to those of the control. Experimental results appeared to show a good possibility that egg fertility and hatchability were improved by feeding RE. Dietary supplementation of RE at a level of 300 mg/kg should be acceptable but not the 600 mg/kg level for breeder hens. Further studies on the effect of RE on egg fertility and hatchability appears to be necessary.

• Journal of fish pathology
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• v.20 no.1
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• pp.41-47
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• 2007

To investigate the cause of the mass mortality during rockbream, Oplegnathus fasciatus seed production, the water quality and bacterial counts of sea water in breeding tanks was measured 20days post the hatch. During breeding of rockbream fry, the environmental factors of water quality were detected as pH, ammonia COD, phosphate at the supply of the food organisms and the seawater. pH was decreased from the 8.21 of the 1 day per hatch (dph) to 7.56 of the on the 7 dph. Ammonia was conversely increased 0.49 ppm of the 1 dph to 0.85 ppm of 10 dph. As the adding of the chlorella and the rotifer tanks, COD was increased the 3.3 times and 1.2 times than those of pre-adding respectively. The phosphate and the ammonia were also increased 1.7 and 2.3 times, with adding the chlorella respectively, which exceeded the second grade for sea water evaluation level, 0.015 ppm and 0.1 ppm respectively. Water quality was not improved by PSB (Photosynthetic Bacteria) treatment, which increased the value of COD in 1.7 times, phosphate in 2.7 times and ammonia in 1.4 times. The number of the bacteria was also increased along the dph. According to the treatment of chlorella, the number of total bacteria increased in 1.4 times and those of Vibrio sp. 1.6 times. The lethal concentration of ammonia was investigated that over than 10 ppm could killed the fry of rockbream within 28 hrs, but 40% in 2 ppm.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.339-344
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• 2010

Oxygen depleted water mass can damage aquatic animals not only in direct way but also in indirect way by generating toxic substances including occurrence of hydrogen sulfide and ammonia which are also highly detrimental to animal life in the water mass. An oxygen dissolution device was developed, which makes turnover of the oxygen rich (over 20 mg/L) surface water down to the bottom where hypoxia is evident and tested the device in terms of oxygen recovery in the oxygen depleted bottom water. the device with turnover rates of $3.6\;m^2$/min at the liquid oxygen injection rate of 48~26.3 L/min could recover dissolved oxygen level to 7~25 mg/L at depth 7 m to lead to the dissolution level of over 90% by the supply of liquid oxygen. The running advantage of the device is that it does not require any auxiliary tank and higher energy for operation. Therefore, it can be highly useful device to relieve damages to the farmed animals in the oxygen depleted waters.

• Korean Journal of Poultry Science
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• v.32 no.2
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• pp.113-123
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• 2005

Avian influenza (AI) virus (AIV) is distributed worldwide and it has been isolated from various species of wild and domestic birds. AI transfers with high speed and shows diverse pathogenicity syndroms. In Korea, several low Pathogenic AIV, H9N2, have been isolated from the commercial farms with severe decrease of egg production and mortality resulted in severe economic loss since 1996. Therefore, it has been requested to develop AI vaccines to prevent clinical signs and economic losses from the field infection of AIV. To develop a killed vaccine that efficiently prevents low pathogenic AIV (H9N2), evaluation on the pathogenicity and selection of an inactivator for H9N2 is taking place and is being tested safety and immunogenicity of vaccine produced. Based on the pathogenicity test and viral reisolation test, the ADL0401 isolate is the characteristic low pathogenic AIVs and has fairly similar biologic functions compared with MS96 which is the official low pathogenic AIV (H9N2) and one of the predominant AIV isolated from poultry farms in Korea. In antigenicity tests, the ADL0401 and MS96 virus have no significant antigenic difference. In inactivation tests, the ADL0401 isolates can be easily inactivated with $0.1\%$ Formalin at $37^{\circ}C$ within 1 hour with a little decrease of HA titer. The vaccine developed in the present report has no harmful effect on bird and forms good immune capability. Therefore, the isolates, ADL0401 can be used for a killed vaccine which can reduce the clinical signs and viral shedding in the birds infected with H9N2 low pathogenic AIVs.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.204-212
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• 2013

This study analyzed the occurrence of tunic softness, survival rate, metabolic rate and histopathologic changes arising from the effect of hypoxic environment in order to find the causes of occurrences of tunic softness, which manifests as the key phenomenon of mass mortality of Halocynthia roretzi. Regarding the survival of H. roretzi with reduction in dissolved oxygen, all the entities died on the 4th day of exposure to the dissolved oxygen concentration of $2mg\;L^{-1}$ while 50% mortality was observed on the 5th day of exposure to the dissolved oxygen concentration of $3mg\;L^{-1}$. Therefore the 5 days-$LC_{50}$ was found to be $3.55mg\;L^{-1}$ (1.86~$4.96mg\;L^{-1}$). However, occurrence of tunic softness was not observed during the period of exposure to low oxygen concentration. The oxygen consumption rate significantly decreases at the dissolved oxygen concentration of less than $5mg\;L^{-1}$ in comparison to the control group. Therefore, it is presumed that H. roretzi controls the respiration rate for prescribed period of time when exposed to hypoxic environment. Regarding the histopathologic changes in the gill, digestive gland and cyst of H. roretzi due to hypoxic environment, necrosis of epithelial layer, in filtration of blood cells, and condensation of nucleus that compose each of the organs were observed. Regarding morphological changes, the decrease in volume with shrinking of the tunic, discoloration of the internal organs and necrosis of gill and hepatopancreas were observed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.1
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• pp.59-68
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• 1994

The effects of silt and clay, water temperature and salinity on the metabolic activities: rates of respiration, filtration and nitrogen excretion in the clam, Mactra veneriformis, were investigated in ranges of $0{\sim}250ppm,\;15{\sim}25^{\circ}C\;and\;10{\sim}30\%0$ respectively. The weight specific respiration rate decreased with shell length and significantly declined at lower temperatures and lower salinity levels. Average respiration rates, filtration rates and ammonia excretion rates of the clam groups declined as water temperature was lowered. The respiration rate(R) and the filtration rate(F) decreased as the concentration of silt and clay(C) increased, the relationships between the two parameters were expressed as a regression line, R=a+b LogC and LogF=a+b LogC, respectively. On the rearing experiment treated with 50ppm of silt and clay, the relationship between the accumulative mortality(M) and the elapsed day(T) was $M=0.0186T^{2.7965}$, and the median lethal time was calculated at 16.8 days. From the rearing experiment, both rate of respiration and ammonia nitrogen excretion of experimental groups and control groups decreased with elapsed days, the rates of experimental groups, especially declined more compared with those of the control groups.

• Journal of fish pathology
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• v.8 no.2
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• pp.99-109
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• 1995

The diseased larvae of the flounder, Paralichthys olivaceus, were sampled several times from a fish hatchery located in Cheju Island between December, 1991 and April, 1992. They turned out to be infected with Vibrio sp. and diagnosed as intestinal necrosis of flounder larvae(INFL) based on morphological, biological, and biochemical examinations. INFL was known to be caused by the live food organism infected with Vibrio sp. The optimal growth conditions of the isolates for temperature, pH, and NaCl concentration were $20\sim30^{\circ}C$, 6~8, and 2~4%, respectively. In the drug sensitivity test, the isolates were sensitive to oxytetracycline, nalidixic acid, kanamycin, and novobiocin, but resistant to ampicillin, erythromycin, spiramycin and sulfa-drug.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.9
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• pp.1881-1888
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• 2011

Red tide is a natural phenomenon to bloom harmful algal, which fish and shellfish die en masse. Red tide damage with respect to sea farming has been occurred each year. Red tide damage can be minimized by means of prediction of red tide blooms. Red tide prediction using naive bayes classifier can be achieve good prediction results. The result of naive bayes method only determine red tide blooms, whereas the method can not know how increasing of red tide algae density. In this paper, we proposed the red tide blooms prediction method using fuzzy reasoning and naive bayes classifier. The proposed method can enhance the precision of red tide prediction and forecast the increasing density of red tide algae.

• Journal of Aquaculture
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• v.17 no.1
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• pp.24-29
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• 2004

The high mortality of cultured turbot, Scophthalmus maximus was occurred from Gochang in June, 2003. Infect fish with iridovirus showed a lower feed intake and lethargic. These fish exhibited pale body color, extended abdominal and exophthalmus. Histopathological studies showed basophilic enlarged cells from kidney, spleen, gill, heart, muscle, stomach, intestine, liver and pancreas of these fish. In PCR amplification with red sea bream iridovirus (RSIV) specific primer set of a DNA fragment of 286 bp was obtained from infect turbot with the virus. The strain showed the high homologies with RSIV, LBIV (largemouth bass iridovirus), GSIV (giant seaperch iridovirus) and SBIV (sea bass iridovirus).