• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.358-367
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• 1983

Antibiotic-resistant strains of Salmonella typhimurium and Klebsiella pneumoniae died readily after their addition to raw sewage, but they grew in sterilized sewage. The decline was not a result of antibiotic stresses, and because the bacteria were able to survive in large numbers for at least 15 days in solutions containing no organic nutrients, it was not a result of competition. Toxin production, bacteriophages, and Bdellovibrio did not cause the disappearance of the two bacterial species. A decline was also evident if the sewage was first passed through a $3-{\mu}m$ filter or treated with cycloheximide or cycloheximide plus nystatin, but protozoa developed under these conditions. Little or no decline occurred if the sewage was filtered and treated with the eucaryotic inhibitors before adding S. typhimurium or K. pneumoniae, and protozoa were not detected. S. typhimurium increased in abundance if cycloheximide, streptomycin, and erythromycin or large amounts of glucose were added to sewage. Tetrahymena thermophilus did not significantly reduce the population of S. typhimurium in buffer when the density of the bacterium was about $10^4/ml$. However, when more than $10^8$ Enterobacter agglomerans cells per ml were added to the buffer, T. thermophilus reduced the abundance of E. agglomerans and S. typhimurium to $10^6$ and 10/ml, respectively. The density of S. typhimurium was further decreased by a second increment of E. agglomerans cells. The disappearance of S. typhimurium and K. pneumoniae from sewage thus is the result of predation by protozoa. It is proposed that predators will eliminate a prey species from a natural environment when an alternate prey is present at concentrations above the threshold number for active feeing by the predator and when the rate of growth of the prey is less than the rate of predation.

• Journal of KIISE:Software and Applications
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• v.32 no.4
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• pp.277-289
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• 2005

To overcome the long design time/high computational effort/low computational performance of phylogenetic learning featuring selection and reproduction, this paper proposes a genetic representation based on XML. Since genetic programs (GP) and genetic operations of this representation are maintained by the invocation of the built-in off-the-shelf XML parser's API, the proposed approach features significant reduced time consumption of GP design process. Handling only semantically correct GPs with standard XML schema can reduce search space and computational effort. Furthermore, computational performance can be improved by the parallelism of GP caused by the utilization of XML, which is a feasible system and wire format for migration of genetic programs in heterogeneous distributed computer environments. To verify the proposed approach, it is applied to the evolution of social behaviors of multiple agents modeling the predator-prey pursuit problem. The results show that the approach can be applied for fast development and time efficiency of GPs.

• Journal for History of Mathematics
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• v.26 no.2_3
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• pp.197-210
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• 2013

The late 18C Malthus studied population growth for the first time, Verhulst the logistic model in 19C and, after that, the study of the predation competition between two species resulted in the appearance of Lotka-Volterra model and modified model supported by Gause's experiment with bacteria. Instable coexistence equilibrium being found, Solomon and Holling proposed functional and numerical response considering limited abilities of predator on prey, which applied to Lotka Volterra model. Nicholson and Baily, considering the predation between host and parasitoid in discrete time, made a model. In 20C there were developed various models of disease dynamics with the help of mathematics and real data and named SIS, SIR or SEIR on the basis of dynamical phenomena.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.493-504
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• 2008

In the seas around the Korean Peninsula, the seasonal cycle of zooplankton related to North Pacific regime shifts was investigated to understand the reaction of the ecosystem to climate change using long-term data on zooplankton biomass (1965-2000) and the abundance of four major zooplankton groups: copepods, amphipods, chaetognaths, and euphausiids (1978-2000). In general, the zooplankton biomass showed a large peak in spring and a small peak in autumnin Korean waters, but there was a slight difference in the peak time depending on the location and the period before and after the North Pacific regime shift. The zooplankton biomass showed conspicuous seasonal peaks in R-III (1990-2000) compared to R-I (1965-1976) and R-II (1977-1988), and the seasonal peak shifted from the autumn in R-II to the spring in R-III. The peak of copepods and euphausiids in abundance was from April to June, while chaetognaths peaked from August to October. We postulate that the time lag between the peaks for copepods and chaetognaths results from the predator-prey relationship. The regime shift in 1989 did not alter the seasonal cycle of the four major zooplankton groups, although it enhanced their production. The seasonal peaks of the four major zooplankton groups did not shift, while the seasonal peaks of the zooplankton biomass did shift. This was not only becausethe zooplankton biomass included other mesozooplankton groups but also because the abundance of the four major zooplankton groups increased significantly in spring.

• Journal of Aquaculture
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• v.12 no.2
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• pp.101-105
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• 1999

Predater, tarpon (Megalops atlanticus) has a specific preferring preys in natural environments. To investigate this, young tarpon were captured and their stomach contents were weighed and sorted based on taxonomic groups. Average standard length and body weight for tarpon captured were 11.49 cm and 34.67 g, respectively. The average weight of the stomach contents in the tarpon was 0.83 g. The status of digestion extent of the consumed preys was 2.37 which indicated that preys were relatively well digested. The main preys in tarpon stomach were other fishes (mosquito fish and sheepshead minnow) and shrimp. Frequency occurrence of fishes in tarpon stomach was highest (P＜0.05). Also, frequency occurrence of shrimp was higher than that of fly (P＜0.05). Mean individual number of fish found in tarpon stomach was 2.66 per tarpon and it was higher than that of shrimp or fly (P<0.05). There was linear regression between the total weight of the consumed preys and the standard length of tarpon; Y (Total weight of preys) = 0.3151 $\times$ (Standard length of tarpon) - 2.7123, $R^2$=0.6140. Also, there was the strong linear regression between the total weight of the consumed preys and weight of the tarpon; Y (Total weight of preys) = 0.0299 $\times$ (Body weight of tarpon) - 0.0774, $R^2$=0.7882. These results indicated that the main preys for young tarpon in their natural environments were small fish composed of mosquito fish and sheepshead minnow and shrimp. And there was the stronger correlation between the total weight of preys and the body weight of tarpon than that between the total weight of preys and the standard length of tarpon.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.3
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• pp.230-236
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• 1987

The correlation between tintinnid and dinoflagellate by means of seasonal variation of standing crops was investigated at two selected stations in Masan Bay, well-known as a red tide zone in southern coastal waters of Korea, during the period from January 1981 to December 1982. The most dominant dinoflagellates mainly belonged to $20-60\;{\mu}m$ of size class, and Gymnodinium and Prorocentrum were predominant from spring to summer season. Of tintinnid, Favella spp. were most dominant and associated with dinoflagellate blooms at the same season. Especially, Favella spp. were most positively correlated with $40-60\;{\mu}m$ size class of dinoflagellate, and also represented higher multiple corrleation with outer station (St.2), comprising relatively large species of Gymonodinium and Protogonyaulax, than with inner station (St. 1), dominated by Prorocentrum blooms. Thus, the interspecific food selection by size and morphology between tintinnid including Favella and dinoflagellate is recognized and it is considered to be an important factor influenecing on the prey-predator relationship in lower trophic level in the surveyed area.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.234-242
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• 1995

The functional responses of the female Cyrtorhinus lividipennis on brown planthopper (BPH), Nilaparvata lugens, eggs and their predation behavior were investigated at six temperature conditions; 20, 23, 26, 29, 32, and $35^{\circ}C$. C. lividipennis was found to prefer young BPH eggs, especially 3-day-old eggs the most. The functional responses for female C. lividipennis on BPH eggs fitted the Holling's Type-I true predator-prey Rogers' (1972) model at all temperatures tested except $35^{\circ}C$ at which the negative Th value was produced. With the temperature increased up to 32$^{\circ}C$, the instantaneous attacking rate(a) increased from 0.1923 at $20^{\circ}C$ to 0.5085 at $32^{\circ}C$, while the handling time (Th) was gradually decreased as low as 0.0151 at $32^{\circ}C$. C. lividipenis preferred the BPH eggs laid on the upper part of rice stem when the BPH egg density was high, but there was no significant difference in the preference when the egg density was low. The preference was more obvious in high temperature conditions such as above 29$^{\circ}C$.

• Korean journal of applied entomology
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• v.38 no.1
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• pp.29-33
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• 1999

Orius strgicollis Poppius is an endemic natural enemy of thrips recently found. To estimatethe optimum temperature for rearing in laboratory, development and oviposition of 0. strigicollis wasstudied at 15, 20, 25 and 30$^{\circ}$C with a 16L : 8D photoperiod and 60-80% RH. Cotton aphid, Aphisgossipyii, was supplied as prey. Total number of eggs laid per female ranged from 39.1 to 68.5 with thehighest at 25$^{\circ}$C. Adult longevity decreased as temperature increased, and the reverse was true for eggsurvivorship. Survivorship of larvae was 26.7,43.3, 76.7 and 46.7% at 15, 20, 25 and 30$^{\circ}$C, respectively.Duration of eggs and larvae at tested temperatures ranged from 3.4 days to 18.9 days and from 9.4 days to45.6 days, respectively. A linear regression model could describe development of the predator as afunction of temperature (R2=0.949-0.997). The lower developmental threshold temperatures for egg,larvae, and total immature stage were estimated to be 12.4, 11.4, and 11.6"C, respectively.6"C, respectively.vely.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.637-643
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• 2015

The diet composition of juvenile Trachurus japonicus were studied using 195 specimens collected from 2013 (May, June, July, and September) to 2014 (May, June, and July) in the coastal waters of Geumodo, Yeosu, Korea. The size of juvenile T. japonicus ranged from 4.3 to 15.2 cm in body length (BL). Juvenile T. japonicus was carnivorous and crustaceans predators that consumes mainly consumed copepods. Its diet also included small quantities of decapods, cirripedians, nematods, chaetognathans, fishes, amphipods, cumaceans, ostracods and euphausiids. The graphical method for feeding strategy revealed that juvenile T. japonicus is an opportunistic and specialized predator on copepods, especially Corycaeus. affinis, and showed narrow niche width. Juvenile T. japonicus showed ontogenetic diet change. Small size group individuals (4.3-8.0 cm BL) mainly consumed copepods. The portion of this prey item decreased in the large size group (8.0-15.2 cm BL), and this decrease was paralleled with increased consumption of decapods.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.41-46
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• 2016

The feeding habits of juvenile (14.0~29.0 mm SL) of Gymnogobius heptacanthus were examined based on 229 individuals, that collected from June to August 2011 in the coastal water of Geoje, Korea. G. heptacanthus fed mainly on copepods which constituted 96.74% in IRI. Barnacle larvae were the second largest dietary component. Its diet also included small quantities of tintinnids, cladocerans and decapods. Graphical analysis of the diet composition showed that G. heptacanthus is a specialized predator characterized by strong individual feeding specialization. Especially copepods were heavily selected by of juvenile G. heptacanthus regardless of prey availability.