• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.505-510
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• 2004

The feeding habits of brown barracuda (Sphyraena pinguis) were analyzed using the stomach contents of monthly samples collected from coastal waters of Gadeok-do, Korea from January to December, 1998. Brown barracuda occurred mainly from summer to autumn in the study area, and ranged from 15 to 35 cm in standard length. Brown barracuda was a piscivorous fish which, mainly consumed teleost fish such as anchovy (Engranlis japonicus) and chefoo thryssa (Thfssa kammalensis). Its diet also included small quantities of shrimp and cephalopods. Although smaller fishes (<25 cm SL) consumed shrimp and cephalopods as well as fish, larger fishes (>30 cm SL) consumed exclusively teleost fish. The prey size increased with increase of fish size.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.219-231
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• 2003

This paper aims to study the problem of combined harvesting of a system involving one predator and two prey species fishery in which the predator feeds more intensively on the more abundant species. Mathematical formulation of the optimal harvest policy is given and its solution is derived in the equiblibrium case by using Pontryagin's Maximum principle. Dynamic optimization of the harvest policy is also discussed by taking E(t), the combined harvest effort, as a dynamic variable. Biological and bioeconomic interpretations of the results associated with the optimal equilibirum solution are explained. The significance of the constraints required for the existence of an optimal singular control are also given.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.285-288
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• 2000

본 논문에서는 다중 에이전트(multi-agent) 환경에서 에이전트들의 행동을 효율적으로 조정 (coordination)하기 위해 강화 학습(reinforcement learning)을 이용하였다. 제안된 방법은 각 에이전트가 목표(goal)와의 거리 관계(distance relationship)와 인접 에이전트들과의 공간 관계(spatial relationship)를 이용하였다. 그러므로 각 에이전트는 다른 에이전트와 충돌(collision) 현상이 발생하지 않으면서, 최적의 다음 상태를 선택할 수 있다. 또한, 상태 공간으로부터 입력되는 강화 값이 0과 1 사이의 값을 갖기 때문에 각 에이전트가 선택한 (상태, 행동) 쌍이 얼마나 좋은가를 나타낼 수 있다. 제안된 방법을 먹이 포획 문제(prey pursuit problem)에 적용한 결과 지역 제어(local control)나. 분산 제어(distributed control) 전략을 이용한 방법보다 여러 에이전트들의 행동을 효율적으로 조정할 수 있었으며, 매우 빠르게 먹이를 포획할 수 있음을 알 수 있었다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.522-527
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• 2003

Feeding habits of Limanda yokohamae collected from the eelgrass bed in Kwangyang Bay were studied. L. yokohamae (1-16 cm SL) was a carnivore which consumed mainly polychaetes. Its diets included a significant quantity of amphipods (gammarids and caprellids) as well as small quantities of gastropods and ophiuroids. L. yokohamae showed ontogenetic changes in feeding habits. Small individuals less than 4 cm SL preyed mainly on amphipods. However, polychaetes were heavily selected with increasing fish size while the portion of the diet attributable to amphipods decreased sharply. Polychaetes were the major prey organisms for all seasons. Dietary breadth of each size class shows relatively low value, and this means that L. yokohamae depends on only few kinds of food organisms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.1
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• pp.32-38
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• 2008

We studied the feeding habits of Sebastes thompsoni based on 421 specimens obtained in monthly collections between January and December 2005 in the coastal waters off Busan, Korea. S. thompsoni was a crustacean feeder, and consumed mainly shrimp and euphausiids. Its diet also included small quantities of amphipods, cephalopods, and fish. It showed distinct ontogenetic changes in feeding habits. Smaller individuals (14-17 cm standard length (SL)), mainly consumed euphausiids. The portion of these prey items decreased with increasing fish size, and larger individuals (>20 cm SL) consumed mainly shrimp such as Leptochela sydniensis.

• Fisheries and Aquatic Sciences
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• v.10 no.3
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• pp.159-169
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• 2007

The complex 2-dimensional movements of fish during an annual migration circuit were generated and simulated by a chaotic model of fish movement, which was expanded from a small-scale movement model. Fish migration was modeled as a neural network including stimuli, central decision-making, and output responses as variables. The input stimuli included physical stimuli (temperature, salinity, turbidity, flow), biotic factors (prey, predators, life cycle) and landmarks or navigational aids (sun, moon, weather), values of which were all normalized as ratios. By varying the amplitude and period coefficients of the klinokinesis index using chaotic equations, model results (i.e., spatial orientation patterns of migration through time) were represented as fish feeding, spawning, overwintering, and sheltering. Simulations using this model generated 2-dimesional annual movements of sea bream migration in the southern and western seas of the Korean Peninsula. This model of object-oriented and large-scale fish migration produced complicated and sensitive migratory movements by varying both the klinokinesis coefficients (e.g., the amplitude and period of the physiological month) and the angular variables within chaotic equations.

• Applied Microscopy
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• v.46 no.2
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• pp.89-92
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• 2016

The bluegill Lepomis macrochirus is an invasive species, not native to Korea, introduced for aquaculture. This species is ranked as a new top predator due to its massive aquatic carnivorous and herbivorous nature by acute vision and the absence of a natural enemy. The visual cells of the retina of L. macrochirus are composed of short single cones and equal double cones and long and bulky rods by light and electron microscopes. In particular, the cones show a regular square mosaic arrangement. This pattern is widely considered as a strong predator. With regard to the visual system, this mosaic pattern may closely be related to a dynamic visual acuity to track and hunt prey.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.2
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• pp.191-199
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• 1998

Feeding habits of Lateolabrax Japonicus collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. L. Japonicus was a carnivore which consumed mainly amphipods (gammarid amphipods and caprellid amphipods), crabs, caridean shrimps and copepods. Its diets included small quantities of fishes, mysids, polychaetes, tanaids and isopods. Three distinct ontogenetic feeding groups were noted : (1) 1~2 cm SL individuals preyed heavily on copepods. (2) 2~15 cm SL individuals preyed heavily on amphipods. (3) individuals over 15 cm SL preyed heavily on crabs, caridean shrimps and fishes. L. Japonicus showed seasonal changes in prey composition. These changes were not caused by seasonal changes in food availability, but by changes in the size composition of L. Japonicus occurred in the eelgrass bed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.895-900
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• 2014

The feeding ecology of Doederleinia berycoides from the southern sea of Korea was examined. Specimens were caught monthly from January 2007 to June 2008. The size of the specimens ranged from 6.8 to 39.8cm in total length (TL). The primary prey items of D. berycoides included fishes and shrimps. In autumn, feeding mainly crustacea and fishes feeding mainly in winter. The individuals of smallest size class (less than 15 cm TL) fed mainly on crustacea. The proportion of crustacea decreased as body size increased, whereas the consumption of fishes increased. Fishes accounted for almost (86%) stomach contents of larger individuals (more than 35 cm TL).

• East Asian Journal of Business Economics (EAJBE)
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• v.2 no.2
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• pp.48-52
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• 2014

T In this paper we will observe the critical impact of the changing lifestyles and advancements in various fields of life. Terms like stress, anxiety, hyper tensions are now a days are being commonly associated with today's living patterns. Stress levels are demonstrating a very positive trend across all the demographic profiles of India. Youth is the soft target of this fatal movement. Indian youth is unable to face the challenges of demanding lives and is falling easy prey to the circumstances. There is a steep rise in youth suicide cases all across India.