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        검색결과 45

        41.
        2008.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper focuses on the mackerel's visual ability and swimming capability, and aims to describe the behavior in capture and escape process by trawl. The visual sensory systems and reaction behavior based locomotory capability were analyzed and simulated. The ability of fish to see an object depends on the light intensity and the contrast and size of the object. Swimming endurance of the fish is dependent on the swimming speed and the size of the fish. Swimming speeds of the fish are simulated 3 types of the burst speed, the prolonged speed and the sustained speed according to the time they can maintain to swim. The herding and avoiding is typical reaction of the fish to the stimuli of trawl gear in the capture process. These basic behavior patterns of the virtual mackerel to the gear are simulated. This simulation will be helpful to understand the fishing processes and make high selectivity of fishing.
        4,000원
        42.
        2007.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper discusses a scheduling problem on object-oriented developments over multiple teams with limited resources in matrix organization. The objective of the problem is to minimize the makespan of overall projects. There are tangible and intangible advantages such as efficient resource share, improvement of productivity, development efforts and cost reduction, etc. by dispatching resources properly to the development teams. Traditionally, the project scheduling has been done with a manager's intuition or heuristic. We present a scheduling model with illustrative examples, stochastic search approach, and apply a variety of problems generated randomly to the approach. The results are analysed.
        4,300원
        43.
        2007.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Otter boards in the trawl are the one of essential equipments for the net mouth to be spread to the horizontal direction. Its performance should be considered in the light of the spreading force to the drag and the stability of towing in the water. Up to the present, studies of the otter boards have focused mainly on the drag and lift force, but not on the stability of otter boards movement in 3 dimensional space. In this study, the otter board is regarded as a rigid body, which has six degrees of freedom motion in three dimensional coordinate system. The forces acting on the otter boards are the underwater weight, the resistance of drag and spread forces and the tension on the warps and otter pendants. The equations of forces were derived and substituted into the governing equations of 6 degrees of freedom motion, then the second order of differential equations to the otter boards were established. For the stable numerical integration of this system, Backward Euler one of implicit methods was used. From the results of the numerical calculation, graphic simulation was carried out. The simulations were conducted for 3 types of otter boards having same area with different aspect ratio(λ=0.5, 1.0, 1.5). The tested gear was mid-water trawl and the towing speed was 4k't. The length of warp was 350m and all conditions were same to each otter board. The results of this study are like this; First, the otter boards of λ=1.0 showed the longest spread distance, and the λ=0.5 showed the shorted spread distance. Second, the otter boards of λ=1.0 and 1.5 showed the upright at the towing speed of 4k't, but the one of λ=0.5 heeled outside. Third, the yawing angles of three otter boards were similar after 100 seconds with the small oscillation. Fourth, it was revealed that the net height and width are affected by the characteristics of otter boards such as the lift coefficient.
        4,500원
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