• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1519-1534
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• 2016

In this paper, we study how to optimize the data shuffle phase by leveraging the flow relationship in datacenter networks (DCNs). In most of the clustering computer frameworks, the completion of a transfer (a group of flows that can enable a computation stage to start or complete) is determined by the flow completing last, so that limiting the rate of other flows (not the last one) appropriately can save bandwidth without impacting the performance of any transfer. Furthermore, for the flows enter network late, more bandwidth can be assigned to them to accelerate the completion of the entire transfer. Based on these characteristics, we propose the flow chasing algorithm (FCA) to optimize the completion of the entire transfer. We implement FCA on a real testbed. By evaluation, we find that FCA can not only reduce the completion time of data transfer by 6.24% on average, but also accelerate the completion of data shuffle phase and entire job.

• 한국물환경학회지
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• 제21권1호
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• pp.79-83
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• 2005

Foraging behaviour of false dace, Pseudorasbora parva, was investigated in water flowing at various velocities with the existence of a cavity for rest. The pursuit comprised three succeeding processes such as, approaching, chasing and attacking. Angles between the fish body and the water flow direction and swimming speeds increased in the latter stages of approaching, chasing and attacking. All pursuit angles, swimming speeds and distances increased with flow velocity and peaked at the flow velocity of 7 cm/sec. At higher velocities, however, the fish avoided the use of much energy against the large drag force. The probability of capture and the feeding rate steadily decreased with increasing flow velocity. Under the fast flow, the fish adjusted their swimming speed to get the optimum velocity relative to the flowing water for the energetic budget. Fish spent more time in the cavity as flow velocity increased to avoid the energy expenditure necessitated by the high velocity.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.6534-6542
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• 2015

본 연구에서는 4개 뮤추얼펀드 유형을 대상으로 한국시장에서의 펀드 성과와 펀드 현금흐름 간의 관계를 분석하였다. 주별 및 월별 자료를 사용한 분석결과는 다음과 같다. 첫 번째, 양자 간의 관계는 펀드의 유형에 따라 다르게 나타나고 있으며, 같은 주식형 펀드인 일반주식형 펀드와 인덱스형 펀드 역시 다른 결과를 보여주고 있다. 두 번째, 양자 간의 관계는 펀드시장의 구조변화 이전/이후 기간에서 다른 양상을 보여 시장의 구조변화가 동 관계에 무시할 수 없는 영향을 미쳤음을 보여주었다. 세 번째, 수익률을 추구하는 현금흐름(return chasing flow)은 채권형 펀드에서 가장 강하게 나타났으며, 일반주식형펀드 및 MMF에서는 구조변화 이후 기간에서만 나타났다. 그러나 인덱스형 펀드에서는 전혀 관측되지 않았다. 네 번째, 펀드현금흐름이 향후의 펀드 성과에 미치는 영향은 오직 MMF에서만, 그리고 구조변화 이후의 기간에서만 관측되었다.

• 산업경영시스템학회지
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• 제20권43호
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• pp.1-16
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• 1997

This paper improves the autonomy for supplier's schedule and the flexibility of the final assembly line. The final assembly line is a single work station and each product taking different assembly time is considered. In the assembly schedule, the heuristic method based on the goal chasing method is used. Consequently, suppliers can independently determine their output rates and thus, change their workload pattern according to their needs and priorities. Moreover, this flexibility can help to avoid expensive final-assembly-line stoppages in case of sudden part supply disruptions. The sequencing method can be easily implemented into an existing just-in-time system. In addition, the mathematical model was formulated and the algorithm was explained through the flow chart. The numerical example was given and the efficiency of this method is shown through the analysis of computational results of that example.

• 대한조선학회논문집
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• 제54권6호
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• pp.470-475
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• 2017

Since the intake air of gas turbine engine of marine purpose contains water particles, inertial separator for separating the air and water particles are provided. Saw type and wave type separator are now used to separate inflow water particle from the gas. In this paper, the design parameters of saw type separator are studied by numerical simulations. Using the commercial CFD program, Star-CCM+, Lagrangian-Eulerian method was used to perform the analysis of two phase flow of the mist in the air. This method solves Reynolds-Averaged Navier-Stokes equations in Eulerian framework for the continuous phase, while solves equation of motion for individual particles in Lagrangian framework. Lagrangian multiphase method was applied to monitor the particles of different sizes and shapes and to verify collision between particles by chasing particles. Water particles were injected through injectors located at the inlet of the separator and escape mode was used which assumes that the particles attached on the surface of inertial separator were removed from the simulation, effectively escaping the solution domain. Through the numerical computations with the inlet condition of constant water particle size in the wetness fraction of 85%, efficiency of eliminating the water particle and the pressure drop between the inlet and outlet were examined.