• The Journal of Fisheries Business Administration
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• v.47 no.4
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• pp.1-13
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• 2016

Fish mortality is the most important success factor in aquaculture management. To analyze the effect of mortality considering biological and economic condition is a important problem in land-based aquaculture. This study is aimed to analyze the effect of mortality for duration of cultivation in land-based aquaculture. This study builds the mathematical model that finds the value of decision variable to minimize cost that sums up the water pool usage cost, sorting cost, fingerling cost and feeding cost under critical standing corp constraint. The proposed mathematical model involves many aspects, both biological and economical: (1) number of fingerlings (2) timing and number of batch splitting event, based on (3) fish growth rate, (4) mortality, and (5) several farming expense. Numerical simulation model presented here in. The objective of numerical simulation is to provide for decision makers to analyse and comprehend the proposed model. When extensive biological and cost data become available, the proposed model can be widely applied to yield more accurate results.

• Journal of applied mathematics & informatics
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• v.26 no.1_2
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• pp.15-27
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• 2008

We present and discuss an algorithm for the numerical solution of initial value problems of the form $D_*^\alpha$y(t) = f(t, y(t)), y(0) = y0, where $D_*^\alpha$y is the derivative of y of order $\alpha$ in the sense of Caputo and 0<${\alpha}{\leq}1$. The algorithm is based on the fractional Euler's method which can be seen as a generalization of the classical Euler's method. Numerical examples are given and the results show that the present algorithm is very effective and convenient.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.608-609
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• 2008

An alternator which converts mechanical rotating energy into electric energy is an important component of a vehicle. It operates in broad range from 3000 RPM to 18000 RPM. So, sufficient flow rate and low noise are needed in such broad operating range for a cooling fan of this alternator. In current study, the cooling fan of an alternator is developed through DFSS process and numerical analysis. In order to calculate flow rate and noise level, SC/Tetra and FlowNoise S/W are used respectively, for a new developed fan, compared with original model, numerical result shows 3 dBA reduction and measured value shows 4 dBA reduction.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.43-51
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• 1999

The power flow calculations(PFc) are the most important and powerful tools in power systems engineering. The conventional power flow problem is solved generally with numerical methods such as Newton-Raphson(NR). The conventional numerical method generally have some convergency problem, which is sensitive to initial value, and numerical stability problem concerned with jacobian matrix inversion. This paper presents a new PFc algorithm based on the improved genetic algorithm (IGA) which can overcome the disadvantages mentioned above. The parameters of GA, with dynamical hierarchy of the coding system, are improved to make GA a practical algorithm in the problem of real system. Some case studies with test bus system also present to show the performance of proposed algorithm. The results of proposed algorithm are compared with the results of PFc obtained using a conventional NR method.

• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.477-488
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• 2000

A distance measure between two Latin-hypercube designs is defined and its expected value is computed. It was computed by using mathematical statistics, numerical analysis (multidimensional numerical integration), Monte-carlo method, and the theory of asymptotic normal distribution. For the comparison of two Latin-hypercube designs with same structure but different randomness, the difference of expected values of response function and information mass of experimental designs are considered. These methods may be useful in comparison between two general experimental designs.

• Selected Papers of The Society of Naval Architects of Korea
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• v.2 no.1
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• pp.63-78
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• 1994

This paper deals with the treatment of the open boundary in two-dimensional free-surface wave problems. Two numerical schemes are investigated for the implementation of the open boundary condition. One is to add the artificial damping term to the dynamic free-surface boundary condition, in which the determination of suitable damping coefficient and the damping zone is the most important. The other is a modified Orlanski's method, which is known to be very useful for the uni-directional waves. Using these two schemes, numerical tests have been conducted for a few typical free-surface wave problems. To obtain the numerical solution of the free-surface boundary value problem, the fundamental source-distribution method is used and the fully nonlinear free-surface boundary conditions are applied. The computed results are presented in comparison with those of others for the proof of practicality of these two schemes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.394-402
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• 2009

To investigate the heavy-weight impact noise of apartment houses, numerical analysis was performed. The analysis acoustic pressure consider acoustic mode by finite element method. The variables considered effecting on the acoustic pressure are the Acoustic mode, acoustic damping, and the impulse load. The heavy-weight impact noise is a changeable value in the room. Since the most part of the frequency component of heavy-weight impact noise has low frequency. The noise in low frequency is related to the vibration of structure, the reflection of acoustic wave caused by wall and the standing wave called by acoustic mode. The prediction by the numerical analysis was verified with test result of the heavy weight-impact noise at apartment houses.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.137-142
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• 2008

The purpose of the present study is to investigate the convective heat transfer characteristics and the validity of fin efficiency of the circular finned-tube heat exchanger by using commercial CFD code. The heat transfer coefficient obtained by using the laminar model was 22% overestimated to the experimental data. The fin surface temperature compared with the experimental data measured by the liquid crystal method. The fin efficiency by the present numerical experiment, defined as normalized and averaged fin surface temperature, was greater than the theoretical fin efficiency and the difference is increased at high value of the factor m.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.233-238
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• 2008

An alternator which converts mechanical rotating energy into electric energy is an important component of a vehicle. It operates in broad range from 3000 RPM to 18000 RPM. So, sufficient flow rate and low noise are needed in such broad operating range for a cooling fan of this alternator. In current study, the cooling fan of an alternator is developed through DFSS process and numerical analysis. In order to calculate flow rate and noise level, SC/Tetra and Flow Noise are used respectively, for a new developed fan, compared with original model, numerical result shows 3 dBA reduction and measured value shows 4 dBA reduction.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.2
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• pp.150-155
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• 2017

Many engineering issues are caused because of sloshing phenomena. Numerical solution methods including the computational fluid dynamics (CFD) technique, are used to analyze these sloshing problems. In this study, a numerical technique was used to analyze sloshing impact loads in a prismatic tank under forced horizontal motion. The volume-of-fraction (VOF) method was adopted to model the sloshing flow. Six cases were used to compare the effects of the natural frequencies of a simple rectangular and prismatic tank, with impact pressure on the prismatic tank wall. This study also investigated the variable pressure loads and sloshing phenomena in prismatic tanks when the frequencies were changed. The results showed that the average of the peak pressure value for ${\omega}^{\prime}1=4.24=4.24$ was 22% higher than that of ${\omega}_1=4.6$.