• Journal of the Korean Solar Energy Society
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• v.36 no.5
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• pp.73-89
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• 2016

To assure maximum economic benefits and the energy performance of solar water heating systems, the proper sizing of components and operating conditions need to be optimized. In recent years, a number of studies to design optimally solar water heating systems have been tried. This paper presents a design method for optimizing the various capacity-related and installation-related design variables based on life cycle cost using a genetic algorithm. The design variables considered in this study included the types and numbers of solar collector and auxiliary heaters; the types of storage tanks and heat exchangers; the solar collector slope; mass flow rates of the fluid on the hot and cold sides. The suggested method was applied for optimizing a solar water heating system for an elementary school in Seoul, South Korea. In addition, the effectiveness of the proposed optimization method was assessed by analyzing the obtained optimal solutions of six case studies, each of which was simulated with different solar fractions. It is observed that a trade-off between the equipment cost and the energy cost results in an optimal design that yields the lowest life cycle cost. Therefore, it could be helpful to apply the optimal solar water heating system by comparing the various design solutions obtained by using the optimization method instead of the engineer's experience and intuition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.695-702
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• 2012

In this study, Multi-fidelity analysis is performed to improve the accuracy of analysis result during conceptual design stage. Multidisciplinary Design Optimization(MDO) method is also considered to satisfy the total system requirements. Low-fidelity analysis codes which are based on empirical equations are developed and validated for analyzing the Unmanned Aerial Vehicle(UAV) which have unconventional configurations. Analysis codes consist of initial sizing, aerodynamics, propulsion, mission, weight, performance, and stability modules. Design synthesis program which is composed of those modules is developed. To improve the accuracy of the design method for UAV, Vortex Lattice Method is used for the strategy of MFA. Multi-Disciplinary Feasible(MDF) method is used for MDO technique. To demonstrate the validity of presented method, the optimization results of both methods are compared. According to those results, the presented method is demonstrated to be applicable to improve the accuracy of the analyses during conceptual design stage.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1511-1518
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• 2017

Renewable energy hybrid systems look into the process of choosing the finest arrangement of components and their sizing with suitable operation approach to deliver effective, consistent and cost effective energy source. This paper presents hybrid renewable energy system (HRES) solar photovoltaic, downdraft biomass gasifier, and fuel cell based generation system. HRES electrical power to supply the electrical load demand of academic research building sited in $23^{\circ}12^{\prime}N$ latitude and $77^{\circ}24^{\prime}E$ longitude, India. Fuzzy logic programming discover the most effective capital and replacement value on components of HRES. The cause regarding fuzzy logic rule usage on HOMER pro (Hybrid optimization model for multiple energy resources) software program finds the optimum performance of HRES. HRES is designed as well as simulated to average energy demand 56.52 kWh/day with a peak energy demand 4.4 kW. The results shows the fuel cell and battery bank are the most significant modules of the HRES to meet load demand at late night and early morning hours. The total power generation of HRES is 23,794 kWh/year to the supply of the load demand is 20,631 kWh/year with 0% capacity shortage.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.110-117
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• 2009

This paper introduces a case study for efficient generation of production schedules in a tube manufacturing system. The considered scheduling problem consists of two sub problems : lot sizing for a job and Job sequencing. Since these problems require simulation optimization in which the performance measures are obtained by simulation execution, the trade-off between solution quality and computation time is an important issue. In this study, the optimal lot size for every product type is determined from simulation experiments. Then, target production quantity for each product type is transformed to several jobs such that a Job consists of determined lot size. To obtain the good solution for a Job sequence in a reasonable time, a number of alternatives are generated from heuristic rules developed by intuition and analysis of the considered system, and a job sequence is selected from simulation experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.2
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• pp.83-91
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• 2003

Pantograph design Process must be considered in terms of stability of aerodynamics and reduction of aeroacoustics. Furthermore pantograph needs to be insensible to severe circumstance condition like typhoon, tunnel, a change of season. In this paper, robust design of panhead sections is conducted based on the Taguchi's design of experiment method. In the aeroacoustic noise analysis, an acoustic analogy using the Ffowcs Williams and Hawkings(FW-H) equation is used to calculate the flow induced sound pressure level in aeroacoustics. From the near-field CFD analysis data, the far-field noise is predicted at the positions of 25 m away from Pantograph. Based on aerodynamic(CFD) and aeroacoustic(FW-H) analysis data, the optimal sizing and Positioning of panhead elements are determined using robust design optimization method. Design parameters such as thickness, length and radius are controllable factors, while outdoor air temperature and atmospheric pressure are considered as uncontrollable factors in the context of Taguchi's approach. A number of CFD simulation and aeroacoustic analysis are performed based on orthogonal arrays. In this paper, two-step optimization method is used as a parameter design procedure. It is executed using signal to noise(S/N) ratio and analysis of means(ANOM) method. So Thus, an optimal level of design parameters Is extracted to minimize the disconnection ration between contact strips and catenary system, and reduce the far-field aeroacoustic noise.

• Computational Structural Engineering
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• v.9 no.3
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• pp.179-186
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• 1996

A simple nonlinear programming(NLP) formulation for the optimal topology problem of structures is developed and examined. The NLP formulation is general, and can handle arbitrary objective functions and arbitrary stress, displacement constraints under multiple loading conditions. The formulation is based on simultaneous analysis and design approach to avoid stiffness matrix singularity resulting from zero sizing variables. By embedding the equilibrium equations as equality constraints in the nonlinear programming problem, we avoid constructing and factoring a system stiffness matrix, and hence avoid its singularity. The examples demonstrate that the formulation is effective for finding an optimal solution, and shown to be robust under a variety of constraints.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.131-137
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• 2009

This presents the equivalent circuit model of solar cell with irradiation and temperature condition. Based on solar cell model, the photovoltaic module specification of manufacturer compare with photovoltaic module simulation and is investigated by simulation results. The obtained results indicate that residual of simulation value and specification value about photovoltaic module is lower. There is considerable validity in simulation of photovoltaic module. Thus, the optimum simulation of photovoltaic module array are studied in this paper. This paper propose the sizing optimization of photovoltaic module array for stand-alone photovoltaic system. Also, the proposed stand-alone photovoltaic system is setting in special region(in seoul). This paper presents simulation characteristic of optimization output power in seoul.

• Design & Manufacturing
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• v.6 no.2
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• pp.6-11
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• 2012

A counter shaft gear is an important part in the transmission system of vehicle. Its shape is relatively complicated and should meets high strength. Traditionally the counter shaft gear has been manufactured as follows; a spline body is firstly machined for teeth and then attached to the main gear body by frictional welding, and finally is finished by grinding. Therefore it is necessary to develop a new manufacturing technology eliminating both frictional welding and grinding processes. In this study, a new hot forging process was proposed and designed so that the spline body with teeth and main gear body are formed as one body. Finite element simulations and experimental works were peformed for design of forging processes to get the quality final precision-forged product. Consequently the most suitable blocker process could be obtained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.81-87
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• 1998

In this paper, a global acoustic design sensitivity analysis (DSA) of field point pressure with respect to structural sizing design variables is developed. Firstly acoustic sensitivity is formulated and implemented numerically. And it is combined with continuum structural sensitivity to obtain the global acoustic, design sensitivity. For this procedure, GASA (global acoustic design sensitivity analyzer) has been developed. A half scale of automobile cavity model is considered in this paper. In order to confirm accuracy of the results of global acoustic DSA obtained by GASA, it is compared with the result of central finite difference method. In order to reduce computation time, Rayleigh approximated solution is evaluated and compared with the solution which used every nodal velocities. Also the acoustic optimization procedure is performed using design sensitivities. From these numerical studies, it can be shown that global acoustic DSA is a useful tool to improve acoustic problems.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.4
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• pp.294-300
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• 2004

This paper considers a trade-off effect between in-house storage space and leased storage space in generic warehouses operated under a randomized storage assignment policy. The amount of in-house storage space is determined based on the law of large numbers satisfying a given service level of protection against space shortages. Excess space requirement is assumed to be met via leased storage space. A new analytic model is formulated for determining the excess space such that the total cost of storage space is minimized. Finally, computational results are provided for the systems where the standard economic-order-quantity inventory model is used for all items.