• Design & Manufacturing
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• v.17 no.1
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• pp.48-55
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• 2023

In this study, on the structure simulation for manufacturing a high strength/light weight 48V battery housing for a mild hybrid vehicle was conducted. Compression analysis was performed in accordance with the international safety standards(ECE R100) for existing battery housings. The effect of plastic materials on compressive strength was analyzed. Three models of truss, honeycomb and grid rib for the battery housing were designed and the strength characteristics of the proposed models were analyzed through nonlinear buckling analysis. The effects of the previous existing rib, double-sided grid rib, double-sided honeycomb rib and double-sided grid rib with a subtractive draft for the upper cover on the compressive strength in each axial direction were examined. It was confirmed that the truss rib reinforcement of the battery housing was very effective compared to the existing model and it was also confirmed that the rib of the upper cover had no significant effect. In the results of individual 3-axis compression analysis, the compression load in the lateral long axis direction was the least and this result was found to be very important to achieve the overall goal in designing the battery housing. To reduce the weight of the presented battery housing model, the cell molding method was applied. It was confirmed that it was very effective in reducing injection pressure, clamping force and weight.

• Journal of Environmental Impact Assessment
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• v.26 no.4
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• pp.217-226
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• 2017

Although the effects of climate change are universal, Small Island Developing States (SIDS) are considered to be most vulnerable. SIDS heavily rely on imported oil and fossil fuels for electricity generation and transportation, which makes them economically vulnerable and exposed to fluctuating oil price. Among the reasons SIDS highly depend on diesel fuel is due to the dispersed population living in remote islands which means, providing electricity through on on-grid system is difficult. Fiji as one of the SIDS, has actively promoted renewable sourced energy through a national plan to mitigate the impacts of climate change. In order to determine how feasible implementing a renewable energy (RE) system will be in Fiji, this study chose a remote island called Mavuva Island to test application of a hybrid RE system using HOMER. A combination of energy storage system (ESS), solar photovoltaic (PV) and diesel generator turns out to be the most cost effective and optimal configuration, resulting in effective greenhouse gas reduction for the given region.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.381-389
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• 2020

This study analyzed the optimal electricity cost of a 100% renewable energy source (RES) based system. Especially energy storage system (EES) and supplementary biopower system as well as photovoltaic (PV) and wind power component were included in the proposed RES-based system to overcome the intermittence of RESs and to efficiently balance energy supply and demand. To comparatively analyze the levelized cost of electricity (LCOE) of different RES-based systems, six scenarios were developed according to the involved RESs: PV, wind, PV/wind, PV/biopower, wind/biopower, and PV/wind/biopower systems. We then applied the proposed systems to build a 100% RES-based system in Jeju Island, Korea. As a result, the single component based system, PV and wind power system of 0.18 and 0.28 $/kWh, respectively, cannot compete with the economics of existing electricity grid. However, the optimal LCOE of the hybrid system where PV and wind power are used as main supply options and biopower as supplementary option was identified to be 0.08 $/kWh, which can compete with the economics of an existing electricity grid.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1115-1121
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• 2015

Fast inspection of solder ball bumps in ball grid array (BGA) is an important issue in the flip chip bonding technology. Particularly, semiconductor industry has required faster and more accurate inspection of micron-size solder bumps in flip chip bonding, as the density of balls increase dramatically. In this paper, we describe an inspection approach of BGA balls by using 5-step ring illumination device and normalized cross-correlation (NCC) method. The images of BGA ball by the illumination device show unique and distinguishable characteristic contours by their 3-D shapes, which are called as "iso-slope contours". Template images of reference ball samples can be produced artificially by the hybrid reflectance model and 3D data of balls. NCC values between test and template samples are very robust and reliable under well-structured condition. The 200 samples on real wafer are tested and show good practical feasibility of the proposed method.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.119-125
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• 2004

Unsteady nonlinear wave motions on the free surface over a plane beach of constant slope are numerically simulated using a finite difference method in rectangular grid system. Two-dimensional Navier-Stokes equations and the continuity equation are used for the computations. Irregular leg lengths and stars are employed near the boundaries of body and free surface to satisfy the boundary conditions. Also, the free surface which consists of markers or segments is determined every time step with the satisfaction of kinematic and dynamic free surface conditions. Moreover, marker-density method is also adopted to allow plunging jets impinging on the free surface. The second-order Stokes wave theory and solitary wave theory are employed for the generation of waves on the inflow boundary. For the simulation of wave breaking phenomena, the computations are carried out with the plane beach of constant slope in surf zone. The results are compared with each other. The marker-density method is better then the hybrid method. Also they are compared with other existing experimental results. The Agreement between the experimental data and the computation results is good.

• Industrial Engineering and Management Systems
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• v.16 no.1
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• pp.129-140
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• 2017

This research was conducted in order to solve the problem of selecting an operational strategy for projects in project-based organizations by designing a fuzzy expert system. In the current research, we first determined the contributing parameters in operational strategy of project-based organizations based on existing research literature and experts' opinion. Next, we divided them into two groups of model inputs and outputs and the rules governing them were determined by referring to research literature and educational instances. In order to integrate rules, the revised Ternary Grid (revised TG) and expert opinions were applied according to a hybrid algorithm. The Ultimate rules were provided in Fuzzy Inference System format (FIS). In this FIS, proper manufacturing decisions are recommended to the user based on selected competitive priority and also project properties. This paper is the first study in which rules and relations governing the parameters contributing operational strategy in project-based organizations are acquired in a guided integrated process and in the shape of an expert system. Using the decision support system presented in this research, managers of project-based organizations can easily become informed of proper manufacturing decisions in proportion with selected competitive priority and project properties; and also be ensured that theoretical background and past experiences are considered.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2062-2069
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• 2015

In the series hybrid active power filter (SHAPF) with magnetic flux compensation (MFC), the system current oscillate in the experimental results when adding the same phase harmonic current command in current control block. This condition endangers the security of the SHAPF. Taking the digit period average arithmetic as example, this paper explains the inter-harmonics current oscillation in the experiment. The conclusion is that the SHAPF is unstable to the inter-harmonics current in theory. Limited by the capacity of the inverter, the system current and the inverter output current do not increase to infinite. At last, some methods are proposed to solve this problem. From the practical viewpoint, the voltage feed-forward control is easy to achieve. It can suppress the current oscillation problems, and also improve the filtering effect. The feasibility of the methods is validated by both the emulation and experiment results.

• Ocean Systems Engineering
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• v.1 no.4
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• pp.317-336
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• 2011

A time domain finite element based method is employed to analyze wave radiation by multiple cylinders. The nonlinear free surface and body surface boundary conditions are satisfied based on the perturbation method up to the second order. The first- and second-order velocity potential problems at each time step are solved through a finite element method (FEM). The matrix equation of the FEM is solved through an iteration and the initial solution is obtained from the result at the previous time step. The three-dimensional (3D) mesh required is generated based on a two-dimensional (2D) hybrid mesh on a horizontal plane and its extension in the vertical direction. The hybrid mesh is generated by combining an unstructured grid away from cylinders and two structured grids near the cylinder and the artificial boundary, respectively. The fluid velocity on the free surface and the cylinder surface are calculated by using a differential method. Results for various configurations including two-cylinder and four-cylinder cases are provided to show the mutual influence due to cylinders on the first and second waves and forces.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1039-1048
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• 2011

Carrier Ethernet, which extend The algorithm based on constructing the mixed topology and performing link stretching, MT/s, has been proposed for designing cost-efficient Carrier Ethernet in optical network with multi-line-rate. However, the MT/s algorithm has high blocking ratio because the wavelength capacity is fully allocated without considering the load balance of network. In this paper, we propose an efficient mixed topology configuration (EMTC) algorithm by modifying MT/s algorithm. In order to reduce blocking ratio, we adapt a threshold for each link to restrict the link utilization so that traffic load can be distributed over whole network. We also apply the EMTC algorithm into optical hybrid switched network to evaluate the availability of our algorithm for different applications. The performance of the EMTC algorithm is compared with that of MT/s algorithm through OPNET simulation. The simulation results show that our algorithm achieve lower blocking ratio than the MT/s algorithm. Moreover, in hybrid switched network, our algorithm performs better than MT/s algorithm in terms of packet loss ratio and end-to-end delay.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.4
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• pp.328-333
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• 2014

A hybrid particle-mesh method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations is a combination of the Vortex-In-Cell(VIC) method for convection and the penalization method for diffusion. The key feature of the numerical methods is to determine velocity and vorticity fields around a solid body on a temporary grid, and then the time evolution of the flow is computed by tracing the convection of each vortex element using the Lagrangian approach. Assuming that the vorticity and velocity fields are to be computed in time domain analysis, pressure fields are estimated through a complete set of solutions at present time step. It is possible to obtain vorticity and velocity fields prior to any pressure calculation since the pressure term is eliminated in the vorticity-velocity formulation. Therefore, pressure field is explicitly treated by solving a suitable Poisson equation. In this paper, we propose a simple way to numerically implement the vorticity-velocity-pressure formulation including a penalty term. For validation of the proposed numerical scheme, we illustrate the early development of viscous flows around an impulsive started circular cylinder for Reynolds number of 9500.