• International Journal of Automotive Technology
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• v.6 no.6
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• pp.643-655
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• 2005

The frontal crash optimization of S-shaped closed-hat section member using the homogenization method, design of experiment (DOE) and response surface method (RSM) was studied. The optimization to effectively absorb more crash energy was studied to introduce the reinforcement design. The main focus of design was to decide the optimum size and thickness of reinforcement. In this study, the location of reinforcement was decided by homogenization method. Also, the effective size and thickness of reinforcements was studied by design of experiments and response surface method. The effects of various impact velocity for reinforcement design were researched. The high impact velocity reinforcement design showed to absorb the more crash energy than low velocities design. The effect of size and thickness of reinforcement was studied and the sensitivity of size and thickness was different according to base thickness of model. The optimum size and thickness of the reinforcement has shown a direct proportion to the thickness of base model. Also, the thicker the base model was, the effect of optimization using reinforcement was the bigger. The trend curve for effective size and thickness of reinforcement using response surface method was obtained. The predicted size and thickness of reinforcement by RSM were compared with results of DOE. The results of a specific dynamic mean crushing loads for the predicted design by RSM were shown the small difference with the predicted results by RSM and DOE. These trend curves can be used as a basic guideline to find the optimum reinforcement design for S-shaped member.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.183-190
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• 2014

A multiphase pump was developed in this study. The optimum multiphase pump design was arrived at, and the interactions among the different geometric configurations were explained by applying numerical analysis and the DOE (design of experiments) method. First, we designed the base model to meet the specifications. Then, we defined the design parameters related to the meridional plane and the blade angle. Each design parameter was used for generating experiment sets, and numerical analyses were performed on these sets. Finally, the optimized design was selected based on the results of the DOE analysis. The numerical optimization resulted in the optimum model having higher efficiency than the base model. In addition, performance degradation due to changes in the GVF (gas volume fraction) is discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.106-113
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• 2008

The starter motor noise is usually well identified by the customers since it is operated while the engine is quiet, and leaves distinct impressions of the vehicle. In this study the design of experiments(DOE) was applied to the identification of the noise sources of direct drive starter motor since this process usually requires lengthy analysis and elaborate experiments. In the first stage of the test, five controllable factors(alignment and dynamic unbalance of armature, tightening torques of T/bolt and center bracket bolt, and alignment of the center bracket-yoke-rear bracket), excluding static unbalance, are sorted out of all possible factors. Test results showed that the dynamic unbalance and misalignment of armature are the major factors. However, the error level of the first test was relatively high, indicating that there might be some missing major factors. In the second stage test the results showed that both static and dynamic unbalances are the dominant factors contributing to more than 80% of the overall noise, while the misalignment contributes around 12%. Error of the second test was about 4% that could be considered satisfactory. The noise level of the optimal product was predicted to be reduced by 19dBA, and verification test showed the average noise reduction of 16.8dBA with the standard deviation of 3.2dBA, and proved the usefulness of the whole DOE process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1711-1717
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• 2014

There have been many studies on IEEE 802.15.4 for home area networks(HAN) in Smart Grids. Existing unslotted or slotted IEEE 802.15.4 has almost not met strict conditions of the U.S. Department Of Energy(DOE). This study proposed a improved algorithm that reduces collisions, delay time and changes in the delay time. For this purpose, numbers were given to nodes to make the transmission in the order of the node numbers. Since the probability of the occurrence of collisions would decrease compared to random transmission if the nodes were given numbers, Backoff time was set at 0. In the proposed Numbered-Unslotted-ZeroBackoff algorithm, when the packet size was 133 octets and less than 180 packets per second occurred, it was found that packet delivery ratio was over 99.99%, and that all the maximum delay, the mean delay and the minimum delay were less than 0.02 seconds. This paper could confirm that the algorithm proposed in this study met the strict conditions of the DOE.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.50-60
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• 2019

Recently, problems with excessive vibration of the radar masts of large bulk carriers and crude oil tankers have frequently been reported. This paper explores a design method to avoid the resonance of a radar mast installed on a large ship using various design of experiment (DOE) methods. A local vibration test was performed during an actual sea trial to determine the excitation sources of the vibration related to the resonant frequency of the radar mast. DOE methods such as the orthogonal array (OA) and Latin hypercube design (LHD) methods were used to analyze the Pareto effects on the radar mast vibration. In these DOE methods, the main vibration performances such as the natural frequency and weight of the radar mast were set as responses, while the shape and thickness of the main structural members of the radar mast were set as design factors. From the DOE-based Pareto effect results, we selected the significant structural members with the greatest influence on the vibration characteristics of the radar mast. Full factorial design (FFD) was applied to verify the Pareto effect results of the OA and LHD methods. The design of the main structural members of the radar mast to avoid resonance was reviewed, and a normal mode analysis was performed for each design using the finite element method. Based on the results of this normal mode analysis, we selected a design case that could avoid the resonance from the major excitation sources. In addition, a modal test was performed on the determined design to verify the normal mode analysis results.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.333-338
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• 2021

The durability of the PEMFC stack for large commercial vehicles should be more than 5 times that for passenger vehicles. If the Chemical Accelerated Stress Test (AST) of PEMFC(Proton Exchange Membrane Fuel Cells) membrane for passenger cars is applied as it is for large commercial vehicles, there is a problem that the AST time becomes more than 2,500 hours. In order to shorten the AST time of DOE (Department of Energy), the chemical durability of the polymer membrane was evaluated using oxygen instead of air as a cathode gas. In this study, Nafion XL was used as a polymer membrane to evaluate accelerated durability under OCV, 90?, RH 30%, H₂/(air or oxygen) conditions. Among the DOE membrane durability target criteria, the decrease rate of short resistance was the fastest. By using oxygen instead of air, the degradation rate of the polymer membrane was accelerated while being less affected by electrode deterioration, reducing the polymer membrane durability evaluation time to less than half.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.840-845
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• 2004

The reliability analysis for nonnormal distributions using the three level DOE(design of experiments) method was developed by Seo and Kwak in 2002. Although this method estimates only up to the first four moments(mean, standard deviation, skewness, and kurtosis) of the system response function, the result and the type of probability distribution determined by using the Pearson system are shown very good. However the accuracy is low in case of nonlinear performance function and sometimes, the level calculated is outside of the region in which the random variable is defined. In this article we suggest a modified three level DOE method to overcome these weaknesses and to obtain optimum choice for 3 levels and weights to handle nonnormal distributions. Furthermore we extend it to finding the optimum choice for 5 levels and weights to increase the accuracy in case of nonlinear performance function. A systematic procedure for reliability analysis is then proposed by using the Pearson system.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.74-85
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• 2010

In order to formulate the compounded polypropylene(C-PP) which is suitable to an automotive door trim panel, 9 sorts of properties were measured after manufacturing the C-PP using an extruder and an injection machine with polypropylene(PP), ethylene-octene rubber(EOR) and talc. Mixture design, especially extreme vertices design, in DOE with MINITAB - commercial software was used to analyze the data. The relations between each property and each component, for example, $y=0.00907222x_1+0.00870556x_2+0.0155722x_3$ for specific gravity, were found out by the regression analysis and the variance analysis. The optimized formulation of the C-PP for an automotive door trim panel was acquired at PP(77.6962), EOR(11.0238) and talc(10.2800) by use of the response optimizer(mixture) in MINITAB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.65-71
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• 2006

This paper presents the robust design of gripper part for a high-speed LCD(Liquid Crystal Display) transfer system. In this paper, the $1^{st}$ DOE(Design of Experiment) is conducted to find out main-effect factors for the design of gripper part. Thirty-six analysis are performed using $ANSYS^{(R)}$ and their results are statistically analyzed using $MINITAB^{(R)}$, which shows that the factors, i.e., First-width, Second-width, Rec-width, and thickness of gripper part, are more important than other factors. The main effect plots shows that the maximum deflection and mass of gripper part are minimized by increasing First-width, Second-width, Rec-width and thickness. The $2^{nd}$ DOE is conducted to obtain RSM(Response Surface Method) equation. The CCD(Central Composite Design) technique with four factors is used. Optimum design is conducted using the RSM equation. Genetic algorithm is used for optimal design. Six sigma robust design is conducted to find out a guideline for control range of design parameter. To obtain six sigma level quality, the standard deviations of design parameters are shown to be controlled within 5% of average design value.