• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.57-57
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• 2007

Aspheric glass lenses have many optical advantages, for glass have superior optical performance and an aspheric form can reduce optical aberrations. Recently, the use of it is rapidly expanding as the mass production becomes possible by glass molding press and so this method is considered as the best method for fabricating an aspheric glass lens, but it is difficult to control many parameters for pressing and cooling process. Design of experiments (DOE) is a very useful tool to design and analyze complicated industrial design problems. This study investigated the pressing conditions to mold aspheric glass lenses for mega pixel phone camera module using DOE method. We have applied fractional factorial design and the response variable was set form accuracy (PV) of aspheric surface of molded lens. The results of analysis indicates that all factors expect for pressing force of each step are available for the form accuracy (PV). It was the optimum condition of the designed pressing conditions for lowering the form accuracy(PV) value of molded lens that all factors were at the low level. The form accuracy (PV) of mold and molded lens under the optimum condition are $0.85\;{\mu}m$ and $0.922\;{\mu}m$ respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1183-1188
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• 2013

The reliability of hydraulic equipment used in power plants is especially important because failures that occur in the power plant can have a great ripple effect on human lives and financial losses. In this study, specimens using the materials used in the spool and sleeve of hydraulic valves of power plants have been produced, heat-treated, and tested under the precipitation conditions of phosphate ester hydraulic fluid with a variety of conditions. 23 full factorial designs have been applied to evaluate the significance of factors that affect the wear loss of the specimen, specifically, the load, velocity, and temperature. The significance evaluation was performed on the main effects and two-way interactions for wear loss based on the experiment results, and the mathematical equations between the wear loss and the three factors were derived from the analysis results.

• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.193-200
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• 2014

Research on flow channel designs of the separate plates is necessary to improve the PEMFC performance. On concerning the performance improvement of PEMFC, many recent studies have been made on the interdigitated flow channel using forced convection. In this paper, the interdigitated flow channel is similarly applied on the parallel flow channel with a baffle or baffles. Numerical analysis is performed by using a commercial multiphysics program, which is called COMSOL, on the parallel channel with the fully blocked baffle(FBB) and there are three variables, the position of baffle, flow direction and flow velocity. Each power of the variables is resulted from the fixed 0.5V, the voltage from 80 percents of the maximum power. Finally, based on the full factorial designs(FFD), one of the design of experiments(DOE), each factor which has several levels lead to the conclusion. The analysis of the main effects and interactions of the factors is useful to find the most influenced factor to improve the power.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.685-691
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• 1998

In the first of two experiments, chemical composition (Ash, CP and CF contents), nutritive value (in vitro organic matter disappearance "lVOMD" and energy content "ME") and nitrogen retention of chopped date fronds (CDF) as affected by chemical treatment (CT) and storage duration (SD) were investigated. The experimental design was a completely randomized block, arranged in a $3{\times}4$ factorial, with 3 (CT) and 4 (SD) as the main factors using 2 replications / treatment. Three chemical treatments, were used : Control (With zero or no chemical treatment); treatment with 4% urea solution (w /w) and treatment with 4% urea + Date syrup extract (DS). The 4 (SD) were: Control (immediately after opening - without any storage or zero time storage); one month storage period; two months storage period and three months storage period. Both (CT) and (SD) had significant effects (p < 0.05) on CP and ash contents of the CDF, however there were no significant effects (p > 0.05) due to (CT) and (SD) on CF and nutritive value. High retention value (> 80%) for nitrogen was reported for the treated CDF, immediately after opening the incubated material (zero SD). However, nitrogen retention decreased with increasing (SD) to 67% after one month (SD) but tended to stay at a fairly constant level of 67% until 3 months of storage. In experiment 2, the feeding value of treated CDF was evaluated in comparison to Rhodes grass hay, using growing goats and sheep. A $4{\times}2$ factorial design was used (Four roughage sources were used : Rhodes grass hay, untreated CDF, urea-treated CDF and CDF treated with urea + DS with sheep and goats as two animal species, using three animals / treatment). Untreated CDF had a similar feeding value to Rhodes grass hay. However treatment of CDF with urea alone or with urea + DS depressed animal performance of both goats and sheep, apparently due to depression of feed intake (appetite). Feeding untreated CDF decreased feeding cost by 29% and cost/kg gain by 23%. CDF showed a good potential as a cheap local roughage and emergency feed for ruminants in the Sultanate.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.611-616
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• 2016

Computational fluid dynamic simulation based on the ABAQUS software was conducted to observe the inside flow of slot-die nozzle. The slot-die nozzle was modeled as 3-dimensional structure and three significant parameters were determined: inlet velocity of fluid, reservoir angles, number of strips none of which have been mentioned previously in the literature. The design of experiment, full factorial analysis was performed within determined design and process levels. The simulation result shows the inlet fluid velocity is most significant factor for the flows of inside nozzle. As an interaction effect, reservoir angle is closely related with number of strip that should address when the nozzle is designed. Moreover, the optimized values of each determined parameter were obtained as 35 mm/s of inlet velocity, 3 of strip numbers, and $22^{\circ}$ of reservoir angles. Based on these parameters, the outlet velocity was obtained as 0.53% of outlet uniformity which is improved from 8.67% of nominal results.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.91-99
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• 2009

Because of both precise measurement and efficient quality control, coordinate measuring machines(CMMs) have been widely used in the industry. The purpose of this paper is to present a method to estimate the CMM measurement uncertainty using design of experiments. A factorial design is applied to carry out the performance test proposed by ISO 10360 and to investigate CMM measurement errors associated to orientation and length of the length bar. In order to assess the measurement uncertainty for the performance test, an analysis of the uncertainty components that make up the uncertainty budget has been carried out. The procedure for evaluating the uncertainty of it follows GUM ("Guide to the expression of uncertainty in measurement"). The results show that the proposed method is suitable to investigate CMM performance and determine the contribution of machine variables to measurement uncertainty.

• Korean Journal of Environmental Agriculture
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• v.23 no.2
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• pp.85-91
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• 2004

The objective of this study is to determine the optimum conditions of operational parameters using factorial design for phenol degradation in photocatalytic oxidation reactors. Factorial design is widely used to select the dominant factors and their ranges in experiments involving several factors where it is necessary to study the effect of factors on a response. The effects of initial concentration of phenol, intensity of UV light and surface area of catalyst on phenol degradation were investigated. Two levels were considered in this study so that the experiment was a $2^3$ factorial design with three replicates. The experimental results show that an increase in initial concentration of phenol from 5 to 50 mg/L intensity of UV light from 5,000 to $20,000\;{\mu}W/cm^2$, and surface area of catalyst from 740 to $2,105\;cm^2$ enhanced the phenol degradation rate by an average of 1.86, 1.79, and 2.10 mg/L hr, respectively. Interaction effects do not appear to be as large on the phenol degradation rate as the main effects of single factors. The optimum working condition for photocatalytic oxidation reactors, despite the higher three factors the better removal rate, is the highest surface area or catalyst.

• Journal of Korean Institute of Industrial Engineers
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• v.8 no.1
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• pp.13-21
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• 1982

Experiments on the eye movement behavior were performed using Vidicon Eye Camera. Factorial design ( $3{\times}3$) was used to evaluate the validity of the eye movement as a performance measure in vigilance task. Eye movement data were recorded in video tapes, then the data were converted to digital signals, which were reduced to quantitative fixation and saccadic movement data by a microcomputer. To compare with existing vigilance performance measures, response time and the number of false alarms were also recorded. The results showed that the saccadic movement is a good measure of the performance in vigilance task : 1. Both the response time and the saccadic movement increased significantly during the initial two time blocks. 2. High correlations were shown between the response time and the saccadic movement. 3. The locational uncertainty affects the saccadic movement, the number of fixations, the response time but doesn't affect the duration of eye fixations.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.240-243
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• 2005

This study deals with the shape optimization of a wire spacer fuel assembly of Liquid Metal Reactors (LMRs). The Response Surface based optimization Method is used as an optimization technique with the Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer using Shear Stress Transport (SST) turbulence model as a turbulence closure. Two design variables namely, pitch to fuel rod diameter ratio and lead length to fuel rod diameter ratio are selected. The objective function is defined as a combination of the heat transfer rate and the inverse of friction loss with a weighting factor. Three level full-factorial method is used to determine the training points. In total, nine experiments have been performed numerically and the resulting datas have been analysed for optimization study. Also, a comparison has been made between the optimized surface and the reference one in this study.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.126-133
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• 2008

Linear motors are efficient mechanism that offers high speed and positioning accuracy. By eliminating mechanical transmission mechanisms such as ball screw or rack-pinion, much higher speed and greater acceleration can be achieved without backlash or excessive friction. However, an important disadvantage of linear motor system is its high power loss and heating up of motor and neighboring machine components on operation. For the application of the linear motors to precision machine tools an effective cooling method and thermal optimizing measures are required. This paper presents an investigation into the thermal behavior of linear motors with the objective of deriving the optimum cooling conditions. To reach these goals several experiments were carried out, varying operating and cooling conditions. From the experimental results, this research proposed cooling conditions to improve the thermal characteristics of the linear motors.