• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.879-886
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• 2012

The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.556-562
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• 2012

Micro electrical discharge machining (${\mu}EDM$) has been used for non-conventional material removal. One drawback of ${\mu}EDM$ is low productivity. In this study, we tried to find the optimal machining conditions to manufacture the micro hole with an optimal machining time without loss of accuracy. Taguchi method was used to figure out the relation between machining parameters and characteristics of the process. It was found that the electrode wear, the entrance and exit clearance gave a significant effect on the diameter of the micro hole when the diameter of the electrode was identical. Grey relational analysis was used to determine the optimal machining condition for minimum machining time without loss of accuracy. The obtained optimal machining condition was the input voltage of 80V, the capacitance of 680pF, the resistance of $500{\Omega}$, the feed rate of $1.5{\mu}m$/s and the spindle speed of 2900rpm. The machining time was reduced to 48% without loss of accuracy under the optimal machining condition.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.191-198
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• 2009

Some of the wargame simulators currently used in the Korean Army were developed by other countries, and do not adequately reflect the Korean Peninsula terrain and weapon systems. This implies that these war game simulators need to be calibrated with respect to the input parameters for properly assessing the effectiveness of the Korean weapon systems. In this paper, AWAM, a wargame simulator, is calibrated in terms of the time-based fighting power(FP). The FP data obtained from the Korea Combat Training Center(KCTC) are used as a reference, and the differences between the AWAM and KCTC FP data are calculated at certain points in time. Then, the Taguchi robust design method is adopted using the probabilities of hitting for the K-2 rifle as controllable input parameters. Two performance characteristics are used. One is the difference between the AWAM and KCTC FP data and the other is the score derived by grouping the difference data. For each case, optimal settings of the probabilities of hitting are determined such that the mean of each characteristic is close to 0 with its dispersion being as small as possible.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.4
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• pp.174-178
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• 2008

Nano-crystalline slaked lime was synthesized using design of experiment. In order to synthesize slaked lime, calcium chloride $(CaCl_2)$ and urea were used as starting materials. Calcium chloride solution and urea solution were mixed and heated in vessel that calcium carbonate was precipitated during heating. Precipitates were filtered, washed several times using D.I.water and ethanol and finally dried in oven. Slaked lime $(Ca(OH)_2)$ has been fabricated by the hydration of calcined $CaCO_3$. Design of experiment (Taguchi method) was used to optimize parameter, to minimize noise factors of experiment and to statistically analyze the results. Slaked lime having about 50 nm in optimized crystallite size could be obtained by calcination of $CaCO_3$ at $1000^{\circ}C$ for 0.5 h and hydration with D.I water containing ethanol and oxalic acid.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.93-97
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• 2003

Using alumina-glass infiltrated material which has been in the spotlight of biomaterials including dental material, appropriate composition of glass infiltrated material mainly depends on the thermal expansion coefficient. To obtain proper compositional glass of suitable thermal expansion coefficient effiiently. a Taguchi analysis was conducted. The influence of alkali oxide and alkali earths oxide, which affect mostly the thermal expansion coefficient of glass infiltrated material, was infiltrated material, the effect having influenced on the thermal expansion coefficient of glass was presented in this order (Na$_2$O≫K$_2$O ≫MgO≒CaO). The effect of Na$_2$O was about eight times as great as the effects of MgO, CaO and $K_2$O was about four times. Among the interaction affects of each variables the interaction affects of $K_2$O-CaO showed most significantly and thermal expansion property of specified composition was predicted by calculating contribution rate on each level of variables and interaction affects.

• Composites Research
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• v.26 no.3
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• pp.189-194
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• 2013

This paper deals with the study of mechanical properties and impact energy absorbed by composites, made by using thermoplastic and thermoset as matrix, flax fiber and nanoclay as reinforcements. The nanoclay was sprayed on the fiber laminate directly after mixing with ethanol. This experiment designed by Taguchi method and have variable factors, i.e three types of fiber direction(F), three different nanoclay wt%(N) and three spray gun hole shapes(S). According to these conditions, composites were made and the optimum conditions were found to be F1N3S1, F1N2S1, F1N2S1 and F3N2S1 for thermoplastic, and F1N3S2, F1N3S2, F1N2S2 and F3N2S1 for thermoset which were matched with tensile strength, modulus, total impact absorbed energy and heat release rate respectively.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.116-121
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• 2009

Thermosonic flip chip bonding is an important technology for the electronic packaging due to its simplicity, cost effectiveness and clean and dry process. Mechanical properties of the horn and the shank, such as the natural frequency and the amplitude, have a great effect on the bonding capability of the transverse flip chip bonding system. In this research, two kinds of study are performed. The first is the new design of the clamp and the second is the effect of tolerance parameters to the performance of the system. The clamp with a bent shape is newly designed to hold the nodal point of the flip chip. The second is the effect of the design parameters on the vibration amplitude and planarity at the end of the shank. The variation of the tolerance parameters changes the amplitude and the frequency of the vibration of the shank. They, in turn, have an effect on the quantity of the plastic deformation of the gold ball bump, which determined the quality of the flip chip bonding. The tolerance parameters that give the great effect on the amplitude of the shank are determined using Taguchi's method. Error of set-up angle, the length and diameter of horn and error of the length of the shank are determined to be the parameters that have peat effect on the amplitude of the system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1077-1083
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• 2004

This study is to systematically analyze the effect of various kinds of design factors on the performance of stratified thermal storage tank. Taguchi method, known as a very reasonable tool in the parametric study, is employed in the present work. Three dimensional unsteady numerical experiment is conducted for 4 design parameters of stratified thermal storage tank: inlet Reynolds number, Froude number, diffuser size d with 3 levels (Re=400, 800, 1200, Fr=0.5, 1.0, 2.0 and d=150 mm, 200mm, 300 mm) and diffuser shape with 2 levels. Orthogonal array $L_{18}(2{\times}3^7)$ is adopted for the analysis of variance. The result gives quantitative estimation of the various design parameters affecting the performance and helps to select the main factors for the optimum design of stratified thermal storage tank. Reynolds number is found to be the most dominant parameter and the diffuser shape plays significant role on the performance of stratified thermal storage tank. Based on this finding, the prior questions on the contribution of the diffuser shape proposed by the authors become clear. The optimum condition for the performance is a set of d=300mm, Re=800, and radial regulated plate diffuser. Conformation test shows the repeatability in the analysis and $1.3\%$ difference between the estimated thermocline thickness and that of numerical result.