• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2863-2866
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• 2003

In nonlinear control fields, for irregular nonlinear systems, control form which consists of approximate tracking control law and exact tracking control law and which switches between two laws has been proposed recently. In this thesis, we design new switching control law which connect approximate linearization control law and exact linearization control law by fuzzy rules for irregular nonlinear system, ball and beam system. Fuzzy switching controller designed by fuzzy concept is proved that designed scheme overcomes singularities of irregular system, improves unstability problem of switching procedure, and has more efficient control value through simulation. Stability of fuzzy control system proved by Lyapunov's stability theorems.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.4
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• pp.7-11
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• 2013

As thermosonic ball bonding is developed for more and more advanced applications in the electronic packaging industry, the control of process stresses induced on the integrated circuits becomes more important. If Cu bonding wire is used instead of Au wire, larger ultrasonic levels are common during bonding. For advanced microchips the use of Cu based wire is risky because the ultrasonic stresses can cause chip damage. This risk needs to be managed by e.g. the use of ultrasound during the impact stage of the ball on the pad ("pre-bleed") as it can reduce the strain hardening effect, which leads to a softer deformed ball that can be bonded with less ultrasound. To find the best profiles of ultrasound during impact, a numerical model is reported for ultrasonic bonding with capillary dynamics combined with a geometrical model describing ball deformation based on volume conservation and stress balance. This leads to an efficient procedure of ball bond modelling bypassing plasticity and contact pairs. The ultrasonic force and average stress at the bond zone are extracted from the numerical experiments for a $50{\mu}m$ diameter free air ball deformed by a capillary with a hole diameter of $35{\mu}m$ at the tip, a chamfer diameter of $51{\mu}m$, a chamfer angle of $90^{\circ}$, and a face angle of $1^{\circ}$. An upper limit of the ultrasonic amplitude during impact is derived below which the ultrasonic shear stress at the interface is not higher than 120 MPa, which can be recommended for low stress bonding.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.97-103
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• 2013

This study proposes a path generation technique for simultaneous five-axis driving for ball bar measurement, which is equivalent to cone frustum machining as mentioned in the NAS979 standard. The technique is generalized for a 3D circular path, and it is applicable to all machine tools regardless of their structural configurations. A mathematical machine input model that consists of a five-axis machine tool, ball-bar measurement and conical path information as inputs is presented for easy NC code generation, simulation for various test conditions, and a measurement test. The movement range of rotary axes, which depends on various conditions, is mathematically analyzed based on the proposed conical path model. Moreover, the effect of the movement range on various conditions (apex angle and inclination angle, ball bar tilting acceptance angle, offset position of workpiece ball, etc.) is analyzed.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.1
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• pp.33-39
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• 2023

Background: Most Pilates programs for older adults have been based on mat Pilates, and there has been limited research on Pilates with mini-balls. Therefore, this study aims to compare the effects of Pilates with mini-balls and mat Pilates interventions on strength, total body endurance, flexibility, and dynamic equilibrium to determine the differences. Methods: The elderly aged 65 or older living in Gyeongsan, Daegu, were divided into two groups, and the experimental group (n=10) conducted a Pilates exercise program using mini balls for 12 weeks, and the control group (n=10) conducted a mat Pilates exercise program for 12 weeks without mini balls. Strength, endurance, flexibility, and dynamic equlibrium were measured as a pre-test, and post-test was performed in the same way after 12 weeks of application. Results: Comparing the mini-ball Pilates group to the mat Pilates group, there was a significant difference (p<.05) in the 'chair sit and reach' after the intervention. In the within-group comparison, there was a significant increase (p<.05) in 'arm curl right', '30-second chair stand', '2-minute walk', 'back scratch', 'chair sit and reach', and '2.44m up and go' in the experimental group using the mini-ball Pilates program. Mat Pilates program significantly increased the within-group comparisons in '30-second chair stand' and 'chair sit and reach' (p<.05). Conclusion: It is suggested that mini-ball Pilates has a positive effect on the senior fitness and will be a good exercise method for using it as an exercise program for the elderly in the future.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.67-72
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• 2010

In this paper, a design optimization of ball grid array packaging geometry is studied based on the Taguchi method, which allowed robust design by considering the variance of the input parameters during the optimization process. Molding compound and substrate were modeled as viscoelastic, and finite element analyses were performed to calculate the strain energy densities of the eutectic solder balls. Six quality factors of the dimensions of the packaging geometry were chosen as control factors. After performing noise experiments to determine the dominant factors, main experiments were conducted to find the optimum packaging geometry. Then the strain energy densities between the original and optimized geometries were compared. It was found that the effects of the packaging geometry on the solder ball reliability were significant, and more than 40% of the strain energy density was reduced by the geometry optimization.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.309-313
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• 2002

This paper presents an artificial intelligent model for a soccer robot. We classified soccer robot as artificial intelligent model into three elemental groups including instinct intuition and reason. Instinct is responsible for keeping the ball, walking or rushing toward the ball. This is very simple fundamental action without regard to associates and enemies. Intuition contributes to the faster/slower moving and simple basic turning to get near to the ball and to make a goal noticing associates and enemies. Reason is the most intelligent part, the law of reason is not simple relatively with instinct and intuition. We shall expect to design the best law of reason for a soccer robot some time. We also compared nerve system and muscles of human being model with controller and motors of a physical soccer robot model individually. We had designed several algorithms and made programs to investigate effects and control soccer robot.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.636-640
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• 2006

In this study, metrics for evaluation of heavy-weight impact noise were investigated. Heavy-weight impact noises generated by impact ball were recorded in real apartments using binaural microphone. Those sounds were classified into three groups according to frequency characteristics in order to control aspects which affect subjective responses to heavy-weight impact noise. Sound sources for auditory experiment were selected based on the classification result. Then auditory experiments were conducted to investigate the relationship between level indices and subjective responses. The results showed that $L_{Aeq},\;L_{Amax}$ and $LL_z$ as well as $L_{iFmax,AW}$ were highly correlated with subjective response. Therefore, $L_{Aeq}$ and $L_{Amax}$ can be used as metrics for evaluation of heavy-weight impact noise. In further studies, it is needed to verify classification of heavy-weight impact noise generated by bang machine and impact ball.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.631-635
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• 2006

In this study, simplified methods on measurement and evaluation of heavy-wight impact sound was proposed due to provide easy quality control method to construction engineers. The simplified methods include using of rubber impact ball instead of bang machine, reduced number of measuring and impact positions which is prescribed as over 4 points, using of hand-held sound level meter as a frequency analyser and prediction equation for $L_{i.Fmax.AW}$, single number rating, using $L_{Amax}$, and $L_{Lmax}$ at each frequency band. The results showed that a method of boundary driving and boundary measuring is the most similar to the current rating method.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.74-79
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• 2006

In this study, the tempering effect on the wear characteristics of induction-hardened SPS5 steel was investigated. For this purpose, three tempering conditions were applied to control the hardness of heat-treated SPS5 steel. Ball-on-disk wear tests have been performed using zircornia balls on the tempered specimens to determine the variation of wear characteristics. The results showed that friction coefficient decreased with increasing hardness for induction hardening conditions. This seems to occur because real contact area between specimen and mating ball was affected by the specimen hardness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.975-978
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• 2003

This paper presents an artificial intelligent model for a soccer robot. We classified soccer robot as artificial intelligent model into three elemental groups as instinct, intuition, reason. Instinct is responsible for keeping the ball, driving or rushing toward the ball. This is very simple fundamental action without regard to associates and enemies. Intuition contributes to the fast/slow moving and simple basic turing to get near to the ball and to make a goal noticing associates and enemies. Reason is the most intelligent part. The law of reason is not simple relatively with instinct and intuition. We also compared nerve system and muscles of human being model with controller and motor of physical soccer robot model individually. We had designed several algorithms and made programs th investigate effects and control soccer robot.