• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.370-376
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• 2011

Recently, the application range of plastic gears is widely expanding by the development of engineering plastics with good mechanical properties. Plastic gears have excellent performances such as light weight, water resistance and vibration absorbing ability for metallic gears. In this study, the optimization of injection molding process was done for the large disk type plastic gears of auto phoropter. Design Of Experiment (Taguchi method) was adopted to find a tendency of molding conditions that influence the flatness of disk type gear. Four main factors for molding conditions were selected based on injection temperature, filling time, packing pressure and mold temperature. Also, Filling, packing and cooling analyses were carried out to evaluate Z directional deflection of large disk type gear by using the simulation software (Moldflow) based on the DOE. From the results, it was found that the injection temperature and packing pressure are the most sensitive parameters for the Z directional deflection of large disk type gears.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.189-195
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• 2003

This paper represents an identification procedure for leading mechanism of a car A/V system which is composed of a DC motor and a set of plastic gears. In addition, we studied dominant noise source of rattle noise generated by external forced vibration as a car drives. we made a dynamometer to produce stationary operation on loading mechanism of A/V system because noise generated by actual loading mechanism is non-stationary signal. operating the dynamometer setup at various motor speeds, sound pressure spectra are measured and the results are analyzed. its dominant noise source is also identified by using a sound Intensity technique. we made use of multi-dimensional spectral analysis to rind a dominant rattle noise. this method is so useful to eliminate coherence between vibration sources and helps us obtain coherent output spectrum of individual vibration source which make a rattle noise.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.92-97
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• 2004

The aim of this study is to estimate the strength of injection molded plastic stepped gear. We considered stepped gear as plate model which are fixed by two edges. While, on the other sides are free. Normal gear is calculated by Lewis formula which can be derived quite simply from the equation for the stress at the root of a cantilever beam. Stress ratio(step factor) is represented for the ratio of the bending stress of normal and the bending stress of stepped gear, and it is plotted by face width factor. This study is propose the step factor added in Dupont equation which are strength estimation of step gear

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.239-245
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• 2005

Through the fatigue test of plastic gears using polyacetal polymer, this research aims at providing basic data for not only specifying operation conditions of plastic gears, but also designing dimensions of plastic gears with giving fatigue life and the estimated equation of fatigue life of plastic gears. That is, from the fatigue life curves, the estimated equation of fatigue life of plastic gears is taken out. For the estimated equation of fatigue life of plastic gears, this research provides two test methods; one is preserving non-limited temperature of tooth flank, the other is preserving limited temperature of tooth flank. As results, how the temperature of tooth flank affects the fatigue life is shown. In addition, based on the endurance limit, the essential factors of the unit load and K-factor are determined, which are needed in the design of gear by bending strength and surface durability.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.229-237
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• 2011

The pullout test is a nondestructive testing method certified by the American Society for Testing and Materials (ASTM) and British Standards (BS). Research has shown that it is very reliable in terms of evaluating the concrete strength of reinforced concrete members. However, the pullout test is rarely performed on domestic construction sites due to the complex procedures and high costs involved. This study proposes a new pullout test composed of a post installable break-off bolt, an insert nut, and a pullout tester, which satisfy both economical and practical purposes on a construction site. Three different types of special fastening methods, a temporary fixed bolt, a plastic fixed panel, and a fixed bar, have been developed. A pullout tester is proposed that is driven by the circle force introduced into a handle composed of eight gears without a load cell and a hydraulic cylinder. The serviceability and reliability of these instruments were investigated through experiments at construction sites. Furthermore, the sample pullout test with a wall specimen was conducted to estimate the usefulness of the temporary fixed bolt type of fastening methods and pullout devices. Eventually, the developed instruments will be useful on construction sites if minor requirements are met.