• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1997-2000
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• 2005

In this work, the effects of orthogonal ribs on warpage of plastic structure through injection molding process were investigated. Three kinds of injection molds were prepared to perform injection molding experiments of orthogonal stiffened plastic plate. The warpage of each injection molded specimen was measured using 3D CMM. And plastic injection molding analysis with commercial code was performed for the presented model. Numerical results of injection molding analysis were compared with those of experiments. It was shown that orthogonal ribs have a significant effect on the warpage of the structure in both cases of experiment and numerical analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1084-1088
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• 1995

In this paper, an electrostatic plate resonator with four corrugated bridges and another with four flat ones have been fabricated and tested by the electrostatic actuation. The resonators consist of one rigid plate and four bridges. Boron diffusion process and anisotropic etch process with EPW are mainly used to fabricate the resonators. The dynamic characteristics of the fabricated resonators are obtained by measuring the velocity of the center of the rigid plate using a laser vibrometer. The results show that the deflection of the resonator with the corrugated bridges is larger than the resonator with the flat ones. It has been confirmed that the corrugated structure releases the residual tensile stress in the bridges resulted from the diffusion process.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.201-208
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• 2013

Recently, there has been an active study about weight reduction for automotive. This study is prediction and evaluation of one pice type steering component, which is universial joint. Steering system is a core of major safe device in vehicle. Universial shaft adopted in steering system transmit steering torque between olumn and steering gear. Conventional universial shaft is produced by welding process because of geometric complexity. But welding process has some weakness such as deflection on surface, residual stress, and deteronration of material properties so it can deteriorate durability of vehicle.

• Geomechanics and Engineering
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• 제14권5호
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• pp.499-507
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• 2018

In this paper splitting failure on rock pillars among the underground caverns has been studied. The damaged structure is considered to be thin plates and then the failure mechanism of rock pillars has been studied consequently. The critical load of buckling failure of the rock plate has also been obtained. Furthermore, with a combination of the basic energy dissipation principle, generalized formulas in estimating the number of splitting cracks and in predicting the maximum deflection of thin plate have been proposed. The splitting criterion and the mechanical model proposed in this paper are finally verified with numerical calculations in FLAC 3D.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.142-145
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• 2006

A method of plane expansion of reinforced concrete apartments using precast concrete was developed. The method increased the stiffness of the precast slab using two ribs and allowed to cast concrete for multi stories. The proposed precast system is capable to construct concrete slabs without props. Ten reinforced concrete slabs were tested in order to investigate the stiffness increase of the developed precast slab with two rids. Comparison between the proposed precast slab and the slab without ribs indicated that the deflection of the precast slab was decreased by using rids.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.38-41
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• 2006

Wheel load fatigue experiment is carried out on a FRP-concrete composite deck. In FRP-concrete composite deck, FRP plays a role of a main tensile member as well as a permanent formwork and concrete plays a role of a main compressive member. Wheel load fatigue experiment, which shows more realistic behavior than pulsating fatigue experiment, is selected as a fatigue performance evaluation method. Until 1,000,000 cycles of loadings, load resistant performance is maintained without any loss, while residual deflection is increased.

• International Journal of Precision Engineering and Manufacturing
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• 제1권2호
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• pp.105-114
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• 2000

An output feedback control (OFC) is presented for a linear stochastic system with known disturbance and applied to a flexible spacecraft for the reduction of residual vibration while allowing the natural deflection during operation. By converting the tracking problem into regulator problem, the OFC minimizes the expected value of a guadratic objective function composing of error stats which always remain on the intersection of sliding hypersurfaces. For the numerical evaluation with a flexible spacecraft, a large slewing maneuver strategy is devised with a tracking model for nominal trajectory and start-cost-stop strategy for economical maneuver in conjunction with the input shaping technique. The performance and efficacy of the proposed control scheme are illustrated with the comparison of different maneuver strategies.

• 한국분말재료학회지
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• 제4권1호
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• pp.9-17
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• 1997

The mullite-zirconia composites were prepared by the pressureless sintering with addition of 10~20 vol% ZrO$_2$(TZ3Y) in the fused mullite and sol-gel mullite matrix. The densification rate of sol-gel mullite was higher than that of fused mullite, and the addition of ZrO$_2$(TZ3Y) was effective on the densification of fused mullite. The enhancement of densification and anisotropic growth of mullite in ZrO$_2$added specimen can be explained by the solid solution effect of $Zr^{+4}$ ion in mullite. Both mechanical strength and fracture toughness of mullite-zirconia composite were enhanced compared to those of mullite. The enhancement of mechanical properties is attributed to the hinderance of grain growth and the combined toughening effects of tetra-mono phase transformation and crack deflection due to the residual stress between mullite/ZrO$_2$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.721-725
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• 1996

The microfabricated test structures were used in order to evaluate the stress characteristics in films. The test structures were fabricated using surface micromachining technique, including HF vapor phase etching as an effective release method. The fabricated structures were micro strain gauge, cantilever-type vernier gauge and bridge for stress measurement, and cantilever for stress gradient measurement. The strain was measures by observing the deformation of the structures occurred after release etching and the amount of deformation can be detected by micro vernier gauge, which has gauge resolution of 0.2${\mu}{\textrm}{m}$. The detection principles and the degree of precision for the measured strain were also discussed. The characteristics of residual stress in LPCVD polysilicon films were studied using these test structures. The stress gradient due to the stress variation through the film thickness was calculated by measuring the deflection at the cantilever free end.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.196-201
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• 2002

This paper deals with the active vibration control of a simply-supported beam under a Moving mass using fuzzy control technique. Governing equation3 for dynamic responses of the beam under a moving mass are derived by Galerkin's mode summation method. Dynamic responses of the beam are obtained by Runge-Kutta integration method, and are compared with experimental results. For the active vibration control of the beam due to moving mass, a controller based on fuzzy logic was designed. The numerical predictions for dynamic deflections of the beam have a good agreement with the experimental results well. As for the fuzzy control of the tested beam, more than 50% reductions of dynamic deflection and residual vibrations under a moving mass are demonstrated.