• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.227-233
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• 2002

Suspension system is one of the most important components indespensible for stability and reliability of automobiles. The demands to more safe and durable suspension system have been increased as the automobiles get popular and improve in quality. The crack in the coil spring of the suspension system produced during manufacturing may grow under a fatigue load and cause a severe safety problems which lead to a catastrophic damage to the passengers. Many conventional NDT techniques including ET, RT, and UT are less sensitive or hard to apply to detect the surface breaking crack in the suspension coils partly because the techniques are point-to-point measurement methods, thus take too long time to inspect the coil spring longer than 1m. Contrary to this, Lamb wave technique is full-field measurement method that make it possible to examine the whole coil spring in real time. In this paper, the Lamb wave is applied to the coil spring to investigate the possibility to detect the cracks on the surface of the coil spring.

• Journal of KSNVE
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• v.3 no.1
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• pp.65-75
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• 1993

In this study, we identify the structural dynamic characteristics of the rigid body suspension system of waching machine containing rotating system, and consider the methods for the reduction of noise and vibration due to the structural problems. The structural dynamic characteristics of the suspension system have been studied by the computer simulation, in which the commercial software package, "DYMES(Dynamics of Mechanical System)" is used. The behaviour of the supporter by the rotating system has been parametrically studied by computer simulation, and the force and torque which are transferred to the fixed body through the suspension bar also has been calculated. The possibility to decide the position and the stability of the rigid body suspension system for waching machine is demonstrated based on various simulation results.n results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.950-955
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• 2004

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass plate handling devices that can manipulate a glass plate without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass plates is proposed. This device can directly drive a glass plate and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic forces on the glass plate and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass plates is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass plate has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.76-85
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• 2006

In the manufacture of liquid crystal display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic transportation device for glass panels is proposed. This device can directly drive a glass panel and simultaneously provide contactless suspension by electrostatic forces. To accomplish these two functions, a feedback control strategy and the operational principle of an electrostatic induction motor are utilized. The stator possesses electrodes which exert electrostatic farces on the glass panel and are divided into a part responsible for suspension and one for transportation. To accomplish dynamic stability and a relatively fast suspension initiation time, the structure of the electrode for suspension possesses many boundaries over which potential differences are formed. In this paper, an electrode pattern suitable for the suspension of glass panels is described, followed by the structure of the transportation device and its operational principle. Experimental results show that the glass panel has been transported with a speed of approximately 25.6 mm/s while being suspended stably at a gap length of 0.3 mm.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.241-256
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• 2010

This study intends to develop an aerodynamic girder for suspension bridge with width corresponding to 1/70 of the main span length. In the first step of present study, parametric study for the effects of major structural properties on aerodynamic stability of bridges was performed. The span length and natural frequency of bridges were found to be free from girder width, girder height, and aspect ratio of width to height. The empirical equation according to confidence interval was proposed to estimate the natural frequencies of bridges from span length. From the sensitivity analysis, it was revealed that the torsional frequency was dominant parameter among various structural properties that affected flutter velocity mostly. The final aerodynamic bridge section which satisfied the flutter criteria was found from section wind tunnel tests for 30 cross sectional models. The aerodynamic stability of the developed cross section was verified by multimode flutter analysis. The present economical cross section can be used for long span suspension bridge.

• YAKHAK HOEJI
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• v.56 no.2
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• pp.74-79
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• 2012

Citrate-capped silver nanoparticles (AgNPs) are widely used in industry, consumer products and medical appliances. However, information on the toxicity, environmental fate and toxicokinetics are not enough. In this study, stability of citrate-capped AgNPs was investigated using different types of isotonic solution, which is important in the toxicokinetic study by the exposure route of intravenous injection. Size, morphology, zeta potential and ion formation were investigated in isotonic solutions for the physico-chemical characterization of AgNPs. Aggregation and precipitation of AgNPs were observed in saline or phosphate-buffered saline while they were stable without precipitation in 2% glycerol of isotonic solution. The average size of AgNPs in 2% glycerol was 6~10 nm, which was almost same as that in water-based suspension of AgNPs. Zeta potential was ranged from -30 mV to -60 mV, which was in the range of original stock AgNPs. The stability was maintained during the whole experimental period of 48 hours. Furthermore, the stability was not changed in different temperature (10~36$^{\circ}C$) and at different concentrations (10~1,000 ppm). The osmolarity of the AgNPs suspension was $299{\pm}1$ mOsm/kg which was in isotonic range. These data suggest that AgNPs in 2% glycerol solution can be used for the preparations of intravenous injection for toxicokinetic study without undesired disturbance of blood isotonicity.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.5
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• pp.257-263
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• 2022

Active stabilizers use signals such as steering angle, yaw rate, and lateral acceleration to vary the roll stiffness of the front and rear suspension depending on the vehicle's driving conditions, and are attracting attention as RSC (Roll Stability Control) system that suppresses roll when turning and improves ride comfort when going straight. Various studies have been conducted in relation to active stabilizer bars and RSC systems. However, accurate modeling of passive stabilizer model and active stabilizer model and vehicle dynamics analysis result verification are insufficient, and performance result analysis related to vehicle roll angle estimation and electric motor control is insufficient. Therefore, in this study, an accurate vehicle dynamics model was constructed by measuring the passive/active stabilizer bar model and component parameters. Based on this, the analysis result with high reliability was derived by comparing the roll angle estimation algorithm based on the lateral acceleration and suspension of the vehicle with the actual vehicle driving test result. In addition, it was intended to accurately analyze the motor torque characteristics and roll reduction effects of the electric motor-driven RSC system.

• Wind and Structures
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• v.12 no.5
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• pp.475-478
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• 2009

• Wind and Structures
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• v.11 no.4
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• pp.341-344
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• 2008

• Polymer(Korea)
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• v.32 no.3
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• pp.246-250
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• 2008

Colloidal stability of the biodegradable nanoparticle was characterized by measuring the variation of particle size with time using photon correlation spectroscopy. Three kinds of polymers, namely, poly(D,L-lactide-co-glycolide)(PLGA), PLGA/poly(L-lactide) blends, and PLGA/poly(L-lactide)-g-poly(ethylene glycol) blends were used as matrix material for nanoparticle preparation. Nanoparticles were prepared with or without using poly(vinyl alcohol)(PVA) as suspension stabilizer to evaluate the condition of preparation. Nanoparticles from the blend of amphiphilic graft copolymer with short poly(ethylene glycol) chain and PLGA maintained suspension for 1 day when protein stock solution was introduced. This is somewhat improvement in colloidal stability against protein adsorption compared with that of nanoparticles without PEG moiety. Suspension stabilizer, PVA, had a significant effect on the colloidal stability against freezing and protein adsorption which led to coagulation of nanoparticles. It is important to consider effect of suspension stabilizer as well as materials used to prepare nanoparticle on the colloidal stability.