• Journal of Society of Preventive Korean Medicine
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• v.18 no.2
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• pp.101-113
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• 2014

Objective : Ephedra Herba has been widely used for patients with common cold, asthma in eastern countries, especially china japan and korea. Recently it has been also used for obesity in clinic with high frequency. This study was designed to investigate the effects of Ephedra Herba ethyl-acetate fraction (EEAF) on hyperlipidemic mice. Method : Effects on total cholesterol, HDL-cholesterol, triglyceride, AST, ALT, fasting blood glucose in serum were measured in this experiment, and in addition, histopathological and gene expression changes in liver tissue was also observed. Results : In our study, EEAF did not affect weight gain in hyperlipidemic mice. Oral administration of EEAF lowered levels of total cholesterol which were elevated by induction of hyperlipidemia. And administration of EEAF lowered fasting blood glucose significantly. By carrying out ontological analysis, large numbers of genes were identified in up or down regulated genes. The expression of the genes that were altered in response to high-fat diet was restored to normal levels in EEAF treated mice, with a recovery rate of 49%. And it was considered that fatty acid metabolism was one of important key pathway of the recovery. Conclusion : Results in our study suggest that EEAF can prevent obese and through regulation of dyslipidemia and hyperglycaemia.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.54-62
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• 2009

The purpose of this study is to develop a piezo injector driver for common-rail direct injection diesel engines. In this research, we analyzed the electrical and mechanical characteristics of the piezo actuator through experiments. Current flow and charging voltage of the piezo injector are controlled by the PWM signal of variable duty ratio in order to realize both fast response and low peak current. The optimal switching duty ratio was designed by modeling and analyzing of the piezo driver circuit. In order to avoid resonance and unacceptably long settling time, appropriate frequency range of the PWM signal was derived based on the driver circuit model. The developed injector driver was validated by experiments under various fuel rail pressure, injection duration, and charging voltage.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.55-59
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• 1998

In practice, the property of nonlinearity is contained in all physical systems. In other word, all physical systems are nonlinear to some degree. Therefore it is important that we acquires a facility for analyzing feedback control systems with varying degrees of nonlinearity. To operate the system linearly over wide range of variation of signal amplitude and frequency, the system requires components of an extremely high quality. Such a system would probably be impractical in the view points of cost, space and weight. In this context of view, it is worth noting that the nonlinearities may be intentionally introduced into a system in order to compensate for the effects of other undesirable nonlinearities or to obtain better performance than what could be achieved using linear element only. A simple example of an intentional nonlinearity is the use of a nonlinear damped system to optimize response in accordance with the magnitude of error. In this paper, an on-off type nonlinear controller is introduced and the applicability and validity of a simple on-off controller are presented by the experimental result.

• Biomolecules & Therapeutics
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• v.5 no.2
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• pp.150-157
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• 1997

Capsaicin cream has been used to attenuate the pain associated with diabetic neuropathy, rheum-atoid arthritis, osteoarthritis and postherpetic neuralgia. But its common side effect, local irritation, limits the use of it and there is still a need for a new analgesic devoid of this side effect. This study was conducted to compare the local irritant effect of DA-5018, a new capsaicin derivative, with that of capsaicin in various animal models and human beings. Capsaicin, applied topically to the mouse ear, produced dose-dependent increase of ear volume and the frequency of ear scratching behavior in mice. Neither ear volume nor scratching behavior was affected by DA-5018. In eye wiping test of rat, DA-5018 was 10 times less irritant than capsaicin. Capsaicin administered intradermally into the rat paw elicited paw lick/lift response with a potency which was three times that of DA-5018. Zostrix-HP (0.075% capsaicin cream), but not DA-50180.3% cream, increased ear volume of rat and induced thermal hyperalgesia in normal and carrageenan inflamed paws. Six day-treatment of Zostrix-HP failed to develop tolerance against this thermal hyperalgesia. In human beings, Zostrix-HP produced burning sensation and itching in more than 90% of volunteers involved and its maximum irritant effect was significantly higher than that of DA-5018 cream. These results suggest that local irritation and burning sensation produced by DA-5018 is much less than capsaicin.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.203-212
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• 2002

Active magnetic hearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. This paper describes a design and test of an active magnetic bearing system with 16-pole radial magnets. The spindle is originally designed for a CNC lathe and driven by outer motor with 5.5 kW power and maximum speed 10,000 rpm. Considering static load condition and geometric restrictions, radial magnet is designed 16-pole type for smaller outer diameter of the spindle system. Dynamic system characteristics such as natural frequency, critical speed, stiffness, damping and system stabilities are simulated with a rigid rotor model including direct feedback controller. The designed spindle system is realized with digital PIDD controller to compensate phase lag of PWM amplifier and magnet coils. With levitation and step response experiment the control system characteristics are tested, and the spindle is rotated up to 10,000 rpm stab1y.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1074-1078
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• 2005

In precision positioning applications, such as scanning tunneling microscopy and diamond turning machines [1], it is often required that actuators have nanometer resolution in displacement, high stiffness, and fast frequency response. These requirements are met by the use of piezoceramic actuators. A major limitation of piezoceramic actuators, however, is their lack of accuracy due to hysteresis nonlinearity and drift. The maximum error due to hysteresis can be as much as 10-15% of the path covered if the actuators are run in an open-loop fashion. Hence, the accurate control of piezoceramic actuators requires a control strategy that incorporates some form of compensation for the hysteresis. One approach is to develop an accurate model of the hysteresis and the use the inverse as a compensator. The Preisach model has frequently been employed as a nonlinear model for representing the hysteresis, because it encompasses the basic features of the hysteresis phenomena in a conceptually simple and mathematically elegant way. In this paper, a new numerical inversion scheme of the Preisach model is developed with an aim of compensating hysteresis in piezoceramic actuators. The inversion scheme is implemented using the first-order reversal functions and is presented in a recursive form. The inverted model is then incorporated in an open-loop control strategy that regulates the piezoceramic actuator and compensates for hysteretic effects. Experimental results demonstrate satisfactory regulation of the position of the piezoceramic actuator to the desired trajectories.

• The Korean Journal of Applied Statistics
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• v.19 no.2
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• pp.331-338
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• 2006

Quantification method III is designed by C. Hayashi as visualizing technique for two-way cross-classified tables. Specially in Japan, its usefulness is timely proven in social and marketing surveys. In several instances, relatively large quantification scores are assigned to low-frequency categories. Thus, they lead to unreliable data interpretation. The aim of this study is to develop stable solution to overcome such traits of quantification method III. The solution is of shrinkage type induced by small perturbations and is applied to a multiple response data obtained in a Korean social survey.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.723-729
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• 1994

We have investigated on the photoreflectance(PR) of heavily Si-doped n-GaAs. The PR response was found to be dependent of modulation beam intensity, modulation frequency, and temperature. From the observed Franz-Keldysh oscillation(FKO), we determined the band gap energy and surface electric field. As the temperature is decreased from room temperature to 77K, the band gap energy increases while the surface electric field decreases. The quality of crystal was greatly increased after thermal annealing for 5 min at $500^{\circ}C$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.457-462
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• 2006

This paper is concerned with the active vibration control experiment on cylindrical shell equipped with Macro Fiber Composite(MFC) actuators. The MFC actuators were glued to the cylindrical shell in circumferential directions. To verify the theoretical result, vibration test using impact hammer and accelerometer was carried out. It was found from experiments that theoretical result predicts experimental result to some extent. The positive position feedback controllers were designed and applied to the test article. It was observed that the resonant amplitude of the fundamental mode was reduced by 20dB thus achieving active vibration control. The active vibration control of the response subject to non resonant excitation has been of interest. We developed the combination of the positive position feedback controller which can cope with the fundamental mode and the positive position feedback controller which can counteract the external disturbance with non resonant frequency. It was found from experiments that the hybrid controller can suppress the vibration amplitude successfully.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.482-484
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• 2005

The Modulation Transfer Function (MTF) is commonly used to characterize the spatial quality of imaging systems. This work is the attempt to measure the MTF at Nyquist frequency of the satellite imaging system what has 1m spatial resolution for KOMPSAT-2 image using the edge function. Artificial tarp targets are used in this study. A type of this tarp edge consists of two adjacent uniform bright and dark sides commonly used to test the performance of an optical system in edge function. The results from this work demonstrate the potential applicability of this method to estimate the response characteristics for KOMPSAT-2 that is scheduled to be launched.