• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.355-359
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• 2002

Much attention has been given to EMI effects created in variable speed ac drive system. Zero switching states of inverter control invoke large common mode voltage. This paper focuses on the switching techniques to mitigate common mode voltage. This paper proposes a common-mode voltage reduction method based on sinusoidal pulse width modulation in three phase PWM inverter system. By using three carriers wave displaced by 120 degrees, it is possible to eliminate a common mode voltage pulse In one control period. Simulation and experimental results show that common mode voltages In the proposed technique are reduced more than conventional technique.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.4
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• pp.290-295
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• 2016

This paper proposes a new method for the automatic detection of atrial fibrillation (AF), using Markov regime switching GARCH (1, 1) model. The proposed method is based on the observation that variability patterns of heart rate intervals during AF significantly differ from regular patterns. The proposed method captures the different patterns of heart rate intervals between two regimes : normal and AF states. We test the proposed method using Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) atrial fibrillation database, and demonstrate the effectiveness of the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1108-1111
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• 2003

We consider geometrical conditions of liquid crystals of bent-shape molecules that result in optically isotropic antiferroelectric structure that can be reversibly switched to birefringent states. An example of an ester based banana-shape substance is discussed that almost fulfills the ideal conditions and provides fast electro-optical switching with or without crossed polarizers.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• Electrical & Electronic Materials
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• v.8 no.2
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• pp.184-189
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• 1995

The electrical property of ultra thin PVA films(several hundreds .angs.-several .mu.m in thickness) formed by sphere bulb blowing technique, has been studied. The electrical conductivity of relatively thick films(>several thousands .angs.) has been very high and enhanced by the exposure either to high humidity of air or $NH_3$, which can be explained in terms of the role of ionic transport. The use of PVA films as NH$_{3}$ sensor is also proposed. In ultra thin PVA films less than 1500.angs., two conducting states ; high conducting and low conducting states, are observed. The nonlinear current-voltage characteristics in the low conducting state and the switching between these two states are also confirmed. These properties are discussed in terms of electronic conduction processes. The breakdown strength of the ultra thin PVA film is found to be very high(-30MV/cm), supporting the electron avalanche process in a thick polymer films.

• Advances in nano research
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• v.9 no.2
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• pp.105-112
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• 2020

Silicene is a two-dimensional (2D) derivative of silicon (Si) arranged in honeycomb lattice. It is predicted to be compatible with the present fabrication technology. However, its gapless properties (neglecting the spin-orbiting effect) hinders its application as digital switching devices. Thus, a suitable band gap engineering technique is required. In the present work, the band structure and density of states of uniformly doped silicene are obtained using the nearest neighbour tight-binding (NNTB) model. The results show that uniform substitutional doping using aluminium (Al) has successfully induced band gap in silicene. The band structures of the presented model are in good agreement with published results in terms of the valence band and conduction band. The band gap values extracted from the presented models are 0.39 eV and 0.78 eV for uniformly doped silicene with Al at the doping concentration of 12.5% and 25% respectively. The results show that the engineered band gap values are within the range for electronic switching applications. The conclusions of this study envisage that the uniformly doped silicene with Al can be further explored and applied in the future nanoelectronic devices.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1199-1205
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• 1993

It has been well known that the assumption of full state availability is one of the most important restrictions to the practical realization of VSCS. And several attempts to alleviate the assumption had been made. However, it is not easy to find a positive scheme among them. Recently, an output feedback variable structure control system(OFVSCS) was proposed and the effectiveness of the scheme was validated for the disturbance free systems. The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external distrubances by extending the basic OFVSCS and to evaluate its control performances through power system stabilizer design example. The ROFVSCS is composed of dynamic switching function and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme, existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured informations, the practical application of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that the implementation cost of VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need measure the states with high measurement cost.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.458-467
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• 1994

It has been well known that the assumption of full state availability is one of the most important restrictions to the practical realization of VSCS. And several attempts to alleviate the assumption had been made. however, it is not easy to find a positive scheme among them. Recently, an output feedback variable structure control system(OFVSCS) was proposed and the effectiveness of the scheme was validated for the disturbance free systems. The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external disturbances by extending the basic OFVSCS and to evaluate its control performances. The ROFVSES is composed of dynamic switching function and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed schems, existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured informations, the practical application of VSCS for the systems with unmeasurable states and for high order systems, the conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that the implementation cast of VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need to measure the states with high measurement cost.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.433-435
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• 1993

The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external disturbances by extending the basic OFVSCS and to evaluate its control performances. The ROFVSCS is composed of dynamic switching surfaces and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme. existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured information, the practical application of VSCS for the systems with unmeasurable states and for high order systems. that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that implementation cost or VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need to measure the states with high measurement cost.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.491-499
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• 1999

This paper is on the high perfonnance propulsion IGBT VVVF inverter adopted new technique for railways. To prove the high performance and stabilit~r of traction, running tests are carried out under the simulated condition alike real field. The tests are perfonned on not only a steady states but also a transient states such a as input voltage variation using inertia load equivalent to 160tons train. The vector control technique is a adopted to improve traction for 4 motors. The low switching synchronous PW1\l method based on a space v voltage vector modulation is pro\XlSed as the optimal method for propulsion system railway. The output voltage l is controlled continuously to six step by prolxlsed ovennodu]ation technique without sudden torque variation.