• Annals of Clinical Neurophysiology
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• v.19 no.1
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• pp.3-12
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• 2017

Using threshold tracking, differences have been established between large myelinated sensory and ${\alpha}$ motor axons in humans. Major differences are that sensory axons are relatively depolarised at rest such that they have a greater persistent $Na^+$ current, and have greater activity of hyperpolarisation-activated cyclic nucleotide-gated (HCN) channels. Sensory axons may thereby be protected from hyperpolarising stresses, and are less likely to develop conduction block. However, the corollary is that sensory axons are more excitable and more likely to become ectopically active.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.557-560
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• 2006

무선 센서 네트워크를 이용한 초음파 기반 위치 인식 기술은 저비용 및 정확성을 장점으로 갖는, 잘 알려진 실내 위치 인식 기술 중 하나이다. 본 논문에서는 IEEE 802.15.4 라디오 기반의 능동적 추적 시스템에서 다중 이동 객체의 위치 인식을 지원하는 추적 시스템을 제안한다. 이를 위해 능동적 추적 시스템에서의 다중 객체 위치 인식 기술 개발상 문제점을 분석하고 이를 해결하기 위한 저비용의 Adaptive Beaconing 알고리즘을 제안한다. 또한 제안한 알고리즘을 이용한 추적 시스템을 구현한 후, 실제 건물 내부에 배포하여 실험함으로써 다중 객체 위치 추적을 위한 알고리즘의 이론적 특성을 분석하였다.

• Journal of the Optical Society of Korea
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• v.3 no.2
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• pp.80-85
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• 1999

We propose and demonstrate a new scheme for suppression of output distortion in an open-loop gyroscope employing an erbium-doped fiber amplifier/source (FAS). In addition to the main modulation for the rotation rate measurement, a small auxiliary modulation at a different frequency is used to extract an error signal, which is necessary for keeping the quasi-dc component of the feedback signal power at a constant level for varying rotation rate. By active tracking of the optimum modulation condition using this two-frequency modulation scheme, we obtain stable gyro output with suppressed distortion as well as stable FAS characteristics. We also calculate the distortion in the gyro response due to the feedback effect, from which we estimate the FAS gyro output distortion due to the residual ac feedback effect when the dc feedback effect is removed by the proposed scheme. The measured residual deviation agrees reasonably with the estimation.

• Journal of Power Electronics
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• v.13 no.1
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• pp.51-58
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• 2013

This paper proposes the power conversion mechanism of a bailer-charge-transfer zero-current-switching (CT-ZCS) circuit. The operation modes are analyzed and researched using state trajectory equations. The topology of CT-ZCS based on soft-switching inverters offers some merits such as: tracking the input reference signal dynamically, bearing load shock and short circuit, multiplying inverter N+1 redundancy parallel, coordinating power balance for easy control, and soft-switching commutation for high efficiency and large capacity. These advantages are distinctive from conventional inverter topologies and are especially demanded in AC drives: new energy generation and grid, distributed generation systems, switching power amplifier, active power filter, and reactive power compensation and so on. Prototype is manufactured and experiment results show the feasibility and dynamic voltage-tracking characteristics of the topology.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.519-525
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• 2007

With the high interest on robot technology and application, the research on artificial auditory systems for robot is very active. In this paper we discuss sound source localization and tracing based on audio-visual information. For video signals we use face detection based on skin color model. Also, binaural-based DOA is used as audio information. We integrate both informations using Kalman filter. The experimental results show that audio-visual person tracking Is useful, specially in the case that some informations are not observed.

• Journal of Power Electronics
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• v.13 no.4
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• pp.558-568
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• 2013

In this paper, a new decoupling technique for a flyback inverter using an active power decoupling circuit with auxiliary winding and a novel switching pattern is proposed. The conventional passive power decoupling method is applied to control Maximum Power Point Tracking (MPPT) efficiently by attenuating double frequency power pulsation on the photovoltaic (PV) side. In this case, decoupling capacitor for a flyback inverter is essentially required large electrolytic capacitor of milli-farads. However using the electrolytic capacitor have problems of bulky size and short life-span. Because this electrolytic capacitor is strongly concerned with the life-span of an AC module system, an active power decoupling circuit to minimize input capacitance is needed. In the proposed topology, auxiliary winding defined as a Ripple port will partially cover difference between a PV power and an AC Power. Since input capacitor and auxiliary capacitor is reduced by Ripple port, it can be replaced by a film capacitor. To perform the operation of charging/discharging decoupling capacitor $C_x$, a novel switching sequence is also proposed. The proposed topology is verified by design analysis, simulation and experimental results.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.87.2-87.2
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• 2011

Proper motion of sunspots in several active regions was studied to detect their indicator on flare onset, using data from the Solar Flare Telescope at Mitaka (four flaring active regions), TRACE (e.g. NOAA 0424, M1.7 flare on 5 Aug. 2003) and Hinode (e.g. NOAA 10930, X3.4 flare on 13 Dec. 2006). The proper motion of individual sunspots was derived using a local correlation tracking method. As a result, we found that the sunspots that are located under or close to a part of chromospheric flaring patches showed a change in their moving direction prior to the flare onset. The change in their movements took place a half to two hours before the flare onset. On the other hand, sunspots in non-flaring areas or non-flaring active regions did not show this kind of change. It is likely, therefore, that if a sunspot shows the particular movement, a chromospheric flare is to occur in its nearby region. In the most active regions, the part of flare ribbons was located on an emerging bipolar pair of sunspots. The disturbance in the usual motion of the bipolar sunspots and in other sunspots as well can be interpreted as a sign of magnetic shear development leading to final magnetic energy buildup before its sudden release. We suggest that the change in sunspot motion in a short time scale prior to the flare onset can be regarded as a good indicator in predicting the onset timing and location of chromospheric flares.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1069-1076
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• 2014

This paper presents an efficient receive beam structure able to search and track the simultaneous bundle targets with the active electrically scanned array radar. One of the characteristic with the active phased array radar is to point toward wanted direction and to forming simultaneously the digital multi-beam. This paper proposes method to detect and track rapidly bundle targets coming to radar using the digital beam forming. The proposed the beam forming method in the paper is evaluated about the angle accuracy of targets via a computer simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.6-11
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• 2010

Amount of power generated from solar photovoltaic can vary according to solar flux of sunlight due to nature of solar cell panel, and an angle that the sun and the surface of cell makes brings difference in amount of power generation. Solar flux is decided by location of surface of the Earth that is classified into longitude and latitude, but on the other hand, an angle that the sung and the surface of cell makes can be changed by changing the angle of a solar power generation device at the fixed location. A method of changing the angle of a solar power generation device as a measure for improving practical power generation efficiency. and studies about a solar tracking device for this are in active. This study conducted a research on a solar tracking system for improvement of solar power generation efficiency. A solar tracking system of this study is composed of a sensor part to confirm a location of the sun with a semiconductor photosensor using the photo conductive effect, and it analyzed output signal of a sensor by using microprocessor and it produced a control signal of driving part for tracking the sun. A solar power generator (25W) was produced to analyze performance of a solar tracking system and usefulness of a solar tracking device that was designed and produced in this study was confirmed through experiments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.830-837
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• 2015

Space debris has been a major issue recently for the space-active nations because its growing population is expected to increase the collision risk with operational satellites. Radar and electro-optical system has been used for space debris surveillance, which may cause unnecessary anti-collision manoeuvers due to their low tracking accuracy. So an additional tracking system is required to improve the predicted orbit accuracy and then to jude the anti-collision maneouvers more efficiently. The laser tracking system has been considered as an alternative to decrease these unnecessary manoeuvers. Korea Astronomy and Space Science Institute has been developing a space object laser tracking system which is capable of laser tracking for satellites with retro-reflectors and for space debris using high power laser, and satellite imaging using adaptive optics. In this study, the tracking capability is analyzed for space debris using high power laser based on link budget, false alarm probability and signal detection probability.