• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.367-372
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• 2012

This paper presents a development of an analog type magnetic positioning system and its positioning accuracy improvement using fuzzy inference system. As the magnetic positioning system used on a magnet-gyro guidance system for AGV(automatic guided vehicle), it measures a position of magnet embedded in floor of the work place. The existing product of the magnetic positioning system is very expensive in Korea because it is being sold in a foreign country exclusively. Moreover, the positioning accuracy of the product is low because it uses digital type unipolar hall sensors. Hence, we developed the magnetic positioning system by ourselves and improved the positioning accuracy of the developed magnetic positioning system using fuzzy inference system. For experiment, we used the analog type magnetic positioning system which we have developed, and compared the performance of the proposed method with the performance of the existing positioning method for the magnetic positioning system. In experimental results, we verified that the proposed method improved the positioning accuracy of the magnetic positioning system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.245-256
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• 2003

2-D OCDMA is considered to be a viable technical solution for optical LANs, and a considerable amount of research effort has been devoted to various 2-D OCDMA techniques. In this paper, we propose two new interference model for 2-D OCDMA LANs employing unipolar random codes, and derive maximum-likelihood detectors based on these interference models. The BER performance of the maximum likelihood detectors and that of other existing detectors are compared through extensive computer simulation. In addition, the complexity of high-speed implementation of the detectors is assessed, and as a result, we found that the AND detector and the maximum-likelihood detectors for the pulse-binomial and the pulse-Poisson model offer the best trade-off between the BER performance and the facility of high-speed implementation.

• The Korean Journal of Physiology
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• v.20 no.1
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• pp.9-15
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• 1986

The effect of dopamine on the propagation and the frequency electrical activities (slow wave) of the stomach was studied in isolated stomach muscle strips of 145 cats, The gastric slow wave monopolarly recorded by four capillary electrodes (Ag-AgCl) in Krebs-Ringer solution $(ph\;7.4,\;temperature\;36{\pm}0.5^{\circ}C)$ bubbled with 5% $CO_2$ in $O_2$. Dopamine caused concentration-dependent changes of direction of slow wave propagation with decline in development of irregular propagation by domperidone pretreatment. Dopamine also increased the variation of slow wave frequency concentration-dependently. The variation of slow wave frequency induced by dopamine was significantly inhibited by pretreatment with domperidone and phentolamine but not with propranolol, hexamethonium and tetrodotoxin. It is therefore suggested that dopamine plays a role in the genesis of gastric electrical abnormality acting on dopamine receptors and partly on ${\alpha}-adrenergic$ receptors in cats.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.1
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• pp.20-25
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• 2008

Acoustic holography exhibits the spatial distribution of sound pressure in time or frequency domain. The obtained picture often contains far more than what we need in practice. For example. when we need to know only the locations and overall propagation pattern of sound sources. a method to show only what we need has to be introduced. One way of obtaining the necessary information is to use envelope in space. The spatial envelope is a spatially slowly-varying amplitude of acoustic waves which contains the information of sources' location. A spatial modulation method has been theoretically developed to get a spatial envelope. By applying the spatial envelope. not only the necessary information is obtained but also computation time is reduced during the process of holography. The spatial envelope is verified as an effective visualization scheme in time domain by being applied to complicated sound fields.

• Journal of IKEEE
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• v.25 no.3
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• pp.517-527
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• 2021

This paper presents the phase-shift full-bridge DC-DC converter using the one-chip micom. The proposed converter primary is the full-bridge power topology that operates with the unipolar pulse-width modulation (PWM) by the phase-shift method, and the secondary is the full-bridge full-wave rectifier composed of four diodes. The control of proposed converter is performed by the one-chip micom and its MOSFET switches are driven by the bootstrap circuit. Thus the total system of proposed converter is simple. The proposed converter achieves high-efficiency using the resonant circuit and blocking capacitor. In this paper, first, the power-circuit operation of proposed converter is explained according to each operation mode. And the power-circuit design method of proposed converter is shown, and the software control algorithm on the micom and the feedback and switch drive circuits operating the proposed converter are described, briefly. Then, the operation characteristics of proposed converter are validated through the experimental results of a designed and implemented prototype converter by the shown design and implementation method in this paper. The highest efficiency in the results was about 92%.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.763-770
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• 2021

In this paper, in order to exclude the influence of BAN(Body Area Network) signals operating in the ISM band, the design and optimization process of an on-body microstrip patch antenna operating at 4.567 GHz is presented. The antenna for the monitoring of the lower legs with cancellous osteoporosis is designed to be lightweight and compact with improved return loss and bandwidth. The structure around the applied lower leg consisted of a five-layer dielectric plane. Taking into account losses, the complex dielectric constant of each layer is calculated using multi Cole-Cole model parameters, whereas a unipolar model is used for normal or osteoporotic cancellous bones. The return loss of the coaxial feed antenna on the phantom is -67.26 dB at 4.567 GHz, and in the case of osteoporosis, at the same frequency the return loss difference is 35.88 dB, and the resonance frequency difference is about 7 MHz.

• Korea and Global Affairs
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• v.2 no.2
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• pp.89-130
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• 2018

This paper is to analyse the development of the U.S.-China relationship and pending issues and implications. To this end the paper is composed of 6 chapters titled instruction; the relationship between the US and China in the early and hostile confrontation period; the relationship of US-Chinese approach/normalization period and the relationship in the 1980s and 1990s; the relationship by mid-2010 since the opening of the G2 era; the US-China relations and major pending issues and implications in the era of Trump-Xi Jinping; and conclusion. The rapid growth of China over the past three decades has changed the existing US-centered international order and has triggered competition between the two countries. The United States and China have become the only countries that regularly hold strategic and economic dialogue, and the topic has also developed into a country that discusses not only bilateral relations but also global issues. The issues of US-China cooperation and conflicts encompass global issues as well as bilateral relations issues. For example, the South China Sea, the North Korean nuclear issue and the THAAD, the economic and financial order, and the Taiwan issue. It is not a matter of another country, but a problem that directly or indirectly leads to Korea's diplomacy, security and economy. In order to prevent 'Korea passing' in the US-China relationship, we need a hedging strategy that maintains and strengthens the strong ROK-US security cooperation and harmonious promotion of ROK-China economic cooperation.

• Applied Microscopy
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• v.24 no.3
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• pp.1-9
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• 1994

Pardosa astrigera possessed eight eyes arranged in three rows on the frontal carapace. A pair of small anterior lateral eyes (ALE) flanked each side by an anterior median eyes (AME) lay along the anterior margin that was situated on the anterior row of clypeus. The anterior lateral eye was composed of cornea, vitreous body, and retina. Cornea was made up mainly of exocuticle lining the cuticle. Lens in anterior lateral eye was biconvex type which bulged into the cavity of the eyecup. Outer and inner central region of lens were approximately spherical with radius of curvature $5.6{\mu}m$ and $12.5{\mu}m$, respectly. Vitreous body formed a layer between the cuticular lens and retina. They formed biconcave shape. Retina of the anterior lateral eyes was composed of three types of cells: visual cells, glia cells, and pigment cells. The visual cells were unipolar neuron, as were the receptor of the posterior lateral eye. But cell body was unique to the anterior lateral eyes. They were giant cell, relatively a few in number, and under the layer of vitreous bodies. Each visual cell healed rhabdomeres for a short stretch beneath the cell body. Rhabdomes were irregulary pattern in retina and electron dense pigment granules scattered between the rhabdomes. Glia cell situated at the cell body of visual cell and glia cell process reached to rhabdomere portion. Below the rhabdome, tapetum were about $30{\mu}m$ distance from lens, which composed of 4-5 layers. It was about $25{\mu}m$ length that intermediate segment of distal portion of visual cell. Electron dense pigment granules between the intermediate segment were observed.

• Korean Journal of Biological Psychiatry
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• v.8 no.1
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• pp.20-36
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• 2001

The debate about whether depressive disorders should be divided into categories or arrayed along a continuum has gone for decade, without resolution. In our review, there is more evidence consistent with the spectrum concept than there is with the idea that depressive disorders constitute discrete clusters marked by relatively discontinuous boundaries. First, "depression spectrum", "is there a common genetic factors in bipolar and unipolar affective disorder", "threshold model of depression" and "bipolar spectrum disorder" are reviewed. And, a new subtype of depression is so called SeCA depression that is a stressor-precipitated, cortisol-induced, serotonin-related, anxiety/aggression-driven depression. SeCA depression is discussed. But, there is with the idea that depressive disorders constitute discrete subtypes marked by relatively discontinuous boundaries. This subtypes of depressive disorder were reviewed from a variety of theoretical frames of reference. The following issues are discussed ; Dexamethasone suppression test(DST), TRH stimulation test, MHPG, Temperament Character Inventory(TCI), and heart rate variability(HRV).

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.148-158
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• 2007

Recently, IEEE 802.15.4a(low-rate UWB) technique has been paid much attention to the LR-UWB communication system for WPAN. However, there are various interferences such as MPI(Multi Path Interference) or IPI(Inter Piconet Interference) in IEEE 802.15.4a wireless channel. In order to cancel various interferences occurred to WPAN environment, in this paper, we propose a UWB wireless communication system with high QoS(Quality of Service) which is a chaotic-OOK(On-Off Keying) system using unipolar ZCD(Zero Correlation Duration) spreading code in physical layer level. Furthermore, we analyze its performance via simulations and verify the availability of proposed system with prototype implementation.