• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.370-376
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• 2012

The CSS(Chirp Spread Spectrum) technology is used for developing various WPAN(Wireless Personal Area Network) application fields in general, and it can be adapted to implement localization systems especially using SDS-TWR(Symmetric Double Sided - Two Way Ranging). But the ranging errors are occurred in many practical applications due to some interferences by some experiments. Thus, the compensation algorithm for localization is required for developing localization applications. The suggested compensation algorithm that is named KF_EDR(Kalman Filter and Equivalent Distance Rate) for localization in order to reduce the ranging errors is suggested in this paper. The KF_EDR compensation algorithm for localization is mainly composed of the AEDR(Algorithm of Equivalent Distance Rate) and the Kalman Filter. It is confirmed that the improved error ratio of the KF_EDR are 10.5% and 4.2% compared with the AEDR algorithm in lobby and stadium. From the results, it is analyzed that the KF_EDR can be widely used for some localization system in ubiquitous society.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.196-203
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• 2006

An air-gap type FBAR was designed using Leach equivalent model for analyzing a vertical structure of the FBAR. For the top electrode, Pt, and the bottom electrode, Au, of $1.2{\mu}m$ thickness and the piezoelectric of 0.8,urn thickness, the resonance and anti-resonance occurred at 2.401 GHz and 2.460 GHz, respectively. $S_{11}$ was increased and $S_{21}$ was decreased as the resonance area of FBAR was widened. We observed the characteristics of insertion loss, bandwidth and out-of-band rejection of ladder-type FBAR BPF by changing resonance areas of series and shunt resonators and by adding stages. As the resonance area of series resonator was increased, insertion loss was improved but out-of-band rejection was degraded. And as the resonance area of shunt resonator was increased, insertion loss was degraded a little but out-of-band rejection was improved even without adding stages. We, also, changed the shape of the resonance area from square shape to rectangle shape to examine the effects of the resonator shape on the characteristics of the BPF. The best performances were observed when the sizes of series and shunt resonator are $150{\mu}m{\times}l50{\mu}m\;and\;5{\mu}m{\times}50{\mu}m$, respectively. Out-of-band rejection was improved about 10dB and bandwidth was broadened from 30MHz to 100MHz utilizing inductor tuning on $2{\times}2\;and\; 4{\times}2$ ladder-type BPFs.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.4
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• pp.397-402
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• 2003

This paper concerns a pulse-width-modulation (PWM) controller design technique using digital redesign. Digital redesign is to convert a well-designed analog controller into an equivalent pulse-amplitude-modulation (PAM) controller maintaining the original analog control system in the sense of state-matching. In similar line of conversion concept, the redesigned PAM controller is converted into a PWM controller using the equivalent area principle. To convincingly visualize the proposed technique, an computer simulation example-attitude control of artificial satellite system is included.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.6
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• pp.726-731
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• 2004

This paper proposes a pulse-width-modulation (PWM) controller design technique using intelligent digital redesign. Intelligent digital redesign is to convert a well-designed analog fuzzy-model-based controller into an equivalent pulse-amplitude-modulation (PAM) digital controller maintaining the original analog control system in the sense of state-matching. In similar line of conversion concept, the redesigned PAM intelligent digital controller is converted into a PWM controller using the equivalent area principle. To convincingly visualize the proposed technique, an computer simulation example-attitude control of nonlinear artificial satellite system is included.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.5
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• pp.103-110
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• 2003

The grounding system is necessary to provide means to dissipate electric currents into the earth without exceeding any operating and equipment limits. The ground is composed of various soils and the resistivity of the soil depends on many parameters. It depends on the type of soil and varies with distance as well as with depth. Especially, soil resistivity of volcanic area such as Jeju is ve교 high and it is difficult to acquire necessary grounding resistivity. This paper introduces the efficient grounding construction using coring technique for proper grounding resistance in high resistivity area. Because it is difficult to measure the accurate resistivity of soils, their resistivities are estimated using measured value of ground resistance and equivalent radius method. Estimated resistivities are used for grounding resistance in scheduled construction region.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.807-812
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• 1997

For an equivalent uniform soil model to multiple-layered soil structure, ground depth, which is used in the calculation of equivalent resistivity, should be varied according to the size of grounding area. In case of 150 kV substation grounding design, 15 m of ground depth has been used and 25 m for 345 kV, But applying these ground depths can lead to errors in grounding resistance calculation, and these errors are coming from the poor representation of those depths to real soil resistivities. In this paper, the soil resistivity measurement techniques by Wenner method and grounding resistance calculation results by computer simulation were presented. Case studies contain the area from 3,000 to $30,000\;m^2$ and measuring space from of m to $100{\sim}250\;m$, Based of the computation results, 50 m, 60 m and 80 m of ground depth for less than 30, 40 and 70 m of equivalent hemispherical radius were proposed respectively.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.10 no.1
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• pp.1-11
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• 1981

In this paper, a new performance equation of bath tubs has been derived, which is very characteristically illuminating and in good agreement with experiments : $$T=T_{\infty}+(T_0-T_{\infty})e-\frac{k(A'_f+A_0)}{Mc_{P{\Delta}x}t$$, where $T_{\infty}$ is the temperature of the bathroom, $T_0$ that of the bathwater at t=0, k the overall heat conductivity of the tub- wall, $A'_f$ the equivalent surface area to the wall, $A_0$ the submerged area of the tub-wall, M mass of the bath-water, $C_p$ the specific heat of the bathwater and ${\Delta}x$ the thickness of the tub-wall. Here the equivalent-free surface area is written as $$A'_f=mA_f,\;m=const.(1-{\phi})^{0.88}$$ : where m is a numerical factor which is determined by a simple experiment and some calculation, {\phi}$ the relative humidity and $A_f$ the real free-surface area. From this study, it has been clarified that cooling of bath-water is mainly due to mass-transfer through evaporation from the free surface and conductive heat loss through the tub-wall is minor, which rather gaily mock at common sense. The effect of keeping bathwater warn by increase of the tub-wall thickness is also analyzed by a new idea of the thickness gain factor.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.600-606
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• 2007

3D finite element analyses of a corrugated steel web girder and a steel truss web girder are conducted to investigate the static and dynamic behaviour of the hybrid girders. And the analyses results are compared with those by the equivalent beam theory. The equivalent theory is a theory that all section properties of a truss structure are replaced by section properties of a beam including a shear coefficient. When applying the equivalent beam theory, the shear coefficient of the corrugated steel web girder is estimated as the area ratio of flange section to web section and that of the steel truss web girder is calculated by the equation proposed by Abdel. Static deflections and natural frequencies by 3D finite element analyses and those by the equivalent beam theory are in good agreement.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.348-353
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• 2010

The scattered light of solar radiance near the infrared ray area was observed to measure $H_2O$ and $O_2$ absorption lines. The changes of $H_2O$ and $O_2$ equivalent width were calculated on the basis of the measurement. $O_2$ equivalent width showed negative correlation with the amount of solar radiance; $O_2$ equivalent width had a tendency to diminish as the amount of the solar radiance increased and to increase as the amount of the solar radiance decreased. On the other hand, $H_2O$ equivalent width showed the positive correlation with the amount of solar radiance. Especially it was noted that the sum of equivalent width of absorption lines created by $H_2O$ and $O_2$ in a day was fairly constant. It is implied that the constant equivalent width is caused by the complementary development of photodissociation and recombination in $O_2$ and $H_2O$.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1897-1900
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• 2004

In recent years, a lot of industrial equipments have serial communication channel such as FieldBus (CAN, Profibus, etc.) or Ethernet that provides real time communication between industrial equipments. Theses applications include gantry crane, robot, chip mounter, etc.. In this paper, we discuss the synchronization technique for networked multi-motor systems where controllers (commercial servo amps) are distributed and interconnected by CAN (Controller Area Networks). We first describe the equivalent model for the individual servo-amp and motor using the frequency response. We design the $H{\infty}$ controller for motion synchronization. Finally, the synchronization technique using the equivalent model and the $H{\infty}$ controller is verified by the simulation and the experiment.