• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.163-167
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• 2003

In this paper, an air-suspension type RF MEMS inductor is fabricated, and an appropriate de-embedding scheme for 3-dimenstional MEMS structure is applied and verified with inductance calculation algorithm. With the presented de-embedding method, parasitics from contanct pads and feeding lines are effectively and accurately de-embedded using open and short calibration procedure, and only spiral and posts can be characterized as a high-Q inductor structure. The validity of the de-embedding method is verified by the comparison of the measured and calculated inductances of two 1.5 and 2.5 turn square spiral inductors. The open-short de-embedded inductance error is below 5% each case in comparison with the calculated value based on H.M. Greenhouse's algorithm.

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.39-43
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• 2013

To reduce the magnetization loss of a coated conductor, the striation and the transposition have to be accomplished for magnetic decoupling. The loss reduction effect in incomplete as well as complete striated YBCO CCs was reported in previous research. At the case of the incomplete striated sample, the end region of the sample is non-striated. So, it is not jointed with each other. In power applications, the joint is needed because current leads must be connected with HTS coils. In this research, the influence of end-joint methods with copper and superconducting joint on magnetization loss in striated YBCO CC and spiral winding samples are presented and compared with non-striated measured result.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.133-137
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• 2002

In this paper, the $CF_{4}$ decomposition rate are investigated for a simulated three plasma reactors which are metal particle reactor, spiral wire reactor and reactor with porous dielectric as applied voltage. The $CF_{4}$ decomposition rate by plasma reactor with porous dielectric had a gain of 20~25[%] over that by plasma reactor with spiral wire or metal particle electrode. The $CF_{4}$ decomposition efficiency increases with increasing applied voltage up to the critical voltage for spark formation. The $CF_{4}$ decomposition efficiency of metal particle reactor was about 80[%] at AC 24[kV]. However, decomposition efficiency is more than 90% in case of the reactor with porous dielectric. we think, the reactor with porous dielectric should be much better than other reactors for $CF_{4}$ decomposition.

• Journal of The Korean Astronomical Society
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• v.25 no.1
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• pp.11-21
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• 1992

Applying mass model to disk galaxy NGC 300, since the observed rotation curve of NGC 300 is flatter than Toomre's mass model n = 1, two cases are used; obtaining parameters $a^n$ and $b^n$ from the polynomial fitting of the observed rotation curve (case A) and from the least square fitting between the observed rotation curve and model rotation curve (case B). In any case, n bas a fixed value of 1. Brandt's mass model is also discussed. which has a shape parameter n = 1.4. Calculated total mass and total mass to luminosity ratio are $3.3{\times}10^{10}M_{\odot}$, l2.1 for case A and $2.8{\times}10^{10}M_{\odot}$, 10.3 for case B. In case of Brandt's model, the values are $4.2{\times}10^{10}M_{\odot}$ and 15.4. The rise in the local mass to luminosity ratio in the outer part of NGC 300 implies existence of massive halo. Other dynamical properties are also discussed.

• Membrane Journal
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• v.27 no.1
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• pp.68-76
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• 2017

Flat membrane with $0.4{\mu}m$ pore size was prepared with PVdF (polyvinylidene fluoride) nanofiber, which has the advantages such as excellent strength, chemical resistance, non-toxicity, and incombustibility. The spiral wound module was manufactured with the flat membrane and a woven paper. Hybrid water treatment process was composed of the PVdF nanofibers spiral wound microfiltration and granular activated carbon (GAC) adsorption column. Effect of GAC packing mass was investigated by comparing the case of recycling or discharging the treated water using the synthetic solution of kaolin and humic acid. After each filtration experiment, water back-washing was performed, and recovery rate and filtration resistances were calculated. Also, effect of GAC adsorption was compared by measuring turbidity and $UV_{254}$ absorbance. As a result, there was no effect of GAC packing mass on turbidity treatment rate; however, the treatment rate of $UV_{254}$ absorbance was 0.7~3.6% for recycling the treated water, and increased to 3.2-5.7% for discharging the treated water. In the case of recycling the treated water, reversible filtration resistance ($R_r$) and irreversible filtration resistance ($R_{ir}$) trended to decrease as increasing GAC packing mass; however, total fitration resistance ($R_t$) was almost constant, and recovery rate of water back-washing trended to increase a little.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.539-546
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• 2007

In this paper, a 3-D EM simulation methodology for on-chip spiral inductor analysis has provided and it is shown that the methodology can be adapted to the highly predictable design for CMOS VCO. LC-resonator type VCO have fabricated by using standard 0.25 um CMOS process. And the LC VCO layout case which has pattern ground shielded inductors and the other layout case which has no pattern grounded inductors were fabricated for the verification of their effects on the VCO's phase noise by reducing the Q-factor of inductors. Fabricated VCO has 3.094 GHz, -12.15 dBm output at the tuning voltage of 2.5 V, and from the simulation, Q-factor of the pattern grounded inductor has increased 8% at 3 GHz, and from the measurement results, the phase noise has reduced by 9 dB at the 3 MHz off-set frequency for the pattern grounded inductor layout case.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.71-84
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• 2000

In this study, design characteristics of Village Parks in Seoul are investigated through an analysis of structuring themes expressed in spatial design. The goals and objectives of this study are: to emphasize the significance of design themes; and to demonstrate an approach to the design of landscapes through an analysis of structuring themes. For conducting this study, geometric forms and naturalistic forms were examined first. That is, the following 15 structuring themes were examined, as guiding themes: the 90$^{\circ}$rectangular theme; the 45$^{\circ}$/90$^{\circ}$angular theme; the 30$^{\circ}$/60$^{\circ}$ angular theme; circles on circle; concentric circles and radii; arcs and tangents; circle segments; the ellipse; the spiral; the meander; the free ellipse and scallops; the free spiral; the irregular polygon; the organic edge; and clustering and fragmentation. Forty five Village Parks in Seoul, built between 1996 and 1997, were analyzed through these 15 structuring themes. An analysis of Village Parks was conducted by the following two categories: land shape and structuring themes; and design directions and structuring themes. The research results are as follows; 1) Geometric forms are more frequently applied than naturalistic forms. 2) Regardless of land shape, geometric forms derived from simple primary shapes, the square and the circle, are frequently used. And the meander and the irregular polygon among naturalistic forms are frequently used. 3) Regarding design directions and structuring themes, design concepts, symbolic meanings and spatial forms are, to some degree, integrated. 4) The spiral is not applied among geometric forms. And the meander and the irregular polygon, as naturalistic forms, are frequently utilized. Research findings obtained from this study could be used in the designing of future Village Parks. For a profound study, future, research is needed in two-dimensional plans and three-dimensional elements of Village Parks.

• Solar Energy
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• v.14 no.2
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• pp.51-60
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• 1994

The fluidization characteristics of the furan foundry sand fluidized bed and the heat transfer characteristics on a single spiral coil tube in the bed have been investigated. In the paper, the heat transfer coefficients for a single spiral coil tube are measured in the furan foundry sand bed as a function of the ratio of heated coil tube pitch to diameter(p/Do) and the ratio of heated coil tube pitch to particle size(p/dp). The experimental results are as follows. 1) Mean heat transfer coefficients increases according to the increasing ratio of heated coil tube pitch to diameter(p/Do). 2) The Increasing rates of mean Nusselt numbers are more greater in the case of p/Do=1.58 than p/Do=4.75. 3) Mean Nusselt number can be expressed by the following equation, $Nu_{mean}=C\;Re^m\;Pr_g^{0.4}(p/dp)^n$.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.399-402
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• 2001

In this paper, 3-dimensional charge simulation method was applied to analyze electric field distributions of special conductor bundles equipped with spiral rods for reducing aeolian noise in a corona cage. Comparing electric field distributions of special conductor bundles in 765kV transmission tine with ones in corona case, we decide experimental voltages of special conductor bundles in corona cage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.543-550
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• 2002

In this paper, the $CF_4$ decomposition rate and by-product were investigated for two simulated plasma reactors which are metal particle reactor and spiral wire reactors as a function of mixed gases. The $CF_4$ decomposition rate by plasma reactor with metal particle electrode had a gain of 20~25% over that by plasma reactor with spiral wire electrode. The $CF_4$ decomposition efficiency increases with increasing applied voltage up to the critical voltage for spark formation. The $CF_4$ decomposition efficiency of metal particle reactor was about 80% at AC 24kV. The $CF_4$ decomposition rate used Ar-$N_2$ as base gas was the highest among three base gases of $N_2$, $Ar-N_2$, air. The by-products of the $N_2$, $N_2Ar$ base as were similar, but in case of air base they were different.