• Korean Journal of Environment and Ecology
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• v.27 no.1
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• pp.64-70
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• 2013

To examine the proportion of secondary seed dispersion by wildlife and to identify the related wildlife, We measured seed removal rates and related wildlife at the natural mixed broadleaved forest in mountain Jungwang, Pyeungchang-gun in middle part of Korean peninsula, seed-tray contained four kind of tree seeds were setted from mid-september to late-October for three years. Mean seed removal rates(MSRR) of acorn(Q. mongolica)is shown the highest values 87.2%, next MSRR of samara(A. pseudosieboldianum) does 33.1%, MSRR of samara(A. pictum subsp. mono) does 29.2%. and then SRR of samara(A. mandshuricum) does only 13.6%. Acorns are removed more faster than samaras. Among the related wildlife, Siberian chipmunks most freqently visit seed tray, and ordered Korean squirrel, Wild boar, and Yellow-throated marten. Most secondary dispersed acorns might be consumed by Wild boar, and small portions does comsumed or scatter-hoarded by rodents. Most secondary dispersed samaras might be consumed by rodents, and small portions does scatter-hoarded by rodents. A few sound seeds are remained on the forest floor in late October owing to the seed consunption and seed hoarding by wildlife. We observe seedling establishment of four broadleaved tree species. From these results, We proved Wild boar is seed comsummer, and rodents are seed consummer and seed disperser. Further studies on secondary seed dispersion, seed consumption and hoarding and related wildlife should be needed.

• Journal of electromagnetic engineering and science
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• v.4 no.3
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• pp.107-112
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• 2004

In this paper, the phase noise of 900 MHz VCO is improved using modified strip line square ring resonator. In order to demonstrate the phase noise improvement of the proposed VCO, the same circuit was manufactured using shorted-circuit resonator. In condition of the same bias current, the phase noise of the proposed VCO with modified square ring resonator is suppressed by 7 dB as - 103 dBc/Hz at 100 kHz offset compared to the conventional VCO with short-circuit resonator. From the proposed VCO, we achieved output power of - 4.8 dBm, harmonics suppression of 16 dB, and tuning bandwidth of 100 MHz. The proposed VCO consumed 5 mA at 3 V, and its size is 1.2 cm ${\times}$ 1.0 cm.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.151-151
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• 2011

Atmospheric-pressure plasmas are used in a variety of materials processes. The lifetime of most atmospheric-pressure plasma sources is limits by electrode erosion due to energetic ion bombardment. These drawbacks were solved recently by several microplasma sources based on microstrip structure, which are more efficient and less prone to perturbations than other microplasma sources. In this work, we propose microplasma sources based on strip line and microstrip line, developed for the generation of microplasmas even in atmospheric air and analyzes these systems with microwave field simulation via comparative study with two previous microwave sources (Microstrip Spit Ring Resonator (MSRR), Microstrip Structure Source (MSS)).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.60-66
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• 2007

In this paper, a novel voltage-controlled oscillator (VCO) using the microstrip square open loop multiple split ring resonator (OLMSRR) is presented for reducing the phase noise property. The square-shaped multiple split ring resonator (MSRR) having the form of the microstrip square open loop is investigated to realize this property. Compared with the microstrip square open loop resonator and the microstrip square open loop split ring resonator (OLSRR) as well as the conventional microstrip line resonator, the microstrip square OLMSRR has the larger coupling coefficient value, which makes a higher Q value, and has reduced the phase noise of VCO. The VCO with 1.7V power suppIy has the phase noise of $-124.5\;{\sim}\;-122.0\;dBc/Hz$ @ 100 kHz in the tuning range, $5.746\;{\sim}\;5.84\;GHz$. The figure of merit (FOM) of this VCO is $-203.96\;{\sim}\;-201.6\;dBc/Hz$ @ 100 kHz in the same tuning range. Compared with VCO using the conventional microstrip line resonator, VCO using the microstrip square open loop resonator and VCO using microstrip square OLSRR, the phase noise property of VCO using the proposed resonator has been improved in 25.66 dB, 8.34 dB, and 4.5 dB, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.174-179
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• 2013

This paper presents a capacitor loaded tunable bandpass chip filter using multiple split ring resonators (MSRRs) with two transmission zeros. To obtain high selectivity and minimize the chip size, asymmetric feed lines are adopted to make a pair of transmission zeros located on each side of passband. Compared with conventional filters using cross-coupling or source-load coupling techniques, the proposed filter uses only two resonators to achieve high selectivity through a pair of transmission zeros. In order to optimize selectivity and sensitivity (insertion loss) of the filter, the effect of the position of asymmetric feed line on transmission zeros and insertion loss is analyzed. The SOI-CMOS switched capacitor composed of metal-insulator-metal (MIM) capacitor and stacked-FETs is loaded at outer rings of MSRRs to tune passband frequency and handle high power signal up to +30 dBm. By turning on or off the gate of the transistors, the passband frequency can be shifted from 4GH to 5GHz. The proposed on-chip filter is implemented in 0.18-${\mu}m$ SOI CMOS technology that makes it possible to integrate high-Q passive devices and stacked-FETs. The designed filter shows miniaturized size of only $4mm{\times}2mm$ (i.e., $0.177{\lambda}g{\times}0.088{\lambda}g$), where ${\lambda}g$ denotes the guided wave length of the $50{\Omega}$ microstrip line at center frequency. The measured insertion loss (S21)is about 5.1dB and 6.9dB at 5.4GHz and 4.5GHz, respectively. The designed filter shows out-of-band rejection greater than 20dB at 500MHz offset from center frequency.