• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.337-343
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• 2013

In this paper, IEEE 802.11 based WLAN(5.2/5.8GHz) wideband Weathercock-shaped microstrip patch antenna was designed and manufactured. The antenna has a size of $17.4{\times}17.4mm^2$ and utilized FR-4 board. The size was minimized for mobility, and Weathercock-shaped U-slot and short-pin was inserted to satisfy adequate bandwidth and double bandwidth resonance characteristics. In addition, the antenna incorporated single both-sided patch, and simulation design optimized the Weathercock-shaped, position of the U-slot and the short-pin, and the length of the patch for the measurement. The manufactured antenna achieved a bandwidth of 695MHz from 5.2~5.8GHz zone(Return loss<-10dB). Achieved a beam width of $81.13^{\circ}$ and $85.43^{\circ}$ for 3-dB beam width of H plane and E p;ane radiation pattern, there was 3.17~4.85dBi gain.

• Journal of IKEEE
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• v.28 no.3
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• pp.279-284
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• 2024

In this paper, we propose a novel method for implementing a microstrip patch antenna with circular polarization characteristics through an asymmetric inset feed structure. The proposed method involves designing an antenna by taking advantage of the length difference of the asymmetric inset slots inserted into the antenna, as well as the lengths of additional slots incorporated into the design to achieve circular polarization characteristics. Using this approach, we designed and fabricated an antenna operating at 2.4 GHz in the S-band for satellite communication systems, utilizing a 1 mm thick FR-4 dielectric substrate. The measurement results confirmed a gain of 2dBi, an axial ratio of less than 3dB, and a reflection coefficient below -10dB in the frequency range of 2.35 to 2.43 GHz. Based on these results, it is expected that by employing the proposed method, circularly polarized antennas utilizing inset feeds can be realised, thereby making them applicable in small satellite communication systems and various wireless IoT environmental service applications that use the ISM band.

• The Korean Journal of Mycology
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• v.2 no.1
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• pp.21-24
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• 1974

Present experiments were conducted to determine the possibility of cultivation of tropical and subtropical saprophytic fungus, Volvariella volvacea (Bull. ex Fr.) Sing. under Korean climatic conditions and the-possibility of applying the method of indoor cultivation which was modified from the cultivation method of the common mushroom, Agaricus bisporus (Lange) Sing.. The results obtained were as follows: 1. In conventional outdoor cultivation, the adequate cultivation period of this fungus was from around the end of June to the end of August. 2. When rice straws submerged in water for 5 days were peak-heated for 6 days in a mush room house, the yield of the fungus was higher than that obtained from the rice straws peak-heated immediately after outdoor composting. 3. The highest yield, 20.49kg per 100kg rice straws, was obtained from the water-soaked and peak-heated rice straws which were cased with a 2 cm layer of loam at 7 days after spawning.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.232-237
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• 2024

In this paper, a broadband double dipole quasi-Yagi antenna using a 4×2 meander line array structure for maintaining 8 dBi gain was studied. The 4×2 meanderline array structure consists of a unit cell in the shape of a meanderline conductor, and it was placed above the second dipole antenna of the double dipole quasi-Yagi antenna. A double dipole quasi-Yagi antenna with generally used multiple strip directors was designed on an FR4 substrate with the same size, and the input reflection coefficient and gain characteristics were compared. Comparison results showed that the impedance frequency bandwidth increased by 6.3% compared to when using the multiple strip directors, the frequency bandwidth with a gain of 8 dBi or more increased by 10.1%, and average gain also slightly increased. The frequency band of the fabricated antenna for a voltage standing wave ratio less than 2 was 1.548-2.846 GHz(59.1%), and gain was measured to be more than 8 dBi in the 1.6-2.8 GHz band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2773-2778
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• 2015

In this paper, the compact antenna with three folded patches for use in a number of bands of LTE, WCDMA, US-PCS, and WLAN at the same time is proposed. As the changes in widths of the 3 patches to widen the insufficient bandwidth are given, it is optimized for $S_{11}$<-6dB(VSWR<3). The CPW with a number of advantages is used in the proposed antenna. The proposed antenna is designed and fabricated with FR4 substrate to the size of $44.9{\times}35{\times}1mm^3$. Fabricated antenna has within $S_{11}$<-6dB under operating bands. And measured characteristics of radiation patterns and gains are shown under operating bands.

• Journal of IKEEE
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• v.17 no.3
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• pp.275-283
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• 2013

In this paper, a 8bit 10Ms/s CMOS Folding and Interpolation analog-to-digital convertor is proposed. The architecture of the proposed ADC is based on a Folding & Interpolation using FR(Folding Rate)=8, NFB(Number of Folding Block)=4, IR(Interpolation Rate)=8. The proposed ADC adopts a preamplifier sharing method to decrease the number of preamplifier by half comparing to the conventional ones. This chip has been fabricated with a 0.35[um] CMOS technology. The effective chip area is $1.8[mm]{\times}2.11[mm]$ and it consumes 20[mA] at 3.3 power supply with 10[MHz] clock. The INL is -0.57, +0.61 [LSB] and DNL is -0.4, +0.51 [LSB]. The SFDR is 48.9[dB] and SNDR is 47.9[dB](ENOB 7.6b) when the input frequency is 100[kHz] at 10[MHz] conversion rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.218-223
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• 2010

In this paper, a novel CPW(Coplanar Waveguide)-fed UWB(Ultra Wide Band) antenna is designed, implemented, and measured for UWB communications. CPW-fed planar antenna has advantages of wide-bandwidth, low-cost and easy interaction with radio frequency front end circuitry. We have used HFSS(High Frequency Structure Simulator) of Ansoft which is based on the FEM(Finite Element Method) to simulate the proposed antenna. FR-4 substrate of thickness 1.6 mm and relative permitivity 4.4 is used for implementation. The proposed antenna showed VSWR(Voltage Standarding Wave Ratio)${\leq}2$ for the frequency band from 3.1 GHz to 10.6 GHz which is used for ultra wide band communication. Measured peak gains are 2.61, 4.95, 2.89, 7.35 dBi at 3, 6, 8, 11 GHz, respectively.

• Nuclear Engineering and Technology
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• v.39 no.3
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• pp.171-186
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• 2007

Critical issues in the development targets for the future fast reactor(FR) cycle system, including sodium-cooled FR were to ensure safety assurance, efficient utilization of resources, reduction of environmental burden, assurance of nuclear non-proliferation, and economic competitiveness. A promising design concept of sodium-cooled fast reactor JSFR is proposed aiming at fully satisfaction of the development targets for the next generation nuclear energy system. A roadmap toward JSFR commercialization is described, to be followed up in a new framework of the Fast reactor Cycle Technology development(FaCT) Project launched in 2006.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2526-2533
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• 2015

In this paper, a design method for a compact dual-band coplanar waveguide-fed slot antenna using SRR(split-ring resonator) conductor is studied. The SRR conductor is loaded inside a rectangular slot of the proposed antenna for dual-band operation. When the SRR conductor is inserted into the slot, the original rectangular slot is divided into a rectangular loop region and a rectangular slot region, and frequency bands are created by the loop and slot, separately. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 3.40-5.35 GHz band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.38-2.51 GHz and 3.32-5.38 GHz for a voltage standing wave < 2, and measured gain is 1.7 dBi at 2.45 GHz, and it ranges 2.4-3.2 dBi in the second band.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.1-7
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• 2021

In this paper, by embedding a bare-die chip-type drive amplifier into the PCB composed of ABF and FR-4, it implements an embedded active device that can be applied in 28 GHz band modules. The ABF has a dielectric constant of 3.2 and a dielectric loss of 0.016. The FR-4 where the drive amplifier is embedded has a dielectric constant of 3.5 and a dielectric loss of 0.02. The proposed embedded module is processed into two structures, and S-parameter properties are confirmed with measurements. The two process structures are an embedding structure of face-up and an embedding structure of face-down. The fabricated module is measured on a designed test board using Taconic's TLY-5A(dielectric constant : 2.17, dielectric loss : 0.0002). The PCB which embedded into the face-down expected better gain performance due to shorter interconnection-line from the RF pad of the Bear-die chip to the pattern of formed layer. But it is verified that the ground at the bottom of the bear-die chip is grounded Through via, resulting in an oscillation. On the other hand, the face-up structure has a stable gain characteristic of more than 10 dB from 25 GHz to 30 GHz, with a gain of 12.32 dB at the center frequency of 28 GHz. The output characteristics of module embedded into the face-up structure are measured using signal generator and spectrum analyzer. When the input power (P_in) of the signal generator was applied from -10 dBm to 20 dBm, the gain compression point (P_1dB) of the embedded module was 20.38 dB. Ultimately, the bare-die chip used in this paper was verified through measurement that the oscillation is improved according to the grounding methods when embedding in a PCB. Thus, the module embedded into the face-up structure will be able to be properly used for communication modules in millimeter wave bands.