• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2058-2060
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• 2004

In this paper, circular polarized antennas of Tx 30GHz and Rx 20GHz are implemented in LTCC process. Tx antenna has a circular patch structure and Rx antenna has a ring patch structure. The feeding line of Tx antenna is placed in the center hole of Rx ring patch antenna which is printed under Tx circular patch antenna layer. It makes antenna size smaller. Tx antenna's return loss in under -10dB level from 30GHz to 31GHz and Rx antenna is under -10 dB from 20GHz to 21GHz. The isolation between two antennas is less than -20dB. Axial ratio is less than 3dB though out each band.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.202-207
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• 2017

This paper presents the performance of a planar, low-profile, and wide-gain-bandwidth leaky-wave slit antenna in different thickness values of high-permittivity gallium arsenide substrates at terahertz frequencies. The proposed antenna designs consisted of a periodic array of $5{\times}5$ metallic square patches and a planar feeding structure. The patch array was printed on the top side of the substrate, and the feeding structure, which is an open-ended leaky-wave slot line, was etched on the bottom side of the substrate. The antenna performed as a Fabry-Perot cavity antenna at high thickness levels ($H=160{\mu}m$ and $H=80{\mu}m$), thus exhibiting high gain but a narrow gain bandwidth. At low thickness levels ($H=40{\mu}m$ and $H=20{\mu}m$), it performed as a metasurface antenna and showed wide-gain-bandwidth characteristics with a low gain value. Aside from the advantage of achieving useful characteristics for different antennas by just changing the substrate thickness, the proposed antenna design exhibited a low profile, easy integration into circuit boards, and excellent low-cost mass production suitability.

• Journal of Magnetics
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• v.14 no.2
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• pp.75-79
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• 2009

Nickel (Ni) and ferrite ($Fe_3O_4$, $NiFe_2O_4$) nanoparticles were synthesized by LGC using both wire feeding (WF) and micron powder feeding (MPF) systems. Phase evolution and magnetic properties were then investigated. The Ni nanopowder included magnetic-ordered phases. The LGC synthesis yielded spherical particles with large coercivity while the abnormal initial magnetization curve for Ni indicated a non-collinear magnetic structure between the core and surface layer of the particles. Since the XRD pattern cannot actually distinguish between magnetite ($Fe_3O_4$) and maghemite (${\gamma}-Fe_2O_3$) as they have a spinel type structure, the phase of the iron oxide in the samples was unveiled by $M{\ddot{o}}ssbauer$ spectroscopy. The synthesized Ni-ferrite consisted of single domain particles, including an unusual ionic state. The synthesized nanopowder bore an active surface due to the defects that affected abnormal magnetic properties.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.63-70
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• 2012

This paper discussed on the directive gain improvement method of the U-type ultra wide-band(UWB) planar patch antenna model with CPW feeding. For directive gain improvement, the U-type printed patch antenna model with CPW feeding is reconstructed as a microstrip structure by adding a reflection plane with aperture slot. The reflection coefficient of the reconstructed antenna is less than -6.5 dB(VSWR < 3.3) to the characteristic impedance of $50.08{\Omega}$ and showed the directive radiation patterns with the directive gain of 7.5 dBi ~ 10.1 dBi, the front-back ratio of 17.8 dB ~ 28.7 dB and the range of -3dB radiation angle over ${\pm}30^{\circ}$ to the main beam direction of ${\theta}=0^{\circ}$.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.131-137
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• 2006

Most South Korean lakes are middle/small size artificial reservoirs, which are almost agricultural reservoirs (17,956). A total of 67 species (21 families) were recorded and collected from 65 agricultural reservoirs though field samplings and literature surveys. Dominant species was Pseudorasbora parva (relative abundance 24.5%), and Carassius auratur (41 sites) was the highest frequency. Feeding group of fish communities in the reservoirs was as follows: carnivorous (16.2%), omnivorous (79.5%) and herbivorous fish (4.3%). The number of individuals (P=0.024), species number (P=0.047) and carnivores number (P=0.024) were significantly correlated with reservoir ages. Reservoirs were classified into 3 groups according to feeding patterns of carnivore, omnivore and herbivore groups. The omnivores were dominant group in agricultural reservoirs. Detailed studies on fish community will be a base for the understanding of food web structure and biomanipulation in reservoir systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1221-1228
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• 2016

In this paper, we propose a modified rhombus slot UWB(Ultra Wide Band) antenna with fork-shaped feeding structure. The proposed antenna is modified rhombus slot structure and fork-shaped feeding structure to get ultra-wideband characteristics for UWB communication. Modified rhombus slot structure consists of slot shaped which eliminated upper and lower part of the basic rhombus slot. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $34mm(W_1){\times}34mm(L_1){\times}1mm(t)$, and its slot antenna size is $30mm(W_2){\times}16.75mm(L_3+L_4)$. After carrying out the simulation of each parameters, optimized values are obtained. From the fabricated and measured results, return loss of the proposed antenna satisfied Return Loss -10dB in 3.1 ~ 10.6 GHz. And measured results of gain and radiation patterns characteristics displayed for operating bands.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.630-632
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• 2016

In this paper, we propose a modified rhombus slot UWB(Ultra Wide Band) antenna with fork-shaped feeding structure. The proposed modified rhombus slot structure is eliminated upper and lower part of the basic rhombus slot shape to get ultra-wideband characteristics for UWB communication. Also, feeding structure is used to fork-shaped structure to get ultra-wideband characteristics. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $34mm(W1){\times}34mm(L1){\times}1mm(t)$, and its slot antenna size is $30mm(W2){\times}16.75mm(L3+L4)$. After the optimized process, the proposed antenna is fabricated and measured. Measured result. fabricated antenna satisfied -10 dB impedance bandwidth in UWB frequency band (3.1 ~ 10.6 GHz ). And measured results of gain and radiation patterns characteristics displayed determined for operating bands.

• 한국해양학회지
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• v.24 no.2
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• pp.84-95
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• 1989

The feeding guild classification proposed by Fauchald and Jumars (1979) and the relationship between this guild structure and the habitat environment were examined based on the quantitative polycheate samples collected on the continental shelf off the southeastern coast of Korea. Total 12 feeding guilds were found and the major feeding guilds of polychaetes were BSX (burrowing, sessile, non-jawed), SDT (surface deposit feeding, discretely motile, tentaculate), SST (surface deposit feeding, sessile, tentaculate), BMX (burrowing, motile, non-jawed), BMJ (burrowing, motile, jawed), SDJ (surface deposit feeding, discretely motile, jawed). There were more significant associations between feeding guilds and mean grain size (${\phi}$); SST and BMJ showed a positive correlation with mean phi, whereas CDJ (carnivore, discretely motile, jawed) and FDT (filter feeding, discretely motile, tentaculate), a negative value. The CDJ and CMX (carnivore, motile, non-jawed) guilds showed positive correlations with sand content, but only SST guild showed a positive correlation with clay. The heterogeneity of sediment or sorting value (${\phi}$) was highly associated with various feeding strategies of polychaetes. Surface deposit feeders and filter feeders, sessile, and tentaculate strategies were associated with poorly sorted or heterogeneous sediments. Some preliminary polychaete feeding surfaces were posed. Southern and northern coastal region composed of muddy sediment were characterized by SDJ; northern slope of mud by SST; central coast of mud by SDT, BSX; and BMX; southern offshore of sandy sediment by SDJ and IDT (interface feeding, discretely motile, tentaculate).

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.359-363
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• 2017

A slotted implantable patch antenna with microstrip feeding is proposed for industrial, scientific, and medical band applications. The result is verified by implanting the antenna in animal tissue. Further, by varying the ground width and introducing a defect into the ground structure, the antenna becomes applicable for worldwide interoperability for microwave access operations. A simulation is performed using Empire XCcel software. An Agilent vector network analyzer is used for analyzing the return loss performance. Simulated and measured results are compared. Antennas with and without defected ground structure both have key advantages including low profile, desirable return loss, good impedance matching and required bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.37-45
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• 2000

Though microstrip antenna has several advantages, it makes engineers struggle against the difficulties of narrow bandwidth and scan-blindness with probe-feeding and array configuration. To overcome these disadvantages, stacked patch and cavity-backed structure had been proposed. But this structure can not be analyzed easily because we have no concrete means to analyze it. So the algorithm to analyze the structure should be established to make it useful. This paper explained the algorithm of moment method to analyze the structure and verified it by comparing the calculated and measured results.