• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.178-185
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• 1996

In this paper, a theoretical analysis of a wide band distributed mixer using a dual-gate GaAs MESFET's(DGFET) is introduced. Based on low noise mixer mode(LNM) region modeling of DGFET, variation of g/sub m/ and conversion gain are presented versus bias. The distributed mixer is composed of drain and gate transmission line, m-derived image impedance matching circuits at each input and output port, and DGFET's. Through computer simulation, wide-band characteristics of designed distributed mixer are confirmed. And, it is certificated that LO/RF isolation between gate 1 and gate 2 is obtained more than 15dB.

• Journal of information and communication convergence engineering
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• v.14 no.4
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• pp.215-221
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• 2016

We consider a design of a combined quantizer and estimator for distributed systems wherein each node quantizes its measurement without any communication among the nodes and transmits it to a fusion node for estimation. Noting that the quantization partitions minimizing the estimation error are not independently encoded at nodes, we focus on the parameter regions created by the partitions and propose a cluster-based quantization algorithm that iteratively finds a given number of clusters of parameter regions with each region being closer to the corresponding codeword than to the other codewords. We introduce a new metric to determine the distance between codewords and parameter regions. We also discuss that the fusion node can perform an efficient estimation by finding the intersection of the clusters sent from the nodes. We demonstrate through experiments that the proposed design achieves a significant performance gain with a low complexity as compared to the previous designs.

• Korean Journal of Veterinary Research
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• v.18 no.1
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• pp.39-50
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• 1978

Because of very little information available regarding the poisonous plants distributed in Jeju-Island, the author made a survey of such plants from March, 1974 to Dec., 1977. The results obtained were as follows: 1. If not all, 68 families, 137 genera and 190 species of poisonous plants distributed in Jeju-island were classified. And 190 species were divided into 137 spp. of herbs, 45 spp. of shrubs, 3 spp. of molds and 5 spp. of toadstools. 2. Relatively, a large number of poisonous plants were distributed in wild field. Jungle area, inhabited region, seashore and high mountainous area took next place gradually by the number of plants. 3. And according to their toxic chemical components or poisoning types, they were classified as 16 spp. of cyanogenetic plants, 14 spp. of oxalate-producing plants, 14 spp. of nitrate. producing plants, 10 spp. of photosensitization and 136 spp. of the other activities.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.999-1008
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• 2002

The spray structures and distribution characteristics of liquid and vapor phases in non-evaporating and evaporating Gasoline Direct Injection (GDI) fuel sprays were investigated using Laser Induced Exciplex Fluorescence (LIEF) technique. Dopants were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to study internal structure of the spray, droplet size and velocity under non-evaporating condition were measured by Phase Doppler Anemometry (PDA). Liquid and vapor phases were visualized at different moments after the start of injection. Experimental results showed that the spray could be divided into two regions by the fluorescence intensity of liquid phase: cone and mixing regions. Moreover, vortex flow of vapor phase was found in the mixing region. About 5㎛ diameter droplets were mostly distributed in the vortex flow region. Higher concentration of vapor phase due to vaporization of these droplets was distributed in this region. Particularly, higher concentration of vapor phase and lower one were balanced within the measurement area at 2ms after the start of injection.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.207-212
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• 1996

We propose an extended additional layer method (EALM) of calculating the coupling coefficient of arbitrary shaped diffraction gratings. In EALM, to determine the unperturbed field distribtution, a grating region is replaced by a new uniform layer whose dielectric constant is the average value of the dielectric constant of a grating region in both longitudinal and transverse directions. Using this method, we calculate the coupling coefficient for a five-layer distributed feedback structure device with trapezoidal and triangular gratings. The validity of this method is established by comparing the results calculated by partitioning the grating region up to five uniform layers.

• Journal of the Korean Society of Combustion
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• v.13 no.1
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• pp.31-43
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• 2008

Oxy-fuel flame has a significantly different structure from that of air-fuel flame because of its high temperature. This study is aimed to find out the difference of the oxy-fuel flame structure in order to understand reaction mechanism closely, which is crucial to design real-scale oxy-fuel combustion system. By examining pictures of counterflow flame and LIF images, we found that oxy-fuel flame had two-zone structure: fuel decomposition region and distributed CO oxidation region. In the oxy-fuel flame, OH radical was distributed intensely through the whole flame due to its higher flame temperature than crossover temperature. For showing those features of the oxy-fuel flame, 1 MW scale IFRF oxy-natural gas burner was simulated by conditional moment closure(CMC) model. Calculation results were compared with experimental data, and showed agreements in trend. In the simulated distributions of fuel decomposition/CO oxidation rates, CO oxidation region was also separated from fuel decomposition zone considerably, which showed the two-zone structure in the oxy-fuel flame.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.688-696
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• 2001

Vaporizing characteristics of two GDI injectors with different spray angles were investigated using exciplex fluorescence method. Injector I has narrower spray angle, while injector II has wider one. The exciplex system of fluorobenzene and DEMA in a non-fluorescing base fuel of hexane was employed. In quantifying concentration of fuel vapor, quenching of concentration and temperature was corrected. Droplet size and velocity were also measured by PDPA under non-vaporizing condition. From obtaining the images of liquid and vapor phases, vaporizing GDI sprays could be divided as two regions: cone and mixing regions. For injector I, vortex region was not developed. High concentration of fuel vapor due to vaporization of many fine droplets was distributed near the spray axis. For injector II, droplets with the diameter of about 10 $\mu$m were distributed in the vortex region. The vortex region had high concentration of fuel vapor due to vaporization of these droplets. Particularly, higher and lower concentrations of fuel vapor were balanced at 2ms after the start of injection for injector II.

• Animal Systematics, Evolution and Diversity
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• v.25 no.2
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• pp.167-178
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• 2009

Two poorly known and often confused pleurostomatid ciliates, Litonotus paracygnus Song, 1994 and L. pictus Gruber, 1884, were collected from the coastal waters of Yeonggeumjeong and Bongpo-port, Gangwondo in the East Sea and from the Iwon tide embankment near Ganwol-do, Chungcheongnam-do in the Yellow Sea, Korea. These species were described based on live observations, the protargol-impregnation and morphometrics of the species. Also provided are their diagnoses. The small subunit ribosomal DNA (SSU rDNA) sequences of these species were compared with previously known sequences of related species. The diagnostics of the two Litonotus species are as follows. L. paracygnus: 150-300 $\mu$m long in vivo, strongly contractile neck region, two ellipsoid macronuclei (Ma) and one micronucleus (Mi), 7 left (LSK) and 11-14 right somatic kineties (RSK), 2-4 contractile vacuoles (CV) located on the posterior end, extrusemes (Ex) distributed on the anterior region of the ventral margin only. L. pictus: about 200-600 $\mu$m long in vivo, extremely contractile, beautiful body color with rows of yellow to yellow-brownish cortical pigment granules, 12-21 Ma arranged in moniliform pattern, infrequently vermiform, 7-11 LSK and 18-26 RSK, several CV located on both margins, Ex distributed on the anterior region of the ventral margin only. In this study, this genus was firstly recorded in Korea.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.40-40
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• 2018

Pseudostellaria Pax (Caryophyllaceae) is a small genus distributed in temperate region. It consists of 25 species presenting high diversity in Asia. Pseudostellaria longipedicellata S. Lee, K. Heo & S. C. Kim was first announced as new species in 2012. Morphological characters of P. longipedicellata are closely related to those of Psedusotellaria palibiniana and Psedusotellaria okmotoi. These are distinguished from P. longipedicellata by shorter pedicel and puberulent pedicels, respectively and by being distributed allopatically between P. longipedicellata and rest of species. The complete chloroplast genome of P. longipedicellata was successfully rescued from raw reads generated by HiSeq2000. Its total length is 149,626 bp consisting of four regions: large single copy (LSC) region (81,292 bp), small single copy (SSC) region (16,984bp), and inverted repeats (IRs; 25,765 bp per each). It contained 126 genes (81 coding DNA sequence (CDS), eight rRNAs, and 37 tRNAs); 18 genes (seven CDS, four rRNAs, and seven tRNAs) are duplicated in inverted repeat regions. The overall GC content of P. longipedicellata is 36.5% and in the LSC, SSC, and IR regions were 34.3%, 29.3%, and 42.4%, respectively. Based on phylogenetic analysis of chloroplast genomes of P. longipedicellata and relatives species presents clear phylogenetic positions of Pseudostellaria genus. This chloroplast genome will be an important sequence resources for further researches of Pseudostellaria genus.

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.197-212
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• 1997

The general photometric, spectroscopic, and kinematic properties of the late type halo stars are investigated from a sample of known true halo stars. Halo stars are distributed in a lower left region of infrared (J-H) vs (H-K) color-color diagram, which is recomfirmed to be useful for selection of halo stars. They move with average velocity components of 9 km/sec, -14 km/sec, and 5 km/sec in U, V, and W directions respectively. They are distributed seperately from disk stars in a diagram of metallicity index, CaH1/TiO5 vs (R-I).