• 전기학회논문지
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• 제68권1호
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• pp.77-82
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• 2019

In this paper, a 0.6~6GHz quad-ridge horn antenna which can be used for the antenna measurement of 5.8GHz WiFi system from lowest frequency band of mobile LTE (Long Term Evolution) is designed and implemented. The quad-ridge horn antenna has quadruple ridges of exponential function, a back-short and a cavity. Based on this structure, we design the cavity size, ridge gap and feed gap to have broadband characteristics. For implementation, the plates material of aluminum and copper are used for the horn and four ridges, respectively. And the insulator supports are used to maintain the gap between ridges. By measurement, antenna has the gain of 6.2~13.35dBi with the return loss of less than -6dB (under VSWR 3 : 1) in the entire design band. The results of this study can be widely used to the antenna studies on the mobile communication including low frequency band of LTE, the EMI measurement and the standard calibration measurement.

• Wind and Structures
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• 제34권4호
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• pp.385-394
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• 2022

Global Warming has been driven majorly by the consumption of fossil fuels. Harnessing energy from wind is viable solution towards reducing carbon footprint created due to burning such fuels, However, wind turbines have their problems of flow separation and aerodynamic stall to tackle with. In an attempt to delay the stall angle and improve the aerodynamic characteristics of the NACA 0015 symmetrical aerofoil, lateral cylindrical ridges were attached to its suction surface, at chord positions ranging from 0.1c to 0.5c. The characteristics of the original and ridged aerofoils were obtained using simultaneous pressure readings taken in a wind tunnel, at a free stream Reynolds number of R_e = 2.81 × 10⁵ for a wide range of free stream angles of attack ranging from -45° to 45°. Depending on the ridge size, a delay in stall angle varying from 5° to 20° was achieved together with the maximum increase in lift in the post-stall phases. Additionally, efforts were made to identify the optimum position for each ridge.

• ALGAE
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• 제19권3호
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• pp.277-282
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• 2004

Prymnesium patelliferum was collected from Hwajinpo, South Korea in November 2002. This is the first record of P. patelliferum in Korea waters. The characteristic shape of P. patelliferum was that of a rice grain. Cells were sub spherical or elongate, and sometimes slightly compressed. The motile cells of P. patelliferum (8-10 ㎛ long, 5-6 ㎛ broad) prossessed two equal or sub equal flagella(10.5-13 ㎛) and a short non-coiling haptonema (3-5 ㎛). The cell was covered by two layers of organic scales, which were important taxonomic characteristics. Internal scales were a narrow inflexed rim on the distal face, a thickening central and radial fibrillar pattern. External scales were very similar to internal scales with relatively tall upright rims. The ridges were in quadrants with 11-12 ridges per quadrant.

• 전자공학회논문지CI
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• 제38권3호
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• pp.55-60
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• 2001

본 논문에서는 퍼지 논리를 사용하여 지문 영상에 적용할 수 있는 효과적이 세선화 알고리즘을 제시한다. 제시하는 알고리즘은 잡영이 많이 포함된 영상이나 서로 다른 크기를 가진 영상도 효과적으로 향상시킬 수 있다. 문헌에 나타나는 대부분의 지문 영상 필터들은 특정 크기, 혹은 특정배율의 지문 영상을 대상으로 설계되었으나 본 논문이 제시하는 알고리즘은 영상 크기 변화에 따른 마스크의 크기와 계수 값의 재설계가 필요 없다.

• Animal cells and systems
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• 제6권1호
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• pp.23-33
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• 2002

A new species, Dimorphostylis namhaedoensis (Cumacea, Diastylidae) is described on the basis of the specimens collected from southern shallow coast of Korean peninsula. The new species resembles four other species, D. asiatica, D. valida, D. hisuta and D. acroplicata, in having three apical spines on the terminal margin of the male telson and three pairs of the oblique ridges on the carapace, but are obviously distinguished from them in that the pattern of the ridges on the carapace is different and the third article of the antennular peduncle is very long in female. Furthermore, the dorsal carina of the female carapace has a row of forward spines and among the three apical spines of male telson, the median spine is much smaller than the lateral ones.

• Animal Systematics, Evolution and Diversity
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• 제31권1호
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• pp.51-65
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• 2015

Two newly recorded species belonging to the genus Lamprops, family Lampropidae found in the East Sea (Sea of Japan) of Korea are reported: Lamprops carinatus Hart, 1930 and L. pseudosarsi Tsareva and Vassilenko, 1993. Lamprops carinatus is characterized by having a smooth carapace without oblique ridges and one long and two pairs of terminal unequal setae on the telson. Lamprops pseudosarsi is easily distinguished by having two pairs of oblique ridges on the carapace and one long and two pairs of terminal subequal setae on the telson. The collected specimens were congruent with the original descriptions, except for several minor differences. This is the first record of the genus Lamprops from Korea. Especially, new information on the mouthparts of these species is given, and the male of L. pseudosarsi is described for the first time. Keys are also provided to the Korean genera of the Lampropidae and species of Lamprops.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2002년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.208-211
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• 2002

The Kyunggi Bay (125-l28E, 36-38N) is a macro-tidal bay in the western central port of Korean Peninsula(Fig. 1). The Bay characterizes its feature as wide tidal flats, deep tidal channels and tidal sand ridges running in parallel to tidal flows. The macro-tidal range (up to approximately 8.6m) and consequent strong tidal currents erode the bottom sediment and selectively transport to the low-energy area forming tidal ridges or tidal flats. (omitted)

• 대한치과의사협회지
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• 제10권7호
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• pp.445-450
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• 1972

The author collected 93 male stone model and 93 female stone model of upper and lower jaw of the koreans as samples and studied the degree of attrition with age increase. Determining the degree of attrition, each normal cusp were given 40 points and calibrated into percentage. The percentage score were examined and analized, and came to the following conclusions. 1) Increased age were found graudually higher the degree of attrition at 10 to 20 age,. The degree of attrition presented localized disappearance of marginal-ridges and marginal grooves. At 30 up to 40 age, about 40 to 50% of the degree of attrition were found gradually on cusp ridges and grooves At 50 to 60 age, it was found about 70 to 80% of attrition. 2) Male score was slightly higher than female. 3) There was no significant difference between male and female score.

• Journal of Species Research
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• 제3권1호
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• pp.39-52
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• 2014

The Apiaceae genus Daucus consists of approximately 25 species (including carrots) which are characterized by the presence of bracts in pedunculate umbels, dorsally compressed mericarps, hairs on primary ridges, and uniseriately arranged spines on the secondary ridges of the fruit. Taxonomically, Daucus has been considered to be one of the most problematic genera in the Apiaceae due to the highly variable fruit morphology. Despite taxonomic controversy and economic importance of the genus, no rigorously constructed estimate of phylogenetic relationships exists. To examine generic limit and relationships among species of Daucus and its putatively related taxa, phylogenetic analyses of characters derived from nuclear ribosomal DNA ITS sequences were conducted. Two major clades emerged within Daucus, but neither of them have been previously recognized using morphological characters. The phylogeny also provides taxonomic status of recently reported new species of Daucus, D. arcanus and D. conchitae.

• Current Optics and Photonics
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• 제5권2호
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• pp.134-140
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• 2021

In this paper, I introduce a novel design method of a high performance nanophotonic beam deflector providing broadband operation, large active tunability, and signal efficiency, simultaneously. By combining thermo-optically tunable vanadium dioxide nano-ridges and a metallic mirror, reconfigurable local optical phase of reflected diffraction beams can be engineered in a desired manner over broad bandwidth. The active metagrating deflectors are systematically designed for tunable deflection of reflection beams according to the thermal phase-change of vanadium dioxide nano-ridges. Moreover, by multiplexing the phase-change supercells, a robust design of actively tunable beam splitter is also verified numerically. It is expected that the proposed intuitive and simple design method would contribute to development of next-generation optical interconnects and spatial light modulators with high performances. The author also envisions that this study would be fruitful for modern holographic displays and three-dimensional depth sensing technologies.