• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.965-967
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• 2020

Two shark species captured in Samcheok in 2006 and Ulsan in 2013, previously reported as Heptranchias perlo and Alopias pelagicus, were confirmed to in fact be Hexanchus griseus and A. superciliosus, respectively, neither of which has previously been reported in Korea. H. griseus has six gill slits and is thus distinguishable from Heptranchias perlo, which has seven gill slits. A. superciliosus is clearly distinguishable from A. pelagicus and A. vulpinus, members of the family Alopiidae, due to its large eyes and a groove extending from the center of the head to both eyes. The keys to the family Hexanchidae, including H. griseus, and the family Alopiidae, including A. superciliosus, were presented along with the morphological characteristics of these two new shark species. These two species were given the Korean names "Gi-reum-sang-eo" and "Keun-nun-hwan-do-sang-eo," with reference to their morphological characteristics and English names.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.55-56
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.228-229
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• 2004

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.141-146
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• 2009

A triangular microstrip antenna with T-shaped slits is proposed for tunable dual-band applications. The proposed antenna is designed using chip capacitors as a prototype. From this result the capacitor can be replaced to a varactor diode to control capacitance value. Since the input impedance of the antenna can be varied with the value of the chip capacitors on the T-shaped slits, the resonant frequency may be changed. The return losses are better than 10 dB at the lower band of $0.78{\sim}1.21$ GHz and 20 dB at the upper band of $1.97{\sim}2.17$ GHz, respectively. This antenna has the bandwidth of about 10 MHz and 50 MHz at each band. The peak gains of the antenna yield 0 dBi at the lower band and 3 dBi at the upper band, respectively. Details of the antenna design are described, and its performances are presented and analyzed.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.581-586
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• 2020

In this paper, the design process and method for a compact wideband loop antenna for terrestrial digital TV (DTV) and ultra high definition (UHD) TV applications was proposed. Horizontal slits were added on the two circular sectors of the proposed loop antenna in order to miniaturize the existing wideband loop antenna consisting of a square loop and two circular sectors. A CPW transmission line was inserted in the center of the lower circular sector as a feed line. The CPW feed line was designed using the 75 ohm port impedance for DTV and UHD TV applications, and a tapered center-signal line was designed to improve the impedance matching. The final designed antenna was fabricated on an FR4 substrate with a thickness of 0.8 mm. The experiment results show that the proposed compact loop antenna operates in the frequency band of 444.3-820.1 MHz for a VSWR < 2, which fully covers the DTV and UHD TV bands.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.81.1-81.1
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.54-55
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• 2004

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.233-234
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• 2010

• KIEAE Journal
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• v.1 no.2
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• pp.47-54
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• 2001

Single sound absorbers such as porous materials, panels, and Helmholts resonators have limited performance with some extents of frequency region. For example, porous materials do not attenuate low frequency sounds, while panels do not absorb high frequency sounds. Composite absorption structure with coverings, porous materials, and air gaps are an alternative for wide band sound absorption. Slits, panels, perforated panels are those materials for coverings, glass wool, mineral wool, polyester, and polyurethane are frequently used porous materials. Air gap between the porous material and background surface is one of major factors which governs the absorption characteristics of composite absorption structures, especially in the low frequency area. Calculations and measurements show that the absorption coefficients of composite absorption structure, in mid and low frequency bands, are getting higher with increased air gaps. Perforated panels rather than slits and panels are good coverings with higher number as far as absorption coefficient is concerned. Perforated panels with porous materials and 37 cm of air gaps in background have high absorption coefficients for all frequency bands, above 0.7 to 1.0. All measurements are performed in reverberation chamber, Mokpo National University, according to ISO 354 and ISO 3382.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2297-2304
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• 2002

Two-dimensional and three-dimensional finite element methods have been used to analyze the deformation behavior of a shadow mask due to thermal and tension load. The shadow mask inside the Braun tube of a TV set has numerous slits through which the electron beams are guided to land on the designed phosphor of red, green or blue. Its thermal deformation therefore causes landing shift of the electron beam and results in decolorization of a screen. For the realistic finite element analysis, the effective thermal conductivity and the effective elastic modulus arc calculated, and then the shadow mask is modeled as shell without slits. Next a transient thermal analysis of the shadow mask is performed, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermal deformation is followed, from which the landing shift of the electron beam is obtained. The present finite element scheme may be efficiently used to reduce thermal deformation of a shadow mask and in developing prototypes of a large screen flat TV.