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RISS 인기검색어
- 검색키워드
- 저자 : Heui-Seol Roh (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Acoustic Characteristics of Sand Sediment with Circular Cylindrical Pores
Heui-Seol Roh,Suk Wang Yoon,Kang Il Lee 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.2
The acoustic pressure transmission coecient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores lled with water and air. They are also theoretically estimated with the modied Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal eects in a non-rigid porous medium with water- and air-lled cylindrical pores. In this study, the fast (rst kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coecients of the fast wave and the slow wave in the sediment slabs with water- and air-lled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.
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Heui-Seol Roh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The acoustic properties of thermoacoustic stacks made from random porous media are exper- imentaly investigated using a hybrid two-microphone impedance method and a lumped-element technique. A two-microphone impedance tube is used to measure the specific acoustic impedance (SAI) of random porous reticulated vitreous carbon (RVC) and aluminum foam. The lumped- element technique is then used to determine the experimentaly derived thermoviscous functions, which produce the propagation constant and the characteristic impedance. The measured acoustic properties of the stacks are compared to calculated results obtained by asuming paralel, capil- lary tubes. These comparisons verify that the hybrid impedance measurement can provide useful acoustic properties and that the paralel capilary-tube-based thermoacoustic theory is valuable in predicting the acoustic properties of random porous media.
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Kang Il Lee,Suk Wang Yoon,김병남,Heui-Seol Roh 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.2
The theoretical modeling of acoustic wave propagation in cancellous bone is very important in understanding interactions between the acoustic wave and cancellous bone and in improving quantitative ultrasound (QUS) techniques for the diagnosis of osteoporosis. In this study, Biot's theory and a modied Biot-Attenborough (MBA) model are applied to predict the dependences of acoustic characteristics on the frequency and on the porosity in cancellous bone. The phase velocity and the attenuation coecient predicted by both theories are compared with previous in vitro experimental measurements in terms of the mixed wave. Biot's theory successfully predicts the dependences of the phase velocity on the frequency and on the porosity in cancellous bone whereas a signicant discrepancy is observed between the predicted and the measured attenuation coecients. The MBA model is consistent with reported measurements for the dependences of both the phase velocity and the attenuation coecient on the frequency and on the porosity. These results suggest that the MBA model can be usefully employed in the eld of clinical ultrasonic bone assessment.
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Conservation of intronic minisatellite polymorphisms in the SCK1/SHC2 gene of Hominidae
Yoon, Se-Lyun,Jeong, Yunhee,Kim, Heui-Soo,Ahn, Eun-Kyung,Seol, So-Young,Lee, Sang-Yeop,Roh, Yun-Gil,Gim, Jeong-An,Hwang, Spring Yewon,Kang, Tae-Hong,Chung, Jin Woong,Leem, Sun-Hee Springer-Verlag 2014 Genes & Genomics Vol.36 No.3
The neuronally expressed Shc adaptor homolog SCK1/SHC2 gene contains an unusually high number of minisatellites. In humans, twelve different minisatellite sequences are located in introns of SCK1/SHC2 and ten of them are highly polymorphic. Here we used primers developed for humans to screen ten intronic loci of SCK1/SHC2 in chimpanzee and gorilla, and undertook a comprehensive analysis of the genomic sequence to address the evolutionary events driving these variable repeats. All ten loci amplified in chimpanzee and gorilla contained hypervariable and low-variability minisatellites. The human polymorphic locus TR1 was monomorphic in chimpanzee and gorilla, but we detected polymorphic alleles in these apes for the human monomorphic TR7 locus. When we examined the repeat size among these hominoids, there was no consistent variation by length from humans to great apes. In spite of the inconsistent evolutionary dynamics in repeat length variation, exon 16 was highly conserved between humans and great apes. These results suggest that non-coding intronic minisatellites do not show a consistent evolutionary paradigm but evolved with different patterns among each minisatellite locus. These findings provide important insight for minisatellite conservation during hominoid evolution.
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