• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.405-414
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• 2007

In recent years, experimental and theoretical studies show that turbulent flows looking disordered have a definite structure produced repetitively with visible order. As a core structure of turbulence, hairpin vertices are believed to play a major role in developing and sustaining the turbulence process in the near wall region of turbulent boundary layers and may be regarded as the simplest conceptual model that can account for the essential features of the wall pressure fluctuations. In this work, fully developed typical hairpin vortices are focused and the associated surface pressure distributions and their corresponding spectra are estimated. On the basis of the attached eddy model, the overall surface pressure spectra are represented in terms of the eddy size distribution. The model is validated by comparison of predicted wavenumber spectra with existing empirical models, the results of direct numerical simulation (DNS) and also spatial correlations with experimental measurements.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.162-166
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• 2000

KD₂PO₄ single crystals were grown from D₂O with reagent KH₂PO₄ and the crystal structure was determined by X-ray and neutron diffraction methods. The crystals are tetragonal at room temperature, I42d, with lattice parameters of a=7.4633(7), c=6.9785(5) Å and Z=4. Intensity data were collected on an Enraf-nonius CAD4 diffractometer with a graphite monochromated MoK/sub α/ radiation (λ=0.7107Å) and on the neutron four circle single crystal diffractometer with Ge(331) monochromated neutron beam (λ=0.997Å). The structure was refined by full-matrix least-square to final R and wR values of 0.030 and 0.072, respectively, for 204 observed reflections with I>2σ(I) by X-ray diffraction and to final R=0.041 and wR=0.096 for 144 observed relfecdtions by neutron diffraction. The O…O distance of 2.516(4)Å obtained by X-ray diffraction is the same as that of 2.515(4)Å by neutron diffraction. On the other hand, the O-D/H distance of 0.84(4)Å by X-ray diffraction is considerably shorter than 1.029(7) Åby neutron diffraction. Hydrogen and deuterium can be readily distinguished by neutrons. In this crystal 66% of H-positions were substituted by D and the rest 34% occupied by H. The phase transition temperature of DKDP obtained with deuteration levels is f193K. This value agrees fairly well with the result of DSC measurement. The nuclear density distribution by neutron diffraction provides an observation of the disordered state of D/H in KD₂PO₄ at room temperature.

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.251-255
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• 2001

The structure of the lithium zinc borate LiZnBO3 has been established by single-crystal X-ray diffraction methods. It crystallizes in the triclinic space group P1(Z=2), with unit-cell parameters - $a=5.0915(9)\AA$, $b=5.059(1)\AA$, $c=6.156(1)\AA$, $V=120.6(1)\AA3$ , $\alpha=65.81(1)^{\circ}$, $\beta=65.56(1)^{\circ}$ and $\gamma=59.77(1)^{\circ}$. The structure was determined from 704 unique reflections and refined to the final residuals R=0.039 and wR=0.056. It is characterized by an association of BO3 triangles and LiO4 and ZnO4 tetrahedra. The Li and Zn atoms are disordered around the average positions between Li1 and Li2 atoms or between Zn1 and Zn2 atoms. The disorder can be described by four half-occupied positions about Li1, Li2, Zn1 and Zn2 atoms.

• Structural Engineering and Mechanics
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• v.16 no.1
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• pp.17-34
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• 2003

This paper presents a damage assessment procedure applied to periodic spring mass systems using an eigenvalue sensitivity-based method. The damage is directly related to the stiffness reduction of the damage element. The natural frequencies of periodic structures with one single disorder are found by adopting the transfer matrix approach, consequently, the first order approximation of the natural frequencies with respect to the disordered stiffness in different elements is used to form the sensitivity matrix. The analysis shows that the sensitivity of natural frequencies to damage in different locations depends only on the mode number and the location of damage. The stiffness changes due to damage can be identified by solving a set of underdetermined equations based on the sensitivity matrix. The issues associated with many possible damage locations in large structural systems are addressed, and a means of improving the computational efficiency of damage detection while maintaining the accuracy for large periodic structures with limited available measured natural frequencies, is also introduced in this paper. The incomplete measurements and the effect of random error in terms of measurement noise in the natural frequencies are considered. Numerical results of a periodic spring-mass system of 20 degrees of freedom illustrate that the proposed method is simple and robust in locating single or multiple damages in a large periodic structure with a high computational efficiency.

• BMB Reports
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• v.47 no.10
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• pp.593-598
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• 2014

RNA polymerase II carboxyl-terminal domain (RNAPII CTD) phosphatases are responsible for the dephosphorylation of the C-terminal domain of the small subunit of RNAPII in eukaryotes. Recently, we demonstrated the identification of several interacting partners with human small CTD phosphatase1 (hSCP1) and the substrate specificity to delineate an appearance of the dephosphorylation catalyzed by SCP1. In this study, using the established cells for inducibly expressing hSCP1 proteins, we monitored the modification of ${\beta}$-O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is one of the most common post-translational modifications (PTMs). To gain insight into the PTM of hSCP1, we used the Western blot, immunoprecipitation, succinylayed wheat germ agglutinin-precipitation, liquid chromatography-mass spectrometry analyses, and site-directed mutagenesis and identified the $Ser^{41}$ residue of hSCP1 as the O-GlcNAc modification site. These results suggest that hSCP1 may be an O-GlcNAcylated protein in vivo, and its N-terminus may function a possible role in the PTM, providing a scaffold for binding the protein(s).

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.381.1-381.1
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• 2014

In this study, we investigated the deposition behavior and the etch resistivity of plasma polymerized carbon hardmask (ppCHM) film with the variation of process temperature. The etch resistivity of deposited ppCHM film was analyzed by thickness measurement before and after direct contact reactive ion etching process. The physical and chemical properties of films were characterized on the Fourier transform infrared (FT-IR) spectroscope, Raman spectroscope, stress gauge, and ellipsometry. The deposition behavior of ppCHM process with the variation of temperature was correlated refractive index (n), extinction coefficient (k), intrinsic stress (MPa), and deposition rate (A/s) with the hydrocarbon concentration, graphite (G) and disordered (D) peak by analyzing the Raman and FT-IR spectrum. From this experiment we knew an optimal deposition condition for structure of carbon hardmask with the higher etch selectivity to oxide. It was shown the density of ppCHM film had 1.6~1.9 g/cm3 and its refractive index was 1.8~1.9 at process temperature, $300{\sim}600^{\circ}C$. The etch selectivity of ppCHM film was shown about 1:4~1:8 to undoped siliconoxide (USG) film (etch rate, 1300 A/min).

• Macromolecular Research
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• v.8 no.3
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• pp.103-115
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• 2000

The structural changes viewed from the molecular level have been investigated for the isothermal crystallization phenomena of polyethylene (PE) and the solvent-induced crystallization phenomenon of syndiotactic polystyrene (sPS) glassy sample. The data, which were collected by the time-resolved measurements of Fourier-transform infrared spectra, Raman spectra, synchrotron-sourced small-angle X-ray scattering, wide-angle X-ray scattering, and so on, were combined together to extract the detailed structural information in these phase transition phenomena. In the case of PE, the isothermal crystallization from the melt to the orthorhombic form was found to occur via the conformationally-disordered trans chain form, followed by the formation of the lamellar stacking structure of regular orthorhombic-type crystals. In the case of sPS, the amorphous chains in the glassy sample were found to enhance the mobility through the interaction with the injected solvent molecules, which act as a trigger to cause the conformational ordering from the random coil to the regular T$_2$G$_2$-type helical form. The thus created short helical segments were found to grow into longer helices, which gathered together to form the crystallites, as revealed by the organized coupling of the infrared, Raman and X-ray scattering data.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.26-26
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• 2011

Self-assembled monolayers (SAMs) prepared by sulfur-containing organic molecules on metal surfaces have drawn much attention for more than two decades because of their technological applications in wetting, chemical and biosensors, molecular recognition, nanolithography, and molecular electronics. In this talk, we will present self-assembly mechanism and two-dimensional (2D) structures of various organic thiol SAMs on Au(111), which are mainly demonstrated by molecular-scale scanning tunneling microscopy (STM) observation. In addition, we will provide some idea how to control 2D molecular arrangements of organic SAMs. For instance, the formation and surface structure of pentafluorobenzenethiols (PFBT) self-assembled monolayers (SAMs) on Au(111) formed from various experimental conditions were examined by means of STM. Although it is well known that PFBT molecules on metal surfaces do not form ordered SAMs, we clearly revealed for the first time that adsorption of PFBT on Au(111) at $75^{\circ}C$ for 2 h yields long-range, well-ordered self-assembled monolayers having a $(2{\times}5\sqrt{13})R30^{\circ}$ superlattice. Benzenethiols (BT) SAMs on gold usually have disordered phases, however, we have clearly demonstrated that the displacement of preadsorbed cyclohexanethiol self-assembled monolayers (SAMs) on Au(111) by BT molecules can be a successful approach to obtain BT SAMs with long-range ordered domains. Our results will provide new insight into controlling the structural order of BT or PFBT SAMs, which will be very useful in precisely tailoring the interface properties of metal surfaces in electronic devices.

• Molecules and Cells
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• v.22 no.1
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• pp.13-20
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• 2006

Hepatitis C virus (HCV) non-structural protein 5A protein (NS5A), which consists of three functional domains, is involved in regulating viral replication, interferon resistance, and apoptosis. Recently, the three-dimensional structure of the domain 1 was determined. However, currently the molecular basis for the domains 2 and 3 of HCV NS5A is yet to be defined. Toward this end, we expressed, purified the domain 2 of the NS5A (NS5A-D2), and then performed biochemical and structural studies. The purified domain 2 was active and was able to bind NS5B and PKR, biological partners of NS5A. The results from gel filtration, CD analysis, 1D $^1H$ NMR and 2D $^1H-^{15}N$ heteronuclear single quantum correlation (HSQC) spectroscopy indicate that the domain 2 of NS5A appears to be flexible and disordered.