• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.255-259
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• 1985

The NMR chemical shift arising from 4d electron orbital angular momentum and 4d electron spin dipolar-nuclear Spin angular momentum interactions for a $4d^2$ system in a strong crystal field environment of octahedral symmetry has been investigated when the four fold axis is taken as the quantization axis. The NMR results are comparted with the multipolar shift at various R-values and we find that the exact results are in agreement with the multipolar shift when $R{\geqslant}0.20 nm.$ We also separate the NMR shift into the contribution of the $1/R^5$ and $1/R^7$ terms. It is found that the contribution of the $1/R^5$term to the NMR shift is dominant than the contribution of the $1/R^7$ term. Temperature dependence analysis shows that the $1/T^2$ term is the dominant contribution to the NMR shift for a $4d^2$ system but the contribution of the 1/T term may not negligible. The similar results are obtained for a $4d^1$ system from the temperature dependence analysis.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.185-199
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• 2009

Using a strain-controlled rheometer [Advanced Rheometric Expansion System (ARES)], the steady shear flow properties and the dynamic viscoelastic properties of $Antiphlamine-S^{(R)}$ lotion have been measured at $20^{\circ}C$ (storage temperature) and $37^{\circ}C$ (body temperature). In this article, the temperature dependence of the linear viscoelastic behavior was firstly reported from the experimental data obtained from a temperature-sweep test. The steady shear flow behavior was secondly reported and then the effect of shear rate on this behavior was discussed in detail. In addition, several inelastic-viscoplastic flow models including a yield stress parameter were employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models was examined by calculating the various material parameters. The angular frequency dependence of the linear viscoelastic behavior was nextly explained and quantitatively predicted using a fractional derivative model. Finally, the strain amplitude dependence of the dynamic viscoelastic behavior was discussed in full to elucidate a nonlinear rheological behavior in large amplitude oscillatory shear flow fields. Main findings obtained from this study can be summarized as follows : (1) The linear viscoelastic behavior is almostly independent of temperature over a temperature range of $15{\sim}40^{circ}C$. (2) The steady shear viscosity is sharply decreased as an increase in shear rate, demonstrating a pronounced Non-Newtonian shear-thinning flow behavior. (3) The shear stress tends to approach a limiting constant value as a decrease in shear rate, exhibiting an existence of a yield stress. (4) The Herschel-Bulkley, Mizrahi-Berk and Heinz-Casson models are all applicable and have an equivalent validity to quantitatively describe the steady shear flow behavior of $Antiphlamine-S^{(R)}$ lotion whereas both the Bingham and Casson models do not give a good applicability. (5) In small amplitude oscillatory shear flow fields, the storage modulus is always greater than the loss modulus over an entire range of angular frequencies tested and both moduli show a slight dependence on angular frequency. This means that the linear viscoelastic behavior of $Antiphlamine-S^{(R)}$ lotion is dominated by an elastic nature rather than a viscous feature and that a gel-like structure is present in this system. (6) In large amplitude oscillatory shear flow fields, the storage modulus shows a nonlinear strain-thinning behavior at strain amplitude range larger than 10 % while the loss modulus exhibits a weak strain-overshoot behavior up to a strain amplitude of 50 % beyond which followed by a decrease in loss modulus with an increase in strain amplitude. (7) At sufficiently large strain amplitude range (${\gamma}_0$>100 %), the loss modulus is found to be greater than the storage modulus, indicating that a viscous property becomes superior to an elastic character in large shear deformations.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.39.2-39.2
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• 2011

In this study we have examined the occurrence probability of solar proton events (SEPs) and their peak fluxes depending two CME parameters, linear speed and angular width. For this we used the NOAA SPE events and their associated CME data from 1997 to 2006. As a result, the probability strongly depends on two parameters as follows. In the case of halo CME whose speed is equal to and faster than 1500km/s, 36.1% are associated with SPEs but in the case of partial halo CME ($120^{\circ}{\leq}AW$ < $359^{\circ}$) whose speed is $400{\leq}V$ < $1000km/s$, only 0.9% are associated with SPEs. When we consider only front-side CMEs, 45.3% are associated with SPEs in the first case and 1.8% are associated with them in the second case. Both of whole CME data group and front-side CME data group have similar tendencies. The probabilities are different as much as 4.9 to 23 times according to the CME speed and 1.6 to 6.5 times to the angular width. We have also examined the relationship between CME speed and proton peak flux as well as its dependence on angular width (partial halo CME and halo CME), longitude (east, center, and west) and direction parameter (< 0.4 and {\geq} 0.4). Our results show that the relationships strongly depend on longitude as well as direction parameter. In addition, the relationship using the radial CME speed based on a cone model has a higher correlation coefficient than that using the projected CME speed.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.79-85
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• 2003

This study was intended to estimate Hp(10) recommended by the ICRU using the $CaSO_4:Dy,P$ element developed in the KAERI. For the estimation of Hp(10), TL response should be compensated properly through the energy range using filter materials since $CaSO_4:Dy,P$ is of severe photon energy dependent response. Various experiments and computations using Monte Carlo Code were carried out for designing filter satisfying the performance requirements of the ISO related to TL dosimeter. Under the completed filter, the relative response of $CaSO_4:Dy,P$ showed $0.75{\sim}1.0$ for photons in the range of $20{\sim}662keV$. Especially it was possible to reduce the thickness of front filter and simplify the filter combination with rear filter of larger diameter and to considerably improve angular dependence by introducing taper to the filler.

• Progress in Medical Physics
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• v.18 no.1
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• pp.48-54
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• 2007

This study is to develope a phantom for MOSFET (Metal Oxide Semiconductors Field Effect Transistors) dosimetry and compare the dosimetric properties of standard MOSFET and microMOSFET with the phantom. In this study, the developed phantom have two shape: one is the shape of semi-sphere with 10cm diameters and the other one is the flat slab of $30{\times}30cm$with 1 cm thickness. The slab phantom was used for calibration and characterization measurements of reproducibility, linearity and dose rate dependency. The semi-sphere phantom was used for angular and directional dependence on the types of MOSFETs. The measurements were conducted under $10{\times}10cm^2$ fields at 100cm SSD with 6MV photon of Clinac (21EX, Varian, USA). For calibration and reproducibility, five standard MOSFETS and microMOSFETs were repeatedly Irradiated by 200cGy five times. The average calibration factor was a range of $1.09{\pm}0.01{\sim}1.12{\pm}0.02mV/cGy$ for standard MOSFETS and $2.81{\pm}0.03{\sim}2.85{\pm}0.04 mV/cGy$ for microMOSFETs. The response of reproducibility in the two types of MOSFETS was found to be maximum 2% variation. Dose linearity was evaluated In the range of 5 to 600 cGy and showed good linear response with $R^2$ value of 0.997 and 0.999. The dose rate dependence of standard MOSFET and microMOSFET was within 1% for 200 cGy from 100 to 500MU/min. For linearity, reproducibility and calibration factor, two types of MOSFETS showed similar results. On the other hand, the standard MOSFET and microMOSFET were found to be remarkable difference in angular and directional dependence. The measured angular dependence of standard MOSFET and microMOSFET was also found to be the variation of 13%, 10% and standard deviation of ${\pm}4.4%,\;{\pm}2.1%$. The directional dependence was found to be the variation of 5%, 2% and standard deviation of ${\pm}2.1%,\;{\pm}1.5%$. Therefore, dose verification of radiation therapy used multidirectional X-ray beam treatments allows for better the use of microMOSFET which has a reduced angular and directional dependence than that of standard MOSFET.

• Journal of Pharmaceutical Investigation
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• v.36 no.1
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• pp.31-38
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• 2006

Using a Rheometries Dynamic Analyzer (RDA II), the dynamic viscoelastic properties of a semi-solid ointment base (vaseline) in large amplitude oscillatory shear flow fields were measured over a temperature range of $25{\sim}45^{\circ}C$ and the linear viscoelastic behavior in small amplitude oscillatory shear flow fields was investigated over a wide range of angular frequencies. In this article, the nonlinear viscoelastic behavior was reported from the experimentally obtained data and the effect of temperature on this behavior was discussed in detail. In addition, the angular frequency and temperature dependencies of a linear viscoelastic behavior were explained. Finally, the applicability of a time-temperature superposition principle originally developed for polymeric materials was examined using a shift factor. Main results obtained from this study can be summarized as follows : (1) At very small strain amplitude region, vaseline shows a linear viscoelastic behavior independent of the imposed deformation magnitudes. Above a critical strain amplitude $({\gamma}_{0}=0.1{\sim}0.2%)$, however, vaseline exhibits a nonlinear viscoelastic behavior ; indicating that both the storage modulus and dynamic viscosity are sharply decreased with increasing deformation magnitude. (2) In large amplitude oscillatory shear flow fields, an elastic behavior (storage modulus) has a stronger strain amplitude dependence and begins to show a nonlinear behavior at a smaller strain amplitude region than does a viscous behavior (dynamic viscosity). (3) In small amplitude oscillatory shear flow fields, the storage modulus as well as the loss modulus are continuously increased as an increase in angular frequency and an elastic nature is always superior to a viscous behavior over a wide range of angular frequencies. (4) A time-temperature superposition principle can successfully be applicable to vaseline. This finding allows us to estimate the dynamic viscoelastic behavior of vaseline over an extraordinarily extended range (11 decades) of angular frequencies inaccessible from the experimentally measured range (4 decades).

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.35.1-35.1
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• 2019

We present a statistical analysis on the spin-orbit alignment of dark matter halo pairs in cosmological simulations. The alignment is defined as the angular concurrence between the halo spin vector (${\vec{S}}$) and the orbital angular momentum vector (${\vec{L}}$) of the major companion. We identify interacting halo pairs with the mass ratios from 1:1 to 1:3, with the halo masses of 10.8 < $Log(M_{halo}/M_{sun}$) < 13.0, and with the separations smaller than a sum of their virial radii ($R_{12}<R_{1,vir}+R_{2,vir}$). Based on the total energy ($E_{12}$), the pairs are classified into flybys ($E_{12}$ > 0) and mergers ($E_{12}{\leq}0$). By measuring the angle (${\theta}_{SL}$) between ${\vec{S}}$ and ${\vec{L}}$, we confirm a strong spin-orbit alignment signal such that the halo spin is preferentially aligned with the orbital angular momentum of the major companion. We find that the signal of the spin-orbit alignment for the flyby is weaker than that for the merger. We also find an unexpected excess signal of the spin-orbit alignment at $cos{\theta}_{SL}{\sim}0.25$. Both the strength of the spin-orbit alignment and the degree of the excess depend only on the environment. We conclude that the halo spin is determined by the accretion in a preferred direction set by the ambient environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1050-1053
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• 2001

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/HiO(300$\AA$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in 45$^{\circ}$Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO(300$\AA$)/NiFe(450$\AA$) was shown in the range of about $\pm$50 Oe.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.207-210
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• 2004

The deformation behavior of copper during equal channel angular pressing (ECAP) was calculated using a three-dimensional version of a constitutive model based on the dislocation density evolution. Finite element simulations of the variation of the dislocation density and the dislocation cell size with the number of ECAP passes are reported. The calculated stress, strain and cell size are compared with the experimental data for Cu deformed by ECAP in a modified Route C regime. The results of FEM analysis were found to be in good agreement with the experiments. After a rapid initial decrease down to about 200 nm in the first ECAP pass, the average cell size was found to change little with further passes. Similarly, the strength increased steeply after the first pass, but tended to saturate with further pressings. The FEM simulations also showed strain non-uniformities and the dependence of the resulting strength on the location within the workpiece.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.618-625
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• 1991

A general expression adopting a nonmultipole expansion method is derived for pseudocontact contribution to the NMR chemical shift arising from the electron orbital angular momentum and electron spin dipolar-nuclear spin angular momentum interaction of $3d^9$ system in a strong crystal field of tetragonally distorted tetrahedral symmetry. From this expression all the multipolar term are determined and the exact solution of ${\Delta}$B/B(ppm) is compared with the multipolar term. The $1/R^5$ term in the multipolar terms contributes dominantly to the NMR chemical shift but the other terms are certainly significant except that of the <111> axis. In addition, an analysis of the temperature dependence of the NMR chemical shift further illustrates that considerable care must be taken in interpeting NMR results in paramagnetic system.