• Journal of Astronomy and Space Sciences
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• v.5 no.2
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• pp.111-122
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• 1988

The short and long periodic perturbations and secular perturbation due to the geopotentials of degree $J_2$ and $J_3$ which affect orbital elements of a near-circular orbiting satellite are obtained by the analytical method. The singular points due to a small denominator e in the perturbation equations can be excluded using one of the methods introduced by Taff(1985), which substitutes $e_s=esin\omega,\;e_c=ecos\omega\;and\;\ell=\omega+M$ for the orbital elements e, $\omega$ and M. We determined the mean orbital elements of the meteorological satellite NOAA-10 using the Walter (1967)'s iterative procedure and compared with Brouwer's mean orbital elements determined at NASA. The mean orbital elements a, ⅰand $\Omega$ are consistent with those of NASA but the mean orgital elements e, $\omega$ and M have some deviations from those of NASA. According to the our results, it is not suitable for the polar orbiting satellites to use the Taff's proposal for excluding the singular points, which substitutes e, $\omega$ and M by $e_s=esin(\Omega+\omega),\;e_c=ecos(\Omega+\omega)\;and\;L=\Omega+\omega+M$.

• Environmental Mutagens and Carcinogens
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• v.16 no.2
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• pp.109-116
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• 1996

To study the effect of dietary $\omega 6/\omega 3$ fatty acid ratios on the preneoplastic lesions and lipid peroxidation in rat hepatocellular chemical carcinogenesis, placental glutathione S-transferase(GST-P) positive foci area and numbers, glucose 6-phosphatase(G6Pase) activity, thiobarbituric acid reactive substances (TBARS) were measured. Male Sprague-Dawley rats were fed 5 different diets-low $\omega 6/\omega 3$ ratio with fish oil (Low-F), low $\omega 6/\omega 3$ ratio with perilia oil(Low-P), moderate ratio with perilia oil(Moderate), blend of 10 different commercial fats and oils(High-BL) and high $\omega 6/\omega 3$ ratio(High)-for 8 weeks. Hepatocarcinogenesis was induced by modified Ito model. The area of GST-P positive loci was the lowest in Moderate group and in ascending order of Low-F < Low-P < High-BL < High. But statistically, only Moderate and High groups were significantly different. The number of GST-P positive foci showed the same trend as foci area. The activities of G6Pase, membrane stability marker, were increased as $\omega 6/\omega 3$ ratio decreased. Lipid peroxidation values (TBARS) were the lowest in Low-F group and it is significantly different from Moderate, High-BL and High groups. When dietary $\omega 6/\omega 3$ ratio was moderate(4.06), hepatocarcinogenesis was suppressed compared with high or low $\omega 6/\omega 3$ ratios. Blend fat, commonly consumed among Koreans, did not show any suppressive effect on carcinogenesis because of high ratio(6.7). These results suggest that dietary $\omega 6/\omega 3$ ratio influences hepatocellular chemical carcinogenesis. It is recommended that appropriate $\omega 6/\omega 3$ ratio should be around 4.0. and we recommend to use more $\omega 3$ fatty acid in food preparation to reduce the risk of hepatocarcinogenesis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.789-794
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• 2011

A coaxial-cable impedance transformer used in wideband frequency range is generally restricted to the fixed impedance transformation ratio as n2:1 or 1:n2(n: the number of coaxial cables). In this paper, we propose a new coaxial-cable impedance transformer to have an arbitrary impedance transformation ratio. We have fabricated three impedance transformers($50-{\Omega}$ to $25-{\Omega}$, $50-{\Omega}$ to $20-{\Omega}$ and $50-{\Omega}$ to $9-{\Omega}$) to confirm the operation characteristic of the suggested impedance transformer. The reflection characteristics (S11) of the fabricated $50-{\Omega}$ to $25-{\Omega}$ and $50-{\Omega}$ to $20-{\Omega}$ impedance transformer were less than -15dB over about 3-octaves frequency range and the reflection characteristic (S11) of the fabricated $50-{\Omega}$ to $9-{\Omega}$ impedance transformer was less than -15dB over about 1-octave frequency range, respectively.

• Journal of the Korean Mathematical Society
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• v.33 no.3
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• pp.481-494
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• 1996

We introduced the generalized Sobolev space $H_\omega^s$ in [4]. In this paper, we introduce the space $H_\omega^s(\Omega)$ of the generalized distributions in $H_\omega^s$ with compact supports in $\Omega$ and the local generalized Sobolev spaces $H_{\omega loc}^s(\Omega)$ of the generalized distributions on $\Omega$ which are locally in $H_\omega^s$ and study their properties.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.273-281
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• 1986

This study is focused on the correct measurement of the equations for the determination of the impedance parameters-the differential capacity of the double layer $C_d$, solution resistance $R_Q$, transfer resitance $R_i$, and adsorption pseudcapacity $C_{\phi}$/ The application of only an imaginary part of complex function of ${\omega}$ at the sinusoidal steady state indicates the following equations of total impedance: at low frequency $|Z_{LF}|=1/{\omega}_1\;C_{\phi}\;{\sqrt{1+{{\omega}_1}^2/{\omega}^2}$, at high frequency $|Z_{HF}|={\omega}_2/({\omega}_1{\omega}_3C{\phi})({\omega}^2+{{\omega}_2}^2)\;{\sqrt{{({\omega}^2+{\omega}_2{\omega}_3)}^2+{({\omega}_2{\omega}-{\omega_3{\omega})^2}}$. The values of the total impedance of cell, phase angle, and cell current that are necessary for the calculations of impedance parameters were experimentally measured from 200 to 6000Hz for the following supporting electrolytes, 0.5M $Na_2SO_4$, 1M NaCl, 19.373% sea water, 1M HCl, 1M $KNO_3$ and for $10^{-2}M$ KI and 60mM DBNA (Di-iso-Butylnitrosoamine) in these supporting electrolytes. The derived equations in this study shows that the values of impedance parameters of $C_d,\;C_{\phi},\;R_i\;and\;R_Q\;are\;15{\sim}40\;{\mu}F/cm^2,\;162{\sim}758\;{\mu}F/cm^2\;11.5{\sim}57.6\;ohm{\cdot}cm^2\;and\;0.5{\times}10^{-2}{\sim}4.1{\times}10^{-2}\;ohm{\cdot}cm^2$ respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.595-600
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• 1997

The oil content and composition of squid visera were determined to obtain data for utilization of this by-product. There was no significant difference in the glycolipid (GL) and phospholipid (PL) content in Illex argentinus and Todarodes pacificus, but neutral lipid (NL) was different (p<0.05). The viscera oil of I. argentinus contained $30.50\%$ total lipid which consisted of $96.24\%$ NL, $2.63\%$ GL, $2.37\%$ PL, and contained $644mg\%$ cholesterol. The viscera oil of T. pacificus contained $30.20\%$ total lipid which consisted of $94.82\%$ NL, $2.85\%$ GL, $2.34\%$ PL, and contained $1,224\;mg\%$ cholesterol. The NL, GL and PL of viscera oil in I. argentinus mainly consist of triglyceride $(44.01\%)$, esterified steryl glycosides $(58.95\%)$ and phosphatidyl cholines $(32.36\%)$, respertively. Those of viscera oil in T. pacificus mainly consist of triglyceride $(39.63\%)$, monogalactosyl diglycerides $(51.67\%)$ and phosphatidyl cholines $(31.98\%)$, respectively. The major fatty acids of the viscera oil of I. argentinus and T. pacificus were C16 : 0, $C16\;:\;0,\;C18\;:\;1\omega9,\;C20\;:\;4\omega6,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$. In Illex argentinus, the fatty acids of NL mainly were $C16\;:\;0,\;C18\;:\;1\omega9,\;C20\;:\;4\omega6,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$. PL were $C16\;:\;1\omega7,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$ and GL were $C18\;:\;1\omega9,\;C20\;:\;5\omega3,\;22\;:\;6\omega3$. The major fatty acids of NL in T. pacificus were $C16\;:\;0,\;C18\;:\;1\omega9,\;C20\;:\;4\omega6,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$, PL were $C16\;:\;1\omega7,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$, and GL were $C18\;:\;1\omega9,\;C20\;:\;5\omega3,\;C22\;:\;6\omega3$.

• Bulletin of the Korean Mathematical Society
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• v.49 no.6
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• pp.1291-1302
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• 2012

In this paper, we introduce a new elliptic PDE: $$\{{\nabla}{\cdot}\(\frac{|{\gamma}^{\omega}(r)|^2}{\sigma}{\nabla}v_{\omega}(r)\)=0,\;r{\in}{\Omega},\\v_{\omega}(r)=f(r),\;r{\in}{\partial}{\Omega},$$ where ${\gamma}^{\omega}={\sigma}+i{\omega}{\epsilon}$ is the admittivity distribution of the conducting material ${\Omega}$ and it is shown that the introduced elliptic PDE can replace the standard elliptic PDE with conductivity coefficient in EIT imaging. Indeed, letting $v_0$ be the solution to the standard elliptic PDE with conductivity coefficient, the solution $v_{\omega}$ is quite close to the solution $v_0$ and can show spectroscopic properties of the conducting object ${\Omega}$ unlike $v_0$. In particular, the potential $v_{\omega}$ can be used in detecting a thin low-conducting anomaly located in ${\Omega}$ since the spectroscopic change of the Neumann data of $v_{\omega}$ is inversely proportional to thickness of the thin anomaly.

• Interaction and multiscale mechanics
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• v.4 no.4
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• pp.291-311
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• 2011

To simulate the self excited torsional vibrations of rotating drill strings (DSs) in vertical bore-holes, the nonlinear wave models of homogeneous and sectional torsional pendulums are formulated. The stated problem is shown to be of singularly perturbed type because the coefficient appearing before the second derivative of the constitutive nonlinear differential equation is small. The diapasons ${\omega}_b\leq{\omega}\leq{\omega}_l$ of angular velocity ${\omega}$ of the DS rotation are found, where the torsional auto-oscillations (of limit cycles) of the DS bit are generated. The variation of the limit cycle states, i.e. birth (${\omega}={\omega}_b$), evolution (${\omega}_b&lt;{\omega}&lt;{\omega}_l$) and loss (${\omega}={\omega}_l$), with the increase in angular velocity ${\omega}$ is analyzed. It is observed that firstly, at birth state of bifurcation of the limit cycle, the auto-oscillation generated proceeds in the regime of fast and slow motions (multiscale motion) with very small amplitude and it has a relaxation mode with nearly discontinuous angular velocities of elastic twisting. The vibration amplitude increases as ${\omega}$ increases, and then it decreases as ${\omega}$ approaches ${\omega}_l$. Sectional drill strings are also considered, and the conditions of the solution at the point of the upper and lower section joints are deduced. Besides, the peculiarities of the auto-oscillations of the sectional DSs are discussed.

• Kyungpook Mathematical Journal
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• v.52 no.3
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• pp.319-325
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• 2012

The notions of (${\omega}$)compactness and (${\omega}$)paracompactness are studied in product (${\omega}$)topology. The concept of countable (${\omega}$)paracompactness is introduced and some results on this notion are obtained.

• Bulletin of the Korean Mathematical Society
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• v.55 no.3
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• pp.957-965
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• 2018

We study the class $C{\mathcal{V}} ({\Omega})$ of analytic functions f in the unit disk ${\mathbb{D}}=\{z{\in}{\mathbb{C}}$ : ${\mid}z{\mid}$ < 1} of the form $f(z)=z+{\sum}_{n=2}^{\infty}a_nz^n$ satisfying $$1+\frac{zf^{{\prime}{\prime}}(z)}{f^{\prime}(z)}{\in}{\Omega},\;z{\in}{\mathbb{D}}$$, where ${\Omega}$ is a convex and proper subdomain of $\mathbb{C}$ with $1{\in}{\Omega}$. Let ${\phi}_{\Omega}$ be the unique conformal mapping of $\mathbb{D}$ onto ${\Omega}$ with ${\phi}_{\Omega}(0)=1$ and ${\phi}^{\prime}_{\Omega}(0)$ > 0 and $$k_{\Omega}(z)={\displaystyle\smashmargin{2}{\int\nolimits_{0}}^z}{\exp}\({\displaystyle\smashmargin{2}{\int\nolimits_{0}}^t}{\zeta}^{-1}({\phi}_{\Omega}({\zeta})-1)d{\zeta}\)dt$$. Let $z_0,z_1{\in}{\mathbb{D}}$ with $z_0{\neq}z_1$. As the first result in this paper we show that the region of variability $\{{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0)\;:\;f{\in}C{\mathcal{V}}({\Omega})\}$ coincides wth the set $\{{\log}\;k^{\prime}_{\Omega}(z_1z)-{\log}\;k^{\prime}_{\Omega}(z_0z)\;:\;{\mid}z{\mid}{\leq}1\}$. The second result deals with the case when ${\Omega}$ is the right half plane ${\mathbb{H}}=\{{\omega}{\in}{\mathbb{C}}$ : Re ${\omega}$ > 0}. In this case $CV({\Omega})$ is identical with the usual normalized class of convex univalent functions on $\mathbb{D}$. And we derive the sharp upper bound for ${\mid}{\log}\;f^{\prime}(z_1)-{\log}\;f^{\prime}(z_0){\mid}$, $f{\in}C{\mathcal{V}}(\mathbb{H})$. The third result concerns how far two functions in $C{\mathcal{V}}({\Omega})$ are from each other. Furthermore we determine all extremal functions explicitly.