• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.111-143
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• 1997

We have developed a spherical FCT code in order to simulate the interaction of supernova remnants with stellar wind bubbles. We assume that the density profile of the supernova ejecta follows the Chevalier mode1(1982) where the outer portion has a power-law density distribution($\rho{\propto}\gamma^{-n}$) and the SN ejecta has a kinetic energy of $10^{51}$ ergs. The structure of wind bubble has been calculated with the stellar mass loss rate $\dot{M}=5\times10^{-6}M_{\odot}/yr$ and the wind velocity $\upsilon=2\times10^3$ km/s We have simulated seven models with different initial conditions In the first two models we computed the evolution of SNRs with n=7 and n=14 in the uniform medium The numerical results agree with the Chevalier's similarity solution at early times. When all of the power-law portion of the ejecta is swept up by the reverse shock, the evolution slowly converges to the Sedov-Taylor stage. There is not much difference between the two cases with different n's The other five models simulate SNRs produced inside wind bubbles. In model III, we consider the SN ejecta of 1.4 $M_{\odot}$ and the radius of bubble ~2.76 pc so that ratio of the mass $\alpha(=M_{W.S}/M_{ej}$ is 2. We follow the complex hydrodynamic flows produced by the interaction of SN shocks with stellar shocks and with the contact discontinuities, In the model III, the time scale for the SN shock to cross the wind shell $\tau_{cross}$ is similar to the time scale for the reverse shock to sweep the power-law density profile $\tau_{bend}$. Hence the SN shock crosses the wind shell. At late times SN shock produces another shell in the ambient medium so that we have a SNR with double shell structure. From the numerical results of the remaining models, we have found that when $\tau_{cross}/\tau_{bend}\leq2$, or equivalently when $\alpha\leq50$, the SNRs produced inside wind bubbles have double shell structure. Otherwise, either the SN shock does not cross the wind shell or even if it crosses at one time, the reverse shock reflected at the center accelerates the wind shell to merge into the SN shock Our results confirm the conclusion of Tenorio-Tagle et a1(1990).

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2523-2528
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• 2014

In the present study, at first, azo Schiff base ligand of (N,N'-bis(5-phenylazosalicylaldehyde)-ethylenediamine) ($H_2L$) has been synthesized by condensation reaction of 5-phenylazosalicylaldehyde and ethylenediamine in 2:1 molar ratio, respectively. Then, its cobalt complex (CoL) was synthesized by reaction of $Co(OAc)_2{\cdot}4H_2O$ with ligand ($H_2L$) in 1:1 molar ratio in ethanol solvent. This ligand and its cobalt complex containing azo functional groups were characterized using elemental analysis, $^1H$-NMR, UV-vis and IR spectroscopies. Subsequently, the interaction between native calf thymus deoxyribonucleic acid (ct-DNA) and CoL complex was investigated in 10 mM Tris/HCl buffer solution, pH = 7 using UV-vis absorption, thermal denaturation technique and viscosity measurements. From spectrophotometric titration experiments, the binding constant of CoL complex with ct-DNA was found to be $(2.4{\pm}0.2){\times}10^4M^{-1}$. The thermodynamic parameters were calculated by van't Hoff equation.The enthalpy and entropy changes were $5753.94{\pm}172.66kcal/mol$ and $43.93{\pm}1.18cal/mol{\cdot}K$ at $25^{\circ}C$, respectively. Thermal denaturation experiments represent the increasing of melting temperature of ct-DNA (about $0.93^{\circ}C$) due to binding of CoL complex. The results indicate that the process is entropy-driven and suggest that hydrophobic interactions are the main driving force for the complex formation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.269-270
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• 2010

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.4
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• pp.232-241
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• 2003

The interaction of incident monochromiatic waves with N bottom-mounted porous circular cylinders is investigated in the frame of three-dimensional linear potential theory. The fluid domain is divided into N+l regions i.e. a single exterior region and N interior regions, and the diffraction potential in each fluid region is expressed by an eigenfunction expansion method (Williams and Li,2000). The analytic results show that the porous structure reduces both the wave forces and the run-up wave around the cylinder. To verify the developed model, the systematic model test with a line array of porous cylinders is conducted at the wave tank (30m$\times$7m$\times$1.5m). The analytic results are in good agreement with the experimental results within measured frequency range. It is concluded that the breakwater constructed with an array of porous circular cylinders shows the performance of an effective wave barrier together with the seawater-exchange effect and is considered to have vast potentials for the use of seawater-exchanging breakwater in the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.593-600
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• 2018

Cellular automata (CA) have been applied to effective cryptographic system design. CA is superior in randomness to LFSR due to the fact that its state is updated simultaneously by local interaction. To apply these CAs to the cryptosystem, a study has been performed how to synthesize CA corresponding to given polynomials. In this paper, we analyze the recurrence relations of the characteristic polynomial of the 90 UCA and the characteristic polynomial of the 90/150 CA whose transition rule is <$00{\cdots}001$>. And we synthesize the 90/150 CA corresponding to the trinomials $x^{2^n}+x+1(n{\geq}2)$ satisfying f(x)=f(x+1) using the 90 UCA transition rule blocks and the special transition rule block. We also analyze the properties of the irreducible factors of trinomials $x^{2^n}+x+1$ and propose a 90/150 CA synthesis algorithm corresponding to $x^{2^n}+x^{2^m}+1(n{\geq}2,n-m{\geq}2)$.

• BMB Reports
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• v.31 no.2
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• pp.149-155
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• 1998

The N199H variant of the EcoRI endonuclease has about twice the catalytic activity of the wild-type. A comparison of their biochemical characteristics, using synthetic oligonucleotides 5'-dAAAACTTAAGAAAAAAAAAAA-3' (KA) and 5'-dTTTTTGAATTCTTTTTTTTTT-3' (KT), helps to define the cleavage reaction pathway of these enzymes. Both EcoRI and EcoRI variant N199H were found to cleave singlestranded KA or KT about three times faster than the double-stranded forms, although the KT oligonucleotide was more susceptible. Using the ssDNA substrate in kinetic analyses, lower $K_m$ values were obtained for the N199H variant than for the wild-type at low (50 mM), as well as high (200 mM), sodium chloride concentrations. This difference between the endonucleases is attributed to a grealter accessibility for tbe substrate by the variant, and also a higher affinity for the DNA backbone. It also appears that the relative activities of the two enzymes, particularly at high ionic strength, are proportional to their populations in the monomeric enzyme form. That is, according to gel filtration data, half of the N199H molecules exist as monomers in 200 mM NaCl, whereas those of the wild-type are mainly dimeric. Consequently, the Asp199 residue of the EcoRI endonuclease may be implicated in the protein-protein interaction leading to dimerization, as well as in coupling to DNA substrates. In summary, it is proposed that active monomeric endonuclease molecules, derived from the dimeric enzyme, recognize and form a complex with a single stranded form of the DNA substrate, which then undergoes nucleophilic substitution and cleavage.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2499-2507
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• 2012

A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.198-205
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• 1976

The integral Hellmann-Feynman Theorem of Parr is generalized to give a full significance to the off-diagonal form, and certain aspects of it are discussed. By use of the generalized form of the theorem, effects of configuration interaction to the crystal field theory are examined, taking perturbation energies of all order collectively into account. Thus, it is shown that there do not exist, especially when the field is strong, the radial integral which is common to all states characterized by ${\Gamma}$, S and m, and could be parametrized. If, however, one restricts the perturbing excited states only to those angularly undistorted and radially equally distorted, there results simple scaling of the crystal field parameter 10 Dq and Condon-Slater parameter $F^n$ defined within the framework of the classical crystal field theory.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.385-393
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• 1998

Human neutrophil elastase (HNElastase, EC 3.4.21.37), a causative factor of inflammatory diseases, was purified by Ultrogel AcA54 gel filtration and CM-Sephadex ion exchange chromatography. HNElastase was inhibited by phenylbutazone in a concentration dependent manner up to 0.4 mM, but as the concentration increased, the inhibitory effect gradually diminished. Binding of phenylbutazone to the human neutrophil elastase caused strong Raman shifts at 200, 440, and 1194 $cm^{-1}$. The peak at 1194 $cm^{-1}$ might be evidence of the presence $of\;-N=N-{\Phi}$ radical. The core area of the elastase, according to the visual molecular model of human neutrophil elastase, was structurally stable. A deeply situated active center was at the core area surrounded by hydrophobic amino acids. Directly neighboring the active site was one positively charged atom and two atoms carrying a negative charge, which enabled the enzyme and the drug to form a strong interaction. Phenylbutazone may form a binding, similar to a key & lock system to the atoms carrying opposite charges near the active site of the enzyme molecule. Furthermore, the hydrophobicity of the surrounding amino acid near the active site seemed to enhance the binding strength of phenylbutazone. Binding of phenylbutazone near the active site may cause masking of the active site, preventing the substrate from approaching the active site and inhibiting elastase activity.

• YAKHAK HOEJI
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• v.43 no.5
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• pp.642-651
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• 1999

Nonsedating antihistamines do net cause sedation in therapeutic doses because these drugs hardly cross the blood-brain barrier. Since most of the peripheral side dffects of conventional antihistamines are related to their muscarinic receptor blocking action, the present study was performed to investigate whether nonsedating antihistamines interact with the muscarinic receptors and discriminate the muscarinic receptor subtypes in the rat cerebral microsomal fraction which containes both $M_1,{\;}M_2,{\;}M_3{\;}and{\;}M_4$ receptors. Five nonsedating antihistamines at high concentrations inhibited [$^3H$]QNB binding to the muscarinic receptor in a dose-dependent manner. The inhibition curves of these drugs except loratadine which showed positive cooperativity (nH=1.55) were steep (nH=1), indicating interaction with a single homogenous population of the binding sites. Astemizole, clemizole and mequitazine increased the $K_D$ value for [$^3H$]QNB without affecting the binding site concentrations, and this increase in the $K_D$ value resulted from the ability of these drugs to slow [$^3H$]QNB-receptor association. The Ki values of astemizole, clemizole and mequitazine for the inhibition for the inhibition of [$^3H$]QNB binding to muscarinic receptor were 0.58, 5.99 and $0.007{\;}{\mu}M$, respectively. However, loratadine and terfenadine inhibited noncompetitively [$^3H$]QNB binding with the normalized $IC_50$ value of about $2{\;}{\mu}M$. These results demonstrate that; 1) astemizole, clemizole and mequitazine interact directly with the muscarinic receptor at high concentrations; 2) muscarinic receptor blocking potency of these drugs varies widely among drugs; 3) these drugs do not discriminate between muscarinic receptor subtypes.