• Journal of applied mathematics & informatics
• /
• v.6 no.3
• /
• pp.783-798
• /
• 1999

Nondeterministic finite Rabin-Scott's automata without initial and final states (2 $\omega$-FA) are considered. In this paper they are used to define so called sets of obstruction used also in various alge-braic systems and to consider similar problems for the formal languages theory. Thus we define sets of obstructions of languages(or, rather, 2$\omega$-languages) of such automata. We obtain that each 2$\omega$-language defined by 2 $\omega$-FA has the set of obstruction being a regular language. And vice versa for each regular language L(containing no proper subword of its another word) there exists a 2$\omega$ -FA having L as the set of obstructions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.3
• /
• pp.394-400
• /
• 2012

In this paper, charging modes of series resonant converter for a high voltage energy storage capacitor are compared in terms of charging time, peak resonant current, normalized peak resonant current and voltage in each operation mode. Operating principles of the full bridge series resonant converter with capacitor load are explained and analyzed in discontinuous and continuous operation mode. Based on the analysis and simulation result, $0.6{\omega}_r$ < ${\omega}_s$ < $0.75{\omega}_r$ and $1.3{\omega}_r$ < ${\omega}_s$ < $1.4{\omega}_r$ are evaluated to the best range of switching frequency for charging of an high voltage energy storage capacitor. 1.8 kJ/s SRC prototype is assembled with TI 28335 DSP controller and 40 kJ, 7 kV energy storage capacitor. Design rules based on the comparative analysis are verified by experiment.

• Current Optics and Photonics
• /
• v.3 no.3
• /
• pp.243-247
• /
• 2019

We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.

• Journal of the Korean Vacuum Society
• /
• v.10 no.3
• /
• pp.368-373
• /
• 2001

Pd/Si/Ti/Pt ohmic contact to n-type InGaAs was investigated. As-deposited contact showed non-ohmic behavior, and high specific contact resistivity of $5\times10^{-3}\Omega\textrm{cm}^2$ was achieved by rapid thermal annealing at $375^{\circ}C$ for 10 seconds. However, the specific contact resistivity decreased remarkably to $1.7\times10^{-6}\Omega\textrm{cm}^2$ and $2\times10^{-6}\Omega\textrm{cm}^2$ at $375^{\circ}C$/60sec and $425^{\circ}C$/10sec, respectively. Superior ohmic contact and non-spiking planar interface between ohmic materials and InGaAs were maintained even at $450^{\circ}C$, therefore, this thermally stable ohmic contact system is a promising candidate for compound semiconductor devices.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.44 no.3
• /
• pp.237-242
• /
• 2011

To evaluate the proximate composition and main nutritive ingredients (vitamin A, $V_A$; vitamin E, $V_E$; cholesterol; the composition of fatty acids) between eels cultured in different domestic eel farms, we analyzed edible parts of eels that were cultured in three "Water Recirculation System (WRS)" farms and three "Still-Water System (SWS)" farms. We found differences in crude protein, crude lipids and the ash content of eel meat between the farms, but water content showed no significant difference. $V_A$ and $V_E$ contents did not show meaningful differences between the two culture methods, but there was a noticeable distinction between the eel farms. In particular, $V_E$ content showed significant differences between the eels of each farm (highest farm, about 25 mg/100 g dry wt; lowest farm, about 1 mg/100 g dry wt). The fatty acids of cultured eels were composed of monoenes (MUFA, 55-60%), saturates (SFA, 30-33%), $\omega$-6 highly unsaturates (HUFA, 1.6-2%) and $\omega$-3 HUFA (8-9.2%). The MUFA content of WRS eels ($59.9{\pm}1.97%$) was higher than that of SWS eels ($55.8{\pm}0.48%$). The contents of other fatty acids were higher in SWS eels (SFA, $33.0{\pm}0.52%$; $\omega$-6FUFA, $1.98{\pm}0.2%$; $\omega$-3 HUFA, $9.2{\pm}0.67%$) than in WRS eels (SFA, $30.5{\pm}1.34%$; $\omega$-6 HUFA, $1.62{\pm}0.19%$; $\omega$-3 HUFA, $8.0{\pm}0.5%$).

• Journal of the Korean Chemical Society
• /
• v.40 no.5
• /
• pp.317-326
• /
• 1996

The frequency dependent longitudinal polarizabilities ${\alpha}zz(\omega)$ and the second hyper-polarizabilities ${\gamma}zzzz(\omega)$ of the linear polyenes, $C_4H_6\;to\;C_{30}H_{32}$, have been evaluated using the ab initio time-dependent coupled perturbed Hartree-Fock (TDCPHF) theory with the 6-31G basis set. The ratios of the dynamic properties to the static values have been examined to illustrate the relative dispersion effect and extrapolated to the infinite polymer limit. Also the effect of interchain interaction for linear and nonlinear optical properties has been investigated for $C_4H_6$ and the theoretical discussion has been described to overcome the limitation of ab initio TDHF method in the resonance region.

• Korean Journal of Environment and Ecology
• /
• v.30 no.3
• /
• pp.415-422
• /
• 2016

This study measured the vitality of Pinus densiflora and Ginko biloba and analyzed the differences of vitality levels among trees based on artificial management. Research has shown that the mean value of cambial electrical resistance (CER) on Pinus densiflora was $14.9K{\Omega}$(between $8.5{\sim}37.5K{\Omega}$), and for Ginko biloba it was $13.5K{\Omega}$ (between 6.4 and $40.5K{\Omega}$). For the purpose of artificial management, over 50% of trees were covered up with soil and about 40% of trees were not protected by fence to enable growth spaces. It was seen that the CER of trees covered up with soil was significantly higher than that of trees which were not covered up with soil. These results indicate that it is necessary to remove the soil covering for effective management of monumental trees.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.6
• /
• pp.1001-1004
• /
• 1987

In this study mathematical properties of variational solution and solution of the boundary integral equation of the linear elasticity problem are studied. It is first reviewed that a variational solution for the three-dimensional linear elasticity problem exists in the Sobolev space [ $H^{1}$(.OMEGA.)]$^{3}$ and, then, it is shown that a unique solution of the boundary integral equation is identical to the variational solution in [ $H^{1}$(.OMEGA.)]$^{3}$. To represent the boundary integral equation, the Green's formula in the Sobolev space is utilized on the solution domain excluding a ball, with small radius .rho., centered at the point where the point load is applied. By letting .rho. tend to zero, it is shown that, for the linear elasticity problem, boundary integral equation is valid for the variational solution. From this fact, one can obtain a numerical approximatiion of the variational solution by the boundary element method even when the classical solution does not exist.exist.

• Journal of the korean veterinary medical association
• /
• v.33 no.3
• /
• pp.149-154
• /
• 1997

• Journal of the Korean Mathematical Society
• /
• v.47 no.6
• /
• pp.1317-1328
• /
• 2010

In this paper, we study the properties of positive solutions for the reaction-diffusion equation $u_t$ = $\Delta_u+{\int}_\Omega u^pdx-ku^q$ in $\Omega\times(0,T)$ with nonlocal nonlinear boundary condition u (x, t) = ${\int}_{\Omega}f(x,y)u^l(y,t)dy$ $\partial\Omega\times(0,T)$ and nonnegative initial data $u_0$ (x), where p, q, k, l > 0. Some conditions for the existence and nonexistence of global positive solutions are given.