• Smart Structures and Systems
• /
• v.29 no.4
• /
• pp.549-560
• /
• 2022

The optimum damping and tuning frequency ratio of the tuned mass damper-inerter (TMDI) for the base-isolated structure is obtained using the numerical searching technique under stationary white-noise and filtered white-noise earthquake excitation. The minimization of the isolated structure's mean-square relative displacement and absolute acceleration, as well as the maximization of the energy dissipation index, were chosen as the criteria for optimality. Using a curve-fitting technique, explicit formulae for TMDI damping and tuning frequency for white-noise excitation are then derived. The proposed empirical expressions for TMDI parameters are found to have a negligible error, making them useful for the effective design of base-isolated structures. The effectiveness of TMDI and its optimum parameters are influenced by the soil condition and isolation frequency, according to the comparison made of the optimized parameters and response with different soil profiles. The effectiveness of an optimally designed TMDI in controlling the displacement and acceleration response of the flexible isolated structure under real and pulse-type earthquakes is also observed and found to be increased as the inertance mass ratio increases.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.475-479
• /
• 1996

At present studies, we are going to suggest the new type of Perovskite derived catalysts which modify the defects of transition metals impregnated. Perovskite type catalyst is a typical mixed metal oxides, and there are "defect"s (from like that oxygen, cation, crystallic structure) were made by difference from composition, preparing method and so forth. And because this, its electro-magnetic character could be much changed. By using this phenomena, it could utilize the modification of adsorption/desorption characters as well as the catalytic activities in NOx reduction. Because perovskite type catalyst can exchange the metal of the each lattice site freely and it is possible to represent the peculiar.

• The Korean Journal of Mycology
• /
• v.13 no.4
• /
• pp.235-241
• /
• 1985

The present study was designed to investigate biosynthetic patterns of polysaccharides under catabolic repression and derepression in Saccharomyces uvarum. Correlation coefficients between polysaccharide synthesis and polyphosphate accumulation were examined, according to the culture phase and under various phosphate concentrations (free, limited, sufficient). During catabolic derepression, biosynthesis of glycogen was enhanced. rapidly and highly in the cells grown on minimal medium, compared with those grown on the complete medium. Acid soluble glycogen type was the main component of total glycogen and alkali soluble glycogen was synthesized in small amount, after 24 hr culture, at the time of almost exhaustion of sugar in the medium. Total glycogen was accumulated highly in proportion to the amount of phosphate added to the medium. It could be postulated that type 'C' isoenzyme among ALPase was directly or indirectly correlated with the glucan synthesis. Mannan synthesis indicated maximal amount at the early exponential phase and stationary phase, and also acid soluble sugars at the stationary phase. Correlation coefficient between the mannan synthesis and poly-p-'C' accumulation, and also between mannan synthesis and phospholipid content indicated 0.866 and 0.726, respectively.

• Korean Journal of Microbiology
• /
• v.45 no.3
• /
• pp.263-267
• /
• 2009

An RpoS factor is a transcriptional regulator which participates in numerous biological processes. In this work, we investigated the transcriptional regulation of proBA and proC composing proline biosynthetic pathway in Escherichia coli. While the proBA and proC genes were greatly induced in an exponential growth phase, they were dramatically repressed in a stationary growth phase in the wild type E. coli. Unlike the wild type E. coli, the proBA and proC genes were not repressed even in the stationary growth phase in its isogenic rpoS mutant. These results suggest that the RpoS factor acts as a transcriptional repressor of proBA and proC genes. The production of threonine, methionine, lysine, and arginine in the rpoS mutant were also increased by more than two times compared to its parental wild type, suggesting that the mutant is able to be used as an useful host strain for the amino acid overproduction.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1640-1645
• /
• 2004

The pumping characteristics of a single-stage disk-type drag pump ( DTDP ) are calculated,for the variation of the vertical clearance between a rotor and stator and of the radial clearance between a rotor and casing wall, by the three-dimensional direct simulation Monte Carlo (DSMC)method. The gas flow mainly belongs to the molecular transition flow region. Spiral channels of a DTDP are cut on the both the upper and lower sides of a rotating disk, but the stationary disks are planar. As a consequence of results, the vertical and radial clearances have a significant effect on the pumping performance. Experiments are performed under the outlet pressure range of 0.4 $^{\sim}$ 533 Pa. When the numerical results are compared to the experimental data, the numerical results agree well qualitatively.

• Journal of the Korean Mathematical Society
• /
• v.51 no.1
• /
• pp.163-187
• /
• 2014

We present a multi-stage Roe-type numerical scheme for a model of two-phase flows arisen from the modeling of deflagration-to-detonation transition in granular materials. The first stage in the construction of the scheme computes the volume fraction at every time step. The second stage deals with the nonconservative terms in the governing equations which produces states on both side of the contact wave at each node. In the third stage, a Roe matrix for the two-phase is used to apply on the states obtained from the second stage. This scheme is shown to capture stationary waves and preserves the positivity of the volume fractions. Finally, we present numerical tests which all indicate that the proposed scheme can give very good approximations to the exact solution.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.9
• /
• pp.1198-1206
• /
• 1997

The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10b
• /
• pp.1037-1042
• /
• 1990

The air-fuel ratio of an internal combustion engine must be controlled with accuracy for the improvements of exhaust emission and fuel consumption. Therefore, it is necessary to measure the exact instantaneous amounts of fuel and suction air, so we carried out the experiments for measuring the air flow velocity in a suction pipe of an internal combustion engine using three types of instantaneous air flowmeter. The results obtained can be summarized as follows: (1) The laminar-flow type flowmeter is able to measure both the average and the instantaneous flow rate, but it is necessary to rectify the pulsating air flow in the suction pipe. (2) The a spark-discharge type flow velocity meter is able to measure the instantaneous air velocity, but it is necessary to choose the suitable electrode form and the spark character. (3) The tandem-type hot-wire flow velocity meter indicates the instantaneous flow velocity and its flow direction.

• Journal of applied mathematics & informatics
• /
• v.27 no.5_6
• /
• pp.1033-1047
• /
• 2009

In this paper, we consider a m-type risk model with Markov-modulated premium rate. A integral equation for the conditional ruin probability is obtained. A recursive inequality for the ruin probability with the stationary initial distribution and the upper bound for the ruin probability with no initial reserve are given. A system of Laplace transforms of non-ruin probabilities, given the initial environment state, is established from a system of integro-differential equations. In the two-state model, explicit formulas for non-ruin probabilities are obtained when the initial reserve is zero or when both claim size distributions belong to the $K_n$-family, n $\in$ $N^+$ One example is given with claim sizes that have exponential distributions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.12
• /
• pp.1501-1510
• /
• 2004

The pumping characteristics of a single-stage disk-type drag pump (DTDP) are calculated for the variation of the vertical clearance between a rotor and stator by the three-dimensional direct simulation Monte Carlo (DSMC) method. The gas flow mainly belongs to the molecular transition flow region. Spiral channels of a DTDP are cut on the both the upper and lower sides of a rotating disk, but a stationary disk is planar. The interaction between molecules is described by the variable hard-sphere model. The no time counter method is used as a collision sampling technique. The vertical clearance has a significant effect on the pumping performance. Experiments are performed under the outlet pressure range of 0.4∼533 Pa. When the numerical results are compared with the experimental data, the numerical results agree well quantitatively