• Journal of Ocean Engineering and Technology
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• v.16 no.5
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• pp.7-14
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• 2002

in the present paper, the hydrodynamics properties of a Rahmen type flexible porous breakwater interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at th side edges of a submerged horizontal membrane. The dual vertical membranes are extended downward and hinged at seabed. The effects of permeability, Rahmen type membrane breakwater geometry pre-tensions on membranes, relative dimensionless wave number, and incident Wave headings are thoroughly examined.

• Journal of Ocean Engineering and Technology
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• v.19 no.2 s.63
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• pp.1-11
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• 2005

In the present paper, the hydrodynamic properties of a Rahmen type flexible porous breakwater with dual fixed pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pretensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.263-275
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• 1989

Mechanical contractions and electrical activities of the fundic longitudinal and antral circular muscle fibers were investigated in order to elucidate topical differences of gastric motility. K-induced contracture was produced by exposure of muscle strips to high K Tyrode solution. Membrane potential and mechanical contraction were simultaneously recorded by conventional glass microelectrode method and single sucrose-gap technique. All experiments were performed in tris-buffered Tyrode solution which was aerated with $100%\;O_2\;and\;kept\;35^{\circ}C$. The results obtained were as follows: 1) The resting membrane potential of circular muscle cells in the antral region was about 10 mV more negative than that in the fundic region. 2) The membrane potentials decreased almost linearly as the extracellular KCI concentration was increased both in antral circular muscle cells and in fundic longitudinal muscle cells. 3) The thresholdal K concentration of K-contracture was 15 mM (membrane potential, -48 mV) for the antral circular muscle strip and 20 mM for the fundic longitudinal muscle cells. 4) The ratio of membrane permeability coefficient for $Na^+\;and\;K^+,\;P_{Na}/P_K\;({\alpha})$ was 0.065 for antral circular muscle cells and was 0.108 for fundic longitudinal muscle cells. 5) K-contracture of antral and fundic smooth muscle strips showed the contracture composed of phasic and tonic components. The amplitude of the phasic component increased sigmoidally in a dose-dependent manner, whereas that of the tonic component was maximal at a concentration of 40 mM KCI and at the concentrations above or below 40 mM KCI the amplitude was reduced. 6) The inverse relationship between the amplitude of tonic component and extracellular KCI concentration in the range of 40 to 150 mM KCI was more prominent in the antral circular muscle strip than in the fundic longitudinal muscle strip, where the amplitude of the tonic component decreased less steeply and was maintained higher at the same high K concentrations. 7) The tonic component was totally dependent on the external $Ca^{2+}$ and completely abolished by verapamil, while tile phasic component was far less dependent on the external $Ca^{2+}$ and partially suppressed by verapamil. From the above results, the following conclusions could be made. 1) The phasic component of K-contracture is produced both by intracellular $Ca^{2+}$ mobilization and by $Ca^{2+}$-influx from outside, while the tonic component is generated and maintained by the $Ca^{2+}-influx$ through the potential-dependent $Ca^{2+}$ channel. 2) The mechanism of reducing the free $Ca^{2+}$ concentration in the myoplasm seems to be more developed in the antral circular muscle than in the fundic longitudinal muscle. 3) The lower resting membrane potential of the fundic longitudinal muscle cell reflects a relatively high $P_{Na}/P_K$ ratio of about 0.108.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.277-288
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• 1995

Fracture detection has always been very attractive to the log, because it is important in many of our prospecting activities, e.g. in understanding the underground rock formation and also the fluid flow as a high permeability path. This paper demonstrates the use of high resolution borehole acoustic scanner for the detection of fractures. The tool, known as Televiewer, is the first acoustic borehole imaging system to use a focussed beam. The acoustic beams generated by a single transducer are sent toward the borehole wall, scanning the wall in a tight helix as the tool moves along the borehole. The amplitudes and travel times of the reflected signals are then measured, which produces the corresponding images. The highly resolved amplitude image allows to recognize various size of fractures and in addition to derive the rock strength from the image. Meanwhile, the travel time image itself can be directly converted to a precise caliper image, providing detailed information of deviations of the borehole shape. It also allows correction of and explanations for amplitude variations. Field measurements were carried Out at the Cheongyang study sites in Korea to illustrate the efficiency of the televiewer log.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.59-65
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• 2000

The vertical distribution of pore water pressure in the highly saturated sand layer under the oscillating water pressure is studied theoretically and experimentally. By the experiments it is shown that the water pressure acting on the sand surface propagates into the sand layer with the damping in amplitude and the lag in phase, and that the liquefaction, the state that the effective stress becomes zero, occurs under certain conditions. These experimental results are explained fairly well by the same theoretical treatment as for the ground water problems in the elastic aquifer. The main characteristics of liquefaction clarified by the analysis are as follows: 1) The depth of the liquified layer increases with the increase of the amplitude and the frequency of the oscillating water pressure. 2) The increase of the volume of the water and the air in the layer increases the liquified depth. Especially the very small amount of the air affects the liquefaction significantly. 3) The liquified depth decrease rapidly with the increase of the compressibility coefficient of the sand. 4) In the range beyond a certain value of the permeability coefficient the liquified depth decrease with the increase of the coefficient.

• Journal of the Korean Geophysical Society
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• v.4 no.3
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• pp.197-203
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• 2001

The vertical distribution of pore water pressure in the highly saturated sand layer under the oscillating water pressure (water wave) us studied theoretically and experimentally. By the experiments it is shown that the water pressure acting on the sand surface propagates into the sand layer with the damping in amplitude and the lag in phase, and that the liquefaction, the state that the effective stress become zero, occurs under certain conditions. These experimental results are explained fairly well by the same theoretical tearment as for ground water problems in the elastic aquifer. The main characteristics of liquefaction clarified by the analysis are as follows: 1) The depth of the liquified layer increases with the increase of the amplitude and the frequency of the oscillating water pressure. 2) The increase of the volume of the air in the layer increases the liquified depth. Especially the very small amount of the air affects the liquefaction significantly. 3) The liquefied depth decrese rapidly with the increase of the compressibility coefficient of the sand. 4) In the range beyond a certain value of the permeability coefficient the liquified depth decrease with the increase of the coefficient.

• The Journal of Engineering Research
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• v.4 no.1
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• pp.125-135
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• 2002

The vertical distribution of pore water pressure in the highly saturated sand layer under the oscillating water pressure (water wave) is studied theoretically and experimentally. By experiments it is shown that the water pressure acting on the sand surface propagates into the sand layer with the damping in amplitude and the lag in phase, and that the liquefaction, the state that the effective stress becomes zero, occurs under certain conditions. These experimental results are explained fairly well by the same theoretical treatment as for the ground water problems in the elastic aquifer. The main characteristics of liquefaction clarified by the analysis are as follows: 1) The depth of the liquefied layer increases with the increase of the amplitude and the frequency of the oscillating water pressure. 2) The increase of the volume of the water and the air in the layer increases the liquefied depth. Especially the very small amount of the air affects the liquefaction significantly. 3) The liquefied depth decrease rapidly with the increase of the compressibility coefficient of the sand. 4) In the range beyond a certain value of the permeability coefficient the liquefied depth decrease with the increase of the coefficient.

• Journal of the Korean Magnetics Society
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• v.14 no.1
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• pp.7-12
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• 2004

The annealing-temperature dependence of magnetic properties in compressed powder cores being composed of ball-milled F $e_{73.5}$C $u_1$N $b_3$S $i_{15.5}$ $B_{7}$ alloy powders (size 250∼850${\mu}{\textrm}{m}$) and 5 wt% of ceramic insulators has been investigated. When annealed at 5$50^{\circ}C$ for 1 h and so transformed to $\alpha$-Fe phase nanocrystalline structure with the grain size of 11 nm (electrical resistivity : 110 $\mu$Ω$.$cm), the highest effective permeability of 125 and quality factor of 53 were obtained, and the permeability persisted up to about 500 KHz. Further the core loss measured at the frequency of 50 KHz and the induction amplitude of 0.1 T was very low (230 mW/㎤). However the dc bias characteristics was not satisfactory as compared to that of conventional powder core materials(MPP, Sendust etc.). The inferior dc bias property of F $e_{73.5}$C $u_1$N $b_3$S $i_{15.5}$ $B_{7}$ alloy powder cores was attributed to the fact that the size of powder was too large for obtaining the same permeability with that of conventional materials.

• Advances in Traditional Medicine
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• v.5 no.2
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• pp.110-116
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• 2005

The effect of alcohol and aqueous extracts of the leaves and stem of Pluchea lanceolata on the spontaneous movements of both the whole worm and the nerve muscle preparation of Setaria cervi, and on the survival of microfilariae in vitro was studied. Alcohol and aqueous extracts of the leaves and stem of P. lanceolata caused the inhibition of spontaneous movements of the whole worm and the nerve muscle preparation of S. cervi, characterized by short lasting small increase in tone and amplitude of contractions followed by paralysis. The concentrations required to inhibit the movements of whole worm and nerve muscle preparations for alcohol extract were 200 and $25\;{\mu}g/ml$, and for aqueous extract were 250 and $100\;{\mu}g/ml$, respectively, suggesting a cuticular permeability barrier. Both the extracts (alcohol and aqueous) caused death of microfilariae in vitro, $LC_{50}$ and $LC_{90}$ being 12 and 18 ng/ml for alcohol extract and 25 and 40 ng/ml for aqueous extract, respectively.

• Journal of Photoscience
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• v.6 no.2
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• pp.77-83
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• 1999

Calcium has a variety of functions in neuron and muscle cells and blood clotting, especially in the visual system where dark adapted rods cotransport with Na$\^$+/ into the cell. An influx of Ca$\^$++/ flows out of the cell through the Na$\^$+/-Ca$\^$++/ exchanger. By using a modified Using chamber in order to bring in vivo environment close, we have known that Ca$\^$++/ blocks the activity of guanylate cyclase, in consequence, having an effect on the amplitude of electroretinogram (ERG). We have measured the Ca$\^$++/, K$\^$+/, and Na$\^$+/ concentration in dark and light adapted bullfrog＇s (Rana catesbeiana) vitreous humor. The calcium concentration of the light adapted bullfrog＇s vitreous humor was higher than that of the dark adapted bullfrog＇s vitreous humor This means that ion activity between the photoreceptor and vitreous humor side is light dependent and we have found that a Ca$\^$++/ channel and Ca$\^$++/K$\^$+/ exchanger exist in the vitreous humor side. Taken together permeability of Ca$\^$++/, K$\^$+/ and K$\^$+/ ion internal limiting membrane faced in the vitreous humor side has light-dependent activity during the illumination.