• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.280-289
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• 1998

Voltage-sensitive ion channels contribute to establishment of the cell excitablity and the generation of the cellular function. At hamster oocytes in the primitive stage during developing process, an inward current elicited by voltage pulses was found to be carried mainly by $Ca^{2+}$. Even at present, $Ca^{2+}$ channels serve as the most probable route to pass this inward current but there is no evidence of the presence of this channels in eggs. To date, both the characteristic properties and the physiological role in the early stage of development remain unclear. Here we examined the characteristic properties of the inward current and changes in this currents at unfertilized oocytes, fertilized zygotes and two-cell embryos using whole-cell voltage clamp technique. The inward current carried reportedly by $Ca^{2+}$ was remained following removing external $Ca^{2+}$ but completely abolished by further replacement of impermeants such as tetramethylammonium ion ($TMA^+$) or $choline^+$ instead of $[Na^+]_0$. Tetrodotoxin did not affect on this inward current remained at $[Ca^{2+}]_0$-free condition. Removal of $Na^+$ ion out of the experimental solution clearly decreased the current. After adding 2mM $Ca^{2+}$ to the $Na^+$-free media, the inward current was restored. Interestingly, this current carried by either $Ca^{2+}$ or $Na^+$ was decreased by the reduction of intracellular $Cl^-$ concentration, or by $Cl^-$ channel blockers such as niflumic acid, DIDS and SITS. When $Cl^-$ concentration was lowered without changes in other ionic components, this inward current was reduced. At fertilized oocytes and two-cell embryos, the inward current carried by $Ca^{2+}$ and $Na^+$ was severely reduced. Also $Cl^-$ component could not be observed. From these results, the inward current is composed of $Ca^{2+}$, $Na^+$ and $Cl^-$ component, suggesting that the channel carrying this inward current is not selective specifically to $Ca^{2+}$. During early stage of development, the voltage-sensitive ion current seems not to contribute essentially to the cell cleavage and differentiation. The loss of $Cl^-$ component after fertilization suggests that $Cl^-$ may play a role in maintaining the viability of unfertilized ova.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.300-306
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• 1989

Physico-chemical changes caused by salting Korean radish cubes (for Kakdugi) with sodium chloride solution were investigated. Two-centimter cubes of Korean radish were soaked in saline solution of 5, 10, 15, 20 and 25 percent concentration. Optimum salinity, 3% as determined by taste, was reached in six hours at 5% strength, two hours in 10%, one hour at 15% and within one hour at concentration of 15% plus. Radish cubes salted in 5, 10. 15, 20 and 25% sodium chloride solution in a cube/solution weight ratio of 1:1 decreased in volume from 7.6 to 11.2% after one hour, and from 11.2 to 17.9% after six hours. Decrease in moisture content was from 83.0 to 75.9% in one hour and from 74.5 to 68.5% after six hours. $Potassium\;ion(K^+)$, $calcium\;ion(Ca^{2+})$ and $magnesium\;ion(Mg^{2+})$ content was significantly decreased by salting, but $sodium\;ion(Na^+)$ content greatly increased. In addition, salting caused firmness of the cubes to decrease, and cell shapes to shrink by plasmolysis.

• Geomechanics and Engineering
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• v.37 no.6
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• pp.599-614
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• 2024

To evaluate the safety status of deteriorated segments in a submarine shield tunnel during its service life, a seepage model was established based on a cross-sea shield tunnel project. This model was used to study the migration patterns of erosive ions within the shield segments. Based on these laws, the degree of deterioration of the segments was determined. Using the derived analytical solution, the internal forces within the segments were calculated. Lastly, by applying the formula for calculating safety factors, the variation trends in the safety factors of segments with different degrees of deterioration were obtained. The findings demonstrate that corrosive seawater presents the evolution characteristics of continuous seepage from the outside to the inside of the tunnel. The nearby seepage field shows locally concentrated characteristics when there is leakage at the joint, which causes the seepage field's depth and scope to significantly increase. The chlorine ion content decreases gradually with the increase of the distance from the outer surface of the tunnel. The penetration of erosion ions in the segment is facilitated by the presence of water pressure. The ion content of the entire ring segment lining structure is related in the following order: vault < haunch < springing. The difference in the segment's rate of increase in chlorine ion content decreases as service time increases. Based on the analytical solution calculation, the segment's safety factor drops more when the joint leaks than when its intact, and the change rate between the two states exhibits a general downward trend. The safety factor shows a similar change rule at different water depths and continuously decreases at the same segment position as the water depth increases. The three phases of "sudden drop-rise-stability" are represented by a "spoon-shaped" change rule on the safety factor's change curve. The issue of the poor applicability of indicators in earlier studies is resolved by the analytical solution, which only requires determining the loss degree of the segment lining's effective bearing thickness to calculate the safety factor of any cross-section of the shield tunnel. The analytical solution's computation results, however, have some safety margins and are cautious. The process of establishing the evaluation model indicates that the secondary lining made of molded concrete can also have its safety status assessed using the analytical solution. It is very important for the safe operation of the tunnel and the safety of people's property and has a wide range of applications.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.18-21
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• 1996

A continuous production of fructooligosaccharides from sucrose was investigated by fructosyltransferase immobilized on a high porous resin, Diaion HPA25. The optimum pH(5.5) and temperature(55$^{\circ}C$) of the enzyme for activity was unaltered by immobilization, and the immobilized enzyme became less sensitive to the pH change. The optimal operation conditions of the immobilized enzyme column for maximizing the productivity were as follows: 600g/L of sucrose feed concentration, flow rate of superficial space velocity 2.7h-1. When the enzyme column was run at 50$^{\circ}C$, about 8% loss of the initial activity of immobilized enzyme was observed after 30 days of continuous operation, during which high productivity of 1174g/L$.$h was achieved. The kinds of products obtained using the immobilized enzyme were almost the same as those using soluble enzymes or free cells.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1947-1949
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• 1999

Carrier lifetime in silicon power devices caused switching delay and excessive power loss at high frequency switching. We studied transient turn-on/turn-off transient characteristics of electron irradiated and proton irradiated silicon pn junction diodes. Both the electron and proton irradiation of power devices have already become a widely used practice to reduce minority carrier lifetime locally[1]. The sample is n+p junction diode, made by ion implantation on a $20\Omega.cm$ p-type wafer. We investigated turn-on/turn-off transient & breakdown voltage characteristics by digital oscilloscope. Our data show that proton irradiated samples show better performance than electron irradiated samples.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.26-27
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• 2011

This paper focuses on the zero-voltage/zero current transition voltage equalization circuit for the series connected battery cell. By adding auxiliary resonant cells at the main switching devices such as MOSFET or IGBT, zero current switching is achieved and turned off loss of switching elements is eliminated and by the voltage/second balancing of the inductor, zero voltage switching can be applied to switching element. Transformer coupling between battery cells and ZVZCT (Zero Voltage Zero Current Transition) switching method allow the fast balancing speed and high frequency operation, which reduces the size and weight of the circuit. The validity of the battery equalization is further verified using simulation involving four lithium-ion battery cell models.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.265-268
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• 1991

In the study, PPTMDSO(plasma-polymerized tetramethyldisiloxane) films were deposited on on glass substrate in a paralled plate reactor. As the function of RF power increased from 20 W to 110 W, and the substrate temperature increased from $25^{\circ}C$ to $100^{\circ}C$, the deposit ion rate, increased. When oxygen was intentionally added in monomer vapor, the concentration of Si-O-Si bonds increased while C-H, Si-H, -CH3, Si(CH3)x, -CH3, and Si-C bonds decreased in IR spectra. Thermal stability of PPTMSDO film were investigated and weight loss at $800^{\circ}C$ was 7.3 %.

• Textile Coloration and Finishing
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• v.14 no.1
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• pp.18-26
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• 2002

Chitosan has reactive amino and hydroxyl groups which can be used to chemically alter its properties under the mild reaction conditions. Thus the cationization of Tencel with Chitosan is effective to modify the fabric. To investigate the modified properties of Tencel fabric, the tests were performed under the several finishing process with enzyme/glutaraldehyde/softener. The internal structure of Tencel which has the structure of cellulose II wasn't changed by enzyme, chitosan and crosslinking agent treatment and the thermal stability was improved by chitosan and crosslinking agent treatment. Wrinkle recovery angle under the dry condition increased highly until $0.1\textrm{mol}/\ell$ of glutaraldehyde concentration, and then decreased. Tensile strength of modified Tencel fabric decreased with increasing of weight loss, but it was improved more or less by chitosan, crosslinking agent and softener. Moisture regain was improved by enzyme and chitosan treatment. And antibacterial activity showed nearly 100% on Tencel fabric treated with 0.5% chitosan and adsorption of metal ion increased with increasing of chitosan concentration.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.74-83
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• 2007

Artifacts due to inter-particle and gas-particle interactions during PM2.5 sampling were quantified by comparing the measurement results between the annular denuder-filterpack system and the filterpack system without denuder. Measurements were carried in Seoul for 10 days in each season; Nov. 2004, Jan. 2005, Mar. 2005, and Jul. 2005, respectively. In each day, two 12-h samples were obtained. The concentrations of nitrate and chloride showed seasonal variations mainly due to the availability of ammonium to neutralize nitrate or chloride. Nitrates and chloride losses were prominent in summer. Since most of ammonia was used to neutralize sulfuric acid and formed ammonium sulfate in summer, nitrate and chloride could not exist in particles and ammonium loss was smaller than other seasons.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.49-64
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• 1990

Glucoamylase from the culture filtrate of Aspergillus nicer was purified by ammonium sulfate precipitation, aceton precipitation, DEAE-cellulose ion exchange chromatography and Sephadex G-50 gel fillration. Glucoamylase was secreted into the medium upon growth on glucose, sucrose or a variety of other hexose sugars or hexose sugar polymers and little or no glucoamylase activity was found when glycerol or xylose was used as the carbon source. The optimum pH and temperature (or the maximum enzyme activity were found to be 5.0 and $50^{\circ}C$, respectively. The enzyme was considerably thermostable, for no loss of activity was observed when the enzyme was preincubated at $60^{\circ}C$ for 30 min. The enzyme activity was inhibited by 20 mM of $Hg^{2+}$, $Fe^{2+}$. The km value for starch was 0.045%.