• Clinical Pain
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• v.19 no.2
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• pp.80-89
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• 2020

Objective: We compared the regenerative effects of microcurrent therapy (MT) according to the type of electric current, which were direct current microcurrent therapy (DCMT) and alternating current microcurrent therapy (ACMT) on atrophied calf muscle in cast-immobilized rabbit. Method: Rabbits were allocated into control group (sham MT), ACMT group, and DCMT group. Before starting treatment, right gastrocnemius (GCM) muscle was immobilized by cast for 2 weeks. Compound muscle action potential of tibial nerve in nerve conduction study, circumference of calf muscle using a ruler, and thickness of medial and lateral GCM muscle measured by ultrasound, cross sectional area (CSA), and proliferating cell nuclear antigen (PCNA) ratios (%) of muscle fibers were measured on the immunohistochemical analysis. Results: The mean atrophic changes (%) in right medial and lateral GCM muscle thickness, right calf circumference, and amplitude of CMAP of the right tibial nerve in ACMT group and DCMT group were significantly lower than those in control group, respectively (p<0.05). The mean CSA (μm²) of type I and type II and PCNA ratios (%) of medial and lateral GCM muscle fibers in ACMT group and DCMT group were significantly greater than those in control group, respectively (p<0.05). There were no significant differences between the ACMT group and DCMT group at all parameters. Conclusion: This study demonstrated that ACMT and DCMT showed better regeneration effect than sham MT. Microcurrent may be effective in regeneration of atrophied muscle regardless of the type of current.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.771-783
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• 2022

In this study, the feasibility of alternative tractor Roll Over Protective Structure (ROPS) designed to evaluate conditions required for testing was confirmed. In accordance with Organization for Economic Cooperation and Development (OECD) code 4, the required load energy of the tractor ROPS was determined. First, the tractor ROPS test was performed and a repeated test was performed using a simplified ROPS as an alternative tractor ROPS. The test procedure is first rearward, second lateral, and last forward based on ROPS. The load test device consists of a load cell that measures force and a LVDT that measures deformation. Precision was confirmed by calculating the relative standard deviation of the simplified ROPS repeated test. Accuracy was analyzed by calculating the mean relative error between the mean measured values in the simplified ROPS test and the tractor ROPS test. As a result, the relative standard deviation was less than 2.5% for force and 3.3% for maximum deformation overall, showed the highest precision in lateral load. The mean relative error value for force measured at the lateral load of simplified ROPS was 0.5%, showing the highest accuracy. In the front load test, the mean relative error of maximum deformation was 20.5%, showing the lowest accuracy. The mean relative error (MRE) was high in the forward load test was because of structural factors of the ROPS. The simplified ROPS model is expected to save money and time spent preparing tractors.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.155-161
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• 2023

Ion concentration polarization (ICP) is one of the essential important mechanisms for biomolecule preconcentration devices as well as a fundamental transport phenomenon found in electrodialysis, electrochemical cell, etc. The ICP triggered by externally applied voltage enables the biomolecular analyte to be preconcentrated at an arbitrary position by a locally amplified electric field inside the microchannel. Conventional preconcentration methodologies using the ICP have two limitations: uncertain equilibrium position and hydrodynamic instability of preconcentration plug. In this work, a new preconcentration method in the dead-end microchannel around cation exchange membrane was numerically studied to resolve the limitations. As a result, the numerical model showed that the analyte was concentrated at a shock front developed in a geometrically confined dead-end channel. Furthermore, the electrokinetic behaviors for preconcentration dynamics were analyzed by changing microchannel's applied voltage and volumetric charge concentration of microchannel as key parameters to describe the dynamics. This work would provide an effective means for a point-of-care platform that requires ultra-fast preconcentration method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.609-613
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• 2023

In this paper, a 1,200 V Si-based IGBT used in electric vehicles and new energy industries was designed. A field stop IGBT with a separate gate structure, which is the proposed structure, was designed to change trench depth and split gate width variables. Then, the general trench structure and electrical characteristics were compared and analyzed. As a result of conducting the trench depth experiment, it was confirmed that the breakdown voltage was the highest at 6 ㎛, and the on-state voltage drop was the lowest at 3.5 ㎛. In the separate gate width experiment, it was confirmed that the breakdown voltage decreased as the variable increased, and the on-state voltage drop increased. Therefore, it may be seen that it is preferable not to change the width of the separate gate. In addition, experiments show that there is no difference in on-state voltage drop compared to a structure in which a general field stop structure has a separate gate structure. In other words, it is determined that adding a dummy gate with a separate gate structure to the active cell will significantly improve the on-voltage drop characteristics, while confirming that the on-voltage drop does not change, and while having excellent characteristics in terms of breakdown voltage.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.99-107
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• 2017

This paper proposes a battery model coefficient correction method for improving the accuracy of existing lithium battery equivalent models. BMS(battery management system) has been researched and developed to minimize shortening of battery life by keeping SOC(state of charge) and state of charge of lithium battery used in various industrial fields such as EV. However, the cell balancing operation based on the battery cell voltage can not follow the SOC change due to the internal resistance and the capacitor. Various battery equivalent models have been studied for estimation of battery SOC according to the internal resistance of the battery and capacitors. However, it is difficult to apply the same to all the batteries, and it tis difficult to estimate the battery state in the transient state. The existing battery electrical equivalent model study simulates charging and discharging dynamic characteristics of one kind of battery with error rate of 5~10% and it is not suitable to apply to actual battery having different electric characteristics. Therefore, this paper proposes a battery model coefficient correction algorithm that is suitable for real battery operating environments with different models and capacities, and can simulate dynamic characteristics with an error rate of less than 5%. To verify proposed battery model coefficient calibration method, a lithium battery of 3.7V rated voltage, 280 mAh, 1600 mAh capacity used, and a two stage RC tank model was used as an electrical equivalent model of a lithium battery. The battery charge/discharge test and model verification were performed using four C-rate of 0.25C, 0.5C, 0.75C, and 1C. The proposed battery model coefficient correction algorithm was applied to two battery models, The error rate of the discharge characteristics and the transient state characteristics is 2.13% at the maximum.

• Reproductive and Developmental Biology
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• v.28 no.3
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• pp.181-185
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• 2004

This study was conducted to examine whether activation treatments, source of oocytes and culture conditions affect in vitro developmental ability of caprine oocytes. Mature Korean native goats were pretreated with intravaginal CIDR for 10 days. The goats were then treated with a single intramuscular injection of 1,000 IU PMSG on Day 8 or twice daily injection of a total of 70 mg FSH for 3 days from Day 8 of CIDR insertion for superovulation. All the goats were injected with 10 mg PGF/sub 2a/ on Day 8 and 400 IU hCG on Day 10 of CIDR. Oocytes were surgically collected by oviduct flushing(in vivo maturation) or direct follicle aspiration(in vitro maturation) through mid-ventral incision at 35 h after hCG injection. Fifteen to twenty oocytes were placed in TCM-199 medium containing 25 mM Hepes and hormones under mineral oil at 39℃ in a humudified atmosphere of 5% CO₂ in air for 22 to 24 h. After maturation, the oocytes were activated by electric stimulation or ionomycin + 6-DMAP. The activated oocytes were then cultured in M16, TCM-199 and mSOF media supplemented with proteins at 39℃ for 6 to 7 days. Activation treatments did not affect cleavage of the oocytes. The cleavage rates were 64.1% (41/64) in oocytes activated by electric stimulation and 76.5% (218/285) in oocytes activated by ionomycin + 6-DMAP. The proportion of development to blastocyst was 15.6% (34/218) in oocytes activated by ionomycin + 6-DMAP, but activation by electric stimulation did not support embryos developed beyond morula stage. There were no differences in the cleavage rates of activated oocytes experiencing in vivo (86.8%, 66/76) and in vitro maturation (69.0%, 127/184). However, the development rate to blastocyst stage was significantly (P<0.05) higher for oocytes matured in vivo (50.0%, 33/66) compared to in vitro (0.8%, 1/127). Culture conditions did not affect the cleavage of -activated oocytes. The cleavage rates were 51.6% (49/95) in M16, 64.3% (18/28) in TCM-199 and 81.0% (145/179) in mSOF, respectively. By contrast, the development rate of activated oocytes to stage was greater (P<0.05) for oocytes cultured in mSOF medium (23.4%, 34/145) than in M16 or TCM-199 (0.0%). Our results suggest that source of oocytes and culture conditions are major factors affecting in vitro development of caprine parthenogenetic oocytes.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.243-249
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• 2006

Porous polymer gel electrolytes (PGEs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix and polyvinylpyrolidone (PVP) as a pore-forming agent were prepared and electrochemical properties were investigated for an electric double layer capacitor (EDLC) in order to increase a permeability of an electrolyte into the PGE. Propylene carbonate (PC) and ethylene carbonate (EC) as plasticizers, and tetraethylammonium tetrafluoroborate ($TEABF_4$) as a supporting salt for the PGE were used. EDLC unit cells were assembled with the PGE and electrode comprising BP-20 and MSP-20 as activated carbon powders, Super P as a conducting agent, and P(VdF-co-HFP)/PVP as a mixed binder. Ion conductivity of PGEs increased with an increased PVP content and was the best at 7 wt% PVP, whereas electrochemical characteristics such as AC-ESR of unit cell were better in 3 wt%. And electrochemical characteristics of the unit cell with PGE were the best at a 33 : 33 weight ratio of PC to EC. Specific capacitance of a mixed plasticizer system of PE and EC was higher than that of pure PC. Ion conductivity of PGEs with a film thickness of $20{\mu}m$ was higher, but electrochemical characteristics of unit cells were higher for a $50{\mu}m$ membrane thickness. Also, the unit cell has shown the highest capacitance of 31.41 F/g and more stable electrochemical performance when PGE and electrode were hot pressed. Consequently, the optimum composition ratio of PGE for EDLCs was 23 : 66 : 11 wt% such as P(VdF-co-HFP) : PVP = 20 : 3 wt% and PC : EC = 44 : 22 wt%. In this case, $3.17{\times}10^{-3}S/cm$ of ion conductivity was achieved at the $50{\mu}m$ thickness of PGE for EDLCs. And the electrochemical characteristics of unit cells were $2.69{\Omega}$ of DC-ESR, 28 F/g of specific capacitance, and 100% of coulombic efficiency.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.288-294
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• 2007

The LSCF cathode far Solid Oxide Fuel Cell was investigated to develop high performance unit cell at intermediate temperature by modified oxalate method with different electrolytes and different pH. The LSCF powders employed La, Sr, Co and Fe oxides, oxalic acid, ethanol and $NH_4OH$ solution were synthesized with pH controlled as 2, 6, 7, 8, 9 and 10 at $80^{\circ}C$ Single crystalline phase was obtained from pH $2{\sim}9$. on the other hand, $La_2O_3$ appeared from pH 10. Very fine powder with particle size of 50 nm was obtained at calcination temperature of $800^{\circ}C$ for 4 hours. LSCF cathode synthesized at pH 7 showed the highest electric conductivity in the temperature range of $600^{\circ}C$ to $900^{\circ}C$ its value was 950 S/cm at $900^{\circ}C$ Under same synthesis conditions, polarization resistance of each LSCF cathode was changed with different calcination temperatures. As-prepared powder presented 2.52, 1.54 and $2.58\;{\Omega}$ at $600^{\circ}C$ with ScSZ, 8Y-YSZ and GDC as its electrolyte respectively after calcination at $800^{\circ}C$ for 4 hours.

• Korean Journal of Animal Reproduction
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• v.27 no.1
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• pp.87-93
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• 2003

This study was conducted to investigate the effects of embryo development by fusion condition on the nuclear transfer with brindle coated cow's ear cells. Ear cells were transferred into an enucleated oocyte and fused with cytoplasm in the fusion condition with 1.9kv/cm, 2.0kv/cm, 2.1kv/cm each 10 and 20ug duration Nuclear transfer embryo were activeted with a combination of 5ug/ml and 1.9mM 6-DMAP (4min, 4h). Fusion rate was 51∼68% range among fusion condition (1.9, 2.0, 2.1kv/cm; 10, 20us). But, cytoplasm lysis rate was increased by higher electric condition (0∼51.8% range). Each parameter's cleavage and blastocyst formation rate were 1.9kv/cm for 10us (75.8 and 19.5%), 20us (69.8 and 48.6%), 2.0kv/cm for 10us (76.9 and 20.0%), 20 us (68.5 and 40.9%), 2.1kv/cm for 10us (70.5 and 44.2%), 20 us (68.5 and 27.0%). We compared the effectiveness of cloning for between brindle coated cow's ear cells and Hanwoo fetal fibroblast cells. There was no significant differences in the fusion rate and developmental rate to the blastocyst stage. After transfer of blastocysts derived from nuclear transfer embryos, pregnancy rates of the Hanwoo fetal fibroblast cells and brindle coated cow's ear cells were checked pregnant on day 60 as assessed by ultrasonography, 40% (2/5) and 15.8% (3/19), respectively. This studies conclude that brindle coated cow's ear cells have the developmental potentiality to term by nuclear transfer. These results demonstrate that the increased the field strength was to be profitable for development of blastocyst or reduce of cytoplasm's damage than increasing the pulse duration.

• Reproductive and Developmental Biology
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• v.30 no.1
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• pp.65-70
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• 2006

This study investigated apoptosis and in vitro development of parthenogenetic preimplantation porcine embryos. In vitro matured oocytes for $42{\sim}44h$ were used. Apoptotic cell death was analyzed by using a terminal deoxynucleatidyl transferase mediated deoxyuridine 5-triphosphate nick-end tabling (TUNEL) assay. In experiment 1, oocytes were activated with two electric pulses (CH) of 1.2 kV/cm for $30{\mu}sec$ (E), E + 6-dimethylaminopurine (6-DMAP) or E + cycloheximide (CH) and cultured in PZM-3 under 5% $CO_2$ in air at $38.5^{\circ}C$. In experiment 2, oocytes were activated by E and cultured in PZM-3 or NCSU-23 under a gas atmosphere of 20% $O_2$ ($5%\;CO_2$, in air) or 5% $O_2$ $(5%\;CO_2,\;5%\;O_2\;90%\;N_2)\;at\;38.5^{\circ}C$. Oocytes activated with E+6-DMAP or E+CH showed higher blastocyst rates (36.3% and 32.5%) compared to E alone (27.7%). The frequency of apoptosis according to treatments were 5.3%, 7.7% and 7.1% respectively. Oocytes activated with E alone showed lower (P<0.05) frequency of apoptosis compared to other groups. In experiment 2, parthenotes cultured in PZM-3 showed slightly higher blastocyte rates (28.2% and 29.7%) compared to NCSU-23 (22.6% and 24.4%) regardless of atmosphere. Blastocysts generated in PZM-3 showed lower (P<0.05) apoptosis rate under 20% $O_2$ (9.2% vs 16.9%), whereas those in NCSU-23 had slightly lower apoptosis rate under 5% $O_2$ (14.0% vs 18.4%). This result represents that activation method and culture condition could affect the frequency of apoptosis as well as in vitro developmental rate.