• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.921-923
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• 2003

This paper introduces Flux-Reversal Machine(FRM) and presents the design of a FRM to reduce the cogging torque. The effect of the design parameters on the characteristic and cogging torque is analyzed by finite Element Method(FEM). The considered design parameters are bifurcated teeth, chamfered magnet poles, chamfered rotor tooth tips and rotor skewing. As a result, we can find the optimum model reduced cogging torque and torque ripple in 6/8 FRM.

• Journal of Magnetics
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• 제14권1호
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• pp.36-41
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• 2009

Magneto-optical Kerr effect (MOKE) magnetometry was used to investigate magnetization reversal dynamics in 30-nm NiFe/15-nm FeMn, 15-nm FeMn/30-nm CoFe bilayers, and 30-nm NiFe/(2,10)-nm FeMn/30-nm CoFe trilayers. The in-plane magnetization components of each ferromagnetic layer, both parallel and perpendicular to the applied field, were separately determined by measuring the longitudinal and transverse MOKE hysteresis loops from both the front and back sides of the film for an oblique incident s-polarized beam. The magnetization of the FeMn/CoFe bilayer was reversed abruptly and symmetrically through nucleation and domain wall propagation, while that of the NiFe/FeMn bilayer was reversed asymmetrically with a dominant rotation. In the NiFe/FeMn/CoFe trilayers, the magnetic reversal of the two ferromagnetic layers proceeded via nucleation and domain wall propagation for 2-nm FeMn, but via asymmetric rotation for 10-nm FeMn. The exchange-biased ferromagnetic layers showed the magnetization reversal along the same path in the film plane for the decreasing and increasing field branches from transverse MOKE hysteresis loops, which can be qualitatively explained by the theoretical model of the exchange-biased ferromagnetic/antiferromagnetic systems.

• PNF and Movement
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• 제19권1호
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• pp.105-113
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• 2021

Purpose: The purpose of this study was to investigate the effect of trunk-stabilization training using stabilizing reversal and rhythmic stabilization techniques of PNF on trunk muscle strength and respiratory function in elderly stroke patients. Methods: There were 26 stroke patients included in the study. Patients were divided into two groups, and all patients performed exercise 30 min five times per week for six weeks. The experimental group performed trunk stability exercise using stabilizing reversal and rhythmic stabilization techniques of PNF, and the control group performed flexibility and strength training. Trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure were measured to determine the changes after the intervention. For statistical processing, a paired t-test was performed within the group, and the value after intervention was performed as an independent t-test to find out the difference between the two groups. Results: In the experimental group, all of the trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure showed significant differences according to the intervention. In the control group, there were statistically significant differences in trunk muscle strength and forced vital capacity, but the maximum inspiratory pressure and the maximum expiration pressure did not show any statistical change. Conclusion: From these results, it can be seen that the trunk stability exercises that use the proprioceptive neuromuscular promotion method of stable reversal and rhythm stabilization can be a good intervention for the respiratory function of stroke patients.

• BMB Reports
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• 제31권3호
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• pp.269-273
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• 1998

The objective of this study was to evaluate the reversal of multi drug resistance of human cell lines by specific inhibitors of ${\alpha}-glycosidase$ and mannosidases that had been reported to be involved in N-linked oligosaccharide processing of glycoproteins. N-methyldeoxynojirimycin, I-deoxynojirimycin, and castanospermine, which were known to be potent inhibitors of both ${\alpha}-glycosidase$ I and II, showed no activity against the multidrug resistant phenotype of the cell lines of SNU1DOX, KB-V1, and MCF-7/ADR. In contrast, I-deoxymannojirimycin, an inhibitor of mannosidase I, resulted in a slight reversal for the vinblastine resistance of the KB-V1 cell line, but did not show any activity toward the other cell lines. Parallel experiments with tunicamycin, an inhibitor of N-linked glycosylation, also resulted in no significant changes in multidrug resistant (MDR) phenotype of the cell lines tested in this work. These observations suggest that the unglycosylation of P-glycoprotein associated with the inhibitor treatments might not be correlated with the reversal of multidrug resistance of the cell lines tested in this study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1552-1553
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• 2011

The HVDC transformer which is one of the main equipments for HVDC(High Voltage Direct Current) electric power transmission systems is exposed to not only AC voltage but also the inflowing DC voltage which comes from the DC-AC converter systems. Therefore, the HVDC transformer insulation system is required to withstand the electric field stress under AC, DC and DC polarity reversal conditions. However the electric field distributions under those conditions are different because the AC electric field and DC electric field are governed by permittivity and conductivity, respectively. In this study, the changes of electric potential and electric field of conventional AC transformer insulation system under DC polarity reversal test condition were analyzed by FEM(Finite Element Method). The DC electric field stress was concentrated in the solid insulators while the AC electric field stress was concentrated in the mineral oil. In addition, the electric stress under that condition which is affected by the surface charge accumulation at the interfaces between insulators was evaluated. The stress in some parts could be higher than that of AC and DC condition, during polarity reversal test. The result of this study would be helpful for the HVDC transformer insulation system design.

• Smart Structures and Systems
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• 제30권4호
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• pp.397-410
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• 2022

It is essential to monitor the working conditions of bolt-connected joints, which are widely used in various kinds of steel structures. The looseness of bolts may directly affect the stability and safety of the entire structure. In this study, a guided wave-based method for bolt looseness detection and localization is presented for a joint structure with multiple bolts. SH waves generated and received by a small number (two pairs) of magnetostrictive transducers were used. The bolt looseness index was proposed based on the changes in the reconstructed responses excited by the time reversal signals of the measured unit impulse responses. The damage locations and local damage severities were estimated using the damage indices from several wave propagation paths. The back propagation neural network (BPNN) technique was employed to identify the local damages. Numerical and experimental studies were conducted on a lap joint with eight bolts. The results show that the total damage severity can be successfully detected under the effect of external force and measurement noise. The local damage severity can be estimated reasonably for the experimental data using the BPNN constructed by the training patterns generated from the finite element simulations.

• 한국패류학회지
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• 제31권4호
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• pp.315-322
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• 2015

이매패류의 성은 자웅이체와 자웅동체로 구분되며, 자웅이체는 동시자웅동체와 비동시자웅동체로 나누어진다. 비동시자웅동체는 계절에 따른 성의 전환을 의미한다. 일반적으로 자웅이체 이매패류의 경우 형태학적 성으로 표현되는 암, 수는 개체의 생활사 가운데 일정한 한 시기에 국한된 것이다. 개체의 성을 정확히 확인하기 위해서는 성을 표지한 후, 생활사 동안 성의 변화를 연속적으로 추적해야 한다. 이매패류에서 성전환과 비동시자웅동체는 굴과, 가리비과, 백합과 및 돌조개과 등의 이매패류에서 보고되고 있다. 이들 연구의 대부분은 동일 개체군에서 연령에 따른 성비의 변화를 증거로 이러한 결론에 도달하게 되었다. 비동시자웅동체 이매패류에서 성의 변화는 보통 방란, 방정 후 생식소의 비활성기에 일어난다. 이매패류에서 성결정과 성의 변화에는 유전적 요인과 환경적 요인 두 가지가 관여하지만, 이에 관한 이들의 영향에 관해서는 세부적인 연구가 필요하다.

• Advances in Traditional Medicine
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• 제3권2호
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• pp.100-105
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• 2003

Systematic analysis of caffeine from the commercial samples of Indian tea leaves was performed by a routine method and the content of caffeine was found to be 19.0-37.4 mg/100 g leaves. The caffeine contents from coffee seeds and chicory from Indian origin were analyzed and found to be 0.6540-1.4920 g/100 g seeds. Caffeine contents of roasted Indian chicory roots were lower than either those of Indian tea leaves or Indian coffee seeds. The multidrug resistance (MDR) reversing effects were tested on a mouse leukemia cell line of L-5178 cells by methanol extracts [M1-M15] of Indian tea leaves and coffee seeds, comparing to a control of $({\pm})-verapamil$. The effects were measured by fluorescence ratio between treated and untreated group cells. Among fifteen methanol extracts, a Gemini tea [M6] (fluorescence activity ratio 5.26) had the most potent effect for L-5178 cells. The extract M6 was 0.63-fold of $({\pm})-verapamil$. We suggest that one of mechanisms of reversal by M6 might have strong affinity to dopamine $D_1$ and D_2$ receptors. Further studies with many more tumor and normal cell lines are necessary to confirm the MDR reversal specificity of coffee methanol extracts.

• 한국응용과학기술학회지
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• 제35권4호
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• pp.1206-1212
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• 2018

본 연구에서는 강유전성 고분자를 이용하여 제작된 100 nm 이하 두께를 가지는 박막형 커페시터의 측정 주파수에 따른 분극 반전 특성을 측정, 분석하였다. 고정된 박막 두께에 대해, 인가되는 최고 전기장의 세기가 증가할수록 더 높은 항전계에서 분극 반전이 발생되었다. 고정된 최고 전기장에 대해, 박막의 두께에 무관하게 같은 항전계에서 분극 반전이 발생되었다. 모든 측정에서 로그스케일 전기장 및 로그스케일 주파수의 관계에서 약 $0.12{\pm}0.01$의 비례 상수를 보였다. 결과적으로, 강유전체 고분자 커페시터가 40 nm 두께까지는 size effect 없이 일정한 분극 반전 특성을 보였다. 본 연구는 저전압 동작 고분자 메모리 소자의 동작 예측에 유용할 것이므로 저전압에서 동작 가능한 고분자 메모리 소자의 가능성을 보여준다.

• The Journal of Korean Physical Therapy
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• 제8권1호
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• pp.15-20
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• 1996

The purpose of this study were to 1) determine the analgesic effect of 632.8 nm of helium-neon (He-Ne) laser stimulation on acupuncture point in rat and 2) determine the reversal of analgesic effect by naloxone injection. Eighteen Sprague-Dawley rats were devided into three groups : control (n=6) : laser (n=6), laser stimulation at $3.58\;J/cm^2$ ; and naloxone (n=6), 1 mg/kg of naloxone chloride inject into peritoneum before laser stimulation at $3.63J/cm^2$. Tail-flick latency were measured pretreat and posttreat with hot plate $(55^{\circ}C)$. Data were analyzed using one-way ANOVA and paired t-teat for tail-flick latency. No significant change was noted in the tail-flick latency in either control or naloxone groups. But significant increased in tail-flick latency in taller group. The results suggest that He-Ne laser induced analgesic effect, and endogenous opioids may be involved in He-Ne laser induced analgesia.