• Title/Summary/Keyword: mirror effect

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The Effects of Convergent Stimulation on tDCS during Mirror Therapy to Improve the Muscle Strength and Gait Ability in Chronic Stroke Patients (만성 뇌졸중 환자에서 거울 치료 시 tDCS의 융합 자극이 다리근력 및 보행능력에 미치는 효과)

  • Lee, Seung-Tae;Kim, Kyung-Yoon
    • Journal of Industrial Convergence
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    • v.18 no.4
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    • pp.51-59
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    • 2020
  • The purpose of this study was to investigate the improvement of muscle strength and gait ability of paralyzed lower extremity through convergent stimulation of tDCS(transcranial direct current stimulation) during mirror therapy with resistance exercise in chronic stroke patients. 12 patients with stroke were randomly assigned and divided into groupI(n=6) and groupII(n=6). GroupI provided NDT(neurodevelopmental treatment) and mirror therapy with sham tDCS, and groupII provided NDT and mirror therapy with tDCS. Each convergent stimulation was conducted 5 times a week, 30 minutes per session for a total of 4 weeks. All evaluation was conducted before intervention and performed after 4 weeks. Lower extremity strength showed a significant improvement in groupII compared to groupI(p<.05), and in comparison between groups by variance, significant difference in the quadriceps(p<.01) and tibialis anterior(p<.01). Gait ability showed a significant improvement in both groupI(p<.05) and groupII(p<.05), and significant difference in comparison between groups by variance(p<.01). In conclusion, mirror therapy with tDCS convergent stimulation had a positive improvement effect on paralyzed lower extremity to strength and gait ability through the overlapping interaction.

Development of an Industrial Nd:YAG Laser and its Applications (용접용 Nd:YAG 레이저의 개발과 응용)

  • 김광석
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.32-35
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    • 1989
  • A 150W industrial Nd:YAG laser was developed. The thermal lensing effect was examined and the radius and position of rear mirror were optimized for higher efficiency. The efficiency of 2.5% was achieved. Also, the performance of laser welding in fine thermocouples and between high-temperature-melting dissimilar metals were investigated.

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Effect of the Thermal Lensing on stable Region, Beam Waist and Astigmatic Compensation of Z-fold Cr4+ : YAG laser Cavity (Cr4+ : YAG 레이저에서 열 렌즈 효과에 따른 공진기의 안정영역과 빔 허리 및 비점수차의 보상)

  • Lee, Bong-Yeon
    • Korean Journal of Optics and Photonics
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    • v.17 no.5
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    • pp.447-454
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    • 2006
  • We obtained analytic solutions of boundary conditions to the stable region of Z-fold $Cr^{4+}$ : YAG laser cavity when the conditions are with and without thermal tensing effect. Also we investigated the influence of the thermal tensing effect on the stability of cavity, beam waist, and astigmatic compensation using aberration transformation matrices. The thermal tensing effect almost has no influence on the stable region of the cavity when the crystal is located in the middle of two concave mirrors and when the distances from the concave mirror to the reflecting mirror and the output coupler are the same. The beam waist, however, is affected more in a tangential plane than in a sagittal plane, and so it is difficult to have astigmatic compensation when the thermal tensing effect exists. This result means that the thermal tensing effect should be considered even for the Kerr-lens mode-locking.

Effects of Wavelength Dependent Birefringence inside a Fiber Cavity on the Fiber Laser Output Characteristics with a Nonlinear Amplifying Loop Mirror

  • Kim, Ho-Young;Kim, Kyong-Hon;Lee, El-Hang
    • Journal of the Optical Society of Korea
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    • v.2 no.2
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    • pp.64-73
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    • 1998
  • We have theoretically analyzed and experimentally observed the effects of wavelength dependent birefringence inside a laser cavity on the output characteristics of fiber lasers with a figure eight geometry. The spectral and polarization characteristics of fiber lasers are found to be very susceptible to the resultant birefringence composed of the intrinsically existing wavelength dependent birefringence and the externally induced birefringences inside the fiber. For the variation of twist-induced birefringence inside the nonlinear amplifying loop mirror, the laser output power and center wave-length of continuous wave lasers change periodically, but the polarization characteristics remains nearly unchanged. The changes of the birefringence inside the linear loop has little effect on the spectral characteristics but changes the polarization properties such as the polarization direction.

Polarimetric fiber-optic current sensor system using a twisted fiber sensing coil (비틀린 광섬유 센서코일을 이용한 편광분석형 광섬유 전류센서)

  • 송민호;김기혁
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.2
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    • pp.135-141
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    • 2004
  • We developed a polarimetric fiber-optic current sensor system for protective relaying usage. A fiber sensing coil that consisted of a length of twisted fiber and a FRM (Faraday rotator mirror) was used in order to suppress the linear birefringence effect. From the experiments with various sensing coil configurations and environmental conditions, the proposed current sensor system showed feasibility of suppressing environmental noises, and the obtained measurement stability was less than $\pm$3% at rated primary current.

Diamond micro-cutting of the difficult -to -cut materials using Electrolysis (전기분해를 이용한 난삭재의 다이아몬드 미세가공)

  • 손성민;손민기;임한석;안중환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.951-954
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    • 2000
  • This paper presents a new cutting method, i.e. diamond cutting, aided by electrolysis, in order to cut ferrous materials with diamond tools. Diamond cutting is widely applied in manufacturing ultraprecision parts such as magnetic disk, polygon mirror, spherical/non-spherical mirror and copier drum, etc. because of the diamond tool edge sharpness. In general, however, diamond cutting cannot be applied to cutting steels, because diamond tools wear excessively in cutting iron based materials like steel due to their high chemical interaction with iron in high temperature. In order to suppress the diffusion of carbon from the diamond tool and to reduce increase of cutting force due to size effect, we attempt to change chemically the compositions of iron based materials using electrolysis in a limited part which will be soon cut. Through experiments under several micro-machining and electrolysis conditions, cutting using electrolysis, compared to conventional cutting, was found to result in a great decrease of the cutting force, a better surface and much less wear tool.

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A Study on the Effect of Device Degradation Induced by Hot-Carrier to Analog Circuits (Hot-Carrier에 의한 소자 외쇠화가 아날로그 회로에 미치는 영향)

  • 류동렬;박종태;김봉렬
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.12
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    • pp.91-99
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    • 1994
  • We used CMOS current mirror and differenial amplifier to find out how the degradation of each devices in circuit affect total circuit performance. The devices in circuit wer degraded by hot-carrier generated during circuit operation and total circuit performance were changed according to the change of each device parameters. To examine the circuit performance phenomena of current mirror, we analyzed three diffent kinds of current mirrors and made correlation model between circuit performance and stressed device parameters, and compare hot-carrier immunity of these circuits. Also we analyzed how the performance of differential amplifier degraded from the initial value after hot-carrier stress incircuit operations.

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A Study on the Characteristics of Ultra-Precision Cutting for Al Alloy (Al합금의 초정밀 절삭특성 연구)

  • 김우순;김동현;난바의치
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.6
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    • pp.44-49
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    • 2003
  • To obtain the surface roughness with range from 10nm to 1nm we need the study of ultra-precision machine, cutting condition, and materials. In this paper, the optimal cutting conditions for getting mirror surface of aluminum alloy have been examined experimentally by using ultra-precision turning machine and sing1e crystal diamond tool. In generally, the cutting conditions such as feed rate and depth of cut have effect on the surface roughness in ultra-precision turning. The result of surface roughness was measured by the ZYGO New View 200. Therefore, The surface roughness and cutting conditions has been clarified. The smooth surface of aluminum alloy less than 1nm RMS, 1nm Rmax can be obtained by the ultra-precision cutting.

A Study on the Ultra-Precision Turning of Al Alloy (Al합금의 초정밀 선삭가공)

  • 김우순;채왕석;김동현;난바의치
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.416-421
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    • 2003
  • To obtain the surface roughness with range from l0nm to In n need a ultra-Precision machine, cutting condition and the study of materials. And n have to also consider the chip and vibration of diamond tool during processing. In this paper, the cutting conditions for getting mirror surface of aluminum alloy have been examined experimentally by using ultra-precision turning and single crystal diamond tool. In generally, the cutting conditions have effect on the surface roughness in ultra-precision turning. The result of surface roughness was measured by the ZYGO New View 200.

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Analog CMOS Performance Degradation due to Edge Direct Tunneling (EDT) Current in sub-l00nm Technology

  • Navakanta Bhat;Thakur, Chandrabhan-Singh
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.3 no.3
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    • pp.139-144
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    • 2003
  • We report the results of extensive mixed mode simulations and theoretical analysis to quantify the contribution of the edge direct tunneling (EDT) current on the total gate leakage current of 80nm NMOSFET with SiO2 gate dielectric. It is shown that EDT has a profound impact on basic analog circuit building blocks such as sample-hold (S/H) circuit and the current mirror circuit. A transistor design methodology with zero gate-source/drain overlap is proposed to mitigate the EDT effect. This results in lower voltage droop in S/H application and better current matching in current mirror application. It is demonstrated that decreasing the overlap length also improves the basic analog circuit performance metrics of the transistor. The transistor with zero gate-source/drain overlap, results in better transconductance, input resistance, output resistance, intrinsic gain and unity gain transition frequency.