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W. K. Lee(이원규),K. T. Yoon(윤경택),Y. M. Choi(최영만) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
In order to assist the human knee joint motion effectively, a biomechanical wearable device should perform the function of propulsion and braking of the knee joint that changes within gait cycle at the correct time. In this study, a twisted string transmission (TST) driven motor-generator system capable of assisting both propulsion and braking the knee joint during gait cycle is proposed. A twisted string transmission amplifies effectively both propulsion and braking torque through high transmission ratio and has advantages of compactness, lightness, and compliance. In this system, the human knee joint is connected to an BLDC motor and a generator by the TST. An one-way clutch bearing is installed at the generator shaft to disengage it from the TST during knee flexion phase. In the knee flexion phase, the motor generates propulsion assistance torque proportional to knee joint torque. The generator produces electricity while assisting braking of the knee joint during knee extension phase through reaction torque. From model-based parametric study, the string parameters and an electrical load of generator circuit were determined to maximize device efficiency. Finally, a testbed of the TST driven motor-generator system was built and performances of the system were evaluated through experiments.
Rb D<sub>1</sub> 전이선에서 원자결맞음에 의한 비선형 광자기 효과
문한섭,이원규,안문희,김중복,Moon, H.S.,Lee, W.K.,An, M.H.,Kim, J.B. 한국광학회 2005 한국광학회지 Vol.16 No.1
We have observed the nonlinear magneto-optic effect(NMOE) based on atomic coherence in $^{87}$ Rb D$_1$-line using the Rb vapor cell containing 50 Torr of Ne. The width of the NMOE signal was measured to be 2$\pi$${\times}$464 Hz, when the peak-to-peak B-field variation was 1 mGauss. The result of this work may be applied to a high-sensitivity magnetometer. 우리는 버퍼 가스가 포함된 Rb 원자 증기셀을 이용하여 $^{87}$ Rb원자 D$_1$전이선에서 원자결맞음에 의한 비선형 광자기 신호를 관측했다. 측정된 가장 좁은 비선형 광자기 신호의 선폭은 2$\pi$${\times}$464 Hz이고, 이 때 비선형 광자기 효과에 의한 미분형 신호의 peak-to-peak 변화에 해당하는 자기장의 변화는 약 1 mGauss로 측정되었다. 이러한 결과는 고감도 자기장 측정을 위한 광자계 연구에 응용될 수 있다.