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Yi Liu,Yiming Yu,Tuanwei Zhang,Renlong Xiong,Hyoung Seop Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.4
A new image-processing method based on block-gradient segmentation was proposed to measure the volume fraction ofmechanical twins in metallographic images. The processing results showed that this automatic method could be used forrapid and effective measure of the twin-volume fractions of twinning-induced plasticity steels in metallographic images underdifferent strain conditions. The entire processing time for each image is relatively short, which would benefit researchersprocessing a large number of metallographic images. This method may pave a way to develop a simple, effective plug-in tomeasure rapidly the twin-volume fractions in the software for metallographic observations, and it would be beneficial forpreliminary analysis of microstructural evolutions and subsequent characterization of mechanical twins by high-resolutionmicroscopy using electron microscopy.
Emergency Monitoring System Based on a Newly-Developed Fall Detection Algorithm
Yi, Yun Jae,Yu, Yun Seop The Korea Institute of Information and Commucation 2013 Journal of information and communication convergen Vol.11 No.3
An emergency monitoring system for the elderly, which uses acceleration data measured with an accelerometer, angular velocity data measured with a gyroscope, and heart rate measured with an electrocardiogram, is proposed. The proposed fall detection algorithm uses multiple parameter combinations in which all parameters, calculated using tri-axial accelerations and bi-axial angular velocities, are above a certain threshold within a time period. Further, we propose an emergency detection algorithm that monitors the movements of the fallen elderly person, after a fall is detected. The results show that the proposed algorithms can distinguish various types of falls from activities of daily living with 100% sensitivity and 98.75% specificity. In addition, when falls are detected, the emergency detection rate is 100%. This suggests that the presented fall and emergency detection method provides an effective automatic fall detection and emergency alarm system. The proposed algorithms are simple enough to be implemented into an embedded system such as 8051-based microcontroller with 128 kbyte ROM.
PSPICE Modeling of Commercial ICs for Switch-Mode Power Supply (SMPS) Design and Simulation
Yi, Yun-Jae,Yu, Yun-Seop The Korea Institute of Information and Commucation 2011 Journal of information and communication convergen Vol.9 No.1
PSPICE modeling of a commercial LED driver IC (TOP245P) and PC817A optocoupler is proposed for the switch-mode power supply (SMPS) (applicable to LED driver) design and simulation. An analog behavioral model of the TOP245P IC including the shunt regulator, under-voltage(UV) detection, over-voltage(OV) shut-down and SR flip-flop is developed by using PSPICE. The empirical equation of PC817A current transfer ratio (CTR) is fitted from the datasheet of PC817A. Two types of SMPSs are simulated with the averaged-model and switching-model. The simulation results by the proposed PSPICE models are in good agreement with those in the data sheet and an experimental data.
( Song Yeon Yi ),( Young Ju Kim ),( Dong Yeop Lee ),( Jae Ho Yu ),( Jin Seop Kim ),( Soung Gil Kim ),( Ji Heon Hong ) 대한물리치료학회 2021 대한물리치료학회지 Vol.33 No.6
Purpose: This study investigated the effects of open kinetic chain (OKC) exercise for the gastrocnemius (GCM) and tibialis anterior (TA) muscles on static and dynamic balance and muscle strength. Methods: We recruited 21 healthy participants, dividing them into 3 groups (GCM, TA, and non-exercise). Each group contains 7 participants. Two exercise groups (GCM and TA) performed OKC exercise with elastic bands twice per week for 4 weeks, while non-exercise group did nothing. We obtained the data for static and dynamic balance and muscle strength before and after the intervention. We used the Kruskal-Wallis test to compare and analyze the pre-post-intervention differences among the groups. Results: For static balance, the stability index of the TA group was the lowest for the dynamic platform (p<0.05). The dynamic balance of the TA group increased for the anterior and posteromedial directions (p<0.05). The peak torque increased in the TA group for dorsiflexion (D/F) movement and in the GCM group for plantar flexion movement compared with the other groups, except for the left direction during D/F (p<0.05). Conclusion: OKC exercises with elastic bands were effective for selectively increasing muscle strength. It is clinically thought that strength training for TA muscles will be effective among the muscles of the ankle.
LED 드라이버 설계를 위한 상용 IC의 PSPICE 모델링 기법
이윤재(Yun Jae Yi),유윤섭(Yun Seop Yu) 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6
PC817A optocoupler and TOP245P driver IC modeling technique are proposed for the LED Driver design. For PC817A modeling, the empirical equation of PC817A CTR(current transfer ration) is fitted from the datasheet of PC817A. Analog behavioral model of TOP245P IC including the shunt regulator and PWM comparator blocks is developed by using PSPICE. The results simulated by the proposed modeling technique are in good agreement with those in the datasheet. The averaged-model and switching-model are applied to the PSPICE simulation.
LED 드라이버 시뮬레이션을 위한 드라이버 IC 모델링 기법
이윤재(Yun Jae Yi),최범호(Bum Ho Choi),유윤섭(Yun Seop Yu) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7
TOP245P driver IC modeling technique are proposed for the LED Driver design. Analog behavioral model of TOP245P IC including the shunt regulator, under-voltage(UV) detection, over-voltage(OV) shut-down and SR flip-flop is developed by using PSPICE. The averaged-model and switching-model is applied to the LED driver simulation. The simulation results by the proposed TOP245P IC modeling technique are in good agreement with that in the data sheet and an experiment data.