• 전력전자학회논문지
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• 제28권1호
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• pp.8-14
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• 2023

This paper proposes a PFC converter with a double step-up function using an asymmetrical PWM scheme. For the conventional PWM scheme, the input voltage range, which maintains a double step-up function, is limited because the proposed converter has different voltage gains and characteristics when the duty ratio(D) is less than 0.5. The proposed converter has a constant voltage gain regardless of the magnitude of the input voltage and can achieve output voltage balancing by using the asymmetrical PWM scheme. A 1.6-kW prototype of the proposed converter was built and tested to verify the performance.

• 한국전문물리치료학회지
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• 제20권4호
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• pp.40-46
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• 2013

The purpose of this study was to determine which spatiotemporal gait parameters obtained during hemiplegic walking could be a predictive factor for the Timed Up and Go test (TUG). Two hundreds nine subjects who had suffered a stroke were recruited for this study. They were participated in two assessments; the TUG test and gait analysis. The relationship between the TUG test and spatiotemporal parameters was analyzed using Pearson's correlation coefficients. In addition, to predict the spatiotemporal gait parameters that correlated most with the TUG scores, we used multiple linear regression analyses (stepwise method). The results show that the normalized velocity was strongly correlated with the TUG performance (r=-.72, p<.001). Additionally, single support percentage (SSP), double support percentage (DSP), step time difference (STD), and step length difference (SLD) significantly were correlated with the TUG test. Normalized velocity, STD, DSP of affected side, and SSP of non-affected side explained 53%, 8%, 3%, 2%, of variance in the TUG test respectively. In conclusion, an increase in gait velocity and a decrease in STD would be effective indicators of improvement on the functional mobility in the stroke rehabilitation.

• Physical Therapy Rehabilitation Science
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• 제2권1호
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• pp.39-43
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• 2013

Objective: The objective of this study is to investigate the effect of treadmill gait trainig on dynamic balance and gait functions in stroke patients. Design: Randomized, double-blind, controlled pilot study. Methods: Four subjects following first stroke participated in this study. They were divided randomly into the treadmill gait trainig group (TM group) (n=2) and the control group (n=2). Subjects in both groups received general training five times per week. Subjects in the TM group practiced an additional treadmill gait trainig program that consisted of 60 minutes, three times per week, during a period of four weeks. Timed up and go test (dynamic balance) and the GAITRite test (gait function) were evaluated before and after the intervention. Results: In dynamic balance (timed up and go test), the TM group (-14.235 sec) showed a greater decrease than the control group (-13.585 sec). In gait functions, the TM group showed a greater increase in gait speed (12.8 cm/s vs. 10.15 cm/s), step-length (5.825 cm vs. 3.735 cm), and stride-length (5.005 cm vs. 1.55 cm) than the control group. Conclusions: The treadmill gait trainig improved dynamic balance and gait functions. Further research is needed in order to confirm the generalization of these findings and to identify which stroke patients might benefit from treadmill gait trainig.

• 재활복지공학회논문지
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• 제10권4호
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• pp.251-257
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• 2016

소아균형검사(Pediatric Balance Scale)는 경증이나 중증의 운동손상을 지닌 학령기 아동에게 사용할 수 있는 균형검사도구이다. 본 연구의 목적은 경직성 양하지 뇌성마비 아동을 대상으로 소아균형검사와 시공간적 보행변수간의 상관관계를 알아보고자 하였다. 소아균형검사는 앉은 자세에서 일어나기, 선 자세에서 앉기, 의자에서 의자로 이동하기, 잡지 않고 서 있기, 한 다리로 서 있기, 제자리에서 $360^{\circ}$ 회전하기, 뒤돌아보기 등 총 14개 항목으로 구성하고, 시공간적 보행변수는 보행속도 및 보폭, 보거리, 보격, 분속수, 양하지 지지 시간을 포함한다. 모든 대상자들은 독립적으로 보행이 가능한 경직성 양하지 뇌성마비 아동이며, 숙련된 소아물리치료사에 의해 소아균형검사와 시공간적 보행변수를 측정하였다. 소아균형검사와 시공간적 보행변수 간의 상관관계를 분석하기 위해 피어슨 상관분석을 사용하였고, 통계학적 유의수준은 0.05로 설정하였다. 소아균형검사의 총점(r=.49~.58)과 세부항목 중 선 자세에서 앉기(r=.48~.60)와 선 자세에서 왼쪽/오른쪽 어깨 뒤로 돌아보기(r=.47~.53), 선 자세에서 바닥에 물건 집어 들기(r=.52~.69)는 보행속도와 보폭, 보거리, 분속수의 각 변수 사이에 모두 유의한 양의 상관관계를 보였으며, 소아균형검사의 대부분 항목이 양하지 지지 시간 간의 매우 높은 음의 상관관계(r=-.48~-.92)를 보여주고 있다. 이는 소아균형검사와 시공간적 보행변수는 높은 상관관계를 가진 것을 관찰 할 수 있었으며, 소아균형검사를 통해 뇌성마비 아동의 보행수준을 예견하는데 유용하게 적용될 것이다.

• 대한골관절종양학회지
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• 제3권1호
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• pp.18-25
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• 1997

Prosthetic replacement is one of the most common methods of reconstruction after resection of malignant tumor around the knee. Gait analysis provides a relative objective data about the gait function of patients with prosthesis. The purpose of this study was to compare the gait pattern of the patients who underwent limb salvage surgery with prosthesis for distal femur and that of patients with prosthesis for proximal tibia. This study included ten patients (4 males, 6 females, mean age 22.7 years, range 14-36) who underwent a wide resection and Kotz hinged modular reconstruction prosthesis replacement and six normal adult(Control). The site of bone tumor was the distal femur (Group 1) in six patients and proximal tibia (Group 2) in 4 patients. The follow-up period ranged from 15 to 82 months (mean : 33 months). The evaluation consisted of clinical assessment, radiographic assessment, gait analysis using VICON 370 Motion Analysis System. The gait analysis included the linear parameters such as, walking velocity, cadence, step length, stride length, stance time, swing time, single support and double support time and the three-dimensional kinematics (joint rotation angle, velocity of joint rotation) of ankle, knee, hip and pelvis in sagittal, coronal and transverse plane. For the kinetic evaluation, the moment of force (unit: Nm/kg) and power (unit: Watt/kg) of ankle, knee and hip joint in sagittal, coronal and transverse plane. In the linear parameters, cadence, velocity, step time and single support were decreased in both group 1 and group 2 compared with control. Double support decreased in group 2 compared with control significantly(p<.05). In contrast to our hypothesis, there was no significant difference between group 1 and group 2. In Kinematics, we observed significant difference (p<.05) of decreased knee flexion in loading response (G2

• The Journal of Korean Physical Therapy
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• 제27권5호
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• pp.364-368
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• 2015

Purpose: Walking in the dual-task condition is a critical skill for hemiplegic patients to live in real-life situations. The purpose of this study was to compare the effect of dual-task gait training and general gait training on gait parameters and cognitive function in patients with chronic stroke during dual-task walking. Methods: The study included 23 patients with chronic hemiparetic stroke who were randomly divided into experimental (dual-task gait training) and control (general walking training) groups. The 11 subjects in the experimental group and nine subjects in the control group received dual-task gait training (walking while handling a ball, crossing obstacles, picking up various objects, and problem solving simple cognitive tasks and general over-ground gait training, respectively, for 30 minutes per day 5 days per week for 4 weeks. Spatiotemporal parameters and cognitive tasks in the dual-task gait condition were measured. Statistical analysis of the changes between the pre- and post-intervention measurement variables was performed using ANCOVA. Results: In the gait condition under cognitive tasks, the changes pre- and post-intervention in gait velocity, stride length, double support limb, and step symmetry were significantly greater in the dual-task gait training group; however, the dual-task gait training group showed no significant improvement compared to the general gait training group in terms of the assessment of cognitive tasks. Conclusion: The findings suggest that dual-task gait training may be beneficial for walking ability in dual-task walking condition.

• 센서학회지
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• 제14권4호
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• pp.272-277
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• 2005

A CMOS active pixel sensor has been designed and fabricated using standard 2-poly and 4-metal $0.35{\mu}m$ CMOS processing technology. The CMOS active pixel sensor has been made up of a unit pixel having a highly sensitive PMOSFET photo-detector and electronic shutters that can control the light exposure time to the PMOSFET photo-detector, correlated-double sampling (CDS) circuits, and an 8-bit two-step flash analog to digital converter (ADC) for digital output. This sensor can obtain a stable photo signal in a wide range of light intensity. It can be realized with a special function of an electronic shutter which controls the light exposure-time in the pixel. Moreover, this sensor had obtained the digital output using an embedded ADC for the system integration. The designed and fabricated image sensor has been implemented as a $128{\times}128$ pixel array. The area of the unit pixel is $7.60{\mu}m{\times}7.85{\mu}m$ and its fill factor is about 35 %.