• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.196-203
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• 2004

In this study, a new gait phase detection system using both FSR(Force Sensing Resister) sensors and a gyrosensor was developed to detect various gait patterns. FSR sensors were put in self-designed shoe insoles and a gyrosensor was attached to the posterior aspect of a shoe. An algorithm was also developed to determine eight different gait transitions among four gait phases: heel-strike, foot-flat, heel-off and swing. The developed system was compared with the conventional gait phase detection system using only FSR sensors in various gait experiments such as level walking, fore-foot walking and stair walking. In fore-foot walking and stair walking, the developed system showed much better accuracy and reliability to detect gait phases. The developed gait phase detection system using both FSR sensors and a gyrosensor will be helpful not only to determine pathological gait phases but to apply prosthetics, orthotics and functional electrical stimulation to patients with gait disorders.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.30-33
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• 2008

Understanding the characteristics of amputee gait is key in developing more advanced prostheses. The aim of this study was to quantitatively analyze a stair-climbing task for transfemoral amputees with a prosthesis and to predict the muscle forces and joint moments at musculoskeletal joints using a dynamic analysis. A three-dimensional musculoskeletal model of the lower extremities was constructed from a gait analysis using transformation software for two transfemoral amputees and ten healthy people. The measured ground reaction forces and kinematical data of each joint from the gait analysis were used as input data for an inverse dynamic analysis. Dynamic analyses of an transfemoral amputee climbing stairs were performed using musculoskeletal models. The results showed that the summed muscle forces of the hip extensor of an amputated leg were greater than those of a sound leg. The opposite was true at the hip abductor and knee flexor of an amputated leg. We also found that higher moments at the hip and knee joints of the sound leg were required to overcome the flexion moment caused by the body weight and amputated leg. Dynamic analyses using musculoskeletal models may be a useful means to predict muscle forces and joint moments for specific motion tasks related to rehabilitation therapy.

• Fire Science and Engineering
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• v.25 no.5
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• pp.14-20
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• 2011

As the height of the building increases, the stack effect in stairwell that is main facilities for evacuation becomes stronger. While the pressure rise in stairwell causes difficulties on opening the door for evacuation and has effect on smoke control system, reduction of stack effect will be necessary for providing more safe evacuation environment. The field experiments on pressure field in high-rise building are carried out to present reduction method of stack effect and the numerical analyses using network model are proceeded to design quantitatively the reduction method. As the air flow supplied from outside in lower stair and exhausted to outside in upper stair is formed in stairwell, the stack effect in stairwell is expected to be decreased.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1364-1370
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• 2002

The objective of this study was to examine the effect of compensatory growth nutritional regimen on mammary gland growth and lactation. One hundred twenty-two Sprague Dawley female rats (35 days of age) were randomly assigned to either a control or a stair-step compensatory nutrition (SSCN) feeding regimen or an alternating 2-2-3-3-week schedule beginning with 40% energy restriction for 2 weeks followed by re-alimentation (control diet) for 2 weeks. Pup weight gain and milk yield were improved 8% and 8 to 15%, respectively, by the SSCN regimen. The gene expression of $\beta$-casein was 2.3-fold greater in the SSCN group than in the control group during early lactation, but they were greater at all stages of the second lactation. The gene expression of insulin-like growth factor-I was 40% lower in the SSCN group than in the control group during early lactation of the second lactation, but during late lactation it was 80% greater than in the control group. The concentration of serum corticosterone tended to be higher in the SSCN group during the late stage of the first lactation. These results suggest that the stair-step compensatory nutrition regimen improves lactation performance and persistency by modulation of cell differentiation and apoptotic cell death.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.117-123
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• 2011

The low electric power and high efficiency chips are required because of the appearance of smart phones. Also, high-capacity memory chips are needed. e-MMC(embedded Multi-Media Card) for this is defined by JEDEC(Joint Electron Device Engineering Council). The e-MMC memory for research and development is a memory mulit-chip module of 64GB using 16-multilayers of 4GB NAND-flash memory. And it has simplified the chip by using SIP technique. But mulit-chip module generates high heat by higher integration. According to the result of study, whenever semiconductor chip is about 10 $^{\circ}C$ higher than the design temperature it makes the life of the chip shorten more than 50%. Therefore, it is required that we solve the problem of heating value and make the efficiency of e-MMC improved. In this study, geometry of 16-multilayered structure is compared the temperature distribution of four different geometries along the numerical analysis. As a result, it is con finned that a multilayer structure of stair type is more efficient than a multilayer structure of vertical type because a multi-layer structure of stair type is about 9 $^{\circ}C$ lower than a multilayer structure of vertical type.

• The Journal of Korean Physical Therapy
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• v.24 no.4
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• pp.247-252
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• 2012

Purpose: The purpose of this study was to investigate the change of muscle activities during level walking, stairs and ramp climbing in hemiplegic patients. Methods: Eight hemiplegic patients were recruited and agreed to participate in this study. Muscle activity was measured by MP100 system (BIOPAC System Inc., Santa Barbara, CA, USA). Statistical analysis was used as a one-way repeated measure of ANOVA to know the difference according to the gait conditions (level walking, stairs and ramp ascending). Results: In the swing phase, muscle activity of rectus femoris muscle, with the side lower extremities affected, were generally significantly different in the stair and ramp ascending. In addition, biceps femoris muscle with unaffected side lower extremity was generally significantly different in the ramp ascending. In the swing phase, muscle activity of tibialis anterior muscle with unaffected side lower extremities was generally showed a significant difference in the ramp ascending. In the stance phase, climbing stairs and ramps showed an increase in the muscle activities. Further, climbing the stairs increased muscle activities of the gastrocnemius muscle. Conclusion: These findings indicate that compared with the level walking climbing stairs, ramps and muscle activities of lower extremity during each showed different results. It can be seen that in accordance with the terms of gait are different muscles group recruitment.

• Journal of Biomedical Engineering Research
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• v.26 no.3
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• pp.145-150
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• 2005

A new gait detection system using both FSR (force sensing resistor) sensors and a gyrosensor was developed to detect various gait patterns. FSR sensors were put in self-designed shoe insoles and a gyrosensor was attached to the heel of a shoe. An algorithm was also developed to determine eight different gait transitions during four gait phases: heel-strike, foot-flat, heel-off and swing. The developed system was evaluated from nine heathy mans and twelve hemiplegic patients. Healthy volunteers were asked to walk in various gait patterns: level walking, fore-foot walking and stair walking. Only the level walking was performed in hemiplegic patients. The gait detection system was compared with a optical motion analysis system and the outputs of the FSR sensors. In healthy subjects, the developed system detected successfully more than $99\%$ for both level walking and fore-foot walking. For stair walking, the successful detection rate of the system was above$97\%$. In hemiplegic patients, the developed system detected approximately 98% of gait transitions. The developed gait phase detection system will be helpful not only to determine pathological gait phases but also to apply prosthetics, orthotics and functional electrical stimulation for patients with various gait disorders.

• Nuclear Engineering and Technology
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• v.27 no.5
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• pp.661-669
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• 1995

A mobile robot, named KAEROT, has been developed for inspection and maintenance operations in nuclear facilities. The main feature of locomotion system is the planetary wheel assembly with small wheels. This mechanism has been designed to be able to go over the stairs and obstacles with stability. This paper presents the inverse kinematic solution that is to be operated by remote control. The automatic stair climbing algorithm is also proposed. The. proposed algorithms generates the moving pathes of small wheels and calculates the angular velocity of 3 actuation wheels. The results of simulations and experiments are given for KAEROT peformed on the irregular stairs in laboratory. It is shown that the proposed algorithm provides the lower inclination angle of the robot body and increases its stability during navigation.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.3
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• pp.189-196
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• 2021

In this paper, we propose techniques to correct the altitude error and heading error of 3D Pedestrian Inertial Navigation (PIN). When a PIN is used to estimate the location of a pedestrian only with an Inetrial Measurement Unit (IMU) without infrastructure, there is a problem in that the location error gradually increases due to the limitation of the observability of the filter. To solve this problem without additional sensors, we propose two techniques in this paper. First, stair walking is recognized in consideration of the altitude difference that may occur during one step. If it is recognized as stair walking, only Zero-velocity UPdaTe (ZUPT) is performed, and if it is recognized as level walking, ZUPT + Altitude Damping (AD) is performed together to correct the altitude error. Second, the straight-line movement direction is calculated through the difference of the estimated position, and the heading error is corrected by matching this information with the link information of the digital map. By applying these techniques, it is verified through real tests that accurate three-dimensional location information of pedestrians can be estimated without infrastructure.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.121-125
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• 2022

This paper deals with the development of a deep-learning-based robot that recognizes various types of stairs and performs a mission to go up to the target floor. The overall motion sequence of the robot is performed based on the ROS robot operating system, and it is possible to detect the shape of the stairs required to implement the motion sequence through rapid object recognition through YOLOv4 and Cuda acceleration calculations. Using the ROS operating system installed in Jetson Nano, a system was built to support communication between Arduino DUE and OpenCM 9.04 with heterogeneous hardware and to control the movement of the robot by aligning the received sensors and data. In addition, the web server for robot control was manufactured as ROS web server, and flow chart and basic ROS communication were designed to enable control through computer and smartphone through message passing.