• Journal of Korean Physical Therapy Science
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• v.28 no.2
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• pp.1-9
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• 2021

Background: The requirements for postural and motor control in backward walking training (BWT) may improve balance and walking speed in patients with acute stroke. The aim of this study was to analyze the effect of BWT on balance, balance confidence, and fall efficacy in this population. Design: Randomized controlled pilot trial. Methods: This study included 14 subjects with acute stroke (onset of illness less than one month). They were randomly allocated to a BWT (n=7) or forward walking training (n=7) group and observed five times in a week for a period of two weeks. Measurements were taken before and after the experiment using the Berg balance scale (BBS), Activities-specific balance confidence scale (ABC), and Fall efficacy scale (FES). Results: The BBS, ABC and FES scores obtained in both groups after the experiment were significantly higher than those before the experiment (p<0.05). In addition, the BBS, ABC, and FES scores in the experimental group were significantly higher than those in the control group (p<0.05). Conclusion: These findings indicate that BWT improved balance and balance confidence and decreased the risks of fall in patients with acute stroke. Further study is needed to better understand the effects of backward walking in acute stroke patients.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.148-154
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• 2005

As the exciting point of each phase is determined by the position of rotor, the rotor's accurate position-information is needed for the Switched Reluctance Motor(SRM). When using an absolute-encoder or a resolver, to detect the location of rotor the initial starting is possible, as early sensing of rotor's location is possible. However, this is not appropriate, considering the economical efficiency, and in case of using the incremental-encoder, there's a problem at initial starting as it is not easy to track down the location of rotor at the very beginning. When using Hall-ICs, there's a fault, as it needs a special ring magnet. Considering the initial starting and economical efficiency, the optical sensor technique using a slotted-disk and an opto-interrupter is appropriate, however, this method needs three opto-interrupters and a slotted-disk when using the 6/4 pole SRM. Nevertheless, in this paper, it used only two optical sensors to operate 6/4 pole SRM and made the start up and also forward and reverse operation possible. By excluding the slotted-disc md shortening a optical sensor, it improved the convenience and economical efficiency of the production. Also, as the space for slotted-disc is no more needed, it was able to reduce the size of motor.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.21-28
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• 2020

In this paper, a new type of electric wheelbarrow is proposed and developed. The developed electric wheelbarrow is equipped with an attitude reference system(ARS) sensor, which consists of 3-axis acceleration sensor and 2-axis Gyro sensor so that it can estimate pitch angle and roll angle. When an operator tilts the wheelbarrow up and down, the pitch angle is detected. The sign of the pitch angle is interpreted as the operator's intention for moving the wheelbarrow forward or backward and the controller drives the wheel of the wheelbarrow with the velocity according to the magnitude of the detected pitch angle. A cargo box of the wheelbarrow is designed to rotate and is controlled to maintain level always, so an operator can handle the electric wheelbarrow easily and safely. The wheelbarrow consists of an in-wheel motor, a DC motor, motor drives, an ARS sensor considering economical use in industrial field. Three experiments are performed to verify the feasibility and stability of the electric wheelbarrow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5305-5310
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• 2012

This study is Carpal tunnel syndrome(CTS) disorder of median nerve at wrist. It is usually diagnosed through clinical manifestation and Nerve Conduction Study(NCS). NCS of the median nerve before and after operation were compared in twenty four patient's with CTS, in order to seventeen patient's evaluate the prognostic value of that findings. Analysis result symptom profile of CTS in total number of patient's 17 (Female:17, Male:0), 21 hands (Rt:9, Lt:4, Both:4), Ages(31~60), Mean duration of symptom months($46.6{\pm}36.1$), Mean interval between 1st and 2nd NCS months($20.5{\pm}7.1$), Sensory symptoms(Tingling:21, Numbness:19, Noctunal paresthesia:17), Motor symptoms(Thenar atrophy:20, Trigger finger:2, Morning stiffness:3), Post-operative symptoms(Free:38.1%, >50% improve:52.4%, <50% improve:9.5%). NCS was normal range after operation than before in Sensory nerve conduction study 4 patients's and Motor nerve conduction study 5 patients. Surgery before and after Sensory nerve action potential (SNAP) responses showed improvement over the previous results. Forward by the patient's occupation and occupation patterns of CTS, other treatment methods and surgical treatment of CTS by comparing the degree of improvement to identify and correct nerve conduction study to judge whether the patient's operation.

• Journal of Biomedical Engineering Research
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• v.38 no.2
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• pp.74-81
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• 2017

The purpose of this study was to investigate the EMG characteristics of driver's upper extremity and driving performance for manipulating brake and accelerator pedal by using left and right hand control devices during simulated driving. The people with disabilities in the lower limb have problems in operation of the motor vehicle because of functional loss for manipulating brake and accelerator pedal. Therefore, if hand control device is used for adaptive driving controls in people with lower limb impairments, the disabled people can improve their quality of life by driving a motor vehicle. Six subjects were participated in this study to evaluate driving performance and muscle activities for operating brake and accelerator pedal by using two different hand controls (steering column mounted hand control and floor mounted hand control) in driving simulator. We measured EMG activities of six muscles (posterior deltoid, middle deltoid, triceps, biceps, flexor carpi radialis, and extensor carpi radialis) during pushing and pulling movement with different hand controls for acceleration and braking. STISim Drive 3 software was used for the performance test of different hand control devices in straight lane course for time to reach target speed and brake reaction time. While pulling the hand control lever toward the driver, normalized EMG activities of middle deltoid, triceps and flexor carpi radialis in subjects with disabilities were significantly increased (p < 0.05) compared to the normal subjects. It was also found that muscle responses of posterior deltoid were significantly increased (p < 0.05) when using the right hand control than left hand control. While pushing the hand control lever forward away from the driver, normalized EMG activities of posterior deltoid, middle deltoid and extensor carpi radialis in subjects with disability were significantly increased (p < 0.05) compared to the normal subjects. It was shown that muscle responses of middle deltoid, biceps and extensor carpi radialis were significantly increased when using the right hand control than left hand control. Brake reaction time and time to reach target speed in subjects with disability was increased by 12% and 11.3% on average compared to normal subjects. The subjects with physical disabilities showed a tendency to relatively slow acceleration at the straight lane course.

• The Journal of Internal Korean Medicine
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• v.40 no.2
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• pp.220-227
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• 2019

Objectives: Parkinson's disease is the neurodegenerative disease that affects both motor and non-motor function, including postural instability. Camptocormia is an abnormal condition in which the thoracolumbar spine bends forward during walking or standing. However, the treatment options are limited and often not effective. The purpose of this study was to report on the Korean medical treatment of a Parkinson's disease patient with postural instability who presented with camptocormia. Methods: We used Korean medical treatment including herbal medicine (Jemageopung-tang), acupuncture and pharmacopuncture therapy to the patient who was admitted to the hospital for 21 days. The clinical symptoms were assessed with the Unified Parkinson's Disease Rating Scale (UPDRS) and walking time without assistance. Results: After treatment, the UPDRS Parts 2 and 3 scores were decreased from 5 to 3 and 20 to 9, respectively. Also, the walking time without assistance was improved. Conclusion: This study suggested that Korean medical treatment could be an effective option for treating Parkinson's disease with postural instability.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.49-55
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• 2022

The role of drones has been expanded to various fields such as agriculture, construction, and logistics. In particular, agriculture drones are emerging as an effective alternative to solve the problem of labor shortage and reduce the input cost. In this study therefore, we proposed the fruit recognition algorithm and harvesting mechanism for fruit harvesting drone system that can safely harvest fruits at high positions. In the fruit recognition algorithm, we employ "You-Only-Look-Once" which is a deep learning-based object detection algorithm and verify its feasibility by establishing a virtual simulation environment. In addition, we propose the fruit harvesting mechanism which can be operated by a single driving motor. The rotational motion of the motor is converted into a linear motion by the scotch yoke, and the opened gripper moves forward, grips a fruit and rotates it for harvesting. The feasibility of the proposed mechanism is verified by performing Multi-body dynamics analysis.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.1-10
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• 2023

This paper proposes a method to extend Inter-Carrier Interference (ICI) canceling Orthogonal Frequency Division Multiplexing (OFDM) receivers for 5G mobile systems to spatial multiplexing 2×2 MIMO (Multiple Input Multiple Output) systems to support high-speed ground transportation services by linear motor cars traveling at 500 km/h. In Japan, linear-motor high-speed ground transportation service is scheduled to begin in 2027. To expand the coverage area of base stations, 5G mobile systems in high-speed moving trains will have multiple base station antennas transmitting the same downlink (DL) signal, forming an expanded cell size along the train rails. 5G terminals in a fast-moving train can cause the forward and backward antenna signals to be Doppler-shifted in opposite directions, so the receiver in the train may have trouble estimating the exact channel transfer function (CTF) for demodulation. A receiver in such high-speed train sees the transmission channel which is composed of multiple Doppler-shifted propagation paths. Then, a loss of sub-carrier orthogonality due to Doppler-spread channels causes ICI. The ICI Canceller is realized by the following three steps. First, using the Demodulation Reference Symbol (DMRS) pilot signals, it analyzes three parameters such as attenuation, relative delay, and Doppler-shift of each multi-path component. Secondly, based on the sets of three parameters, Channel Transfer Function (CTF) of sender sub-carrier number n to receiver sub-carrier number l is generated. In case of n≠l, the CTF corresponds to ICI factor. Thirdly, since ICI factor is obtained, by applying ICI reverse operation by Multi-Tap Equalizer, ICI canceling can be realized. ICI canceling performance has been simulated assuming severe channel condition such as 500 km/h, 8 path reverse Doppler Shift for QPSK, 16QAM, 64QAM and 256QAM modulations. In particular, 2×2MIMO QPSK and 16QAM modulation schemes, BER (Bit Error Rate) improvement was observed when the number of taps in the multi-tap equalizer was set to 31 or more taps, at a moving speed of 500 km/h and in an 8-pass reverse doppler shift environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.40-47
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• 2013

The similarity in internal flow of solid and hybrid rocket suggests that hybrid rocket combustion can be susceptible to instability due to vortex sheddings and their interaction. This study focuses on the evolution of interaction of vortex generated in pre-chamber with other types of vortex in the combustor and the change of combustion characteristics. Baseline and other results tested with disks show that there are five different frequency bands appeared in spectral domain. These include a frequency with thermal lag of solid fuel, vortex shedding due to obstacles such as forward, backward facing step and wall vortices near surface. The comparison of frequency behavior in the cases with disk 1 and 3 reveals that vortex shedding generated in pre-chamber can interact with other types of vortex shedding at a certain condition. The frequency of Helmholtz mode is one of candidates resulting to a resonance when it was excited by other types of oscillation even if this mode was not discernable in baseline test. This selective mechanism of resonance may explain the reason why non-linear combustion instability occurs in hybrid rocket combustion.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.534-539
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• 2008

This paper is about intelligent hexapod robot for the support walking of the aged person. The robot using various sensors and small camera has various abilities of forward backward walking, turing left or right, control the speed of walking, avoiding the obstacles and detecting risky situation of fire or gas. To let the aged feel soft and safe walking, we used special servo motor and developed hexapod walking mechanism and effective algorithm.