• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.435-441
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• 2006

The anterior cruciate ligament(ACL) is an important stabilizer of knee joint. The ACL injury of knee is common and a serious ACL injury leads to ligament reconstruction surgery. Gait analysis is essential to identify knee condition of patients who display abnormal gait. The purpose of this study is to evaluate and classify knee condition of ACL deficient patients using a nonlinear dynamic method. The nonlinear method focuses on understanding how variations in the gait pattern change over time. The experiments were carried out for 17 subjects(l2 healthy subjects and five subjects with unilateral deficiency) walking on a motorized treadmill for 100 seconds. Three dimensional kinematics of the lower extremity were collected by using four cameras and KWON 3D motion analysis system. The largest Lyapunov exponent calculated from knee joint flexion-extension time series was used to quantify knee stability. The results revealed the difference between healthy subjects and patients. The deficient knee was significantly unstable compared with the contralateral knee. This study suggests an evaluation scheme of the severity of injury and the level of recovery. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• The Journal of Korean Physical Therapy
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• v.24 no.5
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• pp.306-312
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• 2012

Purpose: The purpose of this study was to examine the effect of changes in foot cutaneous sensation on plantar pressure distribution during gait. Methods: Sixteen healthy young subjects participated in this experiment. All subjects performed two trials of walking under three somatosensory conditions induced by a normal facilitatory insole that provides increased plantar sensory stimulation, and application of lidocaine cream to the plantar surface of the foot to reduce the sensitivity of the soles. Semmes-Weinstein monofilaments were used for evaluation of reduced plantar sensation. The Pedar system was used for measurement of pressure distribution at the plantar surface of the foot. Results: Pressure in the lateral midfoot area showed an increase with increasing and decreasing sensory inputs. When sensory input was increased, plantar pressure showed a decrease in the forefoot area. When sensory input was decreased, plantar pressure showed an increase in the lateral forefoot area and a decrease in the hallux area. Conclusion: By altering sensory feedback, plantar pressure distribution is changed during gait. Plantar cutaneous afferents play an important role in plantar distribution.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.672-678
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• 2008

This paper proposes a new rehabilitation robot with upper and lower limb connections for gait training. As humans change a walking speed, their nervous systems adapt muscle activation patterns to modify arm swing for the appropriate frequency. By analyzing this property, we can find a relation between arm swinging and lower limb motions. Thus, the lower limb motion can be controlled by the arm swing for walking speed adaptation according to a patent's intension. This paper deals with the design aspects of the suggested gait rehabilitation robot, including a trajectory planning and a control strategy. The suggested robot is mainly composed of upper limb and lower limb devices, a body support system. The lower limb device consists of a slider device and two 2-dof footpads to allow walking training at uneven and various terrains. The upper limb device consists of an arm swing handle and switches to use as a user input device for walking. The body support system will partially support a patient's weight to allow the upper limb motions. Finally, we showed simulation results for the designed trajectory and controller using a dynamic simulation tool.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.261-266
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• 2010

Human body is hard to be in perfect balance during walking. Most of time the trunk is supported by one leg and the center of mass(COM) falls to the contralateral side. Thus, dynamic variables such as the velocity of the COM should be considered when gait stability is evaluated. The purpose of this study was to investigate whether the extrapolated center of mass(XCom) which utilized the COM position and its velocity, is appropriate to evaluate gait stability. Ten healthy adults participated in this study and performed 3 different types of gaits(normal(NG), hands on waists(HWG), and hands on shoulders(HSG)) onto 4 different types of obstacle(obstacle height: 0%, 30%, 40% and 50% of leg length). Medio-lateral Com-CoP and XCom-CoP inclination angle were calculated during support phase. For all condition, greater M-L XCoM-CoP inclination angles were found(p<.05) compared with those of matched obstacle height CoM-CoP. Especially, M-L XCoM-CoP inclination angle at 50% height revealed the best condition for monitoring dynamic stability. Significantly increased in M-L XCoM-CoP inclination angle was found(p<.05) as obstacle height increased on NG and HWG.

• Korean Journal of Acupuncture
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• v.19 no.2
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• pp.79-85
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• 2002

Objective : In 1983 Autosomal dominent spinocerebellar ataxia(ADCA) has been classified to four types by a useful clinical features according to Harding. Since 1993 ADCA referred to as SCA by molecular genetic characteristics. We focused on the improvement of clinical symptoms in SCA patient through oriental medical treatment. Methods ＆ Results : The assessment included neurophysiological examination and clinical symptoms. For example slow saccade, gaze limitation, upward and lateral, nystagmus, truncal and gait ataxia. The patient(M/30) was clinically charaterized by ocular abnormalities, trunkal and gait ataxia and the MRI showed atrophy of cerebellar vermis. The patient was taken both common acupuncture and Dong-Si venepuncture on Hwasan with herbal medicine. Before the treatment Rt. ocular movement were slowed and a significant eye fixation was observed always in abduction and intermittently presented trunkal and gait ataxia. During the treatment trunkal and gait ataxia has not been presented and ocular obnomalities changed to normal state. This case suggests the possibility of oriental medical treatment on SCA but further observation is needed on this patient.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.71-77
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• 2019

Objective: The aim of this study was to investigate postural control strategies on smart phone use during gait in over 50-year-old adults. Method: 8 elderly subjects (age: $55.5{\pm}3.29yrs$, height: $159.75{\pm}4.20cm$, weight: $62.87{\pm}8.44kg$) and 10 young subjects (age: $23.8{\pm}3.19yrs$, height: $158.8{\pm}5.97cm$, weight: $53.6{\pm}5.6kg$) participated in the study. They walked at a comfortable pace in a gaitway of ~8 m while: 1) reading text on a smart phone, 2) typing text on a smart phone, or 3) walking without the use of a phone. Gait parameters and kinematic data were evaluated using a three-dimensional movement analysis system. Results: The participants read or wrote text messages they walked with: slower speed; lesser stride length and step width; greater flexion range of motion of the head; more flexion of the thorax in comparison with normal walking. Conclusion: Texting or reading message on a smart phone while walking may pose an additional risk to pedestrians' safety.

• PNF and Movement
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• v.20 no.1
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• pp.59-66
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• 2022

Purpose: The aim of this research was to verify the relationship between three-dimensional (3D) ground reaction force (GRF) and severity of leg length discrepancy (LLD) while walking at a normal speed. It used a 3D motion analysis system with force platforms in standing workers with LLD. Methods: Subjects comprising 45 standing workers with LLD were selected. Two force platforms were used to acquire 3D GRF data based on a motion analysis system during gait. Vicon Nexus and Visual3D v6 Professional software were used to analyze kinetic GRF data. The subjects were asked to walk on a walkway with 40 infrared reflective markers attached to their lower extremities to collect 3D GRF data. Results: The results indicated the maximal force in the posterior and lateral direction of the long limb occurring in the early stance phase during gait had significant positive correlation with LLD severity (r = 0.664~0.738, p <0.01). In addition, the maximal force medial direction of the long limb occurring in the late stance phase showed a highly positive correlation with the LLD measurement (r = 0.527, p <0.01). Conclusion: Our results indicate that greater measured LLD severity results in more plantar pressure occurring in the foot area during heel contact to loading response of the stance phase and the stance push-off period during gait.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.109-119
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• 2017

In the present study, to determine walking imbalance using the walking analysis method, where limitations in the existing walking analysis have been minimized, we propose a new walking analysis method that adopts the following: self-developed equipment to measure the angles of left-right hip joints and knee joints; a determination system using symmetry index (SI); and dynamic time warping (DTW) similarity analysis algorithm to analyze individual walking styles. Normal and imbalanced walking tests were conducted for 12 subjects without walking disorder. From the SI calculation to determine imbalanced walking, both the normal and imbalanced walking styles can be determined using the angle measurements of the left-right hip joints and knee joints. In the analysis of the individual walking styles, the similarities at the center of the lower back, left-right thighs, and dorsum of the feet of the 12 subjects in both normal and imbalanced walking cases were compared. From the similarity analysis of the measured values during the normal and imbalanced walking tests, I determined that the walking pattern does not maintain the same stance when the body parts move during walking.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.10
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• pp.879-883
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• 2015

Conventional gait rehabilitation requires at least three therapists in a traditional rehabilitation training program. Several robots have been developed to reduce human burden and increase rehabilitation efficacy. In this study, we present a lower-limb wearable robot (WA-H) for gait rehabilitation of hemiplegia patients, and propose a protocol of 12 weeks gait rehabilitation training program using WA-H. To identify the efficacy of the robot and protocols, we conducted a clinical study with two actual hemiplegia patients and observed a chronological change of ambulation ability through four assessments. We discovered the progression of results by 6 minute walking test, TUGT (Timed Up and Go Test), SPPB (Short Physical Performance Battery), BBS (Berg Balance Test), and Fugl-Meyer score. The torques generated in the normal side and paralyzed side of the patient became similar, indicating rehabilitation. The result also showed the walking of the paralysis patient improved and imbalance motion had considerable improved performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.24-24
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• 2003

For the elderly, achieving a close-to-normal ambulation is important for activities of daily life. Recent researches of SE(Silver Engineering) restoring physical ability would help the elderly by developing the advanced gait assisting devices and orthoses. For the applications using the advanced technologies, the gait characteristics of the elderly must be understood. However, a few studies were performed to investigate the physiological or pathological gaits. The purpose of this study is to provide the gait analysis data and also to investigate relationships between alignment of the lower limb, foot progression angle and knee joint moments in the healthy elderly. By participating a total of 20 healthy elderly persons in this study, the following facts were found: 1) Cadence showed 114.8 steps/min, gait speed showed 1.05 m/s, time per a stride showed 1.06 sec, time per a step showed 0.53 sec, single-supporting phase was 0.41 sec, double-supporting phase was 0.24 sec, stride length was 1.04m, Step length was 0.56m; 2) The maximum knee flexion angle through swing phase showed left 46.82$^{\circ}$, right 40.19$^{\circ}$ and the maximum knee extension angle showed left -1.32$^{\circ}$, right 2.01$^{\circ}$. Knee varus showed left 26.90$^{\circ}$, right 30.93$^{\circ}$; 3) The maximum knee flexion moment showed left 0.363 Nm/kg, right 0.464 Nm/kg, The maximum knee extension moment showed left 0.389 Nm/kg, right 0.463 Nm/kg. The maximum knee adduction moment showed left 0.332 Nm/kg, right 0.379 Nm/kg. The maximum internal rotational moment showed left 0.13 Nm/kg, right 0.140 Nm/kg; 4) The subjects who had varus alignment of the lower extremity had statistically higher in knee adduction moment in mid stance phase; and 5) The subjects who had large foot progression angle had statistically lower in knee adduction moment in late stance phase.