• Tribology and Lubricants
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• v.37 no.2
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• pp.48-53
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• 2021

Wind energy is considered as the most competitive energy source in terms of power generation cost and efficiency. The power train of the pitch drive for a wind turbine uses a 3-stage complex planetary gear system in being developed locally. A gear train of the pitch drive consists of an electric or hydraulic motor and a planetary decelerator, which optimizes the pitch angle of the blade for wind generators in response to the change in wind speed. However, it is prone to many problems, such as excessive repair costs in case of failure. Complex planetary gears are very important parts of a pitch drive system because of strength problem. When gears are designed for the power train of a pitch drive, it is necessary to analyze the fatigue strength of gears. While calculating the specifications of the complex planetary gears along with the bending and compressive stresses of the gears, it is necessary to analyze the fatigue strength of gears to obtain an optimal design of the complex planetary gears in terms of cost and reliability. In this study, the specifications of planetary gears are calculated using a self-developed gear design program. The actual gear bending and compressive stresses of the planetary gear system were analyzed using the Lewes and Hertz equation. Additionally, the calculated specifications of the complex planetary gears were verified by evaluating the results from the Stress - No. of cycles curves of gears.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.26-33
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• 2020

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

• PNF and Movement
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• v.12 no.2
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• pp.107-113
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• 2014

Purpose: The objective of this study was to identify functional problems, including walking ability, of patients with strokes using the International Classification of Functioning, Disability, and Health (ICF) and to present a method that could solve functional problems, thereby determining the applicability of the ICF to increase the quality of evaluation and intervention in clinical fields in the future. Methods: Information on stroke patients who were admitted and treated in a hospital was collected. The authors conducted evaluations, interventions, and measurements of the results of the ICF tool in order to improve gait abilities of patients. The subjects were trained using proprioceptive neuromuscular facilitation (PNF) one hour a day and five times a week for four weeks. The result measurement variables were a six-minute gait test, 10 m velocity test, gait instability test, and measurements using the ICF sheet. Results: In the six-minute gait test, gait distance increased by 48 m, from 102 m to 150 m. The gait velocity test result showed an improvement from 0.36m/s to 0.44m/s. The subjects performed a gait instabilitytestwithacupfilledwith50mmwater. In the gait instability test, the amount of water was 38 mm before the intervention; however, it was 50 mm after the intervention. The gait velocity with a cup filled with water improved from 0.25m/s to 0.31m/s. Conclusion: An evaluation and intervention were designed with the ICF tool for stroke patients. Gait abilities improved when the PNF technique was used. The IFC method can be used for evaluation and intervention, and it could help improve gait abilities of stroke patients.

• Journal of Family Relations
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• v.21 no.3
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• pp.3-23
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• 2016

Objectives: The purpose of this study is to examine the effects of symptoms of dementia elderly on the primary caregiver's depression. In addition, moderating effect of family support was examined. Based on the results, the necessity for intervention in the level of social welfare as a way to mitigate primary caregiver's depression was suggested. Method: In order to accomplish these purposes, a total of 197 who are spouse and adult-children of dementia elderly using day care facilities or services in Seoul, Gyeonggi, Busan province, South Korea were utilized. Data were analyzed by frequency analysis and descriptive statistics, regression model analysis with SPSS 18.0. Results: In case of analysis results, the mean value was reported 0.9 out of four point about primary caregiver's depression and the mean value of family support was reported 3.34 out of five point. And besides, the analysis result of dementia elderly's symptoms showed that prevalence of depression/dysphoria were 62.2%, prevalence of aberrant motor were 61.3%, prevalence of apathy/indifference were 56.6%. Crucial findings are as follows: the symptoms of dementia elderly was significantly associated with the primary caregiver's depression. At the same time, family support significantly influenced lower level of the primary caregiver's depression. While, in the relationship between the symptoms of dementia elderly and the primary caregiver's depression, family support has a moderation effect by important protection factor. Conclusions: From these findings, the necessities to provide the care service for dementia elderly to help improve symptoms of dementia as well as the policy and service to manage the mental health of the family as primary caregiver were suggested. Also, the necessities to provide the family therapy program to improve the relationship with family members were suggested.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.235-244
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• 2022

Objective: The aim of this study was to investigate of the foot plantar pressure and usability after gait training using the ExoAtlet wearable exoskeleton robot in an incomplete spinal cord injury (SCI) patient. Design: A case study Methods: Six participants with an asymmetry in motor and sensory function completed the gait training using ExoAtlet wearable exoskeleton robot for 15 sessions, five per weeks, 3weeks. They were divided into two groups (low and high strength group) and group differences were evaluated about session at stating of gait, gait distance at final session and foot plantar pressures and useability after training. Results: Low strength group was faster than high strength group on adaptation of robot gait. And high strength group increased faster than low strength group on the gait distance during training. In standing and gait, weaker leg was higher than stronger leg on mean foot plantar pressure in low strength group. And stronger leg was higher than weaker leg on foot plantar pressure in high strength group. The length of the anterior-posterior trajectory of the center of pressure during gait was similar in low strength group, but different in high strength group. useability was positive about ExoAtlet wearable exoskeleton gait after training. Conclusions: ExoAtlet wearable exoskeleton robot gait training was positive about improving gait in all participants regardless of differences in severity of symptoms and gait abnormalities.

• Journal of Veterinary Clinics
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• v.39 no.5
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• pp.235-239
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• 2022

A 10-year-old neutered male Siberian Husky presented with paraparesis and severe lethargy. On physical examination, the patient was unable to weight-bear and walk and exhibited significant muscle mass loss in both hindlimbs and generalized truncal alopecia with a dull coat of hair. On neurological examination, cranial lumbar vertebral pain, hind limb cross-extensor reflex, delayed hindlimb postural reaction, upper motor neuron bladder dysfunction, and total absence of cutaneous trunci reflex were identified. Computed tomography revealed diffuse idiopathic skeletal hyperostosis and spondylosis deformans of the cervical and thoracolumbar vertebrae. In addition, a generalized decrease in bone mineral density of the vertebrae was identified. Magnetic resonance imaging showed hyperplasia of the epidural fat compressing the spinal cord in the thoracolumbar region and concurrent mild multiple intervertebral disc herniations. No specific findings were observed in cerebrospinal fluid analysis. Blood analysis of thyroid function revealed decreased total T4 and free T4 levels, and increased TSH levels. The patient was tentatively diagnosed with spinal epidural lipomatosis (SEL) secondary to hypothyroidism. The patient was treated with levothyroxine, firocoxib, and gabapentin. Clinical signs gradually improved, and the patient showed normal ambulation 40 days after treatment initiation. SEL is extremely rare in dogs. To the best of our knowledge, this is the first case report of SEL secondary to hypothyroidism that was treated conservatively. Secondary SEL can be sufficiently managed by treating the underlying cause, if possible.

• Clinical Pain
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• v.19 no.2
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• pp.116-119
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• 2020

Cervical transforaminal epidural steroid injection (TFESI) is commonly performed to provide relief of pain caused by radiculopathy. Intra-arterial injection of particulate steroid or direct needle injury can lead to spinal artery embolism or thrombosis. Also there is a possibility of vascular spasm. To our knowledge, this is the first reported case of spinal cord infarction that occurred after TFESI with non-particulate steroid in Korea. A 47-year-old female patient underwent C7 TFESI at local pain clinic. Injected materials were dexamethasone and mepivacaine. Right after the intervention, she felt muscle weakness and decreased sensation. On physical examination, she had decreased sensation from C4 to T2 dermatome in light touch and pin-prick test. Proprioception and vibration were intact. The motor grades of upper extremities were grade 1. Cervical and thoracic spine MRI was checked. Diffusion-weighted image and apparent diffusion coefficient image showed long extension of spinal cord infarction from C2 to T1 level.

• Journal of Biomedical Engineering Research
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• v.44 no.2
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• pp.157-165
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• 2023

The purpose of this study was to evaluate the importance of developing slim seats with ergonomic design to improve seat comfort and expand the interior space. Two seats were used for the experiment: a sample seat designed based on hip shape and spinal alignment and a normal seat with a flat design without curves. Subjects sat in both the sample seat and a normal seat applied to the vehicle simulator and the experiment was conducted. The next part of the experiment was conducted in two different postures: a driving posture and a relaxed posture. The subjects filled out a comfort questionnaire immediately after sitting and after 30 minutes. The results showed that the comfort in the sample seat was found to be more comfortable than the normal seat. However, no significant difference was noted for the relaxation posture. Pressure distribution was also recorded immediately after sitting and after 30 minutes. In the case of pressure distribution, it was confirmed that the pressure in the sample seat was more evenly distributed in both the driving and relaxed postures than in the normal seat. The results showed that the ergonomically designed sample seat greatly improved seating comfort and pressure distribution compared to the normal seat, which is a general vehicle seat design.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.251-259
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• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• Journal of Technology Innovation
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• v.31 no.2
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• pp.263-301
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• 2023

This study analyzes whether the network characteristics lead to differences in innovation performance between inventors, using the case of Samsung Electronics and Hyundai Motor Company which have applied for the most patents in the electronics and automobile industries while showing significant differences in the degree of collaborative invention. The more inventors an inventor is connected with in the network, the higher innovation performance is achieved. While existing literature addressed intra- / interindustry, and intra- / inter- group spillovers at the organizational level, this study extends this discussion to the inventor level. This study newly introduces spillover pools from network components and then constructs spillover pools in three dimensions of the group, the industry, and the network component. The study analyzes the effects of each spillover pool on invention performance of an individual inventor and compares the effects between spillover pools. At the inventor level, the innovative effects of spillover pools were confirmed. The results of this study suggest that the inventor's network characteristics and spillover pools can be used to predict the inventor's innovation performance.