• ETRI Journal
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• v.40 no.4
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• pp.522-530
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• 2018

In this study, we developed a robotic walker that actively controls its speed and direction of movement according to the user's gait intention. Sensor fusion between a low-cost light detection and ranging (LiDAR) sensor and inertia measurement units (IMUs) helps determine the user's gait intention. The LiDAR determines the walking direction by detecting both knees, and the IMUs attached on each foot obtain the angular rate of the gait. The user's gait intention is given as the directional angle and the speed of movement. The two motors in the robotic walker are controlled with these two variables, which represent the user's gait intention. The estimated direction angle is verified by comparison with a Kinect sensor that detects the centroid trajectory of both the user's feet. We validated the robotic walker with an experiment by controlling it using the estimated gait intention.

• Animal Systematics, Evolution and Diversity
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• v.15 no.2
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• pp.205-220
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• 1999

As the 5th series of the study on the family Lecithoceridae in Sri Lanka, 24 species of Timyra Walker including 5 new species, and 8 species of Doxogenes Meyrick including 3 new species, are recognized. Among them 4 species of Timyra Walker and 2 species of Doxogenes Meyrick, which were previously described from Sri Lanka, were not found during the study. Timyra praeceptrix Meyrick is synonimized with T. mendicella Walker, and T. stachyophora Meyrick wth T. orthadia Meyrick. Descrption of the new species, with illustrations of their genitalia are given.

• Journal of the Ergonomics Society of Korea
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• v.28 no.2
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• pp.17-26
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• 2009

In this study, anthropometric analysis and usability evaluation for four-wheeled walker were carried out and then ergonomics design guidelines were proposed. In anthropometric analysis, design factors of four-wheeled walker were firstly identified and anthropometric design guidelines were made using Korean human scales. Design suitability for two typical four-wheeled walkers was analyzed in based on anthropometric design guidelines. Usability evaluation for two typical walkers was also performed through observation method and expert evaluation. Several usability problems were identified and design solutions were proposed for the design improvement of four-wheeled walker. Finally a design model of four wheeled walker considering analysis results was proposed.

• Archives of Craniofacial Surgery
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• v.13 no.1
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• pp.54-56
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• 2012

Purpose: Dandy-Walker syndrome is a rare congenital brain malformation that occurs one in every 25,000-35,000 live births, mostly in females. It is characterized by cystic enlargement of the fourth ventricle, agenesis or hypogenesis of the cerebellar vermis and enlargement of the posterior fossa. In this report, the authors aimed to address a rare case of a 14-months-old female Dandy-Walker syndrome patient that is presented with submucous cleft palate. Methods: A 14-months-old female patient admitted to our outpatient clinic, via the department of pediatrics, with the complaints of nasal regurgitation, choking and breathing difficulties. She was diagnosed as Dandy-Walker syndrome by magnetic resonance imaging evaluation, at another hospital and underwent a shunt operation for the hydrocephalus continuing treatments. On physical examination, she had structural abnormality of bifid uvula, and palpable notch in the posterior surface of the hard palate. Her submucous cleft palate was corrected, which used a double opposing Z-plasty under general anesthesia. Results: In a follow-up period of 2 months, no complications, such as wound dehiscence, necrosis and infection occurred, which shows satisfactory results. She consulted with pediatric neurologists and physical therapists for further evaluation and management of the abnormalities in the central nervous system. Conclusion: Dandy-Walker syndrome patient with a cleft palate is a very rare case to find, which only a few cases are reported around the world. Authors would like to share this case of Dandy-Walker syndrome patient, with submucous cleft palate, who underwent a double opposing Z-plasty that shows satisfactory results.

• Journal of the Korea Convergence Society
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• v.6 no.2
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• pp.19-24
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• 2015

Nowadays, the number of people who do not move actively or are treated for rehabilitation is increasing because of the disorder or the paralysis of their own lower body by the industrial disaster. In this study, the walker for the people whose bodies are not convenient or the old is investigated. The walkers due to the height of walker are designed and the structural simulation analysis is carried out. The study models of walker are modelled with CATIA program and analyzed with ANSYS program. As the analysis result, the models of 1, 2 and 3 have the maximum stresses extremely below the yield stress of this model and the elastic deformations at these models occurs. Among these models, As the maximum deformation of model 3 has the least value among these models, models 3 is thought to have the best durability. The safety of walker model can be estimated by the basis of the result of this study. The damage can be prevented and the durability is examined by applying this result into the design of walker. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.3
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• pp.339-348
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• 2012

Purpose : The purpose of this study is to compare muscle activations of neck, trunk and leg in cerebral palsy of spastic diplegia with genu recurvatum and knee flexion contracture, when using anterior and posterior walkers. Methods : We selected 21 cerebral palsy and received the written consent to participate in this study. The inclusion criteria for participation required patients to have spastic diplegic CP; to be between 3~6 years of age, to have a GMFCS III grade, to have no botulinum toxin injection and orthopedics surgery within before six months starting the study. Measurements of muscle activities (sternocleidomastoid, splenius capitis, rectus abdominis, erector spinea, gluteus maximus, rectus femoris, medial hamstring and calf muscles) were evaluated anterior and posterior walker ambulations. Statistical evaluation of these data were accomplished by utilizing the paired t-test and independent t-test by SPSS 20.0 program. Significance level was set at p<.05. Results : The following results were obtained. There was significant difference on muscle activation of neck, trunk and legs(soleus except) in anterior and posterior walkers. There was no significant difference in muscle activation of neck but significant difference in muscle activation of trunk, legs between genu recurvatum and knee flexion contracture(rectus abdominis, medial hamstring when using anterior walker, rectus abdominis, erector spinea, gluteus maximus, medial hamstring when using posterior walker). Conclusion : The conclusion of this study is the different knee joint forms would have different effect on muscle activation of trunk and legs while cerebral palsy of spastic diplegic ambulated with anterior walker and posterior walker.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2493-2503
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• 2018

Passive dynamic walking exhibits humanoid and energy efficient gaits. However, optimal design of passive walker at multi-variable level is not well studied yet. This paper presents a Chaotic Particle Swarm Optimization (CPSO) algorithm and applies it to the optimal design of flexible passive walker. Hip torsional stiffness and damping were incorporated into flexible biped walker, to imitate passive elastic mechanisms utilized in human locomotion. Hybrid dynamics were developed to model passive walking, and period-one gait was gained. The parameters global searching scopes were gained after investigating the influences of structural parameters on passive gait. CPSO were utilized to optimize the flexible passive walker. To improve the performance of PSO, multi-scroll Jerk chaotic system was used to generate pseudorandom sequences, and chaotic disturbance would be triggered if the swarm is trapped into local optimum. The effectiveness of CPSO is verified by comparisons with standard PSO and two typical chaotic PSO methods. Numerical simulations show that better fitness value of optimal design could be gained by CPSO presented. The proposed CPSO would be useful to design biped robot prototype.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1423-1424
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• 2010

• Communications of the Korean Mathematical Society
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• v.30 no.2
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• pp.109-121
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• 2015

In this paper, we investigate horizontal lightlike hypersurfaces of Robertson-Walker spacetimes. Some results involving the unique existence of the screen distribution and the symmetry of the induced Ricci curvature tensor of horizontal lightlike hypersurfaces are presented. We also obtain some properties concerning the symmetry and the parallelism of the second fundamental forms of such lightlike hypersurfaces.

• The Korean Journal of Zoology
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• v.7 no.2
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• pp.53-57
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• 1964

In this paper the author has newly recorded fifteen species of moths from Korea as follows : Acrodontis fumosa PROUT (Geometridae) , Dendrolimus yamadai NAGANO(Lasiocampidae), Mirina christophi STAUDINGER(Endromidae), Ramesa tosta WALKER (Notodontidae). Apamea scolopacina subbrunnea WAREEN(Noctuidae), Anuga multiplicans WALKER (Noctuidae), Bena karaeffti GRAESER(Noctuidae), Macrochochthonia fervens BUTLER (Noctuidae) ,Hyposada brunnea LEECH (Noctuidae), Catocala eminens STAUDINGER (Noctuidae), Bleptina contigua LEECH (Noctuidae), Dichromia orosia CRAMER (Noctuidae), Diarsia pacifica BOURSIN (Noctuidae), Nyctemera plagifera WALKER (arctiidae), Phyllosphingia dissimilis BREMER (Sphingidae).