Stability analysis and control for bipedal locomotion using energy methods

In this thesis, we investigate the stability of limit cycles of passive dynamic walking. The formation process of the limit cycles is approached from the view of energy interaction. We introduce for the first time the notion of the energy portrait analysis originated from the phase portrait. The energy plane is spanned by the total energy of the system and its derivative, and different energy trajectories represent the energy portrait in the plane. One of the advantages of this method is that the stability of the limit cycles can be easily shown in a 2D plane regardless of the dimension of the system. The energy portrait of passive dynamic walking reveals that the limit cycles are formed by the interaction between energy loss and energy gain during each cycle, and they are equal at equilibria in the energy plane. In addition, the energy portrait is exploited to examine the existence of semi-passive limit cycles generated using the energy supply only at the take-off phase. It is shown that the energy interaction at the ground contact compensates for the energy supply, which makes the total energy invariant yielding limit cycles. This result means that new limit cycles can be generated according to the energy supply without changing the ground slope, and level ground walking, whose energy gain at the contact phase is always zero, can be achieved without actuation during the swing phase. We design multiple switching controllers by virtue of this property to increase the basin of attraction. Multiple limit cycles are linearized using the Poincare map method, and the feedback gains are computed taking into account the robustness and actuator saturation. Once a trajectory diverges from a basin of attraction, we switch the current controller to one that includes the trajectory in its basin of attraction. Numerical simulations confirm that a set of limit cycles can be used to increase the basin of attraction further by switching the controllers one after another. To enhance our knowledge of the limit cycles, we performed sophisticated simulations and found all stable and unstable limit cycles from the various ground slopes not only for the symmetric legs but also for the unequal legs that cause gait asymmetries. As a result, we present a novel classification of the passive limit cycles showing six distinct groups that are consecutive and cyclical

Effects of fire fight safety education when applied metaverse in Korea: Focusing on the construction industry

This study reviewed educational, aesthetic, entertainment and deviant experiences which are elements of the metaverse experience set them as research variables   and presented the results of the study through a survey. First, it was found that the educational experience was statistically significant for safety education satisfaction and had a positive effect. In order to provide practical education, educational experiences must feel like reality and fun content must be easily delivered. Second, it was found that deviant experiences were statistically significant for   safety education satisfaction and had a positive effect. This can be said to increase the prevention of safety accidents only when the deviant experience service feels like reality and interesting contents related to safety education are easily delivered. Third, it was found that the aesthetic experience was statistically significant for safety education satisfaction and had a positive effect. This can be said to increase the prevention of safety accidents only when aesthetic experiences and services feel like reality and interesting contents related to safety education are easily delivered. Fourth, it was found that the recreational experience was statistically significant for safety education satisfaction and had a positive effect. This can be said to increase the prevention of safety accidents only when entertainment and deviant experience services feel like reality and interesting contents related to safety education are easily delivered

Electrogenic transport and K(+) ion channel expression by the human endolymphatic sac epithelium.

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid

Outcomes of Palivizumab Prophylaxis for Respiratory Syncytial Virus Infection in Preterm Children with Bronchopulmonary Dysplasia at a Single Hospital in Korea from 2005 to 2009

This study was performed to evaluate the utilization and outcomes of palivizumab in high risk children born prematurely with chronic lung disease (CLD). A retrospective review of 128 patients was conducted from September 2004 to March 2009 at the Ajou University Hospital. All patients were diagnosed with CLD, were born at ≤35 weeks of gestation, were <2 yr old at the onset of respiratory syncytial virus (RSV) season, and had received medical therapy within six months prior to the RSV season. Fifty-three patients did not receive palivizumab prophylaxis and 75 patients received at least one dose of palivizumab. There were no statistically significant differences between the patients with and without palivizumab prophylaxis with regard to demographic characteristics and risk factors for RSV infection. There were no systemic adverse responses. Compliance with the course of prophylaxis was 92.2%. Hospitalization associated with RSV occurred in 12 cases (22.6%) in the group without prophylaxis and in three cases (4.0%) with prophylaxis. Palivizumab prophylaxis significantly reduced the frequency of RSV-related hospitalization in preterm children with CLD. This is the first retrospective review of palivizumab prophylaxis in Korea. Palivizumab is effective and well tolerated in high risk prematurely born children

Multidirectional Instability Accompanying an Inferior Labral Cyst

Paralabral cyst of the shoulder joint can be observed in 2% to 4% of the general population, particularly in men during the third and fourth decade. On average, these cysts measure 10 mm to 20 mm in diameter and are located preferentially on the postero-superior aspect of the glenoid. The MRI has increased the frequency of the diagnosis of paralabral cysts of the shoulder joint. Paralabral cysts of the shoulder joint usually develop in the proximity of the labrum. The relationship between shoulder instability and labral tears is well known, however, the association of shoulder instability with a paralabral cyst is rare. Shoulder instability may cause labral injury or labral injury may cause shoulder instability, and then injured tear develops paralabral cyst. In our patient, the inferior paralabral cyst may be associated with inferior labral tears and instability MRI

COMPARISON OF PROPRIOCEPTION PERCEPTION TEST BETWEEN GOLFER AND NON-GOLFER USING TILTING PLATFORM

The purpose of this study was to test proprioception perception and compare between collegiate golfers and non-golfers using tilting platform. Sixteen male and fourteen female golfers and fifteen male and thirteen non-golfers were participated. All participants were performed perception test on the tilting platform. Frequency analysis and independent t-test were performed using SPSS 24.0. Alpha set at .05. Most participants were perceived from 1° to 2° of slopes and perceived left-right (target direction) slope than forward-backward slope. Repeated practice such as walking on the uneven ground or standing on sloped ground might help to improve proprioception perception. Further research using a tilting platform will be to develop the training program