• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.67-74
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• 2016

Purpose: Many tractors have adopted the horizontal control system designed to maintain the three-point mounted implements in horizontal position when they are tilted sideways. The control system rotates the implement in the opposite direction to the inclination of rear axle of the tractor. However, the current control system was found to have poor performance in accuracy and response. A new control system was therefore developed to improve the performance. Methods: The new control system was designed to get the response of the implement to be started earlier by using the tilt information from the front axle of the tractor. By this approach, the rotation of the implement can be adjusted as required to make it horizontal at the expected time, even though the response is slow. The optimal values of the control parameters for the new system were determined by computer simulation and validated by a performance test conducted with an obstacle of 120 mm height on a flat concrete surface. The performance of the control system was evaluated by the root mean square error (RMSE) of the rotation angle of the implement with respect to the actual inclination of the rear axle. Results: The new control system reduced the RMSE of the current control system by 44.6% indicating a high performance improvement. The inclination of the front axle was easily obtained from a sensor mounted on the front axle of the tractor and used as input to the new control system. Conclusions: The method of getting the response of the implement to be started earlier by utilizing the inclination information of the front axle can be applied to improve the performance of the current control system at least cost.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.213-217
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• 2006

An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle) which has been developed by KARI (Korea Aerospace Research Institute). For teaming the NN, a BPN with one hidden, one input and one output layer was used. The input layer had seven neurons of variations of measurement parameters such as SHP, MF, P2, T2, P4, T4 and T5, and the output layer used 6 neurons of degradation ratios of flow capacities and efficiencies for compressor, compressor turbine and power turbine. Database for network teaming and test was constructed using a gas turbine performance simulation program. From application results for diagnostics of the PW206C turboshaft engine using the learned networks, it was confirmed that the proposed diagnostics algorithm could detect well the single fault types such as compressor fouling and compressor turbine erosion.

• Clinical and Experimental Pediatrics
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• v.59 no.11
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• pp.451-455
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• 2016

Purpose: Neurocardiogenic syncope (NCS) is the most frequent cause of fainting during adolescence. Inappropriate cardiovascular autonomic control may be responsible for this clinical event. The head-up tilt test has been considered a diagnostic standard, but it is cumbersome and has a high false-positive rate. We performed a study to evaluate whether P-wave dispersion (PWD) could be a useful electrocardiographic parameter of cardiac autonomic dysfunction in children with NCS. Methods: Fifty-four patients with NCS (28 boys and 26 girls; mean age, $12.3{\pm}1.4$ years) and 55 age- and sex-matched healthy controls were enrolled. PWD was obtained as the difference between maximum and minimum durations of the P wave on standard 12-lead electrocardiography in all patients and controls Results: The value of PWD was significantly higher in the syncope group than in the control group ($69.7{\pm}19.6$ msec vs. $45.5{\pm}17.1$ msec, respectively; P<0.001). The minimum duration of P wave was shorter in the syncope group than in the control group ($43.8{\pm}16.8$ msec vs. $53.5{\pm}10.7$ msec, respectively; P<0.001). Left atrial volume was not different between the groups on transthoracic echocardiography. Conclusion: PWD on echocardiography could be used as a clinical parameter in patients with NCS.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.165-172
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• 2006

The purpose of this study was to determine effects of 12-week wearing of unstable shoe on the standing posture and gait mechanics. Nine healthy men were asked to wear the unstable shoes for 12-week and walk for 30 minute everyday. Their standing posture and gait mechanics were measured before and after treatment. Standing posture was measured for each side(anterior, posterior, lateral) for standing position. And gait analysis was measured joint angle of a right lower limb between first right heel contact and second right heel contact. Kinematic data were collected using video camera at 30 frame per seconds. Statistical analysis was paired t-test(p<.05) to compare before training with after that. A head tilt angle was significantly decreased for posterior side(p<.05). The angle of between center of line and surface was significantly decreased at midstance and take off during walking(p<.05). Ankle dorsiflexion significantly increased at heel contact2(p<.05) and ankle plantarflexion significantly increased at midstance and midswing(p<.05). The increase of ankle dorsiflexion showed that our results consisted with previous study. In conclusion, there was not large significant difference in static standing posture but joint angle of lower limb represented many changes with increasing of ankle motion during walking. These were of benefit to body by increasing leg muscle activity but it was necessary for man having a ankle problem to consider. Further studies concerning optimum outsole angle of unstable shoes are necessary.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.281-284
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• 2006

An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle) which has been developed by KARI (Korea Aerospace Research Institute). The measurement parameters of Smart UAV propulsion system are gas generator rotational speed, power turbine rotational speed, exhaust gas temperature and torque. But two measurement such as compressor exit pressure and compressor turbine exit temperature were added because they were difficult each component diagnostics using the default measurement parameter. The performance parameters for the estimate of component performance degradation degree are flow capacities and efficiencies for compressor, compressor turbine and power turbine. Database for network learning and test was constructed using a gas turbine performance simulation program. From application results for diagnostics of the PW206C turboshaft engine using the learned networks, it was confirmed that the proposed diagnostics could detect well the single fault types such as compressor fouling and compressor turbine erosion.

• Physical Therapy Korea
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• v.22 no.1
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• pp.93-102
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• 2015

Prolonged sitting can contribute to low back pain. The lumbar taping can be applied to correct the sitting posture. This study aimed to investigate the effect of lumbar taping on lumbar kinematics and the muscle activities of multifidus (MF) and internal oblique in the individuals with nonspecific chronic low back pain (NSCLBP) as they type for 30 minutes. Nineteen subjects with NSCLBP (9 people in non taping group and 10 people in taping group) were recruited. Lumbar taping was applied to the taping group before typing. Both groups started typing in a neutral sitting position with their feet on the floor. The change of posture and S2 posterior tilting (S2P) were measured to investigate kinematic data. Three sensors were attached on T12, L3, and S2 to identify the change of posture. Surface electromyography was used to measure the muscle activities. Palpation meter was used to standardize the angle of pelvic tilt in sagittal plane before typing. All instruments were used to measure each data before and after typing. Independent t-test was used to compare the changing values of lumbar kinematics and muscle activities before and after typing between both groups. The changing values of S2P and change of posture of L3 and S2 were significantly smaller in the taping group compared to the non taping group (p<.05). The changing value of muscle activities of MF between before and after typing was significantly smaller in the taping group compared to the non taping group (p<.05). In conclusion, the lumbar taping during the 30-minute typing task can be applied to maintain correct sitting posture in the lumbar and pelvis and to maintain activation of MF.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.145-153
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• 1984

In the present work, a computer simulation is performed employing Hottel-Whillier-Bliss model for thermal performance of solar collectors. The major collector parameters examined in the computer simulation are: number of transparent glass covers(N), thermal emissivity of the absorbing plate surface (.epsilon.$_{P}$), absorptivity of absorber plate (.alpha.$_{p}$), flow rate per unit area of collector (G), $L_{b}$ / $k_{b}$ of insulation material, tilt angle of collector (S), and solar insolation(I). By varying numerical values of the major collector parameters around their typical values, the corresponding variations in thermal efficiency curves are examined. In addition, an experimental investigation has been carried out with a slightly modified KAIST collector test loop under a real sun condition in order to compare with the simulation results, examine the applicability of the mathematical model of the collector thermal performance, and study the effect of variation of flow rate (G) on thermal efficiency and the range of optimum flow rate.e.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.15-22
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• 2006

An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV(Unmanned Aerial Vehicle) which is being developed by KARI (Korea Aerospace Research Institute). For teeming the NN(Neural Network), a BPN(Back Propagation Network) with one hidden, one input and one output layer was used. The input layer has seven neurons: variations of measurement parameters such as SHP, MF, P2, T2, P4, T4 and T5, and the output layer uses 6 neurons: degradation ratios of flow capacities and efficiencies for compressor, compressor turbine and power turbine, respectively, Database for network teaming and test was constructed using a gas turbine performance simulation program. From application of the learned networks to diagnostics of the PW206C turboshaft engine, it was confirmed that the proposed diagnostics algorithm could detect well the single fault types such as compressor fouling and compressor turbine erosion.

• Physical Therapy Korea
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• v.22 no.4
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• pp.17-26
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• 2015

The purpose of this study was to investigate the effects of visual electromyography (EMG) biofeedback on the EMG activity of the lower trapezius (LT), serratus anterior (SA), and upper trapezius (UT) muscles, the LT/UT and SA/UT EMG activity ratios, and the scapular upward rotation angle during scapular posterior tilting exercise (SPTE). Twenty-four subjects with round-shoulder posture participated in this study. The EMG activities of the LT, SA, and UT were collected during SPTE both without and with visual EMG biofeedback. The scapular upward rotation angle was measured at the baseline, after SPTE without visual EMG biofeedback, and after SPTE with visual EMG biofeedback. The LT, SA, and UT EMG activities, and the LT/UT and SA/UT EMG activity ratios were analyzed by paired t-test. The scapular upward rotation angle was statistically analyzed using one-way repeated analysis of variance. If a significant difference was found, a Bonferroni correction was performed (p=.05/3=.017). The EMG activities of LT and SA significantly increased, and the EMG activity of UT significantly decreased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). In addition, the LT/UT and SA/UT EMG activity ratios significantly increased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). Significant increases were found in the scapular upward rotation angle after SPTE without and with visual EMG biofeedback compared to baseline (p<.017), and no significant differences were observed in the scapular upward rotation angle between SPTE without and with visual EMG biofeedback. In conclusion, SPTE using visual EMG biofeedback may be an effective method for increasing LT and SA activities while reducing UT activity.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.169-178
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• 1999

Low-field anisotropy of magnetic susceptibility (AMS) was measured with 247 samples from 17 sites of Pre-Cambrian anorthositic rocks in the Hadong-Sanchong area, southwestern part of the Ryongnam Block. Tectonic stress-direction is defined by the minimum susceptibility (k3) direction, and flow-direction by the maximum susceptibility (k1) direction. Five sites rendered self-consistent NW-SE site-mean tectonic stress-direction. Even though a general fold test for every site was not possible due to the homoclinal nature of the bedding attitudes, a site with various bedding attitudes shows far better clustering of the k3-direction before the bedding-tilt correction. The in-situ NW-SE tectonic stress-direction is consistent over the study area and compatible with petrographic foliation observed in metamorphic rocks in and arround the study area, suggesting a regional compressive force acted after the emplacement of the anorthositic rocks. On the other hand, flow-directions obtained from six sites varies from site to site. Strong-field IRM experiments show predominance of titanomagnetites over a small amount of hematite in some samples.