• 한국운동역학회지
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• 제28권3호
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• pp.159-164
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• 2018

Objective: The aims of this study were to determine the impact peak force and kinematic variables in running speed and investigate the relationship between them. Method: Thirty-nine male heel strike runners ($mean\;age=21.7{\pm}1.6y$, $mean\;mass=72.5{\pm}8.7kg$, $mean\;height=176.6{\pm}6.1cm$) were recruited in this investigation. The impact peak forces during treadmill running were assessed, and the kinematic variables were computed using three-dimensional data collected using eight infrared cameras (Oqus 300, Qualisys, Sweden). One-way analysis of variance ANOVAwas used to investigate the influence of the running speed on the parameters, and Pearson's partial correlation was used to investigate the relationship between the impact peak force and kinematic variables. Results: The running speed affected the impact peak force, stride length, stride frequency, and kinematic variables during the stride phase and the foot angle at heel contact; however, it did not affect the ankle and knee joint angles in the sagittal plane at heel contact. No significant correlation was noted between the impact peak force and kinematic variables in constantrunning speed. Conclusion: Increasing ankle and knee joint angles at heel contact may not be related to the mechanism behind reducing the impact peak force during treadmill running at constant speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.266-268
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• 2004

In this study, on-line measuring system were developed to verify performances and functions of traction system that are used in KTX(Korea Train eXpress) synthetically and efficiently, and have been measuring electric signals of vehicle as well as mechanical signals up to the present. Running-braking measuring equipment was constructed in vehicle to optimize signal acquisition and analysis ability of the measuring system. Measurement data of signal were performed acquisition, analysis and evaluation using this equipment. KRRI(Korea Railroad Research Institute) described about main specifications of measuring equipment. Also, the structure and principles as well as main circuit system were explained in brief. KRRI analyzed the characteristics comparing design values with experimental values about running distance, running time and positive acceleration for KTX is running in full traction. We analyzed the distance and time according to number of motor block. In result, running characteristics of traction system in KTX were verified and could be evaluated.

• 대한정형도수물리치료학회지
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• 제22권2호
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• pp.65-69
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• 2016

Background: The purpose of this study was to determine whether place running exercise that combines thoracic mobility exercise program increases pulmonary function of the 20s subjects. Method: Thirty subjects in their 20s were randomly assigned to on experimental group (n=15) or control group (n=15). Over the course of four weeks, the experimental group participated in place running exercise that combines thoracic mobility exercise program for 30 minutes three times per week and the control group participated in place running exercise and thoracoabdominal stretching exercise for 30 minutes three times per week. Subjects were assessed pre-test and post-test by measurement of pulmonary function Results: Our findings show that the experimental group had significant difference in expiratory reserve volume and vital capacity and maximal voluntary capacity (p<.05). In the comparison of the two groups, the experimental group had higher vital capacity and maximal voluntary capacity than the control group. Conclusion: In this study, the experimental group showed greater improvement in pulmonary function than the control group, which indicates that the place running exercise that combines thoracic mobility exercise program exercise is effective at increasing the pulmonary function.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.279-287
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• 2018

This study investigated applicability of the fast running model for damage assessment of underground structures by ground shock. For this reason, the fast running model that consists of two main models such as the ground shock generation and propagation model and the underground structural damage assessment model was developed. The ground shock generation and propagation model was programed using theoretical formula and empirical formula introduced in TM5-855-1(US army manual). The single degree of freedom model of structural components was utilized to predict structural dynamic displacements which are used as index to assess damage level of components. In order to confirm the feasibility of the developed fast running model, underground structural dynamic displacements estimated from the fast running model were compared to displacements obtained from the finite element analysis.

• 한국운동역학회지
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• 제26권3호
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• pp.257-264
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• 2016

Objective: The purpose of this study was to determine the periodicity of shank-foot segment coupling and free torque before and after fatigue induced by prolonged running. Method: Fifteen young healthy male participants with a rear-foot strike ran on instrumented dual-belt treadmills at 70% of their maximum oxygen uptake for 65 min. Kinematic and ground reaction force data were collected for 20 continuous strides at 5 and 65 min (considered the fatigued condition). The approximate entropy tool was applied to assess the periodicity of the shank internal-external rotation, foot inversion-eversion, shank-foot segment coupling, and free torque for the two running conditions. Results: The periodicity of all studied parameters, except foot inversion-eversion, decreased after 65 min of running (fatigued condition) for 80% of the participants in this study. Furthermore, 60% of the participants showed similarities in the change of periodicity pattern in shank internal-external rotation, coupling, and free torque. Conclusion: The findings indicated that the foot inversion-eversion motion may pose a higher risk of injury than the shank internal-external rotation, coupling, and free torque in the fatigued condition during prolonged running.

• 한국정밀공학회지
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• 제28권5호
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• pp.559-564
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• 2011

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 90km/h for estimating the curving performance and running safety of depressed center flat car of 3-axle bogie. As the test results, could confirm the curving performance and running safety of depressed center fiat car of 3-axle bogie from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.6, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• 한국운동역학회지
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• 제23권3호
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• pp.225-233
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• 2013

The purpose of this study was to estimate the potential injury via analyzing ground reaction force components that were resulted from a prolonged-run-induced fatigue. For the present study, passive and active components of the vertical ground reaction force were determined from time and frequency domain. Shear components of GRF also were calculated from time and frequency domain. Twenty subjects with rear foot contact aged 20 to 30, no experience in injuries of the extremities, were requested to run on the instrumented tread-mill for 160 minutes at their preference running speed. GRF signals for 10 strides were collected at 5, 35, 65, 95, 125, and 155 minute during running. In conclusions, there were no significant difference in the magnitude of passive force, impact load rate, frequency of the passive and active components in vertical GRF between running times except the magnitude of active force (p<.05). The magnitude of active force was significantly decreased after 125 minute run. The magnitude of maximum peak and maximum frequency of the mediolateral GRF at heel strike and toe-off have not been changed with increasing running time. The time up to the maximum peak of the anteroposterior at heel-strike moment tend to decrease (p<.05), but the maximum peak and frequency of that at heel and toe-off moment didn't depend significantly on running time.

• Physical Therapy Rehabilitation Science
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• 제11권1호
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• pp.58-65
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• 2022

Objective: The purpose of this study was to investigate the effect of visual feedback bicycle training on running performance, maximal oxygen uptake and quadriceps muscle strength. Design: A randomized controlled trial. Methods: Fifteen healthy adult men with no musculoskeletal or nervous system disease and capable of bicycle training were included. After the pretest, subjects were randomly assigned to visual feedback bicycle training group and general fixed bicycle training group. Both groups were trained two times a week for three weeks, each week for a fixed time and number of repetitions, followed by a six week washout period and then crossing the training method. visual feedback bicycle training provides visual feedback of heart rate in real time using a monitor and a heart rate meter during bicycle training, and general fixed bicycle training performed general bicycle training without visual feedback. After training, each item was measured using a wearable technology, gas analyzer, isokinetic equipment. Results: The results of this study was significant differences in running performance, maximal oxygen uptake and quadriceps muscle strength in visual feedback bicycle training group (p<0.05). The differential effect was found between visual feedback bicycle training group and general fixed bicycle training group in running performance, maximal oxygen uptake, and quadriceps muscle strength (p<0.05). Conclusions: This study suggested that that visual feedback bicycle training can be applied as a useful training method to improve running performance, maximal oxygen uptake and quadriceps muscle strength.

• Smart Structures and Systems
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• 제30권3호
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• pp.303-315
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• 2022

The degradation of wheel tread may result in serious hazards in the railway operation system. Therefore, timely wheel defect diagnosis of in-service trains to avoid tragic events is of particular importance. The focus of this study is to develop a novel wheel defect detection approach based on the relevance vector machine (RVM) which enables online detection of potentially defective wheels with trackside monitoring data acquired under different running-speed conditions. With the dynamic strain responses collected by a trackside monitoring system, the cumulative Fourier amplitudes (CFA) characterizing the effect of individual wheels are extracted to formulate multiple probabilistic regression models (MPRMs) in terms of multi-kernel RVM, which accommodate both variables of vibration frequency and running speed. Compared with the general single-kernel RVM-based model, the proposed multi-kernel MPRM approach bears better local and global representation ability and generalization performance, which are prerequisite for reliable wheel defect detection by means of data acquired under different running-speed conditions. After formulating the MPRMs, we adopt a Bayesian null hypothesis indicator for wheel defect identification and quantification, and the proposed method is demonstrated by utilizing real-world monitoring data acquired by an FBG-based trackside monitoring system deployed on a high-speed trial railway. The results testify the validity of the proposed method for wheel defect detection under different running-speed conditions.

• 한국산림과학회지
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• 제85권3호
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• pp.513-523
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• 1996

본 연구는 임도의 노선 선형이 차량의 주행속도에 마치는 영향을 규명하고, 임도의 구조를 개선할 수 있는 개선책을 제시하고자 하였다. 이러한 목적을 달성하기 위하여 본 연구는 기존의 임도 설계서 및 설계도면을 검토사여 연구 목적에 부합하는 임도를 선정하고, 연구대상 임도에 대해 종단물매, 노폭, 곡선반지름, 곡선길이, 곡선부의 편구배 등 노선선형 인자와 노면의 상태 등을 측정하였다. 선택된 실험차량을 이용하여 주행실험을 한 결과, 차량의 주행속도에 크게 영향을 미치는 인자는 노면의 상태, 곡선반지름, 학성물매, 곡선길이, 종단물매인 것으로 나타났다. 또한, 실험차량의 주행속도는 임도시설규정에서 제시된 설계속도에 비해 낮은 값을 나타내었으며, 적재시(적차)의 주행 속도는 비적재시(공차)에 비해 70-85%의 값을 보였다. 그리고 노면의 상태에 따라 곡선반지름과 종단물매의 증가에 따른 주행속도의 변화를 식으로 나타낼 수 있었다. 이러한 연구의 결과는 가존의 임도 뿐만 아니라 향후 개설될 임도의 질을 판단하고, 임도에서의 주행속도를 개선시킬 수 있는 임도 구조의 선택을 가능하게 할 것으로 생각된다.