• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.411-418
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• 2004

Tip clearance of centrifugal compressor affects the performance. Larger tip clearance results in lower efficiency. What really affects the performance is the running tip clearance, not the cold tip clearance. When the compressor is operating, blade strain and the pressure difference between impeller backplate and hub affects the running tip clearance. This paper describes measured running tip clearance and its effects on the performance of centrifugal compressor. Cold tip clearance before operation was 0.4 mm and running tip clearance varied from 0.86 mm to 0.25 mm with impeller exit pressure. As the pressure at impeller exit increases, the routing tip clearance tends to decreases. The target running tip clearance for compressor at $100\%$ speed was 0.3 mm and it turned out to be exactly 0.30 mm from experiment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1782-1793
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• 2008

Republic of korea has begun operating high speed train service according as KTX service operation starts in 2004. Also, EMU whose maximum speed is over 150 kph will be starting to service with electrification and improvement of existing railroad. Moreover, metropolitan electric railways have begun an express service to increase scheduled speed. Therefore, running resistance of rolling stock becomes more important factor effects on the performance. Running resistance of rolling stock is the factor which is necessary for the performance or operation plan of rolling stock, and it's related to rolling friction, slip friction, drag force, gradient, acceleration, curvature, tunnel condition and so on. It is possible to be calculated by CFD (Computational Fluid Dynamics). However it is predicted by experimental equation from running resistance test because of the complex calculation and manifold variables. In this paper, studies about running resistance of rolling stock is introduced, and each term of experimental equation is studied through theoretical approximation. Also, running resistance of rolling stock is estimated by the result of running resistance test, and effects being related to friction, drag force, gradient is examined.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.908-912
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• 2008

Structure-borne noise is known to dominate internal running noise levels in open field. In this paper vibration isolation characteristics of floors are investigated to see their effect on the internal running noise. By using the analysis and test results of test specimen of small size, internal running noise level of complete train is estimated. Analysis results show that soft rubber as a vibration isolator has the most favorable effect on the inside running noise.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2001년도 추계산학기술 심포지엄 및 학술대회 발표논문집
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• pp.85-90
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• 2001

This study is object to structural analysis of household running machine frame. The finite element model was developed to compute the stress, strain and natural frequency for household running machine frame. For structural analysis using result from FEM Code. In other to structural analysis of household running machine frame, many variables such as load condition, boundary condition and weight condition are considered.

• 한국운동역학회지
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• 제26권1호
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• pp.31-37
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• 2016

Purpose: The purpose of this study was to investigate the differences in FT (free-torque) components between non-fatigue and fatigue conditions induced by prolonged running. Methods: Fifteen healthy runners with no previous lower-extremity fractures ($22.0{\pm}2.1$ years of age) participated in this study. Ground reaction force data were collected for the right-stance phase for 10 strides of 5 and 125-min running periods at 1,000 Hz using an instrumented force platform (instrumented dual-belt treadmills, Bertec, USA) while the subjects ran on it. The running speed was set according to the preferences of the subjects, which were determined before the experiment. FT variables were calculated from the components of the moment and force output from the force platform. A repeated-measures one-way ANOVA was used to test for significant differences between the two conditions. The alpha level for all the statistical tests was 0.05. Results: The absolute FT at the peak braking force was significantly greater after 5 mins of running than after 125 mins of running-which was regarded as a fatigued state-but there were no significant differences in the absolute peak FT or impulse between the conditions. Conclusion: The FT variables in the fatigue condition during prolonged running hardly affect the tibial stress syndrome.

• 한국운동역학회지
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• 제31권1호
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• pp.59-63
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• 2021

Objective: Through comparative analysis of muscle activity for whole-body vibration, walking and running movements, it is to verify the training effect of whole-body vibration exercise in terms of amount of exercise and muscle activity characteristics. Method: Flat ground walking and slope walking (10 degrees) at a speed of 5 km/h, flat ground running and slope running (10 degrees) at a speed of 11 km/h for running were performed on treadmill, and squats were maintained at 12 Hz, 20 Hz, and 29 Hz conditions on Whole body vibration exercise equipment (Galileo). Muscle activity was analyzed through EMG analysis device for one minute for each condition. Results: The Anterior Tibialis and Erector Spinae show greater exercise effect in whole-body vibration than walking and running. The Rectus Femoris, Biceps Femoris, and Gluteus Maximus have the best effect of exercise in flat running. Whole-body vibration exercise showed greater muscle activation effect as the frequency increased, and exercise effect similar to walking during the same exercise time. Conclusion: The amount of exercise through Whole-body vibration exercise was similar to that of walking exercise, and the Anterior Tibialis and Erector Spinae shows better exercise effect than walking and running.

• 운동영양학회지
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• 제24권1호
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• pp.1-8
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• 2020

[Purpose] This study compared differences in trabecular bone architecture and strength caused by jump and running exercises in rats. [Methods] Ten-week-old male Wistar rats (n=45) were randomly assigned to three body weight-matched groups: a sedentary control group (CON, n=15); a treadmill running group (RUN, n=15); and a jump exercise group (JUM, n=15). Treadmill running was performed at 25 m/min without inclination, 1 h/day, 5 days/week for 8 weeks. The jump exercise protocol comprised 10 jumps/day, 5 days/week for 8 weeks, with a jump height of 40 cm. We used microcomputed tomography to assess microarchitecture, mineralization density, and fracture load as predicted by finite element analysis (FEA) at the distal femoral metaphysis. [Results] Both jump and running exercises produced significantly higher trabecular bone mass, thickness, number, and fracture load compared to the sedentary control group. The jump and running exercises, however, showed different results in terms of the structural characteristics of trabecular bone. Jump exercises enhanced trabecular bone mass by thickening the trabeculae, while running exercises did so by increasing the trabecular number. FEA-estimated fracture load did not differ significantly between the exercise groups. [Conclusion] This study elucidated the differential effects of jump and running exercise on trabecular bone architecture in rats. The different structural changes in the trabecular bone, however, had no significant impact on trabecular bone strength.

• 한국ITS학회 논문지
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• 제15권1호
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• pp.77-86
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• 2016

운전자는 다양한 종류의 교통정보를 여러 방식을 통해 받을 수 있지만, 인적요소를 고려한 정보 서비스는 이루어지지 않고 있다. 본 연구는 운전자 인적요소에 대한 기초 연구를 실행하기 위해 고속국도 주행 시 다양한 주행환경에서 속도의 차이에 따른 운전자 평균 주시시간의 특성 분석을 목표로 하였다. 분석 시 속도 외에 영향을 줄 수 있는 변수를 통제하기 위하여 주행상황을 '주간에 선행 차량 없이 주행', '주간에 선행 차량이 존재하는 상황에서 주행', '야간에 선행 차량 없이 주행', '야간에 선행 차량이 존재하는 상황에서 주행' 4가지로 분류하였다. ANOVA Test를 활용하여 속도 그룹을 나누었으며 그룹별 평균 주시시간의 차이를 비교하기 위해 다중비교(multiple comparison)를 한 결과 도로, 선행 차량 항목은 속도가 증가함에 따라 평균 주시시간이 증가하고 전경 항목은 평균 주시시간이 감소하는 것으로 나타났다. 도로표지 항목은 속도에 따라 주시시간의 차이가 통계적으로 무의미한 것을 확인할 수 있었다.

• 한국안전학회지
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• 제32권5호
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• pp.41-46
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• 2017

The coefficient of derailment and the rate of wheel load reduction were used as the index of train running safety that was directly affected the train derailment safety. In aspects of track, the train running safety depends on the complex interaction between wheel and rail, and the track-vehicle conditions (i.e., the curvature, cant, track system, vehicle speed and the operation conditions, etc). In this study, the relationship between the train running safety and the track curvature and vehicle speed for direct fixation concrete tracks currently employed in Korean light rapid transit was assessed by performing field tests using actual vehicles running along the service lines. The measured dynamic wheel load, lateral wheel load and lateral displacement of rail head were measured for same train running on four tested tracks under real conditions, which included curved and tangent tracks placed on the tunnel and bridge, thus increasing the train speed by approximately maximum design speed of each test site. Therefore, the measured dynamic track response was applied to the running safety analysis in order to evaluate the coefficient of derailment, the rate of wheel load reduction and the track gauge widening at each test site, and compare with the corresponding Korean train running safety standard. As the results, the lateral track response of direct fixation concrete track appeared to increase with the decreased track curvature; therefore, it was inferred that the track curvature directly affected the train running safety.

• 한국운동역학회지
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• 제15권3호
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• pp.1-7
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• 2005

Excessive pronation and impact force during running are related to various running injuries. To prevent these injuries, three type of running shoes are used, such as cushioning, stability, and motion control. Although there were may studies about the effect of midsole hardness on impact force, no study to investigate biomechanical effect of motion control running shoes. The purpose of this study was to determine biomechanical difference between cushioning and motion control shoes during treadmill running. Specifically, plantar and rearfoot motion, impact force and loading rate, and insole pressure distribution were quantified and compared. Twenty male healthy runners experienced at treadmill running participated in this study. When they ran on treadmill at 3.83 m/s. Kinematic data were collected using a Motion Analysis eight video camera system at 240 Hz. Impact force and pressure distribution data under the heel of right foot were collected with a Pedar pressure insole system with 26 sensors at 360 Hz. Mean value of ten consecutive steps was calculated for kinematics and kinetics. A dependent paired t-test was used to compare the running shoes effect (p=0.05). For most kinematics, motion control running shoes reduced the range of rearfoot motion compared to cushioning shoes. Runners wearing motion control shoe showed less eversion angle during standing less inversion angle at heel strike, and slower eversion velocity. For kinetics, cushioning shoes has the effect to reduce impact on foot obviously. Runners wearing cushioning shoes showed less impact force and loading rate, and less peak insole pressure. For both shoes, there was greater load on the medial part of heel compared to lateral part. For pressure distribution, runners with cushioning shoes showed lower, especially on the medial heel.