• 한국유체기계학회 논문집
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• 제8권1호
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• pp.7-15
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• 2005

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 running 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.

• 한국운동역학회지
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• 제29권3호
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• pp.145-155
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• 2019

Objective: The purpose of this study was to compare the physical characteristics (bone mineral density, joint muscle strength) and running biomechanics between older adults and young adult runners to understand the changes of running strategy by aging. Method: Bone mineral density (Dual Energy X-ray Absorptiometry, USA) of lower lower extremity and muscle strength (Cybex Humac Norm [DEXA], CSMI, USA) were measured to identify the physical characteristics of 10 elderly (age: $67.70{\pm}3.30yrs$, height: $1.68{\pm}0.04m$, mass: $67.70{\pm}3.80kg$) and 10 young adults (age: $21.20{\pm}0.42yrs$, height: $1.73{\pm}0.06m$, mass: $72.11{\pm}4.15kg$). Running data was collected by using an instrumented treadmill (Bertec, USA) and 7 infrared cameras (Oqus 300, Qualisys, Sweden). Two-way repeated ANOVA analysis was used to analyze results at a significant level of .05 with Bonferroni post hoc analysis. Results: Compared to the young adult group, the elderly group showed statistically significant difference in physical characteristics and in running characteristics. Elderly runners showed lower BMD and muscle strength compared with young runners (p<.05). In the running parameters, elderly runners tend to show shorter contact time and stride length compared with young runners (p<.05). In the joint angles, elderly runners showed smaller range of ankle motion compared with young runners (p<.05). Finally, elderly runners showed lower level of joint moment, joint power, and GRF compared with young runners in each running speed (p<.05). Conclusion: The running behavior of the elderly performed periodic running was similar to many variables of young adults. However, there were noticeable differences found in the ankle joints and most kinetic variables compared with young adult runners. This discrepancy may propose that elderly runners should consider appropriate running distance and intensity in the program.

• 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.

• 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.

• 한국운동역학회지
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• 제19권3호
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• pp.581-592
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• 2009

본 연구는 일반운동화와 스프링신발의 운동역학적 분석을 통해 일상적인 보행에서 스프링신발이 갖는 특성을 알아보기 위해 실시하였다. 이를 위해 정상족궁인 30-40대 여성 12명을 대상으로 2종류의 실험용 신발(스프링신발)과 비교용 신발(일반운동화)을 착용시킨 후 1.7m/s의 보행속도에서 지면반력기와 EMG, 적외선 카메라를 이용한 운동 역학적 분석을 실시하였다. 분석 결과 지면반력 분석에서는 제 1정점과 제 2정점에서 실험용신발이 일반운동화에 비해 큰 전후성분값을 나타냈다. 근전도분석에서는 대퇴직근의 활동이 스프링 신발을 신었을 때 증가하는 것으로 나타났다. 후족각에서 스프링 신발이 착지 시와 제1정점간에 일반화보다 크며 발목 관절을 중심으로 내측으로 회전하는 회내 운동을 적절하게 제어 하면서 이지 시에 후족 각의 감소에 영향을 미치는 것으로 나타났다. 따라서 스프링신발은 일반 신발에 비해 보행 시 무릎 신전근들의 근력 향상에는 도움을 줄 수 있을 것으로 판단된다.

• 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.

• 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.

• 지식경영연구
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• 제11권1호
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• pp.37-50
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• 2010

Bioharmaceutical technologies have consistently been areas in which large licensing agreements have been negotiated. However, there are very limited informations in the open literature on how its running royalty rates are determined and no specific methods are yet provided. The purpose of this study is to suggest an appropriate method for the estimation of running royalty of bioharmaceutical technology in licensing agreements. Here distribution of risk-adjusted operating margins are obtained by simulation using statistics of success rates in the stage of clinical trials and profit margins. Three factors based on technology, business and license legal terms are considered and combined as licensing competitiveness level. Finally, reasonable running royalty is estimated by combining simulated distribution and licensing competitiveness level. This suggested method is expected to practically useful for licensor to establish an appropriate running royalty rate for licensing.

• 한국운동역학회지
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• 제16권1호
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• pp.119-128
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• 2006

This study was performed to see ground reaction force with different soccer studs with twelve players in Human Performance Laboratory(University of Calgary). Running speed was $4.0{\pm}0.2m/sec$ in straight running as well as vcut running. By using four different kinds of shoes; three different pairs of soccer shoes and one pair of jogging shoes, I reached a conclusion as following. In case of right and left ground reaction force, on the assumption that the positive magnitude of power is inversion and the negative is eversion, vcut running did not occur any inversion, which in the aspect of kinetic mechanics, thought to be decelerating movement. Because when eversion happens, it arises component force of power on heading direction about 8.6 times more than in the movement of straight running. In case of front and rear ground reaction, on the assumption that the positive magnitude of power is suspension power and the negative is propulsion, vcut movement is thought to be decelerating movement in the aspect of kinetic mechanics. Because on heading direction, this movement occurs component force of power about 1.8 times more suspension and 2.2 more propulsion than in the straight running movement. In case of vertical ground reaction, on the assumption that the first peak is the magnitude of power in impact and the second peak is the magnitude of power in active, we judged that the straight running movement performed more efficiently than the vcut movement in the aspect of kinetic mechanics. On the next study, I suppose that vcut running would make up an interesting subject in the aspect of improving kinetic performance ability.

• 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.