• 한국전산유체공학회지
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• 제17권1호
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• pp.23-28
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• 2012

The pressure transient inside the passenger cabin of high-speed train has been simulated using computational fluid dynamics(CFD) based on the axi-symmetric Navier-Stokes equation. The pressure change inside a train have been calculated using first order difference approximation based on a linear equation between the pressure change ratio inside a train and the pressure difference of inside and outside of the train. The numerical results have been assessed for the KTX train passing through a 9km long tunnel of Wonju-Kangneung line at the speed of 250km/h assuming that the train is satisfying the train specification for airtightness required by the regulation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.337-342
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• 2011

The pressure transient inside the passenger cabin of high-speed train has been simulated using computational fluid dynamics(CFD) based on the axi-symmetric Navier-Stokes equation. The pressure change inside a train have been calculated using first order difference approximation based on a linear equation between the pressure change ratio inside a train and the pressure difference of inside and outside of the train. The numerical results have been assessed for the KTX train passing through a 9km long tunnel of Wonju-Kangneung line at the speed of 250km/h assuming that the train is satisfying the train specification for airtightness required by the regulation.

• The Journal of Korean Physical Therapy
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• 제25권5호
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• pp.252-259
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• 2013

Purpose: The aim of this study was to evaluate the effect of progressive body weight decrease combined with increasing level of overground walking speed training for patients with chronic stroke. Methods: Eighteen subjects with chronic stroke were composed of the control group (5% body weight support combined with increasing speed training) and the experimental group (progressive body weight decrease with increasing speed training); three sets, three times per week over a period of four weeks. Results: Significant differences in terms of comfortable gait speed (CGS) and the rate of change of CGS were observed between the control and experimental groups (p<0.05). However, no significant difference in the dynamic gait index was observed between the control and experimental groups (p>0.05). A significant difference in the 6 minute walking test (6MWT) was observed for the experimental group, and a significant difference in the rate of change for the 6MWT was observed between the control and experimental groups (p<0.05). Conclusion: The progressive body weight decrease combined with increasing in level of overground walking speed training may be a better and more effective method for community walking and reintegration.

• 한국조경학회지
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• 제28권5호
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• pp.15-25
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• 2000

The purpose of this paper is to examine the visual evaluation structure about the formal changes of streetscape by the different moving speed in two alternative control plans for the building height and the setback regulation. The virtual reality system is applied to the experimental tool. Eighty-two experimental models are made in consideration of the height and the setback of the building regulation cased by Midou-suji street in Osaka City, Japan. and ten typical models are selected by pre-experiment. Since the changes of the landscape structure consists of the height and the setback of the building, four the evaluation items are set: grade of continuity, order, openness, preference. As there are eighty-two landscape models which are too many to be applied in this experiment, ten role models are drawn out and used in this experiment. The mean difference test, discriminant analysis, and multiple linear regression methods had been used for the statistical analysis methods. The results of this study are as follows; 1) It is found out the fact of the difference evaluation structure amount experiments models. 2) From the sketch analysis and interview, it is found out difference cognition structure by the moving speed and alternatives. 3) From the discriminant and regression analysis, it is found out that the evaluation value about continuity becomes low by the moving speed change from walking speed to driving speed. We suggest that continuous experiment should be made with a variety of groups and models, and general and universal results should also be come out of the experiments above.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.521-524
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• 2009

This study describes aerodynamic noise of high speed wind turbine system, which is invented as a new concept in order to reduce the torque of main shaft, for design parameters of the rotor blade. For parametric study of high speed rotor aerodynamic noise, Unsteady Vortex Lattice Method with Nonlinear Vortex Correction Method is used for analysis of wind turbine blade aerodynamic and Farassat1A and Semi-Empirical are used for low frequency noise and airfoil self noise. Parameters are chord length, twist and rotational speed for this parametric research. In the low frequency range, the change of noise is predicted the same level as each parameters varies. However, in case of broadband noise of blade, the change of rotational speed makes more variation of noise than other parameters. When the geometric angles of attack are fixed, as the rotational speed is increased by 5RPM, the noise level is increased by 4dB.

• 대기
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• 제31권1호
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• pp.101-112
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• 2021

The long-term trend of surface wind speed in Korea is examined for 31 KMA weather stations from 1985 to 2019. Most stations, except Daegwallyeong, have several times of anemometer height changes from tens of centimeters to several meters. To minimize such height change effect on long-term wind trend, the present study adjusts anemometer height in each station to the standard height of 10 m using the power-law wind profile. This adjustment results in non-negligible trend change. For instance, the increasing surface wind speed at Suwon station, which has six times of anemometer height changes in a range of 0.8 m to 20 m, is weakened up to 67% and becomes statistically insignificant. Likewise, the decreasing trend at Andong station, with three times of anemometer height changes in a range of 10 m to 15.5 m, is weakened up to 66%. A similar weakening in long-term trend is observed in most stations regardless of positive and negative trends. However, due to the cancellation between weakened negative trends and weakened positive trends, the station-averaged wind speed trend in Korea does not change much. This result suggests that anemometer height adjustment is crucial for evaluating local wind speed trend but its impact on nation-wide wind speed trend is rather minor.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권3호
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• pp.1345-1362
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• 2019

Most active queue management algorithms manage network congestion based on the size of the queue but ignore the network environment which makes queue size change. It seriously affects the response speed of the algorithm. In this paper, a new AQM algorithm named CT-AQM (Change Trend-Adaptive Queue Management) is proposed. CT-AQM predicts the change trend of queue size in the soon future based on the change rate of queue size and the network environment, and optimizes its dropping function. Simulation results indicate that CT-AQM scheme has a significant improvement in loss-rate and throughput.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.773-790
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• 2009

본 연구의 2004년 4월 서울 $\sim$ 부산의 고속철도 1단계 개통으로 기존 육상교통수단의 변화와 역세권 중심으로 생활권의 패턴변화가 발생하고 있다. 고속철도 개통으로 서울 $\sim$ 부산구간 통행시간이 4시간 10분에서 2시간 40분으로 단축되어, 이로 인한 인구의 이동, 기업이 입지, 공간구조의 개편 등 수단선택의 행태변화가 발생하고 있다. 본 연구는 서울 $\sim$ 천안/아산, 서울 $\sim$ 대전, 서울 $\sim$ 대구, 서울 $\sim$ 부산을 대상으로 고속철도 개통 후 발생하는 수단선택의 형태변화을 조사하여 이로부터 향후 수단선택에 영향을 미치는 인자를 분석하고자 한다. 이러한 1 단계의 고속철도 개통으로 인한 대상지역의 수단선택의 행태변화를 분석하여 향후 정부고속철도 2단계, 호남고속철도 개통으로 인한 거리별, 지역별, 수단별 형태의 변화 분석을 통해 정확한 수단변화를 통하여 도시공간구조개편, 광역교통체계의 계획시 좀 더 정확한 분석을 수행 활 수 있을 것으로 기대된다.

• The Journal of Korean Physical Therapy
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• 제34권2호
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• pp.51-56
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• 2022

Purpose: This study examined the effects of gym ball stabilization exercises on the physical functions of elementary school baseball players. Methods: The elementary school baseball players were assigned to an experimental group (n=21). The group performed gym ball stabilization exercises and the changes in the physical functions were measured using the visual response speed test, functional movements, physical balance ability, and pulmonary function. Results: The results of the visual response speed test showed changes in the time response speed. There was a significant change in the number of touches in 15 seconds in the upper arms and left and right legs (p<0.05) after 10 weeks. Also, there was a significant change in the reaction times of the left and right legs after 10 weeks (p<0.05). Further, there were significant differences in functional movements involving rotational stability and the total functional scores after 10 weeks (p<0.05). The player's body balance ability showed a significant difference after 10 weeks in the posterior-lateral and posterior-medial composite scores of the left and right legs (p<0.05). There was a significant change in the forced lung capacity and forced expiratory volume in 1 second after 10 weeks (p<0.05). Conclusion: These results show that the gym ball stabilization exercises effectively improved the visual response speed and functional movements, balance, and vital capacity of elementary school baseball players.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1221-1226
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• 2008

Present, the cooling method of using a phase-change heat transfer such as immersed type, heat pipe etc is applied in cooling of high-capacity power semiconductors of the main power system for the high speed train with the concentrated traction. In order to apply these phase-change cooling system to the high speed EMU to be developed, needed are technological researches of consideration of installing space, air passage, light weight material and miniaturization. Although this research establishes design specifications through theoretical analysis and computational analysis from the basic design process of the cooling system of the propulsion system for the high-speed EMU, when details design is completed, present improvement subject and optimum design before manufacturing the prototype of the cooling system on the basis of analysis results. And then, carried out will be the performance tests through prototype manufacture and reliability estimation by components of cooling system.