• 한국운동역학회지
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• 제14권1호
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• pp.83-98
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• 2004

The purpose of this study was to determine the kinematic variables of the hurdling for a korea record holder (A) and a national hurdle representative (B). after the kinematic variables such the distance and the distance and height of C.G, the velocity and the angle were analyzed about the hurdling. The results were summarized as follows; 1. In terms of the distance and the height of C.G, subject A showed long in horizontal distance from C.G to the take-off phase, but showed short in the landing phase. Subject B showed short in horizontal distance from C.G to the take-off phase, and showed long in the landing phase. 2. In terms of the velocity of C.G, Subject A showed fast C.G velocity in horizontal direction to the braking phase, Subject A and B showed slower C.G velority in the landing phase, but Subject A showed height C.G velocity in vertical direction to the to the take-off, the landing, and propulsion phase 3. In terms of the angle of C.G and lean of C.G to front at the braking and the take-off phase. Subject A kept the less angle in the maximum trunk lean to front at the flight phase as comparison with Subject B. 4. In terms of the velocity of the knee and the ankle joint. Subject A showed fast in the resultant velocity of the left ankle joint the take-off phase, but showed slow in the left knee joint. Subject B showed fast in the resultant velocity of the left knee joint the take-off phase, but showed slow in the right knee and the right ankle joint.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.191-193
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• 2006

The various wind turbines have been designed and developed for the century. The precision design of the blade and turbine system considering the wind circumstance is required for the high efficiency. In this paper, we investigated the output characteristics of the horizontal and vertical wind turbine related to the wind velocity. Furthermore we will intend to design the wind turbine blade adapted the urban wind circumstance.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.136-142
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• 2015

The shell and tube heat exchanger is an essential part of a power plant for recovering transfer heat between the feed water of a boiler and the wasted heat. The baffles are also an important element inside the heat exchanger. Internal materials influence the flow pattern in the bed. The influence of baffles in the velocity profiles was observed using a three-dimensional PIV (Particle Image Velocimetry) around baffles in a horizontal circular tube. The velocity of the particles was measured before the baffle and between them in the test tube. Results show that the velocity vectors near the front baffle flow along the vertical wall, and then concentrate on the upper opening of the front baffle. The velocity profiles circulate in the front and rear baffle. These profiles are related to the Reynolds number (Re) or the flow intensity. Velocity profiles at lower Re number showed complicated mixing to obtain the velocities and concentrate on the lower opening of the rear baffle as front wall. Numerical simulations were performed to investigate the effects of the baffle and obtain the velocity profiles between the two baffles. In this study, a commercial CFD package, Fluent 6.3.21 with the turbulent flow modeling, k-${\epsilon}$ are adopted. The path line and local axial velocities are calculated between two baffles using this program.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.235-236
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• 2022

In the present study, the effect of horizontal vent position on fire phenomena in the enclosure with vertical and horizontal vents was examined using numerical simulation. Case 1 indicates the condition that the horizontal vent is in the center of the ceiling. Case 3 indicates the condition that the horizontal vent is far away from the vertical vent. Case 2 indicates the condition that the horizontal vent is installed between Case 1 and Case 3. The temperature distribution, smoke layer temperature, velocity distribution, and mass flow rate of horizontal vent flow were analyzed. In Case 2, the temperatures were lowest and the mass flow rate through the horizontal vent was largest. This is because the flame is inclined by the inflow through the vertical vent. Hence, to determine the proper horizontal vent location for the high smoke ventilation performance, the inflow through the vertical vent and its effect on flame behavior should be considered.

• 한국지반공학회논문집
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• 제21권1호
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• pp.5-14
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• 2005

인천국제공항 공사현장의 흙막이 굴착단면에서 계측된 자료를 검토하여 연약지반에 설치된 강널말뚝 흙막이벽의 수평변위와 굴착주변지반의 변형에 대한 상관관계를 조사하였다. 벽체의 지지방식에 따른 강널말뚝 흙막이벽의 수평변위는 앵커지지, 복합지지, 버팀보지지 순으로 작게 나타났으며, 각각의 지지방식에 따른 최대수평변위 발생위치도 서로 다르게 발생하였다. 흙막이벽의 최대수평변위 및 최대수평변위속도는 굴착지반의 안정수가 ${\pi}$이하일 경우 각각 굴착깊이의 $1\%$, 1mm/day이하로 발생되고, 안정수가 ${\pi}+2$ 이하일 경우 각각 굴착깊이의 $2.5\%$, 2mm/day이하로 발생되며, 안정수가 ${\pi}+2$ 이상일 경우 급격하게 증가한다. 또한, 굴착저면에서의 N치가 감소함에 따라 흙막이벽의 최대수평 변위는 증가하며, N치가 약 10이하일 경우 흙막이벽의 최대수평변위는 급격하게 증가함을 알 수 있다. 한편, Terzaghi(1943)에 의해 제안된 히빙에 대한 안전율이 감소함에 따라 흙막이벽의 최대수평변위는 증가하며, 히빙의 안전율이 2.0일 경우 흙막이벽의 최대수평변위는 급속하게 증가함을 알 수 있다. 따라서, 국내 연약지반 강널말뚝 흙막이벽의 경우 히빙에 대한 안전율은 2.0으로 제안할 수 있다.

• 한국운동역학회지
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• 제14권3호
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• pp.135-147
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• 2004

This study was conducted to investigate the technical factors of Lu Yu Fu vault actually performed by three men gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu through the DLT method of three dimensional cinematography. To analyze these vaults, the instant events of Lu Yu Fu were set in the board touchdown(BTD), the board takeoff(BTO), the horse touchdown(HTD), the horse takeoff(HTO), the peak height(PH), the mat touchdown(MTD) respectively and the phases of that vault were set in the board contact(BC), the preflight(PRF), the horse contact(HC), the postflight(POF), the grounding on mat(GM) respectively After calculating the performance times, the CG displacement velocity, the kinetic energy impulse reaction force moment arm torque at the horse, the released angle piked angle addressed angle, the angular momentum angular velocity of whole body in x axis, and the horizontal displacement between the feet and CG, the following conclusions were reached. To perform the better Lu Yu Fu vault, a gymnast must have the large horizontal velocity of whole body with fast run-up, decrease the duration time and the horizontal vertical displacement of whole body in PRF, have the enough time to judge the correct magnitude and direction of force to brake or push the horse so as to lengthen the HC duration time at any cost. Also it is desirable to increase the horizontal vertical displacement of whole body in POF if possible, maintain the adequate piked position to decrease the angular velocity of whole body in x axis, prepare the grounding on mat previously and delay the release of the hand from the body to keep the angular momentum.

• 한국유체기계학회 논문집
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• 제20권1호
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• pp.53-58
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• 2017

This paper describes liquidity evaluation on the horizontal branch pipe connected to a food waste disposer and performance of five disposers marketed. Experimental apparatus for analyzing the five disposers has been introduced to measure vibration, sound level and power consumption of the disposers. Simulator for analyzing the required water velocity to avoid waste jam inside the pipe connected to a food waste disposer has been designed and constructed. The simulator can control some experimental parameters: pipe slope, disposer supply water quantity, food waste materials and operation time of a disposer. Throughout the experimental measurements of the disposers marketed, it is found that the time need to crash food waste is about 20 seconds on the average. At the same flow condition, increase rate of internal water velocity is accelerated as the pipe slope increases. The water velocity inside the pipe having 50 A and slope of 1/50 is 0.26 m/s when the water flowrate to supply the disposer is 16 l pm. Considering the specific gravity and adhesion property of food waste, water velocity of the horizontal branch pipe connected to a food waste disposer need to excess 0.26 m/s at least to avoid the waste blockage inside the pipe.

• 한국운동역학회지
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• 제16권4호
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• pp.13-20
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• 2006

A platform diving with categorizing 624C motion was video taped and 3D kinematic variables were analyzed. This motion is consist of 3 parts from the headstand position to the act of turning after take-off. The results indicated that it took a very short time from the moment of take-off to the act of 1/2 turning because the turning motion has already started from preparing motion even before the fingertips have parted from the ground. Also, there was barely any jumping height due to the use of upper limbs segment and there was little difference in the moving distance compared to the standing events judging from horizontal movement of 1.1m. The horizontal velocity of the center of human body was increased before take-off while the vertical velocity was decreased right after take-off and the velocity of lower limbs segment was faster than the upper limbs segment showing contrary results to the standing events. In the aspects of angular velocity, the upper limbs segment starts the turning motion when take-off by rapidly extending its angular velocity while lower limbs segment make large angular velocity even before take-off.

• 지질공학
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• 제25권2호
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• pp.273-280
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• 2015

강변여과수의 수평집수정 시공시 불균질성 지층에 의한 굴착 지연 등은 전체 굴착 공정에 영향을 미칠 수 있다. 본 연구에서는 안성천 지역에서 시공 중인 수평집수정의 굴착 과정에서 심도별로 취득된 입도분석 자료, 균등계수, 곡률계수를 활용하여 실제 굴착 속도를 추정하는 방안을 제시하였다. 균등계수와 곡률계수를 입력인자로 사용한 회귀식을 도출한 후 타 수평집수정에 적용한 결과, 조립질이면서 분급이 양호한 지층에 추정식이 잘 맞는 것으로 나타났다. 본 연구 결과는 중소규모의 하천을 대상으로 개발된 만큼, 향후 대하천 주변의 굴착 정보를 활용하여 추정식을 보완한다면 보다 정확한 설계 및 효율적인 시공 관리가 가능할 것이다.

• 설비공학논문집
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• 제15권2호
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• pp.109-115
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• 2003

The performance of two vertical-blade eliminators (V1, V2) and two horizontal-blade ones (H1, H2) for absorption chillers were tested in terms of pressure drop and refrigerant entrainment. The test was carried out using a wind tunnel with a cross section of 300 mm$\times$300 mm. The pressure drop of four eliminators tested was found to be in the rage of 1.0~2.7mm $H_2O$ at the face velocity of 2m/s. In the refrigerant entrainment test the vertical-blade eliminators showed much better performance than the horizontal-blade ones. The horizontal-blade eliminators showed satisfactory results at the air velocity of 2m/s but exceeded the limit value at 3 m/s. Since the cooling capacity of a machine is lowered by about 2.5% at the pressure drop of 1 m $H_2O$, more researches are required to reduce the pressure drop in the eliminator.